Linking phospholipase C isoforms with differentiation function in human vascular smooth muscle cells.
Louise S Mackenzie1, Joanne S Lymn2, Alun D Hughes3
1Department 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.
Biochimica Et Biophysica Acta
|August 20, 2013
Summary
Phosphoinositol-phospholipase C (PLC) delta 1 is the main enzyme in vascular smooth muscle cells. PLC delta 1 levels change with cell cycle and differentiation, impacting cell function.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- The phosphoinositol-phospholipase C (PLC) enzyme family has multiple isoforms with distinct cellular roles.
- PLCγ1 is linked to tyrosine kinase pathways, while PLCδ1 is associated with cell cycle regulation.
- Understanding specific PLC isoform functions is crucial for defining cellular responses.
Purpose of the Study:
- To investigate differences in PLC isoform expression and activity in human and rat vascular smooth muscle cells.
- To determine the role of PLC isoforms in vascular smooth muscle cell differentiation and contractile function.
Main Methods:
- Western blotting was used to analyze PLC isoform levels.
- PLC activity assays were performed.
- Human vascular smooth muscle cells (HVSMCs) were subjected to growth arrest via serum deprivation.
- Rat mesenteric arteries were cultured in serum-free media (SFM) to model de-differentiation.
Main Results:
- PLCδ1 and PLCγ1 were identified as the predominant isoforms in cycling HVSMCs.
- Serum deprivation led to increased PLCδ1 and SM α-actin in HVSMCs, with no change in PLCγ1.
- De-differentiation of rat mesenteric arteries resulted in decreased contractility, contractile proteins, and PLCδ1, but not PLCγ1.
Conclusions:
- PLCδ1 is the predominant PLC isoform in vascular smooth muscle.
- PLCδ1 expression is significantly influenced by factors affecting the cell cycle and differentiation status.
- PLCδ1 plays a key role in maintaining vascular smooth muscle contractile function.
Related Concept Videos
01:42Phosphoinositides and PIPs
Phosphoinositides are a group of phospholipids containing a glycerol backbone with two fatty acid chains and a phosphate attached to a myoinositol sugar ring. The inositol head group extends into the cytoplasm, where it is modified by adding phosphate groups to form phosphatidylinositol phosphates or PIPs.
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
01:11IP3/DAG Signaling Pathway
Membrane lipids such as phosphatidylinositol (PI) are precursors for several membrane-bound and soluble second messengers. Specific kinases phosphorylate PI and produce phosphorylated inositol phospholipids. One such inositol phospholipids are the phosphatidylinositol-4,5 bisphosphate [PI(4,5)P2], present in the inner half of the lipid bilayer. Upon ligand binding, GPCR stimulates Gq proteins to turn on phospholipase Cꞵ. Activated phospholipase Cꞵ cleaves PI(4,5)P2 and produces two-second...
01:35Asymmetric Lipid Bilayer
Biological membranes show uneven distribution of different types of lipids in the inner and outer layers, resulting in transverse asymmetric membranes. The treatment of the erythrocyte membrane with the enzyme phospholipase confirmed the asymmetric nature of the lipid bilayer. The enzyme hydrolyzes lipids into fatty acids and hydrophilic groups. The phospholipase acts only on the outer layer of the membrane, while the inner layer remains intact. The phospholipase treatment resulted in 80%...
01:15Amplifying Signals via Second Messengers
Many receptor binding ligands are hydrophilic; they do not cross the cell membrane but bind to cell-surface receptors. Thus, their message must be relayed by second messengers present in the cell cytoplasm. There are several second messenger pathways, each with its own way of relaying information. For example, the G protein-coupled receptors can activate both phosphoinositol and cyclic AMP (cAMP) second messenger pathways. The phosphoinositol pathway is active when the receptor induces...
01:19Membrane Asymmetry Regulating Transporters
Enzymes like flippase, floppase, and scramblase transfer phospholipids from one layer to another in the membrane, thereby affecting membrane asymmetry.
Flippase
Eukaryotic flippases are type-IV P-type ATPases or P4-ATPases belonging to P-type ATPase family proteins that are membrane-bound pumps involved in the ATP-mediated transport of ions and molecules across the membrane. Flippases flip specific phospholipids from the outer to the inner leaflet of a membrane. All P4-ATPases have one...
Flippase
Eukaryotic flippases are type-IV P-type ATPases or P4-ATPases belonging to P-type ATPase family proteins that are membrane-bound pumps involved in the ATP-mediated transport of ions and molecules across the membrane. Flippases flip specific phospholipids from the outer to the inner leaflet of a membrane. All P4-ATPases have one...
01:16Calmodulin-dependent Signaling
Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change.
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...