TY - JOUR
T1 - Mice harbouring a SCA28 patient mutation in AFG3L2 develop late-onset ataxia associated with enhanced mitochondrial proteotoxicity
AU - Mancini, Cecilia
AU - Hoxha, Eriola
AU - Iommarini, Luisa
AU - Brussino, Alessandro
AU - Richter, Uwe
AU - Montarolo, Francesca
AU - Cagnoli, Claudia
AU - Parolisi, Roberta
AU - Gondor Morosini, Diana Iulia
AU - Nicolò, Valentina
AU - Maltecca, Francesca
AU - Muratori, Luisa
AU - Ronchi, Giulia
AU - Geuna, Stefano
AU - Arnaboldi, Francesca
AU - Donetti, Elena
AU - Giorgio, Elisa
AU - Cavalieri, Simona
AU - Di Gregorio, Eleonora
AU - Pozzi, Elisa
AU - Ferrero, Marta
AU - Riberi, Evelise
AU - Casari, Giorgio
AU - Altruda, Fiorella
AU - Turco, Emilia
AU - Gasparre, Giuseppe
AU - Battersby, Brendan J.
AU - Porcelli, Anna Maria
AU - Ferrero, Enza
AU - Brusco, Alfredo
AU - Tempia, Filippo
PY - 2019/4
Y1 - 2019/4
N2 - Spinocerebellar ataxia 28 is an autosomal dominant neurodegenerative disorder caused by missense mutations affecting the proteolytic domain of AFG3L2, a major component of the mitochondrial m-AAA protease. However, little is known of the underlying pathogenetic mechanisms or how to treat patients with SCA28. Currently available Afg3l2 mutant mice harbour deletions that lead to severe, early-onset neurological phenotypes that do not faithfully reproduce the late-onset and slowly progressing SCA28 phenotype. Here we describe production and detailed analysis of a new knock-in murine model harbouring an Afg3l2 allele carrying the p.Met665Arg patient-derived mutation. Heterozygous mutant mice developed normally but adult mice showed signs of cerebellar ataxia detectable by beam test. Although cerebellar pathology was negative, electrophysiological analysis showed a trend towards increased spontaneous firing in Purkinje cells from heterozygous mutants with respect to wild-type controls. As homozygous mutants died perinatally with evidence of cardiac atrophy, for each genotype we generated mouse embryonic fibroblasts (MEFs) to investigate mitochondrial function. MEFs from mutant mice showed altered mitochondrial bioenergetics, with decreased basal oxygen consumption rate, ATP synthesis and mitochondrial membrane potential. Mitochondrial network formation and morphology was altered, with greatly reduced expression of fusogenic Opa1 isoforms. Mitochondrial alterations were also detected in cerebella of 18-month-old heterozygous mutants and may be a hallmark of disease. Pharmacological inhibition of de novo mitochondrial protein translation with chloramphenicol caused reversal of mitochondrial morphology in homozygous mutant MEFs, supporting the relevance of mitochondrial proteotoxicity for SCA28 pathogenesis and therapy development.
AB - Spinocerebellar ataxia 28 is an autosomal dominant neurodegenerative disorder caused by missense mutations affecting the proteolytic domain of AFG3L2, a major component of the mitochondrial m-AAA protease. However, little is known of the underlying pathogenetic mechanisms or how to treat patients with SCA28. Currently available Afg3l2 mutant mice harbour deletions that lead to severe, early-onset neurological phenotypes that do not faithfully reproduce the late-onset and slowly progressing SCA28 phenotype. Here we describe production and detailed analysis of a new knock-in murine model harbouring an Afg3l2 allele carrying the p.Met665Arg patient-derived mutation. Heterozygous mutant mice developed normally but adult mice showed signs of cerebellar ataxia detectable by beam test. Although cerebellar pathology was negative, electrophysiological analysis showed a trend towards increased spontaneous firing in Purkinje cells from heterozygous mutants with respect to wild-type controls. As homozygous mutants died perinatally with evidence of cardiac atrophy, for each genotype we generated mouse embryonic fibroblasts (MEFs) to investigate mitochondrial function. MEFs from mutant mice showed altered mitochondrial bioenergetics, with decreased basal oxygen consumption rate, ATP synthesis and mitochondrial membrane potential. Mitochondrial network formation and morphology was altered, with greatly reduced expression of fusogenic Opa1 isoforms. Mitochondrial alterations were also detected in cerebella of 18-month-old heterozygous mutants and may be a hallmark of disease. Pharmacological inhibition of de novo mitochondrial protein translation with chloramphenicol caused reversal of mitochondrial morphology in homozygous mutant MEFs, supporting the relevance of mitochondrial proteotoxicity for SCA28 pathogenesis and therapy development.
KW - AFG3L2
KW - Mitochondrial dynamics
KW - Mouse knock-in
KW - Proteotoxicity
KW - SCA28
UR - http://www.scopus.com/inward/record.url?scp=85056203169&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85056203169&partnerID=8YFLogxK
U2 - 10.1016/j.nbd.2018.10.018
DO - 10.1016/j.nbd.2018.10.018
M3 - Article
C2 - 30389403
AN - SCOPUS:85056203169
VL - 124
SP - 14
EP - 28
JO - Neurobiology of Disease
JF - Neurobiology of Disease
SN - 0969-9961
ER -