The role of reciprocal activation of cAbl and Mst1 in the oxidative death of cultured astrocytes.
The protein kinase Mst1 (mammalian Sterile 20-like kinase 1) likely plays a role in oxidative neuronal cell death as a target of its activator, cAbl. We previously found that H2O2-induced death of astrocytes is mediated by cAbl in a metallothionein-3 (Mt3)-dependent manner. In the present study, we examined a possible role for Mst1 in the oxidative death of astrocytes. Treatment of cortical astrocytes with 170 µM H2O2 activated Mst1. Knockdown of Mst1 reduced H2O2-induced cell death, indicating that Mst1 activation contributes to astrocytic cell death. STI571, an inhibitor of cAbl, blocked induction/activation of Mst1 and H2O2-induced cell death. However, Mst1 silencing also inhibited induction/activation of cAbl, suggesting that the two kinases are regulated by a reciprocal activating mechanism. The zinc chelator TPEN blocked induction/activation of cAbl and Mst1, indicating that these phenomena are dependent on the rise of intracellular zinc. Moreover, H2O2 exposure did not increase free zinc levels in Mt3-null astrocytes, suggesting that the increased levels of free zinc were largely from Mt3. Consistent with the involvement of FoxO1/3, which may play a role in the Mst1-cell death cascade, we found an increase in the level of phosphorylated FoxO1/3 in H2O2-treated astrocytes. Moreover, inhibition of cAbl or Mst1 reversed this effect. The present results suggest the interesting possibility that cAbl and Mst1 are reciprocally activated under oxidative stress conditions in astrocytes. Both kinases appear to be regulated by changes in the levels of free zinc originating from Mt3 and contribute to oxidative cell death through a FoxO-dependent mechanism.
Neural Injury Research Lab, University of Ulsan College of Medicine, Seoul, 138-736, Korea; Asan Institute for Life Science, University of Ulsan College of Medicine, Seoul, 138-736, Korea.
Sook-Jeong
SJ
Lee
Bo-Ra
BR
Seo
Eui-Ju
EJ
Choi
Jae-Young
JY
Koh
D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects / Q000502:physiology*; D001549:Benzamides / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D002614:Chelating Agents / Q000494:pharmacology; D005029:Ethylenediamines / Q000494:pharmacology; D017228:Hepatocyte Growth Factor / Q000235:genetics / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000633:toxicity*; D000068877:Imatinib Mesylate; D053513:Matrix Metalloproteinase 16 / Q000172:deficiency; D000090023:Metallothionein 3; D051379:Mice; D008822:Mice, Transgenic; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D010879:Piperazines / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D016315:Proto-Oncogene Proteins c-abl / Q000235:genetics / Q000378:metabolism*; D011743:Pyrimidines / Q000494:pharmacology; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics / Q000494:pharmacology; D015032:Zinc / Q000494:pharmacology
D001549:Benzamides; D002614:Chelating Agents; D005029:Ethylenediamines; D000090023:Metallothionein 3; C000715430:Mt3 protein, mouse; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D011743:Pyrimidines; D034741:RNA, Small Interfering; C082332:macrophage stimulating protein; D017228:Hepatocyte Growth Factor; D000068877:Imatinib Mesylate; D006861:Hydrogen Peroxide; D016315:Proto-Oncogene Proteins c-abl; D053513:Matrix Metalloproteinase 16; D015032:Zinc; C044387:N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine
astrocytic death; cAbl; metallothioneins; oxidative injury