Mechanical strain stimulates COPII-dependent trafficking via Rac1.
                            
                                blue
                            
                            
                                CRY2/CIB1
                            
                            
                                
                                    HeLa
                                
                            
                            
                                Control of cytoskeleton / cell motility / cell shape
                            
                                Control of intracellular / vesicular transport
                            
                            
                            
                            
                            
                        
                        
                        
                        
                            Abstract:
                            Secretory trafficking from the endoplasmic reticulum (ER) is subject to regulation by extrinsic and intrinsic factors. While much of the focus has been on biochemical triggers, little is known whether and how the ER is subject to regulation by mechanical signals. Here, we show that COPII-dependent ER-export is regulated by mechanical strain. Mechanotransduction to the ER was mediated via a previously unappreciated ER-localized pool of the small GTPase Rac1. Mechanistically, we show that Rac1 interacts with the small GTPase Sar1 to drive budding of COPII carriers and stimulate ER-to-Golgi transport. Altogether, we establish an unprecedented link between mechanical strain and export from the ER.