Hepatocyte growth factor-mediated renal epithelial branching morphogenesis is regulated by glypican-4 expression

The glypican (Gpc) family of cell surface heparan sulfate proteoglycans are expressed in a tissue-specific and developmentally regulated fashion. To determine if individual Gpcs can modulate heparin-binding growth factor signaling, we examined hepatocyte growth factor (HGF)-stimulated mitogenic, motogenic, and morphogenic responses of renal tubular cells expressing different Gpcs. Adult inner medullary collecting duct (IMCD) cells were found to express primarily Gpc4 and to proliferate, migrate, and form tubules with HGF, correlating with sustained extracellular signal-regulated kinase (ERK) activation. Embryonic IMCD cells expressing predominantly Gpc3 proliferated and migrated in response to HGF but activated ERK only transiently and failed to form tubules. Overexpressing Gpc-4 but not Gpc-3 or Gpc-1 led to sustained HGF-stimulated ERK activation and rescued the tubulogenic response in these cells. These results demonstrate that both signaling and phenotypic responses to HGF can be regulated by specific Gpc expression patterns.