The VPS33B-binding protein VPS16B is required in megakaryocyte and platelet α-granule biogenesis.
Blood
; 120(25): 5032-40, 2012 Dec 13.
Article
em En
| MEDLINE
| ID: mdl-23002115
ABSTRACT
Patients with platelet α or dense δ-granule defects have bleeding problems. Although several proteins are known to be required for δ-granule development, less is known about α-granule biogenesis. Our previous work showed that the BEACH protein NBEAL2 and the Sec1/Munc18 protein VPS33B are required for α-granule biogenesis. Using a yeast two-hybrid screen, mass spectrometry, coimmunoprecipitation, and bioinformatics studies, we identified VPS16B as a VPS33B-binding protein. Immunoblotting confirmed VPS16B expression in various human tissues and cells including megakaryocytes and platelets, and also in megakaryocytic Dami cells. Characterization of platelets from a patient with arthrogryposis, renal dysfunction, and cholestasis (ARC) syndrome containing mutations in C14orf133 encoding VPS16B revealed pale-appearing platelets in blood films and electron microscopy revealed a complete absence of α-granules, whereas δ-granules were observed. Soluble and membrane-bound α-granule proteins were reduced or undetectable, suggesting that both releasable and membrane-bound α-granule constituents were absent. Immunofluorescence microscopy of Dami cells stably expressing GFP-VPS16B revealed that similar to VPS33B, GFP-VPS16B colocalized with markers of the trans-Golgi network, late endosomes and α-granules. We conclude that VPS16B, similar to its binding partner VPS33B, is essential for megakaryocyte and platelet α-granule biogenesis.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Plaquetas
/
Megacariócitos
/
Proteínas de Transporte
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Vesículas Secretórias
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Proteínas de Transporte Vesicular
Limite:
Female
/
Humans
/
Newborn
Idioma:
En
Revista:
Blood
Ano de publicação:
2012
Tipo de documento:
Article
País de afiliação:
Canadá