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K Paigen

Publications and source records attributed to K Paigen.

At least 37 records · Page 2Linked to original sources
PubMed1985

Weak androgen reduces the rate constant of beta-glucuronidase induction.

Administration of androgen to mice induces kidney beta-glucuronidase. Measuring beta-glucuronidase activity, rate of beta-glucuronidase synthesis, beta-glucuronidase mRNA activity and beta-glucuronidase mRNA concentration, the time course of induction was compared using a strong androgen, dihydrotestosterone (DHT), and a weakly androgenic progestin, medroxyprogesterone acetate (MPA). Using MPA resulted in a longer lag, a 3-4-fold slower rate of induction as defined by the forward rate constant, ka, a lower final extent of induction, and a slightly lower turnover constant, kb. Differences in kinetics of induction were consistent for all 4 measured parameters, and mimicked previously described genetic differences in these rate constants. The coordinate induction of beta-glucuronidase protein and beta-glucuronidase mRNA indicates that the response to androgen is regulated at a pre-translational level. That substitution of MPA for DHT decreases ka, rather than increasing kb, suggests that induction of beta-glucuronidase follows an increased rate of mRNA synthesis rather than a decreased rate of mRNA turnover. Finally, the results are consistent with a model in which the kinetic constants for beta-glucuronidase induction are dependent on the concentration of receptor molecules in the active conformational state.

Animals↗
PubMed1984

Kinetics of beta-glucuronidase induction by androgen. Genetic variation in the first order rate constant.

Measurements of enzyme activity, rates of protein synthesis, and mRNA activity suggest that the induction of beta-glucuronidase in mouse kidney in response to androgen is regulated at a pretranslational level. Following an initial lag period, the rate and extent of induction follow the rules of simple turnover kinetics and can be described in terms of a zero order rate constant for acquisition of mRNA activity (ka) and a first order rate constant for loss of activity (kb). Genetic variation in kb, described here for the first time, alters the half-time and extent of induction. Variation in kb is independent of previously described variation in ka and, unlike changes in ka, is not associated with change in the lag time. The DNA sequences determining kb, like those determining ka, are genetically linked to the structural gene for beta-glucuronidase. Following the removal of androgen, beta-glucuronidase activity, rate of synthesis, and mRNA activity all decline rapidly with half-lives of 1-2 days. Even in the most rapidly inducing strains, this is significantly faster than the half-time for induction determined by kb. Furthermore, genetic variation in kb does not affect the rate of de-induction. These facts suggest that kb may not describe the turnover of beta-glucuronidase mRNA, but rather the turnover of another step in the induction process.

Animals↗
PubMed1984

A genetic component in human lysosomal enzyme excretion.

Acid hydrolases are present in normal human urine in appreciable amounts. Their source appears to be lysosomes released by kidney proximal tubule epithelial cells. For a given lysosomal enzyme the total amount excreted is the product of two parameters, a general one describing the rate of lysosome secretion and a specific one describing the relative concentration of that enzyme in lysosomes. There is considerable population variation in both parameters. Studies of beta-glucuronidase, beta-galactosidase, beta-hexosaminidase, and alpha-galactosidase in monozygotic and dizygotic twins show that an appreciable part of this variation is genetic in origin. This appears to be true for both total enzyme excretion and lysosome composition. Although it was not possible to test directly whether this is also true for the rate of lysosome secretion, the fact that the two former parameters are both heritable strongly suggests that the rate of lysosome excretion is also a heritable trait. Taken together with previous data, the results suggest polygenic control of these biochemical traits. It is particularly significant that beta-glucuronidase excretion in normal individuals is a heritable trait since the excretion of this enzyme has frequently been used as a measure of normal and pathological physiological changes.

Adolescent↗
PubMed1984

Role of urinary beta-glucuronidase in human bladder cancer.

It has been suggested that high levels of urinary beta-glucuronidase may increase an individual's risk of bladder cancer by releasing free carcinogens from their inactive glucuronide conjugates in the bladder. The hypothesis derives in part from the high levels of urinary beta-glucuronidase observed in bladder cancer patients. Because most of the individual variation in levels of urinary beta-glucuronidase and other lysosomal enzymes in the normal population is genetically determined, we would expect that, if high glucuronidase levels were a predisposing factor in the disease, bladder cancer patients would transmit this trait to their progeny. We have tested this hypothesis and find that levels of urinary beta-glucuronidase and three other lysosomal enzymes, alpha-galactosidase, beta-galactosidase, and beta-hexosaminidase, are not significantly elevated in 34 progeny of bladder cancer patients compared to 34 matched controls. Additionally, 15 bladder cancer patients judged to be disease free for a median time of 5 years did not have elevated levels of urinary beta-glucuronidase when compared to a normal population of 125 individuals. Thus, the high levels of glucuronidase observed in bladder cancer patients are most likely a consequence of disease rather than a cause.

Adult↗
PubMed1983

Trans-acting temporal locus within the beta-glucuronidase gene complex.

Mice carrying the [Gus]H haplotype of the beta-glucuronidase gene complex have considerably decreased enzyme levels and a decreased rate of enzyme synthesis. This is now shown to result from the action of two regulatory loci within the gene complex. One is a systemic regulator, Gus-u, that acts cis to cause a uniform reduction in enzyme levels in all tissues. The other is a temporal locus, Gus-t, that acts trans to cause abrupt switches in the rate of enzyme synthesis in only certain tissues and at characteristic stages of development. The distinction between these two loci was made possible by the introduction of a method for quantitating the relative numbers of A and H allozyme subunits in beta-glucuronidase tetramers. The procedure involves purification of the enzyme, cleavage at methionyl residues with CNBr, isoelectric focusing to separate the peptides, and quantitation of the peptide containing the A/H amino acid substitution. The presence of a trans-acting regulatory locus within a gene complex raises evolutionary and functional questions about why it is located there and how it acts.

Aging↗
PubMed1982

Progressive induction of beta-glucuronidase in individual kidney epithelial cells.

The magnitude and kinetics of beta-glucuronidase induction in mouse kidney are determined by a cis-acting regulatory gene, Gus-r, that is closely linked to the enzyme structural gene. The accumulation of beta-glucuronidase mRNA during induction is much slower than the turnover time of the mRNA, suggesting progressive acquisition of mRNA synthesizing capacity during induction. Counts of the numbers of induced cells present at various times of induction in strains carrying three different alleles of Gus-r show that all potentially responsive cells respond immediately. The level of induction is progressive in individual cells and does not involve continued recruitment of new cells into the induced population. It appears that during induction each chromosome becomes progressively more active in directing the synthesis of beta-glucuronidase.

Animals↗
PubMed1982

Expression of beta-glucuronidase haplotypes in prototype and congenic mouse strains.

A gene complex consists of a structural gene with its associated regulatory information; together they behave as the functional and evolutionary unit of mammalian chromosomes. The use of congenic lines, in which alternate forms, or haplotypes, of a gene complex are transferred into a common genetic background by repeated backcrossing, provides a means of comparing the regulatory properties of different haplotypes of a gene complex without the complications introduced by extraneous genetic differences. We have now carried out such a study of the A, B, and H haplotypes of the beta-glucuronidase gene complex, [Gus], in mice. These haplotypes were derived from strains A/J, C57BL/6J, and C3H/HeJ and were compared against the C57BL/6J genetic background. Enzyme structure was compared in terms of charge (isoelectric point), stability (rate of thermal denaturation), substrate affinity (for 4 MU glucuronide), and antigenicity (reactivity with a standard antibody). Compared to the B form, the enzyme coded by the A haplotype has a lower isoelectric point, and that coded by the H haplotype is less stable. The decreased stability is the result of a lower activation energy for the thermal denaturation reaction. These differences were maintained in the congenic strains. All three enzyme forms showed identical substrate affinities. Antigenicity per enzyme unit was also identical for all three, indicating that none lacks an antigenic site possessed by the others and that they all possess the same catalytic activity per molecule. The expression of alleles of the Gus-t temporal locus within the gene complex was not affected by transfer into the C57BL/6 genetic background. The same developmental switches in enzyme activity were seen in each case. Transfer into the C57Bl/6 background also did not affect expression of the Gus-r regulator determining androgen inducibility of beta-glucuronidase synthesis in kidney epithelial cells. However, enzyme accumulation in induced cells was altered when the haplotypes were transferred into the C57BL/6 genetic background. Since the rate of synthesis was not affected, it suggests that the genetic differences between strains that are not linked to the [Gus] complex affect the rate of enzyme loss by degradation or secretion. Beta-Glucuronidase in liver is present in both lysosomes and endoplasmic reticulum (microsomes). The relative amount of enzyme at each site depended on both the indentity of the structural allele and the function of unlinked genetic modifiers. Within the C57BL/6 background the percentage of total enzyme present in the microsome fraction was the order A greater than B greater than H. For the H form of the enzyme the percentage was appreciably greater in the C3H genetic background compared to C57BL/6. As expected, then, the [Gus] complex contains all of the genetic determinants of enzyme structure detected by thermal stability and isoelectric point measurements...

Animals↗
PubMed1982

A new method of screening for inherited disorders of galactose metabolism.

A method has been developed for detecting elevated levels of galactose and galactose-1-phosphate in routine blood samples of newborns and has been successfully applied as a screening procedure for galactosemia in several laboratories. The procedure utilizes a strain of Escherichia coli that becomes resistant to bacteriophage C21 in the presence of galactose. The presence of galactose or galactose-1-phosphate is detected as a zone of bacterial growth around blood spots placed on a dish in which the bacteria are otherwise killed by phage. The diameter of the growth zone is proportional to the concentration of total blood galactose. The procedure has the potential of detecting all metabolic abnormalities that can lead to the accumulation of galactose or galactose-1-phosphate. Over a million newborn infants have now been tested by this procedure in three countries. In the New England Regional Screening Program, 12 galactosemic children were detected in 825,403 live births. One additional case, a sibling of a previously diagnosed galactosemic, was not allowed any milk feeding and was detected by an enzymatic test of cord blood. The combined frequency was 1:63,000. No problems of interference by antibiotics were apparent. Use of the test in Switzerland and in Japan also allowed the discovery of infants with UDP galactose 4-epimerase deficiency. Our experience suggests that the test provides an efficient and reliable means of detecting congenital defects of galactose metabolism with a very low frequency of errors. It can also be used to monitor blood galactose levels in the management of galactosemic children.

Bacteriophages↗
PubMed1981

Genetic determination of kinetic parameters in beta-glucuronidase induction by androgen.

A regulatory locus, Gus-r, determines the rate and extent of androgen inducibility of beta-glucuronidase in mouse kidney epithelial cells. The kinetics of induction are strikingly similar when enzyme concentration, rates of enzyme synthesis, and beta-glucuronidase mRNA are measured. After an initial lag period the accumulation of mRNA activity obeys simple turnover kinetics defined by ka, a zero order rate constant for acquisition of mRNA activity, and kb, a first order rate constant for loss of activity. The induced state is approached with a half-life of 8-9 days in the presence of testosterone and decays rapidly in the absence of testosterone. The half-life of both beta-glucuronidase and its mRNA appear to be much shorter, approximately 1-2 days, in both the presence and absence of testosterone. We conclude that the material accumulating in response to androgen is probably a transcriptionally activated state of beta-glucuronidase chromatin. Comparison of the a and b alleles of Gus-r, and a newly described h allele, shows that Gus-r determines ka and the duration of the lag period, but not kb, which was genetically invariant. The changes in ka and the duration of the lag are inversely related, suggesting that they reflect a common step during induction. These results are most simply accounted for by assuming that beta-glucuronidase regions in chromatin react with many molecules of androgen receptor protein-testosterone complex and that the rate of transcription is a function of the number of molecules bound. The lag period, then, reflects a requirement that a minimum number of sites must be occupied before transcription begins to increase. We suggest that the Gus-r locus determines the accessibility or affinity of androgen receptor complexes to chromatin. Because of this Gus-r determine both ka and the duration of the lag and the two parameters are inversely related to each other.

Amanitins↗
PubMed1980

Quantitation of cis versus trans regulation of mouse beta-glucuronidase. Action of alleles of the Gus-r locus determining androgen inducibility.

Genetic studies have shown that the induction of beta-glucuronidase in mouse kidney in response to androgens is under the control of the Gus-r gene, closely linked to the beta-glucuronidase structural gene, Gus-s, on mouse Chromosome 5. Despite the fact that a single structural gene codes for beta-glucuronidase, enzyme molecules show considerable charge heterogeneity, presumably as a result of post-translational events. Because the enzyme is a tetramer, this heterogeneity has complicated examination of the cis versus trans action of the Gus-r gene. In order to resolve the problem, we have developed a quantitative method for determining the amount of beta-glucuronidase derived from each structural allele in mice heterozygous for beta-glucuronidase electrophoretic mobility. The method involves separation and quantitation of genetically variant cyanogen bromide peptides from the enzyme. Using this technique, we show that Gus-r acts cis, suggesting that it directly affects the template activity of the glucuronidase structural gene.

Alleles↗
PubMed1979

Cis-active control of mouse beta-galactosidase biosynthesis by a systemic regulatory locus.

Several higher organisms have been reported in which enzyme levels are determined genetically by sites located in close proximity to the corresponding structural genes. In several cases, these sites have been shown to act by controlling the rates of enzyme synthesis. Cis compared with trans action has been tested for those proximate regulatory sites controlling enzymes for which appropriate structural variants exist. The rate of synthesis of beta-galactosidase in mouse tissues is under the control of a regulatory locus; Bgl-s, that is tightly linked to the enzyme structural gene; we have tested the cis/trans nature of Bgl-s action by analysis of the electrophoretic mobility of the enzyme from animals heterozygous for the appropriate regulatory and structural alleles. Our results indicate that Bgl-s acts cis, controlling the expression of the structural gene located on the same chromosome.

Animals↗
PubMed1979

A regulatory locus for mouse beta-glucuronidase induction, Gur, controls messenger RNA activity.

A regulatory locus in a higher organism has been shown to control a specific messenger RNA activity. The Gur locus in mice regulates the production of kidney beta-glucuronidase messenger RNA activity after induction of the beta-glucuronidase structural gene, Gus, by testosterone. beta-Glucuronidase messenger RNA was assayed by its ability to direct the synthesis of catalytically active murine beta-glucuronidase in Xenopus oocytes.

Animals↗
PubMed1979

Genetic determination of the developmental program for mouse liver beta-galactosidase: involvement of sites proximate to and distant from the structural gene.

The identification and mode of action of genetic loci that program gene expression during development are important for understanding differentiation in higher organisms. Previous work from this laboratory has identified two patterns for the postnatal development of liver beta-galactosidase among inbred mouse strains: type I, where activity levels remain constant after about 30 days of age, is found in strains DBA/2J, CBA/J, and BALB/cJ, among others; type II, where activity levels increase between 25 and 50 days of age to reach a new adult level, is found in strain C57BL/6J and related strains. It has been shown that the type I vs. type II developmental difference between strains C57BL/6J and DBA/2J is due to variation at a locus, Bgl-t, that maps with the beta-galactosidase complex, [Bgl], on chromosome 9. In the present study, we have confirmed the existence of Bgl-t as a temporal locus within [Bgl] by analysis of both a congenic strain carrying the beta-galactosidase complex of strain CBA/J in the C57BL/6J genetic background and a cross of strains CBA/J and C57BL/6J. The existence of additional temporal loci for beta-galactosidase that segregate independently of the structural gene and participate in determination of the type I vs. type II difference was revealed by analysis of: (1) a congenic strain containing the beta-galactosidase complex of strain BALB/cJ in the C57BL/10Sn background; (2) recombinant inbred lines derived from progenitor strains C57BL/6ByJ and BALB/cByJ; and (3) a genetic cross between strains C57BL/6ByJ and BALB/cByJ. Thus, for these pairs of strains, the type I vs. type II developmental difference is due to variation at a temporal locus (or loci) unlinked to the enzyme structural gene, and not at Bgl-t. These facts, together with information gathered from an examination of the distribution of beta-galactosidase phenotypes among over 100 inbred strains (Breen, Lusis and Paigen 1977), have led us to conclude that the postnatal developmental pattern for liver beta-galactosidase is determined by a set of interacting temporal genes. One of these, Bgl-t, is located within [Bgl], and one or more are separable from [Bgl] by recombination. A possible mode of interaction among the temporal and instructural loci is suggested.

Animals↗
PubMed1979

Genetic regulation of mup production in recombinant inbred mice.

Inbred strains of mice excrete all three major urinary proteins (mups) when induced by testosterone, but differ as to the relative proportions and total levels of each mup present. We have now determined the urinary mup phenotypes before and after testosterone treatment of seven recombinant inbred strains derived from progenitor strains exhibiting different mup phenotypes. The results confirm previous observations indicating that total control of mup protein production is a multigenic process. One locus, Mup-a on chromosome 4, determines the relative mup protein proportions after induction by testosterone. Mup-a, together with other genetic sites, determines the basal mup proportions. Genes other than Mup-a determine the kinetics of mup induction and total mup excretion.

Alleles↗