Cbl ubiquitination of p85 is essential for Epo-induced EpoR endocytosis.

Gamze B. Bulut, Rita Sulahian, Huiyu Yao, Lily Jun shen Huang

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Erythropoietin (Epo) binding to the Epo receptor (EpoR) elicits downstream signaling that is essential for red blood cell production. One important negative regulatory mechanism to terminate Epo signaling is Epo-induced EpoR endocytosis and degradation. Defects in this mechanism play a key role in the overproduction of erythrocytes in primary familial and congenital polycythemia (PFCP). Here we have identified a novel mechanism mediating Epo-dependent EpoR internalization. Epo induces Cbl-dependent ubiquitination of the p85 regulatory subunit of PI3K, which binds to phosphotyrosines on EpoR. Ubiquitination allows p85 to interact with the endocytic protein epsin-1, thereby driving EpoR endocytosis. Knockdown of Cbl, expression of its dominant negative forms, or expression of an epsin-1 mutant devoid of ubiquitin-interacting motifs all compromise Epo-induced EpoR internalization. Mutated EpoRs mimicking those from PFCP patients cannot bind p85, co-localize with epsin-1, or internalize on Epo stimulation and exhibit Epo hypersensitivity. Similarly, knockdown of Cbl also causes Epo hypersensitivity in primary erythroid progenitors. Restoring p85 binding to PFCP receptors rescues Epo-induced epsin-1 co-localization and EpoR internalization and normalizes Epo hypersensitivity. Our results uncover a novel Cbl/p85/epsin-1 pathway in EpoR endocytosis and show that defects in this pathway contribute to excessive Epo signaling and erythroid hyperproliferation in PFCP.

Original languageEnglish (US)
Pages (from-to)3964-3972
Number of pages9
JournalBlood
Volume122
Issue number24
StatePublished - Dec 5 2013

Fingerprint

Ubiquitination
Erythropoietin
Endocytosis
Erythropoietin Receptors
Hypersensitivity
Erythrocytes
Phosphotyrosine
Defects
Ubiquitin
Phosphatidylinositol 3-Kinases
Blood
epsin
Cells

ASJC Scopus subject areas

  • Hematology
  • Biochemistry
  • Cell Biology
  • Immunology
  • Medicine(all)

Cite this

Bulut, G. B., Sulahian, R., Yao, H., & Huang, L. J. S. (2013). Cbl ubiquitination of p85 is essential for Epo-induced EpoR endocytosis. Blood, 122(24), 3964-3972.

Cbl ubiquitination of p85 is essential for Epo-induced EpoR endocytosis. / Bulut, Gamze B.; Sulahian, Rita; Yao, Huiyu; Huang, Lily Jun shen.

In: Blood, Vol. 122, No. 24, 05.12.2013, p. 3964-3972.

Research output: Contribution to journalArticle

Bulut, GB, Sulahian, R, Yao, H & Huang, LJS 2013, 'Cbl ubiquitination of p85 is essential for Epo-induced EpoR endocytosis.', Blood, vol. 122, no. 24, pp. 3964-3972.
Bulut GB, Sulahian R, Yao H, Huang LJS. Cbl ubiquitination of p85 is essential for Epo-induced EpoR endocytosis. Blood. 2013 Dec 5;122(24):3964-3972.
Bulut, Gamze B. ; Sulahian, Rita ; Yao, Huiyu ; Huang, Lily Jun shen. / Cbl ubiquitination of p85 is essential for Epo-induced EpoR endocytosis. In: Blood. 2013 ; Vol. 122, No. 24. pp. 3964-3972.
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