Pin1 Facilitates the Phosphorylation-Dependent Ubiquitination of SF-1 To Regulate Gonadotropin β-Subunit Gene Transcription

ABSTRACT Pin1 is a peptidyl-prolyl cis-trans isomerase which catalyzes the isomerization of phosphorylated Ser/Thr-Pro peptide bonds. Pin1 knockout mice have marked abnormalities in their reproductive development and function. However, the molecular mechanisms underlying their reproductive defects are poorly understood. Herein, we demonstrate that Pin1 is required for both basal and GnRH-induced gonadotropin β-subunit gene transcription, through interactions with the transcription factors SF-1, Pitx1, and Egr-1. Pin1 activates transcription of the gonadotropin β-subunit genes synergistically with these transcription factors, either by modulating their stability or by increasing their protein-protein interactions. Notably, we provide evidence that Pin1 is required for the Ser203 phosphorylation-dependent ubiquitination of SF-1, which facilitates SF-1-Pitx1 interactions and therefore results in an enhancement of SF-1 transcriptional activity. Furthermore, we demonstrate that in gonadotrope cells, sufficient levels of activated Pin1 are maintained through transcriptional and posttranslational regulation by GnRH-induced signaling cascades. Our results suggest that Pin1 functions as a novel player in GnRH-induced signal pathways and is involved in gonadotropin β-subunit gene transcription by modulating the activity of various specific transcription factors.

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Distinct activities of Scrib module proteins organize epithelial polarity

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1918462117 ◽

2020 ◽

Vol 117 (21) ◽

pp. 11531-11540 ◽

Cited By ~ 2

Author(s):

Mark J. Khoury ◽

David Bilder

Keyword(s):

Protein Interactions ◽

Molecular Mechanisms ◽

Epithelial Polarity ◽

Protein Protein Interactions ◽

Kinase C ◽

Mutual Antagonism ◽

Discs Large ◽

Lethal Giant Larvae ◽

Epithelial Structure ◽

And Function

A polarized architecture is central to both epithelial structure and function. In many cells, polarity involves mutual antagonism between the Par complex and the Scribble (Scrib) module. While molecular mechanisms underlying Par-mediated apical determination are well-understood, how Scrib module proteins specify the basolateral domain remains unknown. Here, we demonstrate dependent and independent activities of Scrib, Discs-large (Dlg), and Lethal giant larvae (Lgl) using theDrosophilafollicle epithelium. Our data support a linear hierarchy for localization, but rule out previously proposed protein–protein interactions as essential for polarization. Cortical recruitment of Scrib does not require palmitoylation or polar phospholipid binding but instead an independent cortically stabilizing activity of Dlg. Scrib and Dlg do not directly antagonize atypical protein kinase C (aPKC), but may instead restrict aPKC localization by enabling the aPKC-inhibiting activity of Lgl. Importantly, while Scrib, Dlg, and Lgl are each required, all three together are not sufficient to antagonize the Par complex. Our data demonstrate previously unappreciated diversity of function within the Scrib module and begin to define the elusive molecular functions of Scrib and Dlg.

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Analysis of high-resolution 3D intrachromosomal interactions aided by Bayesian network modeling

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1620425114 ◽

2017 ◽

Vol 114 (48) ◽

pp. E10359-E10368 ◽

Cited By ~ 8

Author(s):

Xizhe Zhang ◽

Sergio Branciamore ◽

Grigoriy Gogoshin ◽

Andrei S. Rodin ◽

Arthur D. Riggs

Keyword(s):

Transcription Factors ◽

Bayesian Network ◽

Protein Interactions ◽

High Intensity ◽

B Lymphocyte ◽

Protein Protein Interactions ◽

Transcription Start Sites ◽

Pairwise Interactions ◽

Binding Factor ◽

And Function

Long-range intrachromosomal interactions play an important role in 3D chromosome structure and function, but our understanding of how various factors contribute to the strength of these interactions remains poor. In this study we used a recently developed analysis framework for Bayesian network (BN) modeling to analyze publicly available datasets for intrachromosomal interactions. We investigated how 106 variables affect the pairwise interactions of over 10 million 5-kb DNA segments in the B-lymphocyte cell line GB12878. Strictly data-driven BN modeling indicates that the strength of intrachromosomal interactions (hic_strength) is directly influenced by only four types of factors: distance between segments, Rad21 or SMC3 (cohesin components),transcription at transcription start sites (TSS), and the number of CCCTC-binding factor (CTCF)–cohesin complexes between the interacting DNA segments. Subsequent studies confirmed that most high-intensity interactions have a CTCF–cohesin complex in at least one of the interacting segments. However, 46% have CTCF on only one side, and 32% are without CTCF. As expected, high-intensity interactions are strongly dependent on the orientation of the ctcf motif, and, moreover, we find that the interaction between enhancers and promoters is similarly dependent on ctcf motif orientation. Dependency relationships between transcription factors were also revealed, including known lineage-determining B-cell transcription factors (e.g., Ebf1) as well as potential novel relationships. Thus, BN analysis of large intrachromosomal interaction datasets is a useful tool for gaining insight into DNA–DNA, protein–DNA, and protein–protein interactions.

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Distinct activities of Scrib module proteins organize epithelial polarity

10.1101/866863 ◽

2019 ◽

Author(s):

Mark J. Khoury ◽

David Bilder

Keyword(s):

Protein Interactions ◽

Molecular Mechanisms ◽

Epithelial Polarity ◽

Protein Protein Interactions ◽

Membrane Recruitment ◽

Mutual Antagonism ◽

Stem Cell Divisions ◽

Epithelial Structure ◽

And Function ◽

Rule Out

ABSTRACTA polarized architecture is central to both epithelial structure and function. In many cells, polarity involves mutual antagonism between the Par complex and the Scrib module. While molecular mechanisms underlying Par-mediated apical determination are well-understood, how Scrib module proteins specify the basolateral domain remains unknown. Here, we demonstrate dependent and independent activities of Scrib, Dlg and Lgl using the Drosophila follicle epithelium. Our data support a linear hierarchy for localization, but rule out previously proposed protein-protein interactions as essential for polarization. Membrane recruitment of Scrib does not require palmitoylation or polar phospholipid binding but instead an independent cortically-stabilizing activity of Dlg. Scrib and Dlg do not directly antagonize aPKC, but may instead restrict aPKC localization by enabling the aPKC-inhibiting activity of Lgl. Importantly, while Scrib, Dlg and Lgl are each required, all three together are not sufficient to antagonize the Par complex. Our data demonstrate previously unappreciated diversity of function within the Scrib module and begin to define the elusive molecular functions of Scrib and Dlg.SIGNIFICANCE STATEMENTTo enable their physiological functions, cells must polarize their plasma membrane. In many epithelia, polarity is regulated by balanced activity of the apical Par complex and basolateral Scribble module. While the former is understood in molecular detail, little is known about how the latter works. We identify distinct functions of the three Scribble module proteins, separating independent roles in a localization hierarchy from cooperative roles in apical polarity antagonism and showing that they are not together sufficient to specify basolateral identity. This work establishes an essential basis for a mechanistic understanding of this core polarity machinery that controls processes ranging from stem cell divisions to organ morphogenesis across animal species.

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The Functions of BET Proteins in Gene Transcription of Biology and Diseases

Frontiers in Molecular Biosciences ◽

10.3389/fmolb.2021.728777 ◽

2021 ◽

Vol 8 ◽

Author(s):

Ka Lung Cheung ◽

Claudia Kim ◽

Ming-Ming Zhou

Keyword(s):

Transcription Factors ◽

Rna Polymerase Ii ◽

Gene Transcription ◽

Protein Interactions ◽

Therapeutic Strategy ◽

Regulation Of Gene Expression ◽

Transcriptional Elongation ◽

Protein Protein Interactions ◽

Inflammatory Disorders ◽

Damage Repair

The BET (bromodomain and extra-terminal domain) family proteins, consisting of BRD2, BRD3, BRD4, and testis-specific BRDT, are widely acknowledged as major transcriptional regulators in biology. They are characterized by two tandem bromodomains (BDs) that bind to lysine-acetylated histones and transcription factors, recruit transcription factors and coactivators to target gene sites, and activate RNA polymerase II machinery for transcriptional elongation. Pharmacological inhibition of BET proteins with BD inhibitors has been shown as a promising therapeutic strategy for the treatment of many human diseases including cancer and inflammatory disorders. The recent advances in bromodomain protein biology have further uncovered the complex and versatile functions of BET proteins in the regulation of gene expression in chromatin. In this review article, we highlight our current understanding of BET proteins’ functions in mediating protein–protein interactions required for chromatin-templated gene transcription and splicing, chromatin remodeling, DNA replication, and DNA damage repair. We further discuss context-dependent activator vs. repressor functions of individual BET proteins, isoforms, and bromodomains that may be harnessed for future development of BET bromodomain inhibitors as emerging epigenetic therapies for cancer and inflammatory disorders.

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Structure, Function, Involvement in Diseases and Targeting of 14-3-3 Proteins: An Update

Current Medicinal Chemistry ◽

10.2174/0929867324666170426095015 ◽

2018 ◽

Vol 25 (1) ◽

pp. 5-21 ◽

Cited By ~ 25

Author(s):

Ylenia Cau ◽

Daniela Valensin ◽

Mattia Mori ◽

Sara Draghi ◽

Maurizio Botta

Keyword(s):

Protein Interactions ◽

Molecular Mechanisms ◽

Physiological Role ◽

Specific Protein ◽

Protein Protein Interactions ◽

Cellular Processes ◽

Protein Partners ◽

High Sequence Homology ◽

Small Molecule Modulators

14-3-3 is a class of proteins able to interact with a multitude of targets by establishing protein-protein interactions (PPIs). They are usually found in all eukaryotes with a conserved secondary structure and high sequence homology among species. 14-3-3 proteins are involved in many physiological and pathological cellular processes either by triggering or interfering with the activity of specific protein partners. In the last years, the scientific community has collected many evidences on the role played by seven human 14-3-3 isoforms in cancer or neurodegenerative diseases. Indeed, these proteins regulate the molecular mechanisms associated to these diseases by interacting with (i) oncogenic and (ii) pro-apoptotic proteins and (iii) with proteins involved in Parkinson and Alzheimer diseases. The discovery of small molecule modulators of 14-3-3 PPIs could facilitate complete understanding of the physiological role of these proteins, and might offer valuable therapeutic approaches for these critical pathological states.

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Transactivation Functions of the N-Terminal Domains of Nuclear Hormone Receptors: Protein Folding and Coactivator Interactions

Molecular Endocrinology ◽

10.1210/me.2002-0258 ◽

2003 ◽

Vol 17 (1) ◽

pp. 1-10 ◽

Cited By ~ 125

Author(s):

Raj Kumar ◽

E. Brad Thompson

Keyword(s):

Dna Binding ◽

Protein Interactions ◽

Hormone Receptors ◽

Nuclear Hormone Receptor ◽

Binding Domain ◽

Dna Binding Domain ◽

Protein Protein Interactions ◽

Carboxy Terminal ◽

And Function ◽

Terminal Domains

Abstract The N-terminal domains (NTDs) of many members of the nuclear hormone receptor (NHR) family contain potent transcription-activating functions (AFs). Knowledge of the mechanisms of action of the NTD AFs has lagged, compared with that concerning other important domains of the NHRs. In part, this is because the NTD AFs appear to be unfolded when expressed as recombinant proteins. Recent studies have begun to shed light on the structure and function of the NTD AFs. Recombinant NTD AFs can be made to fold by application of certain osmolytes or when expressed in conjunction with a DNA-binding domain by binding that DNA-binding domain to a DNA response element. The sequence of the DNA binding site may affect the functional state of the AFs domain. If properly folded, NTD AFs can bind certain cofactors and primary transcription factors. Through these, and/or by direct interactions, the NTD AFs may interact with the AF2 domain in the ligand binding, carboxy-terminal portion of the NHRs. We propose models for the folding of the NTD AFs and their protein-protein interactions.

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Quantitative analysis of the interactions between HIV-1 integrase and retroviral reverse transcriptases

Biochemical Journal ◽

10.1042/bj20071279 ◽

2008 ◽

Vol 412 (1) ◽

pp. 163-170 ◽

Cited By ~ 21

Author(s):

Alon Herschhorn ◽

Iris Oz-Gleenberg ◽

Amnon Hizi

Keyword(s):

Conformational Changes ◽

Protein Interactions ◽

Molecular Mechanisms ◽

Reaction Model ◽

Protein Protein Interactions ◽

Common Site ◽

Leukaemia Virus ◽

Reverse Transcriptases ◽

Interaction Kinetics ◽

Hiv 1

The RT (reverse transcriptase) of HIV-1 interacts with HIV-1 IN (integrase) and inhibits its enzymatic activities. However, the molecular mechanisms underling these interactions are not well understood. In order to study these mechanisms, we have analysed the interactions of HIV-1 IN with HIV-1 RT and with two other related RTs: those of HIV-2 and MLV (murine-leukaemia virus). All three RTs inhibited HIV-1 IN, albeit to a different extent, suggesting a common site of binding that could be slightly modified for each one of the studied RTs. Using surface plasmon resonance technology, which monitors direct protein–protein interactions, we performed kinetic analyses of the binding of HIV-1 IN to these three RTs and observed interesting binding patterns. The interaction of HIV-1 RT with HIV-1 IN was unique and followed a two-state reaction model. According to this model, the initial IN–RT complex formation was followed by a conformational change in the complex that led to an elevation of the total affinity between these two proteins. In contrast, HIV-2 and MLV RTs interacted with IN in a simple bi-molecular manner, without any apparent secondary conformational changes. Interestingly, HIV-1 and HIV-2 RTs were the most efficient inhibitors of HIV-1 IN activity, whereas HIV-1 and MLV RTs showed the highest affinity towards HIV-1 IN. These modes of direct protein interactions, along with the apparent rate constants calculated and the correlations of the interaction kinetics with the capacity of the RTs to inhibit IN activities, are all discussed.

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Thyroid Hormone Regulation of Thyrotropin α- and β-Subunit Gene Transcription

DNA ◽

10.1089/dna.1985.4.301 ◽

1985 ◽

Vol 4 (4) ◽

pp. 301-307 ◽

Cited By ~ 26

Author(s):

JAMES A. GURR ◽

IONE A. KOURIDES

Keyword(s):

Thyroid Hormone ◽

Gene Transcription ◽

Hormone Regulation ◽

Β Subunit ◽

Subunit Gene

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Significance of thiol-disulfide balance in SARS-CoV-2 infection

Medicinski podmladak ◽

10.5937/mp72-32874 ◽

2021 ◽

Vol 72 (3) ◽

pp. 30-36

Author(s):

Tatjana Simić

Keyword(s):

Cell Surface ◽

Host Cell ◽

Protein Interactions ◽

Viral Entry ◽

Molecular Mechanisms ◽

Alkylating Agents ◽

Protein S ◽

Protein Protein Interactions ◽

Virus Surface ◽

Host Cell Surface

Studies of the molecular mechanisms regarding interaction of different viruses with receptors on the host cell surface have shown that the viral entry depends on the specific relationship between free thiol (SH) groups and disulfides on the virus surface, as well as the thiol disulfide balance on the host cell surface. The presence of oxidizing compounds or alkylating agents, which disturb the thiol-disulfide balance on the surface of the virus, can also affect its infectious potential. Disturbed thiol-disulfide balance may also influence protein-protein interactions between SARS-CoV-2 protein S and ACE2 receptors of the host cell. This review presents the basic mechanisms of maintaining intracellular and extracellular thiol disulfide balance and previous experimental and clinical evidence in favor of impaired balance in SARS-CoV-2 infection. Besides, the results of the clinical application or experimental analysis of compounds that induce changes in the thiol disulfide balance towards reduction of disulfide bridges in proteins of interest in COVID-19 infection are presented.

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β-Subunit overexpression alters the stoicheometry of assembled Na-K-ATPase subunits in MDCK cells

AJP Renal Physiology ◽

10.1152/ajprenal.90406.2008 ◽

2008 ◽

Vol 295 (5) ◽

pp. F1314-F1323 ◽

Cited By ~ 12

Author(s):

Rebecca J. Clifford ◽

Jack H. Kaplan

Keyword(s):

Protein Interactions ◽

Mdck Cells ◽

Β Subunit ◽

Protein Protein Interactions ◽

Cellular Mechanisms ◽

Atpase Subunit ◽

Subunit Expression ◽

Atpase Subunits ◽

Confocal Images ◽

The Individual

In eukaryotic cells, the apparent maintenance of 1:1 stoicheometry between the Na-K-ATPase α- and β-subunits led us to question whether this was alterable and thus if some form of regulation was involved. We have examined the consequences of overexpressing Na-K-ATPase β1-subunits using Madin-Darby canine kidney (MDCK) cells expressing flag-tagged β1-subunits (β1flag) or Myc-tagged β1-subunits (β1myc) under the control of a tetracycline-dependent promoter. The induction of β1flag subunit synthesis in MDCK cells, which increases β1-subunit expression at the plasma membrane by more than twofold, while maintaining stable α1 expression levels, revealed that all mature β1-subunits associate with α1-subunits, and no evidence of “free” β1-subunits was obtained. Consequently, the ratio of assembled β1- to α1-subunits is significantly increased when “extra” β-subunits are expressed. An increased β1/α1 stoicheometry is also observed in cells treated with tunicamycin, suggesting that the protein-protein interactions involved in these complexes are not dependent on glycosylation. Confocal images of cocultured β1myc-expressing and β1flag-expressing MDCK cells show colocalization of β1myc and β1flag subunits at the lateral membranes of neighboring cells, suggesting the occurrence of intercellular interactions between the β-subunits. Immunoprecipitation using MDCK cells constitutively expressing β1myc and tetracycline-regulated β1flag subunits confirmed β-β-subunit interactions. These results demonstrate that the equimolar ratio of assembled β1/α1-subunits of the Na-K-ATPase in kidney cells is not fixed by the inherent properties of the interacting subunits. It is likely that cellular mechanisms are present that regulate the individual Na-K-ATPase subunit abundance.

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