An integrated CMOS microluminometer for low-level luminescence sensing in the bioluminescent bioreporter integrated circuit

We report an integrated CMOS microluminometer for the detection of low-level bioluminescence in whole cell biosensing applications. This microluminometer is the microelectronic portion of the bioluminescent bioreporter integrated circuit (BBIC). This device uses the n-well/p-substrate junction of a standard bulk CMOS IC process to form the integrated photodetector. This photodetector uses a distributed electrode configuration that minimizes detector noise. Signal processing is accomplished with a current-to-frequency converter circuit that forms the causal portion of the matched filter for dc luminescence in wide-band white noise. Measurements show that luminescence can be detected from as few as 4 x 10(5) cells/ml.

Fine localization of the CMT4A locus using a PAC contig and haplotype analysis

Charcot-Marie-Tooth disease type 4A (CMT4A) is a severe, autosomal recessive peripheral neuropathy linked to chromosome 8q13-q21. We have previously constructed a YAC contig across the CMT4A region and narrowed the disease-flanking interval to approximately three megabases. Subsequently, we constructed a PAC/BAC contig made of 44 clones and mapped 44 new and 30 previous STSs, ESTs, and polymorphic makers to the region. Using 13 polymorphic markers, we have now identified an ancestral haplotype segregating in three families, indicating a common founder mutation. Two ancestral recombination events in this haplotype significantly reduce the minimal candidate region to a minimal trailing path of five PAC/BAC clones, which will now allow direct investigation of candidate genes for CMT4A.

Molecular properties and chromosomal location of cadherin-8

Cloning of rat cadherin-8 cDNA demonstrated two types of cDNAs. The overall structure of the protein defined by one type of the cDNA is essentially the same as that of classic cadherins, whereas the protein defined by the other type of cDNA ends near the N-terminus of the fifth repeat of the extracellular domain (EC5) and contains a short unique sequence at the C-terminus. The same truncated type of cDNA was also obtained from a human cDNA library. In Northern blot analysis of rat brain mRNA, a probe for EC5 detected multiple bands of about 3.5-4.3 knt, whereas a probe for the alternative form hybridized with a band of about 3.5 knt. Western blot experiments showed that an antibody against the extracellular domain of rat cadherin-8 stained a band of about 95 kDa and a faint band of about 130 kDa in rat brain extract. These results suggest that cadherin-8 is expressed in two forms, a complete form and a truncated form without a transmembrane domain or cytoplasmic domain, in brain. The complete form of cadherin-8 expressed in L cells was about 130 kDa in molecular mass and was located at the cell periphery, mainly at the cell-cell contact sites. However, we failed to express the truncated form in L cells. The transfectants of the complete form showed weak cell adhesion activity. The complete form of cadherin-8 was sensitive to trypsin digestion, and Ca2+ did not protect cadherin-8 from digestion, in contrast to the classic cadherins. The complete form of cadherin-8 coprecipitated with beta-catenin, but did not immunoprecipitate well with alpha-catenin or gamma-catenin. Cadherin-8, as well as cadherin-11, was mapped to a specific region of chromosome 8 that also includes cadherins-1, -3, and -5.

Mapping of eight testis-specific genes to mouse chromosomes

We previously identified eight testis-specific genes using antibodies raised against testicular germ cells. They are expressed during spermatogenesis and are presumed to be involved in testicular germ cell differentiation and sperm formation. We have mapped the genomic loci for these testis-specific genes using restriction fragment length variants in interspecific backcross mice. The calmegin gene (Clgn) was mapped to Chr 8. The synaptonemal complex protein gene 1 (Sycp1) probe hybridized with two sequences on different chromosomes; Sycp1-rs2 was mapped to Chr 3, whereas Sycp1-rs3 was mapped to Chr 7. The relaxin-like factor gene (Rlnl) was mapped to Chr 8, and collapsin response mediator protein 1 (Crmp1) was mapped to Chr 5. Three novel genes encoding testis-specific proteins A2 (Tsga2), A8 (Tsga8), and A12 (Tsga12) were mapped to chromosomes 3, X, and 10, respectively.

Genomic organization, expression, and chromosomal mapping of the mouse adrenomedullin gene

We have isolated and characterized the mouse adrenomedullin (AM) gene (Adm) and determined its chromosomal location. The gene spans approximately 2.1 kb and is organized into four exons separated by three introns. The transcription start site was determined to be the adenine nucleotide at -618. The mouse AM 5'-flanking region contains a TATA box-like sequence and several cis-acting regulatory elements. Analysis of the nucleotide and deduced amino acid sequences revealed that mouse preproAM is a 184-amino-acid polypeptide, from which AM and proAM N-terminal 20 peptide are cleaved. Using restriction fragment length variants on a DNA panel of interspecific backcross mice, we mapped Adm to a distal region of mouse chromosome 7.

Mouse Sin3A interacts with and can functionally substitute for the amino-terminal repression of the Myc antagonist Mxi1

Mxi1 is a basic region helix-loop-helix leucine zipper (bHLH/LZ) protein that, in association with Max, antagonizes Myc oncogenic activities. A possible mechanistic basis for Mxi1-mediated repression was provided by the recent demonstration that the repressive potential of Mxi1 correlates with its ability to physically associate with mSin3B, one of two mammalian homologues of the yeast transcriptional repressor SIN3. Here, we sought to characterize more fully the physical properties of the second homologue, mSin3A and to determine whether the recruitment of mSin3A by Mxi1 is indeed required for anti-Myc activity. Transient transfection of mammalian cells showed that the mSin3A protein can associate with the strong repressive isoform of Mxi1 (Mxi1-SR) and that, like other Myc superfamily members, both mSin3A and Mxi1-SR localize to the nucleus. From a developmental standpoint, a comparative analysis of Myc, Mxi1-SR and Sin3A expression during postnatal mouse development and in differentiating mouse erythroleukemia (MEL) cells revealed that dramatic and reciprocal changes in Myc and Mxi1-SR mRNA levels are accompanied by minimal stage-specific changes in mSin3A gene expression. This constant expression profile, coupled with the observation that over-expression of mSin3A does not augment the anti-Myc activity of Mxi1-SR in the rat embryo fibroblast (REF) transformation assay, suggests that mSin3A is not a limiting factor in the regulation of Myc superfamily function. Finally, a mSin3A-Mxi1 fusion protein, in which the amino terminal mSin3-interacting domain of Mxi1-SR was replaced with the full-length mSin3A, exhibited a level of repression activity equivalent to, or greater than, the level of repression obtained with Mxi1-SR. Taken together, these observations directly demonstrate that the amino-terminal repression domain of Mxi1-SR functions solely to recruit mSin3A and possibly other proteins like mSin3A and this association is necessary for the anti-Myc activity of Mxi1-SR.

Mapping of the genes encoding mouse prostaglandin D, E, and F and prostacyclin receptors

Prostaglandins and prostacyclin are metabolites of arachidonic acid and exert a variety of actions to maintain local homeostasis in the body. Their actions are mediated by cell surface receptors specific to the respective ligands. Using a panel of interspecific back-cross mice, we have mapped the prostaglandin D receptor gene (Ptgdr), prostaglandin E receptor subtype EP(1) gene (Ptgerepl), prostaglandin F receptor gene (Ptgfr), and prostacyclin receptor gene (Ptgir). Ptgdr mapped to proximal Chr 14, Ptgfr mapped to distal Chr 3, Ptgerepl mapped to middle Chr 8, and Ptgir mapped to proximal Chr 7.

Protocadherin Pcdh2 shows properties similar to, but distinct from, those of classical cadherins

Cell adhesion and several other properties of a recently identified cadherin-related protein, protocadherin Pcdh2, were characterized. A chimeric Pcdh2 in which the original cytoplasmic domain was replaced with the cytoplasmic domain of E-cadherin was expressed in mouse L cells. The expressed protein had a molecular mass of about 150 kDa and was localized predominantly at the cell periphery, as was the wild-type Pcdh2. In a conventional cell aggregation assay, the transfectants showed cell aggregation activity comparable to that of classical cadherins. This activity was Ca(2+)-dependent and was inhibited by the addition of anti-Pcdh2 antibody, indicating that the chimeric Pcdh2, and probably the wild-type Pcdh2, has Ca(2+)-dependent cell aggregation activity. Mixed cell aggregation assay using L cells and different types of transfectants showed that the activity of Pcdh2 was homophilic and molecular type specific and that Pcdh2 was transfectants did not aggregate with other types of transfectants or with L cells. In immunoprecipitation, the chimeric Pcdh2 co-precipitated with a 105 kDa and a 95 kDa protein, whereas wild-type Pcdh2 co-precipitated with no major protein. Pcdh2 was easily solubilized with non-ionic detergent, in contrast to the case of classical cadherins. On immunofluorescence microscopy, the somas of Purkinje cells were diffusely stained with anti-human Pcdh2 antibody. Mouse Pcdh1 and Pcdh2 were mapped to a small segment of chromosome 18, suggesting that various protocadherins form a gene cluster at this region. The present results suggest that Pcdh2, and possibly other protocadherins as well as protocadherin-related proteins such as Drosophila fat, mediate Ca(2+)-dependent and specific homophilic cell-cell interaction in vivo and play an important role in cell adhesion, cell recognition, and/or some other basic cell processes.

Cloning, expression, and chromosomal localization of a novel cadherin-related protein, protocadherin-3

To study the diversity of the protocadherin family, the cDNA clones for a novel protocadherin were isolated by screening rat brain cDNA libraries with a cDNA fragment obtained by PCR, and some of the properties were then characterized. The overall structure of the protein defined by the clone is similar to that of previously identified protocadherins; however, the cytoplasmic domain is distinct from those of previously cloned protocadherins or any other protein sequences in the data bank. We named this protocad herin-3 (Pcdh3) since this is the third protocadherin of which the entire coding sequence has been determined. Most of the deduced amino acid sequences of other cDNA clones obtained by the screening show high homology with but are distinct from that of Pcdh3, indicating that most of these sequences correspond to homologous but different protocadherins. These results demonstrate that Pcdh3 and the protocadherins defined by these clones constitute a protocadherin subfamily. Chromosome mapping indicates that mouse Pcdh3 is located in a specific region of mouse chromosome 18, close to the location of previously cloned protocadherins, suggesting that various protocadherins form a cluster in this region. In situ hybridization results showed that Pcdh3 and its related proteins were expressed at various areas in brain. The expressed Pcdh3 protein from the cDNA in mouse L cells was about 100 kDa in molecular weight and was localized at cell-cell contact sites. In contrast to the classical cadherins, however, the expressed Pcdh3 was sensitive to trypsin even in the presence of Ca2+, and the transfectants did not show strong Ca(2+)-dependent cell aggregation activity. These results indicate the structural and possibly functional diversity of the protocadherin family and suggest a distinctive biological role for Pcdh3.

Mapping of the 75-kDa inositol polyphosphate-5-phosphatase (Inpp5b) to distal mouse chromosome 4 and its exclusion as a candidate gene for dysgenetic lens

We have determined the chromosomal localization of the murine gene encoding a 75-kDa inositol polyphosphate-5-phosphatase (Inpp5b). Using two independent approaches, fluorescence in situ hybridization and interspecific backcross analysis, we show that Inpp5b maps to distal mouse Chromosome 4. This map position is within the conserved linkage group corresponding to the short arm of human Chromosome 1, where the human homologue, INPP5B, has been shown to map previously. The position of Inpp5b on mouse Chromosome 4 is in the vicinity of the mouse developmental mutation dysgenetic lens (dyl). However, using a genetic approach, we show that Inpp5b maps distal to dyl on mouse Chromosome 4.

Chromosomal localization of the gene encoding the human DNA helicase RECQL and its mouse homologue

We have determined the chromosomal location of the human and mouse genes encoding the RECQL protein, a putative DNA helicase homologous to the bacterial DNA helicase, RecQ. RECQL was localized to human chromosome 12 by analysis of human-rodent somatic cell hybrid DNA; fine mapping of RECQL by fluorescence in situ hybridization revealed its chromosomal location to be 12p11-p12. The corresponding mouse gene, Recql, was mapped to the telomeric end of mouse chromosome 6 by analysis of DNA from an interspecific cross.

Chromosomal localization of opioid peptide and receptor genes in the mouse

Opiate receptors are the primary targets for the drugs of abuse morphine and heroin. In this study, we completed the localization on mouse chromosomes of the genes encoding mu (Oprm) and kappa (Oprk) receptors, as well as the genes for the opioid propeptides proenkephalin (Penk) and prodynorphin (Pdyn). The genetic mapping was performed using a panel of DNA samples from an interspecific cross [C3H/HeJ-gld and (C3H/HeJ-gld x Mus spretus)F1] that has been characterized for more than 800 markers throughout the genome. The genes are localized on mouse Chr 1 (Oprk, 10 cM from the centromere), Chr 2 (Pdyn, 75 cM from the centromere), Chr 4 (Penk, 1 cM from the centromere) and Chr 10 (Oprm, 10 cM from the centromere). Interestingly, the gene for the mu receptor is located in the same region as a Quantitative Trait Locus for high morphine consumption, thus raising the possibility of its direct role in drug abuse mechanisms.

Mapping of the taurine transporter gene to mouse chromosome 6 and to the short arm of human chromosome 3

Transport proteins have essential functions in the uptake of neurotransmitters and neuromodulators. We have mapped the gene encoding the taurine transporter, Taut, to the central region of mouse chromosome 6. Analysis of a cross segregating the neurological mutant mnd2 excluded Taut as a candidate gene for this closely linked mutation. To map the human taurine transporter gene, TAUT, a sequence-tagged site (STS) corresponding to the 3' untranslated region of the human cDNA was developed. TAUT was assigned to human chromosome 3 by typing this STS on a panel of somatic cell hybrids. Further analysis of a hybrid panel containing defined deletions of chromosome 3 suggested that TAUT maps to 3p21-p25. These data extend a conserved linkage group on mouse chromosome 6 and human chromosome 3p. Deletion of TAUT might contribute to some phenotypic features of the 3p- syndrome.

Human and mouse chromosomal mapping of the myeloid cell leukemia-1 gene: MCL1 maps to human chromosome 1q21, a region that is frequently altered in preneoplastic and neoplastic disease

The MCL1 gene, recently identified in a myeloid leukemia cell line, has sequence similarity to BCL2, the gene at the t(14;18) translocation in follicular lymphoma. The chromosomal location of MCL1 has now been determined. The human locus (MCL1) was mapped to the long arm of human chromosome 1q21, using the methods of in situ hybridization and somatic cell hybrid analysis. In the mouse, MCL1-related sequences were mapped to positions on two mouse chromosomes (chromosomes 3 and 5), using haplotype analysis of an interspecific cross. The location of the locus on mouse chromosome 3 (Mcl1) was homologous to that of MCL1 on human chromosome 1; the second locus (Mcl-rs on mouse chromosome 5) may represent a pseudogene. The proximal long arm of human chromosome 1, where MCL1 is located, is duplicated and/or rearranged in a variety of preneoplastic and neoplastic diseases, including hematologic diseases and solid tumors. MCL1 is thus a candidate gene for involvement in cancer.

Myocyte nuclear factor, a novel winged-helix transcription factor under both developmental and neural regulation in striated myocytes

A sequence motif (CCAC box) within an upstream enhancer region of the human myoglobin gene is essential for transcriptional activity in both cardiac and skeletal muscle. A cDNA clone, myocyte nuclear factor (MNF), was isolated from a murine expression library on the basis of sequence-specific binding to the myoglobin CCAC box motif and was found to encode a novel member of the winged-helix or HNF-3/fork head family of transcription factors. Probes based on this sequence identify two mRNA species that are upregulated during myocyte differentiation, and antibodies raised against recombinant MNF identify proteins of approximately 90, 68, and 65 kDa whose expression is regulated following differentiation of myogenic cells in culture. In addition, the 90-kDa form of MNF is phosphorylated and is upregulated in intact muscles subjected to chronic motor nerve stimulation, a potent stimulus to myoglobin gene regulation. Amino acid residues 280 to 389 of MNF demonstrate 35 to 89% sequence identity to the winged-helix domain from other known members of this family, but MNF is otherwise divergent. A proline-rich amino-terminal region (residues 1 to 206) of MNF functions as a transcriptional activation domain. These studies provide the first evidence that members of the winged-helix family of transcription factors have a role in myogenic differentiation and in remodeling processes of adult muscles that occur in response to physiological stimuli.

Mouse thioredoxin gene maps on chromosome 4, whereas its pseudogene maps on chromosome 1

Thioredoxins are involved in various biochemical systems and mediate both redox and nonredox functions. In mammalian cells, thioredoxin functions as an endogenous glucocorticoid receptor activating factor and as an adult T-cell leukemia-derived factor (ADF) that stimulates expression of interleukin-2 receptor in human T-cell leukemia virus (HTLV)-I transformed T cells. We have mapped the thioredoxin gene (Txn) and its processed pseudogene (Txn-ps1) in the mouse using a panel of interspecific backcross mice. Txn maps to Chr 4, whereas Txn-ps1 maps to the proximal region of Chr 1.

Mapping of the genes encoding mouse thromboxane A2 receptor and prostaglandin E receptor subtypes EP2 and EP3

Thromboxane A2 (TXA2) and prostaglandin E2 (PGE2) are two of the most representative eicosanoids that are formed from arachidonic acid. They produce a broad spectrum of biological effects mediated through specific cell surface receptors. We have mapped genetic loci for TXA2 receptor, Tbxa2r, and for PGE2 receptor subtypes EP2 and EP3, Ptgerep2 and Ptgerep3, respectively, using restriction fragment length variants in interspecific backcross mice. None of the three loci cosegregated with each other. Tbxa2r mapped to Chr 10, Ptgerep2 mapped to the distal end of Chr 3. Possible human loci for these receptors are predicted based on the homology between mouse and human chromosomes.

A glial-specific voltage-sensitive Na channel gene maps close to clustered genes for neuronal isoforms on mouse chromosome 2

A variety of glial cell types express saxitoxin (STX)-binding voltage-sensitive Na channels (1,2), although the possible role of impulse conduction in these cells is not understood. Gautron et al. (1992) recently identified a 7.5 kb species of mRNA in type 1 astrocytes cultured from rat brain cerebrum that hybridized with a "common" Na channel probe but not with brain isoform-specific cDNA probes. Sequence data from cloned cDNAs demonstrate that it encodes a structurally atypical Na channel isoform. We have prepared a cDNA probe specific for a portion of subunit domain IV of the glial channel and mapped the location of the corresponding gene (Scn7a) to mouse chromosome 2. The Scn7a gene mapped 0.9 (+/- 0.9) cM distal to the Gcg locus; the location of the corresponding human gene (SCN7A) is predicted to be in the q36-q37 region of chromosome 2. This site lies just outside a cluster of genes for the brain-specific Na channel isoforms RI, RII and RIII which map proximal to Gcg (17). The presence of at least four genes from two distinct Na channel subfamilies suggests that multiple genetic defects for central and peripheral nervous system disorders ultimately may be linked to this area.

The heat stable antigen (mouse CD24) gene is differentially regulated but has a housekeeping promoter

Expression of the mouse heat stable antigen (HSA or mouse CD24) shows tissue-specific as well as developmental regulation. During the maturation of several hematopoietic lineages, HSA expression is generally high in immature precursor cells and low or absent in terminally differentiated cells. We present evidence suggesting that this regulation of the HSA gene (Cd24a) occurs at the transcriptional level. In addition, sequence and methylation analysis of the Cd24a promoter revealed characteristics of both "housekeeping" and tissue-specific promoters, including a methylation-free, HpaII tiny fragment (HTF) island, multiple putative SP1 and AP-2 consensus binding sites, and a TATA box. Functional analysis of a 0.6-kilobase DNA fragment containing these elements fused to the CAT reporter gene in transient transfection experiments showed activity in both HSA expressing and non-expressing cell lines with a strength similar to that of the herpes-simplex virus-thymidine kinase promoter. Large fragments from the flanking region of the Cd24a promoter did not influence the ubiquitous nature of this promoter. Finally, we mapped the Cd24a, Cd24b, and Cd24c genes to mouse chromosomes 10, 8, and 14 respectively.

A single B1 subunit mapped to mouse chromosome 7 may be a common component of Na channel isoforms from brain, skeletal muscle and heart

A beta 1 subunit associated with one or more isoforms of brain voltage-sensitive Na channels has previously been cloned, sequenced and expressed. Northern and Western blot analyses have suggested that homologues to this protein are expressed in skeletal muscle and heart. Here, reverse transcriptase-polymerase chain reaction (RT-PCR)/cloning reveals that transcripts encoding identical beta 1 subunit ORFs are expressed in adult rat brain, skeletal muscle and heart. Heterologous co-expression of beta 1 with brain (RIIA) and skeletal muscle (mu 1) alpha subunits caused a stabilization of normal, rapidly inactivating (mode 1) gating relative to anomalous, non-inactivating (mode 2) states and a negative shift in steady state inactivation. Chromosome mapping of the beta 1 subunit showed a single locus (Scn1b) in mouse chromosome 7 1.8 cM (+/- 1.2 cM) distal to D19F11S1h and 0.9 cM (+/- 0.9 cM) proximal to Pkca. This locus is in the region of the mouse mutant "quivering," characterized by a variety of neurological disorders and muscle paralysis. A mutation in a single beta 1 subunit forming functional complexes with multiple Na channel isoforms could underlie these deficits.

Physical and linkage mapping of the human and murine genes for the alpha 1 chain of type IX collagen (COL9A1)

Type IX collagen, a member of the FACIT family of extracellular matrix proteins, is a heterotrimer composed of three genetically distinct alpha chains. The cDNAs for the human and mouse alpha 1 (IX) chains have been cloned. In this paper we confirm the mapping of the human COL9A1 gene to chromosome 6q12-q13 by fluorescence in situ hybridization utilizing two genomic clones which also contain short tandem repeat polymorphisms. We also report the characterization of these repeats and their incorporation into the chromosome 6 linkage map. The COL9A1 locus shows no recombination with the marker D6Z1 (Z = 27.61 at theta = O) and identifies the most likely locus order of KRAS1P-[D6Z1-COL9A1]-D6S30. In addition, using an interspecific backcross panel, we have mapped murine Col9a1 to mouse chromosome 1. Together with other comparative mapping results, these data suggest that the pericentric region of human chromosome 6 is homologous to the most proximal segment of mouse chromosome 1. These data may facilitate linkage studies with COL9A1 (or Col9a1) as a candidate gene for hereditary chondrodysplasias and osteoarthritis.

Nucleotide sequence, expression, and chromosomal mapping of Mrp and mapping of five related sequences

We isolated and characterized a genomic clone for the mouse MARCKS-related protein, or MRP, also known as F52 and MacMARCKS. A 3699-bp plasmid contained 407 bp of 5'-flanking region, 186 bp of 5'-untranslated region, 600 bp of protein coding region, 784 bp of a single intron, 746 bp of 3'-untranslated region, and 976 bp of 3'-flanking region. The position of the single intron was identical to the intron position in all known MARCKS mRNAs. When the plasmid containing the genomic sequences was transfected into fibroblasts lacking endogenous Mrp expression, the 407 bp of promoter conferred high-level expression of the full-length, spliced mRNA. The putative promoter was therefore functional; however, despite tissue-specific regulation and transcriptional induction in some cells in a manner similar to that seen with MARCKS expression, the promoters were highly dissimilar at the level of primary sequence (37% identity over 407 bp). Mrp mapped to a position on mouse chromosome 4 that was closely linked to the Lck locus. Numerous additional species that hybridized to the MRP cDNA were noted on Southern blotting of mouse genomic DNA. Five related loci were labeled Mrp-rs1 through Mrp-rs5 (for Mrp-related sequences) and were mapped to mouse chromosomes 10, 17, 15, 13, and X, respectively. Three of these related sequences have been cloned, and all appear to represent pseudogenes.

Chromosomal localization of glutamate receptor genes: relationship to familial amyotrophic lateral sclerosis and other neurological disorders of mice and humans

Receptors for the major excitatory neurotransmitter glutamate may play key roles in neurodegeneration. The mouse Glur-5 gene maps to chromosome 16 between App and Sod-1. The homologous human GLUR5 gene maps to the corresponding region of human chromosome 21, which contains the locus for familial amyotrophic lateral sclerosis. This location, and other features, render GLUR5 a possible candidate gene for familial amyotrophic lateral sclerosis. In addition, dosage imbalance of GLUR5 may have a role in the trisomy 21 (Down syndrome). Further characterization of the murine glutamate receptor family includes mapping of Glur-1 to the same region as neurological mutants spasmodic, shaker-2, tipsy, and vibrator on chromosome 11; Glur-2 near spastic on chromosome 3; Glur-6 near waltzer and Jackson circler on chromosome 10; and Glur-7 near clasper on chromosome 4.

Gene structure, chromosomal localization, and protein sequence of mouse CD53 (Cd53): evidence that the transmembrane 4 superfamily arose by gene duplication

CD53 is a pan-leukocyte surface glycoprotein which spans the plasma membrane four times and is a member of the transmembrane 4 superfamily (TM4SF). The protein sequence and gene structure of mouse CD53 (Cd53) were determined by isolation of both genomic and cDNA clones. CD53 is highly conserved in evolution, as mouse Cd53 was 91% identical to rat CD53 and 82% identical to human CD53. The mouse Cd53 gene spanned approximately 9.0 kb of DNA and encoded the 219 amino acid residues of CD53 over seven exons. The Cd53 gene produced a 1.8 kb transcript which was dramatically upregulated after cell activation. The mouse Cd53 gene was mapped to chromosome 3, whereas the locus of another TM4SF member, CD37 (Cd37), was mapped to mouse chromosome 7. Three lines of evidence suggest that the TM4SF arose divergently from an ancestral gene. First, the gene structure of CD53 was strikingly similar to two other members of the TM4SF, CD63 and TAPA-1; second, Cd37 mapped to the same chromosome as Tapa-1; and, third, Cd37 mapped to a segment of chromosome 7 that contains a number of genes that are structurally or functionally related to genes closely linked to Cd53 on chromosome 3.

A linkage map of mouse chromosome 19: definition of comparative mapping relationships with human chromosomes 10 and 11 including the MEN1 locus

A linkage map of mouse Chromosome (Chr) 19 was constructed using an interspecific cross and markers defined by restriction fragment length variants. The map includes 20 markers, 9 of which had not been mapped previously in the mouse. The data further defined the relationship between genes on mouse Chr 19 and those on the long arm of human Chr 10 and the pericentric region of the long arm of human Chr 11. The comparative mapping analysis suggests that the proximal segment of mouse Chr 19 may contain the MEN1 locus and that the current study has identified additional genes that may be useful for positional cloning of this putative tumor suppressor gene.

Genetic analysis of MRL-lpr mice: relationship of the Fas apoptosis gene to disease manifestations and renal disease-modifying loci

In MRL mice, the mostly recessive lpr mutation results in both the accumulation of CD4-, CD8-, CD3+ T cells in lymphoid tissue and many features of generalized autoimmune disease, including immune complex glomerulonephritis. To positionally clone the lpr mutation and analyze the effects of background genes, backcross offspring were examined from the cross: (MRL/MpJ-lpr x CAST/Ei)F1 x MRL/MpJ-lpr. The lpr gene was found to be closely linked to a mouse chromosome 19 marker defined by a variation of a Fas gene restriction fragment. Our results identified differences in RNA expression and differences in the genomic organization of the Fas gene between normal and lpr mice, and confirm the recent report that a mutation in the Fas apoptosis gene is the lpr mutation. However, our results also indicate that the Fas gene is expressed in spleen cells from normal mice, and spleen and lymph node cells from mice with a second mutation at the lpr locus (lprcg). Together these results suggest that altered Fas transcription results in the failure of lymphocytes to undergo programmed cell death and may lead to an altered immune cell repertoire. This mechanism may explain certain central and peripheral defects in tolerance that are present in autoimmune disease. The current study also demonstrates the profound effect of background genes on the degree of nephritis, lymphadenopathy, and anti-DNA antibody production. Of major note, our studies suggest the identification of chromosomal positions for genes that modify nephritis. Analysis of the backcross mice for markers covering most of the mouse genome suggests that over 50% of the variance in renal disease is attributable to quantitative trait loci on mouse chromosomes 7 and 12. Moreover, this study provides a model for dissecting the complex genetic interactions that result in manifestations of autoimmune disease.

The mouse alpha 1(XII) and human alpha 1(XII)-like collagen genes are localized on mouse chromosome 9 and human chromosome 6

Type XII collagen is a member of the FACIT (fibril-associated collagens with interrupted triple helices) group of extracellular matrix proteins. Like the other members of this group, collagen types IX and XIV, type XII has alternating triple-helical and non-triple-helical domains. Because of its structure, its association with collagen fibrils, and its distribution in dense connective tissues, type XII is thought possibly to act as a cross-bridge between fibrils and resist shear forces caused by tension. A portion of the ffuse gene was isolated by screening a genomic library with a chicken alpha 1 (XII) cDNA probe, followed by subcloning and sequence analysis. Comparison of exon sequences with the sequence of a mouse cDNA clone allowed the mouse gene to be identified as the alpha 1 (XII) collagen gene. In the mouse, Col12a1 is located on chromosome 9, as determined by linkage analysis using DNA from interspecific backcrosses with Mus spretus. Screening of a human genomic library also allowed the isolation of a human alpha 1(XII)-like gene (CoL12A1). This gene was mapped to chromosome 6 by blot hybridization to DNA from human/hamster hybrid cell lines. This information should prove useful in determining the role of type XII collagen genes as candidate genes in inheritable connective tissue diseases.

A linkage map of mouse chromosome 1 using an interspecific cross segregating for the gld autoimmunity mutation

An interspecific backcross was used to define a high resolution linkage map of mouse Chromosome (Chr) 1 and to analyze the segregation of the generalized lymphoproliferative disease (gld) mutation. Mice homozygous for gld have multiple features of autoimmune disease. Analysis of up to 428 progeny from the backcross [(C3H/HeJ-gld x Mus spretus)F1 x C3H/HeJ-gld] established a map that spans 77.6 cM and includes 56 markers distributed over 34 ordered genetic loci. The gld mutation was mapped to a less than 1 cM segment on distal mouse Chr 1 using 357 gld phenotype-positive backcross mice. A second backcross, between the laboratory strains C57BL/6J and SWR/J, was examined to compare recombination frequency between selected markers on mouse Chr 1. Significant differences in crossover frequency were demonstrated between the interspecific backcross and the inbred laboratory cross for the entire interval studied. Sex difference in meiotic crossover frequency was also significant in the laboratory mouse cross. Two linkage groups known to be conserved between segments of mouse Chr 1 and the long arm of human Chrs 1 and 2 where further defined and a new conserved linkage group was identified that includes markers of distal mouse Chr 1 and human Chr 1, bands q32 to q42.

A linkage map of mouse chromosome 8: further definition of homologous linkage relationships between mouse chromosome 8 and human chromosomes 8, 16, and 19

Using an interspecific cross, a mouse chromosome 8 linkage map spanning 72 cM has been defined by the segregation of restriction fragment length variants. Linkage and genetic distance were established for 10 loci by analysis of 114 meiotic events and indicated the following gene order: (centromere)-Insr-3.5 cM-Plat-26.3 cM-Crryps/Mel/Jund-3.5 cM-Junb/Ucp-10.5 cM-Mt-1-27.2 cM-Acta2-0.9 cM-Aprt. These data provide further definition of mouse chromosome 8 linkage relationships and the relationship between segments of this chromosome and human chromosomes 8, 16, and 19.

Stress protein synthesis by crayfish CNS tissue in vitro

Some crustacean axons remain functional for months after injury. This unusual property may require stress proteins synthesized by those neurons or provided to them by glial cells. To begin to explore this hypothesis, we examined the conditions that stimulated stress protein synthesis by crayfish CNS tissue in vitro. Incubation for 1-15 h with arsenite or at temperatures about 15 degrees C higher than the acclimation temperature of 20 degrees C induced transient expression of several stress proteins. The heat stress response was blocked by Actinomycin D, suggesting that synthesis of new mRNA was required. In addition, the major crayfish 66 kD stress protein and its mRNA had sequence identities with the 70 kD stress proteins of mammals. Since the crayfish stress response has much in common with that of other organisms, the unique advantages of the crayfish nervous system can be used to study the impact of stress proteins on glial and neuronal function.

A proximal mouse chromosome 9 linkage map that further defines linkage groups homologous with segments of human chromosomes 11, 15, and 19

A 42-cM map of proximal mouse chromosome 9, including eight loci defined by restriction fragment length variants, has been generated. Linkage was established by haplotype analyses of 114 interspecific backcross mice and indicated the following gene order: (centromere) Pvs-5.3 cM-Icam-1/Ldlr-18.4 cM-Thy-1-1.8 cM-Ncam-0.9 cM-Hexa-7.9 cM-Gsta-7.9 cM-Trf. Three of these loci, Pvs, Icam-1, and Hexa, have not been mapped previously. Together with previous mapping studies the current results suggested that chromosomal segments of mouse chromosomes 7 and 9 and chromosomal segments of human chromosomes 11, 15, and 19 derive from a single putative primordial chromosome. The studies support the postulate that detailed analysis of chromosome organization will be useful in defining events in mammalian evolution.