Similar articles

Abstract: It is widely accepted that body weight and adipose mass are tightly regulated by homeostatic mechanisms, in which leptin plays a critical role through hypothalamic pathways, and obesity is a result of homeostatic disorder. However, in C57BL/6J mice, we found that Rcan2 increases food intake and plays an important role in the development of age- and diet-induced obesity through a leptin-independent mechanism. RCAN2 was initially identified as a thyroid hormone (T3)-responsive gene in human fibroblasts. Expression of RCAN2 is regulated by T3 through the PI3K-Akt/PKB-mTOR-Rps6kb1 signaling pathway. Intriguingly, both Rcan2^−/− and Rps6kb1^−/− mutations were reported to result in lean phenotypes in mice. In this study we compared the effects of these two mutations on growth and body weight in C57BL/6J mice. We observed reduced body weight and lower fat mass in both Rcan2^−/− and Rps6kb1^−/− mice compared to the wild-type mice, and we reported other differences unique to either the Rcan2^−/− or Rps6kb1^−/− mice. Firstly, loss of Rcan2 does not directly alter body length; however, Rcan2^−/− mice exhibit reduced food intake. In contrast, Rps6kb1^−/− mice exhibit abnormal embryonic development, which leads to smaller body size and reduced food intake in adulthood. Secondly, when fed a normal chow diet, Rcan2^−/− mice weigh significantly more than Rps6kb1^−/− mice, but both Rcan2^−/− and Rps6kb1^−/− mice develop similar amounts of epididymal fat. On a high-fat diet, Rcan2^−/− mice gain body weight and fat mass at slower rates than Rps6kb1^−/− mice. Finally, using the double-knockout mice (Rcan2^−/− Rps6kb1^−/−), we demonstrate that concurrent loss of Rcan2 and Rps6kb1 has an additive effect on body weight reduction in C57BL/6J mice. Our data suggest that Rcan2 and Rps6kb1 mutations both affect growth and body weight of mice, though likely through different mechanisms.

肥胖研究中的一个争议性证据：Rcan2^−/−和Rps6kb1^−/−两种突变对C57BL/6J纯系小鼠的生长及体重影响的比较

[1]Baker, J., Liu, J.P., Robertson, E.J., et al., 1993. Role of insulin-like growth factors in embryonic and postnatal growth. Cell, 75(1):73-82.

[2]Bassett, J.H., Logan, J.G., Boyde, A., et al., 2012. Mice lacking the calcineurin inhibitor Rcan2 have an isolated defect of osteoblast function. Endocrinology, 153(7):3537-3548.

[3]Black, B.L., Croom, J., Eisen, E.J., et al., 1998. Differential effects of fat and sucrose on body composition in A/J and C57BL/6 mice. Metabolism, 47(11):1354-1359.

[4]Blouet, C., Ono, H., Schwartz, G.J., 2008. Mediobasal hypothalamic p70 S6 kinase 1 modulates the control of energy homeostasis. Cell Metab., 8(6):459-467.

[5]Bray, G.A., Popkin, B.M., 1998. Dietary fat intake does affect obesity! Am. J. Clin. Nutr., 68(6):1157-1173.

[6]Cao, X., Kambe, F., Moeller, L.C., et al., 2005. Thyroid hormone induces rapid activation of Akt/protein kinase B-mammalian target of rapamycin-p70S6K cascade through phosphatidylinositol 3-kinase in human fibroblasts. Mol. Endocrinol., 19(1):102-112.

[7]Cinti, S., Mitchell, G., Barbatelli, G., et al., 2005. Adipocyte death defines macrophage localization and function in adipose tissue of obese mice and humans. J. Lipid Res., 46(11):2347-2355.

[8]Cota, D., Proulx, K., Smith, K.A., et al., 2006. Hypothalamic mTOR signaling regulates food intake. Science, 312(5775):927-930.

[9]Cota, D., Matter, E.K., Woods, S.C., et al., 2008. The role of hypothalamic mammalian target of rapamycin complex 1 signaling in diet-induced obesity. J. Neurosci., 28(28):7202-7208.

[10]Dagon, Y., Hur, E., Zheng, B., et al., 2012. p70S6 kinase phosphorylates AMPK on serine 491 to mediate leptin’s effect on food intake. Cell Metab., 16(1):104-112.

[11]de Jonghe, B.C., Hayes, M.R., Bence, K.K., 2011. Melanocortin control of energy balance: evidence from rodent models. Cell. Mol. Life Sci., 68(15):2569-2588.

[12]Dufner, A., Thomas, G., 1999. Ribosomal S6 kinase signaling and the control of translation. Exp. Cell Res., 253(1):100-109.

[13]Eckel, R.H., Grundy, S.M., Zimmet, P.Z., 2005. The metabolic syndrome. Lancet, 365(9468):1415-1428.

[14]Eisen, E.J., Leatherwood, J.M., 1981. Predicting percent fat in mice. Growth, 45(2):100-107.

[15]Fingar, D.C., Salama, S., Tsou, C., et al., 2002. Mammalian cell size is controlled by mTOR and its downstream targets S6K1 and 4EBP1/eIF4E. Genes Dev., 16(12):1472-1487.

[16]Flier, J.S., 2004. Obesity wars: molecular progress confronts an expanding epidemic. Cell, 116(2):337-350.

[17]Fraulob, J.C., Ogg-Diamantino, R., Fernandes-Santos, C., et al., 2010. A mouse model of metabolic syndrome: insulin resistance, fatty liver and non-alcoholic fatty pancreas disease (NAFPD) in C57BL/6 mice fed a high fat diet. J. Clin. Biochem. Nutr., 46(3):212-223.

[18]Garfield, A.S., Lam, D.D., Marston, O.J., et al., 2009. Role of central melanocortin pathways in energy homeostasis. Trends Endocrinol. Metab., 20(5):203-215.

[19]Hill, J.O., Peters, J.C., 1998. Environmental contributions to the obesity epidemic. Science, 280(5368):1371-1374.

[20]Kahn, B.B., Flier, J.S., 2000. Obesity and insulin resistance. J. Clin. Invest., 106(4):473-481.

[21]Kappeler, L., de Magalhaes Filho, C., Leneuve, P., et al., 2009. Early postnatal nutrition determines somatotropic function in mice. Endocrinology, 150(1):314-323.

[22]Kawasome, H., Papst, P., Webb, S., et al., 1998. Targeted disruption of p70 (S6K) defines its role in protein synthesis and rapamycin sensitivity. PNAS, 95(9):5033-5038.

[23]Kolak, M., Westerbacka, J., Velagapudi, V.R., et al., 2007. Adipose tissue inflammation and increased ceramide content characterize subjects with high liver fat content independent of obesity. Diabetes, 56(8):1960-1968.

[24]Laplante, M., Sabatini, D.M., 2012. mTOR signaling in growth control and disease. Cell, 149(2):274-293.

[25]Lissner, L., Heitmann, B.L., 1995. Dietary fat and obesity: evidence from epidemiology. Eur. J. Clin. Nutr., 49(2):79-90.

[26]Ma, X.M., Blenis, J., 2009. Molecular mechanisms of mTOR-mediated translational control. Nat. Rev. Mol. Cell Biol., 10(5):307-318.

[27]Magnuson, B., Ekim, B., Fingar, D.C., 2012. Regulation and function of ribosomal protein S6 kinase (S6K) within mTOR signalling networks. Biochem. J., 441(1):1-21.

[28]Miyazaki, T., Kanou, Y., Murata, Y., et al., 1996. Molecular cloning of a novel thyroid hormone-responsive gene, ZAKI-4, in human skin fibroblasts. J. Biol. Chem., 271(24):14567-14571.

[29]Mizuno, Y., Kanou, Y., Rogatcheva, M., et al., 2004. Genomic organization of mouse ZAKI-4 gene that encodes ZAKI-4 α and β isoforms, endogenous calcineurin inhibitors, and changes in the expression of these isoforms by thyroid hormone in adult mouse brain and heart. Eur. J. Endocrinol., 150(3):371-380.

[30]Monteiro, R., de Castro, P.M., Calhau, C., et al., 2006. Adipocyte size and liability to cell death. Obes. Surg., 16(6):804-806.

[31]Mori, H., Inoki, K., Munzberg, H., et al., 2009. Critical role for hypothalamic mTOR activity in energy balance. Cell Metab., 9(4):362-374.

[32]Morton, G.J., Cummings, D.E., Baskin, D.G., et al., 2006. Central nervous system control of food intake and body weight. Nature, 443(7109):289-295.

[33]Ohanna, M., Sobering, A.K., Lapointe, T., et al., 2005. Atrophy of S6K1^−/− skeletal muscle cells reveals distinct mTOR effectors for cell cycle and size control. Nat. Cell Biol., 7(3):286-294.

[34]Reed, D.R., Lawler, M.P., Tordoff, M.G., 2008. Reduced body weight is a common effect of gene knockout in mice. BMC Genet., 9:4.

[35]Roa, J., Tena-Sempere, M., 2010. Energy balance and puberty onset: emerging role of central mTOR signaling. Trends Endocrinol. Metab., 21(9):519-528.

[36]Rogers, P., Webb, G.P., 1980. Estimation of body fat in normal and obese mice. Br. J. Nutr., 43(1):83-86.

[37]Schwartz, M.W., Porte, D.Jr., 2005. Diabetes, obesity, and the brain. Science, 307(5708):375-379.

[38]Shima, H., Pende, M., Chen, Y., et al., 1998. Disruption of the p70^s6k/p85^s6k gene reveals a small mouse phenotype and a new functional S6 kinase. EMBO J., 17(22):6649-6659.

[39]Smith, J., Al-Amri, M., Dorairaj, P., et al., 2006. The adipocyte life cycle hypothesis. Clin. Sci. (Lond.), 110(1):1-9.

[40]Smith, M.A., Katsouri, L., Irvine, E.E., et al., 2015. Ribosomal S6K1 in POMC and AgRP neurons regulates glucose homeostasis but not feeding behavior in mice. Cell Rep., 11(3):335-343.

[41]Strissel, K.J., Stancheva, Z., Miyoshi, H., et al., 2007. Adipocyte death, adipose tissue remodeling, and obesity complications. Diabetes, 56(12):2910-2918.

[42]Sun, X.Y., Hayashi, Y., Xu, S., et al., 2011. Inactivation of the Rcan2 gene in mice ameliorates the age- and diet-induced obesity by causing a reduction in food intake. PLOS ONE, 6(1):e14605.

[43]Surwit, R.S., Kuhn, C.M., Cochrane, C., et al., 1988. Diet-induced type II diabetes in C57BL/6J mice. Diabetes, 37(9):1163-1167.

[44]Surwit, R.S., Feinglos, M.N., Rodin, J., et al., 1995. Differential effects of fat and sucrose on the development of obesity and diabetes in C57BL/6J and A/J mice. Metabolism, 44(5):645-651.

[45]Um, S.H., Frigerio, F., Watanabe, M., et al., 2004. Absence of S6K1 protects against age- and diet-induced obesity while enhancing insulin sensitivity. Nature, 431(7005):200-205.

[46]Um, S.H., Sticker-Jantscheff, M., Chau, G.C., et al., 2015. S6K1 controls pancreatic β cell size independently of intrauterine growth restriction. J. Clin. Invest., 125(7):2736-2747.

[47]van der Klaauw, A.A., Farooqi, I.S., 2015. The hunger genes: pathways to obesity. Cell, 161(1):119-132.

[48]Wade, G.N., 1972. Gonadal hormones and behavioral regulation of body weight. Physiol. Behav., 8(3):523-534.

[49]Weisberg, S.P., McCann, D., Desai, M., et al., 2003. Obesity is associated with macrophage accumulation in adipose tissue. J. Clin. Invest., 112(12):1796-1808.

[50]Zimmet, P., Alberti, K.G., Shaw, J., 2001. Global and societal implications of the diabetes epidemic. Nature, 414(6865):782-787.

[51]List of electronic supplementary materials

[52]Table S1 Individual mouse data on NCD

[53]Table S2 Individual mouse data on HFD

[54]Table S3 Individual mouse data for pair-feeding

[55]Table S4 Individual mouse data for double-mutants