The+relationships+between+immortal+cells&aging+process

All normal body cells undergo senescence and aging before their death through apoptosis. [3] The abnormal behavior of the enzyme B- galactosidase was linked to senescent cells. [3] The optimal activity of the enzyme occurs at the pH 4 however, in senescent cells its optimal activity is at pH 6. [3][5] The number of cells positive for the enzyme increases with age and the culmulative population doublings. [3] However, immortal cells related to telomeres do not undergo any process of aging. [1][4] For survival and proliferation of cells, the integrity of telomere is critical. [1][2][4] Telomeres are "nucleoprotein structures loacated at the linear ends of eukaryotic chromosomes". [1] Telomere shortening has been linked to onset of senescence in human cells. [3] Short dysfuctional telomeres, are usually perceived as damaged DNA and may activate p53 and pRb pathways causing senescence in human cells. [3] Yet, inactivation of these pathways usually leads to extended life span of cells with out immortalising the involved cells. [5] This is observed in HeLa tumor cells where the number of cells with B-galactosidase enzyme does not correlate with culmulative population doublings. [3] While normal cells divided 45-50times on overage before rapidly undergoing senescence and possible apoptotic cell death, immortal cells divide indefinitely without aging and death. [1][6] This is because they have deactivated their own senescence genes. [1] The aging process is multifaceted and telomere biology is inadequate in explaining the complete aging process. Nevertheless, telomere regulation can give a clue on vulnerability of aging. [6]
 * The relationship between immortal body cells and aging process:**

By YongMin KIM //Last edited 11/11/2011//


 * References:**

[1] Chen X., F.; Meng F.., L.; Zhou J., Q. (2009) Telomere Recombination Accelerates Cellular Aging in //Saccharomyces cerevisiae.// PLoS Genet, Vol. 5(6): e1000535 Doi:10.1371/journal.pgen.1000535.

[2] Chung, D. C. (2010). //The Massachusetts General Hospital Guide to Clinical Cancer Genetics.// Boston, USA: Springer. pp. 15-17.

[3] De Magalhaes, J. P. (2008). //Cellular Senescence//. Availiable: []. [2011, 7/11/2011].

[4] Freed, W. J. (2000). //Neural transplantation: an introduction: Cellular and molecular// //neuroscience series.// USA: MIT Press.

[5] Sharma, H. W., Sokoloski, J. A., Perez, J. R., Maltese, J. Y., Sartorelli, A. C., Stein, C. A., et al. (1995). Differerentiation of immortal cells inhibits telomerase activity. //Proc. Natl. Acad.// //Sci. USA// //92//, Vol. 92 pp, 12343-12346.

[6] Vaziri, H., & Benchimol, S. (1999). Alternative pathways for the extension of cellular life span: inactivation of p53/pRb and expression of telomerase. //Oncogene//, Vol. 18(53): 7676-7680.