Myristic acid specifically stabilizes diacylglycerol kinase δ protein in C2C12 skeletal muscle cells

Kai Iwata, Hiromichi Sakai, Daisuke Takahashi, Fumio Sakane

研究成果: ジャーナルへの寄稿記事

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抄録

Decreased levels of the δ isozyme of diacylglycerol kinase (DGK) in skeletal muscle attenuate glucose uptake and, consequently, are critical for the pathogenesis of type 2 diabetes. We recently found that free myristic acid (14:0), but not free palmitic acid (16:0), increased the DGKδ protein levels and enhanced glucose uptake in C2C12 myotube cells. However, it has been unclear how myristic acid regulates the level of DGKδ2 protein. In the present study, we characterized the myristic acid-dependent increase of DGKδ protein. A cycloheximide chase assay demonstrated that myristic acid, but not palmitic acid, markedly stabilized DGKδ protein. Moreover, other DGK isozymes, DGKη and ζ, as well as glucose uptake-related proteins, such as protein kinase C (PKC) α, PKCζ, Akt and glycogen synthase kinase 3β, failed to be stabilized by myristic acid. Furthermore, DGKδ was not stabilized in cultured hepatocellular carcinoma cells, pancreas carcinoma cells or neuroblastoma cells, and only a moderate stabilizing effect was observed in embryonic kidney cells. A proteasome inhibitor and a lysosome inhibitor, MG132 and chloroquine, respectively, partly inhibited DGKδ degradation, suggesting that myristic acid prevents, at least in part, the degradation of DGKδ by the ubiquitin-proteasome system and the autophagy-lysosome pathway. Overall, these results strongly suggest that myristic acid attenuates DGKδ protein degradation in skeletal muscle cells and that this attenuation is fatty acid-, protein- and cell line-specific. These new findings provide novel insights into the molecular mechanisms of the pathogenesis of type 2 diabetes mellitus.

元の言語英語
ページ(範囲)1031-1038
ページ数8
ジャーナルBiochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
1864
発行部数7
DOI
出版物ステータス出版済み - 7 1 2019

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Diacylglycerol Kinase
Myristic Acid
Muscle Cells
Skeletal Muscle
Proteins
Palmitic Acid
Lysosomes
Glucose
Type 2 Diabetes Mellitus
Isoenzymes
Glycogen Synthase Kinase 3
Proteasome Inhibitors
Skeletal Muscle Fibers
Autophagy
Chloroquine
Proteasome Endopeptidase Complex
Cycloheximide
Ubiquitin
Neuroblastoma
Protein Kinase C

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Cell Biology

これを引用

Myristic acid specifically stabilizes diacylglycerol kinase δ protein in C2C12 skeletal muscle cells. / Iwata, Kai; Sakai, Hiromichi; Takahashi, Daisuke; Sakane, Fumio.

:: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids, 巻 1864, 番号 7, 01.07.2019, p. 1031-1038.

研究成果: ジャーナルへの寄稿記事

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abstract = "Decreased levels of the δ isozyme of diacylglycerol kinase (DGK) in skeletal muscle attenuate glucose uptake and, consequently, are critical for the pathogenesis of type 2 diabetes. We recently found that free myristic acid (14:0), but not free palmitic acid (16:0), increased the DGKδ protein levels and enhanced glucose uptake in C2C12 myotube cells. However, it has been unclear how myristic acid regulates the level of DGKδ2 protein. In the present study, we characterized the myristic acid-dependent increase of DGKδ protein. A cycloheximide chase assay demonstrated that myristic acid, but not palmitic acid, markedly stabilized DGKδ protein. Moreover, other DGK isozymes, DGKη and ζ, as well as glucose uptake-related proteins, such as protein kinase C (PKC) α, PKCζ, Akt and glycogen synthase kinase 3β, failed to be stabilized by myristic acid. Furthermore, DGKδ was not stabilized in cultured hepatocellular carcinoma cells, pancreas carcinoma cells or neuroblastoma cells, and only a moderate stabilizing effect was observed in embryonic kidney cells. A proteasome inhibitor and a lysosome inhibitor, MG132 and chloroquine, respectively, partly inhibited DGKδ degradation, suggesting that myristic acid prevents, at least in part, the degradation of DGKδ by the ubiquitin-proteasome system and the autophagy-lysosome pathway. Overall, these results strongly suggest that myristic acid attenuates DGKδ protein degradation in skeletal muscle cells and that this attenuation is fatty acid-, protein- and cell line-specific. These new findings provide novel insights into the molecular mechanisms of the pathogenesis of type 2 diabetes mellitus.",
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