New UCI study indicates that genetic sex determines how muscle tissue interacts with other tissues and organs

A new study by researchers at University of California, Irvine (UCI) indicates that an individual's genetic sex influences the way muscle tissue communicates with other other tissues and organs in the body.

According to a press release by UCI, the study, titled Genetic variation of putative myokine signaling is dominated by biologic sex and sex hormones, uncovered that muscles of genetic males and females use different circuits when signaling other tissues and organs. The study provides valuable insight into how muscle functions, such as exercise, can promote healthy longevity, metabolism and cognition.

“Muscle is critical for maintaining metabolic state, and disruption of muscle function is a hallmark of diseases such as obesity, type 2 diabetes and cardiovascular disease,” senior author Marcus Seldin, Ph.D., assistant professor of biological chemistry at UCI School of Medicine, said in the press release.

Muscles secrete proteins called myokines when interacting with other tissues, and the study found that virtually all significant cross-tissue or organ interactions were dependent on genetic sex or hormones, especially with estradiol. For example, muscle signals to the pancreas more in females, and in males, muscles signal more to the liver. 

“We already know that skeletal muscle plays an integral role in coordinating physiologic homeostasis. In this study, we sought to understand how muscle interacts with metabolic tissues and illustrate the importance of considering the effects of genetic sex and sexual hormones when studying metabolism,” Seldin said. 

The new information will provide further insight into muscle functions. The study was supported by the National Institutes of Health.