Age-related changes in the mRNA expression of actin isoforms in Drosophila melanogaster.

In all organisms the process of aging is characterized by a gradual loss of homeostatic maintenance functions and physiological fitness. This might be caused-in part-by a down-regulation of important housekeeping and maintenance genes. In our previous work we have shown that in Drosophila melanogaster aging is accompanied by a decrease in steady-state levels of most RNA species. This includes structural genes and housekeeping genes, though at a different level. Here we have examined age-related changes in the mRNA levels of the gene family encoding the six Drosophila actin genes. Two actin isoforms code for cytoskeletal actins and represent housekeeping genes, whereas the four muscle actin genes are expressed tissue-specifically in differentiated muscles. The results suggest that the six actin genes are differentially regulated during aging as well. The two cytoskeletal actin genes show little changes in their steady-state mRNA levels. Drastic changes are observed, however, in the mRNAs coding for muscle actins, particularly the mRNAs coding for the jump and flight muscle actins.