scholarly journals VBP1 modulates Wnt/β-catenin signaling by mediating the stability of the transcription factors TCF/LEFs

2020 ◽  
Vol 295 (49) ◽  
pp. 16826-16839
Author(s):  
Haifeng Zhang ◽  
Xiaozhi Rong ◽  
Caixia Wang ◽  
Yunzhang Liu ◽  
Ling Lu ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Protein Stability ◽  
Signaling Pathway ◽  
Cultured Cells ◽  
Critical Role ◽  
Family Members ◽  
Von Hippel Lindau ◽  
T Cell Factor ◽  
Protein Levels ◽  
The Stability

The Wnt/β-catenin pathway is one of the major pathways that regulates embryonic development, adult homeostasis, and stem cell self-renewal. In this pathway, transcription factors T-cell factor and lymphoid enhancer factor (TCF/LEF) serve as a key switch to repress or activate Wnt target gene transcription by recruiting repressor molecules or interacting with the β-catenin effector, respectively. It has become evident that the protein stability of the TCF/LEF family members may play a critical role in controlling the activity of the Wnt/β-catenin signaling pathway. However, factors that regulate the stability of TCF/LEFs remain largely unknown. Here, we report that pVHL binding protein 1 (VBP1) regulates the Wnt/β-catenin signaling pathway by controlling the stability of TCF/LEFs. Surprisingly, we found that either overexpression or knockdown of VBP1 decreased Wnt/β-catenin signaling activity in both cultured cells and zebrafish embryos. Mechanistically, VBP1 directly binds to all four TCF/LEF family members and von Hippel-Lindau tumor-suppressor protein (pVHL). Either overexpression or knockdown of VBP1 increases the association between TCF/LEFs and pVHL and then decreases the protein levels of TCF/LEFs via proteasomal degradation. Together, our results provide mechanistic insights into the roles of VBP1 in controlling TCF/LEFs protein stability and regulating Wnt/β-catenin signaling pathway activity.

scholarly journals Activity of the β-catenin phosphodestruction complex at cell–cell contacts is enhanced by cadherin-based adhesion

2009 ◽  
Vol 186 (2) ◽  
pp. 219-228 ◽  
Author(s):  
Meghan T. Maher ◽  
Annette S. Flozak ◽  
Adam M. Stocker ◽  
Anjen Chenn ◽  
Cara J. Gottardi
Keyword(s):  
Transcription Factors ◽  
Cell Adhesion ◽  
Cell Fate ◽  
Cell Contacts ◽  
Cell Fate Decisions ◽  
T Cell Factor ◽  
Protein Levels ◽  
Gsk 3Β ◽  
Canonical Wnt ◽  
Cell Cell

It is well established that cadherin protein levels impact canonical Wnt signaling through binding and sequestering β-catenin (β-cat) from T-cell factor family transcription factors. Whether changes in intercellular adhesion can affect β-cat signaling and the mechanism through which this occurs has remained unresolved. We show that axin, APC2, GSK-3β and N-terminally phosphorylated forms of β-cat can localize to cell–cell contacts in a complex that is molecularly distinct from the cadherin–catenin adhesive complex. Nonetheless, cadherins can promote the N-terminal phosphorylation of β-cat, and cell–cell adhesion increases the turnover of cytosolic β-cat. Together, these data suggest that cadherin-based cell–cell adhesion limits Wnt signals by promoting the activity of a junction-localized β-cat phosphodestruction complex, which may be relevant to tissue morphogenesis and cell fate decisions during development.

scholarly journals Reconstitution of the Jasmonate Signaling Pathway in Plant Protoplasts

Cells ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1532 ◽  
Author(s):  
Ning Li ◽  
Joachim F. Uhrig ◽  
Corinna Thurow ◽  
Li-Jun Huang ◽  
Christiane Gatz
Keyword(s):  
Signaling Pathway ◽  
Function Analysis ◽  
Luciferase Reporter ◽  
Luciferase Reporter Gene ◽  
Protein Levels ◽  
Activation Of Transcription ◽  
Subsequent Degradation ◽  
The Stability ◽  
F Box Protein ◽  
Ja Signaling

The phytohormone jasmonic acid (JA) plays an important role in various plant developmental processes and environmental adaptations. The JA signaling pathway has been well-elucidated in the reference plant Arabidopsis thaliana. It starts with the perception of the active JA derivative, jasmonoyl-isoleucine (JA-Ile), by the F-box protein COI1 which is part of the E3-ligase SCFCOI1. Binding of JA-Ile enables the interaction between COI1 and JAZ repressor proteins. Subsequent degradation of JAZ proteins leads to the activation of transcription factors like e.g., MYC2. Here we demonstrate that the pathway can be reconstituted in transiently transformed protoplasts. Analysis of the stability of a JAZ1-fLuc fusion protein as a function of COI1 transiently expressed in coi1 protoplasts allows structure function analysis of both JAZs and COI1. Using this system, we found that conserved cysteines in COI1 influence steady state COI1 protein levels. Using a luciferase reporter gene under the control of the JAZ1 promoter enable to address those features of JAZ1 that are required for MYC2 repression. Interestingly, the conserved TIFY-motif previously described to interact with NINJA to recruit the corepressor TOPLESS is not necessary for repression. This result is in favor of the alternative repression mode that proposes a direct competition between repressive JAZs and promotive MEDIATOR25 at MYC2. Finally, using protoplasts from the aos coi1 double mutant, which is deficient in JA synthesis and perception, we provide a system that has the potential to study the activity of different COI1 variants in the presence of different ligands.

Abstract 239: Selective Class I and II Histone Deacetylation Inhibitors Alter Stability of HDAC-Corepressor Complexes

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Hsiao C Wang ◽  
Lillianne G Harris ◽  
James C Chou ◽  
Santhosh Mani ◽  
Donald Menick
Keyword(s):  
Heart Failure ◽  
Transcription Factor ◽  
Transcription Factors ◽  
Cardiac Hypertrophy ◽  
Critical Role ◽  
Hdac Inhibitors ◽  
Class I ◽  
Proximal Promoter ◽  
Repressor Complex ◽  
The Stability

Introduction: Alterations in expression and activity of different genes have been implicated in the pathogenesis of heart failure. Our lab has shown that HDAC-repressor complexes play a critical role in the upregulation Sodium Calcium Exchanger ( Ncx1) and HDAC inhibition causes changes that attenuated cardiac remodeling during cardiac hypertrophy and heart failure. Thus, treatment with HDAC inhibitors has been proposed as a potential strategy for treatment of cardiac hypertrophy and heart failure. HDAC inhibitors repress deacetylase activity but we propose that they also affect HDAC confirmation and interaction with other protein factors. We hypothesize that HDAC inhibitors affect the stability of the co-repressor complex with specific transcription factors and that this effect is dependent on the transcription factor. Results: Inhibition of HDACs in adult cardiomyocytes results in the greater stabilization of HDACs with co-repressor molecules that were recruited to the NCX1 promoter through Nkx2.5 transcription factor. HDAC class I specific inhibitor, MS 275 demonstrated stronger association between HDACs and co-repressors while other Class I inhibitors, PD106 and BML 210 failed on showing this phenomenal. The results suggested that class I HDACs inhibitors may affect formations of HDAC-complex via alternated active site interactions other than chelating with zinc binding domain. These results compliment ChIP experiments which also demonstrate the different recruitments of Sin3a at the proximal promoter of NCX1. In vivo analysis on HDAC5 knockout mice reveal that the Sin3a-HDAC1/2 repressor complex is not recruited to the Ncx1 promoter in the absence of HDAC5, indicating not only Class I HDAC but also Class II HDACs play an important role on HDAC-complex formation. Conclusions: This work gives insight into part of the molecular mechanism of how HDAC inhibitors can affect the stability of the HDAC co-repressor complex in cardiac hypertrophy and heart failure. In addition, we demonstrated the Class IIa HDACs are required for the recruitment of the Sin3a/HDAC1/2 co-repressor complex to specific transcription factors on the target promoter.

scholarly journals RACK1 is required for adipogenesis

2016 ◽  
Vol 311 (5) ◽  
pp. C831-C836 ◽  
Author(s):  
Qinghua Kong ◽  
Lan Gao ◽  
Yanfen Niu ◽  
Pianchou Gongpan ◽  
Yuhui Xu ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Signaling Pathway ◽  
Energy Homeostasis ◽  
Adipocyte Differentiation ◽  
Metabolic Diseases ◽  
Critical Role ◽  
Adaptor Protein ◽  
Protein Levels ◽  
Ppar Γ ◽  
Intracellular Signal

Adipose tissue plays a critical role in metabolic diseases and the maintenance of energy homeostasis. RACK1 has been identified as an adaptor protein involved in multiple intracellular signal transduction pathways and diseases. However, whether it regulates adipogenesis remains unknown. Here, we reported that RACK1 is expressed in 3T3-L1 cells and murine white adipose tissue and that RACK1 knockdown by shRNA profoundly suppressed adipogenesis by reducing the expression of PPAR-γ and C/EBP-β. Depletion of RACK1 increased β-catenin protein levels and activated Wnt signaling. Furthermore, RACK1 knockdown also suppressed the PI3K-Akt-mTOR-S6K signaling pathway by reducing the PI3K p85α, pAkt T473, and S6K p70. Taken together, these results demonstrate that RACK1 is a novel factor required for adipocyte differentiation by emerging Wnt/β-catenin signaling and PI3K-Akt-mTOR-S6K signaling pathway(s).

scholarly journals Polyamines Regulate the Stability of Activating Transcription Factor-2 mRNA through RNA-binding Protein HuR in Intestinal Epithelial Cells

2007 ◽  
Vol 18 (11) ◽  
pp. 4579-4590 ◽  
Author(s):  
Lan Xiao ◽  
Jaladanki N. Rao ◽  
Tongtong Zou ◽  
Lan Liu ◽  
Bernard S. Marasa ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Rna Binding ◽  
Binding Protein ◽  
Critical Role ◽  
Rna Binding Protein ◽  
Gene Promoter ◽  
Protein Levels ◽  
Ribonucleoprotein Complexes ◽  
Activating Transcription Factor ◽  
The Stability

Maintenance of intestinal mucosal epithelial integrity requires polyamines that modulate the expression of various genes involved in cell proliferation and apoptosis. Recently, polyamines were shown to regulate the subcellular localization of the RNA-binding protein HuR, which stabilizes its target transcripts such as nucleophosmin and p53 mRNAs. The activating transcription factor-2 (ATF-2) mRNA encodes a member of the ATF/CRE-binding protein family of transcription factors and was computationally predicted to be a target of HuR. Here, we show that polyamines negatively regulate ATF-2 expression posttranscriptionally and that polyamine depletion stabilizes ATF-2 mRNA by enhancing the interaction of the 3′-untranslated region (UTR) of ATF-2 with cytoplasmic HuR. Decreasing cellular polyamines by inhibiting ornithine decarboxylase (ODC) with α-difluoromethylornithine increased the levels of ATF-2 mRNA and protein, whereas increasing polyamines by ectopic ODC overexpression repressed ATF-2 expression. Polyamine depletion did not alter transcription via the ATF-2 gene promoter but increased the stability of ATF-2 mRNA. Increased cytoplasmic HuR in polyamine-deficient cells formed ribonucleoprotein complexes with the endogenous ATF-2 mRNA and specifically bound to 3′-UTR of ATF-2 mRNA on multiple nonoverlapping 3′-UTR segments. Adenovirus-mediated HuR overexpression elevated ATF-2 mRNA and protein levels, whereas HuR silencing rendered the ATF-2 mRNA unstable and prevented increases in ATF-2 mRNA and protein. Furthermore, inhibition of ATF-2 expression prevented the increased resistance of polyamine-deficient cells to apoptosis induced by treatment with tumor necrosis factor-α and cycloheximide. These results indicate that polyamines modulate the stability of ATF-2 mRNA by altering cytoplasmic HuR levels and that polyamine-modulated ATF-2 expression plays a critical role in regulating epithelial apoptosis.

scholarly journals Identification of a region on hypoxia-inducible-factor prolyl 4-hydroxylases that determines their specificity for the oxygen degradation domains

2007 ◽  
Vol 408 (2) ◽  
pp. 231-240 ◽  
Author(s):  
Diego Villar ◽  
Alicia Vara-Vega ◽  
Manuel O. Landázuri ◽  
Luis Del Peso
Keyword(s):  
Transcription Factors ◽  
Tertiary Structure ◽  
Hypoxia Inducible Factor ◽  
Domain Swapping ◽  
Dependent Manner ◽  
Low Oxygen ◽  
Protein Levels ◽  
The Stability

HIFs [hypoxia-inducible (transcription) factors] are essential for the induction of an adaptive gene expression programme under low oxygen partial pressure. The activity of these transcription factors is mainly determined by the stability of the HIFα subunit, which is regulated, in an oxygen-dependent manner, by a family of three prolyl 4-hydroxylases [EGLN1–EGLN3 (EGL nine homologues 1–3)]. HIFα contains two, N- and C-terminal, independent ODDs (oxygen-dependent degradation domains), namely NODD and CODD, that, upon hydroxylation by the EGLNs, target HIFα for proteasomal degradation. In vitro studies indicate that each EGLN shows a differential preference for ODDs, However, the sequence determinants for such specificity are unknown. In the present study we showed that whereas EGLN1 and EGLN2 acted upon any of these ODDs to regulate HIF1α protein levels and activity in vivo, EGLN3 only acted on the CODD. With the aim of identifying the region within EGLNs responsible for their differential substrate preference, we investigated the activity and binding pattern of different EGLN deletions and chimaeric constructs generated by domain swapping between EGLN1 and EGLN3. These studies revealed a region of 97 residues that was sufficient to confer the characteristic substrate binding observed for each EGLN. Within this region, we identified the minimal sequence (EGLN1 residues 236–252) involved in substrate discrimination. Importantly, mapping of these sequences on the EGLN1 tertiary structure indicates that substrate specificity is determined by a region relatively remote from the catalytic site.

scholarly journals Isolated Erythrocytosis Associated With 3 Novel Missense Mutations in the EGLN1 Gene

2020 ◽  
Vol 8 ◽  
pp. 232470962094725
Author(s):  
Joseph A. Moore ◽  
Maimon E. Hubbi ◽  
Chenliang Wang ◽  
Yingfei Wang ◽  
Weibo Luo ◽  
...  
Keyword(s):  
Protein Stability ◽  
Cultured Cells ◽  
Hypoxia Inducible Factor ◽  
Prolyl Hydroxylase ◽  
Missense Mutations ◽  
Novel Mutations ◽  
Gene Encoding ◽  
Protein Levels ◽  
Hypoxia Inducible Factor 1 ◽  
Prolyl Hydroxylase Domain

Hypoxia-inducible factor-1 (HIF-1) is a key regulator of erythropoiesis. In this article, we report 3 novel mutations, P378S, A385T, and G206C, on the EGLN1 gene encoding the negative HIF-1α regulator prolyl hydroxylase domain-2 (PHD2) in 3 patients with isolated erythrocytosis. These mutations impair PHD2 protein stability and partially reduce PHD2 activity, leading to increased HIF-1α protein levels in cultured cells.

scholarly journals RAB37 Promotes Adipogenic Differentiation of hADSCs via the TIMP1/CD63/Integrin Signaling Pathway

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Haili Huang ◽  
Anran Li ◽  
Jin Li ◽  
Dan Sun ◽  
Ling Liang ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Early Stage ◽  
Adipogenic Differentiation ◽  
Critical Role ◽  
Proximity Ligation Assay ◽  
Integrin Β1 ◽  
Protein Levels ◽  
Proximity Ligation ◽  
Matrix Metalloproteinase 1

The adipogenic differentiation ability of human adipose-derived mesenchymal stem cells (hADSCs) is critical for the construction of tissue engineering adipose, which shows promising applications in plastic surgery and regenerative medicine. RAB37 is a member of the small RabGTPase family and plays a critical role in vesicle trafficking. However, the role of RAB37 in adipogenic differentiation of hADSCs remains unclear. Here, we report that both the mRNA and protein levels of RAB37 fluctuated during adipogenic differentiation. Upregulation of RAB37 was observed at the early stage of adipogenic differentiation, which was accompanied by increased expression of transcription factors PPARγ2 and C/EBPα, and lipoprotein lipase (LPL). Overexpression of RAB37 promoted adipogenesis of hADSCs, as revealed by Oil Red O staining and increased expression of PPARγ2, C/EBPα, and LPL. Several upregulated cytokines related to RAB37-mediated adipogenic differentiation were identified using a cytokine array, including tissue inhibitor of matrix metalloproteinase 1 (TIMP1). ELISA confirmed that upregulation of RAB37 increased the secretion of TIMP1 by hADSCs. Proximity ligation assay showed that RAB37 interacts with TIMP1 directly. Knockdown of TIMP1 compromised RAB37-mediated adipogenic differentiation. In addition, TIMP1 binds membrane receptor CD63 and integrin β1. RAB37 promotes Tyr397 phosphorylation of FAK, an important protein kinase of the integrin β1 signaling. Moreover, both knockdown of CD63 and inhibitor of FAK impeded RAB37-mediated adipogenic differentiation. In conclusion, RAB37 positively regulates adipogenic differentiation of hADSCs via the TIMP1/CD63/integrin β1 signaling pathway.

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