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M H Meisler

Publications and source records attributed to M H Meisler.

At least 37 records · Page 2Linked to original sources
PubMed1999

Coding sequence, genomic organization, and conserved chromosomal localization of the mouse gene Scn11a encoding the sodium channel NaN.

Previous studies have shown that sodium channel alpha-subunit NaN is preferentially expressed in small-diameter sensory neurons of dorsal root ganglia and trigeminal ganglia. These neurons include high-threshold nociceptors that are involved in transduction of pain associated with tissue and nerve injury. In this study, we show that mouse NaN is a 1765-amino-acid peptide that is predicted to produce a current that is resistant to tetrodotoxin (TTX-R). Mouse and rat NaN are 80 and 89% identical at the nucleotide and amino acid levels, respectively. The Scn11a gene encoding this cDNA is organized into 24 exons. Unlike some alpha-subunits, Scn11a does not have an alternative exon 5 in domain I. Introns of the U2 and U12 spliceosome types are present at conserved positions relative to other members of this family. Scn11a is located on mouse chromosome 9, close to the two other TTX-R sodium channel genes, Scn5a and Scn10a. The human gene, SCN11A, was mapped to the conserved linkage group on chromosome 3p21-p24, close to human SCN5A and SCN10A. The colocalization of the three sodium channel genes supports a common lineage of the TTX-R sodium channels.

Amino Acid Sequence↗
PubMed1999

Dystonia associated with mutation of the neuronal sodium channel Scn8a and identification of the modifier locus Scnm1 on mouse chromosome 3.

The mouse mutant medJ contains a splice site mutation in the neuronal sodium channel Scn8a that results in a very low level of expression. On a C57BL/6J genetic background, medJ homozygotes exhibit progressive paralysis and juvenile lethality. The C3H genetic background has an ameliorating effect, producing viable adults with a novel dystonic phenotype. The dystonic mice exhibit movement-induced, sustained abnormal postures of the trunk and limbs. A dominant modifier locus responsible for the difference between strains was mapped to a 4.5 +/- 1.3 cM interval on mouse chromosome 3. Our findings establish a role for ion channels in dystonia and demonstrate the impact of genetic background on its severity and progression. This new model suggests that SCN8A on chromosome 12q13 and SCNM1 on chromosome 1p21-1q21 may contribute to human inherited dystonia.

Animals↗
PubMed1999

Comparative sequence of human and mouse BAC clones from the mnd2 region of chromosome 2p13.

The mnd2 mutation on mouse chromosome 6 produces a progressive neuromuscular disorder. To determine the gene content of the 400-kb mnd2 nonrecombinant region, we sequenced 108 kb of mouse genomic DNA and 92 kb of human genomic sequence from the corresponding region of chromosome 2p13.3. Three genes with the indicated sizes and intergenic distances were identified: D6Mm5e (>/=81 kb)-787 bp-DOK (2 kb)-845 bp-LOR2 (>/=6 kb). D6Mm5e is expressed in many tissues at very low abundance and the predicted 526-residue protein contains no known functional domains. DOK encodes the p62(dok) rasGAP binding protein involved in signal transduction. LOR2 encodes a novel lysyl oxidase-related protein of 757 amino acid residues. We describe a simple search protocol for identification of conserved internal exons in genomic sequence. Evolutionary conservation proved to be a useful criterion for distinguishing between authentic exons and artifactual products obtained by exon amplification, RT-PCR, and 5' RACE. Conserved noncoding sequence elements longer than 80 bp with >/=75% nucleotide sequence identity comprise approximately 1% of the genomic sequence in this region. Comparative analysis of this human and mouse genomic DNA sequence was an efficient method for gene identification and is independent of developmental stage or quantitative level of gene expression. [The sequence data described in this paper have been submitted to the GenBank data library under the following accession numbers: AC003061, mouse BAC clone 245c12; AC003065, human BAC clone h173(E10); AF053368, mouse Lor2 cDNA; AF084363, 108-kb contig from mouse BAC 245c12; AF084364, mouse D6Mm5e cDNA.]

Amino Acid Sequence↗
PubMed1998

Exon organization, coding sequence, physical mapping, and polymorphic intragenic markers for the human neuronal sodium channel gene SCN8A.

The voltage-gated sodium channel SCN8A is associated with inherited neurological disorders in the mouse that include ataxia, dystonia, severe muscle weakness, and paralysis. We report the complete coding sequence and exon organization of the human SCN8A gene. The predicted 1980 amino acid residues are distributed among 28 exons, including two pairs of alternatively spliced exons. The SCN8A protein is evolutionarily conserved, with 98.5% amino acid sequence identity between human and mouse. Consensus sites for phosphorylation of serine/threonine and tyrosine residues are present in cyoplasmic loop domains. The polymorphic (CA)n microsatellite marker D12S2211, with PIC = 0.68, was isolated from intron 10C of SCN8A. Single nucleotide polymorphisms in intron 19 and exon 22 were also identified. We localized SCN8A to chromosome band 12q13.1 by physical mapping on a YAC contig. The cDNA clone CSC-1 was reported by others to be a cardiac-specific sodium channel, but sequence comparison demonstrates that it is derived from exon 24 of human SCN8A. The genetic information described here will be useful in evaluating SCN8A as a candidate gene for human neurological disease.

Alternative Splicing↗
PubMed1998

High-resolution genetic, physical, and transcript map of the mnd2 region of mouse chromosome 6.

The autosomal recessive mutation mnd2 is responsible for a lethal neuromuscular wasting disorder in the mouse. A high-resolution genetic map of the mnd2 region of mouse chromosome 6 was generated by analysis of 1147 F2 offspring from an intersubspecific cross between strains C57BL/6J-mnd2/+ and CAST/Ei. The results localize mnd2 to the 0.2-cM interval between D6Mit164 and D6Mit128. A contig of overlapping YAC, BAC, and P1 clones spanning the nonrecombinant interval was constructed. One novel gene isolated from the contig, D6Mm3e, is a new member of the WD repeat gene family. The observed gene order for the five positional candidate genes previously mapped to the region and five newly isolated genes is centromere-Hexokinase II-D6Mm5e-p62 Dok-Aup1-Rhotekin, D6Mm3e-Dynactin 1-Smooth muscle gamma actin-D6Mm4e-beta-adducin-telomere. Seven of these genes are located within the 400-kb nonrecombinant interval for mnd2. Comparison between wildtype and mutant failed to detect any differences in mRNA size, abundance, or coding sequence for these seven genes. The genes described here are positional candidates for the Parkinson disease susceptibility locus PARK3 that was recently mapped to the corresponding region of human chromosome band 2p13.1.

Amino Acid Sequence↗
PubMed1998

Functional analysis of the mouse Scn8a sodium channel.

The mouse Scn8a sodium channel and its ortholog Na6 in the rat are abundantly expressed in the CNS. Mutations in mouse Scn8a result in neurological disorders, including paralysis, ataxia, and dystonia. In addition, Scn8a has been observed to mediate unique persistent and resurgent currents in cerebellar Purkinje cells (Raman et al., 1997). To examine the functional characteristics of this channel, we constructed a full-length cDNA clone encoding the mouse Scn8a sodium channel and expressed it in Xenopus oocytes. The electrophysiological properties of the Scn8a channels were compared with those of the Rat1 and Rat2 sodium channels. Scn8a channels were sensitive to tetrodotoxin at a level comparable to that of Rat1 or Rat2. Scn8a channels inactivated more rapidly and showed differences in their voltage-dependent properties compared with Rat1 and Rat2 when only the alpha subunits were expressed. Coexpression of the beta1 and beta2 subunits modulated the properties of Scn8a channels, but to a lesser extent than for the Rat1 or Rat2 channels. Therefore, all three channels showed similar voltage dependence and inactivation kinetics in the presence of the beta subunits. Scn8a channels coexpressed with the beta subunits exhibited a persistent current that became larger with increasing depolarization, which was not observed for either Rat1 or Rat2 channels. The unique persistent current observed for Scn8a channels is consistent with the hypothesis that this channel is responsible for distinct sodium conductances underlying repetitive firing of action potentials in Purkinje neurons.

Amino Acid Sequence↗
PubMed1998

The sodium channel Scn8a is the major contributor to the postnatal developmental increase of sodium current density in spinal motoneurons.

Sodium currents were recorded from motoneurons that were isolated from mice at postnatal days 0-8 (P0-P8) and maintained in culture for 12-24 hr. Motoneurons from normal mice exhibited a more than threefold increase in peak sodium current density from P0 to P8. For mice lacking a functional Scn8a sodium channel gene, motoneuronal sodium current density was comparable at P0 to that of normal mice but failed to increase from P0 to P8. The absence of Scn8a sodium channels is associated with the phenotype "motor end plate disease," which is characterized by a progressive neuromuscular failure and is fatal by 3-4 postnatal weeks. Thus, it appears that the development and function of mature motoneurons depends on the postnatal induction of Scn8a expression.

Animals↗
PubMed1998

Calcium channel beta 4 (CACNB4): human ortholog of the mouse epilepsy gene lethargic.

The mouse neurological mutant lethargic (lh) is characterized by ataxia, focal myoclonus, and absence epilepsy due to a loss-of-function mutation in the beta4 subunit of the voltage-gated calcium channel. To evaluate the role of this channel subunit in human neurological disease, we determined the chromosomal location and intron/exon structure of the human CACNB4 gene. The 1560-bp open reading frame of the CACNB4 cDNA predicts a 58-kDa protein with an amino acid sequence that is 99% identical to the rat protein. The 13 coding exons of CACNB4 span >55 kb of genomic DNA. Human cerebellar RNA contains one major CACNB4 transcript that is 9 kb in length. Expression of CACNB4 was detected in cerebellum, kidney, testis, retina, lymphoblasts, and circulating lymphocytes. Retinal transcripts were localized by in situ hybridization to ganglion cells and the inner nuclear layer. Analysis of the GeneBridge 4 radiation hybrid mapping panel localized CACNB4 to position 791 cR on human chromosome 2, in a conserved linkage group on human 2q22-q31 and mouse chromosome 2. We localized CACNB4 to the 1.3-Mb YAC clone 952F10 in Whitehead contig WC861, along with the polymorphic markers D2S2236 and D2S2299. The chromosomal linkage of three of the four beta subunit genes to homeobox gene clusters associates the evolutionary origin of the beta gene family with the events that generated the four HOX clusters early in vertebrate evolution.

Alternative Splicing↗
PubMed1998

Marshall syndrome associated with a splicing defect at the COL11A1 locus.

Marshall syndrome is a rare, autosomal dominant skeletal dysplasia that is phenotypically similar to the more common disorder Stickler syndrome. For a large kindred with Marshall syndrome, we demonstrate a splice-donor-site mutation in the COL11A1 gene that cosegregates with the phenotype. The G+1-->A transition causes in-frame skipping of a 54-bp exon and deletes amino acids 726-743 from the major triple-helical domain of the alpha1(XI) collagen polypeptide. The data support the hypothesis that the alpha1(XI) collagen polypeptide has an important role in skeletal morphogenesis that extends beyond its contribution to structural integrity of the cartilage extracellular matrix. Our results also demonstrate allelism of Marshall syndrome with the subset of Stickler syndrome families associated with COL11A1 mutations.

Chromosomes, Human, Pair 1↗
PubMed1997

Alternative splicing of the sodium channel SCN8A predicts a truncated two-domain protein in fetal brain and non-neuronal cells.

The voltage-gated sodium channel alpha subunit SCN8A is one of the most abundant sodium channels in neurons from brain and spinal cord. We have identified two alternatively spliced exons, 18N and 18A, that encode transmembrane segments S3 and S4 in domain III. Exon 18N is expressed in fetal brain and non-neuronal tissues. Transcripts with exon 18N have a conserved in-frame stop codon that predicts the synthesis of a truncated, two-domain protein similar to the fetal form of the muscle calcium channel. The proportion of transcripts containing exon 18N is highest in mouse fetal brain between E12.5 and P1.5; at later ages transcripts containing exon 18A predominate. This developmental program is recapitulated in P19 cells during retinoic acid-induced neuronal differentiation. Non-neuronal tissues contain a low level of SCN8A transcripts containing exon 18N. SCN8A thus provides a new model of differentiation specific splicing. Genomic analysis of SCN8A from human, mouse, and fish demonstrated a conserved structure in which exon 18N is located 300-500 bp upstream of exon 18A. Duplication of exon 18 thus preceded the divergence of fish and mammals. The genomic organization, developmental regulation, and coding content of exons 18N and 18A closely resemble the previously described alternate exons 5N and 5A of the neuronal sodium channel genes. Our proposal that the evolutionary origin of exons 18N and 18A was by duplication of exons 5N and 5A is consistent with other evidence that the four-domain cation channels arose by two rounds of duplication from a single-domain ancestral channel.

Alternative Splicing↗
PubMed1997

Cooperation of Pax2 and Pax5 in midbrain and cerebellum development.

Midbrain and cerebellum development depends on an organizing center that is located at the midbrain-hindbrain junction of the vertebrate embryo. Expression of the two closely related transcription factors Pax2 and Pax5 overlaps spatially and temporally in this region of the developing central nervous system. To study a possible interaction of these transcription factors in midbrain and cerebellum patterning, we have generated Pax5, Krd double mutant mice. The transgene-induced Krd mutation corresponds to an approximately 7-centimorgan chromosome 19 deletion that eliminates the entire Pax2 locus. The heterozygous Krd mutation deleting one Pax2 allele had no effect on midbrain and cerebellum development. Moreover, only minor developmental defects were previously observed at the midline of the inferior colliculus and anterior cerebellum in mice that were homozygous for a targeted Pax5 mutation. Similar morphological alterations were observed in 80% of all compound heterozygous Pax5 (+/-) Krd (+/-) mice. However, in the remaining 20% of compound heterozygotes, the inferior colliculi were missing, and the vermis of the cerebellum was severely disrupted due to the failure of the cerebellar primordia to fuse at the midline. Inactivation of the second Pax5 allele in Pax5 (-/-) Krd (+/-) mice resulted in complete loss of the posterior midbrain and cerebellum, as the tissue originating from the midbrain-hindbrain boundary region was deleted in the embryo as early as day 9.5. On the basis of these data, we propose that the cooperation of Pax2 and Pax5 is essential for normal functioning of the organizing center at the midbrain-hindbrain junction.

Animals↗
PubMed1997

Mouse p150Glued (dynactin 1) cDNA sequence and evaluation as a candidate for the neuromuscular disease mutation mnd2.

p150Glued (Dynactin 1) is a component of the dynactin complex that is essential for retrograde axonal transport in neurons. The mouse p150Glued cDNA was isolated from mouse brain by RT-PCR. The complete sequence of the full length mouse cDNA was determined, including 19 bp of 5' UTR, 3843 bp of coding sequence, and 162 bp of 3' UTR. The predicted protein has a molecular mass of 142 kDa and exhibits 95% amino acid sequence identity to the predicted amino acid sequence of human p150Glued (DCTN1). The mouse Dctn1 gene was previously mapped in the central region of mouse chromosome 6, close to the neuromuscular disease gene mnd2. Northern blot analysis, complete sequencing of the cDNA, Western blot, and functional tests of the protein did not detect any abnormalities of p150Glued in mnd2 mice.

Amino Acid Sequence↗
PubMed1997

Mutation of the Ca2+ channel beta subunit gene Cchb4 is associated with ataxia and seizures in the lethargic (lh) mouse.

Ca2+ channel beta subunits regulate voltage-dependent calcium currents through direct interaction with alpha 1 subunits. The beta- and alpha 1-binding motifs are conserved, and all beta subunits can stimulate current amplitude, voltage dependence, and kinetics when coexpressed with various alpha 1 subunits. We used a positional candidate approach to determine that the ataxia and seizures in the lethargic (lh) mouse arise from mutation of the beta-subunit gene Cchb4 on mouse chromosome 2. A four-nucleotide insertion into a splice donor site results in exon skipping, translational frameshift, and protein truncation with loss of the alpha 1-binding site. The lethargic phenotype is the first example of a mammalian neurological disease caused by an inherited defect in a non-pore-forming subunit of a voltage-gated ion channel.

Amino Acid Sequence↗