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, 8 (1), 17001

Endogenous Calcitonin Regulates Lipid and Glucose Metabolism in Diet-Induced Obesity Mice

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Endogenous Calcitonin Regulates Lipid and Glucose Metabolism in Diet-Induced Obesity Mice

Misa Nakamura et al. Sci Rep.

Abstract

Calcitonin (CT) plays an important role in calcium homeostasis, and its precursor, proCT, is positively associated with the body mass index in the general human population. However, the physiological role of endogenous CT in the regulation of metabolism remains unclear. Knockout mice with gene-targeted deletion of exon 4 of Calca (CT KO) were generated by targeted modification in embryonic stem cells. Male mice were used in all experiments and were fed a slightly higher fat diet than the standard diet. The CT KO mice did not exhibit any abnormal findings in appearance, but exhibited weight loss from 15 months old, i.e., significantly decreased liver, adipose tissue, and kidney weights, compared with wild-type control mice. Furthermore, CT KO mice exhibited significantly decreased fat contents in the liver, lipid droplets in adipose tissues, serum glucose, and lipid levels, and significantly increased insulin sensitivity and serum adiponectin levels. CT significantly promoted 3T3-L1 adipocyte differentiation and suppressed adiponectin release. These results suggested that CT gene deletion prevents obesity, hyperglycemia, and hyperlipidemia in aged male mice. This is the first definitive evidence that CT may contribute to glucose and lipid metabolism in aged male mice, possibly via decreased adiponectin secretion from adipocytes.

Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
Production of CT KO mice. (A) Schematic representation of Calca tissue-specific alternative RNA processing and precursor peptide processing. CCP-I; CT carboxyl-terminus peptide-I. (B) Schematic of recombination of the targeting vector with Calca. Black bars indicate the general location of DNA probes used for Southern blotting. EX; exon, Neor; neomycin resistance, tk; thymidine kinase. (C) Representative Southern blot analysis of SpeI or PvuII-digested DNA isolated from neomycin-resistant embryonic stem cells showing targeted (T) and untargeted (U) clones. A restriction map outlining the origin of individual bands is provided in B. (D) Identification of mouse genotype by PCR analysis of tail-derived DNA (see Methods). PCR products in +/+ show the presence of the normal WT allele; −/− shows the rearranged KO allele. Both alleles are detected in heterozygous animals (+/−). MW, 100-bp ladder molecular weight marker. E, RT-PCR analysis of mRNA isolated from the thyroid glands of WT or KO animals (see Methods). Primer pairs were exon 3F and exon 4R for detecting mRNAs for CT, exon 3F and exon 6 R for αCGRP, and β-actinF and β-actinR for β-actin.
Figure 2
Figure 2
External appearances and body weights of WT and KO mice. (A) External appearances of WT and KO mice at 19 months of age. (B) Body weights of WT and KO mice at 3, 6, 10, 15, and 19 months of age (n = 8–17/group). WT body weight and KO body weight at each age were compared with the Student’s t test. *p < 0.05, **p < 0.01, vs. WT group.
Figure 3
Figure 3
KO mice tended to show resistance to fatty liver. (A) The weights of organs at 19 months of age (n = 16–17/group). WT fat weight and KO fat weight were compared with the Welch’s t test. The weights of liver, pancreas, spleen, and kidney between WT and KO were compared with the Student’s t test. *p < 0.05, **p < 0.01 vs. WT group. (B) Hematoxylin and eosin staining of liver (a,g), intra-abdominal WAT (b,h), interscapular BAT (c,i), and islets (d,j) of WT (a–d) and KO (g–j) mice at 19 months of age. Immunostaining for β-cells (insulin staining) (e,k), and α-cells (glucagon staining) (f,l) of WT (a–f) and KO (g,h) mice at 19 months old. Scale bar: 100 µm.
Figure 4
Figure 4
KO mice showed decreases in both serum and liver lipids. Serum triglyceride (A) serum NEFA (B) and serum total cholesterol (C) after 16 h of fasting at 14 months of age (n = 24–25/group). Liver triglyceride (D) liver free cholesterol (E) and liver total cholesterol (F) after 16 h of fasting at 17 months of age (n = 5/group). (A,C,D,F) were analyzed with the Student’s t test. B was analyzed with the Welch’s t test. E was analyzed with the Wilcoxon signed-rank test. *p < 0.05, **p < 0.01 vs. WT group.
Figure 5
Figure 5
Decreases in serum glucose levels in KO mice were related to insulin sensitivity. (A) Blood glucose levels following 16 h of fasting in 19-month-old WT (solid line) and KO (dashed line) mice (n = 6/group). (B) Serum insulin levels following 16 h of fasting in 14-month-old mice (n = 7–8/group). (C) Blood glucose levels during the insulin tolerance test in 17-month-old WT (solid line) and KO (dashed line) mice following 3 h of fasting (n = 7–8/group). All results were analyzed with the Student’s t test. *p < 0.05 vs. WT group.
Figure 6
Figure 6
Serum adiponectin levels were higher in KO mice. Serum TNF-α (A) and adiponectin (B) following 16 h of fasting in 14-month-old mice (n = 7–8/group). A was analyzed with Student’s t test. B was analyzed with the Wilcoxon signed-rank test. *p < 0.05 vs. WT group.
Figure 7
Figure 7
CT increased the lipid contents and decreased production of adiponectin in 3T3-L1 cells. (A) Lipid content in cells treated with different concentrations of CT during adipocyte differentiation for 4 days (n = 5/group). (B) Adiponectin levels in medium treated with different concentrations of CT during adipocyte differentiation for 4 days (n = 5/group). (C) Oil Red O staining of differentiated cells. Scale bar: 50 µm (top), 25 µm (bottom). (A,B) were analyzed with the Student’s t test. *p < 0.05, **p < 0.01, ***p < 0.0001 vs. control (0 M CT) group.

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References

    1. Zaidi M, et al. A quantitative description of components of in vitro morphometric change in the rat osteoclast model: relationships with cellular function. Eur. Biophys. J. 1992;21:349–355. doi: 10.1007/BF00188348. - DOI - PubMed
    1. Lalley PA, et al. Mapping polypeptide hormone genes in the mouse: somatostatin, glucagon, calcitonin, and parathyroid hormone. Cytogenet. Cell Genet. 1987;44:92–97. doi: 10.1159/000132350. - DOI - PubMed
    1. Rosenfeld MG, Amara SG, Roos BA, Ong ES, Evans RM. Altered expression of the calcitonin gene associated with RNA polymorphism. Nature. 1981;290:63–65. doi: 10.1038/290063a0. - DOI - PubMed
    1. Rehli M, Luger K, Beier W, Falk W. Molecular cloning and expression of mouse procalcitonin. Biochem. Biophys. Res. Commun. 1996;226:420–425. doi: 10.1006/bbrc.1996.1371. - DOI - PubMed
    1. Russwurm S, et al. Molecular aspects and natural source of procalcitonin. Clin. Chem. Lab. Med. 1999;37:789–797. doi: 10.1515/CCLM.1999.119. - DOI - PubMed

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