Sur2 and Kcnj8 genes are tightly linked on the distal region of mouse chromosome 6.
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ATP-Binding Cassette Transporters↗
Biomedical subjects
D J Gilbert
Publications and source records attributed to D J Gilbert.
Crx, a novel Otx-like paired-homeodomain protein, binds to and transactivates photoreceptor cell-specific genes.
The otd/Otx gene family encodes paired-like homeodomain proteins that are involved in the regulation of anterior head structure and sensory organ development. Using the yeast one-hybrid screen with a bait containing the Ret 4 site from the bovine rhodopsin promoter, we have cloned a new member of the family, Crx (Cone rod homeobox). Crx encodes a 299 amino acid residue protein with a paired-like homeodomain near its N terminus. In the adult, it is expressed predominantly in photoreceptors and pinealocytes. In the developing mouse retina, it is expressed by embryonic day 12.5 (E12.5). Recombinant Crx binds in vitro not only to the Ret 4 site but also to the Ret 1 and BAT-1 sites. In transient transfection studies, Crx transactivates rhodopsin promoter-reporter constructs. Its activity is synergistic with that of Nrl. Crx also binds to and transactivates the genes for several other photoreceptor cell-specific proteins (interphotoreceptor retinoid-binding protein, beta-phosphodiesterase, and arrestin). Human Crx maps to chromosome 19q13.3, the site of a cone rod dystrophy (CORDII). These studies implicate Crx as a potentially important regulator of photoreceptor cell development and gene expression and also identify it as a candidate gene for CORDII and other retinal diseases.
Amino Acid Sequence↗
TECK: a novel CC chemokine specifically expressed by thymic dendritic cells and potentially involved in T cell development.
A novel CC chemokine was identified in the thymus of mouse and human and was designated TECK (thymus-expressed chemokine). TECK has weak homology to other CC chemokines and maps to mouse chromosome 8. Besides the thymus, mRNA encoding TECK was detected at substantial levels in the small intestine and at low levels in the liver. The source of TECK in the thymus was determined to be thymic dendritic cells; in contrast, bone marrow-derived dendritic cells do not express TECK. The murine TECK recombinant protein showed chemotactic activity for activated macrophages, dendritic cells, and thymocytes. We conclude that TECK represents a novel thymic dendritic cell-specific CC chemokine that is possibly involved in T cell development.
Amino Acid Sequence↗
Chromosomal localization of the myelin-associated oligodendrocytic basic protein and expression in the genetically linked neurological mouse mutants ducky and tippy.
The alternatively spliced cDNAs encoding the myelin-associated/oligodendrocytic basic proteins (MOBPs) have recently been identified in rat. The Mobp gene maps to the distal part of mouse chromosome 9 at a region syntenic with the human chromosome 3p22-p21.3. Two nonallelic mouse mutants, tippy and ducky, with severe neurological phenotypes map to the vicinity of the Mobp locus. We therefore tested whether MOBP malfunction could explain the tippy and ducky defects. In tippy mutant animals, MOBP expression and that of other myelin markers were indistinguishable from wild type. The ultrastructure of tippy myelin was shown to be normal. Ducky animals showed a slight reduction of the brain size, most evident in the spinal cord, but normal progress of myelination. Both MOBP and myelin basic protein expression were lowered only regionally in the CNS, but were mostly normal in the anterior parts of the brain. Ultrastructurally, ducky myelin appeared normal. MOBP transcript sizes and the molecular weights of the encoded proteins were shown to be normal in both mutants. Finally, the nucleotide sequence of the abundant MOBP-81 cDNA was determined and compared with tippy and ducky MOBP-81. Wild-type mouse MOBP-81 protein was 99% identical to the rat homologue, and tippy and ducky MOBP-81 were identical to the wild-type sequence. Our results suggest that alterations in the Mobp gene are not the cause for the severe neurological phenotypes of ducky and tippy mice.
Alternative Splicing↗
The genes encoding the peripheral cannabinoid receptor and alpha-L-fucosidase are located near a newly identified common virus integration site, Evi11.
A new common region of virus integration, Evi11, has been identified in two retrovirally induced murine myeloid leukemia cell lines, NFS107 and NFS78. By interspecific backcross analysis, it was shown that Evi11 is located at the distal end of mouse chromosome 4, in a region that shows homology with human 1p36. The genes encoding the peripheral cannabinoid receptor (Cnr2) and alpha-L-fucosidase (Fuca1) were identified near the integration site by using a novel exon trapping system. Cnr2 is suggested to be the target gene for viral interference in Evi11, since proviruses are integrated in the first intron of Cnr2 and retroviral integrations alter mRNA expression of Cnr2 in NFS107 and NFS78. In addition, proviral integrations were demonstrated within the 3' untranslated region of Cnr2 in five independent newly derived CasBrM-MuLV (mouse murine leukemia virus) tumors, CSL13, CSL14, CSL16, CSL27, and CSL97. The Cnr2 gene encodes a seven-transmembrane G-protein-coupled receptor which is normally expressed in hematopoietic tissues. Our data suggest that the peripheral cannabinoid receptor gene might be involved in leukemogenesis as a result of aberrant expression of Cnr2 due to retroviral integration in Evi11.
3T3 Cells↗
Two isoforms of the mouse ether-a-go-go-related gene coassemble to form channels with properties similar to the rapidly activating component of the cardiac delayed rectifier K+ current.
HERG, the human ether-a-go-go-related gene, encodes a K(+)-selective channel with properties similar to the rapidly activating component of the delayed rectifier K+ current (IKr). Mutations of HERG cause the autosomal-dominant long-QT syndrome (LQTS), presumably by disrupting the normal function of IKr. The current produced by HERG is not identical to IKr, however, and the mechanism by which HERG mutations cause LQTS remains uncertain. To better define the role of Erg in the heart, we cloned Merg1 from mouse genomic and cardiac cDNA libraries. Merg1 has 16 exons and maps to mouse chromosome 5 in an area syntenic to human chromosome 7q, the map locus of HERG. We isolated three cardiac isoforms of Merg1: Merg1a is homologous to HERG and is expressed in heart, brain, and testes, Merg1a' lacks the first 59 amino acids of Merg1a and is not expressed abundantly, and Merg1b has a markedly shorter divergent N-terminal cytoplasmic domain and is expressed specifically in the heart. The Merg1 isoforms, like HERG, produce inwardly rectifying E-4031-sensitive currents when heterologously expressed in Xenopus oocytes. Merg1a and HERG produce currents with slow deactivation kinetics, whereas Merg1a' and Merg1b currents deactivate more rapidly. Merg1b coassembles with Merg1a to form channels with deactivation kinetics that are more rapid than those of Merg1a or HERG and nearly identical to IKr. In addition, a homologue of Merg1b is present in human cardiac and smooth muscle. Thus, we have identified a novel N-terminal Erg isoform that is expressed specifically in the heart, has rapid deactivation kinetics, and coassembles with the longer isoform in Xenopus oocytes. This N-terminal Erg isoform may determine the properties of IKr and contribute to the pathogenesis of LQTS.
Amino Acid Sequence↗
Cloning, chromosomal localization, and functional analysis of the murine estrogen receptor beta.
Estrogen receptor beta (ER beta) is a novel steroid receptor that is expressed in rat prostate and ovary. We have cloned the mouse homolog of ER beta and mapped the gene, designated Estrb, to the central region of chromosome 12. The cDNA encodes a protein of 485 amino acids that shares, respectively, 97% and 60% identity with the DNA- and ligand-binding domains of mouse (m) ER alpha. Mouse ER beta bind to an inverted repeat spaced by three nucleotides in a gel mobility shift assay and transactivates promoters containing synthetic or natural estrogen response elements in an estradiol (E2)-dependent manner. Scatchard analysis indicates that mER beta has slightly lower affinity for E2 [dissociation constant (Kd) = 0.5 nM] when compared with mER alpha (Kd = 0.2 nM). Antiestrogens, including 4-hydroxytamoxifen (OHT), ICI 182,780, and a novel compound, EM-800, inhibit E2-dependent transactivation efficiently. However, while OHT displays partial agonistic activity with ER alpha on a basal promoter linked to estrogen response elements in Cos-1 cells, this effect is not observed with mER beta. Cotransfection of mER beta and H-RasV12 causes enhanced activation in the presence of E2. Mutagenesis of a serine residue (position 60), located within a mitogen-activated protein kinase consensus phosphorylation site abolishes the stimulatory effect of Ras, suggesting that the activity of mER beta is also regulated by the mitogen-activated protein kinase pathway. Surprisingly, the coactivator SRC-1 up-regulates mER beta transactivation both in the absence and presence of E2, and in vitro interaction between SRC-1 and the ER beta ligand-binding domain is enhanced by E2. Moreover, the ligand-independent stimulatory effect of SRC-1 on ER beta transcriptional activity is abolished by ICI 182,780, but not by OHT. Our results demonstrate that while ER beta shares many of the functional characteristics of ER alpha, the molecular mechanisms regulating the transcriptional activity of mER beta may be distinct from those of ER alpha.
Amino Acid Sequence↗
Mapping of the gene for vascular endothelial growth factor-D in mouse and man to the X chromosome.
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Animals↗
Identification of a novel selD homolog from eukaryotes, bacteria, and archaea: is there an autoregulatory mechanism in selenocysteine metabolism?
Escherichia coli selenophosphate synthetase (SPS, the selD gene product) catalyzes the production of monoselenophosphate, the selenium donor compound required for synthesis of selenocysteine (Sec) and seleno-tRNAs. We report the molecular cloning of human and mouse homologs of the selD gene, designated Sps2, which contains an in-frame TGA codon at a site corresponding to the enzyme's putative active site. These sequences allow the identification of selD gene homologs in the genomes of the bacterium Haemophilus influenzae and the archaeon Methanococcus jannaschii, which had been previously misinterpreted due to their in-frame TGA codon. Sps2 mRNA levels are elevated in organs previously implicated in the synthesis of selenoproteins and in active sites of blood cell development. In addition, we show that Sps2 mRNA is up-regulated upon activation of T lymphocytes and have mapped the Sps2 gene to mouse chromosome 7. Using the mouse gene isolated from the hematopoietic cell line FDCPmixA4, we devised a construct for protein expression that results in the insertion of a FLAG tag sequence at the N terminus of the SPS2 protein. This strategy allowed us to document the readthrough of the in-frame TGA codon and the incorporation of 75Se into SPS2. These results suggest the existence of an autoregulatory mechanism involving the incorporation of Sec into SPS2 that might be relevant to blood cell biology. This mechanism is likely to have been present in ancient life forms and conserved in a variety of living organisms from all domains of life.
Amino Acid Sequence↗
The carboxyl-terminal domain of phosphophoryn contains unique extended triplet amino acid repeat sequences forming ordered carboxyl-phosphate interaction ridges that may be essential in the biomineralization process.
Phosphophoryns (PPs), a family of Asp and Ser(P)-rich dentin proteins, are considered to be archetypal regulators of several aspects of extracellular matrix (ECM) biomineralization. We have cloned a rat incisor PP gene, Dmp2, from our odontoblast cDNA library and localized it to mouse chromosome 5q21 within 2 centimorgans of Dmp1, another tooth-specific ECM protein. The carboxyl-terminal region of Dmp2 protein (60 residue % Ser, 31 residue % Asp) is divided into two domains, one with unique repetitive blocks of [DSS]n,3</=14, the other with [SD]m = 2,3. Conformational analysis shows the phosphorylated form of the [DS*S*]n repeats to have a unique structure with well defined ridges of phosphates and carboxyls available for counter ion binding. The [S*D]m domains have different phosphate and carboxylate interaction edges and thus different calcium ion and apatite surface binding properties. These two domains and the colocalization of Dmp1 and Dmp2 genes at a position equivalent to the dentinogenesis imperfecta type II location on human 4q21 all suggest that the PPs are indeed involved in some aspect of ECM mineralization.
Amino Acid Sequence↗
Molecular cloning of a human RP105 homologue and chromosomal localization of the mouse and human RP105 genes (Ly64 and LY64).
RP105 is a mouse B cell surface molecule that transmits a growth-promoting signal and is implicated in the life/death decision of B cells. RP105 has tandem repeats of a leucine-rich motif in the extracellular domain that is expected to be involved in protein-protein interactions. In the present study, a cDNA clone encoding the human homologue of RP105 was isolated. The amino acid sequence of human RP105 is highly homologous to that of mouse RP105 with 74% identity, and the leucine-rich repeats are well conserved. The expression of the human RP105 transcript was detected in some B cell lines, a histiocytic leukemia cell line, and peripheral blood leukocytes. We also determined the chromosomal locations of the mouse RP105 gene (Ly64 locus) and the human RP105 gene (LY64 locus). Interspecific mouse backcross analysis was used to map the Ly64 locus at the distal region of chromosome 13. The human LY64 locus was localized to 5q12 by fluorescence in situ hybridization, confirming the syntenic relationship between these regions of the mouse and human chromosomes.
Amino Acid Sequence↗
Isolation of a NCK-associated kinase, PRK2, an SH3-binding protein and potential effector of Rho protein signaling.
The NCK adapter protein is comprised of three consecutive Src homology 3 (SH3) protein-protein interaction domains and a C-terminal SH2 domain. Although the association of NCK with activated receptor protein-tyrosine kinases, via its SH2 domain, implicates NCK as a mediator of growth factor-induced signal transduction, little is known about the pathway(s) downstream of NCK recruitment. To identify potential downstream effectors of NCK we screened a bacterial expression library to isolate proteins that bind its SH3 domains. Two molecules were isolated, the Wiskott-Aldrich syndrome protein (WASP, a putative CDC42 effector) and a serine/threonine protein kinase (PRK2, closely related to the putative Rho effector PKN). Using interspecific backcross analysis the Prk2 gene was mapped to mouse chromosome 3. Unlike WASP, which bound the SH3 domains of several signaling proteins, PRK2 specifically bound to the middle SH3 domain of NCK and (weakly) that of phospholipase Cgamma. PRK2 also specifically bound to Rho in a GTP-dependent manner and cooperated with Rho family proteins to induce transcriptional activation via the serum response factor. These data suggest that PRK2 may coordinately mediate signal transduction from activated receptor protein-tyrosine kinases and Rho and that NCK may function as an adapter to connect receptor-mediated events to Rho protein signaling.
3T3 Cells↗
Sequence and chromosomal localization of mouse annexin XI.
Mouse annexin XI (anx11)2 was cloned from a macrophage cDNA library and characterized by genetic linkage mapping, DNA sequencing, and structural comparison with other annexins. The Anx11 gene localized to mouse chromosome 14 in close linkage with the Rarb, Plau, and Wnt5a genes near the centromere and 1.8 cM distal from the Anx7 gene. The open reading frame was flanked by long, untranslated regions and encoded a 503-amino-acid protein with 93.1% identity to its human orthologue. Its 189-aa amino terminus corresponded to the widely expressed variant 1 of two possible, alternatively spliced forms. A previously described peptide from Aplysia brasiliana was identified as a closely related invertebrate homologue. Since annexin XI is known to be localized in the nucleus at certain stages of development, the identification of a region in tetrad repeats 3 and 4 resembling the "chromo box" domain may be relevant to a nuclear regulatory function of annexin XI. Knowledge of the mouse cDNA sequence and genetic map location will assist in the analysis of genomic organization and expression and provide a useful animal model to investigate gene function and hereditary phenotype for annexin XI.
Amino Acid Sequence↗
Cloning, RNA expression, and chromosomal location of a mouse histamine H2 receptor gene.
A mouse histamine H2 receptor (H2R) gene was isolated from a mouse ES cell genomic DNA library. The gene encoded a 358-amino-acid protein and displayed a 95% homology with the rat histamine H2 receptor at the amino acid level. It had features characteristic of other G-protein-coupled receptors. Reverse transcriptase-polymerase chain reaction analysis of total RNA prepared from mouse tissues showed that the gene was highly expressed in stomach and moderately in brain and heart. A weak expression was also detected in liver. An interspecific backcross analysis revealed that the mouse H2R gene, designated Hrh2, was located in the central region of chromosome 13.
Amino Acid Sequence↗
Assignment of the murine inward rectifier potassium channel Irk2 (Kir2.2) gene to the central region of mouse chromosome 11.
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Animals↗
Elk-L3, a novel transmembrane ligand for the Eph family of receptor tyrosine kinases, expressed in embryonic floor plate, roof plate and hindbrain segments.
The Eph family of receptor tyrosine kinases has 13 distinct members and seven ligands for these receptors have been described to date. These receptors and their ligands have been implicated in regulating neuronal axon guidance and in patterning of the developing nervous system and may also serve a patterning and compartmentalization role outside of the nervous system as well. The ligands are all membrane-attached, and this attachment appears to be crucial for their normal function; five of the known ligands are linked to the membrane via a glycosyl phosphotidylinositol (GPI) linkage, while two of the ligands are transmembrane proteins. Despite the large number of Eph family receptors and ligands, they can be divided into just two major subclasses based on their binding specificities. All the GPI-anchored ligands bind and activate one subclass of the Eph receptors (that represented by Eck) while the two transmembrane ligands bind and activate the other major subclass of receptors (represented by Elk). Here we report the identification and characterization of the third, and most divergent, member of the transmembrane group of Eph ligands, which we term Elk-L3 (Elk-related receptor ligand number 3). Elk-L3 is notable for its remarkably restricted and prominent expression in the floor plate and roof plate of the developing neural tube and its rhombomere-specific expression in the developing hindbrain. The Elk-L3 gene has been localized to mouse chromosome 11 and human chromosome 17.
Amino Acid Sequence↗
Gcm1, a mammalian homolog of Drosophila glial cells missing.
Differentiation of glia (astrocytes and oligodendrocytes) in Drosophila requires the gene glial cells missing (gcm), which controls lineage determination. In the absence of gcm, neuroglia progenitors exclusively differentiate into neurons, instead of into both neurons and glia. In contrast, ectopic overexpression of gcm causes uniform differentiation of the neuroglia progenitors into glia. Glial and neuronal cells in vertebrates similarly derive from neuroblast progenitors. To investigate vertebrate glial formation, we have identified, cloned, and chromosomally mapped a mammalian gcm homolog. Mouse Gcm1 demonstrates extensive similarity to Drosophila gcm but is expressed at very low levels during neuro- and gliogenesis.
Amino Acid Sequence↗
Mapping of unconventional myosins in mouse and human.
Myosins are molecular motors that move along filamentous actin. Seven classes of myosin are expressed in vertebrates: conventional myosin, or myosin-II, as well as the 6 unconventional myosin classes-I, -V, -VI, -VII, -IX, and -X. We have mapped in mouse 22 probes encompassing all known unconventional myosins and, as a result, have identified 16 potential unconventional myosin genes. These genes include 7 myosins-I, 2 myosins-V, 1 myosin-VI, 3 myosins-VII, 2 myosins-IX, and 1 myosin-X. The map location of 5 of these genes was identified in human chromosomes by fluorescence in situ hybridization.
Animals↗