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Muscle-specific knock-out of NUAK family SNF1-like kinase 1 (NUAK1) prevents high fat diet-induced glucose intolerance.

Inazuka F, Sugiyama N, Tomita M, Abe T, Shioi G, Esumi H - J. Biol. Chem. (2012)

Bottom Line: Quantitative phosphoproteome analysis of soleus muscle was performed to understand the molecular mechanisms underlying the knock-out phenotype.Nuak1 mRNA was preferentially expressed in highly oxidative tissues such as brain, heart, and soleus muscle.Phosphoproteome analysis revealed that phosphorylation of IRS1 Ser-1097 was markedly decreased in NUAK1-deficient muscle.

View Article: PubMed Central - PubMed

Affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan.

ABSTRACT
NUAK1 is a member of the AMP-activated protein kinase-related kinase family. Recent studies have shown that NUAK1 is involved in cellular senescence and motility in epithelial cells and fibroblasts. However, the physiological roles of NUAK1 are poorly understood because of embryonic lethality in NUAK1 mice. The purpose of this study was to elucidate the roles of NUAK1 in adult tissues. We determined the tissue distribution of NUAK1 and generated muscle-specific NUAK1 knock-out (MNUAK1KO) mice. For phenotypic analysis, whole body glucose homeostasis and muscle glucose metabolism were examined. Quantitative phosphoproteome analysis of soleus muscle was performed to understand the molecular mechanisms underlying the knock-out phenotype. Nuak1 mRNA was preferentially expressed in highly oxidative tissues such as brain, heart, and soleus muscle. On a high fat diet, MNUAK1KO mice had a lower fasting blood glucose level, greater glucose tolerance, higher insulin sensitivity, and higher concentration of muscle glycogen than control mice. Phosphoproteome analysis revealed that phosphorylation of IRS1 Ser-1097 was markedly decreased in NUAK1-deficient muscle. Consistent with this, insulin signaling was enhanced in the soleus muscle of MNUAK1KO mice, as evidenced by increased phosphorylation of IRS1 Tyr-608, AKT Thr-308, and TBC1D4 Thr-649. These observations suggest that a physiological role of NUAK1 is to suppress glucose uptake through negative regulation of insulin signaling in oxidative muscle.

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MNUAK1KO mice display no morphological abnormalities.A and B, weight of heart (A) and soleus muscle (B) of control and MNUAK1KO mice fed a NC or HFD. The indicated values are normalized to body weight. The data are the means ± S.E. (n = 10). C, cross-section of soleus muscle myocytes stained with wheat germ agglutinin. Scale bars, 20 μm. The graph below shows the average myocyte cross-sectional area for control and MNUAK1KO mice. The data are the means ± S.E. (n = 6). D–F, real time RT-PCR analysis of PGC-1α (D), TNNC1 (E), and TNNC2 (F). The mRNA levels are expressed relative to that of the soleus in control mice. The data are the means ± S.E. (n = 3). Mice at the age of 13–15 weeks were used for all experiments. Sol, soleus.
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Figure 2: MNUAK1KO mice display no morphological abnormalities.A and B, weight of heart (A) and soleus muscle (B) of control and MNUAK1KO mice fed a NC or HFD. The indicated values are normalized to body weight. The data are the means ± S.E. (n = 10). C, cross-section of soleus muscle myocytes stained with wheat germ agglutinin. Scale bars, 20 μm. The graph below shows the average myocyte cross-sectional area for control and MNUAK1KO mice. The data are the means ± S.E. (n = 6). D–F, real time RT-PCR analysis of PGC-1α (D), TNNC1 (E), and TNNC2 (F). The mRNA levels are expressed relative to that of the soleus in control mice. The data are the means ± S.E. (n = 3). Mice at the age of 13–15 weeks were used for all experiments. Sol, soleus.

Mentions: For phenotypic analysis, we first assessed the mass and fiber size of the soleus muscle, as well as the weight of heart and body, because the involvement of NUAK1 in myoblast differentiation has been implied (9). No difference was observed between MNUAK1KO and control mice with respect to body, heart, or soleus weights under both normal chow diet (NC) and HFD conditions at 13–15 weeks of age (Fig. 2, A and B, and supplemental Table S1). The myocyte cross-sectional area of the soleus muscle was almost identical in MNUAK1KO and control mice (Fig. 2C). The expression of NUAK1 in heart or soleus muscle of control mice was not affected by the HFD (data not shown).


Muscle-specific knock-out of NUAK family SNF1-like kinase 1 (NUAK1) prevents high fat diet-induced glucose intolerance.

Inazuka F, Sugiyama N, Tomita M, Abe T, Shioi G, Esumi H - J. Biol. Chem. (2012)

MNUAK1KO mice display no morphological abnormalities.A and B, weight of heart (A) and soleus muscle (B) of control and MNUAK1KO mice fed a NC or HFD. The indicated values are normalized to body weight. The data are the means ± S.E. (n = 10). C, cross-section of soleus muscle myocytes stained with wheat germ agglutinin. Scale bars, 20 μm. The graph below shows the average myocyte cross-sectional area for control and MNUAK1KO mice. The data are the means ± S.E. (n = 6). D–F, real time RT-PCR analysis of PGC-1α (D), TNNC1 (E), and TNNC2 (F). The mRNA levels are expressed relative to that of the soleus in control mice. The data are the means ± S.E. (n = 3). Mice at the age of 13–15 weeks were used for all experiments. Sol, soleus.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3351321&req=5

Figure 2: MNUAK1KO mice display no morphological abnormalities.A and B, weight of heart (A) and soleus muscle (B) of control and MNUAK1KO mice fed a NC or HFD. The indicated values are normalized to body weight. The data are the means ± S.E. (n = 10). C, cross-section of soleus muscle myocytes stained with wheat germ agglutinin. Scale bars, 20 μm. The graph below shows the average myocyte cross-sectional area for control and MNUAK1KO mice. The data are the means ± S.E. (n = 6). D–F, real time RT-PCR analysis of PGC-1α (D), TNNC1 (E), and TNNC2 (F). The mRNA levels are expressed relative to that of the soleus in control mice. The data are the means ± S.E. (n = 3). Mice at the age of 13–15 weeks were used for all experiments. Sol, soleus.
Mentions: For phenotypic analysis, we first assessed the mass and fiber size of the soleus muscle, as well as the weight of heart and body, because the involvement of NUAK1 in myoblast differentiation has been implied (9). No difference was observed between MNUAK1KO and control mice with respect to body, heart, or soleus weights under both normal chow diet (NC) and HFD conditions at 13–15 weeks of age (Fig. 2, A and B, and supplemental Table S1). The myocyte cross-sectional area of the soleus muscle was almost identical in MNUAK1KO and control mice (Fig. 2C). The expression of NUAK1 in heart or soleus muscle of control mice was not affected by the HFD (data not shown).

Bottom Line: Quantitative phosphoproteome analysis of soleus muscle was performed to understand the molecular mechanisms underlying the knock-out phenotype.Nuak1 mRNA was preferentially expressed in highly oxidative tissues such as brain, heart, and soleus muscle.Phosphoproteome analysis revealed that phosphorylation of IRS1 Ser-1097 was markedly decreased in NUAK1-deficient muscle.

View Article: PubMed Central - PubMed

Affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan.

ABSTRACT
NUAK1 is a member of the AMP-activated protein kinase-related kinase family. Recent studies have shown that NUAK1 is involved in cellular senescence and motility in epithelial cells and fibroblasts. However, the physiological roles of NUAK1 are poorly understood because of embryonic lethality in NUAK1 mice. The purpose of this study was to elucidate the roles of NUAK1 in adult tissues. We determined the tissue distribution of NUAK1 and generated muscle-specific NUAK1 knock-out (MNUAK1KO) mice. For phenotypic analysis, whole body glucose homeostasis and muscle glucose metabolism were examined. Quantitative phosphoproteome analysis of soleus muscle was performed to understand the molecular mechanisms underlying the knock-out phenotype. Nuak1 mRNA was preferentially expressed in highly oxidative tissues such as brain, heart, and soleus muscle. On a high fat diet, MNUAK1KO mice had a lower fasting blood glucose level, greater glucose tolerance, higher insulin sensitivity, and higher concentration of muscle glycogen than control mice. Phosphoproteome analysis revealed that phosphorylation of IRS1 Ser-1097 was markedly decreased in NUAK1-deficient muscle. Consistent with this, insulin signaling was enhanced in the soleus muscle of MNUAK1KO mice, as evidenced by increased phosphorylation of IRS1 Tyr-608, AKT Thr-308, and TBC1D4 Thr-649. These observations suggest that a physiological role of NUAK1 is to suppress glucose uptake through negative regulation of insulin signaling in oxidative muscle.

Show MeSH
Related in: MedlinePlus