Ubc13 and COOH Terminus of Hsp70-interacting Protein (CHIP) Are Required for Growth Hormone Receptor Endocytosis

• Published in: The Journal of biological chemistry Vol. 287; no. 19; pp. 15533 - 15543
• Main Authors: Slotman, Johan A., da Silva Almeida, Ana C., Hassink, Gerco C., van de Ven, Robert H.A., van Kerkhof, Peter, Kuiken, Hendrik J., Strous, Ger J.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 04.05.2012; American Society for Biochemistry and Molecular Biology
• Subjects: beta-Transducin Repeat-Containing Proteins - genetics; beta-Transducin Repeat-Containing Proteins - metabolism; Blotting, Western; Cell Biology; Cell Line, Tumor; CHIP; E3 Ubiquitin Ligase; Endocytosis; GHR; Growth Hormone; Humans; Lys63-linked Ubiquitin; Lysine - metabolism; Microscopy, Fluorescence; Protein Binding; Protein Multimerization; Receptor Desensitization; Receptor Endocytosis; Receptors, Somatotropin - chemistry; Receptors, Somatotropin - genetics; Receptors, Somatotropin - metabolism; RNA Interference; Ubc13; Ubiquitin-conjugating Enzyme (Ubc); Ubiquitin-Conjugating Enzymes - genetics; Ubiquitin-Conjugating Enzymes - metabolism; Ubiquitin-Protein Ligases - genetics; Ubiquitin-Protein Ligases - metabolism; Ubiquitination; GHR; E3 Ubiquitin Ligase; Lys63-linked Ubiquitin; Ubiquitin-conjugating Enzyme (Ubc); Endocytosis; CHIP; Ubc13; Growth Hormone; Receptor Desensitization; Receptor Endocytosis
• ISSN: 0021-9258; 1083-351X; 1083-351X
• DOI: 10.1074/jbc.M111.302521

Growth hormone receptor (GHR) endocytosis is a highly regulated process that depends on the binding and activity of the multimeric ubiquitin ligase, SCFβTrCP (Skp Cullin F-box). Despite a specific interaction between β-transducin repeat-containing protein (βTrCP) and the GHR, and a strict requirement for ubiquitination activity, the receptor is not an obligatory target for SCFβTrCP-directed Lys48 polyubiquitination. We now show that also Lys63-linked ubiquitin chain formation is required for GHR endocytosis. We identified both the ubiquitin-conjugating enzyme Ubc13 and the ubiquitin ligase COOH terminus of Hsp70 interacting protein (CHIP) as being connected to this process. Ubc13 activity and its interaction with CHIP precede endocytosis of GHR. In addition to βTrCP, CHIP interacts specifically with the cytosolic tails of the dimeric GHR, identifying both Ubc13 and CHIP as novel factors in the regulation of cell surface availability of GHR. Background: The scientific question that we address is how cytokine receptors organize their degradation. Results: CHIP and Ubc13 are required for GH receptor endocytosis, implicating Lys63-specific ubiquitination. Conclusion: This study shows how two ubiquitin ligases act in concert to allow receptor endocytosis. Significance: Understanding this mechanism enables drug design to control GH signaling in fighting cancer and cachexia.