The subcellular localization and activity of Drosophila cubitus interruptus are regulated at multiple levels

Development ◽  
1999 ◽  
Vol 126 (22) ◽  
pp. 5097-5106 ◽  
Author(s):  
Q.T. Wang ◽  
R.A. Holmgren
Keyword(s):  
Subcellular Localization ◽  
Nuclear Localization Signal ◽  
Transcriptional Repression ◽  
Target Genes ◽  
Cubitus Interruptus ◽  
Downstream Target ◽  
Localization Signal ◽  
Hh Signaling ◽  
Multiple Levels ◽  
Different Levels

Cubitus interruptus (Ci), a Drosophila transcription factor, mediates Hedgehog (Hh) signaling during the patterning of embryonic epidermis and larval imaginal discs. In the absence of Hh signal, Ci is cleaved to generate a truncated nuclear form capable of transcriptional repression. Hh signaling stabilizes and activates the full-length Ci protein leading to strong activation of downstream target genes including patched and decapentaplegic. A number of molecules have been implicated in the regulation of Ci. Mutations in these molecules lead to changes in Ci protein level, the extent of Ci proteolysis and the expression of Ci target genes. This paper examines the regulation of Ci subcellular localization and activity. We first characterize a bipartite nuclear localization signal (NLS) within Ci. We propose that the subcellular distribution of Ci is affected by two opposing forces, the action of the NLS and that of at least two regions targeting Ci to the cytoplasm. Further our data show that loss of PKA or Costal-2 activity does not fully mimic Hh signaling, demonstrating that Ci proteolysis and Ci activation are two distinct events which are regulated through different paths. Finally, we propose that there are three levels of apparent Ci activity, corresponding to three zones along the AP axis with different sets of gene expression and different levels of Hh signaling.

scholarly journals Emerging multifaceted roles of BAP1 complexes in biological processes

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Aileen Patricia Szczepanski ◽  
Lu Wang
Keyword(s):  
Transcriptional Repression ◽  
Target Genes ◽  
Regulatory Mechanisms ◽  
Biological Processes ◽  
Multiprotein Complex ◽  
Downstream Target ◽  
Evolutionarily Conserved ◽  
Complex Forms ◽  
Polycomb Repressive Complex 1

AbstractHistone H2AK119 mono-ubiquitination (H2AK119Ub) is a relatively abundant histone modification, mainly catalyzed by the Polycomb Repressive Complex 1 (PRC1) to regulate Polycomb-mediated transcriptional repression of downstream target genes. Consequently, H2AK119Ub can also be dynamically reversed by the BAP1 complex, an evolutionarily conserved multiprotein complex that functions as a general transcriptional activator. In previous studies, it has been reported that the BAP1 complex consists of important biological roles in development, metabolism, and cancer. However, identifying the BAP1 complex’s regulatory mechanisms remains to be elucidated due to its various complex forms and its ability to target non-histone substrates. In this review, we will summarize recent findings that have contributed to the diverse functional role of the BAP1 complex and further discuss the potential in targeting BAP1 for therapeutic use.

scholarly journals Mechanisms Directing the Nuclear Localization of the CtBP Family Proteins

2006 ◽  
Vol 26 (13) ◽  
pp. 4882-4894 ◽  
Author(s):  
Alexis Verger ◽  
Kate G. R. Quinlan ◽  
Linda A. Crofts ◽  
Stefania Spanò ◽  
Daniela Corda ◽  
...  
Keyword(s):  
Nuclear Localization ◽  
Nuclear Import ◽  
Nuclear Localization Signal ◽  
Transcriptional Repression ◽  
Intracellular Trafficking ◽  
Nuclear Accumulation ◽  
Splice Isoforms ◽  
Localization Signal ◽  
Splice Isoform ◽  
Partner Proteins

ABSTRACT The C-terminal binding protein (CtBP) family includes four proteins (CtBP1 [CtBP1-L], CtBP3/BARS [CtBP1-S], CtBP2, and RIBEYE) which are implicated both in transcriptional repression and in intracellular trafficking. However, the precise mechanisms by which different CtBP proteins are targeted to different subcellular regions remains unknown. Here, we report that the nuclear import of the various CtBP proteins and splice isoforms is differentially regulated. We show that CtBP2 contains a unique nuclear localization signal (NLS) located within its N-terminal region, which contributes to its nuclear accumulation. Using heterokaryon assays, we show that CtBP2 is capable of shuttling between the nucleus and cytoplasm of the cell. Moreover, CtBP2 can heterodimerize with CtBP1-L and CtBP1-S and direct them to the nucleus. This effect strongly depends on the CtBP2 NLS. PXDLS motif-containing transcription factors, such as BKLF, that bind CtBP proteins can also direct them to the nucleus. We also report the identification of a splice isoform of CtBP2, CtBP2-S, that lacks the N-terminal NLS and localizes to the cytoplasm. Finally, we show that mutation of the CtBP NADH binding site impairs the ability of the proteins to dimerize and to associate with BKLF. This reduces the nuclear accumulation of CtBP1. Our results suggest a model in which the nuclear localization of CtBP proteins is influenced by the CtBP2 NLS, by binding to PXDLS motif partner proteins, and through the effect of NADH on CtBP dimerization.

scholarly journals GLI transcriptional repression is inert prior to Hedgehog pathway activation

2021 ◽  
Author(s):  
Rachel K. Lex ◽  
Weiqiang Zhou ◽  
Zhicheng Ji ◽  
Kristin N. Falkenstein ◽  
Kaleigh E. Schuler ◽  
...  
Keyword(s):  
Transcriptional Repression ◽  
Limb Development ◽  
Target Genes ◽  
Hedgehog Pathway ◽  
Transcriptional Repressors ◽  
Posterior Limb ◽  
Gli Proteins ◽  
Pathway Activation ◽  
Hh Signaling ◽  
Anterior Posterior

In the absence of Hedgehog (HH) signaling, GLI proteins are post-translationally modified within cilia into transcriptional repressors that subsequently prevent sub-threshold activation of HH target genes. GLI repression is presumably important for preventing precocious expression of target genes before the onset of HH pathway activation, a presumption that underlies the pre-patterning model of anterior-posterior limb polarity. Here, we report that GLI3 repressor is abundant and binds to target genes in early limb development. However, contrary to expectations, GLI3 repression neither regulates the activity of GLI enhancers nor expression of HH target genes as it does after HH signaling has been established. Within the cilia, the transition to active GLI repression is accompanied by increases in axonemal GLI3 localization, possibly signifying altered GLI3 processing. Together, our results demonstrate that GLI3 repression does not prevent precocious activation of HH target genes, or have a pre-patterning role in regulating anterior-posterior limb polarity.

scholarly journals PHLPP1 Counter-regulates STAT1-mediated Inflammatory Signaling

2019 ◽  
Author(s):  
Ksenya Cohen-Katsenelson ◽  
Joshua D. Stender ◽  
Agnieszka T. Kawashima ◽  
Gema Lordén ◽  
Satoshi Uchiyama ◽  
...  
Keyword(s):  
Innate Immunity ◽  
Nuclear Localization ◽  
Nuclear Localization Signal ◽  
Target Genes ◽  
Cytokine Signaling ◽  
List Type ◽  
Ph Domain ◽  
Inflammatory Signaling ◽  
Lps Challenge ◽  
Localization Signal

ABSTRACTInflammation is an essential aspect of innate immunity but also contributes to diverse human diseases. Although much is known about the kinases that control inflammatory signaling, less is known about the opposing phosphatases. Here we report that deletion of the gene encoding PH domain Leucine-rich repeat Protein Phosphatase 1 (PHLPP1) protects mice from lethal lipopolysaccharide (LPS) challenge and liveEscherichia coliinfection. Investigation of PHLPP1 function in macrophages reveals that it controls the magnitude and duration of inflammatory signaling by dephosphorylating the transcription factor STAT1 on Ser727 to inhibit its activity, reduce its promoter residency, and reduce the expression of target genes involved in innate immunity and cytokine signaling. This previously undescribed function of PHLPP1 depends on a bipartite nuclear localization signal in its unique N-terminal extension. Our data support a model in which nuclear PHLPP1 dephosphorylates STAT1 to control the magnitude and duration of inflammatory signaling in macrophages.HIGHLIGHTSPHLPP1 controls the transcription of genes involved in inflammatory signalingPHLPP1 dephosphorylates STAT1 on Ser727 to reduce its transcriptional activityPHLPP1 has a nuclear localization signal and a nuclear exclusion signalLoss of PHLPP1 protects mice from sepsis-induced death

scholarly journals Identification and analysis of KLF13 variants in patients with congenital heart disease

2019 ◽  
Author(s):  
Wenjuan Li ◽  
Baolei Li ◽  
Tingting Li ◽  
Ergeng Zhang ◽  
Qingjie Wang ◽  
...  
Keyword(s):  
Congenital Heart Disease ◽  
Transcription Factor ◽  
Heart Disease ◽  
Subcellular Localization ◽  
Protein Expression ◽  
Heart Development ◽  
Congenital Heart ◽  
Target Genes ◽  
Healthy Controls ◽  
Downstream Target

Abstract Background: The protein Kruppel-like factor 13 (KLF13) is a member of the KLF family that has been identified as a novel cardiac transcription factor which is involved in heart development. However, the relationship between KLF13 variants and CHDs in humans remains largely unknown. The present study aimed to screen the KLF13 variants in CHDs patients and genetically analyze the function of these variants. Methods: KLF13 variants were sequenced in a cohort of 309 CHD patients and population-matched healthy controls (n = 200) using targeted sequencing. To investigate the effect of variants on the functional ability of the KLF13 protein, the expressions and subcellular localization of protein, as well as the transcriptional activities of downstream genes and physically interacted with other transcription factor were assessed. Results: Two novel heterozygous variants, c.487C>T (P163S) and c.467G>A (S156N), were identified in two out of 309 CHDs patients with Tricuspid-valve atresia and transposition of the great arteries, respectively. No variants were found among healthy controls. The variant c.467G>A (S156N) increased protein expression and enhanced functionality compared with that of wild-type, without affecting the subcellular localization. The other variant, c.487C>T (P163S), did not show any abnormalities in protein expression and subcellular localization, however it eliminated the transcriptional activities of downstream target genes and physically interacted with TBX5, another cardiac transcription factor. Conclusion: Our results show that the S156N and P163S variants contributed to CHD etiology. Additionally, our findings suggest that KLF13 may be a potential gene contributing to congenital heart disease.

scholarly journals Identification of a putative nuclear localization signal in maspin protein shed light into its nuclear import regulation

2018 ◽  
Author(s):  
Jeffrey Reina ◽  
Lixin Zhou ◽  
Marcos R.M. Fontes ◽  
Nelly Panté ◽  
Nathalie Cella
Keyword(s):  
Subcellular Localization ◽  
Nuclear Localization ◽  
Hela Cells ◽  
Nuclear Import ◽  
Nuclear Localization Signal ◽  
Molecular Mechanisms ◽  
Nuclear Translocation ◽  
Biological Activities ◽  
Dependent Manner ◽  
Localization Signal

AbstractMaspin (SERPINB5) is a potential tumor suppressor gene with pleiotropic biological activities, including regulation of cell proliferation, death, adhesion, migration and gene expression. Several studies suggest that subcellular localization plays an essential role on maspin tumor suppression activity. In this study we investigated the molecular mechanisms underlying maspin nucleocytoplasmic shuttling. Anin vitronuclear-import assay using digitonin-permeabilized HeLa cells demonstrated that maspin enters the nucleus by an energy-and carrier-independent mechanism. However, previous studies indicated that maspin subcellular localization is regulated in the cell. Using a nuclear localization signal (NLS) prediction software, we identified a putative NLS in the maspin amino acid sequence. To distinguish between passive and regulated nuclear translocation, maspinNLS or the full-length protein (MaspinFL) were fused to 5GFP, rendering the construct too large to enter the nucleus passively. Unexpectedly, 5GFP-maspinNLS, but not maspinFL-5GFP, entered the nucleus of HeLa cells. Dominant-negative Ran-GTPase mutants RanQ69L or RanT24N, suppressed 5GFP-maspinNLS nuclear localization. In summary, we provide evidence that maspin translocates to the nucleus passively. In addition, we identified a peptide in the maspin protein sequence, which is able to drive a 5GFP construct to the nucleus in an energy-dependent manner.

Linkage of the potent leukemogenic activity of Meis1 to cell-cycle entry and transcriptional regulation of cyclin D3

Blood ◽  
2010 ◽  
Vol 115 (20) ◽  
pp. 4071-4082 ◽  
Author(s):  
Bob Argiropoulos ◽  
Eric Yung ◽  
Ping Xiang ◽  
Chao Yu Lo ◽  
Florian Kuchenbauer ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Transcriptional Activation ◽  
Transcriptional Repression ◽  
Target Genes ◽  
Hox Genes ◽  
Cell Cycle Control ◽  
Cyclin D3 ◽  
Leukemic Cells ◽  
Downstream Target

MEIS1 is a three–amino acid loop extension class homeodomain-containing homeobox (HOX) cofactor that plays key roles in normal hematopoiesis and leukemogenesis. Expression of Meis1 is rate-limiting in MLL-associated leukemias and potently interacts with Hox and NUP98-HOX genes in leukemic transformation to promote self-renewal and proliferation of hematopoietic progenitors. The oncogenicity of MEIS1 has been linked to its transcriptional activation properties. To further reveal the pathways triggered by Meis1, we assessed the function of a novel engineered fusion form of Meis1, M33-MEIS1, designed to confer transcriptional repression to Meis1 target genes that are otherwise up-regulated in normal and malignant hematopoiesis. Retroviral overexpression of M33-Meis1 resulted in the rapid and complete eradication of M33-Meis1–transduced normal and leukemic cells in vivo. Cell-cycle analysis showed that M33-Meis1 impeded the progression of cells from G1-to-S phase, which correlated with significant reduction of cyclin D3 levels and the inhibition of retinoblastoma (pRb) hyperphosphorylation. We identified cyclin D3 as a direct downstream target of MEIS1 and M33-MEIS1 and showed that the G1-phase accumulation and growth suppression induced by M33-Meis1 was partially relieved by overexpression of cyclin D3. This study provides strong evidence linking the growth-promoting activities of Meis1 to the cyclin D-pRb cell-cycle control pathway.

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