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Large G protein α-subunit XLαs limits clathrin-mediated endocytosis and regulates tissue iron levels in vivo.

Abstract：

:Alterations in the activity/levels of the extralarge G protein α-subunit (XLαs) are implicated in various human disorders, such as perinatal growth retardation. Encoded by GNAS, XLαs is partly identical to the α-subunit of the stimulatory G protein (Gsα), but the cellular actions of XLαs remain poorly defined. Following an initial proteomic screen, we identified sorting nexin-9 (SNX9) and dynamins, key components of clathrin-mediated endocytosis, as binding partners of XLαs. Overexpression of XLαs in HEK293 cells inhibited internalization of transferrin, a process that depends on clathrin-mediated endocytosis, while its ablation by CRISPR/Cas9 in an osteocyte-like cell line (Ocy454) enhanced it. Similarly, primary cardiomyocytes derived from XLαs knockout (XLKO) pups showed enhanced transferrin internalization. Early postnatal XLKO mice showed a significantly higher degree of cardiac iron uptake than wild-type littermates following iron dextran injection. In XLKO neonates, iron and ferritin levels were elevated in heart and skeletal muscle, where XLαs is normally expressed abundantly. XLKO heart and skeletal muscle, as well as XLKO Ocy454 cells, showed elevated SNX9 protein levels, and siRNA-mediated knockdown of SNX9 in XLKO Ocy454 cells prevented enhanced transferrin internalization. In transfected cells, XLαs also inhibited internalization of the parathyroid hormone and type 2 vasopressin receptors. Internalization of transferrin and these G protein-coupled receptors was also inhibited in cells expressing an XLαs mutant missing the Gα portion, but not Gsα or an N-terminally truncated XLαs mutant unable to interact with SNX9 or dynamin. Thus, XLαs restricts clathrin-mediated endocytosis and plays a critical role in iron/transferrin uptake in vivo.

journal_name

Proc Natl Acad Sci U S A

journal_title

Proceedings of the National Academy of Sciences of the United States of America

authors

He Q,Bouley R,Liu Z,Wein MN,Zhu Y,Spatz JM,Wang CY,Divieti Pajevic P,Plagge A,Babitt JL,Bastepe M

doi

10.1073/pnas.1712670114

subject

Has Abstract

pub_date

2017-11-07 00:00:00

pages

E9559-E9568

issue

eissn

0027-8424

issn

1091-6490

pii

1712670114

journal_volume

114

pub_type

杂志文章

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Large G protein α-subunit XLαs limits clathrin-mediated endocytosis and regulates tissue iron levels in vivo.