Telomere uncapping during in vitro T-lymphocyte senescence

Area of Science:

• Cellular senescence
• Telomere biology
• Immunosenescence

Background:

• Normal lymphocytes can activate telomerase upon stimulation.
• Repeated stimulation of lymphocytes in culture leads to senescence, telomere shortening, and reduced telomerase activity.
• Telomere uncapping is a known trigger for cellular senescence.

Purpose of the Study:

• To investigate the mechanisms of telomere dysfunction and senescence in lymphocytes during long-term culture and stimulation.
• To explore the role of shelterin gene expression in lymphocyte senescence.

Main Methods:

• Long-term culture and repeated stimulation of lymphocytes.
• Analysis of telomere length dynamics.
• Assessment of DNA damage markers (gamma-H2AX, 53BP1 foci).
• Quantification of shelterin gene expression.

Main Results:

• Lymphocyte stimulation induced telomere shortening, preferentially at long telomeres, with transient increases after each stimulation.
• Increased DNA damage foci at telomeres (gamma-H2AX, 53BP1) were observed, correlating with p16(ink4a) increase.
• Expression of key shelterin genes (hTRF1, hTANK1, hTIN2, hPOT1, hRAP1) decreased with each stimulation.

Conclusions:

• Lymphocyte senescence under iterative stimulation involves both excessive telomere shortening and reduced shelterin gene expression.
• Telomere dysfunction in aging T-cells is influenced by shelterin complex integrity.
• Findings have implications for understanding T-cell biology and the aging process.