A Role for Nuclear Phospholipase Cβ1 in Cell Cycle Control*

By I. Faenza, A. Matteucci, L. Manzoli, A. Billi, M. Aluigi, D. Peruzzi, M. Vitale, S. Castorina, P. Suh, L. Cocco. Journal of Biological Chemistry, 2000

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Phosphoinositide signaling resides in the nucleus, and among the enzymes of the cycle, phospholipase C (PLC) appears as the key element both in Saccharomyces cerevisiaeand in mammalian cells. The yeast PLC pathway produces multiple inositol polyphosphates that modulate distinct nuclear processes. The mammalian PLCβ1, which localizes in the nucleus, is activated in insulin-like growth factor 1-mediated mitogenesis and undergoes down-regulation during murine erythroleukemia differentiation. PLCβ1 exists as two polypeptides of 150 and 140 kDa generated from a single gene by alternative RNA splicing, both of them containing in the COOH-terminal tail a cluster of lysine residues responsible for nuclear localization. These clues prompted us to try to establish the critical nuclear target(s) of PLCβ1 subtypes in the control of cell cycle progression. The results reveal that the two subtypes of PLCβ1 that localize in the nucleus induce cell cycle progression in Friend erythroleukemia cells. In fact when they are overexpressed in the nucleus, cyclin D3, along with its kinase (cdk4) but not cyclin E is overexpressed even though cells are serum-starved. As a consequence of this enforced expression, retinoblastoma protein is phosphorylated and E2F-1 transcription factor is activated as well. On the whole the results reveal a direct effect of nuclear PLCβ1 signaling in G1 progression by means of a specific target, i.e. cyclin D3/cdk4.

Subfields: Molecular Biology, Oncology

View Paper: https://www.semanticscholar.org/paper/a925588a3f4f9df5c48b6cacc3ffe627627c1166