Telomere length changes during genome-wide epigenetic reprogramming in human preimplantation embryos

Area of Science:

• Developmental Biology
• Epigenetics
• Genetics

Background:

• Telomeres protect chromosome ends and shorten with cell division.
• Preimplantation development involves significant epigenetic reprogramming.
• Understanding telomere dynamics during this period is crucial for developmental insights.

Purpose of the Study:

• To investigate telomere length (TL) changes in human embryos during preimplantation development.
• To analyze parent-specific telomere inheritance and equalization.
• To explore the relationship between TL dynamics and epigenetic reprogramming.

Main Methods:

• Semiquantitative fluorescence in situ hybridization (FISH) was used.
• Relative TLs were measured in metaphase chromosomes of 69 human preimplantation embryos.
• Stages analyzed ranged from zygote to blastocyst.

Main Results:

• Relative TLs increased from zygote to 2-5-cell stage, then decreased by the blastocyst stage.
• Interindividual TL variability increased at the blastocyst stage.
• Parent-specific telomeres (paternal longer than maternal) were observed up to the 2-5-cell stage, followed by equalization.

Conclusions:

• Telomeres are reprogrammed alongside genome-wide epigenetic reprogramming in human embryos.
• Parent-specific TLs are fully reprogrammed by the blastocyst stage.
• Each embryo establishes a unique TL pattern by the blastocyst stage.