SHP-1 regulates transcription of PCK1 to control gluconeogenesis

The protein-tyrosine phosphatase SHP-1 (PTPN6) is an important glucose homeostasis modulator. Besides negatively regulating insulin signaling, the specific role of SHP-1 in metabolic control remains poorly understood. We show that SHP-1 acts as a co-activator for transcription of the phosphoenolpyruvate carboxykinase 1 (PCK1) gene, thereby modulating basal gluconeogenesis in hepatocytes. SHP-1 interacts with RNA polymerase II-subunits and signal transducer and activator of transcription 5 (STAT5), and localizes to the nucleus, where a sub-fraction of SHP-1 associates with chromatin. While SHP-1 binds to the PCK1-promoter, its loss affects RNA polymerase II-recruitment to this and other promoters of genes enriched for glucose metabolism-related functions. SHP-1-downregulation, and similarly STAT5 pharmacological inhibition reduce PCK1-transcript levels correlating with blunted gluconeogenesis. Overall, we identified a novel molecular SHP-1-function, that of a regulator of PCK1-transcription and subsequently hepatic gluconeogenesis, through physical interaction with the transcription machinery, mediated by an Akt-independent mechanism, but independent of STAT5 tyrosine-phosphorylation status. Overall design: ChIP-seq analysis of HepG2 SHP-1-WT (CRISPR control) and SHP-1-KO (CRISPR KO) cells. Antibodies used: anti-Rpb1 (anti-RNAPII-CTD) and anti-Rpb1-pSer2 (anti-RNAPII-CTD-pSer2)