Pivotal function for cytoplasmic protein FROUNT in CCR2-mediated monocyte chemotaxis

Abstract

Ligation of the chemokine receptor CCR2 on monocytes and macrophages with its ligand CCL2 results in activation of the cascade consisting of phosphatidylinositol-3-OH kinase (PI(3)K), the small G protein Rac and lamellipodium protrusion. We show here that a unique clathrin heavy-chain repeat homology protein, FROUNT, directly bound activated CCR2 and formed clusters at the cell front during chemotaxis. Overexpression of FROUNT amplified the chemokine-elicited PI(3)K-Rac-lamellipodium protrusion cascade and subsequent chemotaxis. Blocking FROUNT function by using a truncated mutant or antisense strategy substantially diminished signaling via CCR2. In a mouse peritonitis model, suppression of endogenous FROUNT markedly prevented macrophage infiltration. Thus, FROUNT links activated CCR2 to the PI(3)K-Rac-lamellipodium protrusion cascade and could be a therapeutic target in chronic inflammatory immune diseases associated with macrophage infiltration.

Role of CC Chemokine Receptor 2 in Bone Marrow Cells in the Recruitment of Macrophages into Obese Adipose Tissue

“…In this study, we confirmed that CCR2-Jurkat migrate dose-dependently toward recombinant mouse MCP-1; 100 nM was most effective to induce chemotaxis ( Fig. S2), which is consistent with a previous report (25). Thus, 100 nM recombinant MCP-1 was used for further analysis.…”

Accelerated protein evolution analysis reveals genes and pathways associated with the evolution of mammalian longevity

“…Candidate proteins from the high stringency threshold include HERC4, a probable E3 ubiquitin-protein ligase by sequence similarity (Wu et al 2006), and NUP85, a component of the nuclear pore complex thought to play a role in phosphatidyl-inositol-3-kinase-dependent pathways (Terashima et al 2005). CAPNS1, scoring 4.0 (rank 7; moderate), belongs to a well-conserved family of calcium-dependent, cysteine proteases whose link to cellular senescence and DNA damage response has been studied (Demarchi and Schneider 2007).…”

An improved Akt reporter reveals intra- and inter-cellular heterogeneity and oscillations in signal transduction

“…The extent of Akt membrane recruitment in these studies was highly variable. Furthermore, none of these studies appear to have compared the activity and/or function of these constructs to the endogenous protein (Asano et al, 2008;Calleja et al, 2003;Carpten et al, 2007;Cenni et al, 2003;Currie et al, 1999;Du et al, 2014;Feng et al, 2014;Gonzalez and McGraw, 2009;Huang et al, 2011;Imazaki et al, 2010;Kontos et al, 1998;Lasserre et al, 2008;Parikh et al, 2012;Rodríguez-Escudero et al, 2005;Servant et al, 2000;Terashima et al, 2005;Watton and Downward, 1999;Zhang et al, 2009). While GFP remains the most commonly used fluorescent protein, there are a growing number of publications that report fusion protein dysfunction (Goto et al, 2003;Huang and Shusta, 2006;Kalatskaya et al, 2006;Liu et al, 1999;Yantsevich et al, 2009) and mislocalisation (Skube et al, 2010;Zhu et al, 2013), which one group has attributed to the affinity of eGFP for the nucleus (Seibel et al, 2007).…”