Down-regulation of Risa improves insulin sensitivity by enhancing autophagy

Area of Science:

• Molecular Biology
• Metabolic Diseases
• RNA Biology

Background:

• Small noncoding RNAs impact insulin sensitivity.
• The role of long noncoding RNAs in insulin sensitivity remains largely unexplored.

Purpose of the Study:

• To identify and characterize long noncoding RNAs involved in insulin sensitivity regulation.
• To investigate the mechanism by which Risa affects insulin sensitivity and autophagy.

Main Methods:

• Identification and characterization of Risa, a poly(A)(+) cytoplasmic long noncoding RNA.
• In vitro studies using mouse primary hepatocytes and C2C12 myotubes to assess Risa's effects on insulin signaling and autophagy.
• In vivo studies involving tail vein injection of adenovirus in C57BL/6 and ob/ob mice to evaluate Risa's impact on insulin sensitivity and hepatic autophagy.

Main Results:

• Overexpression of Risa attenuated insulin signaling, while its knockdown alleviated insulin resistance.
• Risa was found to inhibit autophagy; its knockdown enhanced autophagy.
• Knockdown of autophagy-related genes (Atg7, Atg5) diminished the beneficial effects of Risa knockdown on insulin resistance.
• In vivo knockdown of Risa improved insulin sensitivity and hepatic autophagy in mouse models.

Conclusions:

• Risa negatively regulates insulin sensitivity by suppressing autophagy.
• Down-regulation of Risa enhances autophagy, leading to improved insulin sensitivity.
• Risa represents a potential therapeutic target for treating insulin resistance and related metabolic disorders.