Phosphorylation of Pit-1 by cyclin-dependent kinase 5 at serine 126 is associated with cell proliferation and poor prognosis in prolactinomas

Abstract Pit-1 (POU1F1) is a POU-homeodomain transcription factor, and it one of the most important tissue-specific factors in pituitary development. Cyclin-dependent kinase 5 (CDK5) protein that can phosphorylate many key factors, but mechanism under which CDK5 phosphorylates unclear. To investigate whether regulate cell proliferation promote hormone secretion through phosphorylation Ser126-Pit-1 prolactinomas, we generated an antibody specifically recognizes phosphorylated serine at position 126 (Ser126-Pit-1). We used western blotting to detect level observed apoptosis GH3 cells with different levels by clone formation experiments, viability assays, flow cytometry. ELISA was measure PRL supernatant cells. Tissue microarrays immunohistochemistry were evaluate expression (pSer126-Pit-1) prolactinomas. Our data indicated high-level pSer-126-Pit-1 secretion. In addition, higher correlates worse prognosis patients prolactinoma. results show mediated regulated prolactinoma progression