Quantitative proteomics of MDCK cells identify unrecognized roles of clathrin adaptor AP-1 in polarized distribution of surface proteins.

Autor:	Caceres PS; Margaret Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medical College, New York, NY 10065., Gravotta D; Margaret Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medical College, New York, NY 10065., Zager PJ; Margaret Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medical College, New York, NY 10065., Dephoure N; Department of Biochemistry, Weill Cornell Medical College, New York, NY 10021., Rodriguez-Boulan E; Margaret Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medical College, New York, NY 10065; boulan@med.cornell.edu.
Jazyk:	angličtina
Zdroj:	Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2019 Jun 11; Vol. 116 (24), pp. 11796-11805. Date of Electronic Publication: 2019 May 29.
DOI:	10.1073/pnas.1821076116
Abstrakt:	The current model of polarized plasma membrane protein sorting in epithelial cells has been largely generated on the basis of experiments characterizing the polarized distribution of a relatively small number of overexpressed model proteins under various experimental conditions. Thus, the possibility exists that alternative roles of various types of sorting machinery may have been underestimated or missed. Here, we utilize domain-selective surface biotinylation combined with stable isotope labeling with amino acids in cell culture (SILAC) and mass spectrometry to quantitatively define large populations of apical and basolateral surface proteins in Madin-Darby canine kidney (MDCK) cells. We identified 313 plasma membrane proteins, of which 38% were apical, 51% were basolateral, and 11% were nonpolar. Silencing of clathrin adaptor proteins (AP) AP-1A, AP-1B, or both caused redistribution of basolateral proteins as expected but also, of a large population of apical proteins. Consistent with their previously reported ability to compensate for one another, the strongest loss of polarity was observed when we silenced AP-1A and AP-1B simultaneously. We found stronger evidence of compensation in the apical pathway compared with the basolateral pathway. Surprisingly, we also found subgroups of proteins that were affected after silencing just one adaptor, indicating previously unrecognized independent roles for AP-1A and AP-1B. While AP-1B silencing mainly affected basolateral polarity, AP-1A silencing seemed to cause comparable loss of apical and basolateral polarity. Our results uncover previously overlooked roles of AP-1 in polarized distribution of apical and basolateral proteins and introduce surface proteomics as a method to examine mechanisms of polarization with a depth not possible until now. Competing Interests: The authors declare no conflict of interest. (Copyright © 2019 the Author(s). Published by PNAS.)
Databáze:	MEDLINE
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