Rab8 attenuates Wnt signaling and is required for mesenchymal differentiation into adipocytes

Ewa Stypulkowski, Qiang Feng, Ivor Joseph, Victoria Farrell, Juan Flores, Shiyan Yu, Ryotaro Sakamori, Jiaxin Sun, Sheila Bandyopadhyay, Soumyashree Das, Radek Dobrowolski, Edward M. Bonder, Miao Hsueh Chen, Nan Gao

Research output: Contribution to journalArticlepeer-review

Abstract

Differentiation of mesenchymal stem cells into adipocyte requires coordination of external stimuli and depends upon the functionality of the primary cilium. The Rab8 small GTPases are regulators of intracellular transport of membrane-bound structural and signaling cargo. However, the physiological contribution of the intrinsic trafficking network controlled by Rab8 to mesenchymal tissue differentiation has not been fully defined in vivo and in primary tissue cultures. Here, we show that mouse embryonic fibroblasts (MEFs) lacking Rab8 have severely impaired adipocyte differentiation in vivo and ex vivo. Immunofluorescent localization and biochemical analyses of Rab8a-deficient, Rab8b-deficient, and Rab8a and Rab8b double-deficient MEFs revealed that Rab8 controls the Lrp6 vesicular compartment, clearance of basal signalosome, traffic of frizzled two receptor, and thereby a proper attenuation of Wnt signaling in differentiating MEFs. Upon induction of adipogenesis program, Rab8a- and Rab8b-deficient MEFs exhibited severely defective lipid-droplet formation and abnormal cilia morphology, despite overall intact cilia growth and ciliary cargo transport. Our results suggest that intracellular Rab8 traffic regulates induction of adipogenesis via proper positioning of Wnt receptors for signaling control in mesenchymal cells.

Original languageEnglish (US)
Article number100488
JournalJournal of Biological Chemistry
Volume296
DOIs
StatePublished - Jan 1 2021

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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