engleski

Human chromosome 1 telomere behaviour in Mouse A9 cell line

Telomeres are specialized structures at the end of all eukaryotic chromosomes. Their role is to protect and stabilize genomes. They are repetitive sequences that interact with specific proteins forming telomere loop (T-loop) or linear end of the chromosome. It is critical for every single cell organism and immortal cell line to keep telomeres stable because their loss results in chromosomal aberrations, deletions and ultimately death through apoptosis. In order to determine whether telomere conformation is endogenous property of the chromosome or cell proteins background is crucial, we introduced human chromosome 1 in mouse A9 cells. We found A9 cells to have unstable telomeres among which 28% were not labeled in addition to permanently changing karyotype. Also, we followed telomere dynamics of human chromosome 1 as well as mouse chromosomes in this cell line using PNA-FISH and Southern analysis. Surprisingly, introduction of human chromosome 1 resulted in total and average telomere shortening, from ~10 kb to ~3kb, as it was demonstrated by Southern blot analysis, and percentage of unlabeled telomeres increased to 66.5%. All chromosomes, human and mouse followed these changes demonstrating that protein cell background is crucial for telomere conformation. We argue that such effect of human chromosome 1 is due to expression of some human proteins interfering with mouse proteins on telomeres.

human chromosome 1; A9 cell line

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