The connexin43-interacting protein, CIP85, mediates the internalization of connexin43 from the plasma membrane

Cochrane, Kimberly; Su, Vivian; Lau, Alan F.

doi:10.3109/15419061.2013.784745

Cited by 16 publications

(18 citation statements)

References 98 publications

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“…Additionally, the loss of dynamin GTPase activity or the reduction of dynamin2, clathrin, AP-2, or Dab2 proteins inhibited the internalization of Cx43, as observed by a significant decrease in the number of annular junctions. The Cx43-interacting protein of 85 kDa, CIP85, is a Rab GTPase-activating protein that was found to co-localize with Cx43 at the plasma membrane (54,55). In our experiments, where cells undergo acute turnover and connexin degradation by pharmacological stimulation of PKC, lysosomal degradation is followed by proteasomal degradation.…”

Section: Discussionmentioning

confidence: 82%

Protein Kinase Cδ-mediated Phosphorylation of Connexin43 Gap Junction Channels Causes Movement within Gap Junctions followed by Vesicle Internalization and Protein Degradation

Cone

Cavin

Ambrosi

et al. 2014

Journal of Biological Chemistry

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Background: Connexin43, a ubiquitous gap junction protein, is phosphorylated by protein kinase C on serine 368. Results: After PKC␦ activation, phospho-Ser-368 Connexin43 channels segregated into the gap junction center and were subsequently internalized and degraded. Conclusion: PKC␦ phosphorylation triggered internalization and degradation of Connexin43 channels without dephosphorylation. Significance: Differential phosphorylation events are used to sort and traffic Connexin43 channels within gap junctions and into the cytoplasm.

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Section: Discussionmentioning

confidence: 82%

Protein Kinase Cδ-mediated Phosphorylation of Connexin43 Gap Junction Channels Causes Movement within Gap Junctions followed by Vesicle Internalization and Protein Degradation

Cone

Cavin

Ambrosi

et al. 2014

Journal of Biological Chemistry

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“…The NMR solution structure of WW3 has already been solved albeit in complex with a small peptide (46). All 1 H, 15 N, and 13 C backbone resonances and most side chain and aromatic groups of the WW1 and WW2 domains (97 and 95% of the expected resonances, respectively) were assigned in 1ϫ PBS (pH 7.4) at 25°C (Fig. 1C).…”

Section: Structural Characterization Of the Nedd4 Ww Domains-mentioning

confidence: 99%

“…B, CD spectra of each Nedd4 WW domain in the far UV in 1ϫ PBS (pH 7.5). C, 15 N HSQC spectra of each Nedd4 WW domain in 1ϫ PBS (pH 7.5). Each amide cross-peak is labeled.…”

Section: Structural Characterization Of the Nedd4 Ww Domains-mentioning

confidence: 99%

“…The rat Nedd4 WW domains WW1 (Nedd4 245-281 ), WW2 (Nedd4 401-437 ), and WW3 (Nedd4 458 -494 ) were cloned into the bacterial expression vector pGEX-KT (GST-tagged; Amersham Biosciences) using standard PCR methods and transformed for overexpression in BL21(DE3) cells (unlabeled, 15 N-, or 13 C, 15 N-labeled) (Agilent Technologies). Purification was conducted as described previously for a recombinant GSTtagged protein with the tag being removed by thrombin digestion (32)(33)(34).…”

Section: Expression and Purification Of Recombinant Proteins And Peptmentioning

confidence: 99%

“…Consequently, removal from the plasma membrane is directionally regulated as internalization of the channels within one of the coupled cells forms a double membrane macrostructure called an annular gap junction or connexosome (10); clathrin and other endocytic adaptors have been shown to be involved in this process (11)(12)(13)(14). Degradation of connexins involves both the lysosomal (endosome or autophagy) and proteasomal pathways (15)(16)(17). Implicated in the regulation of these processes are post-translational modifications (18).…”

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confidence: 99%

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Structural Studies of the Nedd4 WW Domains and Their Selectivity for the Connexin43 (Cx43) Carboxyl Terminus

Spagnol

Kieken

Kopanic

et al. 2016

Journal of Biological Chemistry

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Neuronal precursor cell-expressed developmentally downregulated 4 (Nedd4) was the first ubiquitin protein ligase identified to interact with connexin43 (Cx43), and its suppressed expression results in accumulation of gap junction plaques at the plasma membrane. Nedd4-mediated ubiquitination of Cx43 is required to recruit Eps15 and target Cx43 to the endocytic pathway. Although the Cx43 residues that undergo ubiquitination are still unknown, in this study we address other unresolved questions pertaining to the molecular mechanisms mediating the direct interaction between Nedd4 (WW1-3 domains) and Cx43 (carboxyl terminus (CT) 279 to interact with the back face of ␤-strand 3 (Tyr 286 is on the front face) and loop 2, forming a horseshoe-shaped arrangement. The close sequence identity of WW2 with WW1 and WW3 residues that interact with the Cx43CT PPXY motif and Ser(P) 279 /Ser(P) 282 strongly suggests that the significantly lower binding affinity of WW1 is the result of a more rigid structure. This study presents the first structure illustrating how phosphorylation of the Cx43CT domain helps mediate the interaction with a molecular partner involved in gap junction regulation.Gap junction channels serve to directly interconnect the cytoplasm of neighboring cells, allowing the passage of ions, metabolites, and signaling molecules. Gap junction intercellular communication is an important process that mediates electrical impulse propagation, regulation of cell growth, and whole organ development. Gap junction channels are formed by the apposition of connexons from adjacent cells where each connexon is formed by six connexin proteins. Connexins share a similar topology of four transmembrane domains, two extracellular loops, and three cytoplasmic domains (N terminus, cytoplasmic loop, and C terminus (CT) 3 ). Of the 21 human connexins, connexin43 (Cx43) is the most completely characterized isoform in terms of channel gating properties (1), identified phosphorylation sites (2), known protein partners (3), connexon assembly (4), and channel degradation (5-7).Unlike most membrane proteins, connexins exhibit exceptionally high turnover rates with half-lives ranging from 1.5 to 5 h (8). The initial step leading to degradation, internalization from the plasma membrane, is a complex process because docked connexons are unable to be separated under physiological conditions (9). Consequently, removal from the plasma membrane is directionally regulated as internalization of the channels within one of the coupled cells forms a double membrane macrostructure called an annular gap junction or connexosome (10); clathrin and other endocytic adaptors have been shown to be involved in this process (11)(12)(13)(14). Degradation of connexins involves both the lysosomal (endosome or autophagy) and proteasomal pathways (15)(16)(17). Implicated in the regulation of these processes are post-translational modifications (18). For example, studies using cultured cells have shown that activation of protein kinase C (PKC) or mitogenactivated prote...

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The connexin 43 C-terminus: A tail of many tales

Leithe

Mesnil

Aasen

2018

Biochimica et Biophysica Acta (BBA) - Biomembranes

180

197

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Connexins are chordate gap junction channel proteins that, by enabling direct communication between the cytosols of adjacent cells, create a unique cell signalling network. Gap junctional intercellular communication (GJIC) has important roles in controlling cell growth and differentiation and in tissue development and homeostasis. Moreover, several non-canonical connexin functions unrelated to GJIC have been discovered. Of the 21 members of the human connexin family, connexin 43 (Cx43) is the most widely expressed and studied. The long cytosolic C-terminus (CT) of Cx43 is subject to extensive post-translational modifications that modulate its intracellular trafficking and gap junction channel gating. Moreover, the Cx43 CT contains multiple domains involved in protein interactions that permit crosstalk between Cx43 and cytoskeletal and regulatory proteins. These domains endow Cx43 with the capacity to affect cell growth and differentiation independently of GJIC. Here, we review the current understanding of the regulation and unique functions of the Cx43 CT, both as an essential component of full-length Cx43 and as an independent signalling hub. We highlight the complex regulatory and signalling networks controlled by the Cx43 CT, including the extensive protein interactome that underlies both gap junction channel-dependent and -independent functions. We discuss these data in relation to the recent discovery of the direct translation of specific truncated forms of Cx43. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.

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The connexin43-interacting protein, CIP85, mediates the internalization of connexin43 from the plasma membrane

Cited by 16 publications

References 98 publications

Protein Kinase Cδ-mediated Phosphorylation of Connexin43 Gap Junction Channels Causes Movement within Gap Junctions followed by Vesicle Internalization and Protein Degradation

Protein Kinase Cδ-mediated Phosphorylation of Connexin43 Gap Junction Channels Causes Movement within Gap Junctions followed by Vesicle Internalization and Protein Degradation

Structural Studies of the Nedd4 WW Domains and Their Selectivity for the Connexin43 (Cx43) Carboxyl Terminus

The connexin 43 C-terminus: A tail of many tales

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