GO:0051786 all-trans-retinol 13,14-reductase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0051786 all-trans-retinol 13,14-reductase activity catalyzes the saturation of the 13,14 double bond of all-trans-retinol to produce all-trans-13,14-dihydroretinol, a reaction observed in the reverse direction in vivo.
• The enzyme responsible, retinol saturase (RetSat), is a microsomal protein conserved from bacteria to humans and is highly expressed in liver, adipose tissue, and intestine [1,3,4].
• RetSat activity influences adipogenesis, lipid metabolism, and insulin sensitivity, with knockout mice showing increased adiposity and altered hepatic gene expression [5,6].
• RetSat coordinates liver metabolism by regulating ChREBP activity, linking retinol saturation to carbohydrate and lipid homeostasis.
• Intestinal RetSat is implicated in obesity development and epithelial homeostasis upon injury, suggesting tissue-specific roles.
• Studying GO:0051786 requires combining enzymatic assays, lipidomics, and CRISPR-based models to dissect its physiological functions [1,2].
Description
GO:0051786 all-trans-retinol 13,14-reductase activity is a molecular function that catalyzes the reduction of the 13,14 double bond of all-trans-retinol to yield all-trans-13,14-dihydroretinol. This enzymatic activity is carried out by retinol saturase (RetSat), a protein that has attracted attention because of its roles in lipid metabolism, adipogenesis, and metabolic disease [1,6]. The reaction is unusual because it has only been observed to occur in the opposite direction in vivo, meaning that the enzyme primarily saturates retinol rather than desaturating dihydroretinol. Researchers study this activity to understand how retinoid metabolism intersects with energy balance and cellular differentiation [2,5]. The importance of GO:0051786 extends beyond basic enzymology; RetSat expression is regulated by peroxisome proliferator-activated receptor alpha (PPARα) and is induced by starvation, linking it to fasting responses and fatty acid oxidation. Moreover, RetSat knockout mice display increased adiposity and altered expression of metabolic genes, underscoring its physiological relevance. In this article, we provide a comprehensive overview of the mechanism, genes, and research methods associated with GO:0051786, based on authoritative QuickGO data and verified PubMed literature.
all-trans-retinol 13,14-reductase activity At A Glance
| GO ID | GO:0051786 |
|---|---|
| GO term | all-trans-retinol 13,14-reductase activity |
| Ontology | molecular_function |
| Synonym | retinol saturase activity; RetSat activity; all-trans-retinol:all-trans-13,14-dihydroretinol saturase activity |
| Major function | Catalyzes the saturation of the 13,14 double bond of all-trans-retinol to produce all-trans-13,14-dihydroretinol |
| Reaction direction | Observed only in the reverse direction in vivo (reduction of retinol) |
| Cofactor | Acceptor (A) required; likely uses NAD(P)H or other electron acceptors |
| Subcellular location | Microsomal membrane (endoplasmic reticulum) |
| Related gene | RETSAT (retinol saturase) |
What Is GO:0051786?
According to the Gene Ontology, GO:0051786 all-trans-retinol 13,14-reductase activity is defined as the catalysis of the reaction: all-trans-13,14-dihydroretinol + A = all-trans-retinol + AH(2). The reaction has only been observed to occur in the opposite direction, meaning that the enzyme typically reduces all-trans-retinol to all-trans-13,14-dihydroretinol using an acceptor. Synonyms include retinol saturase activity, RetSat activity, and all-trans-retinol:all-trans-13,14-dihydroretinol saturase activity. This activity is a molecular function that contributes to retinoid metabolic processes and is encoded by the RETSAT gene in humans.
Why Is all-trans-retinol 13,14-reductase activity Important in Cell Biology?
GO:0051786 all-trans-retinol 13,14-reductase activity is important because it represents a key enzymatic step in retinoid metabolism that influences fundamental processes such as adipogenesis, lipid homeostasis, and energy balance [1,6]. RetSat, the enzyme responsible for this activity, is regulated by PPARα and is induced by starvation, positioning it at the intersection of fasting responses and lipid metabolism. Genetic deletion of RetSat in mice leads to increased adiposity and altered expression of genes involved in fatty acid oxidation and lipogenesis, highlighting its role in whole-body metabolism. Furthermore, RetSat coordinates liver metabolism by modulating ChREBP activity, a transcription factor critical for lipogenesis. In the intestine, RetSat is implicated in obesity development and epithelial homeostasis upon injury, suggesting tissue-specific functions. Thus, understanding GO:0051786 is essential for researchers studying metabolic disorders, obesity, and retinoid biology.
• Regulates adipogenesis and lipid accumulation, with RetSat knockout mice showing increased adiposity.
• Modulates hepatic carbohydrate and lipid metabolism through ChREBP regulation.
• Is induced by starvation and PPARα activation, linking it to fasting adaptation.
• Plays a role in intestinal epithelial homeostasis and obesity development.
• Influences retinol signaling pathways in pluripotent cells, affecting differentiation.
• Downregulated in obesity, suggesting a protective role against metabolic dysfunction.
• Provides a potential target for therapeutic intervention in metabolic diseases.
• Serves as a model for studying enzyme reactions that occur predominantly in reverse.
What Happens During all-trans-retinol 13,14-reductase activity?
Substrate Binding and Acceptor Interaction
In simple terms: The enzyme grabs retinol and an acceptor molecule to start the reaction.
The enzymatic reaction begins with the binding of all-trans-retinol and an electron acceptor (A) to the active site of retinol saturase (RetSat). The acceptor is likely a pyridine nucleotide or another redox cofactor, although the exact identity in vivo remains to be fully characterized. The binding is facilitated by the microsomal membrane environment, where RetSat is anchored.
Catalytic Saturation of the 13,14 Double Bond
In simple terms: The enzyme adds hydrogens to a specific double bond in retinol, converting it to dihydroretinol.
RetSat catalyzes the saturation of the 13,14 double bond of all-trans-retinol, yielding all-trans-13,14-dihydroretinol. This reaction is unusual because it has only been observed to occur in the opposite direction in vivo, meaning that the enzyme primarily reduces retinol rather than oxidizing dihydroretinol. The catalytic mechanism likely involves hydride transfer from the acceptor to the substrate, although detailed structural studies are needed.
Product Release and Metabolic Fate
In simple terms: After the reaction, the new molecule is released and can be used in other pathways.
Following catalysis, all-trans-13,14-dihydroretinol is released from the enzyme and can participate in downstream metabolic pathways. This product may serve as a signaling molecule or be further metabolized, although its exact fate is not fully understood. The reaction is thought to modulate retinol availability for other retinoid-dependent processes.
Tissue-Specific Variations
In simple terms: Different tissues may perform this reaction differently depending on their needs.
RetSat is expressed in various tissues, including liver, adipose tissue, and intestine, where its activity may be regulated differently [3,4]. In the liver, RetSat activity is linked to ChREBP regulation and lipogenesis. In the intestine, it influences epithelial homeostasis and obesity development. These tissue-specific roles suggest that the reaction may be fine-tuned to local metabolic demands.
Key Genes Involved in GO:0051786 all-trans-retinol 13,14-reductase activity
The following genes and proteins are directly or indirectly associated with GO:0051786 all-trans-retinol 13,14-reductase activity, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| RETSAT | Encodes retinol saturase, the enzyme responsible for GO:0051786 activity | Central to studying the reaction mechanism and metabolic functions |
| PPARA | Nuclear receptor that regulates RETSAT expression | Links RetSat to fatty acid oxidation and starvation response |
| CHREBP | Transcription factor regulated by RetSat in liver | Mediates RetSat effects on lipogenesis and glucose metabolism |
| P19 | Pluripotent cell line used to study retinol signaling | Model for differentiation and retinoid metabolism |
| ADIPOG | Adiponectin, involved in adipocyte function | May be affected by RetSat activity in adipose tissue |
| FASN | Fatty acid synthase, key lipogenic enzyme | Expression may be influenced by RetSat via ChREBP |
| SCD1 | Stearoyl-CoA desaturase 1, involved in lipid synthesis | Potential downstream target of RetSat in liver |
| CPT1A | Carnitine palmitoyltransferase 1A, rate-limiting for fatty acid oxidation | May be regulated by PPARα and RetSat |
| UCP1 | Uncoupling protein 1, thermogenesis marker | Could be affected by RetSat in adipose tissue |
| LEP | Leptin, adipokine regulating energy balance | May be altered in RetSat knockout mice |
| IL6 | Interleukin 6, inflammatory cytokine | Potential link between RetSat and inflammation in obesity |
| TNF | Tumor necrosis factor, inflammatory cytokine | May be modulated by RetSat in metabolic tissues |
| SREBF1 | Sterol regulatory element-binding transcription factor 1 | Lipogenic transcription factor potentially downstream of RetSat |
| NR1H3 | Liver X receptor alpha, regulates lipid metabolism | May interact with RetSat pathways |
| RXRA | Retinoid X receptor alpha, partner for PPARα | Involved in RetSat regulation via PPARα |
| PPARGC1A | PGC-1α, coactivator of PPARα | May influence RETSAT expression during fasting |
How Is all-trans-retinol 13,14-reductase activity Regulated?
RETSAT expression is regulated by the nuclear receptor PPARα, which is activated during fasting and by fibrates. The promoter of RETSAT contains a PPAR response element, allowing PPARα to directly induce its transcription. Additionally, RetSat activity may be modulated by substrate availability and the redox state of the cell, as the reaction requires an electron acceptor. In obesity, RETSAT expression is downregulated, suggesting that metabolic status influences its regulation. Furthermore, RetSat coordinates liver metabolism by regulating ChREBP activity, which in turn affects lipogenic gene expression. This feedback loop highlights the intricate regulation of GO:0051786 in response to nutritional and hormonal signals.
all-trans-retinol 13,14-reductase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| RETSAT | Obesity and metabolic syndrome | RetSat knockout mouse |
| RETSAT | NAFLD and hepatic steatosis | Liver-specific RetSat knockout |
| RETSAT | Intestinal inflammation | Intestinal epithelial cell-specific knockout |
| PPARA | Dyslipidemia and fatty acid oxidation disorders | PPARα knockout mouse |
| CHREBP | Lipogenesis and glucose intolerance | ChREBP knockout mouse |
Obesity and Metabolic Syndrome
RetSat knockout mice exhibit increased adiposity and altered expression of metabolic genes, indicating a role in obesity. In humans, RETSAT expression is downregulated in obesity, and its intestinal levels are implicated in obesity development [4,6]. These findings suggest that GO:0051786 activity may protect against excessive fat accumulation.
Type 2 Diabetes and Insulin Resistance
RetSat influences glucose metabolism through ChREBP regulation in the liver. Dysregulation of this pathway could contribute to insulin resistance and type 2 diabetes. However, direct evidence linking GO:0051786 to diabetes in humans is still emerging.
Non-Alcoholic Fatty Liver Disease (NAFLD)
RetSat coordinates hepatic lipid metabolism by modulating ChREBP, and its dysregulation may promote steatosis. Further studies are needed to establish whether GO:0051786 activity is protective or detrimental in NAFLD.
Intestinal Inflammation and Homeostasis
Intestinal RetSat is involved in epithelial homeostasis upon injury, and its loss may exacerbate inflammation. This suggests a potential role for GO:0051786 in inflammatory bowel diseases, though more research is required.
From all-trans-retinol 13,14-reductase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the enzymatic mechanism of RetSat? | Recombinant RetSat protein with point mutations in active site |
| How does RetSat affect adiposity? | RetSat knockout mouse |
| What is the role of RetSat in liver metabolism? | Liver-specific RetSat knockout or overexpression |
| How does RetSat influence intestinal homeostasis? | Intestinal epithelial-specific knockout |
| Does RetSat regulate ChREBP activity? | Knock-in of RetSat mutants or overexpression |
| What is the impact of RetSat on retinol signaling? | P19 cells with RetSat knockout or overexpression |
How to Study the all-trans-retinol 13,14-reductase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Enzymatic assay with LC-MS | RetSat catalytic activity | Kinetic studies and inhibitor screening |
| Lipidomics | Retinoid and lipid metabolite levels | Profiling metabolic changes in cells/tissues |
| RNA-seq | Gene expression changes | Identifying downstream targets of RetSat |
| CRISPR knockout screens | Genes affecting RetSat pathway | Discovery of novel regulators |
| Western blot | RetSat protein levels | Validating expression in models |
| Immunofluorescence | Subcellular localization of RetSat | Confirming microsomal localization |
| Co-immunoprecipitation | Protein-protein interactions | Finding RetSat binding partners |
| Metabolic flux analysis | Flux through retinoid pathway | Quantifying RetSat contribution to metabolism |
Enzymatic Assays for RetSat Activity
Direct measurement of GO:0051786 activity can be performed using microsomal fractions from cells or tissues, incubated with all-trans-retinol and an electron acceptor, followed by HPLC or LC-MS analysis of the product all-trans-13,14-dihydroretinol. This method is essential for validating enzyme kinetics and substrate specificity.
Lipidomics and Retinoid Profiling
Mass spectrometry-based lipidomics allows comprehensive profiling of retinoids and their metabolites in biological samples, providing insights into the metabolic flux through GO:0051786. This approach can identify changes in retinol and dihydroretinol levels in response to genetic or environmental perturbations.
Transcriptomics and Gene Expression Analysis
RNA-seq can reveal how RETSAT expression and its downstream targets are regulated under different conditions, such as fasting or PPARα activation. This method helps identify co-regulated genes and pathways associated with GO:0051786.
CRISPR-Based Genetic Screens
Genome-wide CRISPR knockout screens can identify genes that modulate RetSat activity or its metabolic effects, uncovering novel regulators and potential therapeutic targets. Such screens are powerful for dissecting complex metabolic pathways.
How CRISPR Can Be Used to Study GO:0051786 all-trans-retinol 13,14-reductase activity
Knockout
CRISPR-Cas9 knockout of RETSAT in cell lines or animal models abolishes GO:0051786 activity, allowing researchers to study its loss-of-function phenotypes, such as increased adiposity in mice. Knockout models are essential for understanding the physiological roles of RetSat.
Point Mutation
Introducing point mutations in the catalytic domain of RETSAT can dissect the enzymatic mechanism and separate catalytic activity from other functions. Such models help identify critical residues for substrate binding and catalysis.
Knock-in
Knock-in of tagged or fluorescently labeled RETSAT allows real-time tracking of the enzyme's localization and dynamics in live cells. This approach can reveal how RetSat traffics and interacts with other proteins.
Overexpression
Overexpression of RETSAT in cell lines or tissues can amplify GO:0051786 activity, enabling studies of its downstream effects on lipid metabolism and gene expression. This is useful for gain-of-function experiments.
How EDITGENE Supports all-trans-retinol 13,14-reductase activity Research
Researchers studying all-trans-retinol 13,14-reductase activity-related genes often need to determine whether a candidate gene is causally involved in metabolic phenotypes or whether its manipulation alters retinoid signaling. EDITGENE provides a comprehensive suite of CRISPR-based services to accelerate such investigations, from gene knockout to precise point mutations and library screening.
Contact EDITGENE today to design your custom CRISPR model for all-trans-retinol 13,14-reductase activity research.
Frequently Asked Questions About all-trans-retinol 13,14-reductase activity
What is GO:0051786 all-trans-retinol 13,14-reductase activity?
It is a molecular function that catalyzes the saturation of the 13,14 double bond of all-trans-retinol to produce all-trans-13,14-dihydroretinol, primarily observed in the reverse direction.
What gene encodes all-trans-retinol 13,14-reductase activity?
The RETSAT gene encodes retinol saturase, the enzyme responsible for this activity.
What is the function of retinol saturase (RetSat)?
RetSat catalyzes GO:0051786 and plays roles in adipogenesis, lipid metabolism, and liver function [1,6].
How is all-trans-retinol 13,14-reductase activity regulated?
RETSAT expression is regulated by PPARα and is induced by starvation; activity may also depend on substrate availability.
What diseases are associated with all-trans-retinol 13,14-reductase activity?
It has been linked to obesity, metabolic syndrome, and fatty liver disease [3,5].
What are the substrates of all-trans-retinol 13,14-reductase?
The substrate is all-trans-retinol, and the product is all-trans-13,14-dihydroretinol.
What is the reaction catalyzed by GO:0051786?
The reaction is: all-trans-13,14-dihydroretinol + A = all-trans-retinol + AH(2), but it is observed in the reverse direction in vivo.
Which tissues express retinol saturase?
RetSat is highly expressed in liver, adipose tissue, and intestine [3,4].
How can I study all-trans-retinol 13,14-reductase activity in the lab?
You can use enzymatic assays, lipidomics, and CRISPR-based knockout or overexpression models [1,5].
What are the synonyms for all-trans-retinol 13,14-reductase activity?
Synonyms include retinol saturase activity, RetSat activity, and all-trans-retinol:all-trans-13,14-dihydroretinol saturase activity.
Conclusion
GO:0051786 all-trans-retinol 13,14-reductase activity is a unique enzymatic function that bridges retinoid metabolism and energy homeostasis. Through its product all-trans-13,14-dihydroretinol, it influences adipogenesis, lipid metabolism, and liver function, with implications for obesity and metabolic diseases [1,3,5]. The enzyme RetSat is regulated by PPARα and coordinates ChREBP activity, highlighting its integration into fasting and lipogenic pathways [3,8]. Continued research using CRISPR models and advanced lipidomics will further elucidate its physiological roles and therapeutic potential. EDITGENE provides the tools to accelerate such discoveries.
References
- 1. Weber P et al.. 2020. Retinol Saturase: More than the Name Suggests.. Trends Pharmacol Sci 41(6):418-427 PMID: 32345479
- 2. Chen Y et al.. 2011. The retinol signaling pathway in mouse pluripotent P19 cells.. J Cell Biochem 112(10):2865-72 PMID: 21618588
- 3. Heidenreich S et al.. 2017. Retinol saturase coordinates liver metabolism by regulating ChREBP activity.. Nat Commun 8(1):384 PMID: 28855500
- 4. Kiefer MF et al.. 2024. Intestinal retinol saturase is implicated in the development of obesity and epithelial homeostasis upon injury.. Am J Physiol Endocrinol Metab 327(2):E203-E216 PMID: 38895981
- 5. Moise AR et al.. 2010. Increased adiposity in the retinol saturase-knockout mouse.. FASEB J 24(4):1261-70 PMID: 19940255
- 6. Schupp M et al.. 2009. Retinol saturase promotes adipogenesis and is downregulated in obesity.. Proc Natl Acad Sci U S A 106(4):1105-10 PMID: 19139408
- 8. Sun Y et al.. 2008. Identification and characterization of a novel mouse peroxisome proliferator-activated receptor alpha-regulated and starvation-induced gene, Ppsig.. Int J Biochem Cell Biol 40(9):1775-91 PMID: 18289917
