a paper I presented on an exam. This is the presentation I prepared for it.

2. Extension of Life-Span by
Introduction of Telomerase
into Normal Human Cells
Andrea G.
Bodnar et al.
Science,
pp. 349-352,
vol. 279 (1998)
Podlevsky, J.D., Bley, C.J., Omana, R.V., Qi, X., Chen, J. (2007) The Telomerase Database. Nucleic Acids Res. 36 D339-D343.

3. Telomeres senescence theory

4. Telomeres senescence theory
Human telomeres (in yellow)

5. Telomeres senescence theory
- TTAGGG/CCCTAA
sequence
- Synthesized by the
ribonucleoprotein
enzyme telomerase
- Active in germline cells, keeps
telomeres at about 15 kpb
- Not expressed in most human
Human telomeres (in yellow) somatic tissues, where telomeres
lenghts is significantly shorter

6. Telomeres senescence theory
- TTAGGG/CCCTAA
sequence
- Synthesized by the
ribonucleoprotein
enzyme telomerase
- Active in germline cells, keeps
telomeres at about 15 kpb
- Not expressed in most human
Human telomeres (in yellow) somatic tissues, where telomeres
lenghts is significantly shorter
Theory proposes that cells become senescent
when progressive telomeres shortening during
each division produces a treshold telomere length

7. How telomerase works

8. How telomerase works

9. How telomerase works

10. How telomerase works

11. How telomerase works

12. Research...

13. Research...
- The hTRT has been cloned
- telomerase activity can be reconstituted by transient
expression of hTRT in norman human diploid cells
- hTR (template RNA component costituvely expressed)
- hTRT- normal cells transfected with
2 different hTRT expression constructs:

14. Research...
- The hTRT has been cloned
- telomerase activity can be reconstituted by transient
expression of hTRT in norman human diploid cells
- hTR (template RNA component costituvely expressed)
- hTRT- normal cells transfected with
2 different hTRT expression constructs:
#1
engineered by removal of the 5’ and 3’ untranslated
regions of hTRT and creation of Kozak consensus sequence

15. Research...
- The hTRT has been cloned
- telomerase activity can be reconstituted by transient
expression of hTRT in norman human diploid cells
- hTR (template RNA component costituvely expressed)
- hTRT- normal cells transfected with
2 different hTRT expression constructs:
#1
engineered by removal of the 5’ and 3’ untranslated
regions of hTRT and creation of Kozak consensus sequence
#2
native sequence cloned downstream of the SV40 promoter

16. Research...
- The hTRT has been cloned
- telomerase activity can be reconstituted by transient
expression of hTRT in norman human diploid cells
- hTR (template RNA component costituvely expressed)
- hTRT- normal cells transfected with
2 different hTRT expression constructs:
#1 comparison between life span of MPSV-hTRT
transfected cells and vector only transfected cells
#2
comparison of lifespan of activity positive and activity negative
stable clones containing SV40-hTRT constructs

17. Telomerase activity in stable
Retinal Pigment Epithelial cells

18. Telomerase activity in stable
Retinal Pigment Epithelial cells

19. Telomeres length in stable RPE and BJ clones

20. Telomeres length in stable RPE and BJ clones

21. Effects of telomerase expression on cell lifespan

22. Effects of telomerase expression on cell lifespan

23. Effects of telomerase expression on cell lifespan

24. Effects of telomerase expression on cell lifespan

25. Implications

26. Implications
Results indicate that telomere loss in the absence of
telomerase is the intrinsic timing mechanism that controls
the number of cell divisions prior to senescence
Very low level of telomerase activity are apparently
insufficient to prevent telomere shortening.
This is consistent with the observation that stem cells have
low but detectable telomerase activity, yet continue to
exhibit shortening of their telomeres throughout life
Promoter strength, structure of untranslated regions, site of
integration, levels of hTR and hTRT and telomere- or
telomerase-associated proteins in specific cell types are all
factors that may affect the functional level of telomerase

27. Ideas

28. Ideas
- against atrophy of skin through loss of extracellular matrix
homeostasis in dermal fibroblasts
- age-related macular degeneration of lipofuscin and down-
regulation of a neuronal survival factor in RPE cells
- atherosclerosis caused by loss of proliferative capacity and
overexpression of hypertensive and thrombotic factors in
endothelial cells
- replacing of tumor cell lines with cloned normal diploid cells
- production of normal or engineered biotechnology products
or gene therapy

29. Thank you for listening
Original paper DOI: 10.1126/science.279.5349.349
pdf version available at http://www.slideshare.net/ATMB