The endoplasmic reticulum remains functionally connected by vesicular transport after its fragmentation in cells expressing Z-α1-antitrypsin.
α1-Antitrypsin is a serine protease inhibitor produced in the liver that is responsible for the regulation of pulmonary inflammation. The commonest pathogenic gene mutation yields Z-α1-antitrypsin, which has a propensity to self-associate forming polymers that become trapped in inclusions of endoplasmic reticulum (ER). It is unclear whether these inclusions are connected to the main ER network in Z-α1-antitrypsin-expressing cells. Using live cell imaging, we found that despite inclusions containing an immobile matrix of polymeric α1-antitrypsin, small ER resident proteins can diffuse freely within them. Inclusions have many features to suggest they represent fragmented ER, and some are physically separated from the tubular ER network, yet we observed cargo to be transported between them in a cytosol-dependent fashion that is sensitive to N-ethylmaleimide and dependent on Sar1 and sec22B. We conclude that protein recycling occurs between ER inclusions despite their physical separation.-Dickens, J. A., Ordóñez, A., Chambers, J. E., Beckett, A. J., Patel, V., Malzer, E., Dominicus, C. S., Bradley, J., Peden, A. A., Prior, I. A., Lomas, D. A., Marciniak, S. J. The endoplasmic reticulum remains functionally connected by vesicular transport after its fragmentation in cells expressing Z-α1-antitrypsin.
Cambridge Institute for Medical Research, Cambridge, United Kingdom.|Department of Medicine, University of Cambridge, Cambridge, United Kingdom.
Jennifer A
JA
Dickens
Cambridge Institute for Medical Research, Cambridge, United Kingdom.
Adriana
A
Ordóñez
Cambridge Institute for Medical Research, Cambridge, United Kingdom.|Department of Medicine, University of Cambridge, Cambridge, United Kingdom.
Joseph E
JE
Chambers
Department of Biomedical Science, University of Sheffield, Sheffield, United Kingdom.
Alison J
AJ
Beckett
Cambridge Institute for Medical Research, Cambridge, United Kingdom.
Vruti
V
Patel
Cambridge Institute for Medical Research, Cambridge, United Kingdom.
Elke
E
Malzer
Cambridge Institute for Medical Research, Cambridge, United Kingdom.
Caia S
CS
Dominicus
Cambridge Institute for Medical Research, Cambridge, United Kingdom.
Jayson
J
Bradley
Department of Biomedical Science, University of Sheffield, Sheffield, United Kingdom.
Andrew A
AA
Peden
Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom; and.
Ian A
IA
Prior
UCL Respiratory, University College London, London, United Kingdom.
David A
DA
Lomas
Cambridge Institute for Medical Research, Cambridge, United Kingdom; sjm20@cam.ac.uk.|Department of Medicine, University of Cambridge, Cambridge, United Kingdom.
Stefan J
SJ
Marciniak
D000818:Animals; D001692:Biological Transport / Q000235:genetics / Q000502:physiology*; D016466:CHO Cells; D002478:Cells, Cultured; D003412:Cricetulus; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D000515:alpha 1-Antitrypsin / Q000235:genetics / Q000378:metabolism*
D000515:alpha 1-Antitrypsin
ER stress; SNARE; homotypic fusion; serpin