RhoB links PDGF signaling to cell migration by coordinating activation and localization of Cdc42 and Rac

Lankenau Institute for Medical Research, Wynnewood, Pennsylvania 19096, USA.
Journal of Cellular Biochemistry (Impact Factor: 3.26). 06/2011; 112(6):1572-84. DOI: 10.1002/jcb.23069
Source: PubMed


The small GTPase RhoB regulates endocytic trafficking of receptor tyrosine kinases (RTKs) and the non-receptor kinases Src and Akt. While receptor-mediated endocytosis is critical for signaling processes driving cell migration, mechanisms that coordinate endocytosis with the propagation of migratory signals remain relatively poorly understood. In this study, we show that RhoB is essential for activation and trafficking of the key migratory effectors Cdc42 and Rac in mediating the ability of platelet-derived growth factor (PDGF) to stimulate cell movement. Stimulation of the PDGF receptor-β on primary vascular smooth muscle cells (VSMCs) results in RhoB-dependent trafficking of endosome-bound Cdc42 from the perinuclear region to the cell periphery, where the RhoGEF Vav2 and Rac are also recruited to drive formation of circular dorsal and peripheral ruffles necessary for cell migration. Our findings identify a novel RhoB-dependent endosomal trafficking pathway that integrates RTK endocytosis with Cdc42/Rac localization and cell movement.

Download full-text


Available from: George C Prendergast, Oct 03, 2015
52 Reads
  • Source
    • "While RhoA, Rac and Cdc42 localize to the plasma membrane and are involved in receptor internalization, RhoB is found both at the plasma membrane and endosomes and has been suggested to regulate endosomal traffic [14]. RhoB is involved in traffic to the cell surface, nucleus, or lysosome, and/or activation of a number of signaling molecules, such as RTKs, Akt and Src [15], [16], [17]. It has recently been reported that activated RhoB promotes the polymerization of an actin coat around endosomes and association of these vesicles to subcortical actin cables, thus effectively inhibiting further endosomal transport [18]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Adenovirus type 5 (Ad5) is a non-enveloped DNA virus frequently used as a gene transfer vector. Efficient Ad5 cell entry depends on the availability of its primary receptor, coxsackie and adenovirus receptor, which is responsible for attachment, and integrins, secondary receptors responsible for adenovirus internalization via clathrin-mediated endocytosis. However, efficacious adenovirus-mediated transgene expression also depends on successful trafficking of Ad5 particles to the nucleus of the target cell. It has been shown that changes occurring in tumor cells during development of resistance to anticancer drugs can be beneficial for adenovirus mediated transgene expression. In this study, using an in vitro model consisting of a parental cell line, human laryngeal carcinoma HEp2 cells, and a cisplatin-resistant clone CK2, we investigated the cause of increased Ad5-mediated transgene expression in CK2 as compared to HEp2 cells. We show that the primary cause of increased Ad5-mediated transgene expression in CK2 cells is not modulation of receptors on the cell surface or change in Ad5wt attachment and/or internalization, but is rather the consequence of decreased RhoB expression. We propose that RhoB plays an important role in Ad5 post-internalization events and more particularly in Ad5 intracellular trafficking. To the best of our knowledge, this is the first study showing changed Ad5 trafficking pattern between cells expressing different amount of RhoB, indicating the role of RhoB in Ad5 intracellular trafficking.
    PLoS ONE 01/2014; 9(1):e86698. DOI:10.1371/journal.pone.0086698 · 3.23 Impact Factor
  • Source
    • "RhoB has been shown to play a role in growth factor receptor trafficking and through this mechanism can regulate growth factor receptor signaling under certain circumstances [9,10]. With this in mind, we became interested in determining whether RhoB regulated VEGF-induced angiogenic processes in endothelial cells, in order to identify possible novel targets which might ultimately be useful for enhancing the efficacy of current anti-VEGF/VEGFR blocking strategies. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Recent studies have suggested a role for the small GTPase RhoB in the control of processes required for angiogenesis. However, the mechanisms whereby RhoB exerts control over these processes are not well understood. Given the role of vascular endothelial growth factor (VEGF) in pathological angiogenesis, we were interested in examining whether RhoB contributed to VEGF-induced angiogenic processes. To assess this, RhoB was specifically depleted in human umbilical vein endothelial cells (HUVEC), using siRNA-targeted strategies. The effects of RhoB depletion on VEGF-induced angiogenic activities were assessed using a variety of standard in vitro angiogenesis assays to assess endothelial cell viability, migration and capillary morphogenesis. Effects of RhoB depletion on signaling from other Rho family member proteins was also assessed using specific activity assays for RhoA and RhoC. We observed that although RhoB appeared dispensable for HUVEC viability, RhoB was required for endothelial cell migration, sprouting, and capillary morphogenesis. We also observed that siRNA-mediated depletion of RhoB in HUVEC resulted in increased RhoA activation in response to VEGF stimulation. This increased RhoA activation contributed to the cellular morphogenesis defects observed in RhoB-depleted cells, as inhibition of RhoA activity using C3 transferase, or inhibition of the activity of the downstream RhoA effectors Rho-dependent kinases I and II (ROCK I and II) led to a partial restoration of capillary morphogenesis in the absence of RhoB. Thus our data indicate that RhoB plays a significant role in VEGF-induced endothelial cell morphogenesis in part by negatively regulating the activity of RhoA and the RhoA/ROCK pathway.
    Vascular Cell 02/2012; 4(1):1. DOI:10.1186/2045-824X-4-1
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Figure 1. Regulation of cell migration by signaling endosomes. Leading edge: Cellular polarization, formation of the cell protrusion, lamellipodia and circular ruffles are controlled by the small GTPases Cdc42 and Rac. They are transported toward the plasma membrane on early endosomes in an Arf6-dependent manner. Activation of Cdc42 and Rac involves endosomal association of their GEFs, αPIX and Tiam1, respectively. Src moves on early endosomes toward focal adhesions. PTPD1 localizes to early, late and recycling endosomes upon EGF receptor endocytosis. Late endosomes carrying p14/MP1 MAPK scaffold complex can target focal adhesion and serve as a signaling platform for MAPK pathway (lower panel). Trailing edge: Focal adhesion disassembly requires integrin endocytosis and acto-myosin contractility. Integrins are endocytosed into early endosomes and are further recycled back to the leading edge to form new adhesions. Acto-myosin contractility is locally regulated by Endo180-carrying early endosomes through Rho-ROCK-MLC pathway and potentially through p14/MP1 late endosomes (lower panel).
    Current opinion in cell biology 05/2011; 23(5):615-20. DOI:10.1016/ · 8.47 Impact Factor
Show more