Endothelial cell-laminin interaction: modulation of LDH expression involves alpha6beta4 integrin-FAK-p38MAPK pathway

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Angiogenesis, the formation of new blood vessels, is crucial for development and disease.
• Laminin (Ln) is a key extracellular matrix protein implicated in cell adhesion and signaling.
• The precise molecular mechanisms by which laminin influences angiogenic processes are under investigation.

Purpose of the Study:

• To elucidate the molecular mechanisms underlying the angiogenic effects of laminin.
• To investigate the role of poly ADP-ribosylation (PAR) and vascular endothelial growth factor (VEGF) in laminin-mediated angiogenesis.
• To identify the specific signaling pathways involved in laminin's effects on endothelial cells.

Main Methods:

• Human Umbilical Vein Endothelial Cells (HUVECs) were cultured on laminin.
• Poly ADP-ribosylation (PAR) of VEGF was assessed.
• Changes in NAD(+) levels and lactate dehydrogenase (LDH) isoenzyme shifts were analyzed.
• Western blotting and co-immunoprecipitation were used to study protein interactions and phosphorylation states.
• Inhibition of p38 mitogen-activated protein kinase (MAPK) was employed to block signaling pathways.
• Nuclear factor AP-1 activation was evaluated through c-fos and c-jun phosphorylation and AP-1 dimer levels.

Main Results:

• Laminin (Ln) modulates vascular endothelial growth factor (VEGF) activity through poly ADP-ribosylation (PAR).
• Ln influences NAD(+) levels and lactate dehydrogenase (LDH) isoenzyme expression.
• The alpha(6)beta(4) integrin-FAK-src-p38 MAPK pathway mediates laminin's effect on LDH-B gene expression.
• Laminin stimulation leads to increased phosphorylation of p38 MAPK, c-fos, and c-jun.
• Activation of the transcription factor AP-1 was observed in cells cultured on laminin.

Conclusions:

• Laminin modulates endothelial cell function relevant to angiogenesis.
• The alpha(6)beta(4) integrin signaling pathway is critical for laminin's effects.
• Laminin influences angiogenesis by regulating VEGF activity and downstream signaling cascades, including p38 MAPK and AP-1 activation.