extension of life-span by introduction of telomerase into normal human cells
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a paper I presented on an exam. This is the presentation I prepared for it.TRANSCRIPT
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.
Telomeres senescence theory
Telomeres senescence theory
Human telomeres (in yellow)
Telomeres senescence theory
Human telomeres (in yellow)
- TTAGGG/CCCTAA sequence- Synthesized by theribonucleoproteinenzyme telomerase- Active in germline cells, keeps telomeres at about 15 kpb
- Not expressed in most human somatic tissues, where telomeres lenghts is significantly shorter
Telomeres senescence theory
Human telomeres (in yellow)
- TTAGGG/CCCTAA sequence- Synthesized by theribonucleoproteinenzyme telomerase- Active in germline cells, keeps telomeres at about 15 kpb
- Not expressed in most human 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
How telomerase works
How telomerase works
How telomerase works
How telomerase works
How telomerase works
Research...
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 with2 different hTRT expression constructs:
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 with2 different hTRT expression constructs:
#1engineered by removal of the 5’ and 3’ untranslatedregions of hTRT and creation of Kozak consensus sequence
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 with2 different hTRT expression constructs:
#1#2
engineered by removal of the 5’ and 3’ untranslatedregions of hTRT and creation of Kozak consensus sequence
native sequence cloned downstream of the SV40 promoter
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 with2 different hTRT expression constructs:
#1#2
comparison between life span of MPSV-hTRTtransfected cells and vector only transfected cells
comparison of lifespan of activity positive and activity negative stable clones containing SV40-hTRT constructs
Telomerase activity in stable Retinal Pigment Epithelial cells
Telomerase activity in stable Retinal Pigment Epithelial cells
Telomeres length in stable RPE and BJ clones
Telomeres length in stable RPE and BJ clones
Effects of telomerase expression on cell lifespan
Effects of telomerase expression on cell lifespan
Effects of telomerase expression on cell lifespan
Effects of telomerase expression on cell lifespan
Implications
ImplicationsResults 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
Ideas
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
Thank you for listening
Original paper DOI: 10.1126/science.279.5349.349
pdf version available at http://www.slideshare.net/ATMB