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.

In silico modelling of prostacyclin and other lipid mediators to nuclear receptors reveal novel thyroid hormone receptor antagonist properties

“…First and second order mesenteric arteries were removed and prepared as described previously [14]. Briefly, artery segments were dissected in Kreb's buffer (pH 7.4, 1.18 × 10 −3 mol/L NaCl, 4.7 × 10 −3 mol/L KCl, 1.2 × 10 −3 mol/L MgSO 4 , 1.2 × 10 −3 mol/L KH 2 PO 4 , 2.5 × 10 −3 mol/L CaCl 2 , 2.5 × 10 −2 mol/L NaHCO 3 and 1.1 × 10 −2 mol/L glucose), and loaded onto isometric wire myographs.…”

Phylogenetic and structural analysis of the phospholipase A2 gene family in vertebrates

“…This gene family is classified into four major classes, namely, phospholipase PLA, PLB, PLC and PLD ( 1 ), based on the types of catalytic reaction of phospholipids. The majority of coding enzymes play crucial roles in lipid metabolism ( 2 ), cell proliferation ( 3 ), muscle contraction ( 4 - 6 ) and in the inflammation process ( 5 ). The PLA class includes two subfamilies, namely PLA1 and PLA2.…”

Phospholipase Cγ1 Mediates Intima Formation Through Akt‐Notch1 Signaling Independent of the Phospholipase Activity

“…This discrepancy could be explained by the fact that, besides PLCγ1, U73122 could moderately inhibit other members of the PLC family . For example, PLCδ1, another PI‐PLC, is also highly expressed in VSMCs . Ideally, cell‐specific PLCγ1 inhibitors are needed.…”

“…However, the physiological function of PLCγ1 has not been well established, especially in vivo . U73122 can inhibit the catalytic activity of PLC, and then inhibit ERK1/2 activation and cell proliferation in VSMCs . However, U73122 is not specific to PLCγ1 .…”