Identification of loss-of-function mutations of SLC35D1 in patients with Schneckenbecken dysplasia, but not with other severe spondylodysplastic dysplasias group diseases

BACKGROUND

Schneckenbecken dysplasia (SBD) is an autosomal recessive lethal skeletal dysplasia that is classified into the severe spondylodysplastic dysplasias (SSDD) group in the international nosology for skeletal dysplasias. The radiological hallmark of SBD is the snail-like configuration of the hypoplastic iliac bone. SLC35D1 (solute carrier-35D1) is a nucleotide-sugar transporter involved in proteoglycan synthesis. Recently, based on human and mouse genetic studies, we showed that loss-of-function mutations of the SLC35D1 gene (SLC35D1) cause SBD.

OBJECT

To explore further the range of SLC35D1 mutations in SBD and elucidate whether SLC35D1 mutations cause other skeletal dysplasias that belong to the SSDD group.

METHODS AND RESULTS

We searched for SLC35D1 mutations in five families with SBD and 15 patients with other SSDD group diseases, including achodrogenesis type 1A, spondylometaphyseal dysplasia Sedaghatian type and fibrochondrogenesis. We identified four novel mutations, c.319C>T (p.R107X), IVS4+3A>G, a 4959-bp deletion causing the removal of exon 7 (p.R178fsX15), and c.193A>C (p. T65P), in three SBD families. Exon trapping assay showed IVS4+3A>G caused skipping of exon 4 and a frameshift (p.L109fsX18). Yeast complementation assay showed the T65P mutant protein lost the transporter activity of nucleotide sugars. Therefore, all these mutations result in loss of function. No SLC35D1 mutations were identified in all patients with other SSDD group diseases.

CONCLUSION

Our findings suggest that SLC35D1 loss-of-function mutations result consistently in SBD and are exclusive to SBD.

Developmentally regulated Ca2+-dependent activator protein for secretion 2 (CAPS2) is involved in BDNF secretion and is associated with autism susceptibility

The postnatal development of the cerebellum is accomplished via a series of cytogenetic and morphogenetic events encoded in the genome. To decipher the underlying genetic basis of these events we have systematized the spatio-temporal gene expression profiles during mouse cerebellar development in the Cerebellar Development Transcriptome Database (CDT-DB). Using the CDT-DB, Ca(2+)-dependent activator protein for secretion 2 (CAPS2 or CADPS2) was identified as a developmentally regulated gene that is predominantly expressed in cerebellar granule cells (GCs) with an expression peak around the first or second postnatal week. CAPS2 protein is concentrated in parallel fiber (PF) terminals and is associated with secretory vesicles containing brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3). CAPS2 enhances release of BDNF and NT-3, both of which are essential for normal cerebellar development. CAPS2-deficient (CAPS2(-/-)) mice show reduced secretion of BDNF and NT-3; consequently, the cerebella of these mice exhibit developmental deficits, such as delayed development and increased cell death in GCs, fewer branched dendrites on Purkinje cells (PCs), and loss of the intercrural fissure. The PF-PC synapses have aberrant cytoarchitectures and electrophysiological properties. These abnormal cellular and morphological phenotypes are more severe around the cerebellar vermis, in which hypoplasia has been reported in autism patients. Moreover, CAPS2(-/-) mice had fewer cortical and hippocampal parvalbumin-positive interneurons and some autistic-like behavioral phenotypes. In the CAPS2 genes of some autistic patients an aberrant splicing variant and non-synonymous SNPs have been identified. These recent studies implicate CAPS2 in autism susceptibility. Therefore, CAPS2(-/-) mice will be a useful model animal in which to study aspects of the neuropathology and behaviors characteristic of developmental disorders.

A fuzzy analytic network process for multi-criteria evaluation of contaminated site remedial countermeasures

The Analytic Network Process (ANP) has been proposed to incorporate interdependence and feedback effect in the prioritization of remedial countermeasures using a hierarchical network decision model, but this approach seems to be incapable of capturing the vagueness and fuzziness during value judgment elicitation. The aim of this paper is to present an evaluation method using a fuzzy ANP (FANP) approach to address this shortcoming. Triangular fuzzy numbers (TFN) and their degree of fuzziness are used in the semantic scale as human judgment expressed in natural language is most often vague and fuzzy. The method employs the alpha-cuts, interval arithmetic and optimism index to transform the fuzzy comparative judgment matrix into set of crisp matrices, and then calculates the desired priorities using the eigenvector method. A numerical example, which was drawn from a real-life case study of an uncontrolled landfill in Japan, is presented to demonstrate the process. Results from the sensitivity analysis describe how the fuzziness in judgment could affect the solution robustness of the prioritization method. The proposed FANP approach therefore could effectively deal with the uncertain judgment inherent in the decision making process and derive the meaningful priorities explicitly from a complex decision structure in the evaluation of contaminated site remedial countermeasures.

Opalin, a transmembrane sialylglycoprotein located in the central nervous system myelin paranodal loop membrane

In contrast to compact myelin, the series of paranodal loops located in the outermost lateral region of myelin is non-compact; the intracellular space is filled by a continuous channel of cytoplasm, the extracellular surfaces between neighboring loops keep a definite distance, but the loop membranes have junctional specializations. Although the proteins that form compact myelin have been well studied, the protein components of paranodal loop membranes are not fully understood. This report describes the biochemical characterization and expression of Opalin as a novel membrane protein in paranodal loops. Mouse Opalin is composed of a short N-terminal extracellular domain (amino acid residues 1-30), a transmembrane domain (residues 31-53), and a long C-terminal intracellular domain (residues 54-143). Opalin is enriched in myelin of the central nervous system, but not that of the peripheral nervous system of mice. Enzymatic deglycosylation showed that myelin Opalin contained N- and O-glycans, and that the O-glycans, at least, had negatively charged sialic acids. We identified two N-glycan sites at Asn-6 and Asn-12 and an O-glycan site at Thr-14 in the extracellular domain. Site-directed mutations at the glycan sites impaired the cell surface localization of Opalin. In addition to the somata and processes of oligodendrocytes, Opalin immunoreactivity was observed in myelinated axons in a spiral fashion, and was concentrated in the paranodal loop region. Immunogold electron microscopy demonstrated that Opalin was localized at particular sites in the paranodal loop membrane. These results suggest a role for highly sialylglycosylated Opalin in an intermembranous function of the myelin paranodal loops in the central nervous system.

Sequential expression of Efhc1/myoclonin1 in choroid plexus and ependymal cell cilia

EFHC1 is a gene mutated in patients with idiopathic epilepsies, and encodes the myoclonin1 protein. We here report the distribution of myoclonin1 in mouse. Immunohistochemical analyses revealed that the myoclonin1 first appeared at the roof of hindbrain at embryonic day 10 (E10), and moved on to choroid plexus at E14. At E18, it moved to ventricle walls and disappeared from choroid plexus. From neonatal to adult stages, myoclonin1 was concentrated in the cilia of ependymal cells at ventricle walls. At adult stages, myoclonin1 expression was also observed at tracheal epithelial cilia in lung and at sperm flagella in testis. Specificities of these immunohistochemical signals were verified by using Efhc1-deficient mice as negative controls. Results of Efhc1 mRNA in situ hybridization were also consistent with the immunohistochemical observations. Our findings raise "choroid plexusopathy" or "ciliopathy" as intriguing candidate cascades for the molecular pathology of epilepsies caused by the EFHC1 mutations.

Very-KIND, a KIND domain containing RasGEF, controls dendrite growth by linking Ras small GTPases and MAP2

The regulation of cytoskeletal components in the dendritic shaft core is critical for dendrite elongation and branching. Here, we report that a brain-specific Ras guanine nucleotide exchange factor (RasGEF) carrying two kinase non-catalytic C-lobe domains (KINDs), very-KIND (v-KIND), regulates microtubule-associated protein 2 (MAP2). v-KIND is expressed in developing mouse brain, predominantly in the cerebellar granule cells. v-KIND not only activates Ras small GTPases via the C-terminal RasGEF domain, but also specifically binds to MAP2 via the second KIND domain (KIND2), leading to threonine phosphorylation of MAP2. v-KIND overexpression suppresses dendritic extension and branching of hippocampal neurons and cerebellar granule cells, whereas knockdown of endogenous v-KIND expression promotes dendrite growth. These findings suggest that v-KIND mediates a signaling pathway that links Ras and MAP2 to control dendrite growth.

The inositol 1,4,5-trisphosphate receptor

Inositol 1,4,5-trisphosphate (InsP3) is a second messenger that releases Ca2+ from its intracellular stores. The InsP3 receptor has been purified and its cDNA has been cloned. We have found that the InsP3 receptor is identical to P400 protein, first identified as a protein enriched in cerebellar Purkinje cells. We have generated an L-fibroblast cell transfectant that produces cDNA-derived InsP3 receptors. The protein displays high affinity and specificity for InsP3. InsP3 induces greater Ca2+ release from membrane vesicles from transfected cells than from those from control L-fibroblasts. After incorporation of the purified InsP3 receptor into lipid bilayers InsP3-induced Ca2+ currents were demonstrated. These results suggest that the InsP3 receptor is involved in physiological Ca2+ release. Immunogold labelling using monoclonal antibodies against the receptor showed that it is highly concentrated on the smooth-surfaced endoplasmic reticulum and slightly on the outer nuclear membrane and rough endoplasmic reticulum; no labelling of Golgi apparatus, mitochondria and plasmalemma was seen. Cross-linking experiments showed that the receptor forms a homotetramer. The approximately 650 N-terminal amino acids are highly conserved between mouse and Drosophila, and this region contains the critical sequences for InsP3 binding. We have investigated the heterogeneity of the InsP3 receptor using the polymerase chain reaction and have found novel subtypes of the mouse InsP3 receptor that are expressed in a tissue-specific and developmentally specific manner.

The role of brain-derived neurotrophic factor (BDNF)-induced XBP1 splicing during brain development

Accumulation of unfolded proteins in the endoplasmic reticulum initiates intracellular signaling termed the unfolded protein response (UPR). Although Xbp1 serves as a pivotal transcription factor for the UPR, the physiological role of UPR signaling and Xbp1 in the central nervous system remains to be elucidated. Here, we show that Xbp1 mRNA was highly expressed during neurodevelopment and activated Xbp1 protein was distributed throughout developing neurons, including neurites. The isolated neurite culture system and time-lapse imaging demonstrated that Xbp1 was activated in neurites in response to brain-derived neurotrophic factor (BDNF), followed by subsequent translocation of the active Xbp1 into the nucleus. BDNF-dependent neurite outgrowth was significantly attenuated in Xbp1(-/-) neurons. These findings suggest that BDNF initiates UPR signaling in neurites and that Xbp1, which is activated as part of the UPR, conveys the local information from neurites to the nucleus, contributing the neurite outgrowth.

Structural and functional analysis of the apoptosis-associated tyrosine kinase (AATYK) family

Apoptosis-associated tyrosine kinase (AATYK) is a protein kinase that is predominantly expressed in the nervous system and is involved in apoptosis and neurite growth of cerebellar granule cells. In this study, we cloned three new members of the mouse AATYK family, AATYK1B, AATYK2 and AATYK3. AATYK1B is a splicing variant of the previously reported AATYK1 (referred to as AATYK1A hereafter). In comparison with AATYK1A, these three AATYK members were characterized by having an extra N-terminal region that consists of a signal peptide-like sequence and a predicted transmembrane (TM) region, which is followed by a kinase domain and a long C-terminal domain. Both TM-containing AATYK isoforms (AATYK(+)TM: AATYK1B, 2, and 3) and TM-lacking isoform (AATYK(-)TM: AATYK1A) were recovered in membrane fractions, suggesting that AATYK(+)TM and AATYK(-)TM are transmembrane- and peripheral-membrane protein kinases, respectively. AATYK1A was recovered in the soluble fraction when the cells were treated with 2-bromo palmitate, suggesting that AATYK1A associates with membrane via palmitoylation. The kinase domain was highly conserved among all AATYK members and was shown to be catalytically active. Three AATYK family members were predominantly expressed in adult mouse brains with almost similar expression profiles: widespread distribution over the various brain regions, especially in the cerebellum and hippocampus, and up-regulated expression during development of the cerebellum. In cultured cerebellar granule cells, AATYK1 was abundantly localized in both soma and axons, AATYK2 distribution was restricted to soma, and AATYK3 was punctately present over the cells. AATYK1 was concentrated in the central domain of growth cones of dorsal root ganglion neurons. Our results indicate that AATYK family members are brain-dominant and membrane-associated kinases with slightly different distribution patterns in the developing and adult mouse brain, which may be involved in fine regulation of neuronal functions including neurite extension and apoptosis.

The Homer family proteins

The Homer family of adaptor proteins consists of three members in mammals, and homologs are also known in other animals but not elsewhere. They are predominantly localized at the postsynaptic density in mammalian neurons and act as adaptor proteins for many postsynaptic density proteins. As a result of alternative splicing each member has several variants, which are classified primarily into the long and short forms. The long Homer forms are constitutively expressed and consist of two major domains: the amino-terminal target-binding domain, which includes an Enabled/vasodilator-stimulated phosphoprotein (Ena/VASP) homology 1 (EVH1) domain, and the carboxy-terminal self-assembly domain containing a coiled-coil structure and leucine zipper motif. Multimers of long Homer proteins, coupled through their carboxy-terminal domains, are thought to form protein clusters with other postsynaptic density proteins, which are bound through the amino-terminal domains. Such Homer-mediated clustering probably regulates or facilitates signal transduction or cross-talk between target proteins. The short Homer forms lack the carboxy-terminal domain; they are expressed in an activity-dependent manner as immediate-early gene products, possibly disrupting Homer clusters by competitive binding to target proteins. Homer proteins are also involved in diverse non-neural physiological functions.

Localization and expression of group I metabotropic glutamate receptors in the mouse striatum, globus pallidus, and subthalamic nucleus: regulatory effects of MPTP treatment and constitutive Homer deletion

Group I metabotropic glutamate receptors (mGluRs), mGluR1 and mGluR5, regulate activity in the globus pallidus (GP) and subthalamic nucleus (STN). To test whether the localization of group I mGluRs is altered in parkinsonism, we used immunoelectron microscopy to analyze the subcellular and subsynaptic distribution of mGluR1a and mGluR5 in GP and STN of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice. Homer1 and Homer2 knock-out mice were used to assess the role of Homer in MPTP-induced redistribution of group I mGluRs. We also examined the effects of MPTP on the expression levels of group I mGluRs and Homer proteins in GP and striatum. MPTP treatment significantly reduced the expression levels of H1a and mGluR1a in striatum but not in GP. Although light microscopy did not reveal noticeable effects of MPTP treatment on the distribution of group I mGluRs and Homer proteins in GP and STN, specific changes in the ultrastructural localization of mGluR1a were found in MPTP-treated normal and Homer knock-out mice. An increase in the expression of presynaptic axonal and terminal mGluR1a labeling and an increased level of mGluR1a immunoreactivity in the postsynaptic specialization of putative GABAergic synapses were among the most significant effects induced by dopamine depletion. However, neither of these changes was found for mGluR5, which, in contrast, displayed complex regulatory alterations in its subsynaptic distribution in response to Homer deletion and MPTP lesion. Thus, nigrostriatal dopaminergic lesion and Homer deletion lead to changes in the trafficking of group I mGluRs in vivo that are specific to receptor subtypes and brain areas.

Nav1.1 localizes to axons of parvalbumin-positive inhibitory interneurons: a circuit basis for epileptic seizures in mice carrying an Scn1a gene mutation

Loss-of-function mutations in human SCN1A gene encoding Nav1.1 are associated with a severe epileptic disorder known as severe myoclonic epilepsy in infancy. Here, we generated and characterized a knock-in mouse line with a loss-of-function nonsense mutation in the Scn1a gene. Both homozygous and heterozygous knock-in mice developed epileptic seizures within the first postnatal month. Immunohistochemical analyses revealed that, in the developing neocortex, Nav1.1 was clustered predominantly at the axon initial segments of parvalbumin-positive (PV) interneurons. In heterozygous knock-in mice, trains of evoked action potentials in these fast-spiking, inhibitory cells exhibited pronounced spike amplitude decrement late in the burst. Our data indicate that Nav1.1 plays critical roles in the spike output from PV interneurons and, furthermore, that the specifically altered function of these inhibitory circuits may contribute to epileptic seizures in the mice.

An oligodendrocyte enhancer in a phylogenetically conserved intron region of the mammalian myelin gene Opalin

Opalin is a transmembrane protein detected specifically in mammalian oligodendrocytes. Opalin homologs are found only in mammals and not in the genome sequences of other animal classes. We first determined the nucleotide sequences of Opalin orthologs and their flanking regions derived from four prosimians, a group of primitive primates. A global comparison revealed that an evolutionarily conserved region exists in the first intron of Opalin. When the conserved domain was assayed for its enhancer activity in transgenic mice, oligodendrocyte-directed expression was observed. In an oligodendroglial cell line, Oli-neu, the conserved domain showed oligodendrocyte-directed expression. The conserved domain is composed of eight subdomains, some of which contain binding sites for Myt1 and cAMP-response element binding protein (CREB). Deletion analysis and cotransfection experiments revealed that the subdomains have critical roles in Opalin gene expression. Over-expression of Myt1, treatment of the cell with leukemia inhibitory factor (LIF), and cAMP analog (CREB activator) enhanced the expression of endogenous Opalin in Oli-neu cells and activated the oligodendrocyte enhancer. These results suggest that LIF, cAMP signaling cascades and Myt1 play significant roles in the differentiation of oligodendrocytes through their action on the Opalin oligodendrocyte enhancer.

Impaired cerebellar development and function in mice lacking CAPS2, a protein involved in neurotrophin release

Ca2+-dependent activator protein for secretion 2 (CAPS2/CADPS2) is a secretory granule-associated protein that is abundant at the parallel fiber terminals of granule cells in the mouse cerebellum and is involved in the release of neurotrophin-3 (NT-3) and brain-derived neurotrophic factor (BDNF), both of which are required for cerebellar development. The human homolog gene on chromosome 7 is located within susceptibility locus 1 of autism, a disease characterized by several cerebellar morphological abnormalities. Here we report that CAPS2 knock-out mice are deficient in the release of NT-3 and BDNF, and they consequently exhibit suppressed phosphorylation of Trk receptors in the cerebellum; these mice exhibit pronounced impairments in cerebellar development and functions, including neuronal survival, differentiation and migration of postmitotic granule cells, dendritogenesis of Purkinje cells, lobulation between lobules VI and VII, structure and vesicular distribution of parallel fiber-Purkinje cell synapses, paired-pulse facilitation at parallel fiber-Purkinje cell synapses, rotarod motor coordination, and eye movement plasticity in optokinetic training. Increased granule cell death of the external granular layer was noted in lobules VI-VII and IX, in which high BDNF and NT-3 levels are specifically localized during cerebellar development. Therefore, the deficiency of CAPS2 indicates that CAPS2-mediated neurotrophin release is indispensable for normal cerebellar development and functions, including neuronal differentiation and survival, morphogenesis, synaptic function, and motor learning/control. The possible involvement of the CAPS2 gene in the cerebellar deficits of autistic patients is discussed.

Autistic-like phenotypes in Cadps2-knockout mice and aberrant CADPS2 splicing in autistic patients

Autism, characterized by profound impairment in social interactions and communicative skills, is the most common neurodevelopmental disorder, and its underlying molecular mechanisms remain unknown. Ca(2+)-dependent activator protein for secretion 2 (CADPS2; also known as CAPS2) mediates the exocytosis of dense-core vesicles, and the human CADPS2 is located within the autism susceptibility locus 1 on chromosome 7q. Here we show that Cadps2-knockout mice not only have impaired brain-derived neurotrophic factor release but also show autistic-like cellular and behavioral phenotypes. Moreover, we found an aberrant alternatively spliced CADPS2 mRNA that lacks exon 3 in some autistic patients. Exon 3 was shown to encode the dynactin 1-binding domain and affect axonal CADPS2 protein distribution. Our results suggest that a disturbance in CADPS2-mediated neurotrophin release contributes to autism susceptibility.

HOMER2 binds MYO18B and enhances its activity to suppress anchorage independent growth

MYO18B is a class XVIII myosin, cloned as a tumor suppressor gene candidate. To investigate the mechanisms of MYO18B-dependent tumor suppression, MYO18B-interacting proteins were searched for by a yeast two-hybrid screen. HOMER2, a Homer/Ves1 family protein, was identified as a binding partner of MYO18B. These proteins co-localized in the regions of membrane protrusion and stress fiber, which are known as ones with filamentous actin-rich structures. Expression of HOMER2 enhanced the ability of MYO18B to suppress anchorage-independent growth. These results indicate that HOMER2 and MYO18B cooperate together in tumor suppression.

The fundamental properties of Homer 1 in association with cardiac ryanodine receptor in mouse heart

BACKGROUND

Homer, known as a scaffolding protein that regulates postsynapse signaling in neurons, has been poorly explored in cardiac research. We show the fundamental properties of Homer 1 in mouse heart in association with cardiac ryanodine receptor (RyR), a binding protein of Homer 1.

METHODS AND RESULTS

Immunohistochemistry of adult mouse heart with Homer 1 antibody showed striated staining on Z-bands both in atria and ventricles. The interactions between Homer 1 and RyR were confirmed by co-immunoprecipitation assays. Immunostaining of adult isolated cardiomyocytes showed partial co-localization of both proteins. In neonatal primary cultures, targeting of Homer 1 preceded that of RyR in their Z-band arrangement.

CONCLUSIONS

Homer 1 binds to RyR in adult mouse heart and precedes RyR in Z-band arrangement in the early postnatal period.

Tissue distribution of Ca2+-dependent activator protein for secretion family members CAPS1 and CAPS2 in mice

The family of Ca2+-dependent activator proteins for secretion (CAPS) is involved in dense-core vesicle exocytosis. CAPS1/CADPS1 and CAPS2/CADPS2 have been identified in mammals. CAPS1 regulates catecholamine release from neuroendocrine cells, whereas CAPS2 is involved in the release of brain-derived neurotrophic factor and neurotrophin-3 from cerebellar granule cells. CAPS1 and CAPS2 are predominantly expressed in brain. Here we show the immunohistochemical localization of the CAPS family proteins in various mouse tissues. In the pituitary gland, CAPS1 and CAPS2 were localized to the pars nervosa and the pars intermedia, respectively. In non-neural tissues, CAPS1 was observed in the islets of Langerhans, minor cell types of the spleen and stomach, and medullary cells of the adrenal gland, whereas CAPS2 was present in bronchial epithelial cells, thyroid parafollicular cells, chief cells of the stomach, ductal epithelium of the salivary gland, kidney proximal tubules, and minor cell types of the thymus, spleen, and colon. These results suggest that secretion from distinct cell types in various tissues involves either or both members of the CAPS family.

Spatial expression patterns and biochemical properties distinguish a second myo-inositol monophosphatase IMPA2 from IMPA1

Lithium is used in the clinical treatment of bipolar disorder, a disease where patients suffer mood swings between mania and depression. Although the mode of action of lithium remains elusive, a putative primary target is thought to be inositol monophosphatase (IMPase) activity. Two IMPase genes have been identified in mammals, the well characterized myo-inositol monophosphatase 1 (IMPA1) and myo-inositol monophosphatase 2 (IMPA2). Several lines of genetic evidence have implicated IMPA2 in the pathogenesis of not only bipolar disorder but also schizophrenia and febrile seizures. However, little is known about the protein, although it is predicted to have lithium-inhibitable IMPase activity based on its homology to IMPA1. Here we present the first biochemical study comparing the enzyme activity of IMPA2 to that of IMPA1. We demonstrate that in vivo, IMPA2 forms homodimers but no heterodimers with IMPA1. Recombinant IMPA2 exhibits IMPase activity, although maximal activity requires higher concentrations of magnesium and a higher pH. IMPA2 shows significantly lower activity toward myo-inositol monophosphate than IMPA1. We therefore screened for additional substrates that could be more efficiently dephosphorylated by IMPA2, but failed to find any. Importantly, when using myo-inositol monophosphate as a substrate, the IMPase activity of IMPA2 was inhibited at high lithium and restricted magnesium concentrations. This kinetics distinguishes it from IMPA1. We also observed a characteristic pattern of differential expression between IMPA1 and IMPA2 in a selection of tissues including the brain, small intestine, and kidney. These data suggest that IMPA2 has a separate function in vivo from that of IMPA1.

Identification and mRNA expression of Ogdh, QP-C, and two predicted genes in the postnatal mouse brain

By fluorescent differential display, we identified six transcripts (CAPS2/Cadps2, Cdh22, b1402, c1502, d1401, and d1501) that showed the differential expression patterns during the postnatal development of the mouse cerebellum. We further analyzed the latter four transcripts whose cellular localizations in developing mouse brains have not been studied. In the postnatal cerebellum, clones c1502 and d1501 were transiently up-regulated; clone b1402 was up-regulated; and clone d1401 remained relatively constant. Sequence analysis revealed that d1401 and c1502 were derivatives of Ogdh (oxoglutarate dehydrogenase) and QP-C (ubiquinol-cytochrome c reductase complex ubiquinone-binding protein), respectively. Moreover, b1402 and d1501 were identified as transcripts of a predicted gene (4933409K07Rik) and a novel EST, respectively. b1402 and d1501 were abundantly present in the cerebellum, whereas c1502/QP-C and d1401/Ogdh were widely distributed in various mouse tissues. In the postnatal mouse brain, moderately high mRNA levels of b1402 were restricted to the olfactory bulb, striatum, cerebral cortex (layers II-III and VI), hippocampus (dentate granule cells), and cerebellum (granule cells). c1502/QP-C mRNA was localized at high levels in the olfactory bulb, cerebral cortex, hippocampus, thalamus (anterodorsal nucleus, parafacicularis nucleus), tegmentum (red nucleus), cerebellum (Purkinje and granule cells), and pons (pontine nucleus, reticulotegmental nucleus, trapezoid body, vestibular nucleus). High mRNA levels of d1401/Ogdh were observed in the olfactory bulb, hippocampus, cerebellum, and pons, whereas those of d1501 were detected in the granule cells of the olfactory bulb, dentate gyrus, and cerebellum.