Cells derived from A-T individuals exhibit a variety of abnormalities in culture such as a higher requirement for serum factors, hypersensitivity to ionizing radiation and cytoskeletal defects.
Telomeric associations correlate with genomic instability and carcinogenicity.
There is growing evidence suggesting that both the shielding of telomeric ends and their elongation by telomerase are dependent upon telomere binding proteins. Mammalian telomeres are packaged in telomere specific chromatin. Human and mouse cell lines have their telomeric tracts attached to the nuclear matrix, which is a proteinaceous subnuclear fraction. There is a difference in nucleosomal organization of telomeres as compared to bulk DNA and telomeric histone H4 is hypoacetylated. Telomere length homeostasis in yeast requires the binding of a protein along the telomeric tract and changes in the telomeric matrix binding site occurs at least once in every kb of the telomeric tract in tumor derived cell lines.