Abstract
The expression of chromosomal proteins HMG-14 and HMG-17 during cellular differentiation was studied in cultured mouse myoblasts. During myogenesis the level of both HMG-14 and HMG-17 mRNA decreased to less than 20% of that found in myoblasts. The down-regulation of HMG-14/-17 mRNA occurred simultaneously with activation of muscle-specific actin mRNA and was not linked to DNA synthesis, indicating that it is a differentiation-, rather than a cell cycle-related event. Incorporation of radiolabeled lysine into HMG proteins was similar to that into the major histone fractions in that it was significant in myoblasts and undetectable in myotubes. The decrease in mRNA and protein synthesis did not affect the cellular levels of HMG protein. These results indicate that the regulation of HMG-14/-17 mRNA levels is different from that of the histones and is linked to differentiation rather than to DNA synthesis.
Highlights
The expression of chromosomal proteins HMG-14 and HMG- 17 during cellular differentiation was studied in cultured mouse myoblasts
During myogenesis the level of both HMG-14 and HMG-17 mRNA decreased to less than 20% of that found in myoblasts
Expression of HMG-141-17 during Myogenesis esis were monitored by pulse labeling with radioactive precursors
Summary
The expression of chromosomal proteins HMG-14 and HMG- 17 during cellular differentiation was studied in cultured mouse myoblasts. The results indicate that during myogenesis both the mRNA levels and protein synthesis rate decrease without a significant alteration in the cellular protein concentration. Interruption of DNA synthesis with hydroxyurea resulted in immediate down-regulation of histone mRNA levels without having any effect on HMG synthesis, indicating that the expression of these two classes of nucleosomal proteins are independently regulated.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have