Search PubMed⌕ Search

Biomedical subjects

W A Held

Publications and source records attributed to W A Held.

At least 37 records · Page 2Linked to original sources
PubMed1994

Chromosome 8 alterations accompany tumorigenesis in renin-SV40 T antigen transgenic mice.

s.c. and abdominal tumors from interspecific hybrid, transgenic mice containing the SV40 early region linked to a renin enhancer/promoter were analyzed for loss of heterozygosity to identify chromosomal regions involved in tumorigenesis. A very high frequency of loss of heterozygosity/partial loss of heterozygosity or allelic imbalance involving the distal regions of chromosome 8 was observed in the s.c. tumors (76%) with frequent amplification (3-6 times) of the corresponding proximal regions including Junb, suggesting that chromosome 8 breakage and amplification promotes tumorigenesis in these mice.

Animals↗
PubMed1992

Reactivation of insulin-like growth factor II during hepatocarcinogenesis in transgenic mice suggests a role in malignant growth.

We have studied the expression of insulin-like growth factor II (IGF-II) during hepatocarcinogenesis in four independent transgenic mouse lines. In all four lines liver-directed transgene expression induces a stepwise and relatively synchronized tumorigenesis. IGF-II reexpression occurs in all four lines irrespective of the mechanism of tumor induction. Reexpression is chronologically associated with late progression steps toward hepatocellular carcinoma and correlated with the respective tumor progression rate in each line. IGF-II activation is focal and topographically associated with high replicative activity. IGF-II mRNAs in hepatocellular carcinomas show similarities to the expression pattern in fetal liver, and a M(r) 15,000 IGF-II polypeptide accumulates intracellularly in distinct cytoplasmic preferentially perinuclear compartments. These data indicate that IGF-II reexpression is a marker for progression to hepatocellular carcinoma and may contribute to hepatocarcinogenesis via an autocrine mechanism.

Animals↗
PubMed1991

Selective amplification of periportal transitional cells precedes formation of hepatocellular carcinoma in SV40 large tag transgenic mice.

In a major urinary protein (MUP)-promoter/simian virus 40 (SV40)Tag transgenic mouse line (MT-D2) the liver-directed, androgen-regulated transgene expression leads to synchronized pathology resulting in a stepwise progression to multiple hepatocellular carcinomas. SV40Tag-activated replication gives rise to two different preneoplastic alterations in hepatocytes, which are characterized in detail: 1) dysplasia and finally cell death in the original hepatocyte population and 2) amplification of periportal transitional hepatocytes leading to multifocal hyperplasia and hepatocellular carcinoma. Multifocal hyperplasia, most probably the equivalent of SV40Tag-immortalization, grows confluent and leads to hepatomegaly. SV40Tag-independent, secondary events are necessary for the tumor development from confluent hyperplasia. This allows further investigation of the steps involved in malignant transformation and progression during hepatocarcinogenesis in vivo.

Animals↗
PubMed1989

T antigen expression and tumorigenesis in transgenic mice containing a mouse major urinary protein/SV40 T antigen hybrid gene.

A hybrid mouse major urinary protein (MUP)/SV40 T antigen gene was microinjected into fertilized mouse embryos and the resulting transgenic mice analyzed for the regulated expression of the transgene. Available evidence indicates that the MUP gene used for the hybrid gene construct is expressed in both male and female liver and possibly mammary gland. Three different transgenic lines exhibited a consistent pattern of tissue specific expression of the transgene. As a consequence of transgene expression and T antigen synthesis in the liver, both male and female transgenic animals developed liver hyperplasia and tumors. Transgene expression and liver hyperplasia commenced at approximately 2-4 weeks of age, the same time that MUP gene expression is first detected in the liver. The expression of the transgene resulted in an immediate strong suppression of liver MUP mRNA levels but had relatively little effect on other liver specific mRNAs. From 4 to 8 weeks, the liver increased several fold in size, relative to non-transgenic littermates. Definitive tumor nodules were not apparent until 8-10 weeks. The transgene was also consistently found to be expressed in the skin sebaceous glands and the preputial gland, a modified sebaceous gland. The expression of the transgene in the skin sebaceous glands is consistent with the presence of MUP mRNA in the skin and a putative role for MUPs in the transport and excretion of small molecules. Occasional expression of the transgene in other tissues (kidney and mammary connective tissues) was also noted.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Identification and characterization of functional genes encoding the mouse major urinary proteins.

Mouse Ltk- cells were stably transfected with cloned genes encoding the mouse major urinary proteins (MUPs). C57BL/6J MUP genomic clones encoding MUP 2 (BL6-25 and BL6-51), MUP 3 (BL6-11 and BL6-3), and MUP 4 (BL6-42) have been identified. In C57BL/6J mice, MUP 2 and MUP 4 are known to be synthesized in male, but not female, liver, and MUP 3 is known to be synthesized in both male and female liver and mammary gland. A BALB/c genomic clone (BJ-31) was shown to encode a MUP that is slightly more basic than MUP 2 and was previously shown to be synthesized in both male and female liver of BALB/c but not C57BL/6 mice. Comigration on two-dimensional polyacrylamide gels of the MUPs encoded by the transfecting gene provides a basis for tentative identification of the tissue specificity and mode of regulation of each gene. DNA sequence analysis of the 5' flanking region indicates that the different MUP genes are highly homologous (0.20 to 2.40% divergence) within the 879 base pairs analyzed. The most prominent differences in sequence occur within an A-rich region just 5' of the TATA box. This region (from -47 to -93) contains primarily A or C(A)N nucleotides and varies from 15 to 46 nucleotides in length in the different clones.

Animals↗
PubMed1986

Effects of Schistosoma mansoni on androgen regulated gene expression in the mouse.

Two-dimensional gel electrophoresis of liver mRNA translation products and dot-blot hybridization revealed that the levels of mRNA encoding major urinary proteins were greatly reduced in mice infected with Schistosoma mansoni. Major urinary protein mRNA levels are known to be androgen regulated. Dot-blot hybridization analysis of RNAs from various mouse tissues with a variety of cDNA probes indicated that all androgen-regulated mRNAs tested were reduced in infected mice. Administration of testosterone to infected animals restored urinary major urinary protein levels. Direct measurement of serum testosterone levels and seminal vesicle weights confirmed that chronic schistosome infection reduces testosterone to castration levels in male mice.

Animals↗
PubMed1985

Rat alpha 2u-globulin mRNA expression in the preputial gland.

Rat alpha 2u-globulin and the mouse major urinary proteins (MUP) are encoded by homologous multigene families whose members exhibit diverse tissue-specific, developmental, and hormonal controls of expression. Although their patterns of expression and hormonal control appear to be very similar in many respects, we have found high levels of alpha 2u-globulin mRNA in rat preputial glands, whereas MUP mRNA could not be detected in the male mouse preputial gland. Male and female rat preputial have similar concentrations of alpha 2u-globulin mRNA, suggesting an absence of endocrine regulation as occurs in the liver and lachrymal glands. Two-dimensional polyacrylamide gel electrophoresis of proteins encoded by hybrid-selected alpha 2u-globulin mRNA indicates that the liver and lachrymal translation products have different mobilities. However, many of the preputial gland products comigrate with most or all of the liver and lachrymal products. Among the possibilities suggested by these results is that alpha 2u-globulin genes expressed in liver and lachrymal glands under endocrine control are also expressed constitutively in the preputial gland.

Alpha-Globulins↗
PubMed1985

Variation in the major urinary protein multigene family in wild-derived mice.

The levels of expression and genomic organization of genes coding for the major urinary proteins (MUPs) were examined in several stocks of wild-derived mice. Levels of MUP mRNA in the liver varied considerably with M. musculus Brno and M. castaneus males having several-fold more MUP RNA than inbred C57BL/6 males, whereas M. hortulanus, M. caroli and M. cervicolor displayed levels much lower than C57BL/6. Analysis of RNA with MUP cDNAs specific to two different subfamilies of MUP genes revealed that M. caroli and M. cervicolor primarily expressed a MUP mRNA that was less abundant in C57BL/6, suggesting differential expression of subfamilies of genes within the MUP multigene complex. Although inbred males usually have five-fold more MUP mRNA than inbred females, male to female ratios for wild-derived stocks ranged from one to several hundred. Southern blots of genomic DNA hybridized to MUP subfamily probes revealed differences in restriction fragment sizes as well as possible variation in the number of MUP genes in some species. Analysis of urinary proteins from hybrids between C57BL/6 and M. spretus suggested that low MUP expression in M. spretus females was due to cis-acting genetic elements.

Animals↗
PubMed1984

Subfamilies of the mouse major urinary protein (MUP) multi-gene family: sequence analysis of cDNA clones and differential regulation in the liver.

The mouse major urinary proteins (MUPs) are the products of a multi-gene family of 30-35 genes whose members exhibit diverse tissue specific, developmental, and hormonal controls. Three cDNA clones corresponding to liver MUP mRNAs have been sequenced. Two of the clones (p499, C57BL/6 and p1057, BALB/c) share strong homology whereas a third clone (p199, C57BL/6) has diverged considerably from the others at the nucleic acid (85% homology) and protein (68% homology) levels. The 5' regions of p499 and p199 which show the most sequence divergence were subcloned and shown to hybridize to different liver MUP mRNAs. The p499-5' sequence was expressed in all MUP expressing tissues (liver, lachrymal, submaxillary and mammary) whereas the p199-5' sequence was expressed primarily in the liver and lachrymal. Analysis of liver RNA from mice in different endocrine states indicates that the p499-5' sequence is strongly regulated by thyroxine administration whereas the p199-5' sequence is not. Both sequences appear to be regulated by growth hormone and testosterone. Southern blot analysis of mouse genomic DNA indicates that there are multiple genes homologous to each sequence.

Animals↗
PubMed1984

The acute phase response of mouse liver. Genetic analysis of the major acute phase reactants.

We have examined changes in translatable liver mRNAs during the acute phase response in several inbred mouse strains. Induction of mRNAs for the known acute phase reactants serum amyloid A, hemopexin, haptoglobin, and alpha 1-acid glycoprotein was observed. Two alpha 1-acid glycoproteins, termed AGP-1 and AGP-2, differing in size and charge, were found in all mice and appear to derive from distinct yet closely related mRNAs. Polymorphism in the structure of AGP-1 among strains was used to map the structural gene, Agp-1, to chromosome 4 near the b locus. Structural variation for serum amyloid A enabled mapping its structural gene, S alpha alpha, to chromosome 7, near Gpi-1. A wild-derived population of mice, Mus spretus, contains several variations of interest, including structural variations in many acute phase proteins and a putative regulatory variation specific to AGP-1. Further analysis of these genetic variants should provide novel insights into the acute phase response and the factors that mediate it.

Animals↗
PubMed1983

The gene family for major urinary proteins: expression in several secretory tissues of the mouse.

The major urinary proteins (MUPs) of the mouse are encoded by a multigene family located at the Mup a locus on chromosome 4. Previous investigations have shown that the MUPs are synthesized in the liver, secreted and then excreted in the urine. We have found significant levels of MUP mRNA in several secretory tissues: the liver and the submaxillary, lachrymal and mammary glands. There are striking differences in hormonal and developmental regulation of MUP gene expression in these tissues. Furthermore, each tissue appears to express a characteristic pattern of MUP mRNAs. In particular, the lachrymal glands appear to express an entirely different set of MUP mRNAs. These results are discussed in relation to the organization of the MUP gene cluster and a possible function of the MUPs.

Animals↗
PubMed1983

Differential, multihormonal regulation of the mouse major urinary protein gene family in the liver.

The hormonal requirements for the regulation of the major urinary protein (MUP) mRNA levels in mouse liver have been examined. Previous experiments have shown that administration of testosterone to female or castrated male mice increases MUP mRNA levels approximately fivefold to normal male levels. We have found that thyroxine and the peptide hormone, growth hormone, each had a pronounced effect on MUP mRNA levels. MUP mRNA was reduced 150-fold in growth-hormone-deficient mutant mice (little). The administration of growth hormone and thyroxine induced MUP mRNA approximately 150-fold, and when administered together, they induced MUP mRNA approximately 1,000-fold. testosterone administration. When administered separately to these mice, growth hormone and thyroxine induced with MUP mRNA approximately 150-fold, and when administered together, they induced MUP mRNA approximately 1,000-fold. Testicular feminized mice, which lack a functional major testosterone receptor protein, can also be induced to male levels by treatment with both growth hormone and thyroxine. In addition, we present evidence which indicates that growth hormone, thyroxine, and testosterone differentially regulate the levels of distinct MUP mRNA species.

Animals↗
PubMed1983

Characterization of mutants of herpes simplex viruses, types 1 and 2, that produce fragments of the thymidine kinase polypeptide.

Seven tk- mutants of herpes simplex virus, type 2 (HSV-2), and three tk- mutants of herpes simplex virus, type 1 (HSV-1), were isolated which did not produce the thymidine kinase (TK) polypeptides but formed smaller polypeptides not seen in wild-type infected cells. Positive TK mRNA selection by hybridization to the cloned tk genes followed by in vitro translation identified the TK polypeptides. Comparisons of the products of partial proteolysis of the polypeptides of four HSV-2 and two HSV-1 tk- mutants to those of the parental TK polypeptides indicated that, in each case, the novel polypeptide was a fragment of the TK polypeptide, showing that these mutants have defects in the structural gene for tk. HSV-2 mutants of this sort have not been previously described. They and the HSV-1 mutants are similar to HSV-1 mutants reported previously. In addition, it was found that TK mRNA was present early in infection but was absent late in infection, suggesting that the shutoff of TK synthesis is due to message degradation. Also, HSV-2 TK mRNA did not hybridize to the cloned HSV-1 tk gene indicating that these genes have extensively diverged.

Chymotrypsin↗
PubMed1981

Biosynthesis and hormone-regulated expression of secretory glycoproteins in rat liver and hepatoma cells. Effect of glucocorticoids and inflammation.

Exposure of rat hepatoma tissue culture cells to dexamethasone results in appearance of a new glycoprotein, gp35-50 (Mr = 35,000 to 50,000) and increased synthesis of another glycoprotein, gp50 (Mr = 50,000). The glycoproteins synthesized in a fractionated cell-free translation system (containing dog pancreas microsomes) appear as a well separated series of spots on two-dimensional polyacrylamide gels which differ in size and charge. Glycoproteins synthesized by glucose-starved cells show similar size and charge heterogeneity. The size heterogeneity consists of a series of spots, each differing in molecular weights by about 3,000, which could be almost completely abolished by treatment with endo-beta-N-acetylglucosaminidase H. Our results indicate that unglycosylated gp50 (Mr = 42,000) typically acquires 3 N-glycan units, whereas gp35-50 (Mr = 22,000) possesses eight N-glycosylation sites. Analysis of the cell-free translation products directed by mRNA from hepatoma tissue culture cells grown in tissue culture, from hepatoma tissue, and from normal liver tissue indicated that administration of dexamethasone causes a pronounced increase in gp35-50 mRNA in all three tissues. A similar increase was observed in liver after inflammation which along with other biochemical properties suggests that gp35-50 may be alpha 1-acid protein. In contrast, mRNA coding for gp50 was not increased by dexamethasone in tumor tissue and no protein structurally related to gp50 was detected in the liver mRNA translation products. Thus, gp35-50 is expressed in normal liver, whereas gp50 is expressed in hepatoma cells and is differentially regulated by steroid hormones depending on whether the cells are grown in tissue culture or as a tumor in the rat.

Animals↗
PubMed1979

An abundant androgen-regulated mRNA in the mouse kidney.

We have identified an abundant 20,000 dalton protein (KAP) by in vitro translation of male mouse kidney mRNA. This protein is synthesized in reduced amounts from female kidney mRNA. A KAP cDNA fragment was purified and used for nucleic acid hybridization studies. Females and castrated males have 10 and 200 fold lower levels, respectively, of KAP mRNA relative to males. The administration of testosterone to females or castrated males results in the induction of KAP mRNA to normal male levels. Testicular feminized (Tfm) mice have 3 fold lower levels of KAP mRNA relative to normal males and are not induced by testosterone. KAP mRNA is not found in significant amounts in tissues other than the kidney, and the KAP gene renatures with kinetics similar to single-copy DNA. With the rapidly expanding knowledge of mouse genetics, KAP should prove useful in determining genetic factors which regulate the inducibility and tissue specificity of a hormonally regulated gene.

Alleles↗