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M H Meisler

Publications and source records attributed to M H Meisler.

At least 109 records · Page 6Linked to original sources
PubMed1988

Expression of the human amylase genes: recent origin of a salivary amylase promoter from an actin pseudogene.

The human genes encoding salivary amylase (AMY1) and pancreatic amylase (AMY2) are nearly identical in structure and sequence. We have used ribonuclease protection studies to identify the functional gene copies in this multigene family. Riboprobes derived from each gene were hybridized to RNA from human pancreas, parotid and liver. The sizes of the protected fragments demonstrated that both pancreatic genes are expressed in pancreas. One of the pancreatic genes, AMY2B, is also transcribed at a low level in liver, but not from the promoter used in pancreas. AMY1 transcripts were detected in parotid, but not in pancreas or liver. Unexpected fragments protected by liver RNA led to the discovery that the 5' regions of the five human amylase genes contain a processed gamma-actin pseudogene. The promoter and start site for transcription of AMY1 are recently derived from the 3' untranslated region of gamma-actin. In addition, insertion of an endogenous retrovirus has interrupted the gamma-actin pseudogene in four of the five amylase genes.

Actins↗
PubMed1988

Concerted evolution of human amylase genes.

Cosmid clones containing 250 kilobases of genomic DNA from the human amylase gene cluster have been isolated. These clones contain seven distinct amylase genes which appear to comprise the complete multigene family. By sequence comparison with the cDNAs, we have identified two pancreatic amylase genes and three salivary amylase genes. Two truncated pseudogenes were also recovered. Intergenic distances of 17 to 22 kilobases separate the amylase gene copies. Within the past 10 million years, duplications, gene conversions, and unequal crossover events have resulted in a very high level of sequence similarity among human amylase gene copies. To identify sequence elements involved in tissue-specific expression and hormonal regulation, the promoter regions of the human amylase genes were sequenced and compared with those of the corresponding mouse genes. The promoters of the human and mouse pancreatic amylase genes are highly homologous between nucleotide -160 and the cap site. Two sequence elements thought to influence pancreas-specific expression of the rodent genes are present in the human genes. In contrast, similarity in the 5' flanking sequences of the salivary amylase genes is limited to several short sequence elements whose positions and orientations differ in the two species. Some of these sequence elements are also associated with other parotid-specific genes and may be involved in their tissue-specific expression. A glucocorticoid response element and a general enhancer element are closely associated in several of the amylase promoters.

Amylases↗
PubMed1988

Glucocorticoid and developmental regulation of amylase mRNAs in mouse liver cells.

We characterized alpha-amylase expression in the hepatoma cell line Hepa 1-6 and in normal mouse liver. Both Amy-1 and Amy-2 were expressed in Hepa 1-6 and were regulated by glucocorticoids. Transcription in the hepatoma cells was initiated at the same start sites as in mouse tissues. Glucocorticoid treatment increased the abundance of Amy-1 and Amy-2 transcripts by 10 to 20-fold. This increase was detected within 4 h and was maximal by 24 h. The pattern of amylase expression in this hepatoma cell line accurately reflects amylase expression in the liver in vivo. During liver development, we observed a large increase in the abundance of Amy-1 transcripts just before birth, at a time when circulating glucocorticoids are also elevated. Adult mouse liver expressed Amy-1 and Amy-2 at levels comparable to those of fully induced hepatoma cells. Liver is thus a likely source of both amylase isozymes in mouse serum. These studies demonstrate that Amy-2 expression is not limited to the pancreas but also occurs at a low level in liver cells.

Amylases↗
PubMed1987

Evidence that the same structural gene encodes testicular and adrenal 3 beta-hydroxysteroid dehydrogenase-isomerase.

Thermostability of 3 beta-hydroxysteroid dehydrogenase-isomerase (3 beta HSD) activity was examined in testes and adrenal glands from several inbred lines and feral mice. A thermolabile variant of 3 beta HSD was detected in the feral Brno mice. The thermostability (t1/2) of 3 beta HSD was approximately 7 min for both testes and adrenal glands from C57BL/6J mice, compared with 4 min for both tissues from Brno mice. Comparison of testicular and adrenal 3 beta HSD thermostability in six kinds of mice indicated that the t1/2 of 3 beta HSD was correlated in the two tissues and could be classified into two distinct types, thermolabile and thermostable. In contrast, quantitative variants in 3 beta HSD activity were not correlated in the two tissues. These data are consistent with the hypothesis that testicular and adrenal 3 beta HSD is encoded by the same structural gene but that expression of 3 beta HSD activity is independently controlled in testes and adrenal glands.

3-Hydroxysteroid Dehydrogenases↗
PubMed1987

Tissue-specific and insulin-dependent expression of a pancreatic amylase gene in transgenic mice.

The regulatory properties of mouse pancreatic amylase genes include exclusive expression in the acinar cells of the pancreas and dependence on insulin and glucocorticoids for maximal expression. We have characterized a murine pancreatic amylase gene, Amy-2.2y, whose promoter sequence is 30% divergent from those of previously sequenced amylase genes. To localize sequences required for tissue-specific and hormone-dependent activation, we established two lines of transgenic mice. The first line contained a single copy of the complete Amy-2.2y gene as well as 9 kilobases of 5'-flanking sequence and 5 kilobases of 3'-flanking sequence. The second line carried a minigene which included 208 base pairs of 5'-flanking sequence and 300 base pairs of 3'-flanking sequence. In both lines the transgene was expressed at high levels exclusively in the pancreas. Both constructs were dependent on insulin and induced by dexamethasone. Thus, the transferred genes contained the sequences required for tissue-specific and hormonally regulated expression.

Amino Acid Sequence↗
PubMed1986

Interstrain variation in amylase gene copy number and mRNA abundance in three mouse tissues.

Amylase expression in strain YBR differs in several respects from the standard mouse phenotype. The synthesis of salivary amylase is elevated twofold in YBR mice and the synthesis of pancreatic amylase is reduced to one-half the normal rate. We have compared the concentrations of amylase mRNA in the parotid, liver and pancreas of YBR mice with those in strains A/J and C3H. We observed differences in amylase mRNA abundance which can account for the levels of amylase protein synthesis in the parotid and pancreas of these strains. Unexpectedly, the concentration of amylase mRNA in the liver of YBR mice was also higher than in the other strains. Since liver amylase is transcribed from the same gene as parotid amylase, duplication of the Amy-1 locus could account for the elevated mRNA concentration in both tissues. Quantitative analysis of genomic DNA by Southern blotting provided direct evidence for duplication of Amy-1 in strain YBR.

Animals↗
PubMed1986

Simultaneous expression of salivary and pancreatic amylase genes in cultured mouse hepatoma cells.

The tissue-specific expression of two types of mouse amylase genes does not overlap in vivo; the Amy-1 locus is transcribed in the parotid gland and the liver, while expression of Amy-2 is limited to the pancreas. We identified a mouse hepatoma cell line, Hepa 1-6, in which both amylase genes can be simultaneously expressed. Amy-1 is constitutively active in these cells and is inducible by dexamethasone at the level of mRNA. We demonstrated that the liver-specific promoter of Amy-1 is utilized by the dexamethasone-treated hepatoma cells, and that glucocorticoid consensus sequences are present upstream of this promoter. Amy-2 is not detectable constitutively, but can be activated if the cells are cultured in serum-free medium containing dexamethasone. Expression of Amy-2 in a nonpancreatic cell type has not previously been observed. We speculate that induction of Amy-1 and activation of Amy-2 may involve different regulatory mechanisms. Hepa 1-6 cells provide an experimental system for molecular analysis of these events.

Amylases↗
PubMed1986

Assignment of pancreatic ribonuclease gene to mouse chromosome 14.

A pancreatic ribonuclease cDNA was used as a probe for Southern blot hybridization of genomic DNA from recombinant inbred strains of mice. The results indicated that the gene coding for pancreatic ribonuclease (Rib-1) can be assigned to mouse chromosome 14. Analysis of the congenic strain B10.D2(57N)Sn confirmed this assignment and indicated that Rib-1 is closely linked to the genes encoding the T-cell receptor alpha subunit (Tcra) and nucleoside phosphorylase-2 (Np-2).

Alleles↗
PubMed1986

Genes encoding pancreatic polypeptide and neuropeptide Y are on human chromosomes 17 and 7.

Pancreatic polypeptide and neuropeptide Y share 50% amino acid homology (18 out of 36 residues), suggesting that they may have common ancestral origins. cDNA clones complementary to human mRNAs encoding pancreatic polypeptide and neuropeptide Y were used to detect specific human genomic DNA sequences in human-mouse somatic cell hybrid lines. The pancreatic polypeptide gene (PPY) segregated with human chromosome 17, while the neuropeptide Y gene (NPY) segregated with human chromosome 7. Examination of cell hybrids with chromosomal rearrangements assigned PPY to the p11.1-qter region and NPY to the pter-q22 region of their respective chromosomes.

Amino Acid Sequence↗
PubMed1985

Evolution of the amylase multigene family. YBR/Ki mice express a pancreatic amylase gene which is silent in other strains.

The two isozymes of pancreatic amylase in mouse strain YBR/Ki are encoded by closely linked genes which are independently regulated. We have isolated these two pancreatic amylase genes, Amy-2.1 and Amy-2.2, from a cosmid library of YBR/Ki genomic DNA and compared the nucleotide sequences of coding regions with the amino acid sequences of the protein isozymes. Transcripts of both genes were also isolated from a pancreatic cDNA library and partially sequenced. The results demonstrate that Amy-2.1 encodes the A1 isozyme of YBR/Ki pancreatic amylase, while Amy- 2.2 encodes the insulin-dependent B1 isozyme. Similarities of restriction maps and nucleotide sequences suggest that Amy-2.1 is closely related to the active Amy-2a gene previously isolated from strain A/J (Schibler, U., Pittet, A.-C., Young, R. A., Hagenbüchle, O., Tosi, M., Gellman, S., and Wellauer, P. K. (1982) J. Mol. Biol. 155, 247-266). Expression of Amy-2.2 may be limited to strain YBR/Ki. The inactive Amy-X gene from A/J (Schibler, U., Pittet, A.-C., Young, R. A., Hagenbüchle, O., Tosi, M., Gellman, S., and Wellauer, P. K. (1982) J. Mol. Biol. 155, 247-266) is apparently a null allele of Amy-2.2. An additional amylase gene from YBR/Ki has been identified as a pancreatic amylase pseudogene which diverged between sixteen and thirty-two million years ago. The pancreatic amylase subfamily in strain YBR/Ki thus consists of two active genes and one pseudogene. The low rate of amylase production in YBR/Ki pancreas, relative to that of other inbred strains, can be accounted for by the lower number of gene copies in this strain. Comparison of pancreatic amylase genes from different inbred strains provides evidence for several duplication and deletion events during the recent evolution of this chromosome region.

Amylases↗
PubMed1985

A 78-kilobase region of mouse chromosome 3 contains salivary and pancreatic amylase genes and a pseudogene.

Genetic studies have demonstrated that salivary and pancreatic amylase genes are closely linked in human and mouse. To analyze the arrangement of genes within the amylase cluster, a library of YBR mouse genomic DNA was cloned in the cosmid vector pJB8. Clones containing amylase genes were identified by hybridization with amylase cDNA probes. Salivary and pancreatic amylase genes were isolated on separate cosmid clones, but no overlapping clones were evident from the initial screening. A strategy for the rapid isolation of terminal noncoding fragments from the cosmid clones was developed. By using these terminal fragments for chromosome "walking," a map of 78 kilobases of the amylase gene region was constructed. The salivary and pancreatic amylase genes are present within this region in the same 5'-to-3' orientation, separated by 22 kilobases of genomic DNA. A truncated amylase pseudogene is located 10 kilobases downstream from the pancreatic amylase gene.

Amylases↗
PubMed1984

Independent regulation of nonallelic pancreatic amylase genes in diabetic mice.

Administration of streptozotocin produces a diabetic condition in mice characterized by a specific decrease in amylase synthesis in the pancreas as well as a substantial reduction in amylase mRNA concentration. We have studied this effect in mice of the congenic strains C3H.AmyYBR and C3H.AmyCE with multiple active copies of the pancreatic amylase structural gene. When mice of these strains are treated with streptozotocin, the magnitude of reduction in the synthesis of each amylase isozyme is different. These differences are reflected in the relative activities of isozyme-specific mRNAs in an in vitro translation assay. Administration of insulin results in partial restoration of normal phenotypes. The results provide genetic evidence that individual copies of the amylase structural gene are associated with divergent cis-acting insulin-responsive sequences.

Alleles↗
PubMed1984

Conserved linkage within a 4-cM region of mouse chromosome 9 and human chromosome 11.

A six-point cross was carried out to determine the gene order and distances among loci on mouse chromosome 9. Our results are consistent with the following arrangement: centromere - Lap-1 - (1.2 +/- 0.8) - Es-17 - (3.0 +/- 1.0) - Ups - (1.3 +/- 0.7) - Alp-1 - (23.1 +/- 3.4) - Mod-1 - (10.9 +/- 2.6) - Acy-1. This study provides the first estimate of the distances between Es-17, Ups and Alp-1. Exceptions to the preferred association of alleles of Es-17 and Ups have been found in three feral populations and one inbred strain. Evidence is presented for the homology of this chromosome region with the ESA4 - UPS - APO-AI region on the long arm of human chromosome 11.

Acetylesterase↗
PubMed1982

Linkage of the structural gene for uroporphyrinogen I synthase to markers on mouse chromosome 9 in a cross between feral and inbred mice.

The Ups locus has been mapped to mouse chromosome 9 in a three-point cross. The observed gene order is centromere-Ups-15-Mpi-1-22-Mod-1. Ups is unlinked to Lv, which encodes the previous enzyme in the heme biosynthesis pathway. Feral mice collected at Skive, Denmark, have been characterized at several biochemical loci; multiple differences from inbred strains make this a useful stock for linkage analysis.

Alleles↗
PubMed1982

Separation of allelic variants by two-dimensional electrophoresis.

The resolving power of two-dimensional (2-D) gel electrophoresis has been tested using 17 allele products at five loci. Standard O'Farrell gels could separate 13 of these isozymes. The addition of a second pH gradient made it possible to separate all but one of the variant proteins. These results indicate that 2-D gel electrophoresis can resolve more than 90% of variants originally detected by one-dimensional (1-D) electrophoresis. The implications of these results for the low estimates of average heterozygosity obtained in surveys using 2-D gel electrophoresis are discussed.

Alleles↗
PubMed1981

Testosterone effects on the induction and urinary excretion of mouse kidney glycosphingolipids associated with lysosomes.

Male C57BL/6J mice were shown to excrete in their urine approximately 50 times as much glycolipid as do female mice. These lipids were primarily galabiglycosylceramides and globotriglycosylceramides which contained nonhydroxy and hydroxy fatty acids, sphingosine, and phytosphingosine as components of their ceramide moieties. The lipids were shown to be associated with multilamellar bodies. Neutral glycosphingolipids from kidney and urine were separated and analyzed by high performance liquid chromatographic techniques. Male kidneys were shown to contain about twice as much neutral glycosphingolipid as female kidneys. The female kidneys were virtually devoid of galactosylceramides and galabiglycosylceramides. Implantation of testosterone pellets in female mice resulted in a concomitant increase in urinary glycosphingolipids (greater than 100-fold) and in urinary lysosomal enzymes (about 10-fold). In mutant light ear mice, which are defective in excretion of lysosomal enzymes, the urinary excretion of glycolipids is also blocked. Taken together these data suggest that testosterone induces the formation of multilamellar kidney lysosomes which contain a complement of glycosphingolipids and which are normally excreted in the urine.

Animals↗
PubMed1981

Genetic determination of amylase synthesis in the mouse.

Extensive genetic variation in structure and rate of synthesis of pancreatic amylase has been identified among strains of mice. The relative rate of synthesis of amylase varies from 0.15 in strain YBR to 0.26 in strain C3H. The number of electrophoretic isozymes of pancreatic amylase varies between one and four. In each strain with multiple amylase isozymes, a characteristic quantitative distribution of protein among the isozymes is observed. Isozyme proportions are determined by the relative rates of synthesis of each component. Congenic lines with different amylase phenotypes have been established. Genetic analysis reveals the close linkage of cis-acting sites determining rate of synthesis and electrophoretic mobility of mouse pancreatic amylase.

Amylases↗