The T-type voltage-gated Ca2+ channel CaV3.1 involves in the disruption of respiratory epithelial barrier induced by Pasteurella multocida toxin.

Abstract

Pasteurella multocida toxin (PMT) is an exotoxin produced by several members of the zoonotic respiratory pathogen P. multocida. The role of PMT in disrupting the mammalian respiratory barrier remains to be elucidated. In this study, we showed that inoculation of recombinantly expressed PMT increased the permeability of the respiratory epithelial barrier in mouse and respiratory cell models. This was evidenced by a decreased expression of tight junctions (ZO-1, occludin) and adherens junctions (β-catenin, E-cadherin), as well as enhanced cytoskeletal rearrangement. In mechanism, we demonstrated that PMT inoculation induced cytoplasmic Ca²⁺ inflow, leading to an imbalance of cellular Ca²⁺ homoeostasis and endoplasmic reticulum stress. This process further stimulated the RhoA/ROCK signalling, promoting cytoskeletal rearrangement and reducing the expression of tight junctions and adherens junctions. Notably, the T-type voltage-gated Ca²⁺ channel Ca_V3.1 was found to participate in PMT-induced cytoplasmic Ca²⁺ inflow. Knocking out Ca_V3.1 significantly reduced the cytotoxicity induced by PMT on swine respiratory epithelial cells and mitigated cytoplasmic Ca²⁺ inflow stimulated by PMT. These findings suggest Ca_V3.1 contributes to PMT-induced respiratory epithelial barrier disruption.