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The E3 ligase Itch is a negative regulator of the homeostasis and function of hematopoietic stem cells.

ABSTRACT: Although hematopoietic stem cells (HSCs) are the most thoroughly characterized type of adult stem cell, the intricate molecular machinery that regulates their self-renewal properties remains elusive. Here we showed that the E3 ubiquitin ligase Itch negatively regulated the development and function of HSCs. Itch(-/-) mice had HSCs with enhanced frequency, competence and long-term repopulating activity. Itch-deficient HSCs showed accelerated proliferation rates and sustained progenitor properties, as well as more signaling by the transcription factor Notch1, due to more accumulation of activated Notch1. Knockdown of Notch1 in Itch-mutant HSCs resulted in reversion of the phenotype. Thus, we identify Itch as a previously unknown negative regulator of HSC homeostasis and function.

SUBMITTER: Rathinam C

PROVIDER: S-EPMC8369725 | biostudies-literature | 2011 May

REPOSITORIES: biostudies-literature

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The E3 ligase Itch is a negative regulator of the homeostasis and function of hematopoietic stem cells.

Rathinam Chozhavendan C Matesic Lydia E LE Flavell Richard A RA

Nature immunology 20110410 5

Although hematopoietic stem cells (HSCs) are the most thoroughly characterized type of adult stem cell, the intricate molecular machinery that regulates their self-renewal properties remains elusive. Here we showed that the E3 ubiquitin ligase Itch negatively regulated the development and function of HSCs. Itch(-/-) mice had HSCs with enhanced frequency, competence and long-term repopulating activity. Itch-deficient HSCs showed accelerated proliferation rates and sustained progenitor properties, ...[more]

PMID: 21478879

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Project description:ObjectivesUbiquitin E3 ligase-mediated protein degradation regulates osteoblast function. Itch, an E3 ligase, affects numerous cell functions by regulating ubiquitination and proteasomal degradation of related proteins. However, the Itch-related cellular and molecular mechanisms by which osteoblast differentiation and function are elevated during bone fracture repair are as yet unknown.MethodsWe examined the expression levels of E3 ligases and NF-κB members in callus samples during bone fracture repair by quantitative polymerase chain reaction (qPCR) and the total amount of ubiquitinated proteins by Western blot analysis in wild-type (WT) mice. The expression levels of osteoblast-associated genes in fracture callus from Itch knockout (KO) mice and their WT littermates were examined by qPCR. The effect of NF-κB on Itch expression in C2C12 osteoblast cells was determined by a chromatin immunoprecipitation (ChIP) assay.ResultsThe expression levels of WW Domain Containing E3 Ubiquitin Protein Ligase 1 (Wwp1), SMAD Specific E3 Ubiquitin Protein Ligase 1 (Smurf1), SMAD Specific E3 Ubiquitin Protein Ligase 2 (Smurf2) and Itch were all significantly increased in the fracture callus of WT mice, which was associated with elevated expression of NF-κB members and total ubiquitinated proteins. Callus tissue isolated from Itch KO mice expressed higher levels of osteoblast-associated genes, including Runx2, a positive regulator of osteoblast differentiation, but osteoclast-associated genes were not increased. Both NF-κB RelA and RelB proteins were found to bind to the NF-κB binding site in the mouse Itch promoter.ConclusionsOur findings indicate that Itch depletion may have a strong positive effect on osteoblast differentiation in fracture callus. Thus, ubiquitin E3 ligase Itch could be a potential target for enhancing bone fracture healing.Cite this article: J. Liu, X. Li, H. Zhang, R. Gu, Z. Wang, Z. Gao, L. Xing. Ubiquitin E3 ligase Itch negatively regulates osteoblast function by promoting proteasome degradation of osteogenic proteins. Bone Joint Res 2017;6:154-161. DOI: 10.1302/2046-3758.63.BJR-2016-0237.R1.

Dataset Information

The E3 ligase Itch is a negative regulator of the homeostasis and function of hematopoietic stem cells.

Publications

The E3 ligase Itch is a negative regulator of the homeostasis and function of hematopoietic stem cells.

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