title: Hax1 regulates neutrophil adhesion and motility through RhoA.
abstract: Kostmann disease is an inherited severe congenital neutropenia syndrome associated with loss-of-function mutations in an adaptor protein HS1-associated protein X-1 (Hax1). How Hax1 regulates neutrophil function remains largely unknown. In this paper, we use ribonucleic acid interference to deplete Hax1 in the neutrophil-like cell line PLB-985 and identify Hax1 as a negative regulator of integrin-mediated adhesion and chemotaxis. Using microfluidics, we show that depletion of Hax1 impairs neutrophil uropod detachment and directed migration. Hax1-deficient cells also display increased integrin-mediated adhesion and reduced RhoA activity. Moreover, depletion of RhoA induces increased neutrophil adhesion and impaired migration, suggesting that Hax1 regulates neutrophil adhesion and chemotaxis through RhoA. Accordingly, activation of RhoA is sufficient to rescue adhesion of Hax1-deficient neutrophils. Together, our findings identify Hax1 as a novel regulator of neutrophil uropod detachment and chemotaxis through RhoA.
authors.affiliation: Department of Pediatrics, University of Wisconsin-Madison, Madison, WI 53706, USA.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Cavnar
authors.forename: Erwin
authors.initials: E
authors.lastname: Berthier
authors.forename: David J
authors.initials: DJ
authors.lastname: Beebe
authors.forename: Anna
authors.initials: A
authors.lastname: Huttenlocher
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D017209:Apoptosis; D001665:Binding Sites; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D002465:Cell Movement; D002633:Chemotaxis; D005786:Gene Expression Regulation; D018922:HL-60 Cells; D006801:Humans; D044085:Microfluidics; D009154:Mutation; D009504:Neutrophils / Q000166:cytology; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C104759:HAX1 protein, human; C066737:RHOA protein, human; D020742:rhoA GTP-Binding Protein