title: The expression of Lamin A mutant R321X leads to endoplasmic reticulum stress with aberrant Ca2+handling.
abstract: Mutations in the Lamin A/C gene (LMNA), which encodes A-type nuclear Lamins, represent the most frequent genetic cause of dilated cardiomyopathy (DCM). This study is focused on a LMNA nonsense mutation (R321X) identified in several members of an Italian family that produces a truncated protein isoform, which co-segregates with a severe form of cardiomyopathy with poor prognosis. However, no molecular mechanisms other than nonsense mediated decay of the messenger and possible haploinsufficiency were proposed to explain DCM. Aim of this study was to gain more insights into the disease-causing mechanisms induced by the expression of R321X at cellular level. We detected the expression of R321X by Western blotting from whole lysate of a mutation carrier heart biopsy. When expressed in HEK293 cells, GFP- (or mCherry)-tagged R321X mislocalized in the endoplasmic reticulum (ER) inducing the PERK-CHOP axis of the ER stress response. Of note, confocal microscopy showed phosphorylation of PERK in sections of the mutation carrier heart biopsy. ER mislocalization of mCherry-R321X also induced impaired ER Ca2+handling, reduced capacitative Ca2+entry at the plasma membrane and abnormal nuclear Ca2+dynamics. In addition, expression of R321X by itself increased the apoptosis rate. In conclusion, R321X is the first LMNA mutant identified to date, which mislocalizes into the ER affecting cellular homeostasis mechanisms not strictly related to nuclear functions.
authors.affiliation: Department of Sciences, University of Basilicata, Potenza, Italy. monica.carmosino@unibas.it.
authors.forename: Monica
authors.initials: M
authors.lastname: Carmosino
authors.affiliation: Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, Bari, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Gerbino
authors.affiliation: Department of Sciences, University of Basilicata, Potenza, Italy.
authors.forename: Giorgia
authors.initials: G
authors.lastname: Schena
authors.affiliation: Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, Bari, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Procino
authors.affiliation: Department of Sciences, University of Basilicata, Potenza, Italy.
authors.forename: Rocchina
authors.initials: R
authors.lastname: Miglionico
authors.affiliation: Cardiology Unit, Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Forleo
authors.affiliation: Cardiology Unit, Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Favale
authors.affiliation: Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, Bari, Italy.|Consiglio Nazionale delle Ricerche, Bari, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Svelto
mesh_terms: D000328:Adult; D017209:Apoptosis; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling; D004721:Endoplasmic Reticulum / Q000378:metabolism; D059865:Endoplasmic Reticulum Stress; D005190:Family; D005260:Female; D049452:Green Fluorescent Proteins / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D007558:Italy; D034904:Lamin Type A / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D050505:Mutant Proteins / Q000378:metabolism*; D009154:Mutation / Q000235:genetics*; D010375:Pedigree; D055815:Young Adult
chemical_list: D034904:Lamin Type A; D050505:Mutant Proteins; D049452:Green Fluorescent Proteins; D002118:Calcium
keywords: Laminophaties; apoptosis; endoplasmic reticulum; nucleus; stress