Long-term Potentiation of Wound-induced Exocytosis and Plasma Membrane Repair Is Dependant on cAMP-response Element-mediated Transcription via a Protein Kinase C- and p38 MAPK-dependent Pathway

Tatsuru Togo

doi:10.1074/jbc.m406327200

Abstract

Ca(2+)-regulated exocytosis is required for rapid resealing of disrupted plasma membranes. It has been previously demonstrated that repeated membrane disruptions reseal more quickly than the initial wound and that this facilitated response requires the transcription factor cAMP-response element-binding protein (CREB). This study examines the signaling pathway between membrane disruption and CREB-dependent gene expression in 3T3 fibroblasts. A reporter gene assay using pCRE-d2EGFP revealed that membrane disruption induced CRE-mediated transcription. Immunofluorescence observations suggested that membrane disruption activated CREB, p38 mitogen-activated protein kinase (p38 MAPK), and MAPK kinase3/6, the kinase responsible for activation of p38 MAPK. CREB phosphorylation upon membrane disruption was inhibited by a specific p38 MAPK inhibitor, SB203580. Both CRE-mediated transcription and long-term potentiation of membrane resealing and wound-induced exocytosis were suppressed when cells were wounded in the presence of either SB203580 or Go-6976, a specific protein kinase C (PKC) inhibitor. Furthermore, activation of MAPK kinase3/6 was impaired by PKC inhibition during membrane disruption. These results suggest that PKC mediates the stimulation of CREB-dependent gene expression through a p38 MAPK pathway upon membrane disruption.

Highlights

Mechanical stress induces disruptions of plasma membranes in many animal tissues under physiological conditions, and a cell survives these disruptions by rapidly resealing its cell membrane [1]
Cell Membrane Disruption Induces cAMP-response element (CRE)-mediated Transcription in 3T3 Fibroblasts—In a previous study, it was demonstrated that repeated cell membrane disruptions reseal more quickly than the initial wound and that this long-term potentiation of membrane resealing requires a transcription factor, cAMP-response element-binding protein (CREB) [15]
It has been previously demonstrated that repeated membrane disruption reveals long-term potentiation of Ca2ϩ-regulated exocytosis in 3T3 fibroblasts, which is closely correlated with faster membrane resealing rates at repeated wounds [15]

Summary

Introduction

Mechanical stress induces disruptions of plasma membranes in many animal tissues under physiological conditions, and a cell survives these disruptions by rapidly resealing its cell membrane [1]. Expression of genes having a cAMP-response element (CRE) can be activated through a variety of signaling cascades that include protein kinase A (PKA), CaMK, and mitogen-activated protein kinase (MAPK) pathways These pathways are reported to be involved in complex and diverse processes such as learning, memory, synaptic plasticity, development, and stress responses [11,12,13,14]. Membrane disruption was found to induce CREB phosphorylation and CRE-mediated transcription via a PKC- and p38 MAPK-dependent pathway This signaling pathway was required for long-term potentiation of membrane resealing and wound-induced exocytosis

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