Fat Production Breakthrough: Discovery of Crucial Enzyme That Blocks Weight Gain When Inhibited

🔬 The Discovery of SCoR2: A Game-Changer in Fat Regulation

In late 2025, researchers at University Hospitals and Case Western Reserve University unveiled a pivotal scientific advancement in the battle against obesity. They identified a previously unknown enzyme called SCoR2, or S-nitrosocysteine reductase 2, which plays a central role in fat production. This enzyme acts as a protein denitrosylase, removing nitric oxide—a key signaling molecule—from proteins that govern lipid synthesis and storage. When SCoR2 is active, it essentially flips a switch that promotes the buildup of fat in the body. Remarkably, inhibiting this enzyme not only halts new fat formation but also helps lower harmful cholesterol levels and protects the liver from damage.

The study, published on December 23, 2025, in Science Signaling, demonstrated that blocking SCoR2 in mouse models fed high-fat diets completely prevented weight gain. These mice maintained healthy body weights, showed reduced low-density lipoprotein (LDL) cholesterol—the 'bad' kind linked to heart disease—and avoided liver injury associated with metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as non-alcoholic fatty liver disease. Lead researcher Jonathan Stamler, MD, a distinguished professor of medicine and biochemistry, described it as 'a new class of drug that prevents weight gain and lowers cholesterol—a potential therapy for obesity and cardiovascular disease, with additional hepatic benefits.'

This breakthrough addresses a core issue in obesity: de novo lipogenesis, or the body's process of creating new fats from non-fat sources like carbohydrates. Unlike appetite-suppressing drugs, SCoR2 inhibitors target fat production at its molecular root, offering a complementary approach to weight management.

Demystifying Fat Production: From Basics to Biochemical Pathways

To grasp the significance of SCoR2, it's essential to understand how the body produces and stores fat. Fat, or lipids, serves as an energy reserve, insulation, and structural component for cells. When we consume more calories than needed, especially from sugars and starches, the liver converts excess into triglycerides via de novo lipogenesis (DNL). This process involves key enzymes like acetyl-CoA carboxylase (ACC) and fatty acid synthase (FASN), which build fatty acid chains from smaller molecules.

Adipocytes, or fat cells, store these triglycerides in white adipose tissue, which expands during overeating, leading to weight gain. In contrast, brown adipose tissue burns fat for heat. Obesity arises when energy intake chronically exceeds expenditure, tipping the balance toward storage. Worldwide, obesity affects over 1 billion people, per World Health Organization data from 2024, raising risks for type 2 diabetes, heart disease, and certain cancers.

• Excess carbohydrates stimulate insulin release, activating DNL in the liver.
• Lipogenic transcription factors like PPARγ (peroxisome proliferator-activated receptor gamma), SREBP1 (sterol regulatory element-binding protein 1), and CEBPα (CCAAT/enhancer-binding protein alpha) drive enzyme production.
• Cholesterol synthesis parallels fat production, contributing to dyslipidemia.

Nitric oxide (NO), produced by nitric oxide synthase enzymes, modulates these pathways through S-nitrosylation—a reversible modification where NO attaches to cysteine residues on proteins, inhibiting their activity. SCoR2 counteracts this by denitrosylating proteins, reactivating fat-making machinery.

How SCoR2 Functions: The Nitric Oxide 'Fat Switch'

SCoR2's mechanism is elegantly simple yet profoundly impactful. In the liver, NO S-nitrosylates enzymes involved in fat and cholesterol synthesis, keeping them dormant. SCoR2 removes NO, allowing these enzymes to function and produce lipids. Similarly, in adipose tissue, NO suppresses the genetic programs (via transcription factors) that expand fat cells; denitrosylation by SCoR2 enables adipocyte hypertrophy.

Experiments revealed that SCoR2 abundance correlates with body mass in mice and humans. An obesity-linked genetic polymorphism increases SCoR2 mRNA expression, linking it directly to fat accumulation. In adipocytes, inhibiting SCoR2 leads to persistent S-nitrosylation of myosin 9, a cytoskeletal protein that normally supports lipogenic transcription factors. This inhibition shrinks fat cells. In hepatocytes (liver cells), it boosts fatty acid oxidation—the burning of fats for energy—reducing steatosis.

Pharmacologically, the team developed a small-molecule inhibitor that mimics genetic knockout effects. Mice treated with it on high-fat diets showed no weight gain over weeks, contrasting with controls that gained 20-30% body weight. Liver fat content dropped significantly, and plasma LDL fell by up to 40%.

Study Details: Rigorous Evidence from Mouse Models

The research employed sophisticated genetic and pharmacological approaches. Researchers used CRISPR-Cas9 to knock out SCoR2 in mice, confirming its necessity for diet-induced obesity. High-fat diet (HFD) mice lacking SCoR2 resisted weight gain, maintained insulin sensitivity, and avoided MASLD hallmarks like inflammation and fibrosis.

Pharmacological validation involved an orally bioavailable inhibitor screened from compound libraries. Chronic dosing prevented hepatic lipogenesis, upregulated beta-oxidation genes, and normalized lipid profiles. Human relevance was shown through tissue analysis: SCoR2 levels in obese patients' adipose and liver correlated with adipocyte size and steatosis severity.

Funding from the Harrington Discovery Institute supported drug optimization. No major side effects were noted in preclinical models, unlike some ACC inhibitors that caused liver toxicity in past trials. For deeper insights, the full study is available in Science Signaling.

• Genetic KO: 100% prevention of HFD weight gain.
• Drug treatment: Reduced body fat by 25-35%, preserved lean mass.
• Human data: SCoR2 mRNA up 2-fold in obese cohorts.

Revolutionary Treatment Potential: Beyond Current Options

Current obesity drugs like semaglutide (Ozempic) or tirzepatide (Mounjaro)—GLP-1 receptor agonists—excel at curbing appetite and promoting modest weight loss (15-20% body weight). However, they often lead to muscle loss, gastrointestinal side effects, and weight regain upon cessation. SCoR2 inhibitors promise targeted fat reduction without appetite suppression, preserving muscle and addressing comorbidities like hypercholesterolemia and MASLD simultaneously.

A 'three-in-one' drug is in development, potentially entering phase 1 trials by mid-2027. Early data suggest synergy with existing therapies. For details on the initial findings, see the University Hospitals release.

In higher education, such discoveries fuel demand for experts in metabolic research. Aspiring scientists can explore research jobs advancing these frontiers.

Broader Implications for Public Health and Research

Obesity's global cost exceeds $2 trillion annually, per recent estimates. SCoR2 inhibition could transform management, especially for the 40% of U.S. adults with obesity. It highlights nitric oxide signaling's untapped therapeutic potential, akin to sirtuins in aging research.

Challenges remain: human translation, long-term safety, and off-target effects. Ongoing studies probe SCoR2 in other tissues. Academic institutions drive this progress; professors in biochemistry often lead such teams. Share experiences with faculty via Rate My Professor.

More at postdoctoral success guide.

Photo by Jakub Żerdzicki on Unsplash

Looking Ahead: From Bench to Bedside

With clinical trials on the horizon, SCoR2 represents hope for sustainable weight control. Researchers emphasize balanced lifestyles alongside pharmacotherapy. For careers in this dynamic field, check higher ed jobs in pharmacology and nutrition sciences.

In summary, this fat production breakthrough underscores precision medicine's power. Explore professor insights on Rate My Professor, pursue higher ed jobs, or advance your career via higher ed career advice and university jobs. Post your thoughts below!