mRNA expression of two transmembrane protein tyrosine phosphatases is modulated by growth factors and growth arrest in 3T3 fibroblasts.

Changes in mRNA expression are physiological regulatory mechanisms and frequently deliver important information regarding functions of corresponding gene products. We investigated changes of abundantly expressed mRNAs of two transmembrane protein tyrosine phosphatases, LRP (leukocyte common antigen-related phosphatase) and mRPTP-sigma. The LRP mRNA expression was modulated by platelet derived growth factor (PDGF) treatment and seems to be regulated by PDGF receptor kinase. The expression of mRPTP-sigma mRNA was low in actively cycling cells, like those in the exponential phase of growth or those treated with different growth factors. In cells whose growth was arrested by contact inhibition at high cell density or by serum starvation at low cell density mRPTP-sigma mRNA level increased. The possible implications of these mRNA expression patterns are discussed.