Activation of the Cytoplasmic c-Abl Tyrosine Kinase by Reactive Oxygen Species

NADPH oxidase (Nox) family enzymes are one of the main sources of cellular reactive oxygen species (ROS), which have been shown to function as second messenger molecules. To date, seven members of this family have been reported, including Nox1-5 and Duox1 and -2. With the exception of Nox2, the regulation of the Nox enzymes is still poorly understood. Nox1 is highly expressed in the colon, and it requires two cytosolic regulators, NoxO1 and NoxA1, as well as the binding of Rac1 GTPase, for its activity. In this study, we investigate the role of the tyrosine kinase c-Src in the regulation of ROS formation by Nox1. We show that c-Src induces Nox1-mediated ROS generation in the HT29 human colon carcinoma cell line through a Rac-dependent mechanism. Treatment of HT29 cells with the Src inhibitor PP2, expression of a kinase-inactive form of c-Src, and c-Src depletion by small interfering RNA (siRNA) reduce both ROS generation and the levels of active Rac1. This is associated with decreased Src-mediated phosphorylation and activation of the Rac1-guanine nucleotide exchange factor Vav2. Consistent with this, Vav2 siRNA that specifically reduces endogenous Vav2 protein is able to dramatically decrease Nox1-dependent ROS generation and abolish c-Src-induced Nox1 activity. Together, these results establish c-Src as an important regulator of Nox1 activity, and they may provide insight into the mechanisms of tumor formation in colon cancers.

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Cucurbitacin I Inhibits Rac1 Activation in Breast Cancer Cells by a Reactive Oxygen Species-Mediated Mechanism and Independently of Janus Tyrosine Kinase 2 and P-Rex1

Molecular Pharmacology ◽

10.1124/mol.112.084293 ◽

2013 ◽

Vol 83 (5) ◽

pp. 1141-1154 ◽

Cited By ~ 31

Author(s):

Cynthia Lopez-Haber ◽

Marcelo G. Kazanietz

Keyword(s):

Breast Cancer ◽

Reactive Oxygen Species ◽

Tyrosine Kinase ◽

Cancer Cells ◽

Breast Cancer Cells ◽

Reactive Oxygen ◽

Oxygen Species ◽

Tyrosine Kinase 2 ◽

Janus Tyrosine Kinase 2

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Nuclear Abl Drives miR-34c Transfer by Extracellular Vesicles to Induce Radiation Bystander Effects

10.1101/209767 ◽

2017 ◽

Author(s):

Shubhra Rastogi ◽

Amini Hwang ◽

Josolyn Chan ◽

Jean YJ Wang

Keyword(s):

Reactive Oxygen Species ◽

Dna Damage ◽

Ionizing Radiation ◽

Extracellular Vesicles ◽

Reactive Oxygen ◽

Nuclear Accumulation ◽

Oxygen Species ◽

Bystander Effects ◽

Abl Tyrosine Kinase ◽

Radiation Induced

SUMMARYIonizing radiation stimulates nuclear accumulation of Abl tyrosine kinase that is required for directly irradiated cells to produce microRNA-34c-containing extracellular vesicles, which transfer the microRNA into non-irradiated cells to induce reactive oxygen species and bystander DNA damage.ABSTRACTIonizing radiation (IR) activates an array of DNA damage response (DDR) that includes the induction of bystander effects (BE) in cells not targeted by radiation. How DDR pathways in irradiated cells stimulate BE in non-targeted cells is mostly unknown. We show here that extracellular vesicles from irradiated cells (EV-IR) induce reactive oxygen species (ROS) and DNA damage when internalized by un-irradiated cells. We found that EV-IR from Abl-NLS-mutated cells could not induce ROS or DNA damage, and restoration of nuclear Abl rescued those defects. Expanding a previous finding that Abl stimulates miR-34c expression, we show here that nuclear Abl also drives the vesicular secretion of miR-34c. Ectopic miR-34c expression, without irradiation, generated EV-miR-34c capable of inducing ROS and DNA damage. Furthermore, EV-IR from miR34-knockout cells could not induce ROS and raised γH2AX to lesser extent than EV-IR from miR34-wild type cells. These results establish a novel role for the Abl-miR-34c DDR pathway in stimulating radiation-induced bystander effects.

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