PMID- 29538751
OWN - NLM
STAT- MEDLINE
DCOM- 20190214
LR  - 20210109
IS  - 1460-2083 (Electronic)
IS  - 0964-6906 (Linking)
VI  - 27
IP  - 10
DP  - 2018 May 15
TI  - Heteropolymerization of alpha-1-antitrypsin mutants in cell models mimicking 
      heterozygosity.
PG  - 1785-1793
LID - 10.1093/hmg/ddy090 [doi]
AB  - The most common genotype associated with severe alpha-1-antitrypsin deficiency (AATD) 
      is the Z homozygote. The Z variant (Glu342Lys) of alpha-1-antitrypsin (AAT) undergoes 
      a conformational change and is retained within the endoplasmic reticulum (ER) of 
      hepatocytes leading to the formation of ordered polymeric chains and inclusion 
      bodies. Accumulation of mutated protein predisposes to cirrhosis whilst plasma 
      AAT deficiency leads to emphysema. Increased risk of liver and lung disease has 
      also been reported in heterozygous subjects who carry Z in association with the 
      milder S allele (Glu264Val) or even with wild-type M. However, it is unknown 
      whether Z AAT can co-polymerize with other AAT variants in vivo. We co-expressed 
      two AAT variants, each modified by a different tag, in cell models that replicate 
      AAT deficiency. We used pull-down assays to investigate interactions between 
      co-expressed variants and showed that Z AAT forms heteropolymers with S and with 
      the rare Mmalton (Phe52del) and Mwurzburg (Pro369Ser) mutants, and to a lesser 
      extent with the wild-type protein. Heteropolymers were recognized by the 2C1 mAb 
      that binds to Z polymers in vivo. There was increased intracellular accumulation 
      of AAT variants when co-expressed with Z AAT, suggesting a dominant negative 
      effect of the Z allele. The molecular interactions between S and Z AAT were 
      confirmed by confocal microscopy showing their colocalization within dilated ER 
      cisternae and by positivity in Proximity Ligation Assays. These results provide 
      the first evidence of intracellular co-polymerization of AAT mutants and 
      contribute to understanding the risk of liver disease in SZ and MZ heterozygotes.
FAU - Laffranchi, Mattia
AU  - Laffranchi M
AD  - Department of Molecular and Translational Medicine, University of Brescia, 25123 
      Brescia, Italy.
FAU - Berardelli, Romina
AU  - Berardelli R
AD  - Department of Molecular and Translational Medicine, University of Brescia, 25123 
      Brescia, Italy.
FAU - Ronzoni, Riccardo
AU  - Ronzoni R
AD  - Department of Molecular and Translational Medicine, University of Brescia, 25123 
      Brescia, Italy.
AD  - UCL Respiratory and the Institute of Structural and Molecular Biology, University 
      College London, London WC1E 6BT, UK.
FAU - Lomas, David A
AU  - Lomas DA
AD  - UCL Respiratory and the Institute of Structural and Molecular Biology, University 
      College London, London WC1E 6BT, UK.
FAU - Fra, Annamaria
AU  - Fra A
AD  - Department of Molecular and Translational Medicine, University of Brescia, 25123 
      Brescia, Italy.
LA  - eng
GR  - MR/N024842/1/MRC_/Medical Research Council/United Kingdom
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - England
TA  - Hum Mol Genet
JT  - Human molecular genetics
JID - 9208958
RN  - 0 (Protein Aggregates)
RN  - 0 (alpha 1-Antitrypsin)
SB  - IM
MH  - Alleles
MH  - Emphysema/blood/complications/*genetics/physiopathology
MH  - Endoplasmic Reticulum/genetics/pathology
MH  - Gene Expression Regulation/genetics
MH  - Genotype
MH  - HEK293 Cells
MH  - Hepatocytes/metabolism/pathology
MH  - Heterozygote
MH  - Humans
MH  - Liver
MH  - Liver Cirrhosis/complications/*genetics/physiopathology
MH  - Protein Aggregates/genetics
MH  - Protein Conformation
MH  - Protein Multimerization/genetics
MH  - alpha 1-Antitrypsin/blood/chemistry/*genetics
MH  - alpha 1-Antitrypsin Deficiency/complications/*genetics/physiopathology
EDAT- 2018/03/15 06:00
MHDA- 2019/02/15 06:00
CRDT- 2018/03/15 06:00
PHST- 2018/01/31 00:00 [received]
PHST- 2018/03/08 00:00 [accepted]
PHST- 2018/03/15 06:00 [pubmed]
PHST- 2019/02/15 06:00 [medline]
PHST- 2018/03/15 06:00 [entrez]
AID - 4925789 [pii]
AID - 10.1093/hmg/ddy090 [doi]
PST - ppublish
SO  - Hum Mol Genet. 2018 May 15;27(10):1785-1793. doi: 10.1093/hmg/ddy090.