A region on mouse distal chromosome 1 (Chr. 1) that is highly enriched in quantitative trait loci (QTLs) controlling neural and behavioral phenotypes overlaps with the peak region of a major obesity ...QTL (Nob3.38), which we identified in an intercross of New Zealand Obese (NZO) mice with C57BL/6J (B6). By positional cloning we recently identified a microdeletion within this locus causing the disruption of Ifi202b that protects from adiposity by suppressing expression of 11β-Hsd1. Here we show that the Nob3.38 segment also corresponds with the QTL rich region (Qrr1) on Chr. 1 and associates with increased voluntary running wheel activity, Rota-rod performance, decreased grip strength, and anxiety-related traits. The characterization of a subcongenic line carrying 14.2 Mbp of Nob3.38 with a polymorphic region of 4.4 Mbp indicates that the microdeletion and/or other polymorphisms in its proximity alter body weight, voluntary activity, and exploration. Since 27 out of 32 QTL were identified in crosses with B6, we hypothesized that the microdeletion and or adjacent SNPs are unique for B6 mice and responsible for some of the complex Qrr1-mediated effects. Indeed, a phylogenic study of 28 mouse strains revealed a NZO-like genotype for 22 and a B6-like genotype for NZW/LacJ and 4 other C57BL strains. Thus, we suggest that a Nob3.38 interval (173.0-177.4 Mbp) does not only modify adiposity but also neurobehavioral traits by a haplotype segregating with C57BL strains.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The GTPase ADP-ribosylation factor related protein 1 (ARFRP1) controls the recruitment of proteins such as golgin-245 to the
trans-Golgi. ARFRP1 is highly expressed in adipose tissues in which the ...insulin-sensitive glucose transporter GLUT4 is processed through the Golgi to a specialized endosomal compartment, the insulin-responsive storage compartment from which it is translocated to the plasma membrane in response to a stimulation of cells by insulin. In order to examine the role of ARFRP1 for GLUT4 targeting, subcellular distribution of GLUT4 was investigated in adipose tissue specific
Arfrp1 knockout (
Arfrp1
ad
−/−) mice. Immunohistochemical and ultrastructural studies of brown adipocytes demonstrated an abnormal
trans-Golgi in
Arfrp1
ad
−/− adipocytes. In addition, in
Arfrp1
ad
−/− adipocytes GLUT4 protein accumulated at the plasma membrane rather than being sequestered in an intracellular compartment. A similar missorting of GLUT4 was produced by siRNA-mediated knockdown of
Arfrp1 in 3T3-L1 adipocytes which was associated with significantly elevated uptake of deoxyglucose under basal conditions. Thus,
Arfrp1 appears to be involved in sorting of GLUT4.
1 Department of Pharmacology, German Institute of Human Nutrition Potsdam-Rehbrücke, Nuthetal
2 Institute for Zoo and Wildlife Research, Berlin, Germany
3 Obesity Research Center, Department of ...Psychiatry, University of Cincinnati, Cincinnati, Ohio
Among polygenic mouse models of obesity, the New Zealand obese (NZO) mouse exhibits the most severe phenotype, with fat depots exceeding 40% of total body weight at the age of 6 mo. Here we dissected the components of energy balance including feeding behavior, locomotor activity, energy expenditure, and thermogenesis compared with the related lean New Zealand black (NZB) and obese B6.V-Lep ob /J (ob/ob) strains (11% and 65% fat at 23 wk, respectively). NZO mice exhibited a significant hyperphagia that, when food intake was expressed per metabolic body mass, was less pronounced than that of the ob/ob strain. Compared with NZB, NZO mice exhibited increased meal frequency, meal duration, and meal size. Body temperature as determined by telemetry with implanted sensors was reduced in NZO mice, but again to a lesser extent than in the ob/ob strain. In striking contrast to ob/ob mice, NZO mice were able to maintain a constant body temperature during a 20-h cold exposure, thus exhibiting a functioning cold-induced thermogenesis. No significant differences in spontaneous home cage activity were observed among NZO, NZB, and ob/ob strains. When mice had access to voluntary running wheels, however, running activity was significantly lower in NZO than NZB mice and even lower in ob/ob mice. These data indicate that obesity in NZO mice, just as in humans, is due to a combination of hyperphagia, reduced energy expenditure, and insufficient physical activity. Because NZO mice differ strikingly from the ob/ob strain in their resistance to cold stress, we suggest that the molecular defects causing hyperphagia in NZO mice are located distal from leptin and its receptor.
feeding behavior; polygenic obesity; ob/ob mice; thermogenesis; locomotor activity
Expression of cytochromes P450 (CYP) is markedly reduced during inflammatory processes. In vitro studies with hepatocytes have shown that cytokines generated during these processes down-regulate CYP. ...However, it is not clear to what extent each individual cytokine contributes to the overall reduced expression of the various CYP isoenzymes in vivo. Interleukin 6 (IL-6), a major player during inflammatory processes, is recognized as the most important cytokine modulating the hepatic expression of acute-phase protein (APP) genes. For this reason, we selected the IL-6−/− mouse as a model to investigate the role of IL-6 in the down-regulation of hepatic CYP during experimental inflammation. Our results show that the reduction in messenger RNA (mRNA) levels of CYP1A2, CYP2A5, and CYP3A11 during turpentine-induced inflammation was abrogated in IL-6–deficient mice, confirming that IL-6 is an indispensable player for the down-regulation of hepatic CYP during aseptic inflammation. Moreover, the different CYP isoenzymes showed a variable grade of dependence on IL-6, CYP2A5 being the most sensitive one. In the case of CYP2E1, differences between IL-6−/− and wild-type mice were no longer maintained after 24 hours, suggesting a delayed, rather than abrogated, CYP down-regulation in the absence of IL-6. As opposed to that, hepatic CYP repression took place in IL-6–deficient mice during lipopolysaccharide (LPS)-mediated inflammation. This contrasting behavior observed for CYP is surprisingly similar to the one seen for extracellular (serum amyloid A, β-fibrinogen) and intracellular (metallothionein-1) APPs and points to the fact that, in the model of bacterial inflammation (LPS), the effects of IL-6 on CYP down-regulation are likely to be substituted by other cytokines or mediators.
(Hepatology 2000;32:49-55.)
1 Department of Pharmacology, German Institute of Human Nutrition Potsdam-Rehbruecke, Nuthetal
2 Max Delbrück Centre for Molecular Medicine, Berlin-Buch, Berlin, Germany
New Zealand obese (NZO) mice ...present a metabolic syndrome of obesity, insulin resistance, and diabetes. To identify chromosomal segments associated with these traits, we intercrossed NZO mice with the lean and diabetes-resistant C57BL/6J (B6) strain. Obesity and hyperglycemia in the (NZO x B6)F2 intercross population were predominantly due to a broad quantitative trait locus (QTL) on chromosome 1 ( Nob3 ; logarithm of the odds score 16.1, 16.0, 4.0 for body weight, body fat, and blood glucose, respectively), producing a difference between genotypes of 12.7 or 5.2 g of body weight and 12.0 or 4.0 g of body fat in females or males, respectively. In addition, significant QTL on chromosomes 3 and 13 and suggestive QTL on chromosomes 4, 6, 9, 12, 14, and 19 contributed to the obese phenotype. Distal chromosome 5 was significantly linked with plasma cholesterol (LOD score 10.7). Introgression of two segments of Nob3 into B6 confirmed the adipogenic effect of the QTL and suggested the presence of at least one causal gene. Haplotype mapping reduced the critical region of the distal part of the QTL to 31 Mbp containing the potential candidates Nr1i3 , Apoa2 , Atp1a2 , Prox1 , and Hsd11b1 . We conclude that obesity and hyperglycemia of NZO is to a large part caused by variant genes located in Nob3 on chromosome 1. Since these exert robust effects on a B6 background, the QTL Nob3 is a prime target for identification of a novel diabesity gene.
positional cloning; metabolic syndrome; diabetes; cholesterol; New Zealand obese mouse
Perivascular adipose tissue secretes an adipocyte-derived relaxing factor(s) (ADRF) that opens K(v) channels in rat arteries. Visceral fat accumulation causes adipocyte dysfunction, including ...hyposecretion of adiponectin. We tested the hypothesis that ADRF might be adiponectin and that adiponectin plays a role in the paracrine control of vascular tone by perivascular adipose tissue.
We studied Sprague-Dawley rats, wild-type and adiponectin gene-deficient (Apn 1-/-) mice, and New Zealand obese (NZO) mice. In rat aortas, recombinant adiponectin at serum levels (2-5 microg/ml) inhibited serotonin-induced contractions. The effects were abolished by K(v) channel inhibition with 4-aminopyridine (4-AP, 2 mM). Similar effects were observed in NZO mouse mesenteric arteries. To study vascular function in Apn 1-/- mice, the mesenteric vascular bed was isolated, cannulated, and perfused at a constant 4-5-ml/min flow in the absence and presence of serotonin. 4-AP (2 mM) induced a similar increase in perfusion pressure in the Apn 1-/- perfused isolated mesenteric vascular bed, compared to wild-type mice. Removal of perivascular fat increased the vasoconstrictor responses, but abolished the 4-AP effects. The anti-contractile effects of perivascular fat were similar in mesenteric artery and aortic rings from Apn 1-/- and wild-type mice. Despite high adiponectin levels, the anti-contractile effects of perivascular fat were diminished in mesenteric arteries of NZO mice with age.
Adiponectin is a novel humoral vasodilator that relaxes aortic and mesenteric rings by opening K(v) channels. Similar to the rat, perivascular adipose tissue of the mouse harbors an ADRF, which is malfunctional in NZO mice and is not adiponectin.
Background: Metabolic syndrome (MetS), a complex cluster of risk factors for chronic diseases such as cardiovascular disease, is observed to be increasingly associated with periodontal disease. ...However, the fundamental contribution of periodontal bacteria to periodontal bone loss in patients with MetS remains unclear. The aim of the present study is to analyze the effect of Porphyromonas gingivalis on differentiation of primary osteoblasts from New Zealand obese (NZO) mice, a model for MetS, compared with C57 Black 6 JAX (C57BL/6J) mice osteoblasts.
Methods: Primary calvarial osteoblasts, isolated from 3‐day‐old NZO and control C57BL/6J mice, were stimulated with P. gingivalis. Proliferation was quantified by 5‐bromo‐2′‐deoxyuridine incorporation. Cell cycle and early and late apoptosis were measured by flow cytometry. Gene expression was determined by real‐time polymerase chain reaction (RT‐PCR).
Results: Twelve hours after P. gingivalis stimulation, NZO osteoblasts showed significantly decreased proliferation (P ≤0.01) with increased G2 cell cycle phase compared with normal osteoblasts. Flow cytometry analysis demonstrated significant (P ≤0.01) increase of early apoptotic cells (annexin V positive) and late apoptosis (caspase 3 activity) in NZO cells compared with control cells at 3 and 6 hours after stimulation. No significant lactate dehydrogenase release was found after P. gingivalis stimulation. RT‐PCR data showed significantly suppressed expression (P ≤0.01) of collagen 1, osteocalcin, and Runt‐related transcription factor 2 in NZO cells compared with normal osteoblasts.
Conclusions: The present data demonstrate that P. gingivalis downregulates proliferation and promotes apoptosis in primary NZO osteoblasts, unlike C57BL/6J osteoblasts. Also, suppressed osteoblastic marker expression in NZO cells may contribute to pathogenesis of periodontitis, suggesting a similar process in patients with MetS.
Nob3 is a major obesity quantitative trait locus (QTL) identified in an intercross of New Zealand Obese (NZO) mice with C57BL/6J (B6), and by introgression of its 38 Mbp peak region into B6 ...(B6.NZO-Nob3.38). B6.NZO-Nob3.38 mice carrying the NZO allele exhibited markedly increased body weight, fat mass, lean mass and a lower energy expenditure, than the corresponding B6 allele carriers. For positional cloning of the responsible obesity gene, five additional congenic lines (RCS) were generated and characterized, allowing to define a critical genomic interval comprising 43 genes. mRNA profiling and western blotting indicated that Ifi202b, a member of the Ifi200 family of interferon inducible transcriptional modulators, was expressed in NZO-allele carriers but was undetectable in tissues of homozygous B6-allele carriers due to a microdeletion, including the first exon and the 5'-flanking region of Ifi202b in B6. Transcriptome analysis of adipose tissue of RCS revealed a marked induction of 11 beta -hydroxysteroid dehydrogenase type 1 (11 beta -Hsd1) expression in mice expressing Ifi202b. Furthermore, siRNA-mediated Ifi202b suppression in 3T3-L1 adipocytes resulted in a significant inhibition of 11 beta -Hsd1 expression, whereas an adenoviral-mediated overexpression of Ifi202b increased 11 beta -Hsd1 mRNA levels. Expression of human IFI orthologues was significantly increased in visceral adipose tissue of obese subjects. We suggest that the disruption of Ifi202b in B6 is responsible for the effects of the obesity QTL Nob3, and that Ifi202b modulates fat accumulation through expression of adipogenic genes such as 11 beta -Hsd1.
Genetic alterations can unpredictably compromise the wellbeing of animals. Thus, more or less harmful phenotypes might appear in the animals used in research projects even when they are not subjected ...to experimental treatments. The severity classification of suffering has become an important issue since the implementation of Directive 2010/63/EU on the protection of animals used for scientific purposes. Accordingly, the breeding and maintenance of genetically altered (GA) animals which are likely to develop a harmful phenotype has to be authorized. However, a determination of the degree of severity is rather challenging due to the large variety of phenotypes. Here, the Working Group of Berlin Animal Welfare Officers (WG Berlin AWO) provides field-tested guidelines on severity assessment and classification of GA rodents. With a focus on basic welfare assessment and severity classification we provide a list of symptoms that have been classified as non-harmful, mild, moderate or severe burdens. Corresponding monitoring and refinement strategies as well as specific housing requirements have been compiled and are strongly recommended to improve hitherto applied breeding procedures and conditions. The document serves as a guide to determine the degree of severity for an observed phenotype. The aim is to support scientists, animal care takers, animal welfare bodies and competent authorities with this task, and thereby make an important contribution to a European harmonization of severity assessments for the continually increasing number of GA rodents.
PDF
