Subfamily of submaxillary gland-specific Mup genes: chromosomal linkage and sequence comparison with liver-specific Mup genes

The major urinary protein gene cluster knockout mouse as a novel model for translational metabolism research

Scientific evidence suggests that not only murine scent communication is regulated by major urinary proteins, but that their expression may also vary in response to metabolism via a yet unknown mechanism. Major urinary proteins are expressed mainly in the liver, showing a sexually dimorphic pattern with substantially higher expression in males. Here, we investigate the metabolic implications of a major urinary protein knockout in twelve-week-old male and female C57BL/6N mice during ad libitum feeding. Despite both sexes of major urinary protein knockout mice displayed numerically increased body weight and visceral adipose tissue proportions compared to sex-matched wildtype mice, the main genotype-specific metabolic differences were observed exclusively in males. Male major urinary protein knockout mice exhibited plasma and hepatic lipid accumulation accompanied by a hepatic transcriptome indicating an activation of lipogenesis. These findings match the higher major urinary protein expression in male compared to female wildtype mice, suggesting a more distinct reduction in energy requirements in male compared to female major urinary protein knockout mice. The observed sex-specific anabolic phenotype confirms a role of major urinary protein in metabolism and, since major urinary proteins are not expressed in humans, suggests the major urinary protein knockout mouse as a potential alternative model for translational metabolism research which needs to be further elucidated.

Taenia crassiceps cysticercosis: variations in its parasite growth permissiveness that encounter with local immune features in BALB/c substrains

This study describes the first days of Taenia crassiceps infection in BALB/c substrains, BALB/cAnN and BALB/cJ, using two stocks of the same strains which were kept in different animal facilities, conventional and pathogen-free conditions, respectively. This study shows that parasite growth restriction shown by conventional BALB/cJ mice changed to parasite growth permissiveness when pathogen-free BALB/cJ mice were used. In addition, the higher number of macrophages, NK cells and intraperitoneal level of IFN-gamma found in the conventional restrictive BALB/cJ substrain vanished when the permissiveness to the parasite growth increased. No differences were found in DNA sequences of parasites collected before and after the change in the permissiveness to parasite growth which favors the possibility that the observed modifications could be due to changes in the murine strains and/or their maintenance conditions.

Differential screening identifies transcripts with depot-dependent expression in white adipose tissues

Background

The co-morbidities of obesity are tied to location of excess fat in the intra-abdominal as compared to subcutaneous white adipose tissue (WAT) depot. Genes distinctly expressed in WAT depots may impart depot-dependent physiological functions. To identify such genes, we prepared subtractive cDNA libraries from murine subcutaneous (SC) or intra-abdominal epididymal (EP) white adipocytes.

Results

Differential screening and qPCR validation identified 7 transcripts with 2.5-fold or greater enrichment in EP vs. SC adipocytes. Boc, a component of the hedgehog signaling pathway demonstrated highest enrichment (~12-fold) in EP adipocytes. We also identified a dramatic enrichment in SC adipocytes vs. EP adipocytes and in SC WAT vs. EP WAT for transcript(s) for the major urinary proteins (Mups), small secreted proteins with pheromone functions that are members of the lipocalin family. Expression of Boc and Mup transcript was further assessed in murine tissues, adipogenesis models, and obesity. qPCR analysis reveals that EP WAT is a major site of expression of Boc transcript. Furthermore, Boc transcript expression decreased in obese EP WAT with a concomitant upregulation of Boc transcript in the obese SC WAT depot. Assessment of the Boc binding partner Cdon in adipose tissue and cell fractions thereof, revealed transcript expression similar to Boc; suggestive of a role for the Boc-Cdon axis in WAT depot function. Mup transcripts were predominantly expressed in liver and in the SC and RP WAT depots and increased several thousand-fold during differentiation of primary murine preadipocytes to adipocytes. Mup transcripts were also markedly reduced in SC WAT and liver of ob/ob genetically obese mice compared to wild type.

Conclusion

Further assessment of WAT depot-enriched transcripts may uncover distinctions in WAT depot gene expression that illuminate the physiological impact of regional adiposity.

Major urinary proteins, alpha(2U)-globulins and aphrodisin

The major urinary proteins (MUPs) are proteins secreted by the liver and filtered by the kidneys into the urine of adult male mice and rats, the MUPs of rats being also referred to as alpha(2U)-globulins. The MUP family also comprises closely related proteins excreted by exocrine glands of rodents, independently of their sex. The MUP family is an expression of a multi-gene family. There is complex hormonal and tissue-specific regulation of MUP gene expression. The multi-gene family and its outflow are characterized by a polymorphism which extends over species, strains, sexes, and individuals. There is evidence of evolutionary conservation of the genes and their outflow within the species and evidence of change between species. MUPs share the eight-stranded beta-barrel structure lining a hydrophobic pocket, common to lipocalins. There is also a high degree of structural conservation between mouse and rat MUPs. MUPs bind small natural odorant molecules in the hydrophobic pocket with medium affinity in the 10(4)-10(5) M(-1) range, and are excreted in the field, with bound odorants. The odorants are then released slowly in air giving a long lasting olfactory trace to the spot. MUPs seem to play complex roles in chemosensory signalling among rodents, functioning as odorant carriers as well as proteins that prime endocrine reactions in female conspecifics. Aphrodisin is a lipocalin, found in hamster vaginal discharge, which stimulates male copulatory behaviour. Aphrodisin does not seem to bind odorants and no polymorphism has been shown. Both MUPs and aphrodisin stimulate the vomeronasal organ of conspecifics.

Isolation of monochromosomal hybrids for mouse chromosomes 3, 6, 10, 12, 14, and 18

Mouse/human somatic cell hybrids constitute a valuable resource for both genetic and physical mapping. In this report, we describe the production and characterization of a series of six monochromosomal hybrids generated by fusion of murine micro-cells with intact human recipient cells. The presence of each mouse chromosome was characterized by PCR analysis and the integrity of the mouse chromosome retained in the hybrids confirmed by fluorescence in situ hybridization (FISH) analysis.

Odorant-binding proteins

Odorant-binding proteins (OBPs) are low-molecular-weight soluble proteins highly concentrated in the nasal mucus of vertebrates and in the sensillar lymph of insects. Their affinity toward odors and pheromones suggests a role in olfactory perception, but their physiological function has not been clearly defined. Several members of this class of proteins have been isolated and characterized both in insects and vertebrates; in most species two or three types of OBPs are expressed in the nasal area. Vertebrates OBPs show significant sequence similarity with a superfamily of soluble carrier proteins called lipocalins. They include some proteins of particular interest that are thought to be involved in the mechanism of releasing and modulating chemical messages with pheromonal activity. The data on vertebrate OBPs are here reviewed together with the most relevant information on related proteins. Theories and models of the physiological functions of odorant-binding proteins are presented and discussed.

Application of electrospray ionization mass spectrometry with maximum-entropy analysis to allelic 'fingerprinting' of major urinary proteins

Mixtures of a specific group of proteins, the major urinary proteins (MUPs), believed to have a role in odorant binding, have been analysed by electrospray ionization mass spectrometry. The data obtained from conventional transformed electrospray data confirm that the molecular weights of the protein mixtures, deduced from published sequences, lie in the molecular weight range 18,600 to 19,000 Da. Application of maximum-entropy analysis to the raw electrospray data has confirmed a heterogeneity in MUP composition, consistent with allelic similarities (and differences) between the different mouse strains. This work demonstrates the use of maximum entropy in the assessment of protein content and in the subsequent resolution enhancement of naturally occurring protein mixtures containing components of closely similar molecular mass.

Silent and expressed sister Mup genes are located within distinct chromatin domains: analysis by pulsed-field gel electrophoresis and polymerase chain reaction-supplemented DNase I digestion

We have recently described a subfamily of two genes, Mup-1.5a and Mup-1.5b, which exist as a nonallelic pair in most inbred strains of mice. The Mup-1.5a and Mup-1.5b genes are more than 99.9% homologous, yet they are differentially expressed. While the Mup-1.5a gene is expressed at a high level in the submaxillary gland, the Mup-1.5b gene does not appear to be expressed either in this or in any other tissue. The Mup-1.5b gene can, however, be expressed as a transgene with the tissue specificity of its sister gene, Mup-1.5a. We have shown before that both the Mup-1.5a and Mup-1.5b genes are located on chromosome 4, closely linked to the Mup-1 locus. In this report, we demonstrate the two genes are located within distinct chromosomal domains, separated by at least 150 to 200 kb of DNA. Using a novel method, detailed in this report, we show that in the submaxillary gland, the Mup-1.5a gene is five- to sixfold more susceptible to DNase I digestion than is the Mup-1.5b gene. This finding suggests that the inactivity of the Mup-1.5b gene is brought about by long range-acting mechanisms that establish a chromatin structure in the vicinity of this gene incompatible with transcription.

Silent and expressed sister Mup genes are located within distinct chromatin domains: analysis by pulsed-field gel electrophoresis and polymerase chain reaction-supplemented DNase I digestion

We have recently described a subfamily of two genes, Mup-1.5a and Mup-1.5b, which exist as a nonallelic pair in most inbred strains of mice. The Mup-1.5a and Mup-1.5b genes are more than 99.9% homologous, yet they are differentially expressed. While the Mup-1.5a gene is expressed at a high level in the submaxillary gland, the Mup-1.5b gene does not appear to be expressed either in this or in any other tissue. The Mup-1.5b gene can, however, be expressed as a transgene with the tissue specificity of its sister gene, Mup-1.5a. We have shown before that both the Mup-1.5a and Mup-1.5b genes are located on chromosome 4, closely linked to the Mup-1 locus. In this report, we demonstrate the two genes are located within distinct chromosomal domains, separated by at least 150 to 200 kb of DNA. Using a novel method, detailed in this report, we show that in the submaxillary gland, the Mup-1.5a gene is five- to sixfold more susceptible to DNase I digestion than is the Mup-1.5b gene. This finding suggests that the inactivity of the Mup-1.5b gene is brought about by long range-acting mechanisms that establish a chromatin structure in the vicinity of this gene incompatible with transcription.

Characterization of mouse-hamster somatic cell hybrids by PCR: a panel of mouse-specific primers for each chromosome

Mouse/hamster somatic cell hybrids form a valuable resource for mouse gene mapping. Characterization of these hybrids by isozyme analysis can be technically demanding and time-consuming. Species-specific polymerase chain reaction (PCR), where a mouse gene but not its homolog in the hamster is amplified, can provide an alternative means of characterization. Mouse-specific primers have been designed for at least one gene on each of the mouse autosomes and the X Chromosome (Chr). Primers are chosen to correspond to untranslated regions of the mouse gene concerned, in order to decrease the chance of cross-hybridization with the homologous hamster gene. These primer sequences are presented, together with the conditions for their use.

Identification of an enhancer required for the expression of a mouse major urinary protein gene in the submaxillary gland

The MUP1.5b gene was previously found to be expressed specifically in the submaxillary gland and at high levels when introduced into mice as a transgene including 4.7 kb of 5'-flanking DNA and 0.3 kb of 3'-flanking DNA. To localize regulatory elements responsible for this tissue-specific pattern of expression, we tested the expression of three additional MUP1.5b transgenes including various amounts of 5'-flanking DNA. These experiments indicated that sequences between -1.85 and -3.46 kb from the transcription initiation site were required for high-level expression in the submaxillary gland. The presence of regulatory elements in this region was also suggested by the detection of a DNase I-hypersensitive site, seen only in submaxillary gland nuclei, at position -2.5 kb upstream from the MUP1.5a gene, a member of the same MUP gene subfamily and virtually identical to the MUP1.5b gene. Further evidence for enhancer activity was provided by the ability of the 1.6-kb DNA fragment including sequences between -1.85 and -3.46 kb to stimulate the expression of an otherwise inactive MUP1.5b-chloramphenicol acetyltransferase fusion gene specifically in the submaxillary gland. The nucleotide sequence of this 1.6-kb DNA fragment was found to be identical for the MUP1.5a and MUP1.5b genes. Together, these results provide the first localization of a cis-acting regulatory sequence involved in the differential tissue-specific expression of the MUP gene family.

Identification of an enhancer required for the expression of a mouse major urinary protein gene in the submaxillary gland

The MUP1.5b gene was previously found to be expressed specifically in the submaxillary gland and at high levels when introduced into mice as a transgene including 4.7 kb of 5'-flanking DNA and 0.3 kb of 3'-flanking DNA. To localize regulatory elements responsible for this tissue-specific pattern of expression, we tested the expression of three additional MUP1.5b transgenes including various amounts of 5'-flanking DNA. These experiments indicated that sequences between -1.85 and -3.46 kb from the transcription initiation site were required for high-level expression in the submaxillary gland. The presence of regulatory elements in this region was also suggested by the detection of a DNase I-hypersensitive site, seen only in submaxillary gland nuclei, at position -2.5 kb upstream from the MUP1.5a gene, a member of the same MUP gene subfamily and virtually identical to the MUP1.5b gene. Further evidence for enhancer activity was provided by the ability of the 1.6-kb DNA fragment including sequences between -1.85 and -3.46 kb to stimulate the expression of an otherwise inactive MUP1.5b-chloramphenicol acetyltransferase fusion gene specifically in the submaxillary gland. The nucleotide sequence of this 1.6-kb DNA fragment was found to be identical for the MUP1.5a and MUP1.5b genes. Together, these results provide the first localization of a cis-acting regulatory sequence involved in the differential tissue-specific expression of the MUP gene family.