ABRO1 Regulates Neutrophil Chemotaxis By Promoting The Deubiquitination Of β-Arrestin 2

Abraxas brother 1(ABRO1)is used as a platform to assemble with BRCC3,BRE and MERIT40 to form a deubiquitinating enzyme BRISC complex.ABRO1 is an essential component of the BRISC complex,and ABRO1 deficiency leads to a complete loss of the activity of the BRISC complex.BRISC is a multifunctional protein complex that participates in the regulation of various biological processes such as interferon signaling,NLRP3 activation,and DNA replication by deubiquitinating specific substrates.By using ABRO1 globle and neutrophil-specific knockout mice our laboratory previously found that the absence of ABRO1 improves neutrophil chemotaxis and promotes neutrophils aggregation in the infected areas,thereby promoting bacterial clearance and resisting sepsis induced by cecal ligation and puncture(CLP).Further studies demonstrated that knockout of ABRO1 selectively promotes CXCR2 receptor-mediated neutrophil chemotaxis,but its molecular mechanism is not clear.This paper found that ABRO1 interacts with β-Arrestin 2,a key protein of the CXCR2 receptor downstream pathway.In neutrophils,stimulation with CXCL1 promotes the interaction of β-Arrestin 2 with ABRO1.Deficiency of ABRO1 potently increases the K63-linked ubiquitinaiton of β-Arrestin 2 induced by CXCL1,enhances the interaction of β-Arrestin 2 with Cofilin and CIN,and promotes the dephosphorylation and activation of Cofilin,thereby enhancing the assembly of F-actin.In HEK-293 T cells,the K63-linked ubiquitination promotes the interaction between β-Arrestin 2 and Cofilin.Point mutation experiments showed that the lysine at amino acid position 139(K139)of β-Arrestin 2 protein was the key amino acid for K63-linked ubiquitination of β-Arrestin 2.β-Arrestin 2 K139 R mutation blocks the binding of β-Arrestin 2 to Cofilin and CIN.These results show that BRISC may negatively regulate neutrophil chemotaxis by promoting the K63-linked deubiquitination of β-Arrestin 2and inhibiting Cofilin activation and F-actin assembly.These results show that ABRO1 regulates neutrophil chemotaxis by promoting the deubiquitination of β-Arrestin 2.We identified a new ubiquitination modification site of β-Arrestin 2 and linked its physiological function to neutrophil chemotaxis,which may provide new strategies for the treatment of neutrophil disorder-related diseases.