Saltatory formation, sliding and dissolution of ER–PM junctions in migrating cancer cells

Hayley Dingsdale,Muhammad Awais,Emmanuel Okeke,Robert Sutton,Lee Haynes,David N Criddle,Alexei V Tepikin

doi:10.1042/bj20121864

Hayley Dingsdale, Muhammad Awais + Show 5 more

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https://doi.org/10.1042/bj20121864

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Journal: Biochemical Journal	Publication Date: Mar 14, 2013
Citations: 14	License type: CC BY 3.0

Affiliation: University of Liverpool

Abstract

We demonstrated three novel forms of dynamic behaviour of junctions between the ER (endoplasmic reticulum) and the PM (plasma membrane) in migrating cancer cells: saltatory formation, long-distance sliding and dissolution. The individual ER–PM junctions formed near the leading edge of migrating cells (usually within 0.5 μm of polymerized actin and close to focal adhesions) and appeared suddenly without sliding from the interior of the cell. The long distance sliding and dissolution of ER–PM junctions accompanied the tail withdrawal.

Highlights

The recent discovery of the mechanism of store-operated Ca2 + entry (SOCE) propelled the junctions between the endoplasmic reticulum (ER) and the plasma membrane (PM) into the limelight of the cell signalling research field
SOCE is initiated by a decrease in the Ca2+ concentration in the ER ([Ca2+ ]ER) [2]; the decrease is detected by stromal interaction molecule (STIM) proteins, which form oligomers, translocate to ER–PM junctions and activate Ca2 + release-activated Ca2 + channel protein (Orai) (Ca2+ releaseactivated Ca2+ channel protein) channels in the PM [3,4,5,6,7]
yellow fluorescent protein (YFP)–STIM1 and mCherry–Orai1 [both with a CMV promoter] were described previously [21]; as expected YFP– STIM1 translocates to puncta and co-clusters with mCherry–Orai1 in cells treated with cyclopiazonic acid (CPA)

Summary

INTRODUCTION

The recent discovery of the mechanism of SOCE (store-operated Ca2+ entry) propelled the junctions between the ER (endoplasmic reticulum) and the PM (plasma membrane) into the limelight of the cell signalling research field (reviewed in [1]). Direct contact between STIM (transmembrane proteins in the ER) and Orai (transmembrane proteins in the PM) proteins is necessary to activate SOCE channels [5,7]. This is only possible in structures where the ER membrane and PM are very close to one another, i.e. in ER–PM junctions. The distance between the membranes in such junctions is less than 25 nm [8,9,10,11] and ribosomes are excluded [8,11] Previous studies reported both stationary ER–PM junctions [8] and junctions which rapidly form as a result of the translocation of ER strands towards the PM [10]. We decided to characterize the localization and dynamics of the ER– PM junctions in migrating cancer cells

MATERIALS AND METHODS

Dingsdale and others

RESULTS AND DISCUSSION