Neutrophil elastase promotes mucin secretion in airway epithelial cells through the MARCKS/ACK1/cortactin pathway

Excessive mucus secretion in airway epithelial cells is a hallmark of various airway inflammatory diseases. Neutrophil elastase (NE) is a recognized inducer of mucus secretion, yet the precise mechanisms underlying this process remain inadequately understood. This study aims to investigate the roles of myristoylated alanine-rich C-kinase substrate (MARCKS), activated CDC42 kinase 1 (ACK1) and cortactin in airway mucin secretion induced by NE.

Human airway epithelial cells were treated with NE following specific siRNA- mediated knockdown of MARCKS, ACK1 and cortactin. Western blotting and immunofluorescence were used to observe the expression and localization of cortactin, MARCKS and ACK1. The interaction between cortactin and ACK1 was analyzed using co-immunoprecipitation, and MUC5AC protein expression was measured using ELISA.

NE stimulation only increased the phosphorylation levels of MARCKS, ACK1, and cortactin in the cells. Silencing MARCKS inhibited the phosphorylation of ACK1, and silencing ACK1 inhibited the phosphorylation of cortactin. Co-immunoprecipitation showed that ACK1 could directly bind to cortactin. The inhibition of MARCKS and cortactin significantly decreased the production of MUC5AC.

NE induces the phosphorylation of MARCKS, which subsequently facilitates the phosphorylation of ACK1. This cascade enhances the phosphorylation of cortactin, ultimately leading to increased mucus secretion. The MARCKS/ACK1/cortactin pathway is a potential therapeutic target for excessive mucus secretion induced by NE.