Removing Muscle Protein Miro1 Restored Insulin Response in Lab Models
A buildup of the protein Miro1 in muscle impairs insulin response in type 2 diabetes, a new study reports. Here is how it was found and what is still unknown.
People with type 2 diabetes carry more of a protein called Miro1 in their skeletal muscles, and in preclinical experiments, taking the protein away brought back the muscles’ normal response to insulin. The study, published in Nature Communications, also found that aerobic exercise lowered Miro1 levels in people with the disease.
The work comes from a team at Pennington Biomedical Research Center, part of LSU, and points to a possible new target for drugs aimed at insulin resistance. It does not yet show that any such drug would be safe or work in people.
A protein on the cell’s power plants
Miro1, short for Mitochondrial Rho GTPase1, sits on the outer membrane of mitochondria, the small structures that make energy inside cells. The researchers propose that when too much of it builds up in muscle, the tissue becomes less able to react to insulin, the hormone that moves sugar out of the blood. That condition, called insulin resistance, is central to type 2 diabetes.
Senior author John P. Kirwan said the molecular causes of muscle insulin resistance “have remained frustratingly unclear” before this work.
How the team tested the idea
The scientists followed Miro1 through three kinds of studies. They worked with cells grown in the lab, then with preclinical models, which in this kind of research usually means animals, and finally with people who have type 2 diabetes. The press materials do not say which animals were used.
In the preclinical models, removing Miro1 restored the muscles’ response to insulin. The authors present this as evidence that the protein directly contributes to the problem, rather than simply showing up alongside it.
The human part was a randomized controlled trial in people with obesity and type 2 diabetes. One group did aerobic exercise and the other received standard medical care. In the exercise group, Miro1 fell in muscle tissue, and insulin sensitivity and the muscles’ ability to produce energy improved at the same time. The release did not give the number of participants.
What is still unclear
The two strongest results come from different settings. The direct test, where removing Miro1 restored insulin response, was done only in preclinical models. In people, the trial showed that Miro1 dropped while insulin sensitivity improved, which fits the idea but does not prove that lower Miro1 caused the improvement. Exercise changes many things in muscle at once.
The research center itself notes that scientists still have to find out whether a treatment aimed directly at Miro1 could be safe and effective. No such drug exists yet, and the study did not test one.
Why it matters for diabetes research
Doctors have long known that exercise improves how muscles handle insulin, but the steps inside the cell are only partly understood. If lower Miro1 is one of those steps, it gives researchers a specific molecule to study and, eventually, to target with drugs that might work alongside physical activity. Kirwan described Miro1 as “a new therapeutic target” for the field.
The study’s first author is Elizabeth Heintz, a doctoral candidate in Pennington Biomedical’s Integrated Physiology and Molecular Medicine Laboratory. Christopher Axelrod is co-corresponding author. The paper’s DOI is 10.1038/s41467-026-77278-6.
Where the work goes next
Kirwan has since become executive director of the OU Health Harold Hamm Diabetes Center at the University of Oklahoma, and Axelrod has joined him there. Kirwan plans to keep studying Miro1 with a mix of lab experiments and studies in people. Funding came from several National Institutes of Health institutes, including the National Institute of Diabetes and Digestive and Kidney Diseases and the National Institute on Aging.
Source: ScienceDaily
