Protein Tyrosine Phosphatase Non-receptor 3 Acts as a Tumor Suppressor and Boosts TGF-b Signaling Independent of its Phosphatase Activity

Transforming Growth Factor b (TGF-b) controls a variety of cellular functions during development. Abnormal TGF-b responses are commonly found in human diseases such as cancer, suggesting that TGF-b signaling must be tightly regulated. Here we report that Protein Tyrosine Phosphatase Non-receptor 3 (PTPN3) profoundly potentiates TGF-b signaling independent of its phosphatase activity. PTPN3 stabilizes TGF-b type I receptor (TbRI) through attenuating the interaction between Smurf2 and TbRI. Consequently, PTPN3 facilitates TGF-b-induced R-Smad phosphorylation, transcriptional responses and subsequent physiological responses. Importantly, the leucine-to-arginine substitution at amino acid residue 232 (L232R) of PTPN3, a frequent mutation found in intrahepatic cholangiocarcinoma (ICC), disable the role to enhance TGF-b signaling and abolishes its tumor suppressive function. Our findings have revealed a vital role of PTPN3 in regulating TGF-b signaling during normal physiology and pathogenesis. mRNA profiles of HaCaT siControl and siPTPN3 cells with or without TGF-beta were generated by deep sequencing, using Illumina HiSeq X Ten. There are four samples for transcriptome sequencing (RNA-Seq).