Identification of phospholipase C beta isoforms and their location in cultured vascular smooth muscle cells of pig, human and rat

Objectives: Four phospholipase C (PLC) beta isoforms have been described in pig aortic vascular smooth muscle. The aim was to determine if all four PL C beta isoforms are commonly expressed in vascular smooth muscle cells (VSM C) of three species, i.e. pig, human and rat, and if the individual isoform s had distinctive intracellular distributions. Methods: Vascular smooth mus cle cell cultures were derived from explants of porcine and rat aorta and a human renal artery cell line. PLC beta isoform content was resolved using Western blotting. Intracellular location was determined by immunocytochemis try and confocal microscopy. Results: All three species expressed PLCs beta (1), beta(2), beta(3) and beta(4). In all species, PLC beta(1) demonstrated foci of concentration throughout the cytoplasm; PLC beta(2) demonstrated a punctate pattern that was principally at the cell periphery or was in the Golgi, depending upon the antibody used; PLC beta(3) was, also cytoplasmic but showed a different pattern from PLC beta(1) and PLC beta(4) was cytopla smic, except in pig quiescent cells, where it was associated with filamento us structures at the intersection with the plasma membrane. Conclusions: VS MCs of three different species express all four PLC beta isoforms. Each iso form has a unique and consistent signature of distribution that is generall y common to all species. (C) 1998 Elsevier Science BN. All rights reserved.