Scientists are investigating a group of nuclear receptors that could offer new insights into how cells regulate mitochondria, energy use, and muscle function.
Energy metabolism is one of biology's most fundamental physiological processes. Every cell requires a continuous energy supply to maintain its functions, with tissues such as skeletal muscle and the heart having particularly high energy demands. Consequently, understanding how cells regulate energy production has become a key topic in modern biomedical research.
The estrogen-related receptor (ERR) family is attracting increasing attention. Despite their name suggesting a link to estrogen, ERRs are distinct from classical estrogen receptors. ERRα, ERRβ, and ERRγ are nuclear receptors that regulate genes involved in mitochondrial function, oxidative phosphorylation, fatty acid metabolism, and cellular energy utilization.
Recent studies highlight the potential of experimental compounds to target these receptors, giving scientists new tools to investigate energy metabolism and muscle physiology.
Why Are ERRs Crucial for Cellular Energy Regulation?
Cells do not produce energy at a constant rate; energy production fluctuates based on the needs of different tissues and physiological conditions. Mitochondria play a central role in this process. These cellular structures primarily convert nutrients into usable energy through oxidative phosphorylation. Tissues with high energy demands, such as skeletal and cardiac muscle, rely heavily on efficient mitochondrial activity.
ERRs help regulate many of the genes responsible for these processes.
Research indicates that ERR signaling pathways are closely linked to mitochondrial biogenesis, fatty acid oxidation, the tricarboxylic acid (TCA) cycle (or Krebs cycle), and other metabolic pathways. In skeletal muscle, these receptors are also associated with physiological adaptations during aerobic exercise.
This makes ERRs a focal point for researchers studying diseases characterized by impaired energy metabolism or muscle function.
Researchers do not view ERR activation as an established treatment for metabolic diseases; rather, they are investigating this pathway to better understand the relationships among gene regulation, mitochondrial activity, and tissue function.
New Generation of Compounds for ERR Research
Growing interest in ERR signaling pathways has prompted researchers to develop small-molecule compounds that can activate various ERR subtypes. SLU-PP-915 is one such example; it is an experimental small-molecule pan-ERR (estrogen-related receptor) agonist. The compound originated from research aimed at developing novel chemical structures that activate ERR pathways. A 2023 study characterized SLU-PP-915 as a novel substituted thiophene compound and reported its activity against multiple ERR subtypes. Researchers also observed increased expression of several ERR-related target genes in laboratory experiments. The compound drew further attention after a 2026 study examined its impact on aerobic exercise capacity.
Unlike some earlier ERR agonists, SLU-PP-915 was designed for oral bioavailability. This attribute is crucial for researchers, as orally active compounds offer greater flexibility for long-term preclinical studies and pharmacological exploration. This feature also helps explain why SLU-PP-915's significance extends beyond basic receptor research; scientists can use the compound to investigate the effects of systemic ERR pathway activation over an extended period.
What did the latest research reveal?
A 2026 study examined SLU-PP-915's effects on aerobic exercise capacity in mice. Researchers compared the compound with an earlier pan-ERR agonist, SLU-PP-332. The study found that SLU-PP-915 improved running performance in mice, increasing both running distance and duration. Researchers also reported that the compound remained active when administered orally.
This study examined far more than just physical performance.
Researchers measured Ddit4-a gene linked to the biological response to aerobic exercise-as well as markers associated with mitochondrial gene expression. SLU-PP-915 induced Ddit4 expression in skeletal muscle; researchers reported that the compound acted synergistically with exercise training to further boost Ddit4 and mitochondrial gene expression. These findings are significant because they suggest that activating ERR (estrogen-related receptors) may influence specific molecular pathways involved in the body's response to exercise.
However, interpret these results with caution.
The study was conducted on mice rather than humans. Improvements in running capacity in animal models do not necessarily mean that the same compound would improve athletic performance, metabolic health, or physical function in humans.
From Exercise Biology to Metabolic Research
The broader significance of ERR research lies in the biological pathways involved. Since ERRs regulate genes linked to mitochondrial activity and energy metabolism, researchers are exploring whether modulating these receptors could offer insights into various diseases associated with impaired cellular energy regulation. Future areas for exploration include metabolic disorders, cardiovascular diseases, and muscle-related conditions. The scientific value of compounds like SLU-PP-915 lies in their ability to help researchers probe the specific biological pathways typically involved in exercise adaptation.
By isolating and studying these pathways individually, scientists may better understand how muscles regulate energy production, how mitochondria respond to metabolic demands, and how gene expression shifts under physiological stress.
What Does ERR Research Mean for Future Drug Development?
The development of orally active ERR agonists marks a significant advance in this field of research.
Early experimental compounds demonstrated that ERR activation could influence pathways related to metabolism and exercise. The development of SLU-PP-915 provides a new research tool with distinct chemical properties and oral bioavailability. Researchers now need to determine the long-term effects of ERR activation across tissues, whether these effects remain consistent over time, and whether potential benefits can be achieved without adverse reactions. Currently, SLU-PP-915's significance lies primarily in science. It offers researchers a novel avenue to investigate the interrelationships among nuclear receptor signaling, mitochondrial biology, energy metabolism, and muscle physiology. As scientists continue to elucidate the molecular
pathways underlying energy regulation, ERR is likely to assume an increasingly important role in this field of research.
Recent findings have not established new therapies for metabolic or muscle disorders; instead, they have revealed a broader scientific opportunity: gaining a deeper understanding of how specific nuclear receptors regulate relevant genes to enable high-energy-demand tissues to adapt to changing requirements. The value of this topic extends far beyond exercise research, holding particular significance as researchers continue to explore new ways to understand mitochondrial function and metabolic diseases.