Golgin knockouts alter extracellular matrix secretion

The secretion of extracellular matrix (ECM) proteins is vital to the maintenance of tissue health. One 28 major control point of this process is the Golgi apparatus, whose dysfunction causes numerous 29 connective tissue disorders. Golgi function is tightly linked to its structure, which is maintained by the 30 cytoskeleton and Golgi organising proteins. We sought to investigate the role of two of these 31 organising proteins, the golgins GMAP210 and Golgin-160, in ECM secretion. We found that loss of 32 either protein had distinct impacts on Golgi organisation. GMAP210 loss caused cisternal 33 fragmentation and dilation, alongside the accumulation of tubulovesicular structures. Meanwhile, 34 Golgin-160 knockout lead to Golgi fragmentation and vesicle build-up. Nonetheless, loss of each 35 protein had a similar impact on ECM secretion and glycosaminoglycan synthesis. We therefore 36 propose that golgins are collectively required to create the correct physical-chemical space to 37 support efficient ECM protein secretion and modification. This is the first time that Golgin-160 has 38 been shown to be required for ECM secretion.