Oxidative stress makes the difference between metabolically abnormal and healthy forms of obesity
Osaka University | 04-25-2018
Scientists at Osaka University have discovered that elimination of adipose tissue oxidative stress (Fat ROS) decreases lipid accumulation in the liver, clinically improving insulin resistance and inducing metabolically healthy obesity. Their research results were published in Diabetes on April 4, 2018.
In most people, obesity is caused by eating too much and moving too little. There are two types of obesity: metabolically abnormal obesity associated with insulin resistance and metabolic disorder and metabolically healthy obesity without these complicating disorders. However, the molecular mechanism behind this difference was unknown.
In 2004, a group of researchers led by Atsunori Fukuhara reported that oxidative stress increased in the obese adipose tissues. However, it was difficult to create a mouse model in which oxidative stress was manipulated to target adipocytes. So, the causal role of Fat ROS in obesity in vivo still remained unclear.
In the present study, the research team established several important findings. Fat ROS-eliminated mice, in which two antioxidant enzymes (Catalase and Sod1) were overexpressed in adipocytes using an adipocyte-specific aP2 promoter cassette, exhibited adipose expansion with decreased ectopic lipid accumulation and improved insulin sensitivity. Conversely, Fat ROS-augmented, Adipoq promoter-driven Cre transgenic mice, in which the antioxidant glutathione was depleted specifically in adipocytes, exhibited restricted adipose expansion associated with increased ectopic lipid accumulation and deteriorated insulin sensitivity.
SREBF1 transcriptional activities were suppressed by oxidative stress, suppressing expression of lipogenic genes in adipocytes, which was found to be the underlying mechanism for suppression of de novo lipogenesis by oxidative stress.
The results of this study could lead to the development of drugs targeting Fat ROS to induce healthy adipose expansion and lead to the treatment of obese type 2 diabetes.
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Materials provided by Osaka University. Content may be edited for clarity, style, and length.
