Cell-matrix adhesion regulates membrane trafficking controlling anchorage-dependent signaling. While a dynamic Golgi complex can contribute to this pathway, its regulation by adhesion remains unclear. Here we report that loss of adhesion dramatically disorganized the Golgi in mouse and human fibroblast cells. Golgi integrity is restored rapidly upon integrin-mediated re-adhesion to FN and is disrupted by integrin blocking antibody. In suspended cells, the cis, cis-medial and trans-Golgi networks differentially disorganize along the microtubule network but show no overlap with the ER, making this disorganization distinct from known Golgi fragmentation. This pathway is regulated by an adhesion-dependent reduction and recovery of Arf1 activation. Constitutively active Arf1 disrupts this regulation and prevents Golgi disorganization due to loss of adhesion. Adhesion-dependent Arf1 activation regulates its binding to the microtubule minus-end motor protein dynein to control Golgi reorganization, which is blocked by ciliobrevin. Adhesion-dependent Golgi organization controls its function, regulating cell surface glycosylation due to loss of adhesion, which is blocked by constitutively active Arf1. This study, hence, identified integrin-dependent cell-matrix adhesion to be a novel regulator of Arf1 activation, controlling Golgi organization and function in anchorage-dependent cells.

Cell-matrix adhesion regulates membrane trafficking to control anchorage-dependent signaling. While a dynamic Golgi complex can contribute to this pathway, its control by adhesion remains untested. We find the loss of adhesion rapidly disorganizes the Golgi in mouse and human fibroblast cells, its integrity restored rapidly on re-adhesion to fibronectin (but not poly-l-lysine coated beads) along the microtubule network. Adhesion regulates the trans-Golgi more prominently than the cis /cis-medial Golgi, though they show no fallback into the ER making this reorganization distinct from known Golgi fragmentation. This is controlled by an adhesion-dependent drop and recovery of Arf1 activation, mediated through the Arf1 GEF BIG1/2 over GBF1. Constitutively active Arf1 disrupts this regulation and prevents Golgi disorganization in non-adherent cells. Adhesion regulates active Arf1 binding to the microtubule minus-end motor protein dynein to control Golgi reorganization, which ciliobrevin blocks. This regulation by adhesion controls Golgi function, promoting cell surface glycosylation on the loss of adhesion that constitutively active Arf1 blocks. This study hence identifies cell-matrix adhesion to be a novel regulator of Arf1 activation, controlling Golgi organization and function in anchorage-dependent cells.Summary StatementThis study identifies a role for cell-matrix adhesion in regulating organelle (Golgi) architecture and function which could have implications for multiple cellular pathways and function.