Telomeres, Reproductive Aging, and Genomic Instability During Early Development

Area of Science:

• Reproductive biology
• Molecular genetics
• Cellular aging

Background:

• Advancing maternal age is associated with decreased implantation rates and increased miscarriage.
• Oocyte aging is a primary driver of reproductive aging, as demonstrated by successful oocyte donation studies.
• Previous research indicates that the nucleus, not the cytoplasm, carries the reproductive aging phenotype.

Purpose of the Study:

• To investigate telomere attrition as a unifying mechanism for oocyte aging.
• To explore the role of telomere length and telomere maintenance mechanisms in reproductive decline.
• To examine the implications of alternative lengthening of telomeres (ALT) in early embryonic development.

Main Methods:

• Utilized a mouse model of reproductive aging with experimentally shortened telomeres.
• Analyzed telomere length in polar bodies to predict human embryo fragmentation.
• Investigated telomere elongation mechanisms, including ALT, in oocytes and preimplantation embryos.

Main Results:

• Experimental telomere shortening replicated reproductive aging phenotypes in mice, including meiotic errors and embryo fragmentation.
• Telomere length in polar bodies correlated with human embryo fragmentation.
• Telomeres elongate via ALT in early embryonic cell cycles, a mechanism previously observed mainly in cancer cells.

Conclusions:

• Telomere attrition is a significant contributor to oocyte aging and associated reproductive decline.
• Alternative lengthening of telomeres (ALT) may elongate telomeres across generations but introduces genomic instability in preimplantation embryos.
• Understanding telomere dynamics is crucial for addressing age-related fertility issues.