Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Scn8a encodes an abundant, widely distributed voltage-gated sodium channel found throughout the central and peripheral nervous systems. Mice with different mutant alleles of Scn8a provide models of the movement disorders ataxia, dystonia, tremor and progressive paralysis. We previously reported that the phenotype of the hypomorphic allele of Scn8a, medJ, is dependent upon an unlinked modifier locus, Scnm1. Strain C57BL/6J carries a sensitive allele of the modifier locus that results in juvenile lethality. We now provide evidence that the modifier acts on the splicing efficiency of the mutant splice donor site. Mutant mice display either 90% or 95% reduction in the proportion of correctly spliced mRNA, depending on modifier genotype. The abundance of the channel protein, Na(v)1.6, is also reduced by an order of magnitude in medJ mice, resulting in delayed maturation of nodes of Ranvier, slowed nerve conduction velocity, reduced muscle mass and reduction of brain metabolic activity. medJ mice provide a model for the physiological effects of sodium channel deficiency and the molecular mechanism of bigenic disease.
Hum Mol Genet 2002 Oct 15
PMID:Molecular and pathological effects of a modifier gene on deficiency of the sodium channel Scn8a (Na(v)1.6). 1237 66

Episodic ataxia type 2 (EA2) has been reported to result from mutations in the CACNA1A gene, located on chromosome 19p13. We describe a family with episodic ataxia, clinically indistinguishable from EA2, that was not caused by CACNA1A gene mutation. The proband is an 11-year-old boy, who has had 6 cerebellar ataxic attacks since 8 years of age. His attacks occurred almost monthly, lasting for 2 to 3 days. He was treated successfully with acetazolamide. His identical twin, mother and grandmother developed ataxic attacks at age 10, 34, and 50, respectively. The symptoms in his grandmother improved gradually without medication. His mother and identical twin took acetazolamide with a good response. We examined the CACNA1A gene for this family but did not detect any mutations. Furthermore, there was no evidence of genetic linkage between the CACNA1A gene and the symptomatic patients in this family. This suggests that the cause of EA2 can be heterogeneous, that is, defects of genes other than CACNA1A might be the cause of EA2.
Int J Mol Med 2003 Feb
PMID:A family of episodic ataxia type 2: no evidence of genetic linkage to the CACNA1A gene. 1252 75

Aceruloplasminemia is characterized by iron accumulation in the brain as well as in visceral organs, due to the absence of ceruloplasmin ferroxidase activity. The neurological symptoms, which include involuntary movements, ataxia, and dementia, reflect the sites of iron deposition. The unique involvement of the central nervous system distinguishes aceruloplasminemia from other inherited and acquired iron storage disorders. Excess iron functions as a potent catalyst of biologic oxidation. An increased iron concentration was associated with increased lipid peroxidation in the brains of three aceruloplasminemia patients. Positron emission tomography showed brain glucose and oxygen hypometabolism. Enzyme activities in the mitochondrial respiratory chain of the basal ganglia were reduced to about 50 and 43%, respectively, for complexes I and IV. Those of the cerebral and cerebellar cortices also were decreased approximately 62 and 65%. These findings suggest that iron-mediated free radicals may contribute to neuronal cell damage through increased lipid peroxidation and the impairment of mitochondrial energy metabolism in aceruloplasminemia brains.
Blood Cells Mol Dis
PMID:Increased lipid peroxidation and mitochondrial dysfunction in aceruloplasminemia brains. 1254 32

A number of human hereditary diseases have been associated with the instability of DNA repeats in the genome. Recently, spinocerebellar ataxia type 10 has been associated with expansion of the pentanucleotide repeat (ATTCT)(n).(AGAAT)(n) from a normal range of ten to 22 to as many as 4500 copies. The structural properties of this repeat cloned in circular plasmids were studied by a variety of methods. Two-dimensional gel electrophoresis and atomic force microscopy detected local DNA unpairing in supercoiled plasmids. Chemical probing analysis indicated that, at moderate superhelical densities, the (ATTCT)(n).(AGAAT)(n) repeat forms an unpaired region, which further extends into adjacent A+T-rich flanking sequences at higher superhelical densities. The superhelical energy required to initiate duplex unpairing is essentially length-independent from eight to 46 repeats. In plasmids containing five repeats, minimal unpairing of (ATTCT)(5).(AGAAT)(5) occurred while 2D gel analysis and chemical probing indicate greater unpairing in A+T-rich sequences in other regions of the plasmid. The observed experimental results are consistent with a statistical mechanical, computational analysis of these supercoiled plasmids. For plasmids containing 29 repeats, which is just above the normal human size range, flanked by an A+T-rich sequence, atomic force microscopy detected the formation of a locally condensed structure at high superhelical densities. However, even at high superhelical densities, DNA strands within the presumably compact A+T-rich region were accessible to small chemicals and oligonucleotide hybridization. Thus, DNA strands in this "collapsed structure" remain unpaired and accessible for interaction with other molecules. The unpaired DNA structure functioned as an aberrant replication origin, in that it supported complete plasmid replication in a HeLa cell extract. A model is proposed in which unscheduled or aberrant DNA replication is a critical step in the expansion mutation.
J Mol Biol 2003 Feb 28
PMID:Unpaired structures in SCA10 (ATTCT)n.(AGAAT)n repeats. 1258 56

A body of experimental evidence indicates that transcription and/or mRNA processing factors interacting with the polyglutamine disease gene products play crucial roles in the pathology. PQBP-1 is one of these factors and it has been shown to interact with the spinocerebellar ataxia type-1 (SCA1) disease gene product, ataxin-1. Our previous data suggested that relatively high expression of PQBP-1 in the cerebellum might explain the selective neuronal degeneration of SCA1. To further test whether PQBP-1 expression level regulates neuronal death, we generated transgenic mice of human PQBP-1 driven by a regulatory element for ubiquitous gene expression. The mice showed a late-onset and gradually progressive motor neuron disease-like phenotype, which might be related to neurogenic muscular atrophy observed in SCA1 patients. Ataxia could not be discriminated from predominant progressive weakness. Pathological examinations of the transgenic mice revealed loss of Purkinje and granular cells in the cerebellum as well as that of spinal motor neurons, corresponding to the pathology of human SCA1. These findings show that excessive action of PQBP-1 causes neuronal dysfunction and support PQBP-1 being involved in the pathology of SCA1.
Hum Mol Genet 2003 Apr 01
PMID:PQBP-1 transgenic mice show a late-onset motor neuron disease-like phenotype. 1265 67

Recent studies have reported that alleles in the premutation range in the FMR1 gene in males result in increased FMR1 mRNA levels and at the same time mildly reduced FMR1 protein levels. Some elderly males with premutations exhibit an unique neurodegenerative syndrome characterized by progressive intention tremor and ataxia. We describe neurohistological, biochemical and molecular studies of the brains of mice with an expanded CGG repeat and report elevated Fmr1 mRNA levels and intranuclear inclusions with ubiquitin, Hsp40 and the 20S catalytic core complex of the proteasome as constituents. An increase was observed of both the number and the size of the inclusions during the course of life, which correlates with the progressive character of the cerebellar tremor/ataxia syndrome in humans. The observations in expanded-repeat mice support a direct role of the Fmr1 gene, by either CGG expansion per se or by mRNA level, in the formation of the inclusions and suggest a correlation between the presence of intranuclear inclusions in distinct regions of the brain and the clinical features in symptomatic premutation carriers. This mouse model will facilitate the possibilities to perform studies at the molecular level from onset of symptoms until the final stage of the disease.
Hum Mol Genet 2003 May 01
PMID:The FMR1 CGG repeat mouse displays ubiquitin-positive intranuclear neuronal inclusions; implications for the cerebellar tremor/ataxia syndrome. 1270 Jan 64

Dorsal root ganglion (DRG) neurons project their axons to specific target layers in the gray matter of the spinal cord, according to their sensory modality (Neuron 30 (2001), 707; Cell 101 (2000), 485; Neuron 31 (2001), 59; J. Comp. Neurol. 380 (1997), 215; Sensory Neurons, Oxford Univ. Press, New York, 1992, p. 131). Expression of runt-related Runx/AML genes (Mech. Dev. 109 (2001), 413) on subtypes of DRG neurons suggests their involvement in lamina-specific afferent differentiation and maturation. Here we show that Runx3-/- mice display severe limb ataxia and abnormal posture and that most of them die shortly after birth. They show that proprioceptive afferent axons fail to reach the ventral horn and have a smaller dorsal funiculus in their spinal cords. Despite the strong resemblance of this phenotype to that of knockout mice deficient in neurotrophin-3 (NT-3) (Cell 77 (1994), 503; Nature 369 (1994), 658) and its receptor, trkC, (Nature 368 (1994), 249), which show proprioceptive afferent loss through selective neuronal cell death, Runx3-/- mice maintain normal number of TrkC/trkC positive DRG neurons throughout development. Our results suggest that Runx3 controls the target-specific axon pathfinding of trkC-expressing DRG neurons in the spinal cord.
Blood Cells Mol Dis
PMID:Runx3 is essential for the target-specific axon pathfinding of trkc-expressing dorsal root ganglion neurons. 1273 77

The RUNX transcription factors are key regulators of lineage specific gene expression in developmental pathways. The mammalian RUNX genes arose early in evolution and maintained extensive structural similarities. Sequence analysis suggested that RUNX3 is the most ancient of the three mammalian genes, consistent with its role in neurogenesis of the monosynaptic reflex arc, the simplest neuronal response circuit, found in Cnidarians, the most primitive animals. All RUNX proteins bind to the same DNA motif and act as activators or repressors of transcription through recruitment of common transcriptional modulators. Nevertheless, analysis of Runx1 and Runx3 expression during embryogenesis revealed that their function is not redundant. In adults both Runx1 and Runx3 are highly expressed in the hematopoietic system. At early embryonic stages we found strong Runx3 expression in dorsal root ganglia neurons, confined to TrkC sensory neurons. In the absence of Runx3, knockout mice develop severe ataxia due to the early death of the TrkC neurons. Other phenotypic defects of Runx3 KO mice including abnormalities in thymopoiesis are also being investigated.
Blood Cells Mol Dis
PMID:Phylogenesis and regulated expression of the RUNT domain transcription factors RUNX1 and RUNX3. 1273 78

Nova is a neuron-specific RNA binding protein targeted in patients with the autoimmune disorder paraneoplastic opsoclonus-myoclonus ataxia, which is characterized by failure of inhibition of brainstem and spinal motor systems. Here, we have biochemically confirmed the observation that splicing regulation of the inhibitory GABA(A) receptor gamma2 (GABA(A)Rgamma2) subunit pre-mRNA exon E9 is disrupted in mice lacking Nova-1. To elucidate the mechanism by which Nova-1 regulates GABA(A)Rgamma2 alternative splicing, we systematically screened minigenes derived from the GABA(A)Rgamma2 and human beta-globin genes for their ability to support Nova-dependent splicing in transient transfection assays. These studies demonstrate that Nova-1 acts directly on GABA(A)Rgamma2 pre-mRNA to regulate E9 splicing and identify an intronic region that is necessary and sufficient for Nova-dependent enhancement of exon inclusion, which we term the NISE (Nova-dependent intronic splicing enhancer) element. The NISE element (located 80 nucleotides upstream of the splice acceptor site of the downstream exon E10) is composed of repeats of the sequence YCAY, consistent with previous studies of the mechanism by which Nova binds RNA. Mutation of these repeats abolishes binding of Nova-1 to the RNA in vitro and Nova-dependent splicing regulation in vivo. These data provide a molecular basis for understanding Nova regulation of GABA(A)Rgamma2 alternative splicing and suggest that general dysregulation of Nova's splicing enhancer function may underlie the neurologic defects seen in Nova's absence.
Mol Cell Biol 2003 Jul
PMID:Nova regulates GABA(A) receptor gamma2 alternative splicing via a distal downstream UCAU-rich intronic splicing enhancer. 1280 7

The small-conductance calcium-activated K(+) channel SK3 (SKCa3/KCNN3) regulates electrical excitability and neurotransmitter release in monoaminergic neurons, and has been implicated in schizophrenia, ataxia and anorexia nervosa. We have identified a novel SK3 transcript, SK3-1B that utilizes an alternative first exon (exon 1B), but is otherwise identical to SK3. SK3-1B, mRNA is widely distributed in human tissues and is present at 20-60% of SK3 in the brain. The SK3-1B protein lacks the N-terminus and first transmembrane segment, and begins eight residues upstream of the second transmembrane segment. When expressed alone, SK3-1B did not produce functional channels, but selectively suppressed endogenous SK3 currents in the pheochromocytoma cell line, PC12, in a dominant-negative fashion. This dominant inhibitory effect extended to other members of the SK subfamily, but not to voltage-gated K(+) channels, and appears to be due to intracellular trapping of endogenous SK channels. The effect of SK3-1B expression is very similar to that produced by expression of the rare SK3 truncation allele, SK3-Delta, found in a patient with schizophrenia. Regulation of SK3 and SK3-1B levels may provide a potent mechanism to titrate neuronal firing rates and neurotransmitter release in monoaminergic neurons, and alterations in the relative abundance of these proteins could contribute to abnormal neuronal excitability, and to the pathogenesis of schizophrenia.
Mol Psychiatry 2003 May
PMID:Novel truncated isoform of SK3 potassium channel is a potent dominant-negative regulator of SK currents: implications in schizophrenia. 1280 32


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