Cystic Fibrosis Transmembrane Conductance Regulator Reduces Microtubule-Dependent Campylobacter jejuni Invasion

Abstract

Campylobacter jejuni is a foodborne pathogen that induces gastroenteritis. Invasion and adhesion are essential in the process of C. jejuni infection leading to gastroenteritis. The mucosal layer plays a key role in the system of defense against efficient invasion and adhesion by bacteria, which is modulated by several ion channels and transporters mediated by water flux in the intestine. The cystic fibrosis transmembrane conductance regulator (CFTR) plays the main role in water flux in the intestine, and it is closely associated with bacterial clearance. We previously reported that C. jejuni infection suppresses CFTR channel activity in intestinal epithelial cells; however, the mechanism and importance of this suppression are unclear. This study sought to elucidate the role of CFTR in C. jejuni infection. Using HEK293 cells that stably express wild-type and mutated CFTR, we found that CFTR attenuated C. jejuni invasion and that it was not involved in bacterial adhesion or intracellular survival but was associated with microtubule-dependent intracellular transport. Moreover, we revealed that CFTR attenuated the function of the microtubule motor protein, which caused inhibition of C. jejuni invasion, but did not affect microtubule stability. Meanwhile, the CFTR mutant G551D-CFTR, which had defects in channel activity, suppressed C. jejuni invasion, whereas the ΔF508-CFTR mutant, which had defects in maturation, did not suppress C. jejuni invasion, suggesting that CFTR suppression of C. jejuni invasion is related to CFTR maturation but not channel activity. When these findings are taken together, it may be seen that mature CFTR inhibits C. jejuni invasion by regulating microtubule-mediated pathways. We suggest that CFTR plays a critical role in cellular defenses against C. jejuni invasion and that suppression of CFTR may be an initial step in promoting cell invasion during C. jejuni infection.

Recruitment of LC3 by Campylobacter jejuni to Bacterial Invasion Site on Host Cells via the Rac1-Mediated Signaling Pathway

“…Since the association between autophagy and bacterial invasion signaling is not clearly understood. Recent studies characterized that C. jejuni invasion is associated with cytoskeletal dynamics, such as microtubules ( Hu and Kopecko, 1999 ; Kido et al, 2017 ) or actin filaments ( Biswas et al, 2003 ; Krause-Gruszczynska et al, 2007 ), and intracellular transportation pathway, endocytosis ( Wooldridge et al, 1996 ). We focused on autophagy association in conventional invasion signaling in C. jejuni .…”

“…During C. jejuni infection, actin filament rearrangement, microtubule dynamics, and endocytosis pathway, were involved in the C. jejuni invasion step ( Wooldridge et al, 1996 ; Biswas et al, 2003 ; Krause-Gruszczynska et al, 2007 ; Kido et al, 2017 ). Alternatively, bacterial fibronectin-binding proteins, CadF and FlpA, are regarded as one of the main bacterial adherence factors that activate integrins and trigger host cytoskeletal rearrangement signaling pathway, and facilitate bacterial internalization ( Konkel et al, 1997 ; Talukdar et al, 2020 ).…”