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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The agouti-related protein gene (Agrp) is a novel gene implicated in the control of feeding behavior. The hypothalamic expression of Agrp is regulated by leptin, and overexpression of Agrp in transgenic animals results in obesity and diabetes. By analogy with the known actions of agouti, these data suggest a role for the Agrp gene product in the regulation of melanocortin receptors expressed in the central nervous system. The availability of recombinant, highly purified protein is required to fully address this potential interaction. A nearly full-length form of AGRP (MKd5-AGRP) was expressed in the cytosolic or soluble fraction of Escherichia coli and appeared as large intermolecular disulfide-bonded aggregates. Following oxidation, refolding, and purification, this protein was soluble, and eluted as a single symmetric peak on RP-HPLC. Circular dichroism studies indicated that the purified protein contains primarily random coil and beta-sheet secondary structure. Sedimentation velocity studies at neutral pH demonstrated that MKd5-AGRP is monomeric at low micromolar concentrations. Mobility shifts observed using SDS-PAGE under reducing and nonreducing conditions for bacterially expressed and mammalian expressed AGRP were identical, an indication of a similar disulfide structure. The purification to homogeneity of a second, truncated form of AGRP (Md65-AGRP) which was expressed in the insoluble or inclusion body fraction is also described. Both forms act as competitive antagonists of alpha-melanocyte stimulating hormone (alpha-MSH) at melanocortin-3 (MC-3) and melanocortin-4 receptors (MC-4). The demonstration that AGRP is an endogenous antagonist with respect to these receptors is a unique mechanism within the central nervous system, and has important implications in the control of feeding.
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PMID:Biochemical, biophysical, and pharmacological characterization of bacterially expressed human agouti-related protein. 981 97

The mouse tubby phenotype is characterized by maturity-onset obesity accompanied by retinal and cochlear degeneration. A positional cloning effort to find the gene responsible for this phenotype led to the identification of tub, a member of a novel gene family of unknown function. A splice defect mutation in the 3' end of the tub gene, predicted to disrupt the C terminus of the Tub protein, has been implicated in the genesis of the tubby phenotype. It is not clear, however, whether the Tub mutant protein retains any biological activity, or perhaps has some dominant function, nor is it established that the tubby mutation is itself responsible for all of the observed tubby phenotypes. To address these questions, we generated tub-deficient mice and compared their phenotype to that of tubby mice. Our results demonstrate that tubby is a loss-of-function mutation of the tub gene and that loss of the tub gene is sufficient to give rise to the full spectrum of tubby phenotypes. We also demonstrate that loss of photoreceptors in the retina of tubby and tub-deficient mice occurs by apoptosis. In addition, we show that Tub protein expression is not significantly altered in the ob, db, or melanocortin 4 receptor-deficient mouse model of obesity.
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PMID:Targeted deletion of the tub mouse obesity gene reveals that tubby is a loss-of-function mutation. 1062 44

The hypothalamus plays a major role in the control of energy balance via the coordination of several neuropeptides and their receptors. We used a unique polygenic animal model of obesity, Psammomys obesus, and performed differential display polymerase chain reaction on hypothalamic mRNA samples to identify novel genes involved in obesity. In this study, we describe a novel gene that encodes a small protein we have termed "beacon." Beacon mRNA gene expression in the hypothalamus was positively correlated with percentage of body fat. Intracerebroventricular infusion of beacon resulted in a dose-dependent increase in food intake and body weight and an increase in hypothalamic expression of neuropeptide Y (NPY). Simultaneous infusion of beacon and NPY significantly potentiated the orexigenic response and resulted in rapid body weight gain. These data suggest a role for beacon in the regulation of energy balance and body weight homeostasis that may be mediated, at least in part, through the NPY pathway.
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PMID:Beacon: a novel gene involved in the regulation of energy balance. 1107 42

Obese gene (ob) is a novel gene cloned recently. The product of ob gene Leptin is an important signal reflecting body fat mass and controlling body weight. In this study the complete nucleotide sequences of porcine ob cDNA were identified, and the homology with ob genes from other species was also compared. The porcine fat cDNA was constructed based on lambda Uni-ZAP system. The primers designed on the consensus region of human and mouse ob gene were employed to perform PCR-screening of the cDNA library, and a 366 bp DNA fragment amplified from total RNA of pig fat cells was used to confirm positives as a hybridization probe. The complete ob cDNA with 3277 bp in length was cloned and sequenced. The nucleotide sequences of ob genes between different species were very conservative. The overall identity of ob nucleotide sequences was 88.5% between pig and human, 84.7% between pig and mouse. The homology of ob amino acid sequences was 86.0% between pig and human. 83.4% between pig and mouse. The result of RT-PCR for transcripts detection of pig ob gene indicate that ob gene was expressed not only mainly in adipose tissue but also slightly in other tissues such as kidney, liver, spleen, heart and muscle, which imply that expression nature of pig ob gene is different from that of human and mouse ob gene.
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PMID:[Molecular cloning and analysing of porcine obese cDNA]. 1114 46

Bardet-Biedl syndrome (BBS) is a genetically heterogeneous autosomal recessive disorder with the primary clinical features of obesity, pigmented retinopathy, polydactyly, hypogenitalism, mental retardation and renal anomalies. Associated features of the disorder include diabetes mellitus, hypertension and congenital heart disease. There are six known BBS loci, mapping to chromosomes 2, 3, 11, 15, 16 and 20. The BBS2 locus was initially mapped to an 18 cM interval on chromosome 16q21 with a large inbred Bedouin kindred. Further analysis of the Bedouin population allowed for the fine mapping of this locus to a 2 cM region distal to marker D16S408. Physical mapping and sequence analysis of this region resulted in the identification of a number of known genes and expressed sequence tag clusters. Mutation screening of a novel gene (BBS2) with a wide pattern of tissue expression revealed homozygous mutations in two inbred pedigrees, including the large Bedouin kindred used to initially identify the BBS2 locus. In addition, mutations were found in three of 18 unrelated BBS probands from small nuclear families.
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PMID:Positional cloning of a novel gene on chromosome 16q causing Bardet-Biedl syndrome (BBS2). 1128 52

Bardet-Biedl syndrome (BBS, MIM 209900) is a heterogeneous autosomal recessive disorder characterized by obesity, pigmentary retinopathy, polydactyly, renal malformations, mental retardation, and hypogenitalism. The disorder is also associated with diabetes mellitus, hypertension, and congenital heart disease. Six distinct BBS loci map to 11q13 (BBS1), 16q21 (BBS2), 3p13-p12 (BBS3), 15q22.3-q23 (BBS4), 2q31 (BBS5), and 20p12 (BBS6). Although BBS is rare in the general population (<1/100,000), there is considerable interest in identifying the genes causing BBS because components of the phenotype, such as obesity and diabetes, are common. We and others have demonstrated that BBS6 is caused by mutations in the gene MKKS (refs. 12,13), mutation of which also causes McKusick-Kaufman syndrome (hydrometrocolpos, post-axial polydactyly, and congenital heart defects). MKKS has sequence homology to the alpha subunit of a prokaryotic chaperonin in the thermosome Thermoplasma acidophilum. We recently identified a novel gene that causes BBS2. The BBS2 protein has no significant similarity to other chaperonins or known proteins. Here we report the positional cloning and identification of mutations in BBS patients in a novel gene designated BBS4.
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PMID:Identification of the gene that, when mutated, causes the human obesity syndrome BBS4. 1138 Dec 70

We have used a mRNA differential display technique to identify new genes involved in the reprogramming of gene expression during the adipose conversion of mouse 3T3 preadipocyte cell lines. We report here on the identification and cloning of a novel adipose-specific cDNA encoding a predicted membrane protein of 413 amino acids. The level of the corresponding 3.2-kilobase mRNA is tremendously increased during 3T3-L1 and 3T3-F442A differentiation into adipocytes. A single, very abundant 3.2-kilobase transcript is also found in inguinal and epididymal white adipose tissues and in interscapular brown adipose tissue but not in any other tissues examined. Its expression in adipose tissue is under tight nutritional regulation. The level of this novel 3.2-kilobase transcript becomes virtually nondetectable during fasting but is dramatically increased when fasted mice are refed a high carbohydrate diet. Based on its adipose specificity and dietary regulation, the novel gene product has been designated adiponutrin. The expression of adiponutrin mRNA is also 50-fold elevated in genetically obese fa/fa rats, indicating a link between adiponutrin and obesity. Western blot and confocal imagery analyses with epitope-tagged protein transiently expressed in 3T3-L1 adipocytes, and COS cells show that adiponutrin strictly localizes to membranes and is absent from the cytosol. Sequence analysis reveals homologies with several other members of related eukaryotic proteins, including a human paralog, which has been recently described in vesicular transport mechanisms. This leads us to suggest that adiponutrin could be involved in vesicular targeting and protein transport restricted to the adipocyte function.
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PMID:Adiponutrin, a transmembrane protein corresponding to a novel dietary- and obesity-linked mRNA specifically expressed in the adipose lineage. 1143 82

Plasmolipin is a membrane protein and belongs to the tetraspan molecule (4TM) family, an expanding group of myelin proteins many of which could be linked to human hereditary demyelinating neuropathies. We have cloned and sequenced the mouse plasmolipin gene, revealing the common organization of the 4TM gene group with four exons and a large first intron. Western blot analysis with an antibody raised against the C-terminal intracellular part of the protein showed that plasmolipin is expressed not only in the nervous system and kidney, but also in a number of other tissues such as thymus, testis, lung, and thyroid gland. By means of radiation hybrid mapping and FISH analysis, we could localize the human plasmolipin gene to Chromosome 16q13 within the putative region of the Bardet-Biedl syndrome type 2 (BBS2) gene locus. BBS2 is a clinically and genetically heterogeneous group of disorders resulting in rod-cone dystrophy, obesity, postaxial polydactyly, renal dysfunction, and mental retardation, which were very recently associated with a novel gene designated BBS2. With respect to intrafamiliar variations in the manifestation of BBS, we suggest that plasmolipin might be either another candidate gene or a modifier of the BBS2 phenotype.
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PMID:Plasmolipin: genomic structure, chromosomal localization, protein expression pattern, and putative association with Bardet-Biedl syndrome. 1170 81

Morbid obesity is the result of massive expansion of white adipose tissue (WAT) and requires recruitment of adipocyte precursor cells and their supporting infrastructure. To characterize the change in the expression profile of the preexisting WAT at the start of obesity, when adipocyte hypertrophy is present but hyperplasia is still minimal, we employed a cDNA subtraction screen for genes differentially expressed in epididymal fat pads harvested 1 wk after the start of a 60% fat diet. Ninety-six genes were upregulated by at least 50% above the WAT of control rats receiving a 4% fat diet. Of these genes, 30 had not previously been identified. Sixteen of the 96 genes, including leptin, adipocyte complement-related protein 30 kDa, and resistin, were predicted to encode a signal peptide. Ten of the 16 had been previously identified in other tissues and implicated in cell growth, proliferation, differentiation, cell cycle control, and angiogenesis. One was a novel gene. Twenty-nine novel fragments were identified. Thus, at the onset of high-fat-diet-induced obesity in rats, adipose tissue increases its expression of factors previously implicated in the expansion of nonadipocyte tissues and of several uncharacterized novel factors. The only one of these thus far characterized functionally was found to promote lipogenesis.
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PMID:Gene expression profile of rat adipose tissue at the onset of high-fat-diet obesity. 1200 64

DNA-based approaches to the discovery of genes contributing to the development of type 2 diabetes have not been very successful despite substantial investments of time and money. The multiple gene-gene and gene-environment interactions that influence the development of type 2 diabetes mean that DNA approaches are not the ideal tool for defining the etiology of this complex disease. Gene expression-based technologies may prove to be a more rewarding strategy to identify diabetes candidate genes. There are a number of RNA-based technologies available to identify genes that are differentially expressed in various tissues in type 2 diabetes. These include differential display polymerase chain reaction (ddPCR), suppression subtractive hybridization (SSH), and cDNA microarrays. The power of new technologies to detect differential gene expression is ideally suited to studies utilizing appropriate animal models of human disease. We have shown that the gene expression approach, in combination with an excellent animal model such as the Israeli sand rat (Psammomys obesus), can provide novel genes and pathways that may be important in the disease process and provide novel therapeutic approaches. This paper will describe a new gene discovery, beacon, a novel gene linked with energy intake. As the functional characterization of novel genes discovered in our laboratory using this approach continues, it is anticipated that we will soon be able to compile a definitive list of genes that are important in the development of obesity and type 2 diabetes.
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PMID:New approaches to gene discovery with animal models of obesity and diabetes. 1207 68


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