Inhibition of PID1/NYGGF4/PCLI1 gene expression highlights its role in the early events of the cell cycle in NIH3T3 fibroblasts.

ThePID1/NYGGF4/PCLI1gene encodes for a protein with a phosphotyrosine-binding domain, which interacts with the lipoprotein receptor-related protein 1. Previous work by us and others suggested a function of the gene in cell proliferation of NIH3T3 fibroblasts and 3T3-L1 pre-adipocytes. The molecular characterization of PCLI1 protein, ectopically expressed in NIH3T3 fibroblasts, revealed two phosphorylation sites at Ser154 and Ser165. In order to clarify the functions of this gene, we analyzed the effects of its downregulation on cellular proliferation and cell cycle progression in NIH3T3 cell cultures. Downregulation ofPID1/NYGGF4/PCLI1mRNA levels by short hairpin RNAs (shRNAs) elicited decreased proliferation rate in mammalian cell lines; cell cycle analysis of serum-starved, synchronized NIH3T3 fibroblasts showed an increased accumulation of shRNA-interfered cells in the G1 phase. Decreased levels ofFOSandMYCmRNAs were accordingly associated with these events. The molecularscenarioemerging from our data suggests thatPID1/NYGGF4/PCLI1controls cellular proliferation and cell cycle progression in NIH3T3 cells. [ABSTRACT FROM PUBLISHER]