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Plausible pathogenesis of SCA8 CTG trinucleotide repeats expansion
538
Poster abstracts / Int. J. Devl Neuroscience 24 (2006) 495–603
cells transfected with expanded TBP revealed reduced oxidative tolerance upon t-butylhydroperoxide treatment. The reduced oxidative stress tolerance was also observed using lymphoblastoid cell lines from SCA17 patients. Proteomics analysis on transiently transfected 293 and lymphoblastoid cells with TBP expansion further suggests the involvement of proteins assisting folding and metabolism on the disease pathogenesis. The identified abnormalities in neurodegeneration may be used as a “biomarker” for assessing the efficacy of potential therapeutic strategies for SCAs and other polyglutamine diseases. Keywords: Spinocerebellar ataxia type 17; TBP expansion; Proteomics study; Biomarker; Oxidative stress doi:10.1016/j.ijdevneu.2006.09.160
doi:10.1016/j.ijdevneu.2006.09.161 [P100] Plausible pathogenesis of SCA8 CTG trinucleotide repeats expansion I.C. Chen 1,∗ , H.C Shiau 1,∗ , H.Y. Lin 1 , S.H. Kao 1 , C.M. Chen 2 , G.J. Lee-Chen 1 Taiwan Normal University, Taiwan; Memorial Hospital, Taiwan
Molecular genetic and epigenetic studies of SCA8 CTG repeat expansion G.J. Lee-Chen 1,∗ , S.Y. Huang 1 , M.L. Li 1 , Y.R. Wu 2 , C.M. Chen 2 Taiwan Normal University, Taiwan; Memorial Hospital, Taiwan
Keywords: SCA8 CTG expansion; Methylation; Epigenetic change; Proteomics study
1 National
[P99]
1 National
generation which can be used in the future to assess the efficacy of potential therapeutic strategies for SCA8 disease.
2 Chang
Gung
Koob and co-workers first identified that spinocerebellar ataxia type 8 (SCA8) was associated with a CTG repeat expansion at chromosome 13q21 with 90–250 combined CTA/CTG repeats. Since then, unrelated expanded alleles are found in familial and sporadic ataxia patients as well as in patients with other neurological disorders. The most 5 end of the SCA8 gene is transcribed through the first exon of a predicted actin organizer Kelch-like 1 (KLHL1) gene. The definite function of SCA8 and the plausible pathogenesis mechanism remain unclear. Previously, we assessed the CTG repeat size ranges in our populations and found expanded alleles in patients with ataxia and other neurological diseases. This results support the notion that the spectrum of clinical presentations of SCA8 is broad. Nevertheless, this speculation needs further evidence from large-series, longitudinal, and clinical studies. Using the CpG island identifier software, an apparent CpG island was observed within the overlapped exon 1 region between SCA8 and KLHL1 genes. To explore the plausible epigenetic control of the disease presentation, aberrant methylation was assessed by methylation specific PCR assay and restriction enzyme based-methylation assay using lymphoblastoid cells with normal or expanded CTG repeats. The results revealed differential methylation of the overlapped exon 1 region among different individuals. However, CTG repeat length-dependent methylation was not observed. The variation of methylation pattern might explain the incomplete penetrance of the disease, as expanded alleles do not always co-segregate with the disease phenotype in some affected families. In addition, RT-PCR analysis revealed that both SCA8 and KLHL1 were expressed in lymphoblastoid cells. The ongoing proteomics analysis on lymploblastoid cells carrying normal or expanded CTG repeats may identify abnormalities in neurode-
2 Chang
Gung
The mutation causing spinocerebellar ataxia type 8 (SCA8) has been identified as a CTG repeats expansion in the 3 region of the SCA8 gene, which overlaps the 5 region of the Kelchlike 1 (KLHL1) gene. Unrelated expanded alleles were found in patients with Parkinson’s disease in our population, in addition to familial and sporadic ataxia patients. We cloned the SCA8 cDNA with 0, 23, 88 and 157 CTA/CTG combined repeats as well as full-length KLHL1 and 5 254-bp CAG repeatscontaining TBP cDNA and used to uncover the plausible pathogenesis using human embryonic kidney cells and rat primary cultured cerebellar neurons. Co-expressing SCA8 and GFPtagged KLHL1 in 293 cells and FACS analysis revealed a repeat length-independent negative regulation of KLHL1. RNA fluorescent in situ hybridization and confocal microscopy examination revealed ribonuclear foci formation in cells carrying expanded repeats and the expression of CAG repeat-containing RNA was down-regulated. Proteomic analysis on transiently transfected cell models suggests the involvement of proteins assisting folding and RNA splicing in the pathogenesis of SCA8 CTG expansion. Thus, expanded SCA8 CUG repeats may interact with yet to be identified proteins to disrupt normal cellular functions. Keywords: SCA8 CTG expansion; Nuclei foci; trans Antisense effect; Proteomics study doi:10.1016/j.ijdevneu.2006.09.162 [P101] Apolipoprotein E, angiotensin-converting enzyme and kallikrein gene polymorphisms and the risk of Alzheimer’s disease and vascular dementia H.K. Wang 1,∗ , C.M. Chen 2 , H.C. Fung 2 , W.C. Hsu 2 , G.J. Lee-Chen 1 1 National
Taiwan Normal University, Taiwan; Memorial Hospital, Taiwan
2 Chang
Gung
Alzheimer’s disease (AD) and vascular dementia (VaD) are the most prevalent forms of dementia. Lipoproteins and vascular
Poster abstracts / Int. J. Devl Neuroscience 24 (2006) 495–603
cells transfected with expanded TBP revealed reduced oxidative tolerance upon t-butylhydroperoxide treatment. The reduced oxidative stress tolerance was also observed using lymphoblastoid cell lines from SCA17 patients. Proteomics analysis on transiently transfected 293 and lymphoblastoid cells with TBP expansion further suggests the involvement of proteins assisting folding and metabolism on the disease pathogenesis. The identified abnormalities in neurodegeneration may be used as a “biomarker” for assessing the efficacy of potential therapeutic strategies for SCAs and other polyglutamine diseases. Keywords: Spinocerebellar ataxia type 17; TBP expansion; Proteomics study; Biomarker; Oxidative stress doi:10.1016/j.ijdevneu.2006.09.160
doi:10.1016/j.ijdevneu.2006.09.161 [P100] Plausible pathogenesis of SCA8 CTG trinucleotide repeats expansion I.C. Chen 1,∗ , H.C Shiau 1,∗ , H.Y. Lin 1 , S.H. Kao 1 , C.M. Chen 2 , G.J. Lee-Chen 1 Taiwan Normal University, Taiwan; Memorial Hospital, Taiwan
Molecular genetic and epigenetic studies of SCA8 CTG repeat expansion G.J. Lee-Chen 1,∗ , S.Y. Huang 1 , M.L. Li 1 , Y.R. Wu 2 , C.M. Chen 2 Taiwan Normal University, Taiwan; Memorial Hospital, Taiwan
Keywords: SCA8 CTG expansion; Methylation; Epigenetic change; Proteomics study
1 National
[P99]
1 National
generation which can be used in the future to assess the efficacy of potential therapeutic strategies for SCA8 disease.
2 Chang
Gung
Koob and co-workers first identified that spinocerebellar ataxia type 8 (SCA8) was associated with a CTG repeat expansion at chromosome 13q21 with 90–250 combined CTA/CTG repeats. Since then, unrelated expanded alleles are found in familial and sporadic ataxia patients as well as in patients with other neurological disorders. The most 5 end of the SCA8 gene is transcribed through the first exon of a predicted actin organizer Kelch-like 1 (KLHL1) gene. The definite function of SCA8 and the plausible pathogenesis mechanism remain unclear. Previously, we assessed the CTG repeat size ranges in our populations and found expanded alleles in patients with ataxia and other neurological diseases. This results support the notion that the spectrum of clinical presentations of SCA8 is broad. Nevertheless, this speculation needs further evidence from large-series, longitudinal, and clinical studies. Using the CpG island identifier software, an apparent CpG island was observed within the overlapped exon 1 region between SCA8 and KLHL1 genes. To explore the plausible epigenetic control of the disease presentation, aberrant methylation was assessed by methylation specific PCR assay and restriction enzyme based-methylation assay using lymphoblastoid cells with normal or expanded CTG repeats. The results revealed differential methylation of the overlapped exon 1 region among different individuals. However, CTG repeat length-dependent methylation was not observed. The variation of methylation pattern might explain the incomplete penetrance of the disease, as expanded alleles do not always co-segregate with the disease phenotype in some affected families. In addition, RT-PCR analysis revealed that both SCA8 and KLHL1 were expressed in lymphoblastoid cells. The ongoing proteomics analysis on lymploblastoid cells carrying normal or expanded CTG repeats may identify abnormalities in neurode-
2 Chang
Gung
The mutation causing spinocerebellar ataxia type 8 (SCA8) has been identified as a CTG repeats expansion in the 3 region of the SCA8 gene, which overlaps the 5 region of the Kelchlike 1 (KLHL1) gene. Unrelated expanded alleles were found in patients with Parkinson’s disease in our population, in addition to familial and sporadic ataxia patients. We cloned the SCA8 cDNA with 0, 23, 88 and 157 CTA/CTG combined repeats as well as full-length KLHL1 and 5 254-bp CAG repeatscontaining TBP cDNA and used to uncover the plausible pathogenesis using human embryonic kidney cells and rat primary cultured cerebellar neurons. Co-expressing SCA8 and GFPtagged KLHL1 in 293 cells and FACS analysis revealed a repeat length-independent negative regulation of KLHL1. RNA fluorescent in situ hybridization and confocal microscopy examination revealed ribonuclear foci formation in cells carrying expanded repeats and the expression of CAG repeat-containing RNA was down-regulated. Proteomic analysis on transiently transfected cell models suggests the involvement of proteins assisting folding and RNA splicing in the pathogenesis of SCA8 CTG expansion. Thus, expanded SCA8 CUG repeats may interact with yet to be identified proteins to disrupt normal cellular functions. Keywords: SCA8 CTG expansion; Nuclei foci; trans Antisense effect; Proteomics study doi:10.1016/j.ijdevneu.2006.09.162 [P101] Apolipoprotein E, angiotensin-converting enzyme and kallikrein gene polymorphisms and the risk of Alzheimer’s disease and vascular dementia H.K. Wang 1,∗ , C.M. Chen 2 , H.C. Fung 2 , W.C. Hsu 2 , G.J. Lee-Chen 1 1 National
Taiwan Normal University, Taiwan; Memorial Hospital, Taiwan
2 Chang
Gung
Alzheimer’s disease (AD) and vascular dementia (VaD) are the most prevalent forms of dementia. Lipoproteins and vascular