Study on the regulatory role of MINK1 gene in the activation of NLRP3 inflammasome in common carp (Cyprinus carpio L.)

The nucleotide oligomerization domain (NOD)-like receptor protein 3 (NLRP3) inflammasome is a cytosolic multiprotein complex that can be activated by a wide variety of stimuli. However, dysregulated activation of NLRP3 is implicated in the pathogenesis of chronic inflammatory diseases. Hence, the activity of NLRP3 is intricately governed by several regulatory mechanisms. Misshapen-like kinase 1 (MINK1), a serine/threonine kinase, plays an important role in the immune cell differentiation and inflammatory response regulation in mammals; however, its regulatory function in NLRP3 inflammasome activation in fish remains poorly understood. In the present study, a homolog gene of MINK1 (<i>Cc</i>MINK1) was cloned and functionally characterized in common carp (<i>Cyprinus carpio</i> L.). The expression profiling disclosed that <i>CcMINK1</i> was upregulated under spring viremia of carp virus (SVCV) and <i>Aeromonas hydrophila</i> stimulation. Overexpression of <i>Cc</i>MINK1 promoted <i>Cc</i>NLRP3-mediated inflammasome activation, including apoptosis-associated speck-like protein containing a CARD (ASC) oligomerization, speck formation, cysteine-requiring aspartate protease A/B (Caspase-A/B) enzyme activity and interleukin-1β (IL-1β) cleavage. Mechanistically, <i>Cc</i>MINK1 interacted with <i>Cc</i>NLRP3 via its S_TKC domain and facilitated <i>Cc</i>NLRP3 phosphorylation, thereby promoting its aggregation and activation. Collectively, these discoveries unveil a novel regulatory mechanism that governs the functional regulation of <i>Cc</i>NLRP3 and fine-tuning innate immune responses in teleost.