scholarly journals Cx50 requires an intact PDZ-binding motif and ZO-1 for the formation of functional intercellular channels

2011 ◽  
Vol 22 (23) ◽  
pp. 4503-4512 ◽  
Author(s):  
Zhifang Chai ◽  
Daniel A. Goodenough ◽  
David L. Paul
Keyword(s):  
Gap Junction ◽  
Hela Cells ◽  
Pdz Domain ◽  
Cell Communication ◽  
Normal Function ◽  
Scaffolding Protein ◽  
Binding Motif ◽  
Interacting Protein ◽  
And Function

The three connexins expressed in the ocular lens each contain PDZ domain–binding motifs directing a physical association with the scaffolding protein ZO-1, but the significance of the interaction is unknown. We found that Cx50 with PDZ-binding motif mutations did not form gap junction plaques or induce cell–cell communication in HeLa cells, whereas the addition of a seven–amino acid PDZ-binding motif restored normal function to Cx50 lacking its entire C-terminal cytoplasmic domain. C-Terminal deletion had a similar although weaker effect on Cx46 but little if any effect on targeting and function of Cx43. Furthermore, small interfering RNA knockdown of ZO-1 completely inhibited the formation of gap junctions by wild-type Cx50 in HeLa cells. Thus both a PDZ-binding motif and ZO-1 are necessary for Cx50 intercellular channel formation in HeLa cells. Knock-in mice expressing Cx50 with a PDZ-binding motif mutation phenocopied Cx50 knockouts. Furthermore, differentiating lens fibers in the knock-in displayed extensive intracellular Cx50, whereas plaques in mature fibers contained only Cx46. Thus normal Cx50 function in vivo also requires an intact PDZ domain–binding motif. This is the first demonstration of a connexin-specific requirement for a connexin-interacting protein in gap junction assembly.

scholarly journals The function and dynamics of the apical scaffolding protein E3KARP are regulated by cell-cycle phosphorylation

2015 ◽  
Vol 26 (20) ◽  
pp. 3615-3627 ◽  
Author(s):  
Cécile Sauvanet ◽  
Damien Garbett ◽  
Anthony Bretscher
Keyword(s):  
Pdz Domain ◽  
Duplication Event ◽  
Scaffolding Protein ◽  
Gene Duplication Event ◽  
Pdz Domains ◽  
Tail Region ◽  
Dynamics And Function ◽  
And Function

We examine the dynamics and function of the apical scaffolding protein E3KARP/NHERF2, which consists of two PDZ domains and a tail containing an ezrin-binding domain. The exchange rate of E3KARP is greatly enhanced during mitosis due to phosphorylation at Ser-303 in its tail region. Whereas E3KARP can substitute for the function of the closely related scaffolding protein EBP50/NHERF1 in the formation of interphase microvilli, E3KARP S303D cannot. Moreover, the S303D mutation enhances the in vivo dynamics of the E3KARP tail alone, whereas in vitro the interaction of E3KARP with active ezrin is unaffected by S303D, implicating another factor regulating dynamics in vivo. A-Raf is found to be required for S303 phosphorylation in mitotic cells. Regulation of the dynamics of EBP50 is known to be dependent on its tail region but modulated by PDZ domain occupancy, which is not the case for E3KARP. Of interest, in both cases, the mechanisms regulating dynamics involve the tails, which are the most diverged region of the paralogues and probably evolved independently after a gene duplication event that occurred early in vertebrate evolution.

scholarly journals C. elegans germ granules require both assembly and localized regulators for mRNA repression

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Scott Takeo Aoki ◽  
Tina R. Lynch ◽  
Sarah L. Crittenden ◽  
Craig A. Bingman ◽  
Marvin Wickens ◽  
...  
Keyword(s):  
Liquid Droplet ◽  
Scaffolding Protein ◽  
P Granules ◽  
C Elegans ◽  
Cytoplasmic Rna ◽  
And Function ◽  
Rnp Granules ◽  
Key Residues ◽  
Reporter Mrna

AbstractCytoplasmic RNA–protein (RNP) granules have diverse biophysical properties, from liquid to solid, and play enigmatic roles in RNA metabolism. Nematode P granules are paradigmatic liquid droplet granules and central to germ cell development. Here we analyze a key P granule scaffolding protein, PGL-1, to investigate the functional relationship between P granule assembly and function. Using a protein–RNA tethering assay, we find that reporter mRNA expression is repressed when recruited to PGL-1. We determine the crystal structure of the PGL-1 N-terminal region to 1.5 Å, discover its dimerization, and identify key residues at the dimer interface. Mutations of those interface residues prevent P granule assembly in vivo, de-repress PGL-1 tethered mRNA, and reduce fertility. Therefore, PGL-1 dimerization lies at the heart of both P granule assembly and function. Finally, we identify the P granule-associated Argonaute WAGO-1 as crucial for repression of PGL-1 tethered mRNA. We conclude that P granule function requires both assembly and localized regulators.

Abstract 37: Nrip Deficiency Leads to Dilated Cardiomyopathy

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Show-Li Chen
Keyword(s):  
Calcium Transient ◽  
Receptor Interaction ◽  
Cell Width ◽  
Interacting Protein ◽  
Cardiac Tissues ◽  
Calmodulin Binding ◽  
Calcineurin Phosphatase ◽  
And Function

Previously, we demonstrate a gene, nuclear receptor interaction protein (NRIP, also named DCAF6 or IQWD1) as a Ca2+- dependent calmodulin binding protein that can activate calcineurin phosphatase activity. Here, we found that α-actinin-2 (ACTN2), is one of NRIP-interacting proteins from the yeast two-hybrid system using NRIP as a prey. We further confirmed the direct bound between NRIP and ACTN2 using in vitro protein-protein interaction and in vivo co-immunoprecipitation assays. To further map the binding domain of each protein, the results showed the IQ domain of NRIP responsible for ACTN2 binding, and EF hand motif of ACTN2 responsible for NRIP bound. Due to ACTN2 is a biomarker of muscular Z-disc complex; we found the co-localization of NRIP and ACTN2 in cardiac tissues by immunofluorescence assays. Taken together, NRIP is a novel ACTN2-interacting protein. To investigate insights into in vivo function of NRIP, we generated conventional NRIP-null mice. The H&E staining results are shown in the hearts of NRIP KO mice are enlarged and dilated and the cell width of NRIP KO cardiomyocyte is increased. The EM of NRIP KO heart muscles reveal the reduction of I-band width and extension length of Z-disc in sarcomere structure; and the echocardiography shows the diminished fractional shortening in heart functions. Additionally, the calcium transient and sarcomere contraction length in cardiomyocytes of NRIP KO is weaker and shorter than wt; respectively. In conclusion, NRIP is a novel Z-disc protein and has function for maintenance of sarcomere integrity structure and function for calcium transient and muscle contraction.

scholarly journals Anisotropic Cardiac Conduction

2020 ◽  
Vol 9 (4) ◽  
pp. 202-210
Author(s):  
Irum Kotadia ◽  
John Whitaker ◽  
Caroline Roney ◽  
Steven Niederer ◽  
Mark O’Neill ◽  
...  
Keyword(s):  
Gap Junction ◽  
Cardiac Tissue ◽  
Diffusion Tensor ◽  
Interstitial Fibrosis ◽  
Cardiac Conduction ◽  
Principal Mechanism ◽  
Disease States ◽  
And Function ◽  
Anisotropic Conduction

Anisotropy is the property of directional dependence. In cardiac tissue, conduction velocity is anisotropic and its orientation is determined by myocyte direction. Cell shape and size, excitability, myocardial fibrosis, gap junction distribution and function are all considered to contribute to anisotropic conduction. In disease states, anisotropic conduction may be enhanced, and is implicated, in the genesis of pathological arrhythmias. The principal mechanism responsible for enhanced anisotropy in disease remains uncertain. Possible contributors include changes in cellular excitability, changes in gap junction distribution or function and cellular uncoupling through interstitial fibrosis. It has recently been demonstrated that myocyte orientation may be identified using diffusion tensor magnetic resonance imaging in explanted hearts, and multisite pacing protocols have been proposed to estimate myocyte orientation and anisotropic conduction in vivo. These tools have the potential to contribute to the understanding of the role of myocyte disarray and anisotropic conduction in arrhythmic states.

scholarly journals Zinc Modulation of Hemi-Gap-Junction Channel Currents in Retinal Horizontal Cells

2009 ◽  
Vol 101 (4) ◽  
pp. 1774-1780 ◽  
Author(s):  
Ziyi Sun ◽  
Dao-Qi Zhang ◽  
Douglas G. McMahon
Keyword(s):  
Gap Junction ◽  
Inhibitory Action ◽  
Divalent Cations ◽  
Horizontal Cells ◽  
Visual Signals ◽  
Histidine Residues ◽  
Gap Junction Channel ◽  
And Function ◽  
Channel Currents

Hemi-gap-junction (HGJ) channels of retinal horizontal cells (HCs) function as transmembrane ion channels that are modulated by voltage and calcium. As an endogenous retinal neuromodulator, zinc, which is coreleased with glutamate at photoreceptor synapses, plays an important role in shaping visual signals by acting on postsynaptic HCs in vivo. To understand more fully the regulation and function of HC HGJ channels, we examined the effect of Zn2+ on HGJ channel currents in bass retinal HCs. Hemichannel currents elicited by depolarization in Ca2+-free medium and in 1 mM Ca2+ medium were significantly inhibited by extracellular Zn2+. The inhibition by Zn2+ of hemichannel currents was dose dependent with a half-maximum inhibitory concentration of 37 μM. Compared with other divalent cations, Zn2+ exhibited higher inhibitory potency, with the order being Zn2+ > Cd2+ ≈ Co2+ > Ca2+ > Ba2+ > Mg2+. Zn2+ and Ca2+ were found to modulate HGJ channels independently in additivity experiments. Modification of histidine residues with N-bromosuccinimide suppressed the inhibitory action of Zn2+, whereas modification of cysteine residues had no significant effect on Zn2+ inhibition. Taken together, these results suggest that zinc acts on HGJ channels in a calcium-independent way and that histidine residues on the extracellular domain of HGJ channels mediate the inhibitory action of zinc.

scholarly journals Slitrk2 controls excitatory synapse development via PDZ-mediated protein interactions

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Kyung Ah Han ◽  
Jinhu Kim ◽  
Hyeonho Kim ◽  
Dongwook Kim ◽  
Dongseok Lim ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Intracellular Signaling ◽  
Hippocampal Neurons ◽  
Pdz Domain ◽  
Protein Tyrosine Phosphatases ◽  
Excitatory Synapse ◽  
Receptor Protein ◽  
Binding Motif ◽  
Synapse Development

AbstractMembers of the Slitrk (Slit- and Trk-like protein) family of synaptic cell-adhesion molecules control excitatory and inhibitory synapse development through isoform-dependent extracellular interactions with leukocyte common antigen-related receptor protein tyrosine phosphatases (LAR-RPTPs). However, how Slitrks participate in activation of intracellular signaling pathways in postsynaptic neurons remains largely unknown. Here we report that, among the six members of the Slitrk family, only Slitrk2 directly interacts with the PDZ domain-containing excitatory scaffolds, PSD-95 and Shank3. The interaction of Slitrk2 with PDZ proteins is mediated by the cytoplasmic COOH-terminal PDZ domain-binding motif (Ile-Ser-Glu-Leu), which is not found in other Slitrks. Mapping analyses further revealed that a single PDZ domain of Shank3 is responsible for binding to Slitrk2. Slitrk2 forms in vivo complexes with membrane-associated guanylate kinase (MAGUK) family proteins in addition to PSD-95 and Shank3. Intriguingly, in addition to its role in synaptic targeting in cultured hippocampal neurons, the PDZ domain-binding motif of Slitrk2 is required for Slitrk2 promotion of excitatory synapse formation, transmission, and spine development in the CA1 hippocampal region. Collectively, our data suggest a new molecular mechanism for conferring isoform-specific regulatory actions of the Slitrk family in orchestrating intracellular signal transduction pathways in postsynaptic neurons.

scholarly journals In Vivo Ablation of the Conserved GATA-Binding Motif in the Amh Promoter Impairs Amh Expression in the Male Mouse

Endocrinology ◽  
2019 ◽  
Vol 160 (4) ◽  
pp. 817-826 ◽  
Author(s):  
Marie France Bouchard ◽  
Francis Bergeron ◽  
Jasmine Grenier Delaney ◽  
Louis-Mathieu Harvey ◽  
Robert S Viger
Keyword(s):  
Developmental Time ◽  
Gonadal Development ◽  
Conclusive Evidence ◽  
Binding Motif ◽  
Male Embryo ◽  
Steroidogenic Factor 1 ◽  
Protein Levels ◽  
Positive Modulator ◽  
And Function

Abstract GATA4 is an essential transcriptional regulator required for gonadal development, differentiation, and function. In the developing testis, proposed GATA4-regulated genes include steroidogenic factor 1 (Nr5a1), SRY-related HMG box 9 (Sox9), and anti-Müllerian hormone (Amh). Although some of these genes have been validated as genuine GATA4 targets, it remains unclear whether GATA4 is a direct regulator of endogenous Amh transcription. We used a CRISPR/Cas9-based approach to specifically inactivate or delete the sole GATA-binding motif of the proximal mouse Amh promoter. AMH mRNA and protein levels were assessed at developmental time points corresponding to elevated AMH levels: fetal and neonate testes in males and adult ovaries in females. In males, loss of GATA binding to the Amh promoter significantly reduced Amh expression. Although the loss of GATA binding did not block the initiation of Amh transcription, AMH mRNA and protein levels failed to upregulate in the developing fetal and neonate testis. Interestingly, adult male mice presented no anatomical anomalies and had no evidence of retained Müllerian duct structures, suggesting that AMH levels, although markedly reduced, were sufficient to masculinize the male embryo. In contrast to males, GATA binding to the Amh promoter was dispensable for Amh expression in the adult ovary. These results provide conclusive evidence that in males, GATA4 is a positive modulator of Amh expression that works in concert with other key transcription factors to ensure that the Amh gene is sufficiently expressed in a correct spatiotemporal manner during fetal and prepubertal testis development.

scholarly journals Gap junction internalization and processing in vivo: a 3D immuno-electron microscopy study

2020 ◽  
pp. jcs.252726
Author(s):  
Rachael P. Norris ◽  
Mark Terasaki
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Connexin 43 ◽  
New Technology ◽  
Cell Communication ◽  
Membrane Vesicles ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Annular Gap

Gap junctions have well-established roles in cell-cell communication by way of forming permeable intercellular channels. Less is understood about their internalization, which forms double membrane vesicles containing cytosol and membranes from another cell, called connexosomes or annular gap junctions. Here, we systematically investigated the fate of connexosomes in intact ovarian follicles. High pressure frozen, serial sectioned tissue was immunogold labeled for Connexin 43. Within a volume corresponding to ∼35 cells, every labeled structure was categorized and its surface area was measured. Measurements support the concept that multiple connexosomes form from larger invaginated gap junctions. Subsequently, the inner and outer membranes separate, Cx43 immunogenicity is lost from the outer membrane, and the inner membrane appears to undergo fission. One pathway for processing involves lysosomes, based on localization of Cathespin B to some processed connexosomes. In summary, this study demonstrates new technology for high-resolution analyses of gap junction processing.

scholarly journals Tissue engineering in urology

2013 ◽  
Vol 3 (5) ◽  
pp. 403 ◽  
Author(s):  
Derek J. Matoka ◽  
Earl Y. Cheng
Keyword(s):  
Tissue Engineering ◽  
Multidisciplinary Approach ◽  
Normal Function ◽  
Healthy Tissue ◽  
Clinical Applicability ◽  
Basic Technology ◽  
And Function

Tissue engineering encompasses a multidisciplinary approach gearedtoward the development of biological substitutes designed to restoreand maintain normal function in diseased or injured tissues. Thisarticle reviews the basic technology that is used to generateimplantable tissue-engineered grafts in vitro that will exhibit characteristicsin vivo consistent with the physiology and function ofthe equivalent healthy tissue. We also examine the current trendsin tissue engineering designed to tailor scaffold construction, promoteangiogenesis and identify an optimal seeded cell source.Finally, we describe several currently applied therapeutic modalitiesthat use a tissue-engineered construct. While notable progresshas clearly been demonstrated in this emerging field, these effortshave not yet translated into widespread clinical applicability. Withcontinued development and innovation, there is optimism that thetremendous potential of this field will be realized.L’ingénierie tissulaire englobe une approche multidisciplinaireaxée sur le développement de substituts biologiques en vue derétablir et de maintenir la fonction normale de tissus lésés. L’articlequi suit passe en revue la technologie fondamentale utilisée pourgénérer des greffons implantables produits par ingénierie in vitroet possédant des caractéristiques in vivo correspondant aux tissussains équivalents sur les plans physiologique et fonctionnel.Nous examinons également les tendances actuelles en ingénierietissulaire visant à adapter des échafaudages tissulaires, à promouvoirl’angiogenèse et à dégager une source optimale de cellulesimplantables. Enfin, nous décrivons plusieurs modalités thérapeutiquesactuellement mises en application utilisant un échafaudagecréé par ingénierie tissulaire. En dépit de progrès remarquablesdans ce domaine en effervescence, les efforts déployés ne se sontpas encore traduits par une applicabilité clinique étendue. Desdéveloppements et des percées continus permettent d’être optimisteface au potentiel prodigieux de ce domaine.

scholarly journals Structure and function of human Vps20 and Snf7 proteins

2004 ◽  
Vol 377 (3) ◽  
pp. 693-700 ◽  
Author(s):  
Jeremy W. PECK ◽  
Emma T. BOWDEN ◽  
Peter D. BURBELO
Keyword(s):  
Protein Interactions ◽  
Osmotic Shock ◽  
Multivesicular Body ◽  
Protein Protein Interactions ◽  
Interacting Protein ◽  
Endosomal Membrane ◽  
Genomic Studies ◽  
Vacuolar Protein ◽  
And Function

Snf7p (sucrose non-fermenting) and Vps20p (vacuolar protein-sorting) are small coil-coiled proteins involved in yeast MVB (multivesicular body) structure, formation and function. In the present study, we report the identification of three human homologues of yeast Snf7p, designated hSnf7-1, hSnf7-2 and hSnf7-3, and a single human Vps20p homologue, designated hVps20, that may have similar roles in humans. Immunofluorescence studies showed that hSnf7-1 and hSnf7-3 localized in large vesicular structures that also co-localized with late endosomal/lysosomal structures induced by overexpressing an ATPase-defective Vps4-A mutant. In contrast, overexpressed hVps20 showed a typical endosomal membrane-staining pattern, and co-expression of hVps20 with Snf7-1 dispersed the large Snf7-staining vesicles. Interestingly, overexpression of both hSnf7 and hVps20 proteins induced a post-endosomal defect in cholesterol sorting. To explore possible protein–protein interactions involving hSnf7 proteins, we used information from yeast genomic studies showing that yeast Snf7p can interact with proteins involved in MVB function. Using a glutathione S-transferase-capture approach with several mammalian homologues of such yeast Snf7p-interacting proteins, we found that all three hSnf7s interacted with mouse AIP1 [ALG-2 (apoptosis-linked gene 2) interacting protein 1], a mammalian Bro1p [BCK1 (bypass of C kinase)-like resistance to osmotic shock]-containing protein involved in cellular vacuolization and apoptosis. Whereas mapping experiments showed that the N-terminus of AIP1 containing both a Bro1 and an α-helical domain were required for interaction with hSnf7-1, Snf7-1 did not interact with another human Bro1-containing molecule, rhophilin-2. Co-immunoprecipitation experiments confirmed the in vivo interaction of hSnf7-1 and AIP1. Additional immunofluorescence experiments showed that hSnf7-1 recruited cytosolic AIP1 to the Snf7-induced vacuolar-like structures. Together these results suggest that mammalian Vps20, AIP1 and Snf7 proteins, like their yeast counterparts, play roles in MVB function.

Sign in / Sign up

Export Citation Format

Share Document