DNA sequence polymorphism in an androgen-regulated gene is associated with alteration in the encoded RNAs

Two isoforms of the kidney androgen-regulated protein are encoded by two alleles of a single gene in OFl mice

Two cDNA clones coding for two forms of the mouse kidney androgen-regulated protein (KAP) distinguished by their electrophoretic mobilities on SDS gel electrophoresis have been isolated from libraries prepared from strains of mice having one (BALB/c) or two (OFl) forms of the KAP protein. The corresponding mRNAs have identical sizes, as well as identical sequences in their 5' non-translated regions. The size difference observed between the two proteins is due to two point mutations in the coding region of the KAP mRNA, leading to two amino-acid changes one of which resulted in the substitution of a glycine for a glutamic acid. As shown byin vitrotranscription/translation experiments, these two amino-acid differences are responsible for the shift in the apparent molecular weight of the protein on SDS gels. Both forms of the protein are more abundant in males than in females.

In vitrotranslation of kidney RNAs isolated from six different strains and species of mice revealed the presence of other forms of the KAP protein, characterized by small variations of their molecular weights. Southern blot analysis data are consistent with the presence of only onekapgene in the mouse genome. A restriction fragment length polymorphism has been observed, which does not correlate with the protein polymorphism, indicating the presence of another allele in the OF1 mouse genome.

Molecular markers near two mouse chromosome 13 genes, muted and pearl, which cause platelet storage pool deficiency (SPD)

The recessive muted (mu) and pearl (pe) mutations on Chromosome (Chr) 13 cause pigment dilution and platelet storage pool deficiency (SPD) in mice. In addition, mu causes inner ear abnormalities and pe has symptoms associated with night blindness. Using an interspecific backcross involving the wild-derived Mus musculus musculus (PWK) stock, we have mapped 33 microsatellite markers and four cDNAs relative to mu, pe, and another recessive mutation, satin (sa). Analyzing a total of 528 backcross offspring, we found tight linkage between the pigment loci and several microsatellite markers (D13Mit87, D13Mit88, D13Mit137 with mu; and D13Mit104, D13Mit160, D13Mit161, and D13Mit169 with pe). These markers should aid the eventual molecular identification of these specific SPD genes.

Molecular map of chromosome 19 including three genes affecting bleeding time: ep, ru, and bm

The mouse ruby eye (ru) and pale ear (ep) pigment dilution genes cause platelet storage pool deficiency (SPD) and prolonged bleeding times. The brachymorphic (bm) gene, in addition to causing skeletal abnormalities, is also associated with prolonged bleeding times. All three hemorrhagic genes are found within 10 cM on Chromosome (Chr) 19. In this study, 15 microsatellite markers and five cDNAs, spanning 21 cM of Chr 19, were mapped in relation to the bm, ep, and ru genes in 457 progeny of an interspecific backcross utilizing the highly inbred strain PWK derived from the Mus musculus musculus species. Several markers were found to be closely linked to the three genes and should be useful as entry points in their eventual molecular identification.

Nonrandom duplication of the chromosome bearing a mutated Ha-ras-1 allele in mouse skin tumors

We analyzed the normal/mutated allelic ratio of the Ha-ras-1 gene in mouse skin squamous cell carcinomas induced by initiation with dimethylbenz[a]anthracene and promotion with phorbol 12-myristate 13-acetate. DNA for these studies was obtained from short-term tumor cultures (24-72 hr) to eliminate the contribution of stromal and inflammatory cells to the sample. The allelotypic analysis was performed in 25 squamous cell carcinomas by quantitative radio-analysis of the Xba I restriction fragment length polymorphism as detected by BS9, a v-Ha-ras probe, and rehybridization of the Southern blots with probes for chromosomes 7 and 8. Approximately 85% of the tumors presented overrepresentation of the mutated allele in the form of 1 normal/2 mutated (12 tumors), 0 normal/3 mutated (4 tumors), 0 normal/2 mutated (3 tumors), and gene amplification (3 tumors). No tumor was found with a 2 normal/1 mutated allelic ratio. These results support our previous cytogenetic studies, indicating that trisomy of chromosome 7 is present in the majority of these tumors and show that nonrandom duplication of the chromosome carrying the mutated Ha-ras-1 allele appears to be a major mechanism by which the mutated gene is overrepresented.

Effects of S-adenosyl-1,8-diamino-3-thio-octane and S-methyl-5'-methylthioadenosine on polyamine synthesis in Ehrlich ascites-tumour cells

The rate-limiting enzymes in polyamine biosynthesis, ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (AdoMetDC), are negatively regulated by the polyamines spermidine and spermine. In the present work the spermidine synthase inhibitor S-adenosyl-1,8-diamino-3-thio-octane (AdoDATO) and the spermine synthase inhibitor S-methyl-5'-methylthioadenosine (MMTA) were used to evaluate the regulatory role of the individual polyamines. Treatment of Ehrlich ascites-tumour cells with AdoDATO caused a marked decrease in spermidine content together with an accumulation of putrescine and spermine. Treatment with MMTA, on the other hand, gave rise to a marked decrease in spermine, with a simultaneous accumulation of spermidine. A dramatic increase in the activity of AdoMetDC, but not of ODC, was observed in MMTA-treated cells. This increase appears to be unrelated to the decrease in spermine content, because a similar rise in AdoMetDC activity was obtained when AdoDATO was given in addition to MMTA, in which case the spermine content remained largely unchanged. Instead, we show that the increase in AdoMetDC activity is mainly due to stabilization of the enzyme, probably by binding of MMTA. Treatment with AdoDATO had no effects on the activities of ODC and AdoMetDC, even though it caused a precipitous decrease in spermidine content. The expected decrease in spermidine-mediated suppression of ODC and AdoMetDC was most probably counteracted by the simultaneous increase in spermine. The combination of AdoDATO and MMTA caused a transient rise in ODC activity. Concomitant with this rise, the putrescine and spermidine contents increased, whereas that of spermine remained virtually unchanged. The increase in ODC activity was due to increased synthesis of the enzyme. There were no major effects on the amount of AdoMetDC mRNA by treatment with the inhibitors, alone or in combination. However, the synthesis of AdoMetDC was slightly stimulated in cells treated with MMTA or AdoDATO plus MMTA. The present study demonstrates that regulation of neither ODC nor AdoMetDC is a direct function of the polyamine structure. Instead, it appears that the biosynthesis of the polyamines is feedback-regulated by the various polyamines at many different levels.

Molecular genetics of androgen-inducible RP2 gene transcription in the mouse kidney

Androgen control of the RP2 gene in the mouse kidney has been modified during evolution. In inbred mice (Mus domesticus), the concentrations of mRNAs encoded by RP2 undergo a 10- to 12-fold induction in response to testosterone; in other Mus species (e.g., Mus hortulanus and Mus caroli), induction ranges from none to about two- to fourfold. In this communication, we show that androgens induced RP2 transcription in M. domesticus, although this induction may not have fully accounted for the increase in mRNA levels. Reduced mRNA inducibility in M. hortulanus and in several other species was associated with an absence of transcriptional induction. Analysis of an interspecies backcross population indicated that the difference in RP2 inducibility between M. domesticus and M. hortulanus was due to a single Mendelian locus tightly linked (0 of 47 recombinants) to RP2. The RP2 gene was found to contain at least two promoters, only one of which was highly sensitive to testosterone. These results indicate that induction of the RP2 mRNAs, as well as interspecies variations in RP2 inducibility, are primarily a consequence of effects on this promoter.

Chromosomal location of the gene encoding the murine acute-phase protein serum amyloid P-component (SAP)

A full-length cDNA clone, pmSAP3, encoding, the serum P component (SAP), has been used to search for DNA fragment length variation among mouse strains previously analyzed for differences in endogenous SAP levels. Three alleles were found using EcoRI-digested DNA. The finding of a single 5.4-kb fragment, allele d, in DNA from DBA/2J mice suggests the presence of a single Sap locus. Segregation of DNA fragment associated with Sapb and Sapd alleles was analyzed in three sets of recombinant inbred (RI) strains. The strain distribution pattern found for the Sap alleles was identical to that of alleles of Ly-9 in 43 individual RI strains, suggesting tight linkage with Ly-9 on mouse chromosome 1. In the BXD RI strains, the SDP of the Sap locus, defined by the difference in the endogenous SAP level, is also identical to the SDP of the DNA fragments. We propose to redesignate the Sap locus to include both the structural element defined by the DNA polymorphism and the regulatory element involved in the regulation of SAP synthesis. The Sap locus is the major genetic element contributing to the regulation of SAP production. Other genetic factors are also involved, as shown by the presence of nonparental phenotypes in the individual BXH RI strains.

The tumor-rejection antigens of the 1591 ultraviolet fibrosarcoma. Potential origin and evolutionary implications

Previously, we cloned and sequenced the three novel MHC class I genes expressed by the C3H UV fibrosarcoma, 1591. We have extended the analysis of the polymorphic nature of these genes relative to the C3H strain. Scattered nucleotide differences among the tumor genes as compared with the C3H H-2 and Qa sequences make it highly unlikely that the novel tumor genes were generated by recombination between endogenous C3H sequences. Given that two of the tumor clones, A149 and A166, are remarkably similar in amino acid and DNA sequence to H-2Lq and H-2Dq, respectively, we also examined the 1591 RP2 and GUS loci for evidence of polymorphism. Compared with C3H and B10.AKM, 1591 appears to be heterozygous at each of these loci, consistent with an H-2q origin for the two novel 1591 class I genes. Interestingly, the third tumor gene, designated A216, shares certain characteristics with the H-2Ks antigen, reminiscent of the naturally occurring combination of H-2Ks, H-2Dq, and H-2Lq antigens found in some Swiss mouse strains. As a result, we propose that the non-C3H/HeN characteristics displayed by the 1591 tumor point to a non-C3H origin for the novel tumor class I genes of 1591.

Feedback control of ornithine decarboxylase expression by polyamines. Analysis of ornithine decarboxylase mRNA distribution in polysome profiles and of translation of this mRNA in vitro

Cell growth and differentiation require the presence of optimal concentrations of polyamines. Ornithine decarboxylase (ODC) catalyses the first and rate-controlling step in polyamine synthesis. In studies using cultures of Ehrlich ascites-tumour cells, we have shown that the expression of ODC is subject to feedback regulation by the polyamines. A decrease in the cellular polyamine concentration results in a compensatory increase in the synthesis of ODC, whereas an increase in polyamine concentration results in suppression of ODC synthesis. These changes in ODC synthesis were attributed to changes in the efficiency of ODC mRNA translation, because the steady-state amount of ODC mRNA remained constant. We now show that the number of ribosomes associated with ODC mRNA is low, and that the increase in ODC mRNA translation takes place without a shift in the distribution of ODC mRNA towards larger polysomes. This finding indicates that the polyamines regulate the efficiency of ODC mRNA translation by co-ordinately affecting the rates of initiation and elongation. By analysing ODC mRNA translation in vitro, using a rabbit reticulocyte lysate, polyadenylated RNA from a cell line with an amplified ODC gene, and a monospecific anti-ODC antibody, we also show that spermidine, but not putrescine, exerts a direct regulatory effect on ODC synthesis.

Molecular genetics of androgen-inducible RP2 gene transcription in the mouse kidney

Androgen control of the RP2 gene in the mouse kidney has been modified during evolution. In inbred mice (Mus domesticus), the concentrations of mRNAs encoded by RP2 undergo a 10- to 12-fold induction in response to testosterone; in other Mus species (e.g., Mus hortulanus and Mus caroli), induction ranges from none to about two- to fourfold. In this communication, we show that androgens induced RP2 transcription in M. domesticus, although this induction may not have fully accounted for the increase in mRNA levels. Reduced mRNA inducibility in M. hortulanus and in several other species was associated with an absence of transcriptional induction. Analysis of an interspecies backcross population indicated that the difference in RP2 inducibility between M. domesticus and M. hortulanus was due to a single Mendelian locus tightly linked (0 of 47 recombinants) to RP2. The RP2 gene was found to contain at least two promoters, only one of which was highly sensitive to testosterone. These results indicate that induction of the RP2 mRNAs, as well as interspecies variations in RP2 inducibility, are primarily a consequence of effects on this promoter.

Mapping and gene order of U1 small nuclear RNA, endogenous viral env sequence, amylase, and alcohol dehydrogenase-3 on mouse chromosome 3

Linkage was established between a number of genes that map on chromosome 3 by studying the distribution patterns of DNA polymorphisms and protein electrophoretic mobility polymorphisms in recombinant inbred (RI) strains of mice. This analysis resulted in the following suggested gene order between the newly assigned genes and previously mapped genes: gamma-fibrinogen (Fgg), Xmmv-22 of mink cell focus-inducing (MCF) virus, U1b small nuclear RNA gene cluster (Rnu-1b), amylase (Amy-1,2), cadmium resistance (cdm), alcohol dehydrogenase-3 (Adh-3), alcohol dehydrogenase-1 (Adh-1). In situ hybridization to chromosome spreads confirmed the assignment of the Ulb small nuclear RNA (snRNA) gene cluster and the gamma-fibrinogen gene to the center of chromosome 3.

Analysis of the mouse Amy locus in recombinant inbred mouse strains

Pancreatic and salivary amylase cDNA probes have been used to search for new DNA fragment length variation among a total of 43 inbred mouse strains. Fragment length differences found with three restriction endonucleases grouped the strains into two major classes. The segregation of these variant fragments has been analyzed among several sets of recombinant inbred strains and is presented here. Previously reported differences for strains YBR and CE have been confirmed. New segregation data for carbonic anhydrase, a locus near the proximal end of mouse chromosome 3, are presented.

Polymorphism in an androgen-regulated mouse gene is the result of the insertion of a B1 repetitive element into the transcription unit

The single-copy RP2 gene in mice produces three major mRNAs, the abundances of which are significantly increased in the kidneys by the administration of testosterone. S1 nuclease analysis of the kidney mRNAs indicated that they differ in the lengths of their 3' untranslated regions as a result of the use of different polyadenylation sites. When the mRNAs from different inbred mouse strains were examined by Northern blot analysis, it was observed that the largest mRNA varies in size, whereas the sizes of the other mRNAs remain the same. In DBA/LiHa and DBA/2J mice, the largest mRNA is approximately 2,150 nucleotides long, whereas the corresponding mRNA in C57BL/6J and BALB/cJ mice is only 1,950 nucleotides in length. All of these strains also have RP2 mRNAs that are 1,450 and 1,350 nucleotides long. By S1 nuclease mapping and comparison of the sequence of cDNA clones representing these mRNAs in DBA/LiHa and C57BL/6J mice, we determined that this size difference or polymorphism observed in the largest mRNA is the result of the insertion of a member of the B1 family of repeats into the 3' untranslated region of the RP2 gene in DBA mice. This particular B1 repeat is transcribed by RNA polymerase III in vitro, and its transcriptional orientation is opposite to that of the RP2 transcript. The polymorphism described here is evidence for the mobility of B1 repetitive elements within the genome.

Genetic analysis of a mouse t complex locus that is homologous to a kidney cDNA clone

A mouse kidney cDNA clone, pMK174, identifies restriction fragment length polymorphisms (RFLPs) that map to two unlinked loci. One, designated D17Rp17, has been mapped near quaking, (qk), on chromosome 17 using three sets of recombinant inbred (RI) strains. A study of several t haplotypes resulted in the identification of t-specific alleles of D17Rp17 that map to the proximal half of the t complex. Neither t-specific nor wild-type D17Rp17 alleles are present in chromosomes carrying either the T Orleans (TtOrl) or the T hairpin tail (Thp) deletions. Comparison with other molecular markers indicates that pMK174 identifies a new proximal t complex locus, Rp17. The second locus identified by pMK174, termed D4Rp18, is tentatively assigned to chromosome 4 by mouse-Chinese hamster somatic cell hybrid analysis.

A genetic locus closely linked to a protease inhibitor gene complex controls the level of multiple RNA transcripts

The two major protease inhibitors in mouse plasma are alpha 1-protease inhibitor (alpha 1-PI), putative inhibitor of neutrophil elastase, and contrapsin, an inhibitor in vitro of trypsinlike proteases. We have shown by nucleotide sequence analysis that these two inhibitors are related (R. E. Hill, P. H. Shaw, P. A. Boyd, H. Baumann, and N. D. Hastie, Nature (London) 311:175-177, 1984). Here, we show that the contrapsin and alpha 1-PI genes are members of two different multigene families, each containing at least three genes in mice and rats. We established the chromosomal locations of these genes by analyzing the segregation of restriction fragment length polymorphisms in recombinant inbred mouse strains. These experiments show that the multiple genes in each family are clustered and that the two gene families are closely linked on chromosome 12. Thus the genes for contrapsin and alpha 1-PI are likely to have evolved by duplication of a common ancestral gene. The contrapsin multigene family codes for multiple mRNA transcripts in the liver. There is a genetic difference among inbred mouse strains in the regulation of two of these transcripts. In some inbred strains the transcripts are synthesized constitutively; in others they are induced by inflammation. We mapped in recombinant inbred strains the regulatory locus responsible for this genetic variation and found it is linked to the contrapsin multigene family, which suggests a cis-acting regulatory element. We also found that the contrapsin and the alpha 1-PI multigene families have acquired very different regulatory responses since the time of the gene duplication event.

Translational regulation of ornithine decarboxylase by polyamines

The activity of ornithine decarboxylase (ODC), the first and rate-limiting enzyme in the polyamine biosynthetic pathway, is dramatically increased in proliferating cells. In addition to transcriptional regulation of ODC, the present study shows that the enzyme is regulated at the translational level by putrescine and spermidine. ODC synthesis is inhibited by an increase and stimulated by a decrease in their cellular content. Spermidine is a more potent negative regulator than is putrescine. The effects of polyamines on ODC synthesis were not attributable to changes in the cellular content of ODC mRNA, thus demonstrating regulation at the translational level.

Amino acid sequence of the testosterone-regulated mouse kidney RP2 protein deduced from its complementary DNA sequence

The major forms of testosterone-regulated RP2 messenger RNA (also known as MAK mRNA and pMK908) in the mouse kidney were characterized by examining cDNA and genomic clones. Three sizes of RP2 mRNA are detected by Northern blot analysis and these were shown to result from polyadenylation at three distinct sites within the primary transcript of this single-copy gene. The complete RP2 mRNA sequence was obtained from overlapping cDNA clones, revealing an open reading frame of 357 amino acids that corresponds to a protein of 40,365 daltons. The detection of RP2 mRNA in all tissues examined to date suggests that the RP2 protein may function in a housekeeping role in all cells. This is supported by the finding of a high percentage of G + C residues at the 5' end of the gene, including a sequence homologous to the binding site of the transcription factor Sp1, which has been suggested to affect the regulation of other housekeeping genes that have been characterized. An examination of the amino acid sequence indicates that the RP2 protein is proline-rich and is composed of alternating alpha-helix and beta-sheet regions. RP2 is probably not integrated into a membrane structure in the cell as it does not appear to contain hydrophobic regions capable of spanning a membrane.

Polymorphism in an androgen-regulated mouse gene is the result of the insertion of a B1 repetitive element into the transcription unit

The single-copy RP2 gene in mice produces three major mRNAs, the abundances of which are significantly increased in the kidneys by the administration of testosterone. S1 nuclease analysis of the kidney mRNAs indicated that they differ in the lengths of their 3' untranslated regions as a result of the use of different polyadenylation sites. When the mRNAs from different inbred mouse strains were examined by Northern blot analysis, it was observed that the largest mRNA varies in size, whereas the sizes of the other mRNAs remain the same. In DBA/LiHa and DBA/2J mice, the largest mRNA is approximately 2,150 nucleotides long, whereas the corresponding mRNA in C57BL/6J and BALB/cJ mice is only 1,950 nucleotides in length. All of these strains also have RP2 mRNAs that are 1,450 and 1,350 nucleotides long. By S1 nuclease mapping and comparison of the sequence of cDNA clones representing these mRNAs in DBA/LiHa and C57BL/6J mice, we determined that this size difference or polymorphism observed in the largest mRNA is the result of the insertion of a member of the B1 family of repeats into the 3' untranslated region of the RP2 gene in DBA mice. This particular B1 repeat is transcribed by RNA polymerase III in vitro, and its transcriptional orientation is opposite to that of the RP2 transcript. The polymorphism described here is evidence for the mobility of B1 repetitive elements within the genome.

Linkage of genes for laminin B1 and B2 subunits on chromosome 1 in mouse

We have used cDNA clones for the B1 and B2 subunits of laminin to find restriction fragment length DNA polymorphisms for the genes encoding these polypeptides in the mouse. Three alleles were found for LamB2 and two for LamB1 among the inbred mouse strains. The segregation of these polymorphisms among recombinant inbred strains showed that these genes are tightly linked in the central region of mouse Chromosome 1 between Sas-1 and Ly-m22, 7.4 +/- 3.2 cM distal to the Pep-3 locus. There is no evidence in the mouse for pseudogenes for these proteins.

A genetic locus closely linked to a protease inhibitor gene complex controls the level of multiple RNA transcripts

The two major protease inhibitors in mouse plasma are alpha 1-protease inhibitor (alpha 1-PI), putative inhibitor of neutrophil elastase, and contrapsin, an inhibitor in vitro of trypsinlike proteases. We have shown by nucleotide sequence analysis that these two inhibitors are related (R. E. Hill, P. H. Shaw, P. A. Boyd, H. Baumann, and N. D. Hastie, Nature (London) 311:175-177, 1984). Here, we show that the contrapsin and alpha 1-PI genes are members of two different multigene families, each containing at least three genes in mice and rats. We established the chromosomal locations of these genes by analyzing the segregation of restriction fragment length polymorphisms in recombinant inbred mouse strains. These experiments show that the multiple genes in each family are clustered and that the two gene families are closely linked on chromosome 12. Thus the genes for contrapsin and alpha 1-PI are likely to have evolved by duplication of a common ancestral gene. The contrapsin multigene family codes for multiple mRNA transcripts in the liver. There is a genetic difference among inbred mouse strains in the regulation of two of these transcripts. In some inbred strains the transcripts are synthesized constitutively; in others they are induced by inflammation. We mapped in recombinant inbred strains the regulatory locus responsible for this genetic variation and found it is linked to the contrapsin multigene family, which suggests a cis-acting regulatory element. We also found that the contrapsin and the alpha 1-PI multigene families have acquired very different regulatory responses since the time of the gene duplication event.