Transcriptomic analysis reveals niche gene expression effects of beta-hydroxybutyrate in primary myotubes

Abstract

Worldwide obesity rates are spiraling out of control. Inasmuch as obesity is a major risk factor for many chronic diseases, including type 2 diabetes, cardiovascular disease, and certain types of cancer, effective remedies to combat obesity rates are direly needed. Various forms of fasting, including time-restricted feeding, alternate day fasting or periodic fasting have shown promise in clinical and pre-clinical studies to normalize body weight, improve metabolic health and protect against disease. Recent studies suggest that β-hydroxybutyrate (βOHB), a characteristic ketone body of the fasted metabolic state, acts as a potential signaling molecule mediating the beneficial effects of the various fasting forms, potentially by acting as a HDAC inhibitor. In the first part we investigated whether βOHB, in comparison to the well established HDAC inhibitor butyrate, influences cellular differentiation in vitro. Neither in C2C12 myotubes, 3T3-L1 adipocytes nor THP-1 monocytes 5-8 mm βOHB altered differentiation based on gene expression and visual assessment. Equimolar concentrations of butyrate potently impaired differentiation processes in all cases. To further characterize the capacity of βOHB to regulate gene expression in an unbiased fashion we next subjected primary mouse adipocytes, macrophages, myotubes and hepatocytes to RNA-seq. In contrast to butyrate, βOHB minimally impacted gene expression. Overall our data do not support the notion that βOHB serves as a powerful signaling molecule regulating gene expression in adipocytes, macrophages and hepatocytes but may instead act as a niche signaling molecule for example, regulating immunity-related pathways in muscle.