Investigating the Role of Matrix Metalloproteinases in Cytoneme-mediated Inter-organ Fgf Dispersion in Drosophila

Abstract

Precise intercellular communication mediated by secreted signaling proteins is essential for the development and homeostasis of multicellular organisms. Recent studies have shown that cells regulate signal dispersion through thin, actin-based filopodia-like protrusions called cytonemes, which transport signaling molecules across tissues and deliver them directly to specific target cells. To investigate the mechanism of contact-mediated signal release at cytoneme contact sites, we examined fibroblast growth factor (FGF) signaling in Drosophila. Specifically, we tested whether matrix metalloproteinases (MMPs), known cell-surface sheddases, are required for the release of GPI-anchored FGF at cytoneme contact sites to facilitate uptake by receiving cells. Using an ex vivo culture assay of developing Drosophila wing imaginal discs, we performed quantitative microscopy to analyze the levels of transfer of fluorescently tagged FGF from FGF-producing cells to FGF-receiving cells over time. Inhibition of MMP activity using GM6001, a broad-range MMP inhibitor, significantly reduced FGF exchange levels between cells within the developing tissue compared with control cultures. These findings demonstrate that MMP activity is required for efficient FGF exchange and provide direct support for previous observations that MMP2 mediates the shedding of GPI-anchored FGF at cytoneme contact sites, thereby promoting signal transfer between cells via cytoneme contacts.