HECTD1 controls the protein level of IQGAP1 to regulate the dynamics of adhesive structures

Abstract

BackgroundCell migration including collective cell movement and individual cell migration are crucial factors in embryogenesis. During the spreading/migration of cells, several types of adhesive structures physically interacting with the extracellular matrix (ECM) or with another cell have been described and the formation and maturation of adhesion structures are coordinated, however the molecular pathways involved are still not fully understood.ResultsWe generated a mouse embryonic fibroblast line (MEF) from homozygous mutant (Hectd1 R/R, Hectd1 Gt(RRC200)) mouse of the E3 ubiquitin ligase for inhibin B receptor (Hectd1). Detailed examination of cell motion on MEF cells demonstrated that loss of Hectd1 resulted in accelerated cell spreading and migration but impaired directionality of migration. In Hectd1 R/R cells paxillin and zyxin were largely mis-localized, whereas their expression levels were unchanged. In addition the formation of focal adhesions (FAs) was impaired and the focal complexes (FXs) were increased. We further identified HECTD1 as a key regulator of IQGAP1. IQGAP1 co-localized together with HECTD1 in the leading edge of cells. HECTD1 interacted with IQGAP1 and regulated its degradation through ubiquitination. Over-expression of IQGAP1 in control MEF phenocopied the spreading and migration defects of Hectd1 R/R cells. In contrast, siRNA-mediated knockdown of IQGAP1 rescued the defects in cellular movement of Hectd1 R/R cells.ConclusionsThe E3 ligase activity of Hectd1 regulates the protein level of IQGAP1 through ubiquitination and therefore mediates the dynamics of FXs including the recruitment of paxillin and actinin. IQGAP1 is one of the effectors of HECTD1.Electronic supplementary materialThe online version of this article (doi:10.1186/s12964-016-0156-8) contains supplementary material, which is available to authorized users.

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“…Wound healing assay. The wound healing assay for HeLa cells was performed as previously described (12). Three independent experimental repeats were performed.…”

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The serine/threonine protein kinase ofStreptococcus suisserotype 2 affects the ability of the pathogen to penetrate the blood-brain barrier

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