m 6 A mRNA methylation in brown fat regulates systemic insulin sensitivity via an inter-organ prostaglandin signaling axis independent of UCP1.

Brown adipose tissue (BAT) regulates systemic metabolism by releasing signaling lipids. N ⁶ -methyladenosine (m ⁶ A) is the most prevalent and abundant post-transcriptional mRNA modification and has been reported to regulate BAT adipogenesis and energy expenditure. Here, we demonstrate that the absence of m ⁶ A methyltransferase-like 14 (METTL14) modifies the BAT secretome to improve systemic insulin sensitivity independent of UCP1. Using lipidomics, we identify prostaglandin E2 (PGE2) and prostaglandin F2a (PGF2a) as BAT-secreted insulin sensitizers. PGE2 and PGF2a inversely correlate with insulin sensitivity in humans and protect mice from high-fat-diet-induced insulin resistance by suppressing specific AKT phosphatases. Mechanistically, METTL14-mediated m ⁶ A promotes the decay of PTGES2 and CBR1, the genes encoding PGE2 and PGF2a biosynthesis enzymes, in brown adipocytes via YTHDF2/3. Consistently, BAT-specific knockdown of Ptges2 or Cbr1 reverses the insulin-sensitizing effects in M14 ^KO mice. Overall, these findings reveal a novel biological mechanism through which m ⁶ A-dependent regulation of the BAT secretome regulates systemic insulin sensitivity.
Competing Interests: Declaration of interests R.N.K. is on the scientific advisory boards of Novo Nordisk, Biomea, Inversago, and REDD. C.H. is a scientific founder and a member of the scientific advisory board of Accent Therapeutics. M.B. received honoraria as a consultant and speaker from Amgen, AstraZeneca, Bayer, Boehringer Ingelheim, Lilly, Novo Nordisk, Novartis, Pfizer, and Sanofi.
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