Enhanced expression of HMG-Y proteins in proliferating tissues.

The high mobility group (HMG) proteins I and Y are well characterised non-histone chromosomal proteins which bind to A-T rich regions of DNA and regulate gene expression and/or DNA replication. A correlation has been demonstrated between the increased expression of HMG-Y proteins and malignancy. However, it is not known whether the expression of HMGs particularly, the Y group, is a function of proliferation rate. In the present study, we have used normal tissues of calf testes, thymus and liver. The results show distinctly high expression of HMG-Y proteins in testes than in thymus and the expression was practically undetectable in liver. The results suggest that even in normal tissues there is a direct correlation between the proliferation rate and the expression of the HMG-Y proteins, which can partly explain its increased expression in cancer.