The taxonomic position and the unexpected divergence of the Habu viper, Protobothrops among Japanese subtropical islands.

There are four Habu species currently recognized in Japan: Protobothrops flavoviridis from the Amami Islands and the Okinawa Islands, P. tokarensis from the Tokara Islands, P. elegans from the Yaeyama Islands and Ovophis okinabvensis from the Amami Islands and the Okinawa Islands. To clarify their taxonomic positions, we determined the complete mitochondria genome sequence (approx. 17kb) from two specimens from two different islands each for P. flavoviridis, P. tokarensis and P. elegans as well as one specimen of O. okinavensis and reconstructed the molecular phylogeny of Protobothrops using the published sequences of related species. The maximum likelihood tree showed four major species groups within Protbothrops: Group I consisting of P. cornutus, P. dabieshanensis, P. jerdonii and P. xiangchengensis; Group II consisting of P. flavoviridis and P. tokarensis; Group III consisting of P. maolensis, P. mucrosquamatus and P. elegans; Group IV consisting of P. himalayanus and P. kaubacki. Since we observed an unexpected divergence and the paraphyly of the two samples of P. flavoviridis collected from different islands, Amami-Oshima and Okinawajima within the Group II, we expanded the analysis by increasing the number of P. flavoviridis and P. tokarensis collected from 10 islands: Amami-Oshima (5 specimens), Kakeromajima (4) and Tokunoshima (4) from the Amami Islands, Okinawajima (4), Iheyajima (4), Iejima (4), Tokashikijima (4) and Kumejima (4) from the Okinawa Islands, Kodakarajima (P. tokarensis) (4) and Takarajima (P. tokarensis) (4) from the Tokara Islands. The maximum likelihood tree of the 44 samples replicated the significant divergence of P. flavoviridis between the Amami Clade including Amami-Oshima, Kakeromajima and Tokunoshima and the Okinawa Clade including Okinawajima, Iheyajima, Iejima, Tokashikijima and Kumejima. The Amami Clade also include all specimens from the Tokara Islands currently known as an independent species, P. tokarensis, suggesting the paraphyly of the taxon, P. flavoviridis. In contrast, we observed a distinct lineage of the two specimens from the Yaeyama Islands, supporting the validity of the taxon, P. elegans as an independent species. By MCMC method, we estimated the divergence time between the Amami Clade and the Okinawa Clade to be 6.51MYA, suggesting that the vicariance of the two clades preceded the geological separation of the Amami Islands and the Okinawa Islands (∼1.5MYA). As expected from the limited mobility of terrestrial reptiles including snakes, we observed high genetic divergence in Habu mtDNA among Japanese subtropical island populations.

Amphiphysin I but not dynamin I nor synaptojanin mRNA expression increased after repeated methamphetamine administration in the rat cerebrum and cerebellum.

Dopamine increases/decreases synaptic vesicle recycling and in schizophrenia the proteins/mRNA is decreased. We isolated cDNA clone, similar to amphiphysin 1 (vesicle protein) mRNA from the neocortex of rats injected repeatedly with methamphetamine using polymerase chain reaction (PCR) differential display. This clone is highly homologous to the 3' region of the human amphiphysin gene. PCR extension study using a primer specific for the rat amphiphysin 1 gene and a primer located within the clone revealed that it is the 3' UTR region of the rat amphiphysin 1 gene. Furthermore, in situ hybridization revealed that amphiphysin 1 mRNA is expressed in the cerebrum, medial thalamus, hippocampus and cerebellum. In the cerebellum, amphiphysin mRNA expression was confined to upper granule cell layer. Repeated methamphetamine administration increased amphiphysin I mRNA expression in both anterior part of the cerebrum, and the cerebellum. However, the repeated administration did not alter mRNA expression of the other vesicle proteins, synaptotagmin I, synapsin I, synaptojanin and dynamin I, we conclude that the repeated administration selectively increased amphiphysin 1 mRNA expression. Thus, amphiphysin 1 does not work as synaptic recycling, but it is suggested, as a part of pathogenesis of brain tissue injury (under Ca²âº and Mg²âº devoid environment) in repeated methamphetamine-injected states, the gene regulate actin-asssembly, learning, cell stress signaling and cell polarity.

Partial SPAST and DPY30 deletions in a Japanese spastic paraplegia type 4 family.

Spastic paraplegia type 4 (SPG4) is the most common autosomal dominant hereditary SPG caused by mutations in the SPAST gene. We studied the four-generation pedigree of a Japanese family with autosomal dominant hereditary SPG both clinically and genetically. Twelve available family members (ten affected; two unaffected) and two spouses were enrolled in the study. The clinical features were hyperreflexia in all four limbs, spasticity of the lower extremities, impaired vibration sense, mild cognitive impairment confirmed by the Wechsler Adult Intelligence Scale-Third Edition, and peripheral neuropathy confirmed by neurophysiological examinations. All four female patients experienced miscarriages. The cerebrospinal fluid tau levels were mildly increased in two of three patients examined. Linkage analyses revealed the highest logarithm of odds score of 2.64 at 2p23-p21 where the SPAST gene is located. Mutation scanning of the entire exonic regions of the SPAST gene by direct sequencing revealed no mutations. Exonic copy number analysis by real-time quantitative polymerase chain reaction revealed heterozygous deletion of exons 1 to 4 of the SPAST gene. Breakpoint analysis showed that the centromeric breakpoint was located within intron 4 of SPAST while the telomeric breakpoint was located within intron 3 of the neighboring DPY30 gene, causing a deletion of approximately 70 kb ranging from exons 1 to 3 of DPY30 to exons 1 to 4 of SPAST. To our knowledge, this is the first report of SPG4 associated with partial deletions of both the SPAST and DPY30 genes. The partial heterozygous deletion of DPY30 could modify the phenotypic expression of SPG4 patients with this pedigree.

DNA genome of spontaneously occurring deletion mutants of herpes simplex virus type 1 lacking one copy of the inverted repeat sequences of the L component.

Three non-engineered, spontaneously occurring herpes simplex virus type 1 (HSV-1) mutants (GN52, GN82, and GN91) that have a deletion of approximately 10 kbp (including a part of the UL55 gene, the entire UL56 gene, and one copy of the inverted repeat sequences of the L component (R(L))) and retain the a sequence were isolated. The yields of the mutants at 24 h post-adsorption in cultured cells were comparable to that of an HSV-1 isolate (GN28) without the deletion. Although the three mutants lost one copy of R(L), the L component in replicative intermediates of the mutants inverted. DNA replicative intermediates of the three mutants were flanked by the L component, like those of GN28. The three mutants were generated through recombination involving regions around the authentic cleavage site in the a sequence, suggesting an important role of the a sequence in the diversification of herpesviruses.

Positive association of phencyclidine-responsive genes, PDE4A and PLAT, with schizophrenia.

As schizophrenia-like symptoms are produced by administration of phencyclidine (PCP), a noncompetitive antagonist of N-methyl-D-aspartate (NMDA) receptors, PCP-responsive genes could be involved in the pathophysiology of schizophrenia. We injected PCP to Wistar rats and isolated five different parts of the brain in 1 and 4 hr after the injection. We analyzed the gene expression induced by the PCP treatment of these tissues using the AGILENT rat cDNA microarray system. We observed changes in expression level in 90 genes and 21 ESTs after the treatment. Out of the 10 genes showing >2-fold expressional change evaluated by qRT-PCR, we selected 7 genes as subjects for the locus-wide association study to identify susceptibility genes for schizophrenia in the Japanese population. In haplotype analysis, significant associations were detected in combinations of two SNPs of BTG2 (P = 1.4 × 10(-6) ), PDE4A (P = 1.4 × 10(-6) ), and PLAT (P = 1 × 10(-3) ), after false discovery rate (FDR) correction. Additionally, we not only successfully replicated the haplotype associations in PDE4A (P = 6.8 × 10(-12) ) and PLAT (P = 0.015), but also detected single-point associations of one SNP in PDE4A (P = 0.0068) and two SNPs in PLAT (P = 0.0260 and 0.0104) in another larger sample set consisting of 2,224 cases and 2,250 controls. These results indicate that PDE4A and PLAT may be susceptibility genes for schizophrenia in the Japanese population.

Multiple system degeneration with basophilic inclusions in Japanese ALS patients with FUS mutation.

Mutations in the fused in sarcoma gene (FUS) were recently found in patients with familial amyotrophic lateral sclerosis (ALS). The present study aimed to clarify unique features of familial ALS caused by FUS mutation in the Japanese population. We carried out clinical, neuropathological, and genetic studies on a large Japanese pedigree with familial ALS. In six successive generations of this family, 16 individuals of both sexes were affected by progressive muscle atrophy and weakness, indicating an autosomal dominant trait. Neurological examination of six patients revealed an age at onset of 48.2+/-8.1 years in fourth generation patients, while it was 31 and 20 years in fifth and sixth generation patients, respectively. Motor paralysis progressed rapidly in these patients, culminating in respiratory failure within 1 year. The missense mutation c.1561 C>T (p.R521C) was found in exon 15 of FUS in the four patients examined. Neuropathological study of one autopsied case with the FUS mutation revealed multiple system degeneration in addition to upper and lower motor neuron involvement: the globus pallidus, thalamus, substantia nigra, cerebellum, inferior olivary nucleus, solitary nucleus, intermediolateral horn, Clarke's column, Onuf's nucleus, central tegmental tract, medial lemniscus, medial longitudinal fasciculus, superior cerebellar peduncle, posterior column, and spinocerebellar tract were all degenerated. Argyrophilic and basophilic neuronal or glial cytoplasmic inclusions immunoreactive for FUS, GRP78/BiP, p62, and ubiquitin were detected in affected lesions. The FUS R521C mutation in this Japanese family caused familial ALS with pathological features of multiple system degeneration and neuronal basophilic inclusions.

Repeated administration of methamphetamine blocked cholecystokinin-octapeptide injection-induced c-fos mRNA expression without change in capsaicin-induced junD mRNA expression in rat cerebellum.

In the cerebellum, there are numerous cholecystokinin (CCK-8)-containing fibers. Since systemic CCK-8 injection-induced anxiety (psychological stress) activates the locus coeruleus cells that send mossy fiber inputs to the cerebellum, we examined whether systemic CCK-8 injections activate the rat and mouse cerebellum. First, injections of CCK-8 were found to induce c-fos mRNA expression in a vague patchy pattern that is different from single methamphetamine-induced Zebrin band-like c-fos mRNA expression, suggesting that the CCK-8 activating mossy fibers induce gene expression differently from the dopamine-containing mossy fibers in the ventral tegmental area. Second, since CCK-8 facilitates neural activity of dopamine in the midbrain, we examined whether repeated methamphetamine administration that induced behavioral sensitization had similar effects on the cerebellar CCK system. Repeated administration of methamphetamine suppressed the CCK-8-induced c-fos mRNA expression in the rat cerebellum. Third, capsaicin injections (physical stress) into a hind limb of the rat increased junD mRNA expression with no effect on c-fos mRNA expression, and repeated methamphetamine injections had no effect on the capsaicin-induced expression of junD mRNA. Fourth, either single injection of methamphetamine or CCK-8 to mice increased c-fos mRNA expression in the locus coeruleus, and so noradrenalin, but not dopamine, might interact with CCK-8-activating system. However, we considered the possibility unlikely. Thus, we conclude that repeated methamphetamine administration though dopamine selectively inhibits the c-fos mRNA expression after CCK-8 injection in the cerebellum.

Discovery of the Gene Encoding a Novel Small Serum Protein (SSP) of Protobothrops flavoviridis and the Evolution of SSPs.

Small serum proteins (SSPs) are low-molecular-weight proteins in snake serum with affinities for various venom proteins. Five SSPs, PfSSP-1 through PfSSP-5, have been reported in Protobothrops flavoviridis ("habu", Pf) serum so far. Recently, we reported that the five genes encoding these PfSSPs are arranged in tandem on a single chromosome. However, the physiological functions and evolutionary origins of the five SSPs remain poorly understood. In a detailed analysis of the habu draft genome, we found a gene encoding a novel SSP, SSP-6. Structural analysis of the genes encoding SSPs and their genomic arrangement revealed the following: (1) SSP-6 forms a third SSP subgroup; (2) SSP-5 and SSP-6 were present in all snake genomes before the divergence of non-venomous and venomous snakes, while SSP-4 was acquired only by venomous snakes; (3) the composition of paralogous SSP genes in snake genomes seems to reflect snake habitat differences; and (4) the evolutionary emergence of SSP genes is probably related to the physiological functions of SSPs, with an initial snake repertoire of SSP-6 and SSP-5. SSP-4 and its derivative, SSP-3, as well as SSP-1 and SSP-2, appear to be venom-related and were acquired later.

The identification and functional implications of human-specific "fixed" amino acid substitutions in the glutamate receptor family.

BACKGROUND: The glutamate receptors (GluRs) play a vital role in the mediation of excitatory synaptic transmission in the central nervous system. To clarify the evolutionary dynamics and mechanisms of the GluR genes in the lineage leading to humans, we determined the complete sequences of the coding regions and splice sites of 26 chimpanzee GluR genes. RESULTS: We found that all of the reading frames and splice sites of these genes reported in humans were completely conserved in chimpanzees, suggesting that there were no gross structural changes in humans after their divergence from the human-chimpanzee common ancestor. We observed low KA/KS ratios in both humans and chimpanzees, and we found no evidence of accelerated evolution. We identified 30 human-specific "fixed" amino acid substitutions in the GluR genes by analyzing 80 human samples of seven different populations worldwide. Grantham's distance analysis showed that GRIN2C and GRIN3A are the most and the second most diverged GluR genes between humans and chimpanzees. However, most of the substitutions are non-radical and are not clustered in any particular region. Protein motif analysis assigned 11 out of these 30 substitutions to functional regions. Two out of these 11 substitutions, D71G in GRIN3A and R727H in GRIN3B, caused differences in the functional assignments of these genes between humans and other apes. CONCLUSION: We conclude that the GluR genes did not undergo drastic changes such as accelerated evolution in the human lineage after the divergence of chimpanzees. However, there remains a possibility that two human-specific "fixed" amino acid substitutions, D71G in GRIN3A and R727H in GRIN3B, are related to human-specific brain function.

Serologic and genotypic analysis of a series of herpes simplex virus type 1 isolates from two patients with genital herpes.

Herpes simplex virus type 1 (HSV-1) has been reported increasingly as a cause of genital herpes, although HSV-1 is usually associated with oro-labial herpes. In the present study, serum specimens and materials for viral isolation were obtained serially from two patients with recrudescent HSV-1 genital infections to study serology and molecular epidemiology. Recurrent episodes, during which HSV-1 was isolated, were followed by an increase in the level of anti-HSV-1 antibody, suggesting a booster effect from re-exposure to viral antigens and the possible usefulness of the variation in the level of anti-HSV-1 antibody to diagnose recurrence. While genotypes of HSV-1 isolates obtained from one patient were different from those from the other patient, genotypes of sequential HSV-1 isolates obtained from the same patient were the same, implying that the recrudescent genital lesions of the two patients could be attributed to endogenous recurrence of a latent virus. Sera from one patient neutralized HSV-1 isolates obtained from the other patient as well as HSV-1 isolates obtained from the same patient. An HSV-1 isolate obtained during a later episode in one patient was neutralized by sera taken before/during the later episode of the same patient, as effectively as an HSV-1 isolate obtained during an earlier episode in the same patient; thus, in these two cases, HSV-1 was assumed to have multiplied during recurrence despite the presence of an anti-HSV-1 antibody that could neutralize experimentally HSV-1.

Association study of polymorphisms in the group III metabotropic glutamate receptor genes, GRM4 and GRM7, with schizophrenia.

Based on the hypothesis that a glutamatergic dysfunction is involved in the pathophysiology of schizophrenia, we have been conducting systematic studies on the association between glutamate receptor genes and schizophrenia. Here we report association studies of schizophrenia with polymorphisms in group III metabotropic glutamate receptor genes, GRM4 and GRM7. We selected 8 and 43 common SNPs distributed in the entire gene regions of GRM4 (>111 kb) and GRM7 (>900 kb), respectively. We scanned significant associations with schizophrenia using 100 case-control pairs of Japanese. We identified two neighboring SNPs (rs12491620 and rs1450099) in GRM7 showing highly significant haplotype association with schizophrenia surviving the FDR correction. We then performed additional typing of the two SNPs using the expanded sample set (404 cases and 420 controls) and confirmed the significant association with the disease. We conclude that at least one susceptibility locus for schizophrenia is located within or nearby GRM7, whereas GRM4 is unlikely to be a major susceptibility gene for schizophrenia in the Japanese population.

Alternative mRNA Splicing in Three Venom Families Underlying a Possible Production of Divergent Venom Proteins of the Habu Snake, Protobothrops flavoviridis.

Snake venoms are complex mixtures of toxic proteins encoded by various gene families that function synergistically to incapacitate prey. A huge repertoire of snake venom genes and proteins have been reported, and alternative splicing is suggested to be involved in the production of divergent gene transcripts. However, a genome-wide survey of the transcript repertoire and the extent of alternative splicing still remains to be determined. In this study, the comprehensive analysis of transcriptomes in the venom gland was achieved by using PacBio sequencing. Extensive alternative splicing was observed in three venom protein gene families, metalloproteinase (MP), serine protease (SP), and vascular endothelial growth factors (VEGF). Eleven MP and SP genes and a VEGF gene are expressed as a total of 81, 61, and 8 transcript variants, respectively. In the MP gene family, individual genes are transcribed into different classes of MPs by alternative splicing. We also observed trans-splicing among the clustered SP genes. No other venom genes as well as non-venom counterpart genes exhibited alternative splicing. Our results thus indicate a potential contribution of mRNA alternative and trans-splicing in the production of highly variable transcripts of venom genes in the habu snake.

A unique case of fibrodysplasia ossificans progressiva with an ACVR1 mutation, G356D, other than the common mutation (R206H).

Fibrodysplasia ossificans progressiva (FOP) is a rare autosomal dominant congenital disease characterized by progressive heterotopic endochondral osteogenesis with great-toe malformations. A 617G > A (R206H) mutation of the activin A type 1 receptor gene (ACVR1) has been found in all previously reported patients with FOP. Thus, this is one of the most specific of all disease-associated mutations. We report here on a 62-year-old man with slowly progressive FOP and a novel mutation in ACVR1. He developed difficulty in moving his shoulder since age 10 years due to contraction of the shoulder joint. The symptoms progressed slowly, and he could not walk at age 36 years and was bedridden at 55 years. He also showed rigid spine, baldness, sensorineural hearing loss, and hypodactyly accompanied by abnormal ectopic ossification. Analysis of ACVR1 and its cDNA revealed that the patient is heterozygous for a mutation, 1067G > A (G356D). Typing of SNPs located in the approximately 0.5-Mb region spanning ACVR1 and its neighbor genes suggested that 1067G > A is a de novo mutation. These results give a clue to better understanding of FOP as well as of the mild clinical symptoms in the patient.

Hereditary motor and sensory neuropathy with proximal dominancy in the lower extremities, urinary disturbance, and paroxysmal dry cough.

We studied a four-generation pedigree of a Japanese family with hereditary neuropathy to elucidate the genetic basis of this disease. Twelve members of the family were enrolled in this study. The clinical features were neurogenic muscle weakness with proximal dominancy in the lower extremities, sensory involvement, areflexia, fine postural tremors, painful muscle cramps, elevated creatine kinase levels, recurrent paroxysmal dry cough, and neurogenic bladder. We performed a genome-wide search using genetic loci spaced at about 13 Mb intervals. Although nine chromosomes (1, 3, 4, 5, 6, 10, 17, 19, and 22) had at least one region in which the logarithm of odds (LOD) score was over 1.0, no loci fulfilled the criteria for significant evidence of linkage. Moreover, we analyzed an extra 14 markers on 3p12-q13 (the locus of hereditary motor and sensory neuropathy, proximal dominant form) and an extra five markers on 3p22-p24 (the locus of hereditary sensory neuropathy with chronic cough) and observed LOD scores of <-3 on both 3p12-q13 and 3p22-p24. Mutation scanning of the entire coding regions of the MPZ and PMP22 genes revealed no mutations. We conclude that the disorder described here is a newly classified hereditary motor and sensory neuropathy with autosomal dominant inheritance.

Association study of polymorphisms in the neutral amino acid transporter genes SLC1A4, SLC1A5 and the glycine transporter genes SLC6A5, SLC6A9 with schizophrenia.

BACKGROUND: Based on the glutamatergic dysfunction hypothesis for schizophrenia pathogenesis, we have been performing systematic association studies of schizophrenia with the genes involved in glutametergic transmission. We report here association studies of schizophrenia with SLC1A4, SLC1A5 encoding neutral amino acid transporters ASCT1, ASCT2, and SLC6A5, SLC6A9 encoding glycine transporters GLYT2, GLYT1, respectively. METHODS: We initially tested the association of 21 single nucleotide polymorphisms (SNPs) distributed in the four gene regions with schizophrenia using 100 Japanese cases-control pairs and examined allele, genotype and haplotype association with schizophrenia. The observed nominal significance were examined in the full-size samples (400 cases and 420 controls). RESULTS: We observed nominally significant single-marker associations with schizophrenia in SNP2 (P = 0.021) and SNP3 (P = 0.029) of SLC1A4, SNP1 (P = 0.009) and SNP2 (P = 0.022) of SLC6A5. We also observed nominally significant haplotype associations with schizophrenia in the combinations of SNP2-SNP7 (P = 0.037) of SLC1A4 and SNP1-SNP4 (P = 0.043) of SLC6A5. We examined all of the nominal significance in the Full-size Sample Set, except one haplotype with insufficient LD. The significant association of SNP1 of SLC6A5 with schizophrenia was confirmed in the Full-size Sample Set (P = 0.018). CONCLUSION: We concluded that at least one susceptibility locus for schizophrenia may be located within or nearby SLC6A5, whereas SLC1A4, SLC1A5 and SLC6A9 are unlikely to be major susceptibility genes for schizophrenia in the Japanese population.

The habu genome reveals accelerated evolution of venom protein genes.

Evolution of novel traits is a challenging subject in biological research. Several snake lineages developed elaborate venom systems to deliver complex protein mixtures for prey capture. To understand mechanisms involved in snake venom evolution, we decoded here the ~1.4-Gb genome of a habu, Protobothrops flavoviridis. We identified 60 snake venom protein genes (SV) and 224 non-venom paralogs (NV), belonging to 18 gene families. Molecular phylogeny reveals early divergence of SV and NV genes, suggesting that one of the four copies generated through two rounds of whole-genome duplication was modified for use as a toxin. Among them, both SV and NV genes in four major components were extensively duplicated after their diversification, but accelerated evolution is evident exclusively in the SV genes. Both venom-related SV and NV genes are significantly enriched in microchromosomes. The present study thus provides a genetic background for evolution of snake venom composition.

Association study of polymorphisms in the GluR7, KA1 and KA2 kainate receptor genes (GRIK3, GRIK4, GRIK5) with schizophrenia.

On the basis of the glutamatergic dysfunction hypothesis of schizophrenia, we have been conducting a systematic study of the association of glutamate receptor genes with schizophrenia. Here we report association studies of schizophrenia with polymorphisms in three kainate receptor genes: GRIK3, GRIK4 and GRIK5. We selected 16, 24 and 5 common single nucleotide polymorphisms (SNPs) distributed in the entire gene regions of GRIK3 (>240 kb), GRIK4 (>430 kb) and GRIK5 (>90 kb), respectively. We tested associations of the polymorphisms with schizophrenia using 100 Japanese case-control pairs (the Kyushu set). We observed no significant "single marker" associations with the disease in any of the 45 SNPs tested except for one (rs3767092) in GRIK3 showing a nominal level of significance. The significant association, however, disappeared after the application of the Bonferroni correction. We also observed significant haplotype associations in seven SNP pairs in GRIK3 and in four SNP pairs in GRIK4. None, however, remained significant after Bonferroni correction. We also failed to replicate the nominally significant haplotype associations in a second sample set, the Aichi set (106 cases and 100 controls). We conclude that SNPs in the gene regions of GRIK3, GRIK4 or GRIK5 do not play a major role in schizophrenia pathogenesis in the Japanese population.

An improved method for Southern DNA and Northern RNA blotting using a Mupid-2 Mini-Gel electrophoresis unit.

An improved method for Southern DNA and Northern RNA blotting using the Mupid-2 Mini-Gel System is described. We get sharp and clear bands in Southern and Northern blotting after only 30 min short gel electrophoresis instead of the several hours large gel electrophoresis of conventional methods. The high electrical voltage with a pulse-like current of the Mupid-2 Mini-Gel System also allows reduction of the amount of formaldehyde, a harmful reagent, from the gel running buffer in RNA blotting. This minor modification of DNA and RNA blotting technique enables us to perform the complete experimental procedure more quickly economically in less space, than conventional Southern and Northern blotting, as well as using an extremely small amount of formaldehyde in RNA blotting.

Some flavonoids and DHEA-S prevent the cis-effect of expanded CTG repeats in a stable PC12 cell transformant.

Expanded CUG triplet repeats carrying mRNA seem to be responsible for myotonic dystrophy type 1 (DM1). To study the pathogenesis of DM1, we constructed a DM1 cell culture model using a PC12 neuronal cell line and screened flavonoids that ameliorate this mRNA gain of function. The expanded 250 CTG repeat was subcloned into the 3'-untranslated region of the luciferase gene yielding a stable transformant of PC12 (CTG-250). The cytotoxicity of CTG-250 was evaluated by intracellular LDH activity, and the cis-effect by luciferase activity. To find agents that alter CTG-250 toxic effects, 235 bioflavonoids were screened. An increased cis-effect and cytotoxicity were found when CTG-250 was treated with nerve growth factor to induce differentiation. Western blotting with anti-caspase-3 antibody suggested that cell death was caused by apoptosis. Screening analysis confirmed that a flavone (toringin), an isoflavones (genistein and formononetin), a flavanone (isosakuranetin), and DHEA-S prevent both the cytotoxicity and cis-effect of CTG-250 and that a flavanone (naringenin), isoflavone (ononin), and xanthylatin strongly inhibit the cis-effect of CTG repeats. In conclusion, we found that this neuronal cell line, which expresses the CUG repeat-bearing mRNA, showed cis-effects through the reporter gene and neuronal death after cell differentiation in vitro. However, some flavonoids and DHEA-S inhibit both the cis-effect and cytotoxicity, indicating that their chemical structures work to ameliorate both these toxic effects. This system makes it easy to evaluate the toxic effects of expanded CTG repeats and therefore should be useful for screening other DM1 treatments for their efficacies.