Combined Loss of the GATA4 and GATA6 Transcription Factors in Male Mice Disrupts Testicular Development and Confers Adrenal-Like Function in the Testes

Combined Loss of the GATA4 and GATA6
Transcription Factors in Male Mice Disrupts Testicular
Development and Confers Adrenal-Like Function in
the Testes
Maria B. Padua, Tianyu Jiang, Deborah A. Morse, Shawna C. Fox,
Heather M. Hatch, and Sergei G. Tevosian
Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville,
Florida 32610
The roles of the GATA4 and GATA6 transcription factors in testis development were examined by
simultaneously ablating Gata4 and Gata6 with Sf1Cre (Nr5a1Cre). The deletion of both genes
resulted in a striking testicular phenotype. Embryonic Sf1Cre; Gata4flox/flox
Gata6flox/flox
(condi-
tional double mutant) testes were smaller than control organs and contained irregular testis cords
and fewer gonocytes. Gene expression analysis revealed significant down-regulation of Dmrt1 and
Mvh.Surprisingly,Amhexpressionwasstronglyup-regulatedandremainedhighbeyondpostnatal
day 7, when it is normally extinguished. Neither DMRT1 nor GATA1 was detected in the Sertoli cells
of the mutant postnatal testes. Furthermore, the expression of the steroidogenic genes Star,
Cyp11a1, Hsd3b1, and Hsd17b3 was low throughout embryogenesis. Immunohistochemical anal-
ysis revealed a prominent reduction in cytochrome P450 side-chain cleavage enzyme (CYP11A1)-
and 3␤-hydroxysteroid dehydrogenase-positive (3␤HSD) cells, with few 17␣-hydroxylase/17,20
lyase-positive (CYP17A1) cells present. In contrast, in postnatal Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes, the expression of the steroidogenic markers Star, Cyp11a1, and Hsd3b6 was increased, but
a dramatic down-regulation of Hsd17b3, which is required for testosterone synthesis, was ob-
served. The genes encoding adrenal enzymes Cyp21a1, Cyp11b1, Cyp11b2, and Mcr2 were strongly
up-regulated, and clusters containing numerous CYP21A2-positive cells were localized in the in-
terstitium.Thesedatasuggestalackoftestisfunctionality,withalossofnormalsteroidogenictestis
function, concomitant with an expansion of the adrenal-like cell population in postnatal condi-
tional double mutant testes. Sf1Cre; Gata4flox/flox
Gata6flox/flox
animals of both sexes lack adrenal
glands; however, despite this deficiency, males are viable in contrast to the females of the same
genotype, which die shortly after birth. (Endocrinology 156: 1873–1886, 2015)
In most mammals, inheritance of the Y chromosome as-
sures commitment to a male fate. Sex determination be-
comes realized at midgestation through the expression of
the Y chromosome testis-determining gene Sry. SRY-de-
pendent activation of the transcription factor sex-deter-
mining region Y-box 9 (SOX9) orchestrates a cascade of
events leading to differentiation of the Sertoli cell popu-
lation that guides the conversion of the bipotential em-
ISSN Print 0013-7227 ISSN Online 1945-7170
Printed in U.S.A.
Copyright © 2015 by the Endocrine Society
Received November 13, 2014. Accepted February 6, 2015.
First Published Online February 10, 2015
For News & Views see page 1616
Abbreviations: AMH, anti-Müllerian hormone; BrdU, bromodeoxyuridine; CYP17A1, 17␣-
hydroxylase/17,20 lyase; CYP11A1, cytochrome P450 side-chain cleavage enzyme;
CYP21A2, cytochrome P450, family 21, subfamily A, polypeptide 2; DHH, desert hedge-
hog; DMRT1, doublesex and mab-3-related transcription factor 1; E, embryonic day;
FOXL2, forkhead box L2; GATA4, GATA binding protein 4; GATA6, GATA binding protein
6; GH2AX, gamma histone variant H2AX; H&E, hematoxylin and eosin; 3␤HSD, 3␤-hy-
droxysteroid dehydrogenase; IF, immunofluorescence; Insl3, insulin-like factor 3; MT-
hAMH, transgenic male mice overexpressing AMH; MVH, mouse vasa homolog; NR5A1/
AD4BP, nuclear receptor subfamily 5, group A, member 1/adrenal 4-binding protein; PND,
postnatal day; qPCR, quantitative RT-PCR; SF1, steroidogenic factor 1; SOX9, sex-deter-
mining region Y-box 9; Sry, sex determining region of Chr Y; STAR, steroidogenic acute
regulatory protein; WT1, Wilms’ tumor 1.
O R I G I N A L R E S E A R C H
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bryonic gonad into testes rather than ovaries (1, 2). After
sex determination, the testis forms two separate compart-
ments, the testicular cords and the interstitial region. The
interstitial region lies outside of the testis cords and con-
tains several cell types, most notably the steroidogenic fe-
tal Leydig cells (2). Normal development of fetal Leydig
cell progenitors depends on paracrine signaling instruc-
tions emanating from the Sertoli cells to initiate steroid-
ogenesis (3). The master regulator steroidogenic factor 1
(SF1) (SF1/NR5A1/Ad4BP, henceforth SF1) is at the helm of
the steroidogenic expression program in several endocrine
organs, including the testis, where it is the first genetic
marker that gives steroid-synthesizing cells their distinc-
tive identity and controls their metabolism, proliferation,
and survival (4).
In vertebrates, 6 GATA transcription factors act as key
regulators of the development of multiple tissues. Two of
these proteins, GATA4 and GATA6, are expressed in the
somatic cells of the embryonic testis (5). Early in gonadal
development, GATA4 in association with its cofactor
FOG2/ZFPM2 (friend of GATA/zinc finger protein mul-
tiple 2) acts to promote sex determination and testis dif-
ferentiation (6). The Cre-LoxP loss-of-function genetic
approach has been applied to clarify the role of GATA4 in
testis differentiation using testis-specific Cre drivers to di-
rect Gata4 gene deletion (7, 8). Sf1Cre; Gata4flox/flox
males develop partially descended small testes, exhibit a
short anogenital distance, and are infertile. The morphol-
ogy of the Sf1Cre; Gata4flox/flox
testis cords is irregular,
with numerous immature Sertoli cells being observed
within them. The expression of Dmrt1, one of the key
transcription factors in the male pathway (9, reviewed in
Ref. 10), is absent throughout embryogenesis (8). Sf1Cre
(11) effectively deleted Gata4 as early as embryonic day
(E)11.5–E12.5 in the precursors of Sertoli and Leydig cells
(8). In contrast, in Amrh2Cre; Gata4flox/flox
males, no ob-
vious defects were observed during embryonic or early
postnatal testis development, and the external genitalia
and testicular descent were normal. Adult Amrh2Cre;
Gata4flox/flox
males develop age-dependent infertility, ac-
companied by testicular atrophy and vacuolization of the
seminiferous tubules (7). Amhr2Cre is expressed in fetal
SertolicellsandinSertoliandLeydigcellspostnatally(12);
however, the extent of deletion in Sertoli vs Leydig cells
varieddependinguponthegenestudied(7,12).Therefore,
it is possible that the absence of a prenatal testicular phe-
notype is the result of a delayed or mosaic Amhr2Cre-
mediated recombination in the fetal testes (reviewed in
Ref. 13).
Although the involvement of GATA4 in regulating Ser-
toli cells is incontrovertible, the cell-autonomous role of
this protein in the steroidogenic interstitial cells is less
clear. XY GATA4-null embryonic stem cells are unable to
differentiate into Leydig cells (14); however, interstitial
cells expressing Leydig steroidogenic enzymes develop
normally in mice deficient in the GATA4 protein (8). The
presence of Gata6 in the developing mouse testis has been
long documented (5, 15), but no specific regulatory func-
tion has been assigned to GATA6 in any testicular lineage.
Given that GATA6 is coexpressed with GATA4 in the
testis, it is unknown whether their functions completely
overlap or whether GATA6 plays an independent role in
testis development. To address these questions, we carried
out a deletion of both Gata4 and Gata6 in the mouse
embryonic testis. Here, we report that these proteins ex-
hibit several overlapping functions in the Sertoli and Ley-
dig cells of the testis.
Materials and Methods
Generation of mouse strains
Procedures involving live animals were approved by the In-
stitutional Animal Care and Use Committees of University of
Florida. The Gata4flox/flox
and Gata6flox/flox
“flox” mice were
obtained from The Jackson Laboratory repository. The trans-
genic Sf1Cre mice (a gift from late Dr Parker) harbor Sf1 (Nr5a1)
regulatory elements driving Cre expression within a bacterial
artificial chromosome (BAC) (11). Strains carrying Sf1Cre-me-
diated deletions were produced by crossing flox mice with
Sf1Cre-containing animals, followed by backcross to generate
homozygous deletions. Sf1Cre; Gata6flox/flox
mice are fertile, but
Sf1Cre; Gata4flox/flox
mice are sterile (16). Therefore, Sf1Cre;
Gata4flox/ϩ
Gata6flox/flox
males were backcrossed with “double
flox” Gata4flox/flox
Gata6flox/flox
females to generate condi-
tional double mutants (Sf1Cre; Gata4flox/flox
Gata6flox/flox
).
Gata4flox/flox
Gata6flox/flox
animals were used as experimental
controls. The mice were maintained in a mixed 129/C57BL/6
genetic background. The primers used for genotyping (Inte-
grated DNA Technologies) are listed in Supplemental Table 1.
First-strand cDNA synthesis and quantitative
RT-PCR (qPCR)
Gonad-mesonephros complexes (for E13.5) and testes were
collected at different stages of development (E15.5 and E18.5
and postnatal day [PND]4, PND9, and PND47) from controls
and Sf1Cre; Gata4flox/flox
Gata6flox/flox
animals for RNA ex-
traction.TheconditionsaredescribedinSupplementalMaterials
and Methods. The primers used (Integrated DNA Technologies)
are listed in Supplemental Table 2.
Immunofluorescence (IF)
Testes were collected from control and Sf1Cre; Gata4flox/flox
Gata6flox/flox
animals (n ϭ 3 from each genotype) at different
stages of development (E13.5, E15.5, and E18.5 and PND4,
PND7, and PND30). IF experiments were carried out as previ-
ously described (16, 17). The primary antibodies and experi-
mental conditions are listed in the supplemental antibody table.
1874 Padua et al Role of GATA4 and GATA6 in Testicular Development Endocrinology, May 2015, 156(5):1873–1886

Hematoxylin and eosin (H&E) staining
Testes from controls and Sf1Cre; Gata4flox/flox
Gata6flox/flox
mice (n ϭ 2 from each genotype) were harvested at PND7,
PND17, and PND30 for histological analysis. Tissue sections
were processed as previously described (17).
Immunohistochemistry
Immunohistochemical reactions were performed with the
ImmPRESS polymerized reporter enzyme staining system kit
(Vector Laboratories, Inc), which uses peroxidase for detection.
The procedure is described in detail in Supplemental Materials
and Methods.
Intratesticular testosterone concentration
The intratesticular testosterone concentration was deter-
mined using the competitive Cayman’s testosterone enzyme im-
munoassay kit (Cayman Chemical Co), following the manufac-
turer’s guidelines. The procedure is described in the
Supplemental section.
Bromodeoxyuridine (BrdU) incorporation and
Terminal deoxynucleotidyl transferase dUTP Nick
End Labeling (TUNEL) assays
These procedures are described in Supplemental Materials
and Methods.
Whole-mount in situ hybridization
The procedure is described in Supplemental Materials and
Methods.
Results
Absence of doublesex and mab-3-related
transcription factor 1 (DMRT1) expression in the
E13.5 Sertoli cells of Sf1Cre; Gata4flox/flox
Gata6flox/flox
testis
In the testis, GATA4 is already present in the somatic
cells at E10.5 (8, 18, 19). Extending earlier observations
(5, 15), we show that GATA6 is detected in the Sertoli and
interstitial cells of control testis at E13.5 (Figure 1A).
GATA4 and GATA6 are coexpressed in the Sertoli cells
and in some interstitial (presumably Leydig cells) and coe-
lomic epithelial cells (Figure 1A). Sf1Cre-mediated recom-
bination is highly effective in the embryonic testis (com-
pare Figure 1, A and F), and expression of the GATA4 and
GATA6 proteins was no longer detectable in the somatic
cellsofSf1Cre;Gata4flox/flox
Gata6flox/flox
testesasearlyas
Figure 1. Gene expression analysis of E13.5 control and Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes. Representative sections of control (A–E) and
Gata6flox/flox
(F–J) testes at E13.5. Testicular sections were stained with antibodies against GATA4 (green) and GATA6 (red) (A
and F); DMRT1 (green) and SF1 (red) (B and G); AMH (green) and SOX9 (red) (C and H); the pluripotent germ cell marker OCT3/4 (green) and WT1
(red) (D and I); and the universal germ cell marker MVH (red) (E and K). Nuclei were stained with DAPI (blue). Scale bars represent 100 ␮m. TC,
testicular cords. K, Quantitative analysis of gene expression in Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes at E13.5. The examined genes were Amh,
Dhh, Dmrt1, Mvh, and Sox9. The results are shown as the mean Ϯ SEM of the fold change relative to controls for at least 4 biological replicates
(n ϭ 4), with significance considered at **, P Ͻ .01.
doi: 10.1210/en.2014-1907 endo.endojournals.org 1875

E13.5. As described previously (8, 20), residual coelomic
epithelial cells in the double mutant testis remained pos-
itive for GATA4 or GATA6, with some of these cells ex-
pressing both proteins (Figure 1F). The efficiency of
Sf1Cre in achieving the deletion of Gata genes remained
high on all subsequent embryonic and PNDs examined
(compare Figure 2, A and D and G and J, for E15.5 and
E18.5, respectively, and figures 4 and 5 PND4 and
PND30, respectively, below).
In mice, DMRT1 is expressed in the genital ridge in
both sexes until approximately E14.5, when it becomes
testis specific and is detected in both Sertoli and germ cells
(9, 21). IF experiments revealed that DMRT1 is expressed
in both the Sertoli cells (by colocalization with SF1) and
gonocytes of testes (Figure 1B). In contrast, the only cells
expressing DMRT1 in E13.5 Sf1Cre; Gata4flox/flox
Gata6flox/flox
testis were germ cells, whereas the Sertoli
cells were devoid of DMRT1 staining (Figure 1G). A sim-
ilar pattern of expression for DMRT1 was observed in
subsequent stages of embryonic development (compare
Figure 2, B and E and H and K, for E15.5 and E18.5,
respectively). Accordingly, gene expression analysis via
quantitative reverse transcription-polymerase chain reac-
tion also revealed significant down-regulation of Dmrt1
(P Ͻ .01) in all embryonic stages evaluated (Figures 1K
and 2, M and N).
In males, anti-Müllerian hormone (AMH) is responsi-
ble for the regression of the Müllerian ducts and is secreted
byfetalandearlypostnatalSertolicells(reviewedininRef.
22). The expression of Amh in mice begins at E11.5 (22–
Figure 2. The analysis of somatic gene expression at E15.5 and 18.5 in Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes. A–L, Representative images of
testicular sections from controls (A–C and G–I) and Sf1Cre; Gata4flox/flox
Gata6flox/flox
mice (D–F and J–L) at E15.5 (A–F) and E18.5 (G–L). The
sections were stained for GATA4 (green) and GATA6 (red) (A, D, G, and J); DMRT1 (green) and SF1 (red) (B, E, H, and K); and AMH (green) and
SOX9 (red) (C, F, I, and L). Nuclei were stained with DAPI (blue). Scale bars represent 100 ␮m. M and N, Gene expression analysis via qPCR in
Gata6flox/flox
testes at E15.5 (M) and E18.5 (N). The examined transcripts were Amh, Dhh, Dmrt1, Mvh, Sf1, Sox9, Gata4, and
Gata6. The results are graphed as the mean Ϯ SEM of the fold change relative to controls, from n ϭ 5 for E15.5 and n ϭ 4 for E18.5 biological
replicates, with significance considered at *, P Ͻ .05; **, P Ͻ .01; and ***, P Ͻ .001.

24). During embryogenesis (E13.5 to E18.5), AMH was
expressed by the Sertoli cells of both the controls and the
double mutant testes (Figures 1, C and H, and 2, C and F
and I and L). Early in development (E13.5), the expression
of Amh in Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes was
no different from that in controls. In contrast, Amh ex-
pression was significantly up-regulated (P Ͻ .01) in the
double mutant testes at E15.5 (Figure 2M); this trend con-
tinued at E18.5, although it was not significant (Figure
2N).
Similar to AMH, the SOX9 transcription factor is ex-
pressed by the pre-Sertoli cells and is a major protein pro-
moting their subsequent differentiation (25, 26). SOX9 is
first detectable in the bipotential gonad, and at E11.5, its
expression becomes notably up-regulated in the testes and
down-regulated in the ovaries (1). Previous work demon-
strated that Amh expression is directly controlled by
SOX9 through its binding site in the Amh promoter (27).
SOX9 was immunolocalized to the Sertoli cells, with no
detectable changes in the pattern of expression in Sf1Cre;
Gata4flox/flox
Gata6flox/flox
testes compared with the con-
trolsinallembryonicstagesexamined(Figures1,CandH,
and 2, C, F, I, and L). Similarly, quantitative assessment of
Sox9 expression did not reveal any significant changes in
double mutant testes relative to the controls (Figures 1K
and 2, M and N). Another important signaling molecule
produced by Sertoli cells is the desert hedgehog (DHH)
protein. DHH is required for the differentiation of ste-
roidogenic fetal Leydig cells (28, 29). In mice, Dhh ex-
pression in the testis is detected at E11.5 and continues
throughout embryogenesis (6, reviewed in Ref. 3). The
expression of Dhh in Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes was normal (Figures 1K and 2, M and N).
Abnormal testis cord architecture and decreased
numbers of gonocytes in Sf1Cre; Gata4flox/flox
Gata6flox/flox
embryonic testis
At E13.5, we observed no notable difference in the
overall number of primordial germ cells (by IF staining for
themousevasahomolog[MVH],thepluripotentgermcell
marker, POU domain, class 5, transcription factor 1
(OCT3/4), and via qPCR) between control and double
mutant testis (compare Figure 1, D, E, I, and J, respec-
tively). However, an irregular distribution of gonocytes in
the disorganized testis cords of the Sf1Cre; Gata4flox/flox
Gata6flox/flox
testis was already prominent. A dramatic
reduction in the overall number of gonocytes became ap-
parent in subsequent stages of embryonic development
(E15.5 and 18.5) (compare Figure 3, C and G and D and
H). Accordingly, significant down-regulation of the Mvh
transcript was detected at both E15.5 and E18.5 (Figure 2,
M and N).
The smaller size of Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes compared with the control organs was notable at the
earliest stage we analyzed, E13.5 (Figures 1, A and F, and
2, G and J). To determine whether cell proliferation is
compromised in the double mutant testes, we used BrdU
DNA labeling. Numerous BrdU-labeled cells were ob-
served in both and Sf1Cre; Gata4flox/flox
Gata6flox/flox
tes-
tes at E15.5 (Supplemental Figure 1, A–C and F–H) and
E17.5 (Supplemental Figure 1, D, E, I, and J). Colocaliza-
tion of BrdU-positive cells with the Wilms’ tumor 1 (WT1)
protein showed that somatic (mostly Sertoli) cells prolif-
erate normally in both genotypes at E15.5 (Supplemental
Figure 1, D and H). The ratio of BrdU-labeled cells to
4Ј,6-diamidino-2-phenylindole (DAPI)-positive cells did
Figure 3. Decrease in gonocyte numbers and loss of the testis architecture in Sf1Cre; Gata4flox/flox
Gata6flox/flox
males. Representative sections of
control (A, C, E, and G) and Sf1Cre; Gata4flox/flox
Gata6flox/flox
(B, D, F, and H) testes at E15.5 (A–D) and E18.5 (E–H). The sections were stained for
AMH (green) and the universal germ cell marker MVH (red) (A, B, E, and F); and Laminin (green) and MVH (red) (C, D, G, and H). Nuclei were
stained by DAPI (blue). Scale bars represent 100 ␮m. TC, testis cords.

not differ between the control and double mutant testes at
E17.5 (Supplemental Figure 1K)
In contrast, analysis of cell death using TUNEL staining
revealed more apoptotic nuclei in Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes (Supplemental Figure 2, B and C) than
in controls (Supplemental Figure 2A) at E15.5. Numerous
apoptotic nuclei were localized proximal to the coelomic
epitheliumatbothembryonicpointsexamined(E15.5and
E17.5) (Supplemental Figure 2, B and E). Similarly, a
greater number of gonocytes (identified based on colocal-
ization with MVH) was undergoing cell death in the dou-
ble mutant testes (Supplemental Figure 2C).
GATA1 is not expressed in the Sertoli cells of
Gata6flox/flox
testes
The GATA1 protein figures prominently in hemato-
poietic development and is required for normal erythroid
and megakaryocytic development (reviewed in Ref. 30).
GATA1 is absent from the developing gonad but becomes
robustly expressed in the testis shortly after birth. Curi-
ously, the Sertoli cells of the postnatal testis are the only
known extrahematopoietic site of Gata1 expression (31,
32, reviewed in Refs. 33, 34). It has previously been re-
ported that GATA1 is dispensable for Sertoli cell function
and for the expression of a number of testis-specific genes
(35, 36). We considered the possibility that upon the de-
letion of both Gata4 and Gata6, Gata1 could display a
compensatory function for Sertoli gene expression. Unex-
pectedly, we observed that after the deletion of Gata4 and
Gata6, GATA1 expression in Sertoli cells did not com-
mence as normal in the postnatal double mutant testis
(compare Figures 4, B and C and G and H, and 5, D and
H). The absence of Gata1 expression was corroborated
through qPCR (P Ͻ .001) (Figures 4K and 5I). Thus, our
model allows the analysis of testis gene expression in the
absence of all 3 GATA factors. To verify that the absence
of GATA1 alone is insufficient to exert changes in the
somatic or germ cells, we examined gene expression in
the Gata1 transgenic model in which the transgene res-
cues Gata1 expression exclusively in the hematopoietic
cell compartment of the Gata1-null mice, but nowhere
else in the animal (ensuring the survival of the otherwise
lethal Gata1 gene deletion) (35). We observed no dif-
ferences in the expression patterns of the GATA4,
GATA6, and H2AX proteins (Supplemental Figure 3);
AMH expression was also not elevated in the absence of
GATA1.
Similarly, the DMRT1 protein was virtually absent in
the Sertoli cells of postnatal Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes (compare Figures 4, D and L, and 5, N
and S). The DMRT1-positive cells remaining in double
mutant testes were mostly spermatogonial cells; only rare
Figure 4. GATA1 expression is lost in Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes at PND4. Representative images of testicular sections from controls
(A–E) and Sf1Cre; Gata4flox/flox
Gata6flox/flox
mice (I–M) at PND4. The sections were stained for GATA4 (green) and GATA6 (red) (A and F); GATA1
(green) and WT1 (red) (B and G); DMRT1 (green) and SF1) (red) (D and I); and AMH (MIS; green) and SOX9 (red) (E and J). C and H, Higher
magnifications of B and G, respectively. The arrow in I points to the few DMRT1 and SF1 double-positive cells in the double mutant testis. Scale
bars represent 100 ␮m (B, F, G, I, and J), 50 ␮m (A, D, and E), or 20 ␮m (C and H). K, Examination of gene expression via qPCR in Sf1Cre;
Gata4flox/flox
Gata6flox/flox
testes at PND4. The examined transcripts were Amh, Dmrt1, Gata1, Mvh, Sox9, Gata4, and Gata6. The results are shown
as the mean Ϯ SEM of the fold change relative to controls from at least n ϭ 3 biological replicates, with significance considered at **, P Ͻ .01
and ***, P Ͻ .001.

DMRT1-positive cells were observed among the Sertoli
cells (double DMRT1; SF1-positive) (Figure 4I, arrow). In
agreement with these results, gene expression analysis re-
vealed significant down-regulation of Dmrt1 expression
(P Ͻ .001) at all postnatal stages evaluated (Figures 4K
and 5T). It has been reported that loss of Dmrt1 expres-
sion in the Sertoli cells (but not germ cells) leads to sex
reversal, defined by ectopic expression of the female-spe-
cific transcription factor FOXL2 in the Sertoli cells of
PND28 mouse testes (37). Although the expression of the
Dmrt1genewasdramaticallydown-regulatedandprotein
staining was virtually absent in Sf1Cre; Gata4flox/flox
Gata6flox/flox
Sertoli cells at all developmental stages ex-
amined, IF experiments did not detect FOXL2-positive
cells in the PND30 double mutant testis (data not shown).
Although qPCR at PND47 detected a tendency for the
increased expression of Foxl2, it was not statistically sig-
nificant (P ϭ .07) (Figure 5T).
Continuous expression of AMH and atypical
distribution of spermatogonia in Sf1Cre;
Gata4flox/flox
Gata6flox/flox
testes after PND7
AMH is expressed in the mouse testis throughout em-
bryonic development until birth, when its expression be-
gins to decline. We noted that at PND7 AMH protein is
sharply reduced in the Sertoli cells of control testes (Figure
5, B and C) and becomes completely absent by PND30
(Figure 5M). In contrast, the expression of AMH in the
Sertoli cells of Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes
remained high postnatally (Figure 5, F and R, for PND7
and PND30, respectively). qPCR experiments verified the
IF data and corroborated significant up-regulation of
AmhexpressionatPND9(PϽ.05)(Figure5I)andPND47
(P Ͻ .01) (Figure 5T). No postnatal changes in the ex-
pression of its major regulator SOX9 (27), determined
either via IF at PND7 (Figure 5, D and H) or qPCR at
PND9 (Figure 5I), were observed in double mutant testes.
Figure 5. Persistent AMH expression in Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes after PND7. Representative images of testicular sections from
controls (A–D and J–N) and Sf1Cre; Gata4flox/flox
Gata6flox/flox
mice (E–H and O–S) at PND7 (A–H) or PND30 (J–S). PND7 sections were stained with
H&E (A and E) and with antibodies against AMH (green) and phosphorylated histone family protein H2A (G-H2AX) (red) (B and F); or against
GATA1 (green) and SOX9 (red) (D and H). C and G, Higher magnifications of B and F, respectively. PND30 sections were stained with H&E (J and
O) and with antibodies against GATA4 (green) and GATA6 (red) (L and Q); AMH (green) and MVH (red) (M and R); or against DMRT1 (green) and
SF1 (red) (N and S). DAPI (blue) was used for nuclear staining. K and P, Higher magnifications of J and O, respectively. In panels R and S, arrows
point to the remaining spermatogonia in Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes. Scale bars represent 200 ␮m (A, E, J, and O), 100 ␮m (F, H, L–N,
and Q–S), 50 ␮m (B, D, K, and P), or 20 ␮m (C and G). I and T, Analysis of gene expression via qPCR in Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes at
PND9 (I) and PND47 (T). The analyzed genes were Amh, Dmrt1, Foxl2, Gata1, Mvh, Sox9, Gata4, and Gata6. The bar graphs represent the
mean Ϯ SEM of the fold change relative to controls from at least n ϭ 3 biological replicates, with significance considered at *, P Ͻ .05; **, P Ͻ
.01; and ***, P Ͻ .001.

These results are similar to those obtained at the prenatal
time points we have evaluated.
Postnatal Sf1Cre; Gata4flox/flox
; Gata6flox/flox
testes are
remarkably underdeveloped (compare Figure 5, A and J
and E and O, respectively). In particular, at PND30, the
diameter of the seminiferous tubules is markedly smaller
in the double mutant testis than in controls (compare Fig-
ure 5, K and P), with fewer spermatogonia and Sertoli
(somatic) cells being observed within each testicular cord.
Furthermore, in the postnatal testes, localization of the
spermatogonia adjacent to the basement membrane of the
testis cords is evident (G-H2AX-positive cells in Figure 5,
B and C; cells with large purple nuclei in Figure 5K; and
DMRT1-positive cells in Figure 5N), whereas in PND7
Gata6flox/flox
testes, only rare sper-
matogonia migrated to the basement membrane (Figure 5,
F and G). The numbers of germ cells continued to decline
in conditional double mutant testes, and at later postnatal
stages, the expression of Mvh became significantly lower
(P Ͻ .01) (Figure 5T); very few spermatogonia were de-
tected by IF (Figure 5, R and S, arrows).
The steroidogenic pathway is compromised in
Gata6flox/flox
fetal testes
Interstitial Leydig cells are responsible for the produc-
tion of testosterone that ensures the persistence of the
Wölffian ducts and stimulates their subsequent differen-
tiation into organs of the male reproductive tract (re-
viewed in Ref. 38). Several enzymes have been implicated
in the synthesis of testosterone from its precursor choles-
terol, including the steroidogenic acute regulatory protein
(STAR), cytochrome P450 side-chain cleavage enzyme
(CYP11A1), 17␣-hydroxylase/17,20 lyase (CYP17A1),
3␤-hydroxysteroid dehydrogenase (3␤HSD), and 17␤HSD
(38). Two populations of Leydig cells are recognized in ro-
dents: the fetal population, which arises after sex determi-
nation and declines shortly after birth, and the adult popu-
lation,whichemergesduringthefirst2weeksafterbirthand
remains throughout adulthood (3, 39). Unlike adult Leydig
cells, the fetal Leydig population is presumed to synthesize
testosterone in a pituitary-independent manner (40).
Immunohistochemical assessment of steroidogenic en-
zymes in control testes showed robust staining corre-
sponding to the CYP11A1, 3␤HSD, and CYP17A1 pro-
teins in the interstitial fetal Leydig cells at E15.5 and E18.5
(Figure 6, A–C and J–L, respectively). In contrast, in the
Gata6flox/flox
testes, we observed a
major reduction in the number of cells expressing
CYP11A1 and 3␤HSD at both embryonic developmental
stages examined (Figure 6, D and E and M and N). More-
over, only occasional CYP17A1-positive cells were im-
munolocalizedinthedoublemutanttestisatE15.5(Figure
6, F and I), which became completely undetectable at
E18.5 (Figure 6O). qPCR confirmed the significant down-
regulation of all of the steroidogenic genes examined, at
both E13.5 and E15.5 (Figure 6, P and Q), in the Sf1Cre;
Gata4flox/flox
Gata6flox/flox
testes. In agreement with these
results, whole-mount in situ hybridization experiments
performed at E15.5 demonstrated the same strong down-
ward trend of Cyp11a1, Cyp17a1, and Hsd17b3 RNA
expression in the double mutant testes (Supplemental Fig-
ure 4). Similarly, at E18.5, most of the steroidogenic genes
were down-regulated, including Cyp11a1 (P Ͻ .01),
Hsd3b1 (P Ͻ .01), and Hsd17b3 (P Ͻ .001); only Hsd3b6
was significantly up-regulated (P Ͻ .001) (Figure 6R).
Leydig cells also express insulin-like factor 3 (Insl3), a
peptide hormone that is critical for testicular descent (41;
reviewed in Refs. 22, 42). In mice, Insl3 has been detected
as early as E12.5 (43). Quantitative analysis of Insl3 ex-
pression in Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes re-
vealed a significant reduction of the transcript throughout
embryogenesis (E13.5, P Ͻ .05; E15.5, P Ͻ .001; and
E18.5, P Ͻ .05) (Figure 6, P–R), which may explain the
undescended intraabdominal position of the double mu-
tant testes proximal to the kidneys (Supplemental Figure
5, A and B). This phenotype is similar, but more severe
than that of the Sf1Cre; Gata4flox/flox
males, in which the
testespartiallydescend(8);however,distinctfromSf1Cre;
Gata6flox/flox
males in which testicular development is
normal (Supplemental Figure 6).
Increased expression of steroidogenic genes in
Gata6flox/flox
postnatal testes
Before birth, a profound decrease in the steroidogenic
competence of the Sf1Cre; Gata4flox/flox
Gata6flox/flox
double mutant testis is observed (Figure 6). In contrast,
CYP11A1- and 3␤HSD-positive cells become abundant in
the interstitial region of the double mutant testis at PND4
(Figure 7, D and E, respectively). Gene expression analysis
via qPCR confirmed the significant up-regulation of the
expression of the steroidogenic genes Star (P Ͻ .001),
Cyp11a1 (P Ͻ .01), and Hsd3b6 (P Ͻ .001) in double
mutant testes (Figure 7M).
Abundant CYP11A1- and 3␤HSD-positive cells were
also present in the testes of the Sf1Cre; Gata4flox/flox
Gata6flox/flox
animals at PND30; however, the distribu-
tion of steroidogenic cells was notably different from that
at PND4. Most the CYP11A1- and 3␤HSD-positive cells
were clustered proximal to the coelomic epithelium (Fig-
ure 7, J and K, respectively), with only scattered
CYP11A1- and 3␤HSD-positive cells being localized in
the interstitial region. Additionally, qPCR experiments
conducted at PND47 (Figure 7N) showed that although
the expression of some markers of steroidogenic cells

(Cyp11a1 and Hsd3b6) did not differ from that in control
testes, others (Star and Hsd3b1) were significantly up-
regulated in the double mutant testes (P Ͻ .01 and P Ͻ .05,
respectively).
Intriguingly, Hsd3b6 expression has been associated
with adult Leydig cells (44, 45; however, see Ref. 46).
Because we observed premature (E18.5) up-regulation of
Hsd3b6 as well as an increase in the steroidogenic cell
population in Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes at
PND4, we evaluated the possibility that adult Leydig cells
appear precociously in the double mutant testes. Normal
adult Leydig cell function is dependent on pituitary LH
and requires expression of the LH receptor, Lhr (40). We
examined the expression of Lhr via qPCR and found it to
be down-regulated in the double mutant testes at both
PND4 and PND47 (P Ͼ .01 and P Ͼ .05, respectively).
Additionally, similar to the embryonic points we evalu-
ated, no CYP17A1-positive cells were observed in the
Gata6flox/flox
testes at PND4, with
such cells only rarely being detected at PND30 (Figure 7,
F and L), and the expression of Hsd17b3 was significantly
lower (P Ͻ .001) at PND4 and PND47 (Figure 7, M and
N). Furthermore, testosterone synthesis was significantly
reduced in the double mutant testes, as assessed via ELISA
(Figure 7O), and testosterone-responsive tissues, such as
seminal vesicles and submaxillary glands, were severely
affected in Sf1Cre; Gata4flox/flox
Gata6flox/flox
males (Sup-
plemental Figure 5, C–E). In summary, these data suggest
that premature differentiation of adult Leydig cells in
Gata6flox/flox
animals is an unlikely
explanation for the increased activity of the selected ste-
roidogenic genes observed in the double mutant testes.
Overexpression of adrenal genes and clusters of
CYP21A2 cells in conditional double mutant testes
It has long been proposed that steroidogenic adreno-
cortical and testis cells are derived from a common pro-
genitor population of the adrenogonadal primordium (4,
47, 48). However, it was only recently demonstrated that
the fetal mouse testis harbors a limited number of cells that
Figure 6. Analysis of steroidogenic enzyme expression during embryogenesis in Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes. Sections of control (A–C
and J–L) and Sf1Cre; Gata4flox/flox
Gata6flox/flox
(D–F and M–O) testes at E15.5 (A–F) and E18.5 (J–O) were stained for CYP11A1 (A, D, J, and M),
3␤HSD (B, E, K, and N), and CYP17A1 (C, F, L, and O). G–I, Higher magnifications of D–F, respectively. Note the reduced number of CYP11A1-
positive (D and M), 3␤HSD-positive (E and N), and CYP17A1-positive (F and O) cells in Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes at both
developmental stages. Scale bars represent 100 ␮m (A–F and J–O) and 50 ␮m (G–I). P–R, qPCR analysis of changes in the expression of Star,
Cyp11a1, Hsd3b1, Hsd3b6, Hsd17b3, and Insl3 in Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes at E13.5 (P), E15.5 (Q), and E18.5 (R). The results are
plotted as the mean Ϯ SEM of the fold change relative to controls from at least n ϭ 3 biological replicates for E13.5 and E15.5 and n ϭ 4
biological replicates for E18.5, with significance considered at *, P Ͻ .05; **, P Ͻ .01; and ***, P Ͻ .001.

express Cyp11b1 and Cyp21a1, which are genes that en-
code enzymes required for corticosteroid synthesis (49,
50). Interestingly, Sf1Cre; Gata4flox/flox
Gata6flox/flox
an-
imals do not develop adrenal glands (S.G. Tevosian, E.
Jiménez, H.M. Hatch, T. Jiang, D.A. Morse, S.C. Fox,
M.B. Padua, manuscript submitted); however, males sur-
vive and live normal lifespans, in contrast to their female
littermates, which die shortly after birth (17).
We hypothesized that steroidogenic gene expression in
the testes of Sf1Cre; Gata4flox/flox
Gata6flox/flox
animals
stems from the expansion of their adrenal-like population.
As early as PND4, we detected overexpression of the ad-
renal genes Mc2r (P Ͻ .001), Cyp21a1 (P Ͻ .001),
Cyp11b1 (P Ͻ .01), and Cyp11b2 (P Ͻ .01) in Sf1Cre;
Gata4flox/flox
Gata6flox/flox
testes (Figure 8I), and the same
trend was observed at later stages (Figure 8J). Histological
analysis of the double mutant testis at PND17 revealed the
presence of clusters of hypertrophic cells localized in the
interstitial region, proximal to the coelomic epithelium
(Figure 8F, arrowheads). CYP21A2, a key enzyme com-
mon to the synthesis of the adrenocortical hormones cor-
ticosterone and aldosterone, was similarly immunolocal-
ized in the interstitial region at PND17 and PND30,
within the cells clustered in the subepithelial zone (Figure
8, G and H, arrows). We concluded that the steroidogenic
expression observed in the testes of the Sf1Cre; Gata4
flox/flox
Gata6flox/flox
animals is derived not from the fetal or adult
Leydig cells but from the expanded adrenocortical-like
population.
Discussion
Previously, we and others demonstrated that the GATA4
transcription factor is required for the normal develop-
ment and function of the reproductive organs of both
sexes, ie, the testes (7, 8) and ovaries (16, 51). Now, we
show that the deletion of both GATA transcription factors
GATA4 and GATA6 within the somatic compartment of
the testis reveals a synergistic function for these proteins in
testis differentiation. Male of the Sf1Cre; Gata4flox/flox
Gata6flox/flox
genotype develop small, nondescended tes-
tes, with irregular testis cords, and only a low number of
gonocytes/spermatogonia are found at puberty. Not sur-
prisingly, these conditional double mutant males are
sterile.
Our data suggest that the reduction in the size of the
double mutant testes is caused by an imbalance between
cell proliferation and cell death. Although the proportion
of proliferating cells in embryonic Sf1Cre; Gata4flox/flox
Figure 7. Analysis of steroidogenic enzymes in the postnatal Sf1Cre; Gata4flox/flox
Gata6flox/flox
testis. Sections of control (A–C and J–L) and
Gata6flox/flox
(D–F and M–O) testes at PND4 (A–F) or PND30 (G–L) were stained for CYP11A1 (A, D, G, and J), 3␤HSD (B, E, H,
and K), and CYP17A1 (C, F, I, and L). Scale bars represent 200 ␮m (G–L) and 100 ␮m (A–F). M and N, qPCR analysis of changes in the expression
of Lhr, Star, Cyp11a1, Hsd3b1, Hsd3b6, and Hsd17b3 in Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes at PND4 (M) and PND47 (N). The bar graphs
represent the mean Ϯ SEM of the fold change relative to controls from at least n ϭ 3 biological replicates for both developmental stages, with
significance considered at *, P Ͻ .05; **, P Ͻ .01; and ***, P Ͻ .001. O, Intratesticular testosterone concentrations (pg/mL) in controls (black bar)
and Sf1Cre; Gata4flox/flox
Gata6flox/flox
(gray bar) animals at PND Ն 120. The bar graph shows the mean concentration adjusted per mg of testicular
tissue Ϯ SEM from n ϭ 3 biological replicates of each genotype. The data were analyzed using Student’s t test, with significance considered at
***, P Ͻ .001.

Gata6flox/flox
testes does not differ from that in controls, a
greater number of apoptotic nuclei were detected in both
the somatic and germ cells of double mutant testes. The
precocious death of gonocytes at E17.5 is likely to be
the main reason for the low number of spermatogonia in
theadulttestes.Itispossiblethatthesurvivalofgonocytes/
spermatogonia was negatively affected by the disorgani-
zation of the testis cords in the mutants. Disorganized
testis cords are known to disrupt the positioning and in-
teraction of Sertoli cells and gonocytes/spermatogonia
within them (52). In addition, there is experimental evi-
dence suggesting the importance of Leydig cells in main-
taining testis cord structure and ensuring germ cell sur-
vival (29, 53–55). Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes are devoid of fetal and adult Leydig cells. It is pos-
sible that in addition to the viability, the development of
the germ cells in Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes
is also affected. However, we did not specifically assess the
status of germ cell differentiation in the double mutant
testes beyond their ability to initiate G-H2AX expression.
The transcription factor SOX9 is a key regulator of
Sertoli cell differentiation (reviewed in Refs. 1, 56). The
levels of SOX9 were not affected in Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes. However, we observed abundant ap-
optotic nuclei near the coelomic epithelium in the embry-
onic double mutant testes. Sertoli cells differentiate from
precursors derived from the coelomic epithelium (57) that
express the GATA4 protein (18). Sf1Cre-mediated loss of
GATA proteins may preferentially affect the viability of
the transitional Sertoli cell progenitors.
Unlike SOX9, DMRT1 and GATA1 were strongly
down-regulated in the Sertoli cells of Sf1Cre; Gata4flox/flox
Gata6flox/flox
testis. We previously showed that DMRT1 is
lostfromtheSertolicellsofSf1Cre;Gata4flox/flox
testesbut
only during embryogenesis (8). This pattern differs from
that in the double mutant testis, where somatic DMRT1 is
also undetectable postnatally (eg, at PND47), suggesting
a role for GATA6 and/or GATA1 in the postnatal expres-
sion of Dmrt1. The GATA1 testis-specific promoter ele-
ment contains a conserved GATA site (58), and it is likely
that GATA1 is a direct target of GATA4 and GATA6 in
Sertoli cells.
In contrast, AMH is highly up-regulated in the postna-
tal Sf1Cre; Gata4flox/flox
Gata6flox/flox
testis. It has been
proposed that GATA proteins are required for the regu-
lation of Amh expression (59). Here, we show that AMH
isexpressedintheSertolicellsoftheembryonictestisinthe
absence of GATA4 and GATA6 and is ectopically ex-
pressed in the adult testis in the absence of all 3 GATA
proteins (GATA1, GATA4, and GATA6). We conclude
that Amh gene expression does not require GATA func-
tion in males.
Interestingly, previously described transgenic male
mice overexpressing AMH (MT-hAMH) exhibit a low
number of mature Leydig cells and significant reduction of
serum testosterone; hence, their virilization is incomplete
(60, 61). These characteristics resemble the phenotype of
the Sf1Cre; Gata4flox/flox
Gata6flox/flox
males, in which the
external genitalia were underdeveloped (data not shown)
and the concentration of intratesticular testosterone was
dramatically reduced. We also showed that the expression
of Hsd17b3, the enzyme responsible for testosterone syn-
thesis, was significantly down-regulated. However, in
MT-hAMH animals, Lhr expression is increased 5-fold,
Figure 8. Adrenocortical genes are overexpressed in Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes as early as PND4. Representative sections of control
(A–D) and Sf1Cre; Gata4flox/flox
Gata6flox/flox
(E–H) testes at PND17 (A–C and E–G) or PND30 (D and H) were stained with H&E (A and E) and for
CYP21A2 (C, D, G, and H). B and F, Higher magnifications of A and E, respectively. The arrowheads in F indicate a cluster of hypertrophic cells
localized in the interstitial region. Scale bars represent 200 ␮m (A, C–E, G, and H) or 100 ␮m (B and F). I–J, Quantitative changes in the expression
of the adrenal transcripts Mc2r, Cyp21a1, Cyp11b1, and Cyp11b2 in Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes at PND4 (I) and PND47 (J). The results
are graphed as the mean Ϯ SEM of the fold change relative to controls from at least n ϭ 3 biological replicates, with significance considered at
**, P Ͻ .01 and ***, P Ͻ .001.

some steroidogenic enzymes are down-regulated, and the
diameter of the seminiferous tubules and spermatogenesis
are normal (61). Thus, the MT-hAMH testicular pheno-
type is distinctly different from that observed in the
Gata6flox/flox
testes. Hence, it is
highly unlikely that the up-regulation of AMH in the
Gata6flox/flox
testes is solely respon-
sible for their phenotype.
In Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes, 2 distinct
patterns of the expression of genes encoding steroidogenic
enzymes could be distinguished: embryonic and postnatal,
with both patterns differing from those in the controls. In
the embryonic double mutant testes, a strong decline in the
expression of most steroidogenic enzymes is observed
(with only Hsd3b6 being overexpressed). In contrast, the
same steroidogenic gene set is up-regulated in the Sf1Cre;
Gata4flox/flox
Gata6flox/flox
testis right after birth. We ex-
ploredthepossibilityofprecociousdifferentiationofadult
Leydig cells in double mutant testes based on the early
up-regulation of Hsd3b6, which is known to be expressed
in adult, but not fetal Leydig cells (44, 45). This possibility
was found to be inconsistent with the overall gene expres-
sion pattern in the early postnatal testis of the double mu-
tants.Forexample,LHisrequiredfornormaladultLeydig
cell function, and the LH receptor is up-regulated in adult
Leydig cells (40). However, Lhr was down-regulated in
the postnatal Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes.
Moreover, in addition to the expression of Hsd3b6 in
adult Leydig cells, recent work revealed robust Hsd3b6
expression in the adrenal glands (46). Yamamura et al also
established that another Hsd3b isoform, Hsd3b1, is ex-
pressed much more efficiently by adrenocortical cells (46)
compared with the Leydig cells (45, 46). Hsd3b1 expres-
sion was increased in the postnatal Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes. In addition, the Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes expressed common enzymes required
for the androgenic and glucocorticoid/mineralocorticoid
pathways (Star, Cyp11a1 and Hsd3b6, and Hsd3b1),
whereas the level of Hsd17b3, the gene encoding the key
enzyme for testosterone synthesis, was significantly
reduced.
In summary, these data suggest that the cellular clusters
found in Sf1Cre; Gata4flox/flox
Gata6flox/flox
testes ex-
pressingsteroidogenicenzymesarenotLeydigcells,butan
adrenocortical-like population. These clusters are likely
derived from the expansion of the rare adrenal-like cells
present in the developing testis (49, 50). In the normal
testis, the significance of the presence of these cells is cur-
rently unknown. It has been hypothesized that these cells
are merely misallocated to the testes during the separation
of the adreno-gonadal primordia (49). However, a role for
these cells in normal testis development cannot be
excluded.
In contrast to the androgen synthesis pathway, which is
notably compromised in the Sf1Cre; Gata4flox/flox
Gata6flox/flox
testis, the corticosteroid and mineralocorti-
coid pathway is fully active in the testis of these animals,
with overexpression of the adrenal enzymes Cyp21a1,
Cyp11b1, Cyp11b2, and Mcr2 being observed. This is the
most parsimonious explanation for the normal lifespan of
the Sf1Cre; Gata4flox/flox
Gata6flox/flox
males, whereas
their female littermates all die within 2 weeks after birth
(17). Intriguingly, human patients with congenital adrenal
hyperplasia develop testicular adrenal rest tumors that ex-
press the adrenal cortex-specific genes CYP11B1,
CYP11B2, and MC2R (62). However, and distinct from
Gata6flox/flox
testis, testicular adre-
nal rest tumors also express RNA for HSD17B3 and
INSL3 (62).
Recently, Pihlajoki et al (64) described Sf1Cre;
Gata6flox/flox
mice, in which the Gata6 gene was deleted
using an Sf1Cre line of mice generated previously (63),
FVB-Tg(Nr5a1-cre)2Lowl/J) that differs from the Sf1Cre
mouse line used in this work (11). These animals had no
obvious testicular phenotype but developed small adrenal
glands with compromised steroidogenic adrenal function
(64). Interestingly, the adrenal glands of the Sf1Cre;
Gata6flox/flox
mice expressed gonadal-like transcripts,
such as Amhr2, Inha, Inhba, and Inhbb (64). Gonadec-
tomy of Sf1Cre; Gata6flox/flox
males led to an increase in
the adrenal expression of Amhr2, Lhcgr, and Cyp17 (64).
Taken together, these data suggest a role for GATA4 and
GATA6 in establishing and maintaining the characteristic
steroidogenic cell identities of gonads and adrenals.
Acknowledgments
Address all correspondence and requests for reprints to: Dr Ser-
gei G. Tevosian, Department of Physiological Sciences, College
of Veterinary Medicine, University of Florida, Gainesville, FL,
32610. E-mail: stevosian@ufl.edu.
Present address for D.A.M.: Department of Applied Physiol-
ogy and Kinesiology, College of Health and Human Perfor-
mance, University of Florida, Gainesville, FL, 32611.
This work was supported by the National Institutes of Health
Grant HD042751.
Disclosure Summary: The authors have nothing to disclose.
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