Integrin Acts Upstream of Netrin Signaling to Regulate Formation of the Anchor Cell's Invasive Membrane in C. elegans

Department of Biology, Duke University, Science Drive, Box 90388, Durham, NC 27708, USA.
Developmental Cell (Impact Factor: 9.71). 09/2009; 17(2):187-98. DOI: 10.1016/j.devcel.2009.06.006
Source: PubMed


Integrin expression and activity have been strongly correlated with developmental and pathological processes involving cell invasion through basement membranes. The role of integrins in mediating these invasions, however, remains unclear. Utilizing the genetically and visually accessible model of anchor cell (AC) invasion in C. elegans, we have recently shown that netrin signaling orients a specialized invasive cell membrane domain toward the basement membrane. Here, we demonstrate that the integrin heterodimer INA-1/PAT-3 plays a crucial role in AC invasion, in part by targeting the netrin receptor UNC-40 (DCC) to the AC's plasma membrane. Analyses of the invasive membrane components phosphatidylinositol 4,5-bisphosphate, the Rac GTPase MIG-2, and F-actin further indicate that INA-1/PAT-3 plays a broad role in promoting the plasma membrane association of these molecules. Taken together, these studies reveal a role for integrin in regulating the plasma membrane targeting and netrin-dependent orientation of a specialized invasive membrane domain.

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Available from: Shinji Ihara, Oct 06, 2015
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    • "This same threshold was used in unc-40, unc-6, and madd-2; unc-6 mutants. Quantitative measurements were then made for the volume of fluorescent intensity with these isosurface renderings (Hagedorn et al., 2009). Isosurface renderings for mCherry::MoeABD in madd-2 mutants and wild-type animals shown in Fig. 8 were created with more stringent thresholds set to delineate ectopic and basal F-actin patches in madd-2 animals. "
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    ABSTRACT: The receptor deleted in colorectal cancer (DCC) directs dynamic polarizing activities in animals toward its extracellular ligand netrin. How DCC polarizes toward netrin is poorly understood. By performing live-cell imaging of the DCC orthologue UNC-40 during anchor cell invasion in Caenorhabditis elegans, we have found that UNC-40 clusters, recruits F-actin effectors, and generates F-actin in the absence of UNC-6 (netrin). Time-lapse analyses revealed that UNC-40 clusters assemble, disassemble, and reform at periodic intervals in different regions of the cell membrane. This oscillatory behavior indicates that UNC-40 clusters through a mechanism involving interlinked positive (formation) and negative (disassembly) feedback. We show that endogenous UNC-6 and ectopically provided UNC-6 orient and stabilize UNC-40 clustering. Furthermore, the UNC-40-binding protein MADD-2 (a TRIM family protein) promotes ligand-independent clustering and robust UNC-40 polarization toward UNC-6. Together, our data suggest that UNC-6 (netrin) directs polarized responses by stabilizing UNC-40 clustering. We propose that ligand-independent UNC-40 clustering provides a robust and adaptable mechanism to polarize toward netrin.
    The Journal of Cell Biology 08/2014; 206(5). DOI:10.1083/jcb.201405026 · 9.83 Impact Factor
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    • "Isosurface renderings of mCherry::moeABD were created using Imaris ''isosurface rendering'' function by setting a threshold that outlined the dense F-actin network. Quantitative measurements were made for the volume of fluorescent intensity within these isosurface renderings [19] "
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    ABSTRACT: Cell invasion through basement membrane (BM) occurs in many physiological and pathological contexts. MIG-10, the Caenorhabditiselegans Lamellipodin (Lpd), regulates diverse biological processes. Its function and regulation in cell invasive behavior remain unclear. Using anchor cell (AC) invasion in C. elegans as an in vivo invasion model, we have previously found that mig-10's activity is largely outside of UNC-6 (netrin) signaling, a chemical cue directing AC invasion. We have shown that MIG-10 is a target of the transcription factor FOS-1A and facilitates BM breaching. Combining genetics and imaging analyses, we report that MIG-10 synergizes with UNC-6 to promote AC attachment to the BM, revealing a functional role for MIG-10 in stabilizing AC-BM adhesion. MIG-10 is also required for F-actin accumulation in the absence of UNC-6. Further, we identify mig-10 as a transcriptional target negatively regulated by EGL-43A (C. elegans Evi-1 proto-oncogene), a transcription factor positively controlled by FOS-1A. The revelation of this negative regulation unmasks an incoherent feedforward circuit existing among fos-1, egl-43 and mig-10. Moreover, our study suggests the functional importance of the negative regulation on mig-10 expression by showing that excessive MIG-10 impairs AC invasion. Thus, we provide new insight into MIG-10's function and its complex transcriptional regulation during cell invasive behavior.
    Biochemical and Biophysical Research Communications 08/2014; 452(3). DOI:10.1016/j.bbrc.2014.08.049 · 2.30 Impact Factor
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    • "To determine whether the disruption in invadopodial membrane trafficking was an indirect effect from a general perturbation in vesicle trafficking or polarity, we examined markers of polarity and secretion. Notably, after depletion of unc-60a the integrin receptor INA-1/PAT-3 and the netrin receptor UNC-40 (DCC) were polarized normally to the AC's invasive cell membrane (Fig. 6, A and D; Hagedorn et al., 2009; Ziel et al., 2009). Further, AC deposition of the matrix component hemicentin into the basement membrane (Fig. 6, B and D; Sherwood et al., 2005) and secretion of the EGF-like ligand LIN-3, which induces vulval development, PI(4,5)P 2 , CED-10, and MIG-2 colocalized strongly with LMP-1 at invadopodia and LMP-1 localized to the invadopodium at the site of breach (Fig. 4 D). "
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    ABSTRACT: Invadopodia are protrusive, F-actin-driven membrane structures that are thought to mediate basement membrane transmigration during development and tumor dissemination. An understanding of the mechanisms regulating invadopodia has been hindered by the difficulty of examining these dynamic structures in native environments. Using an RNAi screen and live-cell imaging of anchor cell (AC) invasion in Caenorhabditis elegans, we have identified UNC-60A (ADF/cofilin) as an essential regulator of invadopodia. UNC-60A localizes to AC invadopodia, and its loss resulted in a dramatic slowing of F-actin dynamics and an inability to breach basement membrane. Optical highlighting indicated that UNC-60A disassembles actin filaments at invadopodia. Surprisingly, loss of unc-60a led to the accumulation of invadopodial membrane and associated components within the endolysosomal compartment. Photobleaching experiments revealed that during normal invasion the invadopodial membrane undergoes rapid recycling through the endolysosome. Together, these results identify the invadopodial membrane as a specialized compartment whose recycling to form dynamic, functional invadopodia is dependent on localized F-actin disassembly by ADF/cofilin.
    The Journal of Cell Biology 03/2014; 204(7). DOI:10.1083/jcb.201312098 · 9.83 Impact Factor
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