El complejo β-arrestina/conexina 43 (Cx43) retiene ERKS fuera del núcleo: un paso necesario para el efecto anti-apoptótico de los bisfosfonatos mediado por Cx34/ERK en osteocitos

Translated title of the contribution: β-arrestin/connexin 43 (Cx43) complex anchors ERKS outside the nucleus: A pre-requisite for bisphosphonate antiapoptotic effect mediated by Cx43/ERK in osteocytes

Lilian Plotkin, Arancha R. Gortazar, Teresita Bellido

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Bisphosphonates (BPs) anti-fracture efficacy may be due in part to inhibition of osteocyte apoptosis. This effect requires opening of connexin (Cx) 43 hemichannels and phosphorylation of the extracellular signal regulated kinases (ERKs). However, unlike ERK activation by other stimuli, the Cx43/ERK pathway activated by BPs does not result in nuclear ERK accumulation. Instead, the anti-apoptotic effect of BPs depends on phosphorylation of cytoplasmic ERK targets and is abolished by forced nuclear retention of ERKs. We now report that ERKs and the scaffolding protein β-arrestin co-immuno-precipitate with Cx43 in MLO-Y4 osteocytic cells and that the BP alendronate increases this association. Moreover, ERK2 fused to red fluorescent protein (ERK2-RFP) co-localizes with Cx43 fused to green fluorescent protein outside the nucleus in cells untreated or treated with alendronate. Alendronate does not induce ERK nuclear accumulation in cells transfected with wild type β-arrestin (wtARR) or vector control, whereas it does in cells expressing a dominant negative β-arrestin mutant (dnARR) consisting of the β-arrestin-clathrin binding domain that competes with endogenous β-arrestin for binding to clathrin. Alendronate activates ERKs in dnARRtransfected cells as effectively as in cells transfected with wtARR, demonstrating that dnARR only interferes with subcellular localization but not with activation of ERKs by BPs. Further, whereas alendronate inhibits apoptosis in cells expressing wtARR or vector control, it is ineffective in cells expressing dnARR. Thus, BPs induce the formation of a complex comprising Cx43, β-arrestin, and clathrin, which directs ERKs outside the nucleus and is indispensable for osteocyte survival induced by BPs.

Original languageSpanish
Pages (from-to)11-20
Number of pages10
JournalActualizaciones en Osteologia
Volume12
Issue number1
StatePublished - 2016

Fingerprint

Arrestin
Osteocytes
Connexin 43
Extracellular Signal-Regulated MAP Kinases
Diphosphonates
Alendronate
Clathrin
Phosphorylation
Apoptosis
Green Fluorescent Proteins
Cell Nucleus

Keywords

  • Apoptosis
  • Beta-arrestin
  • Bisphosphonate
  • Osteocyte

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Orthopedics and Sports Medicine
  • Radiology Nuclear Medicine and imaging
  • Medicine (miscellaneous)

Cite this

@article{c71e4bf81b44413eb8e889b8a784c046,
title = "El complejo β-arrestina/conexina 43 (Cx43) retiene ERKS fuera del n{\'u}cleo: un paso necesario para el efecto anti-apopt{\'o}tico de los bisfosfonatos mediado por Cx34/ERK en osteocitos",
abstract = "Bisphosphonates (BPs) anti-fracture efficacy may be due in part to inhibition of osteocyte apoptosis. This effect requires opening of connexin (Cx) 43 hemichannels and phosphorylation of the extracellular signal regulated kinases (ERKs). However, unlike ERK activation by other stimuli, the Cx43/ERK pathway activated by BPs does not result in nuclear ERK accumulation. Instead, the anti-apoptotic effect of BPs depends on phosphorylation of cytoplasmic ERK targets and is abolished by forced nuclear retention of ERKs. We now report that ERKs and the scaffolding protein β-arrestin co-immuno-precipitate with Cx43 in MLO-Y4 osteocytic cells and that the BP alendronate increases this association. Moreover, ERK2 fused to red fluorescent protein (ERK2-RFP) co-localizes with Cx43 fused to green fluorescent protein outside the nucleus in cells untreated or treated with alendronate. Alendronate does not induce ERK nuclear accumulation in cells transfected with wild type β-arrestin (wtARR) or vector control, whereas it does in cells expressing a dominant negative β-arrestin mutant (dnARR) consisting of the β-arrestin-clathrin binding domain that competes with endogenous β-arrestin for binding to clathrin. Alendronate activates ERKs in dnARRtransfected cells as effectively as in cells transfected with wtARR, demonstrating that dnARR only interferes with subcellular localization but not with activation of ERKs by BPs. Further, whereas alendronate inhibits apoptosis in cells expressing wtARR or vector control, it is ineffective in cells expressing dnARR. Thus, BPs induce the formation of a complex comprising Cx43, β-arrestin, and clathrin, which directs ERKs outside the nucleus and is indispensable for osteocyte survival induced by BPs.",
keywords = "Apoptosis, Beta-arrestin, Bisphosphonate, Osteocyte",
author = "Lilian Plotkin and Gortazar, {Arancha R.} and Teresita Bellido",
year = "2016",
language = "Spanish",
volume = "12",
pages = "11--20",
journal = "Actualizaciones en Osteologia",
issn = "1669-8975",
publisher = "Asociacion Argentina de Osteologia y Metabolismo Mineral",
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TY - JOUR

T1 - El complejo β-arrestina/conexina 43 (Cx43) retiene ERKS fuera del núcleo

T2 - un paso necesario para el efecto anti-apoptótico de los bisfosfonatos mediado por Cx34/ERK en osteocitos

AU - Plotkin, Lilian

AU - Gortazar, Arancha R.

AU - Bellido, Teresita

PY - 2016

Y1 - 2016

N2 - Bisphosphonates (BPs) anti-fracture efficacy may be due in part to inhibition of osteocyte apoptosis. This effect requires opening of connexin (Cx) 43 hemichannels and phosphorylation of the extracellular signal regulated kinases (ERKs). However, unlike ERK activation by other stimuli, the Cx43/ERK pathway activated by BPs does not result in nuclear ERK accumulation. Instead, the anti-apoptotic effect of BPs depends on phosphorylation of cytoplasmic ERK targets and is abolished by forced nuclear retention of ERKs. We now report that ERKs and the scaffolding protein β-arrestin co-immuno-precipitate with Cx43 in MLO-Y4 osteocytic cells and that the BP alendronate increases this association. Moreover, ERK2 fused to red fluorescent protein (ERK2-RFP) co-localizes with Cx43 fused to green fluorescent protein outside the nucleus in cells untreated or treated with alendronate. Alendronate does not induce ERK nuclear accumulation in cells transfected with wild type β-arrestin (wtARR) or vector control, whereas it does in cells expressing a dominant negative β-arrestin mutant (dnARR) consisting of the β-arrestin-clathrin binding domain that competes with endogenous β-arrestin for binding to clathrin. Alendronate activates ERKs in dnARRtransfected cells as effectively as in cells transfected with wtARR, demonstrating that dnARR only interferes with subcellular localization but not with activation of ERKs by BPs. Further, whereas alendronate inhibits apoptosis in cells expressing wtARR or vector control, it is ineffective in cells expressing dnARR. Thus, BPs induce the formation of a complex comprising Cx43, β-arrestin, and clathrin, which directs ERKs outside the nucleus and is indispensable for osteocyte survival induced by BPs.

AB - Bisphosphonates (BPs) anti-fracture efficacy may be due in part to inhibition of osteocyte apoptosis. This effect requires opening of connexin (Cx) 43 hemichannels and phosphorylation of the extracellular signal regulated kinases (ERKs). However, unlike ERK activation by other stimuli, the Cx43/ERK pathway activated by BPs does not result in nuclear ERK accumulation. Instead, the anti-apoptotic effect of BPs depends on phosphorylation of cytoplasmic ERK targets and is abolished by forced nuclear retention of ERKs. We now report that ERKs and the scaffolding protein β-arrestin co-immuno-precipitate with Cx43 in MLO-Y4 osteocytic cells and that the BP alendronate increases this association. Moreover, ERK2 fused to red fluorescent protein (ERK2-RFP) co-localizes with Cx43 fused to green fluorescent protein outside the nucleus in cells untreated or treated with alendronate. Alendronate does not induce ERK nuclear accumulation in cells transfected with wild type β-arrestin (wtARR) or vector control, whereas it does in cells expressing a dominant negative β-arrestin mutant (dnARR) consisting of the β-arrestin-clathrin binding domain that competes with endogenous β-arrestin for binding to clathrin. Alendronate activates ERKs in dnARRtransfected cells as effectively as in cells transfected with wtARR, demonstrating that dnARR only interferes with subcellular localization but not with activation of ERKs by BPs. Further, whereas alendronate inhibits apoptosis in cells expressing wtARR or vector control, it is ineffective in cells expressing dnARR. Thus, BPs induce the formation of a complex comprising Cx43, β-arrestin, and clathrin, which directs ERKs outside the nucleus and is indispensable for osteocyte survival induced by BPs.

KW - Apoptosis

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