Differential expression of the mouse mitochondrial genes and the mitochondrial RNA-processing endoribonuclease RNA by androgens.

Using subtractive hybridization to identify genes that are androgen regulated in the mouse epididymis, a number of cDNAs were identified that represented mitochondrial genes including cytochrome oxidase c subunits I, II, and III, cytochrome b, NADH dehydrogenase subunit 5, a region of the displacement loop, and the 16S rRNA. Northern blot analysis of RNA from intact, castrate, or testosterone-replaced epididymides confirmed that these mitochondrial mRNAs as well as the rRNA were androgen regulated with a 2- to 5-fold reduction in expression observed after 4 weeks castration with partial to full recovery to precastrate levels upon 4 weeks of testosterone replacement. In contrast to the mitochondrial genes, the expression of the RNA component of the mitochondrial RNA-processing endoribonuclease (RNAase MRP), a nuclear factor which is thought to be involved in the regulation of mitochondrial DNA synthesis, increased in the epididymis upon castration and then returned to precastrate levels after testosterone replacement. An examination of other androgen-responsive tissues showed that mitochondrial gene expression was also regulated by androgens in the kidney. The RNAase MRP RNA levels, however, showed an increase after castration only in the reproductive tissues (epididymis, vas deferens, and seminal vesicle) and not in the kidney. No correlative increase in mitochondrial DNA levels was observed for any of the tissues. Finally, an analysis of various mouse tissues as well as the different regions of the epididymis revealed large differences in mitochondrial mRNA levels. While for most tissues the mRNA levels correlated with the mitochondrial DNA content, the levels of the RNAase MRP RNA did not. Taken together, these findings not only show the large variations in mitochondrial gene expression between tissues but also demonstrate that the expression of mitochondrial genes and ultimately mitochondrial function are androgen regulated in the epididymis and kidney.     

The pronatriodilatin gene is located on the distal short arm of human chromosome 1 and on mouse chromosome 4.

Atrial natriuretic factors (ANF) are polypeptides having natriuretic, diuretic, and smooth muscle-relaxing activities that are synthesized from a single larger precursor: pronatriodilatin. Chromosomal assignment of the gene coding for human pronatriodilatin was accomplished by in situ hybridization of a [3H]-labeled pronatriodilatin probe to human chromosome preparations and by Southern blot analysis of somatic cell hybrid DNAs with normal and rearranged chromosomes 1. The human pronatriodilatin gene was mapped to the distal short arm of chromosome 1, in band 1p36. Southern blot analysis of mouse X Chinese hamster somatic cell hybrids was used to assign the mouse pronatriodilatin gene to chromosome 4. This assignment adds another locus to the conserved syntenic group of homologous genes located on the distal half of the short arm of human chromosome 1 and on mouse chromosome 4.     

The angiotensinogen gene is located on mouse chromosome 8

We have recently identified a cis-acting genetic lesion affecting angiotensinogen gene expression in testis and salivary gland. Accordingly, the angiotensinogen gene was assigned to mouse chromosome 8 by screening a series of hybrid cell lines for retention of mouse angiotensinogen sequences by genomic Southern analysis. In AKXD recombinant inbred mice, the angiotensinogen gene is 2.4 +/- 1.8 centiMorgan from Rn7S-8,a 7S RNA gene located on chromosome 8 (Taylor, B.A., personal communication). However, the segregation of salivary and testicular angiotensinogen expression phenotypes into inbred mouse strains was not concordant with the known chromosome 8 proviruses Emv-2, Mtv-21, Xmv-12 or Xmv-26.     

The gene cluster for human U2 RNA is located on chromosome 17q21

The gene cluster for human U2 RNA has been mapped to chromosome 17q21 by in situ hybridization and hybridization analysis of DNA from mouse/human somatic cell hybrids.     

The gene coding for the human T-lymphocyte CD2 antigen is located on chromosome 1p

Summary A cDNA clone encoding the human T lymphocyte sheep erythrocyte receptor [the CD2 (T11) antigen] was used as a probe to define the chromosomal location of the gene. The signal, revealed by hybridisation to Southern blots of genomic DNA from somatic cell hybrids, showed a high degree of concordance for human chromosome 1. In particular, the hybrid F4Sc13C19 which contained the short arm only of human chromosome 1 was positive. The location of the CD2 gene to 1p13 was confirmed by in situ hybridisation.     

The mouse immune interferon receptor gene is located on chromosome 10

When mouse L cells are incubated with 32P-labeled recombinant murine immune interferon ( [32P]Mu-IFN-gamma) and subsequently cross-linked with disuccinimidyl suberate, a major complex with an apparent molecular mass of 95,000-125,000 daltons can be visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The complex was not formed when the binding was performed in the presence of excess unlabeled Mu-IFN-gamma or when Chinese hamster ovary cells were used. This complex therefore represents the Mu-IFN-gamma receptor (or its interferon-binding subunit). The chromosomal location of the Mu-IFN-gamma receptor (or the binding subunit of the receptor) gene, termed Ifgr, was identified by performing the binding and cross-linking reactions on a series of mouse-hamster somatic cell hybrids with different subsets of mouse chromosomes. The presence of mouse chromosome 10 was shown to be necessary and sufficient for the formation of the cross-linked complex. Thus, the gene coding for the binding subunit of the Mu-IFN-gamma receptor was localized to mouse chromosome 10. The presence of this chromosome in the hybrid cells was not sufficient, however, to confer antiviral resistance to the hybrids when they were treated with Mu-IFN-gamma and challenged with encephalomyocarditis virus.     

The gene for histone RNA hairpin binding protein is located on human chromosome 4 and encodes a novel type of RNA binding protein.

The hairpin structure at the 3' end of animal histone mRNAs controls histone RNA 3' processing, nucleocytoplasmic transport, translation and stability of histone mRNA. Functionally overlapping, if not identical, proteins binding to the histone RNA hairpin have been identified in nuclear and polysomal extracts. Our own results indicated that these hairpin binding proteins (HBPs) bind their target RNA as monomers and that the resulting ribonucleoprotein complexes are extremely stable. These features prompted us to select for HBP-encoding human cDNAs by RNA-mediated three-hybrid selection in Saccharomyces cerevesiae. Whole cell extract from one selected clone contained a Gal4 fusion protein that interacted with histone hairpin RNA in a sequence- and structure-specific manner similar to a fraction enriched for bovine HBP, indicating that the cDNA encoded HBP. DNA sequence analysis revealed that the coding sequence did not contain any known RNA binding motifs. The HBP gene is composed of eight exons covering 19.5 kb on the short arm of chromosome 4. Translation of the HBP open reading frame in vitro produced a 43 kDa protein with RNA binding specificity identical to murine or bovine HBP. In addition, recombinant HBP expressed in S. cerevisiae was functional in histone pre-mRNA processing, confirming that we have indeed identified the human HBP gene.     

The human apolipoprotein A-II gene is located on chromosome 1

Apolipoprotein (apo) A-II is a major constituent of high density lipoproteins (HDL). The gene for apoA-II has been localized to the p21----qter region of chromosome 1 in man by Southern blot hybridization analysis of DNA from human-mouse cell hybrids using a cloned human apoA-II cDNA probe. The regional assignment was established using two hybrids carrying a reciprocal translocation involving chromosomes 1 and 2. Comparison with previously established gene loci on chromosomes 1 suggests that apoA-II may reside in a conserved linkage group with renin and peptidase C. On the other hand, apoA-II is not linked to the apoA-I gene, which has been localized previously to chromosome 11.     

The human lactase-phlorizin hydrolase gene is located on chromosome 2

The lactase-phlorizin hydrolase gene was assigned to chromosome 2 by analysis of Southern blots of DNA from a panel of human-rodent cell hybrids containing characteristic sets of human chromosomes. The hybridization probe used was a recently isolated cDNA clone of the human lactase-phlorizin hydrolase gene.     

The human natural killer gene complex is located on chromosome 12p12-p13

 Natural killer (NK) cells preferentially express several type II glycoproteins of the calcium-dependent lectin superfamily. The genes coding for these molecules are clustered on the distal mouse chromosome 6 and on the rat chromosome 4 in a region designated the NK gene complex. To date, no definite evidence of the presence of a NK gene complex has been found in humans. Here we report the assignment by fluorescence in situ hybridization of the CD94 gene to human chromosome 12p12-p13, in the same region where the CD69 and NKG2A genes had been previously mapped. In addition, using a yeast artificial chromosome contig spanning this region we determined that the human CD94, NKG2A, NKG2C, NKG2E, and NKR-P1A (NKR) genes map to the short arm of chromosome 12. The distal to proximal position of these loci are: NKR- CD69 - CD94/NKG2A/NKG2C/NKG2E. These data demonstrate the existence of a human NK gene complex located within a 5.6 cM interval flanked by the genetic markers D12S397 and D12S89. The physical distance spanned by the NK gene complex in humans ranges between 0.7 and 2.4 megabases. Received: 17 January 1997 / Revised: 10 March 1997     

The human calcitonin gene is located on the short arm of chromosome 11

By molecular hybridization of human calcitonin cDNA probes to DNA from human-rodent hybrid cells containing identified human chromosomes, we have mapped the human calcitonin gene to the short arm of chromosome 11. This location has been confirmed by in situ hybridization, which further localized the calcitonin gene to region 11p13-15. The significance of this region regarding gene linkage and possible markers for inherited cancers is discussed.     

The gene encoding the mouse T cell differentiation antigen L3T4 is located on chromosome 6

We have used Southern blot analysis of DNA from somatic cell hybrids to map the chromosomal location of the mouse L3T4 T cell differentiation antigen gene to chromosome 6. This finding is of interest because both L3T4 and the alternative T cell differentiation antigen Lyt-2 are homologous to kappa-immunoglobulin light chain-variable regions, and the genes encoding kappa and Lyt-2 are also located on mouse chromosome 6.     

The gene for human complement C9 is on chromosome 5

By hybridizing a cloned cDNA coding for human complement factor C9 to hybrid cells containing subsets of human chromosomes on a rodent background, we have determined that the human gene for C9 is localized on chromosome 5.     

The mouse Cebp gene encoding a DNA-binding protein is polymorphic and is located on chromosome 7

The mouse gene Cebp, encoding the DNA-binding protein C/EBP, has been localized to the proximal region of chromosome 7 by determining the strain distribution patterns of a restriction fragment length polymorphism among the BXD and AKXL recombinant inbred mouse lines.     

The gene encoding the Ia-Associated invariant chain is located on chromosome 18 in the mouse

The chromosomal assignment of the gene encoding the invariant (Ii) chain associated with the mouse immune response antigens (la) was determined by Southern blot analysis of DNA from a panel of mouse x Chinese hamster somatic cell hybrids cleaved with Hind III or Eco RI. Using a mouse Ii cDNA as a hybridization probe, we localized the gene coding for the invariant chain to mouse chromosome 18.     

The second human calcitonin/CGRP gene is located on chromosome 11

Summary A second human calcitonin/calcitonin gene related peptide (hCT/CGRP) gene has been identified. This second hCT/CGRP gene has been shown to contain sequences highly homologous to exons 3, 5 (CGRP-encoding), and 6 of the first hCT/CGRP gene, but sequences closely related to exon 4 (CT-encoding) could not be demonstrated. Southern blot hybridization analysis of DNA from human-rodent somatic cell hybrids showed that the second hCT/CGRP gene is located in the q12-pter region of chromosome 11. The first hCT/CGRP gene has previously been assigned to the p13–p15 region of chromosome 11.     

The gene for the alpha-subunit of retinal rod transducin is on mouse chromosome 9

Mice carrying the autosomal recessive rd gene experience total degeneration of the photoreceptor cells of the retina by 3 to 4 weeks of life. Biochemical studies of the rd retina have demonstrated a lesion in cyclic guanosine monophosphate (cGMP) metabolism due to depressed rod-specific cGMP-phosphodiesterase (cGMP-PDE) activity. The depressed activity could result from, among other things, a lesion in the cGMP-PDE enzyme itself or in any of a number of proteins in the rod that regulate it. We have used a cDNA clone for the alpha-subunit of bovine rod transducin (T alpha 1) to map the corresponding gene, Gnat-1, to mouse chromosome 9 with a panel of Chinese hamster-mouse somatic cell hybrid DNAs. Transducin, a heterotrimeric G protein, is involved in the stimulation of cGMP-PDE when light hits the rod photoreceptors. Since the primary defect in rd disease occurs in a gene(s) on mouse chromosome 5, our results suggest that Gnat-1 is not the rd gene.     

The human mineralocorticoid receptor gene (MLR) is located on chromosome 4 at q31.2

The gene for the human mineralocorticoid receptor (MLR) was previously localized to chromosome 4. Here, we have localized this gene to 4q31.2 by in situ hybridization. This precise mapping of MLR will assist in the linkage analysis and genetic characterization of pseudohypoaldosteronism, an autosomal recessive disorder which likely results from a defect in the MLR gene.     

The gene for human chromogranin A (CgA) is located on chromosome 14

Chromogranin A (CgA) is a protein that is present in most neuroendocrine tissues and is co-secreted with their resident hormones. We have assigned the CgA gene to human chromosome 14 by hybridization of a CgA cDNA probe cloned from a cDNA library of human medullary thyroid carcinoma cells to spots of individual human chromosomes flow-sorted onto nitrocellulose filters. Southern analysis of human genomic DNA with the same probe revealed only 1-3 restriction bands. These studies indicate that the CgA gene is probably single copy and not a member of a dispersed, multigene family. The CgA gene is not co-localized with the genes of any of the CgA-associated hormones.     

The terminal deoxynucleotidyltransferase gene is located on human chromosome 10 (10q23----q24) and on mouse chromosome 19

Terminal deoxynucleotidyltransferase (TdT) is a DNA polymerase expressed in immature lymphocytes of the thymus and bone marrow, as well as certain leukemic cells. Chromosomal assignment of the gene coding for human TdT was accomplished by in situ hybridization of a 3H-labeled cDNA probe to human chromosome preparations and by Southern blot analysis of somatic cell hybrid DNAs. The human TdT gene was mapped to the region q23----q24 of chromosome 10. Breaks at this site have been reported in different translocations in human leukemias. The mouse TdT gene was assigned to chromosome 19 by Southern blot analysis of mouse X Chinese hamster somatic cell hybrids. This result adds a fourth locus to the conserved syntenic group on mouse chromosome 19 and human chromosome 10.