We have two projects. 1. What is the signal transduction pathway link chemokine GPCR signaling to the reorganization of actin cytoskeleton during neutrophil chemotaxis? Chemotaxis requires precisely coordinated polymerization and depolymerization of the actin cytoskeleton at leading fronts of migrating cells. However, GPCR activation-controlled F-actin depolymerization remains largely elusive. Recently, we identify slingshot 2 (SSH2), a phosphatase of cofilin (actin depolymerization factor), as a target of PKD1 that regulates cofilin phosphorylation and remodeling of the actin cytoskeleton during neutrophil chemotaxis (Xu et al. MBoC, 2015) 2. What is the role of beta-arrestin in chemokine GPCR-mediated neutrophil chemotaxis? β-arrestins have emerged as key regulators of cytoskeletal re-arrangement that are required for directed cell migration. While it is known that β-arrestins are required for formyl-Met-Leu-Phe receptor (FPR) recycling, less is known about their role in regulating FPR mediated neutrophil chemotaxis. Here, we show that β-arrestin1 (ArrB1) co-localized with F-actin in the leading edge of neutrophil-like HL-60 cells during chemotaxis and its knockdown resulted in markedly reduced migration within fMLP gradients. The small GTPase Rap2 was found to bind ArrB1 under resting conditions but dissociated upon fMLP stimulation. The FPR-dependent activation of Rap2 required ArrB1 but was independent of Gi activity. Significantly, depletion of either ArrB1 or Rap2 resulted in reduced chemotaxis and defects in cellular re-polarization within fMLP gradients. These data strongly suggest a model in which FPR is able to direct ArrB1 and other bound proteins that are required for lamillopodial extension to the leading edge in migrating neutrophils, thereby orientating and directing cell migration (Gera et al, to be submitted).

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5
Fiscal Year
2015
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Gera, Nidhi; Swanson, Kenneth D; Jin, Tian (2017) ?-Arrestin 1-dependent regulation of Rap2 is required for fMLP-stimulated chemotaxis in neutrophil-like HL-60 cells. J Leukoc Biol 101:239-251
Wang, Gang; Cao, Luyang; Liu, Xiaowen et al. (2016) Oxidant Sensing by TRPM2 Inhibits Neutrophil Migration and Mitigates Inflammation. Dev Cell 38:453-62
Xu, Xuehua; Yun, Michelle; Wen, Xi et al. (2016) Quantitative Monitoring Spatiotemporal Activation of Ras and PKD1 Using Confocal Fluorescent Microscopy. Methods Mol Biol 1407:307-23
Wang, Youhong; Xu, Xuehua; Pan, Miao et al. (2016) ELMO1 Directly Interacts with G?? Subunit to Transduce GPCR Signaling to Rac1 Activation in Chemotaxis. J Cancer 7:973-83
Xu, Xuehua; Gera, Nidhi; Li, Hongyan et al. (2015) GPCR-mediated PLC??/PKC?/PKD signaling pathway regulates the cofilin phosphatase slingshot 2 in neutrophil chemotaxis. Mol Biol Cell 26:874-86
Li, Hongyan; Yang, Lei; Fu, Hui et al. (2013) Association between Gýýi2 and ELMO1/Dock180 connects chemokine signalling with Rac activation and metastasis. Nat Commun 4:1706
Guo, Jia; Xu, Xuehua; Rasheed, Taban K et al. (2013) Genistein interferes with SDF-1- and HIV-mediated actin dynamics and inhibits HIV infection of resting CD4 T cells. Retrovirology 10:62
Guo, Jia; Xu, Xuehua; Yuan, Wen et al. (2012) HIV gp120 is an aberrant chemoattractant for blood resting CD4 T cells. Curr HIV Res 10:636-42
Chen, Yan; Yue, Shen; Xie, Lu et al. (2011) Dual Phosphorylation of suppressor of fused (Sufu) by PKA and GSK3beta regulates its stability and localization in the primary cilium. J Biol Chem 286:13502-11
Kim, Jung-Sik; Xu, Xuehua; Li, Huifang et al. (2011) Mechanistic analysis of a DNA damage-induced, PTEN-dependent size checkpoint in human cells. Mol Cell Biol 31:2756-71