Expression of Disrupted-In-Schizophrenia-1, a schizophrenia-associated gene, is prominent in the mouse hippocampus throughout brain development.

DISC1 (Disrupted-In-Schizophrenia 1) has been associated with schizophrenia in multiple genetic studies. Studies from our laboratory have shown that Disc1, the mouse ortholog of DISC1, is highly expressed in the dentate gyrus of the hippocampus in the adult mouse brain. Because developmental dysfunction of the hippocampus is thought to play a major role in schizophrenia pathogenesis, and the dentate gyrus is a major locus for adult neurogenesis in the mouse, we investigated Disc1 expression during mouse brain development. Strikingly, Disc1 is strongly expressed in the hippocampus during all stages of hippocampal development, from embryonic day 14 through adulthood. Disc1 mRNA was detected in the dentate gyrus at all stages in which this structure was identifiable, as well as in the cornu ammonis (CA) fields of the hippocampus, the subiculum and adjacent entorhinal cortex, and the developing cerebral neocortex, hypothalamus, and olfactory bulbs, all of which also express Disc1 in the adult mouse brain. In addition, Disc1 mRNA was seen in regions of the developing mouse brain which do not express Disc1 during adulthood, regions including the bed nucleus of the stria terminalis, reticular thalamic nucleus and reuniens thalamic nucleus. These results demonstrate that Disc1 marks the hippocampus from its earliest stages, and suggest that developmental Disc1 dysfunction may lead to defects in hippocampal function that are associated with schizophrenia.

The murine cysteinyl leukotriene 2 (CysLT2) receptor. cDNA and genomic cloning, alternative splicing, and in vitro characterization.

Two classes of cysteinyl leukotriene receptor, CysLT(1) and CysLT(2), have been identified and pharmacologically characterized in human tissues. Although the CysLT(1) receptor mediates the proinflammatory effects of leukotrienes in human asthma, the physiological roles of CysLT(2) receptor are not defined, and a suitable mouse model would be useful in delineating function. We report here the molecular cloning and characterization of the mouse CysLT(2) receptor (mCysLT(2)R) from heart tissue. mCysLT(2)R cDNA encodes a protein of 309 amino acids, truncated at both ends compared with the human ortholog (hCysLT(2)R). The gene resides on the central region of mouse chromosome 14 and is composed of 6 exons with the entire coding region located in the last exon. Two 5'-untranslated region splice variants were identified with the short form lacking exon 3 as the predominant transcript. Although the overall expression of mCysLT(2)R is very low, the highest expression was detected in spleen, thymus, and adrenal gland by ribonuclease protection assay, and discrete sites of expression in heart were observed by in situ hybridization. Intracellular calcium mobilization in response to cysteinyl leukotriene administration was detected in human embryonic kidney 293T cells transfected with recombinant mCysLT(2)R with a rank order of potency leukotriene C(4)(LTC(4) ) = LTD(4)>>LTE(4). [(3)H]LTD(4) binding to membranes expressing mCysLT(2)R could be effectively competed by LTC(4) and LTD(4) and only partially inhibited by LTE(4) and BAYu9773. The identification of mCysLT(2)R will be useful for establishing CysLT(2)R-deficient mice and determining novel leukotriene functions.

Cloning and functional expression of two families of beta-subunits of the large conductance calcium-activated K+ channel.

We report here a characterization of two families of calcium-activated K(+) channel beta-subunits, beta2 and beta3, which are encoded by distinct genes that map to 3q26.2-27. A single beta2 family member and four alternatively spliced variants of beta3 were investigated. These subunits have predicted molecular masses of 27. 1-31.6 kDa, share approximately 30-44% amino acid identity with beta1, and exhibit distinct but overlapping expression patterns. Coexpression of the beta2 or beta3a-c subunits with a BK alpha-subunit altered the functional properties of the current expressed by the alpha-subunit alone. The beta2 subunit rapidly and completely inactivated the current and shifted the voltage dependence for activation to more polarized membrane potentials. In contrast, coexpression of the beta3a-c subunits resulted in only partial inactivation of the current, and the beta3b subunit conferred an apparent inward rectification. Furthermore, unlike the beta1 and beta2 subunits, none of the beta3 subunits increased channel sensitivity to calcium or voltage. The tissue-specific expression of these beta-subunits may allow for the assembly of a large number of distinct BK channels in vivo, contributing to the functional diversity of native BK currents.

Identification of the gene responsible for Best macular dystrophy.

Best macular dystrophy (BMD), also known as vitelliform macular dystrophy (VMD2; OMIM 153700), is an autosomal dominant form of macular degeneration characterized by an abnormal accumulation of lipofuscin within and beneath the retinal pigment epithelium cells. In pursuit of the disease gene, we limited the minimum genetic region by recombination breakpoint analysis and mapped to this region a novel retina-specific gene (VMD2). Genetic mapping data, identification of five independent disease-specific mutations and expression studies provide evidence that mutations within the candidate gene are a cause of BMD. The 3' UTR of the candidate gene contains a region of antisense complementarity to the 3' UTR of the ferritin heavy-chain gene (FTH1), indicating the possibility of antisense interaction between VMD2 and FTH1 transcripts.