A Limonoid, 7-Deacetoxy-7-Oxogedunin (CG-1) from Andiroba (Carapa guianensis, Meliaceae) Lowers the Accumulation of Intracellular Lipids in Adipocytes via Suppression of IRS-1/Akt-Mediated Glucose Uptake and a Decrease in GLUT4 Expression - PubMed (original) (raw)

A Limonoid, 7-Deacetoxy-7-Oxogedunin (CG-1) from Andiroba (Carapa guianensis, Meliaceae) Lowers the Accumulation of Intracellular Lipids in Adipocytes via Suppression of IRS-1/Akt-Mediated Glucose Uptake and a Decrease in GLUT4 Expression

Chihiro Matsumoto et al. Molecules. 2019.

Abstract

Limonoids are phytochemicals with a variety of biological properties. In the present study, we elucidated the molecular mechanism of suppression of adipogenesis in adipocytes by a limonoid, 7-deacetoxy-7-oxogedunin (CG-1) from Carapa guianensis (Meliaceae), known as andiroba. CG-1 reduced the accumulation of intracellular triglycerides in a concentration-dependent manner. The expression levels of the adipogenic, lipogenic, and lipolytic genes were decreased by CG-1 treatment, whereas the glycerol release level was not affected. When CG-1 was added into the medium during days 0-2 of 6-days-adipogenesis, the accumulation of intracellular lipids and the mRNA levels of the adipogenesis-related genes were decreased. In addition, the phosphorylation level of insulin receptor substrate-1 (IRS-1) and Akt in the early phase of adipocyte differentiation (within 1 day after initiating adipocyte differentiation) was reduced by CG-1. Furthermore, insulin-activated translocation of glucose transporter 4 to the plasma membranes in adipocytes was suppressed by CG-1, followed by decreased glucose uptake into the cells. These results indicate that an andiroba limonoid CG-1 suppressed the accumulation of intracellular lipids in the early phase of adipocyte differentiation through repression of IRS-1/Akt-mediated glucose uptake in adipocytes.

Keywords: GLUT4; IRS-1/Akt; adipocyte; andiroba; limonoid.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1

Figure 1

Purification of andiroba limonoid CG-1. (A) Chemical structure of the limonoid CG-1. (B) Chromatogram of CG-1 purified from the seeds of andiroba (C. guianensis, Meliaceae) by HPLC.

Figure 2

Figure 2

Suppression of intracellular lipid accumulation by CG-1. (A) Cytotoxicity of CG-1 in 3T3-L1 cells. The cells were incubated for 6 days in DMEM with various concentrations of CG-1 (0-10 μM). Data show the means ± S.D. from three experiments. (B) Oil Red O staining of intracellular lipid droplets. 3T3-L1 cells (undifferentiated cells: U) were differentiated into adipocytes (D) for 6 days in DMEM with various concentrations of CG-1 (0–10 μM). The cells were observed by a microscope (200x). Scale bar = 200 μm. (C) The intracellular triglyceride level. 3T3-L1 cells (undifferentiated cells: U; white column) were differentiated (D) into adipocytes for 6 days in DMEM without (gray column) or with CG-1 (0.5, 1, 5, 10 μM; black columns). Data are presented as the means ± S.D. from three experiments. * p < 0.01, ** p < 0.05, as indicated by the brackets.

Figure 3

Figure 3

Suppression of adipogenesis by CG-1 in 3T3-L1 cells. (A) Transcription levels of the adipogenesis-related genes in CG-1-treated 3T3-L1 cells. The cells (undifferentiated cells: U; white columns) were differentiated (D) into adipocytes for 6 days in DMEM without (gray columns) or with CG-1 (10 μM; black columns). Results are presented as the means ± S.D. from three experiments. * p < 0.01, ** p < 0.05, as indicated by the brackets. (B) Change in the protein levels in 3T3-L1 cells. The cells were cultured as described in the legend of Figure 3A. Protein (15 μg) was loaded in each lane. Data are representative of three experiments. β-actin was used as the internal control. γ1 and γ2 mean PPARγ isoforms: PPARγ1 and PPARγ2, respectively. Data are representative of three experiments. (C) Band intensity of Western blot analysis. About C/EBPα and GLUT4, both of these two bands were measured and shown as the total in band intensity. Results are presented as the means ± S.D. * p < 0.01, as indicated by the brackets. (D) Glycerol release level in 3T3-L1 cells. The cells were differentiated as described in the legend of Figure 3A. Data are the means ± S.D. from three experiments. * p < 0.01, as indicated by the bracket.

Figure 4

Figure 4

Adipocyte differentiation-phase-specific inhibition of adipogenesis by CG-1. (A) Addition of CG-1 into the medium at the indicated time-points in 6-days-adipogenesis. (B) Oil Red O staining of lipid droplets in phase-specific CG-1-treated 3T3-L1 cells. The cells (undifferentiated cells: U) were differentiated into adipocytes (differentiated cells: D) in DMEM with CG-1 (10 μM) during days 0–6, 0–2, 2–4, or 4–6 of 6-days-adipogenesis. Data are representative of three experiments. The cells were observed by a microscope (200×). Scale bar = 100 μm. (C) Intracellular triglyceride level in 3T3-L1 cells. The cells (undifferentiated cells: U; white column) were differentiated into adipocytes (differentiated cells: D) in DMEM without (gray column) or with CG-1 (10 μM; black columns) during days 0–6, 0–2, 2–4, or 4–6 of 6-days-adipogenesis. Results are shown as the means ± S.D. from three experiments. * p < 0.01, as indicated by the brackets. (D) Suppression of adipogenesis-related gene expression in the early phase of adipogenesis. Expression level of the adipogenic genes in CG-1-treated 3T3-L1 cells. The cells (undifferentiated cells: U; white columns) were differentiated (D) into adipocytes in DMEM without (gray columns) or with CG-1 (10 μM; black columns) during days 0–6, 0–2, 2–4, or 4–6 of 6-days-adipogenesis. Results are expressed as the means ± S.D. from three experiments. * p < 0.01, as indicated by the brackets.

Figure 5

Figure 5

Inhibition of activation of IRS-1/Akt axis by CG-1. (A) Expression and phosphorylation of IRS-1, and Akt in CG-1-treated 3T3-L1 cells. The cells were differentiated into adipocytes for the indicated time in DMEM with CG-1 (0 or 10 μM). Proteins (15 μg/lane) were subjected to SDS-PAGE-Western blot analysis. Data are representative of three experiments. (B) Band intensity of Western blot analysis. Results are presented as the means ± S.D. * p < 0.01, as indicated by the brackets.

Figure 6

Figure 6

Suppression of GLUT4 translocation and glucose uptake in CG-1-treated 3T3-L1 cells. (A) GLUT4 protein in the membrane- and total-fractions. 3T3-L1 cells were serum starved for 16 h and cultured in DMEM with insulin (10 μg/mL) and/or CG-1 (10 μM) for 10 min after pre-treatment with CG-1 (10 μM) for 1 h. The membrane fractions (membrane) were used for Western blot analysis. Total GLUT4 (total) was detected as the input control. Protein (10 μg) was loaded in each lane. Data are representative of three experiments. Band intensity was measured and calculated by MultiGauge software. * p < 0.01 or ** p < 0.05, as indicated by the brackets. (B) Glucose uptake in 3T3-L1 cells. The cells (undifferentiated cells: U; white columns) were differentiated into adipocytes (differentiated cells: D) for 1 or 6 day in DMEM without (gray columns) or with CG-1 (10 μM; black columns). 2-NBDG uptake level was measured by a fluorescent microplate reader. Results are the means ± S.D. from three experiments. p < 0.01, as indicated by the bracket.

Figure 7

Figure 7

Schematic representation of CG-1-mediated suppression of intracellular lipid accumulation in 3T3-L1 adipocytes.

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References

    1. Finucane M.M., Stevens G.A., Cowan M.J., Danaei G., Lin J.K., Paciorek C.J., Singh G.M., Gutierrez H.R., Lu Y., Bahalim A.N., et al. National, regional, and global trends in body-mass index since 1980: Systematic analysis of health examination surveys and epidemiological studies with 960 country-years and 9.1 million participants. Lancet. 2011;377:557–567. doi: 10.1016/S0140-6736(10)62037-5. - DOI - PMC - PubMed
    1. Attie A.D., Scherer P.E. Adipocyte metabolism and obesity. J. Lipid Res. 2009;50:S395–S399. doi: 10.1194/jlr.R800057-JLR200. - DOI - PMC - PubMed
    1. Cornier M.A., Dabelea D., Hernandez T.L., Lindstrom R.C., Steig A.J., Stob N.R., Van Pelt R.E., Wang H., Eckel R.H. The metabolic syndrome. Endocr. Rev. 2008;29:777–822. doi: 10.1210/er.2008-0024. - DOI - PMC - PubMed
    1. Ali A.T., Hochfeld W.E., Myburgh R., Pepper M.S. Adipocyte and adipogenesis. Eur. J. Cell Biol. 2013;92:229–236. doi: 10.1016/j.ejcb.2013.06.001. - DOI - PubMed
    1. Lefterova M.I., Lazar M.A. New developments in adipogenesis. Trends Endocrinol. Metab. 2009;20:107–114. doi: 10.1016/j.tem.2008.11.005. - DOI - PubMed

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