Properties of rat and mouse beta-glucuronidase mRNA and cDNA, including evidence for sequence polymorphism and genetic regulation of mRNA levels

Characterization of the oligosaccharide component of microsomal beta-glucuronidase from rat liver

The oligosaccharides of microsomal beta-glucuronidase were analysed by gel permeation and weak anion exchange chromatography following hydrazine release. N-linked glycans, constituted 80% of the total glycan pool and were mainly of the tri- and biantennary complex type with or without core and arm fucose. The major oligosaccharide, that comprised 30.6% of all the species analysed, was structurally identified by reagent array analysis method and found to be a triantennary complex structure, Galbeta1,4GlcNAcbeta1,2Manalpha1,6(3)(Galbeta1,4GlcNAcbeta1,4(Galbeta1,4GlcNAcbeta1,2) Manalpha1,3(6))Manbeta1,4GlcNAcbeta1,4 GlcNAc. O-Linked glycans comprised 20% of the total glycan pool, the major species being Galbeta1,3GalNAc. All of the N- and O-linked glycans were charged. Most of the negative charge was due to sialic acid (85.0%) with the remainder being phosphate present as phosphomonoesters (7.3%) and phosphodiesters (5%). This is the first report of O-linked carbohydrate chains in microsomal beta-glucuronidase. The presence of O-linked glycans and branched N-linked glycans in a microsomal enzyme, in relation to the current view of glycosyltransferase compartmentalization in the Golgi is discussed.

Growth hormone and insulin-like growth factor-I enhance beta-glucuronidase gene activation by androgen in mouse kidney

Beta-glucuronidase (GUS) is a lysosomal enzyme that, in mouse kidney, is subject to control by multiple hormones: androgen, which increases GUS transcription; estrogen, which antagonizes androgen-mediated stimulation of GUS; and growth hormone (GH), which appears to be necessary for the full androgen effect. Neither estrogen nor GH affects GUS in the absence of androgen. In hypophysectomized or pituitary dwarf mice the reduced androgen stimulation of GUS can be partially restored with GH treatment. Androgen-induced GUS mRNA increased significantly with intermittent GH, compared to no GH or continuous GH. Intact mice subjected to continuous infusion of GH showed a depressed androgen effect on GUS similar to that seen in GH-deficient mice. Thus, pulsatile GH is required for the full androgen response. Insulin-like growth factor-I (IGF-I) also restored GUS induction by androgen in GH-deficient mice. We conclude that GH enhances the effect of androgen on the GUS gene via IGF-I. Using transgenic mice, we have also identified a genetic variant of the GUS gene that is insensitive to GH enhancement of the androgen effect.

The androgen-dependent mouse seminal vesicle secretory protein of 99 amino acids (MSVSP99): regulation of the mRNA and preliminary characterization of the promoter

MSVSP99 (mouse seminal vesicle secretory protein of 99 amino acids) is a member of the rat and mouse seminal vesicle secretory protein (SVS) family. In order to characterize its androgenic regulation, the cloned cDNA and gene encoding MSVSP99 have been used. At adulthood, the MSVSP99 mRNA represents from 3 to 7% of the total mRNA population. This mRNA accumulation is under androgenic control because it is abolished by castration and restored in castrated mice by heptylate testosterone injection. During ontogenesis, MSVSP99 mRNA is just detectable in 10-day-old mice, and reaches adult levels at 30 days. Neonatal castration abolishes MSVSP99 mRNA accumulation in 20-day-old mice. Transcription elongation assays show that androgens act mainly on the MSVSP99 gene transcription. In an attempt to obtain information about the mechanism of androgen action on transcription, preliminary transient transfection experiments in CV-1 cells permitted us to define a promoter region (-387/ + 16), the activity of which is enhanced by dihydrotestosterone.

Murine mucopolysaccharidosis type VII: long term therapeutic effects of enzyme replacement and enzyme replacement followed by bone marrow transplantation

We demonstrated previously that short term administration of recombinant beta-glucuronidase to newborn mice with mucopolysaccharidosis type VII reduced lysosomal storage in many tissues. Lysosomal storage accumulated gradually after cessation of enzyme replacement therapy. Mice alive at 1 yr of age had decreased bone deformities and less lysosomal storage in cortical neurons. Here we compare the effects of long term enzyme replacement initiated either at birth or at 6 wk of age, and of enzyme administration initiated at birth followed by syngeneic bone marrow transplantation (BMT) at 5 wk of age. Several mice from each treatment group lived to at least 1 yr of age. Liver and spleen samples had beta-glucuronidase levels ranging from 2.4 to 19.8% of normal and showed a parallel decrease in lysosomal storage. The combination of enzyme replacement therapy followed by BMT reduced lysosomal distension in meninges, corneal fibroblasts, and bone when compared with treatment with enzyme alone. Mice treated at birth had less lysosomal storage in some neurons of the brain and the skeletal dysplasia was less severe when compared to mice whose treatment was delayed until 6 wk of age. We conclude that both enzyme replacement alone and early enzyme replacement followed by BMT have long term positive effects on murine mucopolysaccharidosis type VII. In addition, treatment started at birth is far more effective than treatment initiated in young adults.

Enzyme replacement therapy for murine mucopolysaccharidosis type VII

Recombinant mouse beta-glucuronidase administered intravenously to newborn mice with mucopolysaccharidosis type VII (MPS VII) is rapidly cleared from the circulation and localized in many tissues. Here we determine the tissue distribution of injected enzyme and describe its effects on the histopathology in 6-wk-old MPS VII mice that received either one injection of 28,000 U recombinant beta-glucuronidase at 5 wk of age or received six injections of 28,000 U given at weekly intervals beginning at birth. These mice were compared with untreated 6-wk-old MPS VII mice. The single injection decreased lysosomal distention in the fixed tissue macrophage system. MPS VII mice that received multiple injections had 27.8, 3.5, and 3.3% of normal levels of beta-glucuronidase in liver, spleen, and kidney, respectively. Brain had detectable beta-glucuronidase, ranging from 2.0-12.1% of normal. Secondary elevations of alpha-galactosidase and beta-hexosaminidase in brain, spleen, liver, and kidney were decreased compared with untreated MPS VII mice. Although no improvement was observed in chondrocytes, glia, and some neurons, the skeleton had less clinical and pathological evidence of disease and the brain had reduced lysosomal storage in meninges and selected neuronal groups. These data show that recombinant beta-glucuronidase treatment begun in newborn MPS VII mice provides enzyme to most tissues and significantly reduces or prevents the accumulation of lysosomal storage during the first 6 wk of life. Whether therapy begun later in life can achieve this level of correction remains to be established.

Obesity-induced diabetes (diabesity) in C57BL/KsJ mice produces aberrant trans-regulation of sex steroid sulfotransferase genes

The diabetes (db) gene is a recessive obesity mutation in the mouse capable of producing diabetes only through interaction with heretofore undefined modifiers in the genetic background of certain inbred strains. Here we identify the genetic map locations of androgen and estrogen sulfotransferase genes important in maintaining the balance of active sex steroids in the liver. The Std locus encoding dehydroepiandrosterone sulfotransferase was mapped to proximal Chromosome 7, and the Ste locus encoding estrogen sulfotransferase was mapped to Chromosome 5. The db mutation in the diabetes-susceptible C57BL/KsJ strain aberrantly regulated mRNA transcript levels from these two loci. Hepatic Ste mRNA transcripts were increased from undetectable levels in normal males and females to high levels in db/db mice of both sexes. An anomalous suppression of Std transcription was observed in db/db females, but not in normal females. These reciprocal changes in mRNA concentrations in mutant females were reflected by an induction of a high affinity estrogen sulfotransferase activity and a concomitant loss of dehydroepiandrosterone sulfotransferase activity. These db gene-elicited effects were specific for the sex steroid sulfotransferases since other potential sex steroid metabolizing enzymes (phenol sulfotransferase, sex steroid sulfohydrolase, and UDP-glucuronyltransferase) were unaffected. These aberrant changes would virilize hepatic metabolism in females by increasing the ratio of active androgens to estrogens. In human females, non-insulin-dependent diabetes mellitus often develops when visceral obesity and hyperinsulinemia are associated with hyperandrogenization. This study demonstrates that background modifier genes interacting deleteriously with an obesity mutation are not necessarily defective alleles. Rather, some are functional genes whose regulation has been altered by pleiotropic effects of the obesity gene.

The Gus-e locus regulates estrogen repression of androgen-induced beta-glucuronidase expression in mouse kidney

Both enzyme activity and mRNA concentration of beta-glucuronidase were measured in kidneys of mice treated with testosterone and the synthetic estrogen, diethylstilbestrol. Six congenic strains, all having a C57BL6/J genetic background but each having a different haplotype of the beta-glucuronidase gene complex, were compared. In each strain the induction caused by androgen was partially repressed by estrogen. The extent of this antagonism varied among the six haplotypes and was not coordinate with the extent of induction by androgen alone. Antagonism appears to be regulated by at least two alleles of a new locus, Gus-e, within the beta-glucuronidase gene complex. Repression by estrogen, like induction by androgen, appears to take place primarily at the transcriptional level. Kinetic studies revealed that estrogen causes the androgen response curve to plateau earlier and at a lower level. This suggests that estrogen increases the rate of gene deactivation rather than decreasing the rate of gene activation. Isoelectric focusing of beta-glucuronidase from Gus-ea and Gus-eb mice and their F1 progeny revealed that the genes are regulated in cis. Together, these findings support a model in which both sex hormones exert their effects on separate DNA response elements located in close proximity to the gene or within the gene itself.

Estradiol regulates class I alcohol dehydrogenase gene expression in renal medulla of male rats by a post-transcriptional mechanism

Rat kidney contains alcohol dehydrogenase (ADH) activity which appears to be identical to the class I ADH expressed in liver. Treatment of male rats with estradiol for 10 days induced ADH activity and protein in the kidney approximately 3-fold. This was not the result of suppression of testosterone levels by estrogen, as castration did not increase ADH activity. In situ hybridization of kidney sections showed that ADH transcripts were localized to the medulla, that the basal level of mRNA is very low in the male, and that the induction of ADH mRNA by estradiol was approximately 10-fold. As estimated from Northern blot analysis, the induction of the mRNA was approximately 7-fold. Thus, induction of ADH mRNA substantially exceeded the increase of ADH activity and protein. Since the estradiol-treated rats lost weight relative to the oil-injected controls, the effect of starvation on ADH mRNA in kidney was examined. Starvation decreased kidney ADH activity by about 30% but increased mRNA about 2-fold. Time course experiments demonstrated induction of ADH mRNA by estradiol within 1 h with the maximum level achieved by 24 h. The transcription rate of the ADH gene as assessed by nuclear run-on assays performed at 1 and 24 h after treatment with estradiol was unchanged. We conclude that estradiol induces ADH mRNA in kidney by a post-transcriptional mechanism.

Modulation of androgen-responsive gene expression by estrogen

Studies on hormonal action frequently focus on a single hormone. In intact animals, however, genes may respond to the balance of multiple hormones. Therefore, we have studied the mutual influence of sex steroids on eight genes previously known to be testosterone-responsive in kidneys of mice. A variety of responses to estrogen were recorded. Effects occurred primarily at the transcriptional level although in several cases there was also evidence of decreased mRNA stability. Estrogen did not affect the nuclear location of the androgen receptor. Apparently each gene interacts with both androgen-receptor complex and estrogen-receptor complex, and the ultimate outcome depends on each gene's detailed regulatory structure.

The recombinant congenic strains--a novel genetic tool applied to the study of colon tumor development in the mouse

The development of tumors in mice is under multigenic control, but, in spite of considerable efforts, the identification of the genes involved has so far been unsuccessful, because of the insufficient resolution power of the available genetic tools. Therefore, a novel genetic tool, the RC (Recombinant Congenic) strains system, was designed. In this system, a series of RC strains is produced from two inbred strains, a "background" strain and a "donor" strain. Each RC strain contains a different small subset of genes from the donor strain and the majority of genes from the background strain. As a consequence, the individual genes of the donor strain which are involved in the genetic control of a multigenic trait, become separated into different RC strains, where they can be identified and studied individually. One of the RC strains series which we produced is made from the parental strains BALB/cHeA (background strain) and STS/A (donor strain). We describe the genetic composition of this BALB/cHeA-C-STS/A (CcS/Dem) series and show, using 45 genetic autosomal markers, that it does not deviate from the theoretical expectation. We studied the usefulness of the CcS/Dem RC strains for analysis of the genetics of colon tumor development. The two parental strains, BALB/cHeA and STS/A, are relatively resistant and highly susceptible, respectively, to the induction of colon tumors by 1,2-dimethylhydrazine (DMH). The individual RC strains differ widely in colon tumor development after DMH treatment; some are highly susceptible, while others are very resistant. This indicates that a limited number of genes with a major effect are responsible for the high susceptibility of the STS strain. Consequently, these genes can be mapped by further analysis of the susceptible RC strains. The differences between the RC strains were not limited to the number of tumors, but the RC strains differed also in size of the tumors and the relative susceptibility of the two sexes. Our data indicate that the number of tumors and the size of tumors are not controlled by the same genes. The genetics of these different aspects of colon tumorigenesis can also be studied by the RC strains. The DMH-treated mice of the parental strains and the RC strains also developed anal tumors and haemangiomas in varying numbers. The strain distribution pattern (SDP) of susceptibility for each of the three types of tumors induced by DMH is different, indicating that development of these tumors is under control of different, largely non-overlapping, sets of genes.(ABSTRACT TRUNCATED AT 400 WORDS)

Estradiol induces class I alcohol dehydrogenase activity and mRNA in kidney of female rats

Rat kidney contains alcohol dehydrogenase (ADH) activity which appears to be similar or identical to the class I ADH expressed in liver. Both tissues contain a 1.6-kb transcript which hybridizes with an ADH cDNA under stringent conditions. Kidney ADH activity is responsive to estradiol. The enzyme activity in the kidneys of sham-operated and ovariectomized animals was the same. Treatment of either group of animals by intramuscular injection of estradiol (1 mg/kg body wt/day) for 10 days induced ADH activity in kidney two- to threefold, whether the activity was expressed as U/g tissue, U/g protein, or U/mg DNA. Estradiol induced kidney ADH mRNA in both ovariectomized and sham-operated rats approximately twofold. Thus, induction of ADH mRNA accounts for the increase in ADH activity. In situ hybridization indicated that the ADH mRNA was present in the inner cortex and medulla of the kidney. Methylation patterns of the ADH gene were examined. The gene resides in a methylated region of chromatin without any of the typical features of a HpaII tiny fragment (HTF) island. Two MspI sites flanking the transcription start site are undermethylated in liver compared with kidney and spleen. This suggests that methylation of this gene may play a role in the tissue-specific expression of ADH.

Androgen regulation of the mRNA encoding a major protein of the mouse vas deferens

A cDNA encoding the major mouse vas deferens protein (MVDP) has been cloned and characterized. Using in situ hybridization we have identified the epithelial cells of the vas deferens as the site of synthesis of MVDP mRNA. Northern blot analysis suggests that a high level of an mRNA corresponding to the MVDP gene is present in the mouse vas deferens whereas the amount of MVDP mRNA in vas deferens of other species studied, or in other mouse tissues, even if present, is undetectable. Steady-state levels of MVDP mRNA are decreased by approximately 42% 3 days after castration but a significant hybridization signal is still observed even 50 days after castration. Testosterone treatment for 2 weeks is necessary to completely reverse the effect of castration. In vitro transcription assays on isolated nuclei showed that the hormonal induction of the MVDP gene is achieved mainly at transcriptional level.

The gene for the beta-subunit of retinal transducin (Gnb-1) maps to distal mouse chromosome 4, and related sequences map to mouse chromosomes 5 and 8

The heterotrimeric G protein transducin releases cGMP-phosphodiesterase from inhibition in retinal rod photoreceptor cells when stimulated by light-activated rhodopsin. As a result the level of cGMP goes down, the rod plasma membrane hyperpolarizes, and the release of neurotransmitter is modified. We have used a bovine cDNA for the beta-subunit of transducin (G beta 1) to map its gene Gnb-1 to distal mouse chromosome 4. This cDNA also identified two other homologous sequences in the mouse genome. One of the sequences was on chromosome 5 which we identified as the locus of Gnb-2, a second G protein beta-subunit gene. The other sequence was on chromosome 8 and is either a pseudogene or an as yet undiscovered third G beta-subunit gene, here termed Gnb-3.

Progressive induction of mRNA synthesis for androgen-responsive genes in mouse kidney

A number of mRNAs present in kidney are selectively induced by the administration of androgen to mice. Using a pulse-labelling method to measure in vivo rates of mRNA synthesis, seven androgen-responsive mRNAs were tested. The time courses of induction following testosterone treatment indicated that androgen-responsive mRNA synthesis increases progressively. Depending on the mRNA examined, it took 2-10 days after the start of hormone administration for synthesis rates to reach a maximum. Even the fastest of these inductions is slow compared to response times in other steroid-responsive systems, and is very slow compared to the time required for androgen-receptor complex to accumulate in the nucleus. We conclude that gene activation in response to androgen is a prolonged and incremental process rather than a single event. Two alternative models are proposed: (1) these genes are actually responding to intermediate transcription factors that accumulate progressively in response to androgen; (2) the androgen-responsive genes contain multiple binding sites that have a cumulative effect on transcription as the number of receptor complexes bound increases.

Arylsulfatase and beta-glucuronidase expression in green sunfish, bluegill, and their reciprocal interspecific hybrids

Fish arylsulfatases (arylsulfate sulfohydrolase; EC 3.1.6.1) were resolved into cationic arylsulfatase A-like (ARSA) and anionic arylsulfatase B-like (ARSB) fractions by DEAE-Sephacel chromatography. Green sunfish (GSF) hepatic ARSA was more acidic and more thermostable than bluegill (BG) ARSA. GSF x BG interspecific hybrids preferentially expressed GSF ARSA, while BG x GSF hybrids appeared to produce a dimeric enzyme consisting of both GSF and BG ARSA polypeptides. GSF hepatic beta-glucuronidase (GUS) also proved to be more thermostable than BG GUS. Thermostabilities of GUS produced by reciprocal interspecific hybrids were very similar to that of GSF GUS. Either GSF GUS is preferentially expressed in both interspecific hybrids or both the GSF and BG GUS polypeptides are synthesized in comparable amounts, and the GSF GUS polypeptide sufficiently stabilizes the heterotetramers produced by the hybrids to produce denaturation profiles closely approximating that of the GSF enzyme.

The N haplotype of the murine beta-glucuronidase gene is altered in both its systemic regulation and its response to androgen induction

A new haplotype of the beta-glucuronidase gene complex, [Gus]N, has been characterized following its transfer from the PAC/Cr strain to the standard strain C57BL/6J. The N haplotype contains a novel structural gene allele which encodes an allozyme differing from all previously characterized allozymes in both size and charge. Altered systemic regulation is exhibited by the [Gus]N haplotype. Multiple tissues contain levels of GUS protein that are 60 +/- 15% those found in the standard B haplotype. The regulatory mechanism for reduction is complex, involving tissue-specific changes in both enzyme synthesis and enzyme turnover. The changes in GUS protein synthesis do not result from changes in GUS mRNA levels. Instead, the amount of mature enzyme formed per mRNA molecule, or translational yield, is altered. These regulatory changes parallel those seen in other systemic regulatory variants of GUS which are also altered in translational yield. A commonality of mechanism among systemic regulatory variants of this gene is suggested. The N haplotype is also exceptional in the nature of its response to androgenic induction in kidney proximal tubule epithelial cells. The time course for GUS induction consists of a lag period followed by a progressive increase in mRNA, rate of enzyme synthesis, and enzyme activity. For the [Gus]N haplotype the lag is of an exceptionally short duration and the plateau is of a greater magnitude than for any haplotype previously described.

mRNA synthesis rates in vivo for androgen-inducible sequences in mouse kidney

A method was developed for measuring in vivo rates of mRNA synthesis in mice by pulse-labeling with the RNA precursor [3H]orotate and then using hybridization to recover specific mRNAs. The efficiency of recovery is determined with synthetic RNAs as internal hybridization standards. The method is particularly applicable to the kidney since this organ shows a strong preferential uptake of the label. Rates of synthesis, expressed as a fraction of total RNA synthesis, were measured for the androgen-inducible mRNAs coding for beta-glucuronidase (GUS), ornithine decarboxylase (ODC), the protein coded by the RP-2 gene, and the so-called kidney androgen-regulated protein (KAP). Control mRNAs coded for beta-actin, phosphoenolpyruvate carboxykinase, and major urinary protein. Testosterone markedly increased the synthesis of the androgen-inducible mRNAs, but not the control mRNAs. Induction was not seen in mutant mice lacking functional androgen receptor protein. For GUS, ODC, and RP-2 mRNAs, the fold induction of synthesis was less than the fold induction of concentration, suggesting that mRNA stabilization also plays a part in the response to androgen. For GUS, ODC, and RP-2 mRNAs, but not KAP mRNA, induction of synthesis was rapidly reversed after testosterone removal. KAP mRNA was also exceptional in that its concentration was disproportionately high compared with its rate of synthesis, implying that it is a particularly stable mRNA.

mRNA synthesis rates in vivo for androgen-inducible sequences in mouse kidney

A method was developed for measuring in vivo rates of mRNA synthesis in mice by pulse-labeling with the RNA precursor [3H]orotate and then using hybridization to recover specific mRNAs. The efficiency of recovery is determined with synthetic RNAs as internal hybridization standards. The method is particularly applicable to the kidney since this organ shows a strong preferential uptake of the label. Rates of synthesis, expressed as a fraction of total RNA synthesis, were measured for the androgen-inducible mRNAs coding for beta-glucuronidase (GUS), ornithine decarboxylase (ODC), the protein coded by the RP-2 gene, and the so-called kidney androgen-regulated protein (KAP). Control mRNAs coded for beta-actin, phosphoenolpyruvate carboxykinase, and major urinary protein. Testosterone markedly increased the synthesis of the androgen-inducible mRNAs, but not the control mRNAs. Induction was not seen in mutant mice lacking functional androgen receptor protein. For GUS, ODC, and RP-2 mRNAs, the fold induction of synthesis was less than the fold induction of concentration, suggesting that mRNA stabilization also plays a part in the response to androgen. For GUS, ODC, and RP-2 mRNAs, but not KAP mRNA, induction of synthesis was rapidly reversed after testosterone removal. KAP mRNA was also exceptional in that its concentration was disproportionately high compared with its rate of synthesis, implying that it is a particularly stable mRNA.

The complete nucleotide sequence of murine beta-glucuronidase mRNA and its deduced polypeptide

The complete nucleotide sequence of murine beta-glucuronidase (GUS) mRNA has been compiled from three overlapping cloned cDNAs and a single GUS-specific genomic clone. The sequence is composed of 2455 nucleotides, exclusive of the poly(A) tail. The 5' and 3' untranslated regions contain 12 and 499 bases, respectively, with the open reading frame encoding a polypeptide of 648 amino acids (74.2 kDa), including a 22 amino acid signal sequence. The nucleotide and deduced amino acid sequences of murine GUS are compared to those published for rat and human GUS and the results are presented. Murine GUS also shares amino acid sequence identity with Escherichia coli GUS and beta-galactosidase. The complete sequences of murine GUS mRNA and its deduced polypeptide provide a basis from which to study the mechanisms responsible for the well-characterized variation in GUS expression among inbred mouse strains.

Chemical kinetics of induced gene expression: activation of transcription by noncooperative binding of multiple regulatory molecules

A chemical kinetics model is described for the regulation of gene expression by the progressive binding of regulatory molecules to specific binding sites on DNA. Chemical rate equations are formulated and solved for the accumulation of regulatory molecules on DNA, the change in the level of induced mRNA, and the change in the level of the encoded protein in the activated tissue. Some special cases are examined, including that of an activation threshold created by a requirement for the binding of a minimum number of regulatory molecules prior to gene activation. Experimental data for several hormone-activated genetic systems are analyzed in the frame of the proposed model, and kinetic parameters are predicted. The model accounts for a number of experimental characteristics of hormone-inducible genetic systems, including the existence of a lag in the time course of mRNA accumulation, the sigmoidal curve of induced mRNA kinetics, the effect of hormone on mRNA stabilization, and the induction parameters observed when hormone analogues are used. The model also provides an explanation for the phenotypes of genetic variants with altered inducibility as changes in the molecular kinetic parameters of gene activity.

Rat liver beta-glucuronidase. cDNA cloning, sequence comparisons and expression of a chimeric protein in COS cells

A cDNA for rat liver beta-glucuronidase was isolated, its sequence determined and its expression after transfection into COS cells studied. The deduced amino acid sequence of the rat liver clone showed 77% homology with that from the cDNA for human placental beta-glucuronidase and 47% homology with that deduced from the cDNA for Escherichia coli beta-glucuronidase. Several differences were found between the cDNA from rat liver and that previously reported from rat preputial gland. Only one change leads to an amino acid difference in the mature enzyme. A chimeric clone was constructed by using a fragment encoding the first 18 amino acid residues of the signal sequence from the human placental cDNA clone and a fragment from the rat clone encoding four amino acid residues of the signal sequence, all 626 amino acid residues of the mature rat enzyme, and all of the 3' untranslated region. After transfection into COS cells the chimeric clone expressed beta-glucuronidase activity that was specifically immunoprecipitated by antibody to rat beta-glucuronidase. The Mr value of 76,000 of the expressed gene product was characteristic of the glycosylated rat enzyme. It was proteolytically processed in COS cells to Mr 75,000 6 h after metabolic labelling. At least 50% of the expressed enzyme was secreted at 60 h post-transfection, but the secreted enzyme did not undergo proteolytic processing. These results provide evidence that the partial cDNA isolated from a rat liver library contains the complete coding sequence for the mature rat liver enzyme and that the chimeric signal sequence allows normal biosynthesis and processing of the transfected rat liver enzyme in COS cells.

Antisense RNA inhibits endogenous gene expression in mouse preimplantation embryos: lack of double-stranded RNA "melting" activity

beta-Glucuronidase activity increases 60-fold from the 4-cell to the blastocyst stage during in vitro development of mouse preimplantation embryos, secondary to a 13-fold increase in beta-glucuronidase mRNA. Injections of antisense RNA from a beta-glucuronidase cDNA clone lacking the 5'-untranslated region and the coding sequences for approximately equal to 150 N-terminal amino acids were effective in partially blocking the appearance of beta-glucuronidase activity. Injection of the same RNA, capped with guanosine(5')triphospho(5')guanosine (GpppG), into each blastomere at the 4-cell stage yielded 75% inhibition of enzyme activity at the blastocyst stage. Injections of the sense strand or of an unrelated RNA did not alter the normal increase in activity of the enzyme. These results are in accord with our inability to detect RNA-duplex "melting" activity in 1-cell mouse embryos. We suggest that it may be possible to analyze genetics of mammalian development by antisense techniques.

Genome organization and polymorphism of the murine beta-glucuronidase region

Thirty-eight kilobases of mouse genomic DNA which surround and include the coding sequences for beta-glucuronidase has been mapped. Intron-exon arrangements were determined by hybridization of genomic sequences with cDNA clones, and minimum estimates of gene length (11-17 kb) and intron number were obtained. Only a single gene was observed when genomic DNA was probed with subclones containing beta-glucuronidase coding sequence; there was no evidence of duplicated or pseudogenes. However, sequences distal to the 3' end of the gene are present elsewhere in the genome in a limited number of copies. Eight haplotypes of the beta-glucuronidase region with differing regulatory genotypes were compared for restriction fragment polymorphisms. Surprisingly little was found, considering the diverse origin of the haplotypes. Two of the polymorphisms that were found may be correlated with regulatory phenotypes. A BamHI site is missing from the CS and CL haplotypes that share regulatory properties, and a 0.2-kb insertion is consistently present in haplotypes showing increased response to induction by androgens in kidney.

Changes in translational yield regulate tissue-specific expression of beta-glucuronidase

The number of beta-glucuronidase (GUS; beta-D-glucuronoside glucuronosohydrolase, EC 3.2.1.31) molecules per cell varies as much as 12-fold among mouse tissues. To identify the regulatory mechanisms responsible, estimates of the rates of GUS protein synthesis (ks) and degradation (kd) were obtained for six tissues in the B6.PAC-Gusn mouse strain, which carries the N haplotype of the GUS gene. Differences in enzyme levels among tissues were predominantly due to differences in rates of enzyme synthesis; only brain differed significantly in the rate of protein degradation. Typically, tissues contain about 2 molecules of GUS mRNA per cell. Differences in GUS mRNA levels were found among tissues, but these were not sufficient to account for observed differences in ks. This suggests that tissues differ in translational yield, which is defined as the product of the efficiency with which the GUS message is translated and the fraction of newly made polypeptides that are successfully matured into GUS tetramers. Experimental estimates of translational yield confirmed that this is indeed a source of tissue differences in GUS gene regulation. This finding also proved to be true of the B haplotype of the GUS gene. The differential regulation of special-function genes is, in general, effected transcriptionally. In contrast, the differential regulation of several "housekeeping" genes has been reported to arise from changes in mRNA maturation and/or stability. It is now apparent that translational yield, which is an aspect of protein synthesis, can also serve as a differential regulatory mechanism.

Androgen regulated expression of a spermine binding protein gene in mouse ventral prostate

A full length cDNA (MP25) encoding the major mouse prostatic secretory glycoprotein (p25), whose expression is androgen dependent, has been cloned and characterised. Steady-state levels of mRNA are decreased approximately 100-fold after 3 days castration but are restored progressively over 4 days with testosterone treatment. The secreted glycoprotein appears to be a spermine binding protein since the nucleotide and predicted amino acid sequence of MP25 shares extensive homology with a spermine binding protein (SBP) found in rat ventral prostate. Genomic clones indicate that there is a single gene for SBP which consists of 4 exons, the first of which is only 11bp in length. The second exon encodes the signal peptide, the third contains a portion of the spermine binding protein unique to the mouse and the largest exon encodes the bulk of the secreted protein.

DNA sequence variation within the beta-glucuronidase gene complex among inbred strains of mice

Tightly linked to the gene that encodes murine beta-glucuronidase (GUS) are three GUS-specific regulatory elements. Together, these elements define the GUS gene complex. Specific alleles of each regulatory element are associated with a specific GUS structural allele. These associations define the three common forms (haplotypes) of the GUS gene complex, designated A, B, and H. As an initial step in defining the DNA determinants of each regulatory element and to develop DNA markers for the common haplotypes, we have identified several DNA variants by blot hybridization analysis of restricted genomic DNA using GUS-specific cDNA probes. Of 30 tested restriction endonucleases, 24 reveal DNA polymorphisms that distinguish B- and H-haplotype DNA from that of the A haplotype. Of these 24, 18 uncover a restriction fragment length polymorphism in which the polymorphic fragment of A-haplotype DNA is 200-300 bp larger than the corresponding fragment of B- or H-haplotype DNA. DNA sequence analysis of this polymorphic region reveals the presence of a short, interspersed repetitive element of the B2 family within A-haplotype DNA which is absent in DNAs of B- or H-haplotype mice. None of the DNA variations revealed by these analyses can be associated at this time with variation in the regulatory or structural properties of GUS among the common haplotypes. Nevertheless, they do provide useful haplotype-specific markers within the GUS gene complex which are of critical importance for DNA transfer experiments in transgenic mice and in cultured cells.

Genetic variations in kinetic constants that describe beta-glucuronidase mRNA induction in androgen-treated mice

The kinetics of beta-glucuronidase mRNA induction by androgen in mouse kidney were determined for A, B, and CS haplotypes of the beta-glucuronidase gene. After a lag period, the kinetics of mRNA (R) induction are approximated by the turnover equation dR/dt = k1 - k2R. The A haplotype differs from the B primarily in the duration of the lag period and in k1, the rate constant determining the initial slope of the induction curve. The CS haplotype differs from B primarily in k2, the first-order rate constant that determines the half-time for induction. None of the haplotypes differs significantly in the half-life of beta-glucuronidase mRNA as measured by deinduction. Thus, there was no correlation between the half-time or extent of induction and the half-life of the RNA. Comparing half-times for induction with the half-life of the mRNA suggests that message stabilization can at most account for only part of the induction. We conclude that transcriptional activation of the beta-glucuronidase gene must be an important component of induction. Estimating absolute numbers of mRNA molecules and absolute rates of gene transcription, it appears that before induction there is approximately one molecule of beta-glucuronidase mRNA per cell and that each gene copy is transcribed once every 35 to 40 h. Depending on the haplotype examined, after induction, mRNA goes up to 80 to 400 molecules per induced cell. In the A haplotype, which has the highest induction, this corresponds to one transcript from each gene every 6 min if there is no induced stabilization of beta-glucuronidase mRNA, and one every 30 min if there is. Thus, it seems unlikely that more than one transcript is ever being synthesized at the same time from the beta-glucuronidase gene.

Effects of differentiation-inducing agents on synthesis, maturation and secretion of cathepsin D in U937 and HL-60 cells

Treatment of human monocyte U937 and promyelocyte HL-60 cultures with agents known to induce differentiation (12-O-tetra-decanoylphorbol 13-acetate, calcitriol and dimethylsulfoxide) accelerates the maturation of cathepsin D and enhances the incorporation of [35S]methionine into cathepsin D. The most pronounced effects are obtained with calcitriol, which at a concentration of 10(-7) M increases the incorporation of [35S]methionine into cathepsin D from 0.08% to 0.4% of the detergent-soluble radioactivity. In addition, this treatment enhances the secretion of cathepsin D from about 8% to greater than or equal to 16% of the newly synthesized enzyme. In the presence of 10mM NH4Cl approximately half of the produced cathepsin D is secreted in both control and calcitriol-treated cells. It appears that in U937 cells two mechanisms are involved in sorting of cathepsin D. One of these is sensitive to NH4Cl and its efficiency is selectively decreased in cells pretreated with calcitriol.

Genetic variations in kinetic constants that describe beta-glucuronidase mRNA induction in androgen-treated mice

The kinetics of beta-glucuronidase mRNA induction by androgen in mouse kidney were determined for A, B, and CS haplotypes of the beta-glucuronidase gene. After a lag period, the kinetics of mRNA (R) induction are approximated by the turnover equation dR/dt = k1 - k2R. The A haplotype differs from the B primarily in the duration of the lag period and in k1, the rate constant determining the initial slope of the induction curve. The CS haplotype differs from B primarily in k2, the first-order rate constant that determines the half-time for induction. None of the haplotypes differs significantly in the half-life of beta-glucuronidase mRNA as measured by deinduction. Thus, there was no correlation between the half-time or extent of induction and the half-life of the RNA. Comparing half-times for induction with the half-life of the mRNA suggests that message stabilization can at most account for only part of the induction. We conclude that transcriptional activation of the beta-glucuronidase gene must be an important component of induction. Estimating absolute numbers of mRNA molecules and absolute rates of gene transcription, it appears that before induction there is approximately one molecule of beta-glucuronidase mRNA per cell and that each gene copy is transcribed once every 35 to 40 h. Depending on the haplotype examined, after induction, mRNA goes up to 80 to 400 molecules per induced cell. In the A haplotype, which has the highest induction, this corresponds to one transcript from each gene every 6 min if there is no induced stabilization of beta-glucuronidase mRNA, and one every 30 min if there is. Thus, it seems unlikely that more than one transcript is ever being synthesized at the same time from the beta-glucuronidase gene.

Cloning, sequencing, and expression of cDNA for human beta-glucuronidase

We report here the cDNA sequence for human placental beta-glucuronidase (beta-D-glucuronoside glucuronosohydrolase, EC 3.2.1.31) and demonstrate expression of the human enzyme in transfected COS cells. We also sequenced a partial cDNA clone from human fibroblasts that contained a 153-base-pair deletion within the coding sequence and found a second type of cDNA clone from placenta that contained the same deletion. Nuclease S1 mapping studies demonstrated two types of mRNAs in human placenta that corresponded to the two types of cDNA clones isolated. The NH2-terminal amino acid sequence determined for human spleen beta-glucuronidase agreed with that inferred from the DNA sequence of the two placental clones, beginning at amino acid 23, suggesting a cleaved signal sequence of 22 amino acids. When transfected into COS cells, plasmids containing either placental clone expressed an immunoprecipitable protein that contained N-linked oligosaccharides as evidenced by sensitivity to endoglycosidase F. However, only transfection with the clone containing the 153-base-pair segment led to expression of human beta-glucuronidase activity. These studies provide the sequence for the full-length cDNA for human beta-glucuronidase, demonstrate the existence of two populations of mRNA for beta-glucuronidase in human placenta, only one of which specifies a catalytically active enzyme, and illustrate the importance of expression studies in verifying that a cDNA is functionally full-length.

Unique patterns of androgen regulation of the expression of two genes in murine kidney

The kidneys of androgen stimulated mice exhibit a hypertrophic response but no hyperplasia or concomitant DNA replication. Androgens increase the expression of several genes in mouse kidney. The response of the beta-glucuronidase gene to testosterone in this tissue is characterized by a 1-2 day lag and relatively slow induction kinetics. The gene coding for kidney androgen-regulated protein (KAP) exhibits quite a different response to the hormone when compared on the basis of initial response to a given dose, dose required to produce maximal response, and apparent sensitivity to low levels of androgen-receptor complexes in renal nuclei. The analysis of the accumulation of the mRNAs produced by these two genes suggests that gene-specific differential sensitivity to androgen receptor complexes governs the development of the cellular male phenotype in this tissue.

Nucleotide sequence of rat preputial gland beta-glucuronidase cDNA and in vitro insertion of its encoded polypeptide into microsomal membranes

We have selected the rat preputial gland beta-glucuronidase as a model protein to study the sorting of newly synthesized lysosomal hydrolases to the lysosome. The complete coding sequence of beta-glucuronidase messenger RNA was determined from the sequences of a group of overlapping cDNA clones isolated from preputial gland cDNA libraries. The beta-glucuronidase mRNA primary translation product contains 648 amino acids, including an amino-terminal signal sequence of 22 residues. The polypeptide has four potential sites for the addition of asparagine-linked core oligosaccharides. A 376-residue segment of beta-glucuronidase shows extensive homology (23% sequence identity) to a portion of Escherichia coli beta-galactosidase. This homology most likely reflects an evolutionary relationship between the bacterial and eukaryotic enzymes and the conservation of structural features necessary for the glycosidase activity of both proteins. Translation of mRNA synthesized in vitro by transcription of a cDNA containing the entire beta-glucuronidase coding region yielded a polypeptide that was immunoprecipitated with anti-beta-glucuronidase antiserum and had the same electrophoretic mobility as the primary translation product of natural beta-glucuronidase mRNA. In the presence of microsomal membranes, the in vitro-synthesized beta-glucuronidase underwent cotranslational incorporation into the microsomes, as indicated by removal of the signal sequence and the addition of several oligosaccharide chains. The beta-glucuronidase cDNA will provide a useful tool to study the mechanism of mannose phosphorylation and other aspects of the sorting of lysosomal enzymes to lysosomes.

Androgen induction of alcohol dehydrogenase in mouse kidney. Studies with a cDNA probe confirmed by nucleotide sequence analysis

A cDNA clone for the beta-chain of human alcohol dehydrogenase (ADH) was used to isolate several cross-hybridizing clones from a mouse liver cDNA library. Clones pADHm9 and a portion of pADHm12 were sequenced. pADHm9 coded for a sequence of 151 C-terminal amino acids and some untranslated sequences from the 3' end of its corresponding mRNA. This clone was identified as an Adh-1 cDNA clone. Consistent with the known expression of Adh-1, this gene was expressed constitutively in liver, whereas the Adh-3 gene product was found only in stomach, lung and reproductive tissues. Furthermore, the translated region of the cDNA shared 91% amino acid sequence homology with rat liver ADH. [32P]pADHm9 was used as a hybridization probe to study the mechanism of androgen induction of kidney ADH activity. Induction of A/J female mice by androgen resulted in a dramatic increase in the steady-state level of Adh-1 mRNA content which correlated with the level of enzyme induction. The size of the mRNA obtained from control or induced kidney and liver tissues was indistinguishable by Northern analysis. [32P]pADHm9 was also used to probe restriction fragments of genomic DNA obtained from several inbred mouse strains. The hybridization patterns, considered with the genetic evidence, suggested that pADHm9 recognized sequences which may be present as only a single copy in the genome. No restriction fragment length polymorphisms were observed among the several inbred mouse strains examined.