Modulation of expression of LDH isoenzymes in endothelial cells by laminin: implications for angiogenesis.
Endothelial cell (EC) matrix interaction is critical in angiogenesis. Although matrix components can regulate the process of angiogenesis by acting as a reservoir of various cytokines, it is not clear if extracellular matrix (ECM) can modulate the production and activity of angiogenic cytokines. Investigations were therefore carried out to study the influence of the basement membrane (BM) protein, laminin (Ln) on the activity of vascular endothelial growth factor (VEGF), the major angiogenic cytokine, using isolated human umbilical vein ECs (HUVECs) in culture. Analysis of the biochemical markers of angiogenesis confirmed proangiogenic effect of Ln. The levels of VEGF protein and mRNA were not different in cells maintained on Ln, collagen I or polylysine substrata. Chorioallantoic membrane assay using VEGF isolated from cell extracts however revealed that Ln increased its angiogenic potency. Immunoblotting and HPLC analysis showed considerable reduction in poly adenosyl ribosylation of VEGF associated with a significant decrease in the levels of NAD+, in cells maintained on Ln substrata. Further, a shift in the isoenzymic pattern of LDH towards the B rich forms and an upregulation of LDH B gene were observed in cells maintained on Ln. Ln modulates expression of LDH gene through alpha(6)beta(4) integrin mediated downstream signaling involving p38 mitogen activated protein kinases (MAPK) pathway. It thus appears that Ln can affect aerobic metabolism of ECs by modulating the expression of LDH isoenzymes resulting in a decrease in the level of NAD+ that can cause a reduction in the poly adenosyl ribosylation of VEGF altering its angiogenic potency.
Kumar
V B Sameer
VB
Department of Biochemistry, University of Kerala, Thiruvananthapuram, Kerala 695581, India.
Viji
R I
RI
Kiran
M S
MS
Sudhakaran
P R
PR
D000818:Animals; D002642:Chick Embryo; D049033:Chorioallantoic Membrane / Q000098:blood supply; D024042:Collagen Type I / Q000378:metabolism; D042783:Endothelial Cells / Q000201:enzymology*; D004730:Endothelium, Vascular / Q000166:cytology; D006801:Humans; D039161:Integrin alpha6beta4 / Q000378:metabolism; D007527:Isoenzymes / Q000502:physiology; D007770:L-Lactate Dehydrogenase / Q000502:physiology*; D007797:Laminin / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D018919:Neovascularization, Physiologic / Q000502:physiology*; D011107:Polylysine / Q000737:chemistry; D015398:Signal Transduction / Q000502:physiology; D014471:Umbilical Veins / Q000166:cytology; D042461:Vascular Endothelial Growth Factor A / Q000502:physiology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D024042:Collagen Type I; D039161:Integrin alpha6beta4; D007527:Isoenzymes; D007797:Laminin; D042461:Vascular Endothelial Growth Factor A; D009243:NAD; D011107:Polylysine; D007770:L-Lactate Dehydrogenase; C409667:lactate dehydrogenase 1; D048051:p38 Mitogen-Activated Protein Kinases