Journal Article

The oncoprotein ErbB3 is endocytosed in the absence of added ligand in a clathrin-dependent manner

Malgorzata Magdalena Sak, Kamilla Breen, Sissel Beate Rønning, Nina Marie Pedersen, Vibeke Bertelsen, Espen Stang and Inger Helene Madshus

in Carcinogenesis

Volume 33, issue 5, pages 1031-1039
Published in print May 2012 | ISSN: 0143-3334
Published online March 2012 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/bgs128
The oncoprotein ErbB3 is endocytosed in the absence of added ligand in a clathrin-dependent manner

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The oncoprotein ErbB3 is overexpressed in several human cancers, for example in pancreatic adenocarcinoma and in ovarian cancers, and ErbB3-containing heterodimers have been demonstrated to be potent signaling units in carcinogenesis. This especially applies to ErbB2–ErbB3 and epidermal growth factor receptor (EGFR)–ErbB3 heterodimers providing anti-apoptotic signaling. Relatively little is understood about the signaling of EGFR–ErbB3 heterodimers and especially about mechanisms involved in downregulation of ErbB3 from the plasma membrane. This is in contrast to EGFR homodimers, for which trafficking has been extensively characterized. In the present study, we have investigated mechanisms involved in endocytosis of ErbB3 in porcine aortic endothelial cells stably expressing either ErbB3 only or stably expressing ErbB3 and EGFR. Our data show that ErbB3 is endocytosed in the absence of added ligand, independently of its tyrosine phosphorylation state and in a clathrin-dependent manner. Functional EGFR–ErbB3 heterodimers were observed to be formed, and dimerization with ErbB3 was observed to negatively affect endocytosis of the EGFR.

Journal Article.  6940 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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