Document Detail

Telomerase and differentiation in multicellular organisms: turn it off, turn it on, and turn it off again.
MedLine Citation:
PMID:  11841477     Owner:  NLM     Status:  MEDLINE    
Telomerase is a ribonucleoprotein complex that catalyses the addition of TTAGGG repeats onto telomeres, repetitive DNA structures found at the ends of linear chromosomes. The majority of human somatic tissues do not display telomerase activity and undergo telomeric shortening with consecutive divisions. This telomeric shortening results in replicative senescence in vitro and likely in vivo. Telomerase activity is present in the vast majority of tumors, preventing telomeric shortening and thereby enabling indefinite cell divisions. Telomerase activity is regulated throughout human development, undergoing silencing in almost all organ systems from embryogenesis onwards. However, regulated telomerase activity is seen in basal/stem cell compartments of highly regenerative tissues, such as those of the immune system, skin, and intestine. Avian species display telomerase repression and telomeric shortening similar to that seen in humans. However, rodents retain telomerase-competency throughout their lifespan and have not been shown to display division-dependent telomere shortening. The regulation of telomerase activity in plants is less well understood, although early indications suggest ubiquitous competency. The aim of this review is to present current data regarding developmental regulation of telomerase in humans, mice, chickens and flowering plants. Differentiation, quiescence and telomerase activity regulation will then be addressed in three human representative tissue systems; blood, skin, and intestine. We will also highlight similarities, differences and misconceptions in the developing field of telomere and telomerase biology.
Nicholas R Forsyth; Woodring E Wright; Jerry W Shay
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Review    
Journal Detail:
Title:  Differentiation; research in biological diversity     Volume:  69     ISSN:  0301-4681     ISO Abbreviation:  Differentiation     Publication Date:  2002 Jan 
Date Detail:
Created Date:  2002-02-13     Completed Date:  2002-05-22     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0401650     Medline TA:  Differentiation     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  188-97     Citation Subset:  IM    
Department of Cell Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9039, USA.
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MeSH Terms
Arabidopsis / enzymology,  genetics
Cell Differentiation*
Cell Division
Epidermis / enzymology
Gene Expression Regulation, Developmental
Gene Expression Regulation, Enzymologic
Hematopoietic Stem Cells / enzymology
Intestinal Mucosa / enzymology
Nuclear Transfer Techniques
Telomerase / genetics,  metabolism*
Telomere / genetics
Reg. No./Substance:

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