scholarly journals A proteasomal partner goes missing in Angelman syndrome

2018 ◽  
Vol 293 (47) ◽  
pp. 18400-18401
Author(s):  
Jon M. Huibregtse
Keyword(s):  
Ubiquitin Ligase ◽  
Angelman Syndrome ◽  
Loss Of Function ◽  
Neurologic Disorder ◽  
Direct Binding

Loss-of-function mutations in the UBE3A ubiquitin ligase are associated with Angelman syndrome (AS), a severe neurologic disorder. A new study defines the role of mutations in an N-terminal “AZUL” domain as mediating direct binding to a proteasomal subunit and shows that this interaction is correlated with the ability of UBE3A to promote Wnt/β-catenin signaling. These results provide new insights into a central biomolecule in AS and suggest that defects in Wnt/β-catenin signaling may underlie some AS phenotypes.

scholarly journals Loss-of-function of Fbxo10, encoding a post-translational regulator of BCL2 in lymphomas, has no discernible effect on BCL2 or B lymphocyte accumulation in mice

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0237830
Author(s):  
Etienne Masle-Farquhar ◽  
Amanda Russell ◽  
Yangguang Li ◽  
Fen Zhu ◽  
Lixin Rui ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Ubiquitin Ligase ◽  
Single Gene ◽  
Mutant Mice ◽  
Loss Of Function ◽  
B Cell Lymphomas ◽  
Truncating Mutation ◽  
Bcl2 Protein

Regulation of the anti-apoptotic BCL2 protein determines cell survival and is frequently abnormal in B cell lymphomas. An evolutionarily conserved post-translational mechanism for over-expression of BCL2 in human B cell lymphomas and the BCL2 paralogue CED-9 in Caenorhabditis elegans results from loss-of-function mutations in human FBXO10 and its C.elegans paralogue DRE-1, a BCL2/CED-9-binding subunit of the SKP-CULLIN-FBOX (SCF) ubiquitin ligase. Here, we tested the role of FBXO10 in BCL2 regulation by producing mice with two different CRISPR/Cas9-engineered Fbxo10 mutations: an Asp54Lys (E54K) missense mutation in the FBOX domain and a Cys55SerfsTer55 frameshift (fs) truncating mutation. Mice homozygous for either mutant allele were born at the expected Mendelian frequency and appeared normal in body weight and appearance as adults. Spleen B cells from homozygous mutant mice did not have increased BCL2 protein, nor were the numbers of mature B cells or germinal centre B cells increased as would be expected if BCL2 was increased. Other lymphocyte subsets that are also regulated by BCL2 levels also displayed no difference in frequency in homozygous Fbxo10 mutant mice. These results support one of two conclusions: either FBXO10 does not regulate BCL2 in mice, or it does so redundantly with other ubiquitin ligase complexes. Possible candidates for the latter include FBXO11 or ARTS-XIAP. The difference between the role of FBXO10 in regulating BCL2 protein levels in C. elegans and in human DLBCL, relative to single-gene deficient mouse leukocytes, should be further investigated.

scholarly journals KLF5-mediated EPPK1 Expression Promotes Cell Proliferation in Cervical Cancer via the P38 Signaling Pathway

2020 ◽  
Author(s):  
Zhe Pan ◽  
Xiao Liu ◽  
Quan Chang ◽  
Jin-jin Zhang ◽  
Na Hua ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Cell Proliferation ◽  
Signaling Pathway ◽  
Cell Lines ◽  
Immunofluorescence Staining ◽  
Rna Seq ◽  
Loss Of Function ◽  
Cytoskeleton Reorganization ◽  
Direct Binding

Abstract Background: Epiplakin1 (Eppk1) is part of the EGF signal and is involved in cytoskeleton reorganization and cell proliferation. However, the role of Eppk1 in cervical cancer remains unknown. Methods: The expression of Eppk1 and KLF5 as well as their correlation were assessed by RNA-seq, qRT-PCR, TCGA database and immunofluorescence staining. In CC cell lines, adenovirus-mediated overexpression or knockdown of KLF5 and Eppk1 as well as corresponding assessment of cell proliferation and signaling were determined by western blot and CCK8 experiments. Assays of lucifase reporter gene and CHIP were used to investigate mechanism between KLF5 and Eppk1. Results: Eppk1 expression was markedly in CC tissues and cell lines companied by KLF5 upregulation. The results of immunofluorescence staining further showed that the increased expression of Eppk1 and KLF5 correlated with progression of cervical tumorigenesis. Overexpression of KLF5 significantly increased Eppk1 expression at transcription and translation levels. Conversely, the knockdown of KLF5 by siRNA against KLF5 decreased Eppk1 expression. Mechanical studies showed that KLF5 activated Eppk1 transcription by direct binding to the Eppk1 promoter. Gain- and loss-of-function experiments showed that KLF5 promoted cell proliferation in Hela by upregulating Eppk1 expression. Moreover, KLF5-mediated the activation of EGFR and p38 signaling significantly decreased after Eppk1 knockdown companied with reduction of proliferating activity, suggesting that Eppk1 lies upstream of p38 signaling affecting cell proliferation in CC. Finally, the expression of Eppk1 positively correlated with tumor size. Conclusions: Eppk1 may be an effective therapeutic target on affecting EGFR-associated p38 signaling pathway and cell proliferation in cervical cancer.

scholarly journals Deleting a UBE3A substrate rescues impaired hippocampal physiology and learning in Angelman syndrome mice

2019 ◽  
Author(s):  
Gabrielle L. Sell ◽  
Wendy Xin ◽  
Emily K. Cook ◽  
Mark A. Zbinden ◽  
Thomas B. Schaffer ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Angelman Syndrome ◽  
Developmental Disorders ◽  
Motor Coordination ◽  
Synapse Formation ◽  
Neurodevelopmental Disorder ◽  
Autism Spectrum ◽  
Loss Of Function ◽  
Altered Expression ◽  
Exciting Potential

ABSTRACTIn humans, loss-of-function mutations in the UBE3A gene lead to the neurodevelopmental disorder Angelman syndrome (AS). AS patients have severe impairments in speech, learning and memory, and motor coordination, for which there is currently no treatment. In addition, UBE3A is duplicated in >1-2% of patients with autism spectrum disorders – a further indication of the significant role it plays in brain development. Altered expression of UBE3A, an E3 ubiquitin ligase, is hypothesized to lead to impaired levels of its target proteins, but identifying the contribution of individual UBE3A targets to UBE3A-dependent deficits remains of critical importance. Ephexin5 is a putative UBE3A substrate that has restricted expression early in development, regulates synapse formation during hippocampal development, and is abnormally elevated in AS mice, modeled by maternally-derived Ube3a gene deletion. Here, we report that Ephexin5 is a direct substrate of UBE3A ubiquitin ligase activity. Furthermore, removing Ephexin5 from AS mice specifically rescued hippocampus-dependent behaviors, CA1 physiology, and deficits in dendritic spine number. Our findings identify Ephexin5 as a key driver of hippocampal dysfunction and related behavioral deficits in AS mouse models. These results demonstrate the exciting potential of targeting Ephexin5, and possibly other UBE3A substrates, to improve symptoms of AS and other UBE3A-related developmental disorders.

scholarly journals KLF5-mediated Eppk1 expression promotes cell proliferation in cervical cancer via the  p38 signaling pathway

2020 ◽  
Author(s):  
Zhe Pan ◽  
Xiao Liu ◽  
Quan Chang ◽  
Jin-jin Zhang ◽  
Na Hua ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Cell Proliferation ◽  
Signaling Pathway ◽  
Cell Lines ◽  
Immunofluorescence Staining ◽  
Rna Seq ◽  
Loss Of Function ◽  
Cytoskeleton Reorganization ◽  
Direct Binding

Abstract Background: Epiplakin1 (Eppk1) is part of the EGF signal and is involved in cytoskeleton reorganization and cell proliferation. However, the role of Eppk1 in cervical cancer remains unknown. Objective: To determine the role of EPPK1 on cell proliferation in cervical cancer. Methods: The expression of Eppk1 and KLF5 as well as their correlation were assessed by RNA-seq, qRT-PCR, TCGA database and immunofluorescence staining. In CC cell lines, adenovirus-mediated overexpression or knockdown of KLF5 and Eppk1 as well as corresponding assessment of cell proliferation and signaling were determined by western blot and CCK8 experiments. Assays of lucifase reporter gene and CHIP were used to investigate mechanism between KLF5 and Eppk1 . Results: Eppk1 expression was markedly in CC tissues and cell lines companied by KLF5 upregulation. The results of immunofluorescence staining further showed that the increased expression of Eppk1 and KLF5 correlated with progression of cervical tumorigenesis. Overexpression of KLF5 significantly increased Eppk1 expression at transcription and translation levels. Conversely, the knockdown of KLF5 by siRNA against KLF5 decreased Eppk1 expression. Mechanical studies showed that KLF5 activated Eppk1 transcription by direct binding to the Eppk1 promoter. Gain- and loss-of-function experiments showed that KLF5 promoted cell proliferation in Hela by upregulating Eppk1 expression. Moreover, KLF5-mediated the activation of EGFR and p38 signaling significantly decreased after Eppk1 knockdown companied with reduction of proliferating activity, suggesting that Eppk1 lies upstream of p38 signaling affecting cell proliferation in CC. Finally, the expression of Eppk1 positively correlated with tumor size. Conclusions: Eppk1 may be an effective therapeutic target on affecting EGFR-associated p38 signaling pathway and cell proliferation in cervical cancer.

scholarly journals Role of the RNA-Binding Protein IMP-2 in Muscle Cell Motility

2010 ◽  
Vol 30 (24) ◽  
pp. 5710-5725 ◽  
Author(s):  
Selim Boudoukha ◽  
Sylvain Cuvellier ◽  
Anna Polesskaya
Keyword(s):  
Cell Motility ◽  
Posttranscriptional Regulation ◽  
Rna Binding ◽  
Regulation Of Gene Expression ◽  
Cellular Motility ◽  
Loss Of Function ◽  
Skeletal Myoblasts ◽  
Direct Binding ◽  
Mrna Binding

ABSTRACT Insulin-like growth factor 2 (IGF-2) mRNA-binding proteins (IMPs) are a family of posttranscriptional regulatory factors with well-understood roles in embryonic development and cancer but with poorly characterized functions in normal adult cells and tissues. We now show that IMP-2, the most ubiquitously expressed member of the family, is abundant in human and mouse adult skeletal myoblasts, where it is indispensable for cell motility and for stabilization of microtubules. To explore the functions of IMP-2, we analyzed the transcripts that were differentially regulated in IMP-2-depleted myoblasts and bound to IMP-2 in normal myoblasts. Among them were the mRNAs of PINCH-2, an important mediator of cell adhesion and motility, and MURF-3, a microtubule-stabilizing protein. By gain- and loss-of-function assays and gel shift experiments, we show that IMP-2 regulates the expression of PINCH-2 and MURF-3 proteins via direct binding to their mRNAs. Upregulation of PINCH-2 in IMP-2-depleted myoblasts is the key event responsible for their decreased motility. Our data reveal how the posttranscriptional regulation of gene expression by IMP-2 contributes to the control of adhesion structures and stable microtubules and demonstrate an important function for IMP-2 in cellular motility.

scholarly journals Loss-of-function of Fbxo10, encoding a post-translational regulator of BCL2 in lymphomas, has no discernible effect on BCL2 or B lymphocyte accumulation in mice

2020 ◽  
Author(s):  
Etienne Masle-Farquhar ◽  
Amanda Russell ◽  
Yangguang Li ◽  
Fen Zhu ◽  
Lixin Rui ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Ubiquitin Ligase ◽  
Single Gene ◽  
Mutant Mice ◽  
Loss Of Function ◽  
B Cell Lymphomas ◽  
Truncating Mutation ◽  
Bcl2 Protein

AbstractRegulation of the anti-apoptotic BCL2 protein determines cell survival and is frequently abnormal in B cell lymphomas. An evolutionarily conserved post-translational mechanism for over-expression of BCL2 in human B cell lymphomas and the BCL2 paralogue CED-9 in Caenorhabditis elegans results from loss-of-function mutations in human FBXO10 and its C.elegans paralogue DRE-1, a BCL2/CED-9-binding subunit of the SKP-CULLIN-FBOX (SCF) ubiquitin ligase. Here, we tested the role of FBXO10 in BCL2 regulation by producing mice with two different CRISPR/Cas9-engineered Fbxo10 mutations: an Asp54Lys (E54K) missense mutation in the FBOX domain and a Cys55SerfsTer55 frameshift (fs) truncating mutation. Mice homozygous for either mutant allele were born at the expected Mendelian frequency and appeared normal in body weight and appearance as adults. Spleen B cells from homozygous mutant mice did not have increased BCL2 protein, nor were the numbers of mature B cells or germinal centre B cells increased as would be expected if BCL2 was increased. Other lymphocyte subsets that are also regulated by BCL2 levels also displayed no difference in frequency in homozygous Fbxo10 mutant mice. These results support one of two conclusions: either FBXO10 does not regulate BCL2 in mice, or it does so redundantly with other ubiquitin ligase complexes. Possible candidates for the latter include FBXO11 or ARTS-XIAP. The difference between the role of FBXO10 in regulating BCL2 protein levels in C. elegans and in human DLBCL, relative to single-gene deficient mouse leukocytes, should be further investigated.

scholarly journals KLF5-mediated Eppk1 expression promotes cell proliferation in cervical cancer via the  p38 signaling pathway

2020 ◽  
Author(s):  
Zhe Pan ◽  
Xiao Liu ◽  
Quan Chang ◽  
Jin-jin Zhang ◽  
Na Hua ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Cell Proliferation ◽  
Signaling Pathway ◽  
Cell Lines ◽  
Immunofluorescence Staining ◽  
Rna Seq ◽  
Loss Of Function ◽  
Cytoskeleton Reorganization ◽  
Direct Binding

Abstract Background: Epiplakin1 (Eppk1) is part of the EGF signal and is involved in cytoskeleton reorganization and cell proliferation. However, the role of Eppk1 in cervical cancer remains unknown.Objective: To determine the role of EPPK1 on cell proliferation in cervical cancer.Methods: The expression of Eppk1 and KLF5 as well as their correlation were assessed by RNA-seq, qRT-PCR, TCGA database and immunofluorescence staining. In CC cell lines, adenovirus-mediated overexpression or knockdown of KLF5 and Eppk1 as well as corresponding assessment of cell proliferation and signaling were determined by western blot and CCK8 experiments. Assays of lucifase reporter gene and CHIP were used to investigate mechanism between KLF5 and Eppk1.Results: Eppk1 expression was markedly in CC tissues and cell lines companied by KLF5 upregulation. The results of immunofluorescence staining further showed that the increased expression of Eppk1 and KLF5 correlated with progression of cervical tumorigenesis. Overexpression of KLF5 significantly increased Eppk1 expression at transcription and translation levels. Conversely, the knockdown of KLF5 by siRNA against KLF5 decreased Eppk1 expression. Mechanical studies showed that KLF5 activated Eppk1 transcription by direct binding to the Eppk1 promoter. Gain- and loss-of-function experiments showed that KLF5 promoted cell proliferation in Hela by upregulating Eppk1 expression. Moreover, KLF5-mediated the activation of EGFR and p38 signaling significantly decreased after Eppk1 knockdown companied with reduction of proliferating activity, suggesting that Eppk1 lies upstream of p38 signaling affecting cell proliferation in CC. Finally, the expression of Eppk1 positively correlated with tumor size.Conclusions: Eppk1 may be an effective therapeutic target on affecting EGFR-associated p38 signaling pathway and cell proliferation in cervical cancer.

scholarly journals A family harboring an MLKL loss of function variant implicates impaired necroptosis in diabetes

2021 ◽  
Vol 12 (4) ◽  
Author(s):  
Joanne M. Hildebrand ◽  
Bernice Lo ◽  
Sara Tomei ◽  
Valentina Mattei ◽  
Samuel N. Young ◽  
...  
Keyword(s):  
Potential Role ◽  
Autosomal Dominant ◽  
Inflammatory Diseases ◽  
Diabetic Patients ◽  
Incomplete Penetrance ◽  
Loss Of Function ◽  
Healthy Sibling ◽  
Dominant Disease ◽  
Terminal Effector

AbstractMaturity-onset diabetes of the young, MODY, is an autosomal dominant disease with incomplete penetrance. In a family with multiple generations of diabetes and several early onset diabetic siblings, we found the previously reported P33T PDX1 damaging mutation. Interestingly, this substitution was also present in a healthy sibling. In contrast, a second very rare heterozygous damaging mutation in the necroptosis terminal effector, MLKL, was found exclusively in the diabetic family members. Aberrant cell death by necroptosis is a cause of inflammatory diseases and has been widely implicated in human pathologies, but has not yet been attributed functions in diabetes. Here, we report that the MLKL substitution observed in diabetic patients, G316D, results in diminished phosphorylation by its upstream activator, the RIPK3 kinase, and no capacity to reconstitute necroptosis in two distinct MLKL−/− human cell lines. This MLKL mutation may act as a modifier to the P33T PDX1 mutation, and points to a potential role of impairment of necroptosis in diabetes. Our findings highlight the importance of family studies in unraveling MODY’s incomplete penetrance, and provide further support for the involvement of dysregulated necroptosis in human disease.

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