c-Jun N-terminal kinases (JNKs) are among the most crucial mitogen-activated protein kinases (MAPKs) and regulate various cellular processes, including cell proliferation, apoptosis, autophagy, and inflammation. Microbes heavily rely on cellular signaling pathways for their effective replication; hence, JNKs may play important roles in infectious diseases. In this review, we describe the basic signaling properties of MAPKs and JNKs in apoptosis, autophagy, and inflammasome activation. Furthermore, we discuss the roles of JNKs in various infectious diseases induced by viruses, bacteria, fungi, and parasites, as well as their potential to serve as targets for the development of therapeutic agents for infectious diseases. We expect this review to expand our understanding of the JNK signaling pathway’s role in infectious diseases and provide important clues for the prevention and treatment of infectious diseases.
Chicken cathelicidin-2 (CATH-2) as a host defense peptide has been identified to have potent antimicrobial and immunomodulatory activities. Here, we reported the mechanism by which CATH-2 modulates NLRP3 inflammasome activation. Our results show that CATH-2 and ATP as a positive control induced secretion of IL-1β and IL-1α in LPS-primed macrophages but did not affect secretion of IL-6, IL-12 and TNF-α. Furthermore, CATH-2 induced caspase-1 activation and oligomerization of apoptosis-associated speck-like protein containing a carboxy- terminal caspase recruitment domain (ASC), which is essential for NLRP3 inflammasome activation. However, CATH-2 failed to induce IL-1β secretion in Nlrp3−/−, Asc−/− and Casp1−/− macrophages. Notably, IL-1β and NLRP3 mRNA expression were not affected by CATH-2. In addition, CATH-2-induced NLRP3 inflammasome activation was mediated by K+ efflux but independent of the P2X7 receptor that is required for ATP-mediated K+ efflux. Gene interference of NEK7 kinase which has been identified to directly interact with NLRP3, significantly reduced IL-1β secretion and caspase-1 activation induced by CATH-2. Furthermore, confocal microscopy shows that CATH-2 significantly induced lysosomal leakage with the diffusion of dextran fluorescent signal. Cathepsin B inhibitors completely abrogated IL-1β secretion and caspase-1 activation as well as attenuating the formation of ASC specks induced by CATH-2. These results all indicate that CATH-2-induced activation of NLRP3 inflammasome is mediated by K+ efflux, and involves the NEK7 protein and cathepsin B. In conclusion, our study shows that CATH-2 acts as a second signal to activate NLRP3 inflammasome. Our study provides new insight into CATH-2 modulating immune response.
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