title: Linking phospholipase C isoforms with differentiation function in human vascular smooth muscle cells.
abstract: The phosphoinositol-phospholipase C (PLC) family of enzymes consists of a number of isoforms, each of which has different cellular functions. PLCγ1 is primarily linked to tyrosine kinase transduction pathways, whereas PLCδ1 has been associated with a number of regulatory proteins, including those controlling the cell cycle. Recent studies have shown a central role of PLC in cell organisation and in regulating a wide array of cellular responses. It is of importance to define the precise role of each isoform, and how this changes the functional outcome of the cell. Here we investigated differences in PLC isoform levels and activity in relation to differentiation of human and rat vascular smooth muscle cells. Using Western blotting and PLC activity assay, we show that PLCδ1 and PLCγ1 are the predominant isoforms in randomly cycling human vascular smooth muscle cells (HVSMCs). Growth arrest of HVSMCs for seven days of serum deprivation was consistently associated with increases in PLCδ1 and SM α-actin, whereas there were no changes in PLCγ1 immuno-reactivity. Organ culture of rat mesenteric arteries in serum free media (SFM), a model of de-differentiation, led to a loss of contractility as well as a loss of contractile proteins (SM α-actin and calponin) and PLCδ1, and no change in PLCγ1 immuno-reactivity. Taken together, these data indicate that PLCδ1 is the predominant PLC isoform in vascular smooth muscle, and confirm that PLCδ1 expression is affected by conditions that affect the cell cycle, differentiation status and contractile function.
authors: Department of Pharmacology, School of Life and Medical Sciences, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK; Department of Clinical Pharmacology, National Heart & Lung Institute, Imperial College London, QEQM Wing, St. Mary's Hospital, Paddington, London W2 1NY, UK. Electronic address: l.mackenzie2@herts.ac.uk.
authors: Louise S
authors: LS
authors: Mackenzie
authors: Department of Clinical Pharmacology, National Heart & Lung Institute, Imperial College London, QEQM Wing, St. Mary's Hospital, Paddington, London W2 1NY, UK; Institute of Cell Signalling, The School of Health Sciences, The University of Nottingham, Queens Medical Centre, Nottingham NG7 2UH, UK.
authors: Joanne S
authors: JS
authors: Lymn
authors: Department of Clinical Pharmacology, National Heart & Lung Institute, Imperial College London, QEQM Wing, St. Mary's Hospital, Paddington, London W2 1NY, UK.
authors: Alun D
authors: AD
authors: Hughes
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D004247:DNA / Q000096:biosynthesis; D004261:DNA Replication / Q000187:drug effects; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects / Q000502:physiology; D018613:Microscopy, Confocal; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D032389:Myocytes, Smooth Muscle / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D009924:Organ Culture Techniques; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D010738:Type C Phospholipases / Q000378:metabolism*
chemical_list: D016895:Culture Media, Serum-Free; D007527:Isoenzymes; D004247:DNA; D010738:Type C Phospholipases
keywords: Actin; Cytoskeleton; Differentiation; HVSMCs; Human vascular smooth muscle; PLC; Phosphoinositol-phospholipase C; RC; SFM; human vascular smooth muscle cells; phosphoinositol-phospholipase C; randomly cycling; serum free media