Molecular Mechanisms of Apoptosis Induced by Ajoene in 3T3-L1 Adipocytes

Authors

  • Jeong-Yeh Yang,

    1. Department of Animal and Dairy Science, University of Georgia, Athens, Georgia.
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  • Mary Anne Della-Fera,

    1. Department of Animal and Dairy Science, University of Georgia, Athens, Georgia.
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  • Cass Nelson-Dooley,

    1. Department of Animal and Dairy Science, University of Georgia, Athens, Georgia.
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  • Clifton A. Baile

    Corresponding author
    1. Department of Animal and Dairy Science, University of Georgia, Athens, Georgia.
    2. Department of Foods and Nutrition, University of Georgia, Athens, Georgia.
      444 Edgar L. Rhodes Center for Animal and Dairy Science, University of Georgia, Athens, GA 30602-2771. E-mail: cbaile@uga.edu
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  • The costs of publication of this article were defrayed, in part, by the payment of page charges. This article must, therefore, be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

444 Edgar L. Rhodes Center for Animal and Dairy Science, University of Georgia, Athens, GA 30602-2771. E-mail: cbaile@uga.edu

Abstract

Objective: Determine the biochemical pathways involved in induction of apoptosis by ajoene, an organosulfur compound from garlic.

Research Methods and Procedures: Mature 3T3-L1 adipocytes were incubated with ajoene at concentrations up to 200 μM. Viability and apoptosis were quantified using an MTS-based cell viability assay and an enzyme-linked immunosorbent assay for single-stranded DNA (ssDNA), respectively. Intracellular reactive oxygen species (ROS) production was measured based on production of the fluorescent dye, dichlorofluorescein. Activation of the mitogen-activated protein kinases extracellular signal-regulating kinase 1/2 (ERK) and c-Jun-N-terminal kinase (JNK) was shown by Western blot. Western blot was also used to show activation of caspase-3, translocation of apoptosis-inducing factor (AIF) from mitochondria to nucleus, and cleavage of 116-kDa poly(ADP-ribose) polymerase (PARP)-1.

Results: Ajoene induced apoptosis of 3T3-L1 adipocytes in a dose- and time-dependent manner. Ajoene treatment resulted in activation of JNK and ERK, translocation of AIF from mitochondria to nucleus, and cleavage of 116-kDa PARP-1 in a caspase-independent manner. Ajoene treatment also induced an increase in intracellular ROS level. Furthermore, the antioxidant N-acetyl-l-cysteine effectively blocked ajoene-mediated ROS generation, activation of JNK and ERK, translocation of AIF, and degradation of PARP-1.

Discussion: These results indicate that ajoene-induced apoptosis in 3T3-L1 adipocytes is initiated by the generation of hydrogen peroxide, which leads to activation of mitogen-activated protein kinases, degradation of PARP-1, translocation of AIF, and fragmentation of DNA. Ajoene can, thus, influence the regulation of fat cell number through the induction of apoptosis and may be a new therapeutic agent for the treatment of obesity.

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