The E3 ligase Itch is a negative regulator of the homeostasis and function of hematopoietic stem cells.
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ABSTRACT:
SUBMITTER: Rathinam C
PROVIDER: S-EPMC8369725 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Hematopoietic stem cells (HSC) are regulated to keep the balance between self-renewal and differentiation. However, little is known about post-translational regulations in HSCs. In this study, we characterize the role of DDB1, a component of the Cul4A-DDB1 E3 ubiquitin ligase complex, in HSCs and progenitors by using conditional DDB1 knockout models. We show that the maintenance and differentiation of both adult and fetal HSCs and progenitor cells is dependent on DDB1 function. Deletion of DDB1 alters cell cycle progression and induces apoptosis. Furthermore, deletion of DDB1 in developing thymocytes had no effects on T cell differentiation, whereas DDB1-deficient peripheral T cells were not able to enter cell cycle when stimulated in vitro. In addition, DDB1 is essential for T cell leukemia initiation. Our results reveal that DDB1 is required for adult and fetal hematopoiesis as it controls progenitor and stem cell homeostasis. Transcriptional consequences of inactivating DDB1 in fetal LSK cells. Four samples were analyzed: wild-type (WT) control and DDB1-deficient (DDB1) Lin-ckit+Sca1+ (LSK) cells sorted from fetal livers E16.5 of DDB1 flox/flox, VavCre+ and control mice.
2015-07-10 | E-GEOD-70658 | biostudies-arrayexpress
Project description:The transcription factor Gli-similar 3 (Glis3) plays a critical role in the generation of pancreatic ß cells and the regulation insulin gene transcription and has been implicated in the development of several pathologies, including type 1 and 2 diabetes and polycystic kidney disease. However, little is known about the proteins and posttranslational modifications that regulate or mediate Glis3 transcriptional activity. In this study, we identify by mass-spectrometry and yeast 2-hybrid analyses several proteins that interact with the N-terminal region of Glis3. These include the WW-domain-containing HECT E3 ubiquitin ligases, Itch, Smurf2, and Nedd4. The interaction between Glis3 and the HECT E3 ubiquitin ligases was verified by co-immunoprecipitation assays and mutation analysis. All three proteins interact through their WW-domains with a PPxY motif located in the Glis3 N-terminus. However, only Itch significantly contributed to Glis3 polyubiquitination and reduced Glis3 stability by enhancing its proteasomal degradation. Itch-mediated degradation of Glis3 required the PPxY motif-dependent interaction between Glis3 and the WW-domains of Itch as well as the presence of the Glis3 zinc finger domains. Transcription analyses demonstrated that Itch dramatically inhibited Glis3-mediated transactivation and endogenous Ins2 expression by increasing Glis3 protein turnover. Taken together, our study identifies Itch as a critical negative regulator of Glis3-mediated transcriptional activity. This regulation provides a novel mechanism to modulate Glis3-driven gene expression and suggests that it may play a role in a number of physiological processes controlled by Glis3, such as insulin transcription, as well as in Glis3-associated diseases.
| S-EPMC4493090 | biostudies-literature
Project description:Hematopoietic stem cells (HSC) are regulated to keep the balance between self-renewal and differentiation. However, little is known about post-translational regulations in HSCs. In this study, we characterize the role of DDB1, a component of the Cul4A-DDB1 E3 ubiquitin ligase complex, in HSCs and progenitors by using conditional DDB1 knockout models. We show that the maintenance and differentiation of both adult and fetal HSCs and progenitor cells is dependent on DDB1 function. Deletion of DDB1 alters cell cycle progression and induces apoptosis. Furthermore, deletion of DDB1 in developing thymocytes had no effects on T cell differentiation, whereas DDB1-deficient peripheral T cells were not able to enter cell cycle when stimulated in vitro. In addition, DDB1 is essential for T cell leukemia initiation. Our results reveal that DDB1 is required for adult and fetal hematopoiesis as it controls progenitor and stem cell homeostasis. Transcriptional consequences of inactivating DDB1 in fetal LSK cells.
2015-07-10 | GSE70658 | GEO
Project description:The Ufm1 conjugation system is a novel ubiquitin-like modification system, consisting of Ufm1, Uba5 (E1), Ufc1 (E2) and poorly characterized E3 ligase(s). RCAD/Ufl1 (also known as KIAA0776, NLBP and Maxer) was reported to function as a Ufm1 E3 ligase in ufmylation (Ufm1-mediated conjugation) of DDRGK1 and ASC1 proteins. It has also been implicated in estrogen receptor signaling, unfolded protein response (UPR) and neurodegeneration, yet its physiological function remains completely unknown. In this study, we report that RCAD/Ufl1 is essential for embryonic development, hematopoietic stem cell (HSC) survival and erythroid differentiation. Both germ-line and somatic deletion of RCAD/Ufl1 impaired hematopoietic development, resulting in severe anemia, cytopenia and ultimately animal death. Depletion of RCAD/Ufl1 caused elevated endoplasmic reticulum stress and evoked UPR in bone marrow cells. In addition, loss of RCAD/Ufl1 blocked autophagic degradation, increased mitochondrial mass and reactive oxygen species, and led to DNA damage response, p53 activation and enhanced cell death of HSCs. Collectively, our study provides the first genetic evidence for the indispensable role of RCAD/Ufl1 in murine hematopoiesis and development. The finding of RCAD/Ufl1 as a key regulator of cellular stress response sheds a light into the role of a novel protein network including RCAD/Ufl1 and its associated proteins in regulating cellular homeostasis.
| S-EPMC4816109 | biostudies-literature
Project description:Nedd4-family E3 ubiquitin ligases regulate an array of biologic processes. Autoinhibition maintains these catalytic ligases in an inactive state through several mechanisms. However, although some Nedd4 family members are activated by binding to Nedd4 family-interacting proteins (Ndfips), how binding activates E3 function remains unclear. Our data reveal how these two regulatory processes are linked functionally. In the absence of Ndfip1, the Nedd4 family member Itch can bind an E2 but cannot accept ubiquitin onto its catalytic cysteine. This is because Itch is autoinhibited by an intramolecular interaction between its HECT (homologous to the E6-AP carboxy terminus domain) and two central WW domains. Ndfip1 binds these WW domains to release the HECT, allowing trans-thiolation and Itch catalytic activity. This molecular switch also regulates the closely related family member WWP2. Importantly, multiple PY motifs are required for Ndfip1 to activate Itch, functionally distinguishing Ndfips from single PY-containing substrates. These data establish a novel mechanism for control of the function of a subfamily of Nedd4 E3 ligases at the level of E2-E3 trans-thiolation.
| S-EPMC4583040 | biostudies-literature
Project description:Mesenchymal stem cells (MSCs) have been highlighted as promising candidate cells in relation to cutaneous wound healing. The current study aimed to investigate whether MSC-derived extracellular vesicles (EVs) could transfer microRNA-27b (miR-27b) to influence cutaneous wound healing. The miR-27b expression was examined in the established cutaneous wound mouse model, and its correlation with the wound healing rate was evaluated by Pearson's correlation analysis. The identified human umbilical cord MSC-derived EVs were co-cultured with human immortal keratinocyte line HaCaT and human skin fibroblasts (HSFs). The mice with cutaneous wound received injections of MSC-derived EVs. The effects of EVs or miR-27b loaded on wound healing and cellular functions were analysed via gain- and loss-of-function approaches in the co-culture system. Dual-luciferase reporter gene assay was employed to verify the relationship between miR-27b and Itchy E3 ubiquitin protein ligase (ITCH). Rescue experiments were conducted to investigate the underlying mechanisms associated with the ITCH/JUNB/inositol-requiring enzyme 1α (IRE1α) axis. miR-27b was down-regulated in the mouse model, with its expression found to be positively correlated with the wound healing rate. Abundant miR-27b was detected in the MSC-derived EVs, while EV-transferred miR-27b improved cutaneous wound healing in mice and improved proliferation and migration of HaCaT cells and HSFs in vitro. As a target of miR-27b, ITCH was found to repress cell proliferation and migration. ITCH enhanced the JUNB ubiquitination and degradation, ultimately inhibiting JUNB and IRE1α expressions and restraining wound healing. Collectively, MSC-derived EVs transferring miR-27b can promote cutaneous wound healing via ITCH/JUNB/IRE1α signalling, providing insight with clinical implications.
| S-EPMC7576224 | biostudies-literature
Project description:Ataxia Telangiectasia Mutated (ATM) kinase, a central regulator of the DNA damage response, regulates the activity of several E3-ubiquitin ligases, and the ubiquitination-proteasome system is a consistent target of ATM. ITCH is an E3-ubiquitin ligase that modulates the ubiquitination of several targets, therefore participating to the regulation of several cellular responses, such as the DNA damage response, tumor necrosis factorα (TNFα), Notch and Hedgehog signaling, and the differentiation of 'naive' lymphocytes into T helper type 2 cells. Here we uncover ATM as a novel positive modulator of ITCH E3-ubiquitin ligase activity. A single residue on ITCH protein, S161, which is part of an ATM SQ consensus motif, is required for ATM-dependent activation of ITCH. ATM activity enhances ITCH enzymatic activity, which in turn drives the ubiquitination and degradation of c-FLIP-L and c-Jun, previously identified as ITCH substrates. Importantly, ATM-deficient mice show resistance to hepatocyte cell death, similarly to Itch-deficient animals, providing in vivo genetic evidence for this circuit. Our data identify ITCH as a novel component of the ATM-dependent signaling pathway and suggest that the impairment of the correct functionality of ITCH caused by Atm deficiency may contribute to the complex clinical features linked to Ataxia Telangiectasia.
| S-EPMC3938399 | biostudies-literature
Project description:OBJECTIVES:Ubiquitin 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. METHODS:We examined the expression levels of E3 ligases and NF-?B 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-?B on Itch expression in C2C12 osteoblast cells was determined by a chromatin immunoprecipitation (ChIP) assay. RESULTS:The 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-?B 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-?B RelA and RelB proteins were found to bind to the NF-?B binding site in the mouse Itch promoter. CONCLUSIONS:Our 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.
| S-EPMC5376659 | biostudies-literature
Project description:Ubiquitination is a posttranslational mechanism that controls diverse cellular processes. We focus here on the ubiquitin ligase Fbw7, a recently identified hematopoietic tumor suppressor that can target for degradation several important oncogenes, including Notch1, c-Myc, and cyclin E. We have generated conditional Fbw7 knockout animals and inactivated the gene in hematopoietic stem cells (HSCs), progenitors, and their differentiated progeny. Deletion of Fbw7 specifically and rapidly affects hematopoiesis in a cell-autonomous manner. Fbw7(-/-) HSCs show defective maintenance of quiescence, leading to impaired self-renewal and a severe loss of competitive repopulating capacity. Furthermore, Fbw7(-/-) progenitors are unable to colonize the thymus, leading to a profound depletion of T cell progenitors. Deletion of Fbw7 in bone marrow (BM) stem cells and progenitors leads to the stabilization of c-Myc, a transcription factor previously implicated in HSC self-renewal. On the other hand, neither Notch1 nor cyclin E is visibly stabilized in the BM of Fbw7-deficient mice. Gene expression studies of Fbw7(-/-) HSCs and hematopoietic progenitors indicate that Fbw7 regulates, through the regulation of HSC cycle entry, the transcriptional "signature" that is associated with the quiescent, self-renewing HSC phenotype.
| S-EPMC2413036 | biostudies-literature
Project description:Follicular helper T cells (T(FH) cells) are responsible for effective B cell-mediated immunity, and Bcl-6 is a central factor for the differentiation of T(FH) cells. However, the molecular mechanisms that regulate the induction of T(FH) cells remain unclear. Here we found that the E3 ubiquitin ligase Itch was essential for the differentiation of T(FH) cells, germinal center responses and immunoglobulin G (IgG) responses to acute viral infection. Itch acted intrinsically in CD4(+) T cells at early stages of T(FH) cell development. Itch seemed to act upstream of Bcl-6 expression, as Bcl-6 expression was substantially impaired in Itch(-/-) cells, and the differentiation of Itch(-/-) T cells into T(FH) cells was restored by enforced expression of Bcl-6. Itch associated with the transcription factor Foxo1 and promoted its ubiquitination and degradation. The defective T(FH) differentiation of Itch(-/-) T cells was rectified by deletion of Foxo1. Thus, our results indicate that Itch acts as an essential positive regulator in the differentiation of T(FH) cells.
| S-EPMC4289613 | biostudies-literature