Vps33b regulates Vwf-positive vesicular trafficking in megakaryocytes.
Mutations of vacuolar protein sorting-associated protein 33b (VPS33B) cause arthrogryposis, renal dysfunction, and cholestasis syndrome, and a lack of platelet α-granules in the affected patients. Conditional Vps33b knockout mice were developed to investigate the function(s) of Vps33b in platelet α-granule formation. We found that early embryonic deletion of Vps33b was lethal. PF4-Cre-driven megakaryocyte-targeted Vps33b gene deletion greatly diminished Vps33b expression in platelets, but had no effect on platelet α-granule formation and protein content. Tamoxifen-induced, haematopoietic stem cell (HSC)-specific Vps33b deletion completely depleted Vps33b in platelets, caused the absence of α-granules, and increased the number of vacuoles in platelets and megakaryocytes. VPS33B association with VIPAS39, α-tubulin, and SEC22B was identified by co-immunoprecipitation, mass spectra, and immunoblotting in human embryonic kidney 293T (HEK293T) cells. Also, pull-down experiments revealed that VIPAS39 bound to intact VPS33B; in contrast, α-tubulin and SEC22B separately interacted with the sec1-like domains of VPS33B. Vps33b deficiency in megakaryocytes disturbs the redistribution of Vipas39 and Sec22b to proplatelets, and interrupted the co-localization of Sec22b with Vwf-positive vesicles. The data presented in this study suggest that Vps33b is involved in α-granule formation possibly by facilitating the Vwf-positive vesicular trafficking to α-granule-related vacuoles in megakaryocytes. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Department of Biochemistry and Molecular Cell Biology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.|Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Jing
J
Dai
Department of Biochemistry and Molecular Cell Biology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.|Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Yeling
Y
Lu
Department of Biochemistry and Molecular Cell Biology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Conghui
C
Wang
Department of Biochemistry and Molecular Cell Biology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Xue
X
Chen
Department of Biochemistry and Molecular Cell Biology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Xuemei
X
Fan
Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Hao
H
Gu
Department of Biochemistry and Molecular Cell Biology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Xiaolin
X
Wu
Department of Biochemistry and Molecular Cell Biology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Kemin
K
Wang
Department of Biological Sciences, University of Memphis, Memphis, TN, USA.
T Kent
TK
Gartner
Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Junke
J
Zheng
Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Guoqiang
G
Chen
Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Xuefeng
X
Wang
Department of Biochemistry and Molecular Cell Biology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Junling
J
Liu
D000818:Animals; D001792:Blood Platelets / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008533:Megakaryocytes / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D021381:Protein Transport / Q000235:genetics*; D022142:Secretory Vesicles / Q000378:metabolism*; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*; D014841:von Willebrand Factor / Q000378:metabolism*
C000601834:VPS33B protein, mouse; D033921:Vesicular Transport Proteins; D014841:von Willebrand Factor
VPS33B complex; megakaryocyte; platelet; vesicle trafficking; α-granules