Analysis of telomere length in the aged mdx diaphragm with and without transgenic IGF-I expression

摘要

Chromosomal telomere length can help to indicate of the number of divisions a somatic cell has undergone. Telomere length was assessed in diaphragm muscles from mdx mice and mdx mice expressing high levels of insulin-like growth factor I (mdx:mIgf+/+) to test if the hypertrophy and hyperplasia observed in the mdx:mIgf+/+ diaphragm was associated with increased satellite cell division and a detectable change in telomere length. Southern blotting of digested genomic DNA was performed using a probe for telomeric repeats. DNA from young and aged mdx and aged mdx:mIgf+/+ diaphragms displayed similar patterns of telomere repeat fragments. Therefore, no difference in number of satellite cell divisions could be detected. We postulate that inherently long telomere length and telomerase activity which are present in murine muscle obscure the telomere length measurement even when high levels of muscle regeneration exist. Therefore, the effect of IGF-I on cell replicative age will need to be determined in a species without telomerase, such as the canine model for muscular dystrophy.haper