Identification of phospholipase C b isoforms and their location in cultured vascular smooth muscle cells of pig, human and rat. Cardiovasc Res

Objectives: Four phospholipase C (PLC) b isoforms have been described in pig aortic vascular smooth muscle. The aim was to determine if all four PLC b isoforms are commonly expressed in vascular smooth muscle cells (VSMC) of three species, i.e. pig, human and rat, and if the individual isoforms had distinctive intracellular distributions. Methods: Vascular smooth muscle cell cultures were derived from explants of porcine and rat aorta and a human renal artery cell line. PLC b isoform content was resolved using Western blotting. Intracellular location was determined by immunocytochemistry and confocal microscopy. Results: All three species expressed PLCs b, b, b and b. In all species, PLC b demonstrated foci of concentration throughout the cytoplasm; PLC b demonstrated a1 2 3 4 1 2 punctate pattern that was principally at the cell periphery or was in the Golgi, depending upon the antibody used; PLC b was also3 cytoplasmic but showed a different pattern from PLC b and PLC b was cytoplasmic, except in pig quiescent cells, where it was1 4 associated with filamentous structures at the intersection with the plasma membrane. Conclusions: VSMCs of three different species express all four PLC b isoforms. Each isoform has a unique and consistent signature of distribution that is generally common to al