LAUSR

Abstract Disclosure: S. Krylova: None. A. Landgraf: None. S. Sidoli: None. J. Pessin: None. It is well known that premenopausal females are relatively protected against metabolic dysfunction-associated steatotic liver disease (MASLD) compared to postmenopausal females and males. Recently, N6-methyladenosine (m6A) RNA methylation has been shown to protect against MASLD. Higher m6A abundance on RNA globally has been associated with lower levels of lipogenesis and hepatic steatosis. Furthermore, it has been reported that m6A levels drop in steatosis-susceptible male mice placed on HFD, while in steatosis-protected females on HFD m6A levels remain relatively high. While this data demonstrates that m6A methylation might explain the selective protection of females against hepatic steatosis on HFD, it is currently not known what drives the differences in m6A RNA methylation levels between males and females on HFD. Given that the precursor of m6A is S-adenosylmethionine (SAM), a product of the methionine cycle of one-carbon metabolism, and that certain one-carbon metabolites are known to be affected by estrogen levels, we hypothesized that estrogen-driven differences in one-carbon metabolism between males and females on HFD are responsible for their differences in liver m6A levels. In the livers of young male, female, and ovariectomized female mice on normal chow diet (NCD) and HFD, we measured the levels of m6A RNA methylation, as well as the levels of key enzymes of the methionine cycle and of m6A precursor, SAM. Similarly to m6A, levels of SAM were significantly lower in male compared to female livers on HFD. Furthermore, expression of key methionine cycle enzymes, such as Mtr and Ahcy, was significantly lower in livers of males and ovariectomized females compared to wild type females on HFD. These results demonstrate that in female livers on HFD the methionine cycle, under the regulation of estrogen, is upregulated to drive higher levels of SAM availability and, potentially, m6A RNA methylation. We are currently repeating these experiments in an additional group of male mice supplemented with Folic Acid (known to upregulate SAM) to demonstrate causative, rather than correlative relationship between the methionine cycle and m6A. Completing these experiments will allow me to establish a novel estrogen – SAM – m6A axis, which has strong implications in MASLD protection and can be utilized for development of targeted therapies for males and postmenopausal females in the future. Presentation: Saturday, July 12, 2025