Novel SPG11 mutations in Asian kindreds and disruption of spatacsin function in the zebrafish.
Autosomal recessive hereditary spastic paraplegia with thin corpus callosum (HSP-TCC) maps to the SPG11 locus in the majority of cases. Mutations in the KIAA1840 gene, encoding spatacsin, have been shown to underlie SPG11-linked HSP-TCC. The aim of this study was to perform candidate gene analysis in HSP-TCC subjects from Asian families and to characterize disruption of spatacsin function during zebrafish development. Homozygosity mapping and direct sequencing were used to assess the ACCPN, SPG11, and SPG21 loci in four inbred kindreds originating from the Indian subcontinent. Four novel homozygous SPG11 mutations (c.442+1G>A, c.2146C>T, c.3602_3603delAT, and c.4846C>T) were identified, predicting a loss of spatacsin function in each case. To investigate the role of spatacsin during development, we additionally ascertained the complete zebrafish spg11 ortholog by reverse transcriptase PCR and 5′ RACE. Analysis of transcript expression through whole-mount in situ hybridization demonstrated ubiquitous distribution, with highest levels detected in the brain. Morpholino antisense oligonucleotide injection was used to knock down spatacsin function in zebrafish embryos. Examination of spg11 morphant embryos revealed a range of developmental defects and CNS abnormalities, and analysis of axon pathway formation demonstrated an overall perturbation of neuronal differentiation. These data confirm loss of spatacsin as the cause of SPG11-linked HSP-TCC in Asian kindreds, expanding the mutation spectrum recognized in this disorder. This study represents the first investigation in zebrafish addressing the function of a causative gene in autosomal recessive HSP and identifies a critical role for spatacsin during early neural development in vivo.
Southgate
Laura
L
Department of Medical and Molecular Genetics, King's College London, School of Medicine, Floor 8 Tower Wing, Guy's Hospital, London, SE1 9RT, UK.
Dafou
Dimitra
D
Hoyle
Jacqueline
J
Li
Nan
N
Kinning
Esther
E
Critchley
Peter
P
Németh
Andrea H
AH
Talbot
Kevin
K
Bindu
Parayil S
PS
Sinha
Sanjib
S
Taly
Arun B
AB
Raghavendra
Seetharam
S
Müller
Ferenc
F
Maher
Eamonn R
ER
Trembath
Richard C
RC
D048868:Adaptor Proteins, Signal Transducing; D000293:Adolescent; D000328:Adult; D000595:Amino Acid Sequence; D000818:Animals; D044466:Asian People; D002352:Carrier Proteins / Q000235:genetics*; D005260:Female; D006801:Humans; D007194:India; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D011506:Proteins / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D015027:Zebrafish
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D011506:Proteins; C520412:SPG11 protein, human; C424703:SPG21 protein, human
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