Laminin-triggered integrin signaling potentiates γ-enolase-induced neurite outgrowth

Neurite growth is regulated by trophic support and the extracellular matrix (ECM). γ-Enolase, a neuron-specific enolase isoform, promotes neurite outgrowth through neurotrophic-like activity, but the contribution of ECM engagement and integrin signaling remains unclear. Here, we examined the role of laminin, collagen, and poly-L-lysine in γ-enolase peptide-induced neuritogenesis in neuroblastoma SH-SY5Y and pheochromocytoma PC12 cells. Treatment with a synthetic C-terminal γ-enolase peptide (γ-Eno) rapidly induced neurite outgrowth and actin remodeling, with laminin providing the strongest enhancement, particularly in SH-SY5Y cells. γ-Eno increased surface expression of β1 integrin and, to a lesser extent, α1 integrin, alongside a stronger neurite response on laminin. In laminin-coated cells, actin remodeling was evident within 3 h, followed by increased neurite formation at 24 h and significant neurite elongation at 48 h. Mechanistically, γ-Eno induced focal adhesion kinase (FAK) phosphorylation, which was significantly increased in both cell types on laminin and collagen. Extracellular signal-regulated kinases 1 and 2 (ERK1/2) activation was cell type- and ECM-dependent, whereas Akt phosphorylation increased significantly in SH-SY5Y cells but did not change markedly in PC12 cells. Integrin blockade with GRGDS attenuated γ-Eno-induced neurite outgrowth, MAP2 expression, and FAK phosphorylation. GRGDS also reduced Akt phosphorylation in SH-SY5Y cells and attenuated ERK1/2 phosphorylation in PC12 cells, supporting cell type-specific downstream signaling. These findings show that laminin-mediated integrin signaling enhances γ-enolase-induced neurite outgrowth and is associated with integrin-dependent FAK activation, with ERK1/2 and Akt contributing in a context-dependent manner.