Role of the atypical protein kinase Cζ in regulation of 5′-AMP-activated protein kinase in cardiac and skeletal muscle

2009 ◽  
Vol 297 (2) ◽  
pp. E349-E357 ◽  
Author(s):  
John R. Ussher ◽  
Jagdip S. Jaswal ◽  
Cory S. Wagg ◽  
Heather E. Armstrong ◽  
David G. Lopaschuk ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Muscle Cells ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Minor Role ◽  
Atypical Protein Kinase ◽  
Downstream Target ◽  
Ampk Phosphorylation ◽  
Amp Activated Protein Kinase

During metabolic stress, phosphorylation and activation of 5′-AMP-activated protein kinase (AMPK) becomes a major regulator of cellular energy metabolism in heart and skeletal muscle. Despite this, the upstream regulation of AMPK in both heart and muscle is poorly understood. Recent work has implicated the atypical protein kinase Cζ (PKCζ) as a regulator of AMPK in endothelial cells via phosphorylation of LKB1, an upstream AMPK kinase (AMPKK). Our goal was to determine the potential role PKCζ plays in regulating AMPK in cardiac and skeletal muscle. Cultures of H9c2 myocytes (cardiac) and C2C12 myotubes (skeletal muscle) were pretreated with a selective PKCζ pseudosubstrate peptide inhibitor and treated with various AMPK activating agents to determine whether PKCζ regulates AMPK. PKCζ activity was also examined in isolated working rat hearts subjected to ischemia. We show that PKCζ is not involved in regulating threonine 172 AMPK phosphorylation induced by metformin or phenformin in either cardiac or skeletal muscle cells but is involved in 5-aminoimidazole-4-carboxamine-1-β-d-ribofuranoside (AICAR)-induced AMPK phosphorylation in cardiac muscle cells. Activation of PKCζ with high palmitate concentrations is also insufficient to increase AMPK phosphorylation. Furthermore, we show that the ischemia-induced activation of AMPK is not accompanied by increased PKCζ activity. Finally, we show that PKCζ may actually be a downstream target of AMPK in skeletal muscle, since adenoviral expression of a dominant-negative mutant of AMPK prevented metformin- and AICAR-induced phosphorylation of PKCζ. We conclude that PKCζ plays a very minor role in the regulation of AMPK in cardiac and skeletal muscle and may actually be a downstream target of AMPK in skeletal muscle.

Activation of AMPK is essential for AICAR-induced glucose uptake by skeletal muscle but not adipocytes

2002 ◽  
Vol 282 (6) ◽  
pp. E1239-E1244 ◽  
Author(s):  
Hideyuki Sakoda ◽  
Takehide Ogihara ◽  
Motonobu Anai ◽  
Midori Fujishiro ◽  
Hiraku Ono ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Muscle Cells ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Ampk Activation ◽  
Wild Type ◽  
Rat Soleus Muscle ◽  
Amp Activated Protein Kinase

5-Aminoimidazole-4-carboxamide ribonucleoside (AICAR) reportedly activates AMP-activated protein kinase (AMPK) and stimulates glucose uptake by skeletal muscle cells. In this study, we investigated the role of AMPK in AICAR-induced glucose uptake by 3T3-L1 adipocytes and rat soleus muscle cells by overexpressing wild-type and dominant negative forms of the AMPKα2 subunit by use of adenovirus-mediated gene transfer. Overexpression of the dominant negative mutant had no effect on AICAR-induced glucose transport in adipocytes, although AMPK activation was almost completely abolished. This suggests that AICAR-induced glucose uptake by 3T3-L1 adipocytes is independent of AMPK activation. By contrast, overexpression of the dominant negative AMPKα2 mutant in muscle markedly suppressed both AICAR-induced glucose uptake and AMPK activation, although insulin-induced uptake was unaffected. Overexpression of the wild-type AMPKα2 subunit significantly increased AMPK activity in muscle but did not enhance glucose uptake. Thus, although AMPK activation may not, by itself, be sufficient to increase glucose transport, it appears essential for AICAR-induced glucose uptake in muscle.

scholarly journals AMP-Activated Protein Kinase-Regulated Activation of the PGC-1α Promoter in Skeletal Muscle Cells

PLoS ONE ◽  
2008 ◽  
Vol 3 (10) ◽  
pp. e3614 ◽  
Author(s):  
Isabella Irrcher ◽  
Vladimir Ljubicic ◽  
Angie F. Kirwan ◽  
David A. Hood
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Amp Activated Protein Kinase

scholarly journals Adiponectin improves insulin sensitivity via activation of autophagic flux

2017 ◽  
Vol 59 (4) ◽  
pp. 339-350 ◽  
Author(s):  
Penny Ahlstrom ◽  
Esther Rai ◽  
Suharto Chakma ◽  
Hee Ho Cho ◽  
Palanivel Rengasamy ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Er Stress ◽  
Western Blotting ◽  
Muscle Cells ◽  
Dominant Negative ◽  
Skeletal Muscle Cells ◽  
Dominant Negative Mutant ◽  
Autophagic Flux

Skeletal muscle insulin resistance is known to play an important role in the pathogenesis of diabetes, and one potential causative cellular mechanism is endoplasmic reticulum (ER) stress. Adiponectin mediates anti-diabetic effects via direct metabolic actions and by improving insulin sensitivity, and we recently demonstrated an important role in stimulation of autophagy by adiponectin. However, there is limited knowledge on crosstalk between autophagy and ER stress in skeletal muscle and in particular how they are regulated by adiponectin. Here, we utilized the model of high insulin/glucose (HIHG)-induced insulin resistance, determined by measuring Akt phosphorylation (T308 and S473) and glucose uptake in L6 skeletal muscle cells. HIHG reduced autophagic flux measured by LC3 and p62 Western blotting and tandem fluorescent RFP/GFP-LC3 immunofluorescence (IF). HIHG also induced ER stress assessed by thioflavin T/KDEL IF, pIRE1, pPERK, peIF2α and ATF6 Western blotting and induction of a GRP78-mCherry reporter. Induction of autophagy by adiponectin or rapamycin attenuated HIHG-induced ER stress and improved insulin sensitivity. The functional significance of enhanced autophagy was validated by demonstrating a lack of improved insulin sensitivity in response to adiponectin in autophagy-deficient cells generated by overexpression of dominant negative mutant of Atg5. In summary, adiponectin-induced autophagy in skeletal muscle cells alleviated HIHG-induced ER stress and insulin resistance.

Signal transduction pathways of IL-1β-mediated iNOS in pulmonary vascular smooth muscle cells

2001 ◽  
Vol 281 (4) ◽  
pp. L816-L823 ◽  
Author(s):  
Jonathan D. Finder ◽  
Jennifer L. Petrus ◽  
Andrew Hamilton ◽  
Raphael T. Villavicencio ◽  
Bruce R. Pitt ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase ◽  
Pulmonary Artery ◽  
Smooth Muscle Cells ◽  
Intracellular Signaling ◽  
Muscle Cells ◽  
Dominant Negative ◽  
Janus Kinase ◽  
Dominant Negative Mutant ◽  
Pulmonary Artery Smooth Muscle

Interleukin (IL)-1β is an important early mediator of inflammation in pulmonary artery smooth muscle cells. We previously reported that a geranylgeranyltransferase inhibitor elevated basal levels of inducible nitric oxide synthase (iNOS) and enhanced IL-1β-mediated induction, suggesting that Rac or Rho small G proteins are candidates for antagonism of such induction. In this study, overexpression of constitutively active Rac1 or its dominant negative mutant did not affect IL-1β induction of iNOS. Alternatively, treatment with Clostridium botulinum C3 exoenzyme, which ADP-ribosylates Rho, was associated with superinduction of iNOS, suggesting an inhibitory role for Rho. IL-1β activated the three mitogen-activated protein kinase (extracellular signal-regulated kinases 1 and 2, c-Jun NH2-terminal kinase/stress-activated protein kinase, and p38) and the Janus kinase (JAK)-signal transducer and activator of transcription pathways. The former two pathways were not associated with IL-1β-mediated iNOS induction, whereas the latter two appeared to have inhibitory roles in iNOS expression. These data suggest that a broad intracellular signaling response to IL-1β in rat pulmonary artery smooth muscle cells results in elevated levels of iNOS that is opposed by the geranylgeranylated small G protein Rho as well as the p38 and JAK2 pathways.

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