Platelet-derived growth factor alpha and beta receptors have overlapping functional activities towards fibroblasts.

Background: Platelet-derived growth factor (PDGF) signalling is essential for many key cellular processes in mesenchymal cells. As there is redundancy in signalling between the five PDGF ligand isoforms and three PDGF receptor isoforms, and deletion of either of the receptors in vivo produces an embryonic lethal phenotype, it is not know which ligand and receptor combinations mediate specific cellular functions. Fibroblasts are key mediators in wound healing and tissues repair.

Platelet-derived growth factor signaling in mesenchymal cells.

Platelet-derived growth factors (PDGFs) and their receptors are major mitogens for many cell types of mensenchymal origin, including fibroblasts and vascular smooth muscle cells (VSMCs). Their role in enhancing migratory and proliferative responses and extracellular matrix synthesis in these cells, make them key regulators of critical biological functions and in tissue diseases including tissue remodeling, scarring and fibrosis. The activities of the PDGFs have been extensively characterized at the molecular and cellular level and in in vivo model systems.

UBAP1 is a component of an endosome-specific ESCRT-I complex that is essential for MVB sorting.

Endosomal sorting complexes required for transport (ESCRTs) regulate several events involving membrane invagination, including multivesicular body (MVB) biogenesis, viral budding, and cytokinesis. In each case, upstream ESCRTs combine with additional factors, such as Bro1 proteins, to recruit ESCRT-III and the ATPase VPS4 in order to drive membrane scission. A clue to understanding how such diverse cellular processes might be controlled independently of each other has been the identification of ESCRT isoforms.