Thyroid cell transformation inhibits the expression of a novel rat protein tyrosine phosphatase.

We have isolated a rat thyroid cDNA encoding a novel rat receptor-type tyrosine phosphatase protein. This gene, on the basis of its homology to another tyrosine phosphatase, the recently isolated human DEP-1/HPTPeta, has been named r-PTPeta. In rat thyroid cells the r-PTPeta gene acts as a differentiation marker. Indeed, the block of thyroid cell differentiation induced by viral and cellular oncogenes is associated with the inhibition or marked reduction of the expression of this gene, and its expression is positively regulated by thyrotropin, the physiological stimulator of thyroid cell growth.