Abstract
Hyaluronan synthases (HAS1-3) are unique in that they are active only when located in the plasma membrane, where they extrude the growing hyaluronan (HA) directly into cell surface and extracellular space. Therefore, traffic of HAS to/from the plasma membrane is crucial for the synthesis of HA. In this study, we have identified Rab10 GTPase as the first protein known to be involved in the control of this traffic. Rab10 colocalized with HAS3 in intracellular vesicular structures and was co-immunoprecipitated with HAS3 from isolated endosomal vesicles. Rab10 silencing increased the plasma membrane residence of HAS3, resulting in a significant increase of HA secretion and an enlarged cell surface HA coat, whereas Rab10 overexpression suppressed HA synthesis. Rab10 silencing blocked the retrograde traffic of HAS3 from the plasma membrane to early endosomes. The cell surface HA coat impaired cell adhesion to type I collagen, as indicated by recovery of adhesion following hyaluronidase treatment. The data indicate a novel function for Rab10 in reducing cell surface HAS3, suppressing HA synthesis, and facilitating cell adhesion to type I collagen. These are processes important in tissue injury, inflammation, and malignant growth.
Highlights
Hyaluronan synthases (HASs) require transport to plasma membrane for the activation of hyaluronan (HA) synthesis
Association of HAS3 with Rab10 in Transport Vesicles—Because nothing was known about the vehicles transporting the HAS proteins between the Golgi complex and plasma membrane, we started by isolating the endosomal vesicles of cells expressing EGFP-HAS3 or HAS3-Myc
We focused on Rab10, one of the significant hits, because it has been shown to be important for the traffic from trans-Golgi to the plasma membrane
Summary
Hyaluronan synthases (HASs) require transport to plasma membrane for the activation of hyaluronan (HA) synthesis. The data indicate a novel function for Rab in reducing cell surface HAS3, suppressing HA synthesis, and facilitating cell adhesion to type I collagen. These are processes important in tissue injury, inflammation, and malignant growth. Several proteins belonging to the vesicular trafficking machinery were identified, including Rab, a member of the Rab family, comprising more than 60 proteins They are master regulators of several aspects of intracellular traffic like transporting cargos from the trans-Golgi network to the PB, 0.1 M sodium phosphate buffer, pH 7.0; PFA, paraformaldehyde; PNS, postnuclear supernatant; MDCK, Madin-Darby canine kidney; EGFP, enhanced green fluorescent protein; PFA, paraformaldehyde; ANOVA, analysis of variance. We show that Rab is a suppressor of HA synthesis and suggest that trafficking of HAS to/from plasma membrane forms a more important regulatory step in HA synthesis than previously anticipated
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
