The Cytoplasmic Domain of the Hyaluronan Receptor for Endocytosis (HARE) Contains Multiple Endocytic Motifs Targeting Coated Pit-mediated Internalization

Regulation of Hyaluronan (HA) Metabolism Mediated by HYBID (Hyaluronan-binding Protein Involved in HA Depolymerization, KIAA1199) and HA Synthases in Growth Factor-stimulated Fibroblasts

“…Human synovial fibroblasts from a normal subject (60-year-old male), a patient with OA (61-year-old male), and a patient with RA (51-year-old male) were purchased from Toyobo. Synovial fibroblasts were maintained in Dulbecco's modified Eagle's medium (Sigma) supplemented with 10% (v/v) FBS, 100 units/ml penicillin, and 100 g/ml streptomycin at 37°C in a humidified atmosphere containing 5% CO 2 .…”

“…The turnover of HA in most tissues is extraordinarily rapid; the half-life of HA in the skin, which contains about half of all HA in the body, is 1-1.5 days (2). Thus, the tight control of HA synthesis and degradation is necessary for this turnover and seems to finely balance the amounts of high molecular mass HA (1,000 -10,000 kDa) within tissues (1,2). On the other hand, an imbalance of synthesis and degradation causes the accumulation of HA with different molecular weights, which is commonly observed in diseases such as arthritis and cancers (3)(4)(5).…”

“…HA is ubiquitously present as a major component in vertebrate connective tissues such as skin and synovial membrane and contributes to space filling, lubrication, and cell proliferation and migration (1). The turnover of HA in most tissues is extraordinarily rapid; the half-life of HA in the skin, which contains about half of all HA in the body, is 1-1.5 days (2). Thus, the tight control of HA synthesis and degradation is necessary for this turnover and seems to finely balance the amounts of high molecular mass HA (1,000 -10,000 kDa) within tissues (1,2).…”

Hyaluronan Endocytosis: Mechanisms of Uptake and Biological Functions

“…Deletion analyses of the signaling domains showed that three signal sequences (YSYFRI, FQHF, and NPLY) provide redundancy to mediate coated pit targeting and endocytosis of HARE. Importantly, the coated pit targeting domains did not impact binding of the HARE ectodomain to HA showing that HA binding to HARE and HARE mediated endocytosis of HA are separate events [39].…”

Functional Aspects of the Hyaluronan and Chondroitin Sulfate Receptors

“…The cytoplasmic domain contains three motifs involved in clathrin/AP-2 targeting or intracellular trafficking after endocytosis (e.g., YSYFRI, FQHF, and NPLY) [174]. Subcellular localization of recombinant rat HARE is primarily at the cell surface and in endocytic vesicles, but not lysosomes, suggesting that HARE is recycled back to the cell surface [151].…”