scholarly journals Partial purification and characterization of a wortmannin-sensitive and insulin-stimulated protein kinase that activates heart 6-phosphofructo-2-kinase

2000 ◽  
Vol 347 (1) ◽  
pp. 305-312 ◽  
Author(s):  
Johan DEPREZ ◽  
Luc BERTRAND ◽  
Dario R. ALESSI ◽  
Ulrike KRAUSE ◽  
Louis HUE ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Kinase Inhibitors ◽  
Insulin Signalling ◽  
Gel Filtration ◽  
Protein Kinase Inhibitors ◽  
Partial Purification ◽  
Dependent Manner ◽  
Rat Hearts ◽  
Insulin Signalling Pathway ◽  
Perfused Rat Hearts

A wortmannin-sensitive and insulin-stimulated protein kinase (WISK), which phosphorylates and activates cardiac 6-phosphofructo-2-kinase (PFK-2), was partially purified from perfused rat hearts. Immunoblotting showed that WISK was devoid of protein kinase B (PKB), serum- and glucocorticoid-regulated protein kinase and protein kinase Cζ (PKCζ). Comparison of the inhibition of WISK, PKCα and PKCζ by different protein kinase inhibitors suggested that WISK was not a member of the PKC family. In addition, WISK contained no detectable phosphoinositide-dependent protein kinase-1 (PDK1) activity. WISK phosphorylated recombinant heart PFK-2 in a time-dependent manner to the extent of 0.4 mol of phosphate incorporated/mol of enzyme subunit, and increased the Vmax of PFK-2 twofold, without affecting the Km for fructose 6-phosphate. WISK phosphorylated Ser-466 to a greater extent than Ser-483 in recombinant heart PFK-2, and both sites were demonstrated to be phosphorylated to the same extent by PKB. Gel filtration and in-gel kinase analysis indicated that WISK was a monomer with a Mr of 56500. Treatment of WISK with protein phosphatase 2A (PP2A) catalytic subunits reversed the effect of insulin, suggesting the involvement of an upstream activating kinase. Indeed, PDK1 was able to partially reactivate the PP2A-treated WISK and this reactivation was not enhanced by PtdIns(3,4,5)P3-containing vesicles. Moreover, a single 57000-Mr band was labelled on incubation of the dephosphorylated WISK preparation with PDK1 and [γ-32P]ATP. These findings provide evidence for the existence of a new protein kinase in the insulin signalling pathway, probably downstream of PDK1.

Euodia daniellii Hemsl. (Bee-Bee Tree) Oil Attenuates Palmitate-Induced Lipid Accumulation and Apoptosis in Hepatocytes

Pharmacology ◽  
2018 ◽  
Vol 101 (5-6) ◽  
pp. 298-308
Author(s):  
Tae Woo Jung ◽  
Sun-Young Kim ◽  
Da-Som Kim ◽  
Eui-Cheol Shin ◽  
Yong Bae Park ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Protein Kinase ◽  
Saturated Fatty Acid ◽  
Lipid Accumulation ◽  
Caspase 3 ◽  
Kinase Inhibitors ◽  
Adenosine Monophosphate ◽  
Protein Kinase Inhibitors ◽  
Dependent Manner ◽  
Protective Effects

Hepatic lipid accumulation and apoptosis is elevated in patients with non-alcoholic steatohepatitis and is closely associated with severity. Saturated fatty acid palmitate stimulates lipid accumulation and apoptosis in hepatocytes. In the present study, we examined bee-bee tree oil (BO)-mediated protective effects on palmitate-induced lipid accumulation and apoptosis in mouse primary hepatocytes. Cells were cultured in a control media or the same media containing 150 or 300 µmol/L of albumin-bound palmitate for 24 h. BO concentrations used were 0, 0.1, 0.2, or 0.5%. Palmitate induced lipid accumulation and mRNA expression of lipogenic genes such as SREBP1c and SCD1. However, BO prevented these changes. Furthermore, palmitate stimulated caspase-3 activity and decreased cell viability in the absence of BO. BO reduced palmitate-induced activation of caspase-3 and cell death in a dose-dependent manner. AMP-activated protein kinase inhibitors abolished the effects of BO. Furthermore, BO suppressed palmitate-induced c-Jun N-terminal kinase (JNK) phosphorylation through the 5' adenosine monophosphate-activated protein kinase (AMPK)-dependent pathway. In conclusion, BO attenuated palmitate-induced hepatic steatosis and apoptosis through AMPK-mediated suppression of JNK signaling. These data suggest that BO is an important determinant of saturated fatty acid-induced lipid accumulation and apoptosis, and may be an effective therapeutic strategy for treatment of obesity-mediated liver diseases.

scholarly journals Regulation of the antigen-induced F-actin response in rat basophilic leukemia cells by protein kinase C.

1991 ◽  
Vol 112 (6) ◽  
pp. 1157-1163 ◽  
Author(s):  
J R Apgar
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Kinase Inhibitors ◽  
Protein Kinase Inhibitors ◽  
Induced Response ◽  
Dependent Manner ◽  
Filamentous Actin ◽  
Kinase C ◽  
Rbl Cells ◽  
Basophilic Leukemia

Multivalent antigen that is capable of binding to and crosslinking the IgE receptors on rat basophilic leukemia (RBL) cells, induces a rapid and sustained rise in the content of filamentous actin. This reorganization of the actin may be responsible for changes in cellular morphology during the degranulation process. The antigen-stimulated polymerization of actin can be blocked in a dose-dependent manner by protein kinase inhibitors which also block degranulation. Conversely, reagents such as PMA, 1,2-dioctanoyl-sn-glycerol (diC8), and 1-oleoyl-2-acetyl-glycerol (OAG) which stimulate protein kinase C (PKC) also activate the rise in F-actin, although they have no effect on degranulation by themselves. The actin response which can be stimulated by the PKC activators can also be blocked by protein kinase inhibitors indicating that the PMA- and OAG-induced response is probably through activation of a protein kinase. Depletion of PKC activity through long term (20 h) exposure of RBL cells to PMA, also inhibited the F-actin response when the cells were stimulated with either multivalent antigen or OAG. External Ca++, which is an absolute requirement for degranulation, is not necessary for the rise in F-actin, but may modulate the response. Furthermore, ionomycin, which induces a large Ca++ influx, does not stimulate the F-actin increase even at doses that cause degranulation. These results suggest that activation of a protein kinase, such as PKC, may be responsible for signaling the polymerization of actin in RBL cells and that a rise in intracellular Ca++ is neither necessary nor sufficient for this response.

scholarly journals Thiazolidine-diones. Biochemical and biological activity of a novel class of tyrosine protein kinase inhibitors.

1990 ◽  
Vol 265 (36) ◽  
pp. 22255-22261
Author(s):  
J F Geissler ◽  
P Traxler ◽  
U Regenass ◽  
B J Murray ◽  
J L Roesel ◽  
...  
Keyword(s):  
Biological Activity ◽  
Protein Kinase ◽  
Kinase Inhibitors ◽  
Protein Kinase Inhibitors ◽  
Tyrosine Protein Kinase
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