NR1D1 is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2025-03-14. Where a claim depends on a specific study, the study is described rather than over-claimed.
SR9009 is a synthetic small molecule developed as an agonist of the nuclear receptors REV-ERBα (NR1D1) and REV-ERBβ (NR1D2). These receptors help regulate circadian rhythms and metabolic gene expression. In cell and animal studies, SR9009 alters transcription of genes involved in lipid metabolism, inflammation, and mitochondrial function. It is not an approved medicine, and its pharmacological profile in humans remains largely uncharacterized. The compound is frequently discussed in the context of circadian biology and metabolic research rather than clinical use.
Preclinical reports have linked SR9009 to improved endurance and altered energy expenditure in rodents. Such findings have prompted interest in whether REV-ERB activation can influence skeletal muscle metabolism. However, the reported effects depend on dose, route, and experimental model, and replication across laboratories is limited. Human trials have not established comparable outcomes, so claims about exercise performance remain speculative. The absence of controlled human data is a central limitation in interpreting these observations.
SR9009 is a synthetic small molecule studied as an agonist of the nuclear receptors REV-ERBα and REV-ERBβ. These receptors help regulate circadian rhythms and metabolic gene expression. In laboratory experiments, SR9009 binds these receptors and alters transcription of genes involved in lipid handling, glucose metabolism, and mitochondrial function. It is not a naturally occurring compound and has no approved therapeutic use. Research interest stems from its ability to modify energy metabolism in cells and animal models.
In rodent studies, SR9009 has been reported to increase mitochondrial content in skeletal muscle and improve exercise endurance under some conditions. These findings led to popular descriptions such as an exercise mimetic, although that term oversimplifies the biology. Effects vary by dose, timing, tissue, and model. The compound's influence on circadian pathways means that time of administration can matter in experiments. Whether similar metabolic changes occur in humans remains largely unexplored in controlled published trials.
Pharmacokinetic data for SR9009 are limited in published literature. Some reports indicate low oral bioavailability and rapid clearance in animals, which complicates interpretation of exposure and effect. Researchers often use injected routes in preclinical work to achieve measurable systemic levels. Analytical studies rely on mass spectrometry to detect the parent compound and its metabolites. Questions about tissue distribution, active metabolites, and long-term consequences remain open. Species differences in metabolism can affect observed half-life and target engagement.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic REV-ERB agonist | Small molecule; not a steroid or peptide. |
| Primary targets | NR1D1 and NR1D2 | Also known as REV-ERBα and REV-ERBβ. |
| Studied routes | Intraperitoneal in rodents | Oral bioavailability in humans is not established. |
| Human approval | No approved therapeutic indication | No recognized clinical use. |
| Key uncertainty | Human physiological effects | Preclinical findings may not translate. |
SR9009 binds REV-ERB receptors and alters their repressive activity on target genes. This action can change transcription of genes involved in lipid handling, glucose metabolism, and mitochondrial function. In rodent studies, treated animals have shown changes in muscle oxidative capacity and exercise performance, though effects vary by dose, duration, and model. The precise molecular steps connecting receptor binding to whole-body outcomes are still an active area of investigation. Findings in animals do not automatically translate to humans.
Because REV-ERB receptors are core clock components, SR9009 has been examined for effects on daily rhythms as well as metabolism. Research has explored whether the compound can shift or reinforce circadian gene expression in tissues such as liver and muscle. Some studies report improved metabolic markers in obese or diabetic mice, while others show context-dependent responses. Questions remain about which effects are direct, which are secondary to timing, and how they might differ across species.
Analytical methods for SR9009 typically rely on liquid chromatography coupled with tandem mass spectrometry. The technique can separate the parent compound from related substances and detect low concentrations in biological matrices. Urine and blood are common samples in anti-doping testing, while in vitro studies may use cell culture media. Rapid metabolism and low expected concentrations make method validation important for reliable identification. Exact metabolite patterns can vary by species and are not fully mapped.
Regulatory treatment of SR9009 reflects its investigational status. The compound has no approved human therapeutic indication, and sports authorities prohibit its use. It appears on anti-doping lists as a non-approved substance or metabolic modulator, depending on the list version. Products sold online as research chemicals are not quality-controlled medicines, so their identity and purity can differ from the label. Such products may also contain unlisted compounds, which complicates both testing and safety assessment.
Scientific discussion of SR9009 often separates animal evidence from human anecdote. Rodent studies provide controlled data on endurance, metabolism, and gene expression, but they use specific strains, doses, and treatment durations. Human reports are mostly uncontrolled and cannot establish cause and effect. Open questions include oral bioavailability, tissue distribution, metabolic stability, and long-term effects. Review articles generally call for more rigorous pharmacokinetic and safety research before any clinical use could be considered.
Detection of SR9009 in biological samples usually relies on liquid chromatography coupled to tandem mass spectrometry. This approach separates the compound from matrix components and identifies it by mass transitions. Because SR9009 can undergo metabolism, laboratories often look for both parent drug and specific metabolites. Sample preparation may involve protein precipitation or solid-phase extraction. Method validation examines sensitivity, carryover, and interference from related substances, and reference standards are required for accurate calibration.
Storage recommendations for SR9009 reference material typically specify a freezer at -20 °C or lower, with protection from moisture and light. Repeated freeze-thaw cycles can degrade small molecules and introduce variability. Stock solutions in dimethyl sulfoxide are often aliquoted to avoid repeated handling. Stability studies may examine degradation under heat, humidity, and light exposure. The compound's thiophene and nitro groups can participate in reactions that alter analytical signals over time, so such changes affect quantitative results.
Quality control for research materials includes identity confirmation by nuclear magnetic resonance and purity assessment by high-performance liquid chromatography. Mass spectrometry provides molecular weight confirmation and can detect related impurities. Purchasers should request a certificate of analysis that lists lot-specific data. Online products advertised for human use often lack such documentation. Distinguishing legitimate research material from mislabeled or contaminated samples is a recurring challenge in independent testing, and independent laboratories may use orthogonal methods to verify identity.
REV-ERB proteins typically suppress gene expression by recruiting corepressor complexes to DNA response elements. SR9009 binds these receptors and strengthens that repressive action in cell-based assays. Studies in rodents have reported changes in lipid handling, mitochondrial function, and exercise capacity after treatment. Such findings are often cited as evidence for metabolic effects, but species differences and limited pharmacokinetic data make direct translation to humans uncertain. Researchers continue to examine which effects are robust and which depend on specific experimental conditions.
SR9009 is frequently discussed alongside other REV-ERB ligands, including synthetic agonists and natural heme-related molecules. Its selectivity for REV-ERB over related nuclear receptors has been measured in binding and reporter assays, though off-target activity at higher concentrations is possible. The compound is prohibited in sport by the World Anti-Doping Agency, and it is not approved for any medical use in major jurisdictions. Products sold online may be labeled as research chemicals, and their identity and purity are not guaranteed by regulatory review.
In 1979 Zaffaroni was awarded the Chemical Pioneer Award by the American Institute of Chemists In 1995, he received the National Medal of Technology from President Bill Clinton for his contributions to the pharmaceutical and biotechnology industries. In 2004, he was one of the recipients of the Winthrop-Sears Medal from the Chemical Heritage Foundation and The Chemists’ Club, with George Rosenkranz. In 2005 he received the Bower Award for Business Leadership from the Franklin Institute for his creation of new biochemical processes and drug delivery technologies. In 2005 he was awarded the Gregory Pincus Award from the Worcester Foundation. In 2006, he received the Biotechnology Heritage Award, from the Biotechnology Industry Organization (BIO) and the Chemical Heritage Foundation.
Immunomodulating agents regulate the immune system's response and are produced by various immune cells. These agents include the following agents and markers: The BCG vaccine has been used against tuberculosis, mycobacteria, and various cancers in the form of vaccination as an initial immune system stimulant. In cancer, the anti-tumor immunological effects are elicited by the host's immune response and the BCG infection against the tumor cells, most commonly in bladder cancer. The immune activation allows for further recognition and elimination of malignant tumor cells. Specific active immunotherapy administers a specific antigen as the therapy. The therapy allows the host to create an antigen-specific response with the development of antibodies, proliferation of cytotoxic T lymphocyte responses, or both, directed at the desired pathogen or malignant tumor cell in the case of cancer therapy.
Lab Matters: Each issue of APHL's quarterly magazine, Lab Matters, considers a pressing health issue of importance to public health laboratories. Bridges: Connecting the nation's environmental laboratories, Bridges is APHL's semi-annual newsletter for environmental health professionals. Social Media: APHL is active on Twitter, Facebook and LinkedIn, and has video channels on both YouTube and Vimeo. Blog: APHL's Public Health LabLog features recent and interesting stories about the work of APHL and public health laboratories. 1899: American Public Health Association formed the Committee of Laboratories 1921: Southern Public Health Laboratory Association (SPHLA) formed 1927: SPHLA became State Laboratory Directors Conference and opened membership to other states 1939: SPHLA changed its name to Conference of State and Provincial Laboratory Directors 1951: Association of State and Territorial Public Health Laboratory Directors founded 1998: Renamed the Association of Public Health Laboratories (APHL) and became a more inclusive organization with new membership categories
Sources: en.wikipedia.org
ACTA2 (actin alpha 2) is an actin protein with several aliases including alpha-actin, alpha-actin-2, aortic smooth muscle or alpha smooth muscle actin (α-SMA, SMactin, alpha-SM-actin, ASMA). Actins are a family of globular multi-functional proteins that form microfilaments. ACTA2 is one of six different actin isoforms and is involved in the contractile apparatus of smooth muscle. ACTA2 (as with all the actins) is extremely highly conserved and found in nearly all mammals. In humans, ACTA2 is encoded by the ACTA2 gene located on 10q22-q24. Mutations in this gene cause a variety of vascular diseases, such as thoracic aortic disease, coronary artery disease, stroke, Moyamoya disease, and multisystemic smooth muscle dysfunction syndrome. ACTA2 (commonly referred to as alpha-smooth muscle actin or α-SMA) is often used as a marker of myofibroblast formation. Studies have shown that ACTA2 is associated with TGF-β pathway that enhances contractile properties of hepatic stellate cells leading to liver fibrosis and cirrhosis.
Alfred Ellis Wilhelmi (1910–1994) was an American endocrinologist recognized for contributing to the understanding of anterior pituitary hormones. Born in Lakewood, Ohio, Wilhelmi attended Cleveland public schools. Wilhelmi earned a B.S. degree in premedical sciences from Western Reserve University in 1933. He then attended Oxford University as a Rhodes Scholar, where he obtained a B.A. in 1933 and Ph.D. in animal physiology in 1937. He then joined Yale University's Biochemistry Department, rising to the position of Professor in 1950. Wilhelmi chaired the Department of Biochemistry at Emory University School of Medicine from 1950 to 1977. In 1960, he was named Charles Howard Candler Professor of Biochemistry. In 1979, he received Emory's Thomas Jefferson award for service to the university and community. Wilhelmi also was President of the Endocrine Society from 1968 to 1969. During his career, he published over 80 articles in scientific journals.
GPCRs become desensitized when exposed to their ligand for a long period of time. There are two recognized forms of desensitization: 1) homologous desensitization, in which the activated GPCR is downregulated; and 2) heterologous desensitization, wherein the activated GPCR causes downregulation of a different GPCR. The key reaction of this downregulation is the phosphorylation of the intracellular (or cytoplasmic) receptor domain by protein kinases. Cyclic AMP-dependent protein kinases (protein kinase A) are activated by the signal chain coming from the G protein (that was activated by the receptor) via adenylate cyclase and cyclic AMP (cAMP). In a feedback mechanism, these activated kinases phosphorylate the receptor. The longer the receptor remains active the more kinases are activated and the more receptors are phosphorylated. In β2-adrenoceptors, this phosphorylation results in the switching of the coupling from the Gs class of G-protein to the Gi class. cAMP-dependent PKA mediated phosphorylation can cause heterologous desensitisation in receptors other than those activated.
Afamelanotide, sold under the brand name Scenesse, is a medication used to prevent phototoxicity and to reduce pain from light exposure for people with erythropoietic protoporphyria, a rare form of genetic sun sensitivity. Afamelanotide is a melanocortin 1 receptor (MC1 receptor) agonist and a synthetic peptide and analogue of α-melanocyte stimulating hormone. It is administered as subcutaneous implant. In the European Union, afamelanotide is indicated for the prevention of phototoxicity in adults with erythropoietic protoporphyria. In the United States, afamelanotide is indicated for increasing pain-free light exposure in adults with a history of reactions to light (phototoxicity) from erythropoietic protoporphyria.
Sources: en.wikipedia.org
Seven genes encode seven distinct 14-3-3 proteins in most mammals (See Human genes below) and 13–15 genes in many higher plants, though typically in fungi they are present only in pairs. Protists have at least one. Eukaryotes can tolerate the loss of a single 14-3-3 gene if multiple genes are expressed, but deletion of all 14-3-3s (as experimentally determined in yeast) results in death. 14-3-3 proteins are structurally similar to the Tetratrico Peptide Repeat (TPR) superfamily, which generally have 9 or 10 alpha helices, and usually form homo- and/or hetero-dimer interactions along their amino-termini helices. These proteins contain a number of known common modification domains, including regions for divalent cation interaction, phosphorylation & acetylation, and proteolytic cleavage, among others established and predicted. 14-3-3 binds to peptides. There are common recognition motifs for 14-3-3 proteins that contain a phosphorylated serine or threonine residue, although binding to non-phosphorylated ligands has also been reported. This interaction occurs along a so-called binding groove or cleft that is amphipathic in nature. To date, the crystal structures of six classes of these proteins have been resolved and deposited in the public domain.
AM function can be compared to another peptide called pro-adrenomedullin N-terminal 20 peptide (PAMP), which both originate from a common precursor leading to angiogenesis, vasodilation, and anti-inflammatory processes. These two peptides are expressed in the gastrointestinal (GI) tract at a mass level, serving as GI hormones controlling processes like insulin secretion and gastric emptying. Past studies reveal that AM and PAMP also impact gut microbiome composition by fostering the development of beneficial bacteria (i.e., Bifidobacterium and Lactobacillus) and diminishing detrimental microbes.
Primary structure Elzinga and co-workers first determined the complete peptide sequence for this type of actin in 1973, with later work by the same author adding further detail to the model. It contains 374 amino acid residues. Its N-terminus is highly acidic and starts with an acetyled aspartate in its amino group, while its C-terminus is alkaline and is formed by a phenylalanine preceded by a cysteine, which has a degree of functional importance. Both extremes are in close proximity within the I-subdomain. An anomalous Nτ-methylhistidine is located at position 73.
Sources: en.wikipedia.org
It is a synthetic compound that acts as an agonist at REV-ERBα and REV-ERBβ. It is used mainly as a research chemical to study circadian and metabolic pathways. It is not approved for human therapeutic use.
REV-ERB receptors generally repress transcription when bound by natural heme. SR9009 is described as an agonist that enhances this repressive activity. The result is altered expression of clock and metabolic genes.
Published controlled human trials are lacking. Some sources cite limited or unofficial reports, but these do not establish safety or efficacy. Claims about human performance effects remain unverified.
It is a synthetic research compound that activates REV-ERB nuclear receptors. It is not an approved drug or dietary supplement. Most information comes from cell and animal studies.