Regulation of the rate of human telomere shortening

描述(申请人提供)：我研究的长期目标是确定调节人类细胞端粒缩短的分子机制。由于线性染色体的DNA复制不完整，端粒长度随着细胞分裂而不断缩短。当端粒变短时，正常细胞停止分裂并衰老。癌细胞能够保持其端粒长度，并无限期分裂。降低正常细胞的端粒缩短率将延长细胞寿命，而增加癌细胞的端粒缩短率将加速癌细胞进入危机，进一步阻止癌症的发展。因此，探讨调节端粒缩短的分子机制对延长正常细胞的功能寿命和癌症治疗都具有重要意义。该研究提案的具体目的是：(I)测量正常人类二倍体细胞和端粒酶阳性细胞中领先和滞后链上端粒突出的大小。(Ii)通过在体内直接测量Okazaki片段大小和使用体外DNA复制系统来确定Okazaki片段大小对端粒缩短率的贡献；(Iii)使用体外线性DNA复制系统来研究端粒末端复制问题。

DESCRIPTION (provided by applicant): The long-term objectives of my research are to determine the molecular mechanism regulating telomere shortening in human cells. Due to incomplete DNA replication of linear chromosomes, telomere length continuously shortens as cell divides. Normal cells stop dividing and reach senescence when telomeres are short. Cancer cells are able to maintain their telomere length and divide indefinitely. Decreasing the rate of telomere shortening in normal cells would increase cell life span, while increasing this rate in cancer cells would accelerate cancer cells going into crisis and further stop cancer progression. Therefore, exploring the molecular mechanisms regulating telomere shortening will have major impacts on both extending the functional life span of normal cells and cancer therapy. The specific aims of the research proposal are: (i) to measure the size of telomere overhang at leading and lagging strands in normal human diploid cells and telomerase-positive cells. (ii) to determine the contribution of Okazaki fragment size to telomere shortening rate by directly measuring Okazaki fragment size in vivo and using in vitro DNA replication system respectively; (iii) to investigate the telomere end-replication problem using an in vitro linear DNA replication system.