Biological effects of the PINK1 c.1366C>T mutation: implications in Parkinson disease pathogenesis.
PINK1 gene mutations are a cause of recessively inherited, early-onset Parkinson's disease. In some patients, a single heterozygous mutation has been identified, including the recurrent c.1366C>T transition. The interpretation of this finding remains controversial. Furthermore, the c.1366C>T mutation is associated with lower levels of PINK1 transcript, raising the question of whether mRNA levels correlate with the clinical status. We sequenced genomic DNA and copy DNA (cDNA) from 20 subjects carrying the c.1366C>T mutation in the homozygous (n = 5) or heterozygous (n = 15) state. In 17 mutation carriers, messenger RNA (mRNA) was quantified by real-time PCR using four different assays (PINK1 exon 5-6 or exon 7-8 relative to control genes SDHA or YWHAZ). Genomic sequencing confirmed the presence and zygosity of PINK1 mutations. cDNA sequencing in heterozygous mutation carriers revealed a strong wild-type and a much weaker or almost absent mutant signal, whereas in the homozygous patients, only the mutant signal was detected. Homozygous and heterozygous carriers showed PINK1 mRNA levels relative to a reference gene in the range of 0.1-0.2 and 0.5-0.6, respectively, compared with values of 0.9-1.0 in mutation-negative individuals. Treatment of lymphoblasts from a heterozygous mutation carrier with cycloheximide markedly increased the mutant transcript signal. We conclude that the recurrent PINK1 c.1366C>T mutation exerts a major effect at the mRNA level (80-90% reduction), most likely via nonsense-mediated mRNA decay. The absence of correlation between PINK1 mRNA levels and clinical status in heterozygous mutation carriers suggests that other genetic or environmental factors play a role in determining the phenotypic variability associated with the c.1366C>T mutation.
Grünewald
Anne
A
Department of Neurology, University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany.
Breedveld
Guido J
GJ
Lohmann-Hedrich
Katja
K
Rohé
Christan F
CF
König
Inke R
IR
Hagenah
Johann
J
Vanacore
Nicola
N
Meco
Giuseppe
G
Antonini
Angelo
A
Goldwurm
Stefano
S
Lesage
Suzanne
S
Dürr
Alexandra
A
Binkofski
Ferdinand
F
Siebner
Hartwig
H
Münchau
Alexander
A
Brice
Alexis
A
Oostra
Ben A
BA
Klein
Christine
C
Bonifati
Vincenzo
V
D001483:Base Sequence; D003596:Cytosine; D018076:DNA, Complementary / Q000235:genetics; D005190:Family; D005260:Female; D006580:Genetic Carrier Screening; D006720:Homozygote; D006801:Humans; D008297:Male; D009154:Mutation; D010300:Parkinson Disease / Q000201:enzymology / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods; D020641:Polymorphism, Single Nucleotide; D011494:Protein Kinases / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D013941:Thymine; D000099202:PTEN-Induced Putative Kinase
D003596:Cytosine; D018076:DNA, Complementary; D011494:Protein Kinases; D012333:RNA, Messenger; D013941:Thymine; D000099202:PTEN-Induced Putative Kinase