# NR1D1 Gene: Structure, Function, and Clinical Significance


## Key Takeaways

- NR1D1 (REV-ERBα) is a nuclear receptor that functions as a transcriptional repressor, playing a critical role in the molecular circadian clock by forming a negative feedback loop that stabilizes BMAL1 oscillations.
- The NR1D1 gene is located at 17q21.1 and its expression is regulated by E-box elements, Sp1 binding sites, and long-range enhancers, with alternative splicing generating functional isoforms.
- Structurally, NR1D1 possesses a DNA-binding domain (DBD) that recognizes RevRE elements and a ligand-binding domain (LBD) that uniquely binds heme as a cofactor, essential for recruiting corepressors like NCoR1 and HDAC3.
- NR1D1 integrates metabolic, inflammatory, and developmental signals, regulating lipid and glucose homeostasis, suppressing pro-inflammatory cytokines via NF-κB inhibition, and modulating autophagy and mitophagy.
- Dysregulation of NR1D1 is implicated in a spectrum of clinical conditions, including metabolic syndrome, neuropsychiatric disorders (e.g., bipolar disorder, MDD, ASD), cancer (context-dependent), and retinal diseases, with specific gene fusions identified in soft tissue tumors.
- NR1D1 is a druggable target, with synthetic agonists like GSK4112 and SR9009 showing therapeutic potential in metabolic, inflammatory, and oncological contexts, and its polymorphisms are being investigated for pharmacogenomic applications in mood disorder treatment.

---

## Executive Summary & Key Metadata

NR1D1 (Nuclear Receptor Subfamily 1, Group D, Member 1), commonly known as REV-ERBα, is a ligand-modulated transcription factor belonging to the nuclear receptor superfamily. Unlike classical nuclear receptors that activate transcription upon ligand binding, NR1D1 functions as a potent transcriptional repressor. It is a core component of the molecular circadian clock, where it forms a subsidiary negative feedback loop that stabilizes the primary CLOCK/BMAL1 oscillation. Beyond circadian rhythm generation, NR1D1 integrates metabolic, inflammatory, and developmental signals, positioning it as a critical node in the pathophysiology of metabolic syndrome, cancer, inflammatory diseases, and neuropsychiatric disorders. The gene is also a target of significant clinical interest due to its role in mediating the effects of environmental toxicants and its potential as a druggable target for chronotherapy.

| **Attribute** | **Detail** |
| :--- | :--- |
| **HGNC Symbol** | NR1D1 |
| **UniProt Accession** | P20393 |
| **Representative PDB ID** | 3N00 (LBD with heme), 5UD0 (DBD-DNA complex) |
| **Chromosomal Locus** | 17q21.1 (Human); GRCh38: chr17:40,008,000-40,016,000 (approximate) |
| **Primary Molecular Function** | Transcriptional repression; core circadian clock component; heme sensor; regulation of lipid and glucose metabolism; modulation of inflammatory response |
| **Disease & Pathology Associations** | Metabolic syndrome, type 2 diabetes, atherosclerosis, cancer (context-dependent tumor suppressor/oncogene), inflammatory bowel disease, asthma, neuropsychiatric disorders (bipolar disorder, major depressive disorder, autism spectrum disorder), retinitis pigmentosa, soft tissue sarcomas (gene fusions) |

## 1. Genomic Locus, Chromosomal Organization & Isoforms

### 1.1 Chromosomal Localization and Gene Structure

The human NR1D1 gene is located on the long arm of chromosome 17 at cytogenetic band 17q21.1. This locus is gene-dense and shares a complex, overlapping genomic architecture with the THRA (Thyroid Hormone Receptor Alpha) gene. The NR1D1 gene is situated on the opposite strand of THRA, and the two genes exhibit overlapping 3' untranslated regions (UTRs). This configuration is a classic example of a sense-antisense gene pair, where the 3' ends of the two genes overlap, potentially allowing for the generation of natural antisense transcripts that may play a role in post-transcriptional regulation [1]. The genomic span of NR1D1 is approximately 8 kilobases, containing 8 exons that are alternatively spliced to produce multiple transcript variants.

The core promoter of NR1D1 lacks a canonical TATA box but contains a high GC content and multiple binding sites for Sp1 (Specificity Protein 1), which is essential for basal transcription. The promoter region also contains functional response elements for the core circadian machinery, including E-box elements (CACGTG) recognized by the CLOCK:BMAL1 heterodimer. This E-box-mediated regulation is the primary driver of the robust circadian oscillation of NR1D1 mRNA, which peaks in the late afternoon/early evening in humans [2]. Additionally, the promoter contains response elements for the glucocorticoid receptor (GR), which has been shown to suppress NR1D1 expression through interaction with the CLOCK complex, providing a molecular link between stress hormones and circadian rhythm disruption [3].

### 1.2 Enhancer Elements and Chromatin Architecture

The expression of NR1D1 is not solely governed by its proximal promoter. Long-range chromatin interactions, mediated by the cohesin complex, bring distal enhancer elements into proximity with the NR1D1 promoter to regulate its circadian expression. Chromosome conformation capture (Hi-C) studies have demonstrated that the NR1D1 locus undergoes dynamic changes in chromatin looping that correlate with its transcriptional state [4]. These long-range interactions are critical for the precise temporal control of NR11D1 expression, and disruption of these interactions can lead to arrhythmic gene expression.

### 1.3 Alternative Splicing and Isoforms

Alternative splicing of the NR1D1 pre-mRNA gives rise to several transcript variants. The primary transcript encodes the canonical 614-amino acid protein. However, alternative splicing events, particularly in the 5' UTR and the region encoding the N-terminal domain, generate isoforms with altered N-termini. Some of these isoforms lack a portion of the N-terminal domain, which contains a ligand-independent activation function (AF-1) that is atypical for NR1D1, as it primarily acts as a repressor. The functional significance of these isoforms is an area of active investigation, but they may exhibit differential tissue-specific expression or altered interactions with corepressor complexes. In mice, a specific deletion of exons 3 and 4 has been shown to produce a truncated, non-functional protein, leading to a phenotype of exacerbated hepatic steatosis when challenged with a high-fat diet, highlighting the importance of these exons for protein function [5].

## 2. 3D Protein Domain Architecture & Structural Biology

The NR1D1 protein is a member of the nuclear receptor superfamily and shares the canonical modular architecture of this family, consisting of an N-terminal domain, a DNA-binding domain (DBD), a hinge region, and a ligand-binding domain (LBD). However, NR1D1 possesses unique structural features that distinguish it from classical nuclear receptors.

### 2.1 N-Terminal Domain (NTD) – Atypical AF-1

The N-terminal domain (residues 1–100) is the most variable region among nuclear receptors. For NR1D1, this domain is relatively short and does not contain a classical, strong ligand-independent activation function (AF-1). Instead, it is thought to contribute to the overall repression function by stabilizing the interaction with corepressor complexes. The NTD may also contain sites for post-translational modifications, such as phosphorylation, that modulate protein stability and transcriptional activity.

### 2.2 DNA-Binding Domain (DBD) – The Zinc Finger Module

The DBD (residues 100–170) is the most highly conserved region of the protein. It contains two C4-type zinc finger motifs that mediate sequence-specific DNA binding. The first zinc finger recognizes the major groove of the DNA double helix, while the second finger stabilizes the interaction and contributes to dimerization on DNA. NR1D1 binds as a monomer or a homodimer to a specific DNA sequence known as a Rev-erbA Response Element (RevRE). The consensus RevRE is a half-site of the canonical nuclear receptor response element, AGGTCA, preceded by an A/T-rich sequence (5'-A/T AGGTCA-3'). The DBD of NR1D1 can also bind to a direct repeat of the half-site spaced by two nucleotides (DR2), which is the preferred binding mode for homodimers. The structural details of the DBD-DNA interaction have been resolved by X-ray crystallography, revealing the precise contacts between the zinc-coordinating cysteines, the recognition helix, and the DNA backbone.

### 2.3 Hinge Region

The hinge region (residues 170–250) connects the DBD to the LBD. This region is flexible and contains a nuclear localization signal (NLS). It also plays a role in modulating DNA binding affinity and corepressor recruitment. The hinge region is a target for post-translational modifications, including SUMOylation, which can influence the transcriptional repressive activity of NR1D1.

### 2.4 Ligand-Binding Domain (LBD) – The Heme Sensor

The LBD (residues 250–614) is the largest domain and is responsible for ligand binding, dimerization, and interaction with corepressor complexes. The canonical structure of a nuclear receptor LBD consists of 12 alpha-helices (H1-H12) arranged in a three-layered antiparallel helical sandwich. The ligand-binding pocket is located in the lower half of the domain.

For NR1D1, the LBD has a unique feature: it binds heme as a prosthetic group. Heme is not a classical ligand that induces a conformational change to activate the receptor; rather, it is a required cofactor for the structural stability of the LBD and for the recruitment of corepressors. The iron atom of the heme group is coordinated by a cysteine residue (Cys384) and a histidine residue (His568). This coordination is essential for the repressive function of NR1D1. The binding of heme is reversible and is thought to be regulated by cellular redox state and nitric oxide (NO) levels. When heme is bound, NR1D1 adopts a conformation that has a high affinity for the nuclear receptor corepressor (NCoR) and histone deacetylase 3 (HDAC3). The heme-binding pocket is also the target for synthetic small-molecule agonists, such as GSK4112 and SR9009, which stabilize the active conformation and enhance corepressor recruitment.

The C-terminal helix H12, which in agonist-bound classical nuclear receptors forms a "lid" over the ligand-binding pocket and creates a surface for coactivator binding, is positioned differently in NR1D1. In the heme-bound state, H12 is folded back into the core of the LBD, creating a hydrophobic surface that is optimized for corepressor interaction. This unique conformation explains why NR1D1 functions almost exclusively as a repressor.

### 2.5 Interactive 3D Visualizer

To explore the three-dimensional structure of the NR1D1 protein, including its DBD and heme-bound LBD, use the interactive visualizer below. This tool allows for the manipulation of the protein structure, highlighting key domains, ligand-binding pockets, and mutation sites.

[Interactive 3D Protein Visualizer: Load NR1D1 (PDB: true)](/tools/protein-structure-viewer?source=alphafold&accession=P20393)

## 3. Cellular Signaling Pathways & Molecular Function

NR1D1 is a master regulator of gene expression, primarily functioning as a transcriptional repressor. Its activity is integrated into several key signaling pathways, most notably the circadian clock, metabolism, and inflammation.

### 3.1 The Circadian Clock: The Auxiliary Negative Feedback Loop

The molecular circadian clock is driven by a cell-autonomous transcription-translation feedback loop (TTFL). The primary loop consists of the CLOCK:BMAL1 heterodimer, which activates the transcription of Period (PER) and Cryptochrome (CRY) genes. PER and CRY proteins accumulate, heterodimerize, and translocate to the nucleus to inhibit CLOCK:BMAL1 activity, thereby repressing their own transcription.

NR1D1 is a component of a secondary, stabilizing loop. CLOCK:BMAL1 also drives the transcription of NR1D1 and its paralog NR1D2. The NR1D1 protein, in turn, represses the transcription of BMAL1 (ARNTL) by binding to RevRE elements in its promoter. This creates a rhythmic expression of BMAL1 that is anti-phase to NR1D1. This auxiliary loop is not essential for the generation of circadian rhythms per se, but it is critical for the robustness, amplitude, and period stability of the oscillation. Disruption of NR1D1 leads to a shortened circadian period and altered amplitude of clock gene expression [2].

```mermaid
graph TD
    subgraph Cytoplasm
        CLOCK_BMAL1["CLOCK:BMAL1 Complex"] -->|"Phosphorylation"| PER_CRY["PER:CRY Complex"]
        PER_CRY -->|"Accumulation & Nuclear Entry"| NUCLEUS
    end

    subgraph Nucleus
        CLOCK_BMAL1_N["CLOCK:BMAL1"] -->|"Activates"| EBOX["E-box Elements"]
        EBOX -->|"Transcription"| NR1D1_mRNA["NR1D1 mRNA"]
        EBOX -->|"Transcription"| PER_CRY_mRNA["PER/CRY mRNA"]
        NR1D1_mRNA -->|"Translation"| NR1D1_PROTEIN["NR1D1 Protein"]
        PER_CRY_mRNA -->|"Translation"| PER_CRY_PROTEIN["PER/CRY Protein"]
        NR1D1_PROTEIN -->|"Binds RevRE"| REVRE["RevRE Elements"]
        REVRE -->|"Represses"| BMAL1_GENE["BMAL1 Gene"]
        BMAL1_GENE -->|"mRNA"| BMAL1_PROTEIN["BMAL1 Protein"]
        BMAL1_PROTEIN -->|"Heterodimerizes with"| CLOCK_PROTEIN["CLOCK Protein"]
        CLOCK_PROTEIN --> CLOCK_BMAL1_N
        PER_CRY_PROTEIN -->|"Inhibits"| CLOCK_BMAL1_N
    end

    CLOCK_BMAL1 -->|"Activates"| NR1D1_mRNA
    NR1D1_PROTEIN -->|"Recruits NCoR/HDAC3"| REPRESSION["Transcriptional Repression"]
```

### 3.2 Metabolic Regulation: Lipid and Glucose Homeostasis

NR1D1 is a critical regulator of cellular and systemic metabolism. In the liver, it controls the expression of genes involved in lipid synthesis (lipogenesis), fatty acid oxidation, and gluconeogenesis. NR1D1 represses the expression of key lipogenic transcription factors, such as SREBP1C, and enzymes like fatty acid synthase (FASN). This repression is rhythmic, leading to a daily oscillation in hepatic lipid content. Deletion of NR1D1 in mice results in hepatic steatosis, particularly when challenged with a high-fat diet [5]. The mechanism involves the derepression of lipogenic genes and a concomitant decrease in fatty acid oxidation.

In the context of glucose metabolism, NR1D1 represses the expression of gluconeogenic enzymes, including glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK). This action is modulated by apolipoprotein A-IV (ApoA-IV), which has been shown to stimulate NR1D1 expression and thereby suppress hepatic glucose production [6]. This pathway is also relevant to the action of the clock gene BMAL1 in the kidney, where it inhibits SGLT2 expression via the NR1D1/NRF1 pathway, thereby regulating glucose reabsorption [7].

NR1D1 also plays a role in adipose tissue biology. It is required for the proper expansion of adipose tissue during obesity. Adipocyte-specific deletion of NR1D1 leads to a failure of adipose tissue expansion, resulting in ectopic lipid deposition and systemic insulin resistance, a phenotype distinct from global deletion [8]. This highlights the cell-type-specific and context-dependent functions of NR1D1.

### 3.3 Inflammation and Immune Response

NR1D1 is a potent anti-inflammatory regulator. It represses the expression of multiple pro-inflammatory cytokines and chemokines by interfering with the NF-κB signaling pathway. Mechanistically, NR1D1 can physically interact with the p65 subunit of NF-κB, preventing its binding to target gene promoters. It also represses the expression of Toll-like receptor 4 (TLR4), reducing the sensitivity of cells to inflammatory stimuli.

This anti-inflammatory role is critical in several tissues. In the retina, NR1D1 activation suppresses microglial inflammation, which is a key driver of retinal degenerative diseases [9]. In the lungs, NR1D1 alleviates asthma by repressing GATA3 expression and Th2 cell differentiation [10]. In the gut, NR1D1 protects against colitis by modulating mitophagy and the VDAC1/NF-κB pathway [1, 11]. The anti-inflammatory function of NR1D1 is also crucial for host defense. It has been shown to be required for the clearance of Mycobacterium tuberculosis by regulating autophagy [2]. Conversely, in a model of Streptococcus agalactiae infection in Nile Tilapia, NR1D1 expression is altered, suggesting its involvement in the inflammatory response to bacterial pathogens [2].

### 3.4 Autophagy and Mitophagy

NR1D1 directly regulates the autophagy machinery. It represses the transcription of autophagy-related genes, such as ATG5 and BNIP3. In granulosa cells, NR1D1-mediated inhibition of ATG5 controls autophagy and follicular atresia [3]. In the context of ulcerative colitis, NR1D1 promotes BNIP3-mediated mitophagy, which is essential for the clearance of damaged mitochondria and the maintenance of intestinal epithelial cell integrity [1]. The regulation of mitophagy by NR1D1 is also implicated in the response to simulated microgravity, where its degradation leads to circadian disruption [4].

### 3.5 Protein-Protein Interaction Networks

The function of NR1D1 is dependent on its interaction with a large network of proteins. The most critical interaction is with the nuclear receptor corepressor (NCoR1/NCOR1) complex. NR1D1 recruits NCoR1, which in turn recruits HDAC3, leading to histone deacetylation and chromatin compaction. This interaction is ligand-dependent, with heme and synthetic agonists stabilizing the NR1D1-NCoR1 interaction. NR1D1 also interacts with other corepressors, such as SMRT (Silencing Mediator for Retinoid and Thyroid Hormone Receptors), although NCoR1 is the primary partner.

Beyond corepressors, NR1D1 interacts with a variety of transcription factors and signaling proteins. It interacts with the CLOCK:BMAL1 complex, and with the glucocorticoid receptor (GR), which suppresses NR1D1 expression [3]. It also interacts with the orphan nuclear receptor NR2E3 in the retina, where they co-regulate the expression of photoreceptor-specific genes [5, 6]. This interaction is critical for retinal development and function, and mutations in either gene can lead to retinitis pigmentosa [7]. In the nucleus accumbens, NR1D1 interacts with the circadian machinery to modulate sociability and anxiety-related behavior [8].

## 4. Pathogenic Hotspot Mutations & Clinical Differentials

Mutations and polymorphisms in NR1D1 are associated with a wide range of clinical phenotypes, spanning psychiatric, metabolic, and neoplastic diseases.

### 4.1 Psychiatric and Neurodevelopmental Disorders

The NR1D1 gene has been extensively studied in the context of mood disorders. A study in the Japanese population found an association between NR1D1 polymorphisms and major depressive disorder (MDD) and bipolar disorder (BD) [9]. Furthermore, a specific polymorphism (rs2071427) has been linked to the response to fluvoxamine, a selective serotonin reuptake inhibitor (SSRI), in MDD patients [10]. This suggests that NR1D1 genotype could be a predictor of antidepressant response. In bipolar disorder, NR1D1 polymorphisms have been investigated for their role in lithium response. A study on Sardinian bipolar patients found that the interaction between DGKH and NR1D1 gene polymorphisms may influence the efficacy of lithium prophylaxis [11]. More recent work has confirmed that the NR1D1 SNP rs2071427 is associated with lithium response, potentially serving as a biomarker for treatment selection [1]. However, a separate study in a Han Chinese population found no significant association between NR1D1 variants and BD, indicating potential ethnic-specific effects [2].

NR1D1 has also been implicated in autism spectrum disorder (ASD). Screening of ASD patients identified mutations in the coding regions of NR1D1, including a specific mutation that affects brain development [3]. The study demonstrated that NR1D1 plays a role in neuronal development, and its dysfunction may contribute to the pathophysiology of ASD.

### 4.2 Metabolic and Cardiovascular Diseases

Polymorphisms in NR1D1 are associated with circadian typologies (chronotype) [4]. The rs2314339 and rs72836608 polymorphisms have been linked to coronary artery disease (CAD) in men, suggesting a sex-specific role for NR1D1 in cardiovascular risk [5]. The gene is also implicated in the regulation of lipid metabolism, and its dysregulation contributes to non-alcoholic fatty liver disease (NAFLD) [6]. NR1D1 expression is altered in the liver during aging, and its co-regulation with PPARα is important for age-related changes in lipid metabolism [7]. Furthermore, NR1D1 is a key player in the development of abdominal aortic aneurysms (AAA), where it regulates the expression of the mitochondrial enzyme aconitase-2 (ACO2) [8].

### 4.3 Cancer: A Context-Dependent Role

NR1D1 exhibits dual roles in tumorigenesis, acting as either a tumor suppressor or an oncogene depending on the cellular context [9, 10].

- **Tumor Suppressor:** In several cancers, NR1D1 expression is downregulated, and its loss is associated with increased proliferation, invasion, and poor prognosis. In bladder cancer, NR1D1 is considered a potential therapeutic target, as its overexpression inhibits cancer cell growth [11]. In colorectal cancer, NR1D1 expression is associated with a favorable prognosis and a less aggressive tumor phenotype [1]. In breast cancer, an RNAi screen identified NR1D1 as a survival factor for ERBB2-positive cells, suggesting that its inhibition could be a therapeutic strategy [2]. In colon cancer, downregulation of NR1D1 increases cell motility and invasiveness [3].
- **Oncogene:** Conversely, in some contexts, NR1D1 can promote tumorigenesis. Its role in regulating metabolism and the cell cycle can be co-opted by cancer cells to support their growth. The dual nature of NR1D1 in cancer highlights the importance of understanding the specific tumor microenvironment and genetic background.

### 4.4 Gene Fusions in Soft Tissue Tumors

A distinct class of pathogenic NR1D1 alterations involves chromosomal rearrangements that create fusion genes. The most well-characterized is the NR1D1::MAML1 fusion, which has been identified in a rare subset of soft tissue tumors with epithelioid and spindle cell morphology [4, 5, 6]. These tumors often mimic other sarcomas, such as pseudomyogenic hemangioendothelioma, making diagnosis challenging. The fusion protein retains the N-terminal DBD of NR1D1 but replaces the C-terminal LBD with the transcriptional activation domain of MAML1, resulting in a chimeric protein with aberrant transcriptional activity. The presence of this fusion is a defining molecular feature of this emerging tumor entity.

### 4.5 Other Pathologies

- **Retinal Diseases:** NR1D1 interacts with NR2E3 to regulate photoreceptor gene expression. Mutations in NR2E3 cause retinitis pigmentosa, and NR1D1 has been shown to act as a modifier gene that can rescue the retinal phenotype in mouse models [7]. This suggests that NR1D1 could be a therapeutic target for certain forms of RP [7].
- **Asthma:** NR1D1 alleviates asthma by suppressing Th2 cell differentiation [10].
- **Liver Fibrosis:** NR1D1 is involved in the regulation of hepatic stellate cell activation and lipophagy, making it a target for anti-fibrotic therapies [8, 9].
- **Inflammatory Bowel Disease (IBD):** NR1D1 protects against colitis by regulating mitophagy and the NF-κB pathway [1, 11].
- **Amyotrophic Lateral Sclerosis (ALS):** In silico studies suggest that NR1D1-linked chronotherapy, potentially with melatonin as an adjuvant, could be a therapeutic avenue for ALS [10].

## 5. Host-Pathogen & Viral Interactions

NR1D1 is an important player in the host response to various pathogens, primarily through its regulation of inflammation and autophagy.

### 5.1 Bacterial Infections

- **Mycobacterium tuberculosis:** NR1D1 is required for efficient autophagy-mediated clearance of Mycobacterium tuberculosis in macrophages [2]. The mechanism involves NR1D1-dependent regulation of autophagy genes, which enhances the delivery of the bacteria to lysosomes for degradation.
- **Streptococcus agalactiae:** In Nile Tilapia, NR1D1 expression is modulated in the brain following S. agalactiae challenge, indicating its involvement in the central inflammatory response to this pathogen [2].
- **Gut Microbiota:** NR1D1 links sleep deprivation to intestinal homeostasis via microbiota-derived taurine. Sleep deprivation alters the gut microbiota, leading to changes in taurine metabolism, which in turn affects NR1D1 expression and intestinal barrier function [11].

### 5.2 Viral Infections

- **Respiratory Syncytial Virus (RSV):** In RSV-infected mouse lungs, Notch signaling suppresses NR1D1/BNIP3-dependent mitophagy, which aggravates the inflammatory response [1]. This suggests that NR1D1-mediated mitophagy is a protective mechanism against viral-induced lung inflammation.

### 5.3 Environmental Toxicants and Host-Pathogen Interactions

NR1D1 is a molecular target for several environmental toxicants, which can disrupt its function and contribute to disease.

- **Bisphenol A (BPA):** BPA disrupts circadian rhythms and induces anxiety-like behavior and inflammation in zebrafish larvae by downregulating NR1D1 [2]. BPA also disrupts circadian locomotor rhythms via m6A-dependent nr1d1 destabilization [3]. In Leydig cells, BPA attenuates testosterone production through the inhibition of NR1D1 signaling [4].
- **Cigarette Smoke:** Cigarette smoke suppresses NR1D1 expression in the lungs, which may contribute to the disruption of circadian rhythms and increased inflammation in smokers [5, 6]. This suppression is also linked to the inactivation of NR1D1 as a tumor suppressor gene, potentially contributing to lung cancer development [6].
- **Ozone:** Acute and repeated ozone exposures differentially affect circadian clock gene expression, including Nr1d1, in mice, linking air pollution to circadian disruption [7].
- **Ammonia:** Ammonia exposure in pigs disturbs the pulmonary circadian clock gene network, including Nr1d1, leading to lung injury [8].

## 6. Pharmacogenomics, Drug Targets & Small-Molecule Inhibitors

The unique structural and functional properties of NR1D1 make it an attractive drug target. Unlike classical nuclear receptors, NR1D1 acts as a repressor, and its ligands are inverse agonists that stabilize its repressive conformation.

### 6.1 Synthetic Ligands and Investigational Compounds

- **Heme:** The natural ligand, heme, is essential for NR1D1 function. Synthetic heme analogs are being explored to modulate NR1D1 activity.
- **GSK4112:** This is a first-generation synthetic NR1D1 agonist that binds to the LBD and enhances the recruitment of NCoR1, thereby increasing transcriptional repression. It has been used extensively in preclinical studies to probe NR1D1 function.
- **SR9009 and SR9011:** These are potent, bioavailable NR1D1 agonists that have been shown to have profound effects on metabolism, including reducing fat mass and improving glucose homeostasis in mouse models. They also exhibit anti-cancer and anti-inflammatory properties. SR9009 has been shown to inhibit the growth of cancer cells, including glioblastoma and breast cancer cells.
- **Dihydroartemisinin (DHA):** This antimalarial drug has been shown to require NR1D1 to regulate hepatic stellate cell lipophagy and alleviate liver fibrosis [8].
- **Betulinic Acid (BHA):** This natural compound alleviates DSS-induced colitis in mice by modulating NR1D1 and the VDAC1/NF-κB pathway [11].
- **Toluquinol:** This compound modulates NR1D1 and circadian rhythm in lung cancer cells, suggesting its potential in circadian medicine [9].
- **Stephanoside B:** A bioactive compound from Gymnema inodorum, it modulates metabolic gene expression and lengthens the circadian bmal1 oscillation period, potentially through NR1D1 [10].

### 6.2 Therapeutic Applications and Chronotherapy

The concept of chronotherapy, where drug administration is timed to coincide with the body's natural rhythms, is particularly relevant for NR1D1-targeted therapies. Since NR1D1 expression is rhythmic, the efficacy of its agonists may vary depending on the time of day. This has been demonstrated in the context of time-restricted feeding, which alleviates heat stress-induced liver ferroptosis in piglets via NR1D1-mediated transcription modulation [11].

- **Metabolic Diseases:** NR1D1 agonists are being developed for the treatment of obesity, type 2 diabetes, and dyslipidemia. They have been shown to reduce hepatic steatosis, improve insulin sensitivity, and lower blood glucose levels.
- **Inflammatory Diseases:** NR1D1 agonists have shown promise in preclinical models of asthma, colitis, and retinal inflammation [9, 10, 11].
- **Cancer:** The context-dependent role of NR1D1 in cancer means that both agonists and antagonists could be therapeutically useful. In cancers where NR1D1 acts as a tumor suppressor, agonists would be beneficial. In cancers where it acts as an oncogene, antagonists might be required.
- **Neuropsychiatric Disorders:** Given its association with mood disorders and lithium response, NR1D1 is a potential target for the development of new antidepressants and mood stabilizers [1, 10].

### 6.3 Pharmacogenomics

The NR1D1 gene is subject to pharmacogenomic influences. Polymorphisms in NR1D1 have been associated with the response to fluvoxamine in MDD [10] and to lithium in bipolar disorder [1, 11]. This suggests that genotyping NR1D1 could be used to personalize treatment selection for patients with mood disorders. Furthermore, the expression of NR1D1 is altered by various drugs, including paclitaxel, which disrupts circadian gene transcription [1].

## 7. Bioinformatic Resources & Database Accessions

The following table provides key database accessions and resources for the NR1D1 gene and protein.

| **Database** | **Identifier / Link** | **Description** |
| :--- | :--- | :--- |
| **NCBI Gene** | [2](https://www.ncbi.nlm.nih.gov/gene/9572) | Gene-specific information, genomic context, and links to other NCBI resources. |
| **Ensembl** | [ENSG00000126368](https://www.ensembl.org/Homo_sapiens/Gene/Summary?db=core;g=ENSG00000126368) | Comprehensive genome annotation, transcripts, and variation data. |
| **UniProt** | [P20393](https://www.uniprot.org/uniprotkb/P20393/entry) | Protein sequence, function, domain architecture, and post-translational modifications. |
| **RCSB PDB** | [3N00](https://www.rcsb.org/structure/3N00), [5UD0](https://www.rcsb.org/structure/5UD0) | Experimentally determined 3D structures of the LBD and DBD. |
| **Gene Ontology (GO)** | [GO:0000978](https://www.ebi.ac.uk/QuickGO/term/GO:0000978), [GO:0003707](https://www.ebi.ac.uk/QuickGO/term/GO:0003707), [GO:0005515](https://www.ebi.ac.uk/QuickGO/term/GO:0005515) | Functional annotations for DNA-binding transcription factor activity, nuclear receptor activity, and protein binding. |
| **ClinVar** | [NR1D1](https://www.ncbi.nlm.nih.gov/clinvar/?term=NR1D1%5Bgene%5D) | Database of human genetic variants and their relationship to human health. |
| **STRING** | [NR1D1 (P20393)](https://string-db.org/network/9606.ENSP00000246603) | Protein-protein interaction networks. |
| **BioGRID** | [NR1D1](https://thebiogrid.org/108369) | Curated protein and genetic interactions. |
| **OMIM** | [3](https://www.omim.org/entry/602408) | Catalog of human genes and genetic phenotypes. |

## Related Clinical & Scientific Guides

* [PMCH Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/developmental-biology/pmch-gene-structure-function-pathway)
* [CYLC1 Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/developmental-biology/cylc1-gene-structure-function-pathway)
* [CRX Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/developmental-biology/crx-gene-structure-function-pathway)

## References

[1] Wang, Z., Liu, Z., Zhu, W., Zhang, M., Huang, S., Cao, J., Wang, M., Yi, M., Gao, F., Lu, M., & Ke, X. (2025). Clock gene NR1D1 mediated inflammatory response after Streptococcus agalactiae challenge in Nile Tilapia (Oreochromis niloticus) brain. *Aquaculture Reports*. [URL](https://www.semanticscholar.org/paper/5b5e43ee581fc41513d2ec4eede54803f028e12b)

[2] Yang, Y., Bai, Y., Wang, X., Guo, Y., Yu, Z., Feng, D., Zhang, F., Li, D., & Han, P. (2023). Clock gene NR1D1 might be a novel target for the treatment of bladder cancer. *Urologic Oncology*. [URL](https://www.semanticscholar.org/paper/3f9868b75157a32e69c32eb1a956033456c5bba3)

[3] Wang, Z., Huang, Y., Chu, F., Ji, S., Liao, K., Cui, Z., Chen, J., & Tang, S. (2021). Clock Gene Nr1d1 Alleviates Retinal Inflammation Through Repression of Hmga2 in Microglia. *Journal of Inflammation Research*. [URL](https://www.semanticscholar.org/paper/d325d30b8e0d2533a729f3236543b31c59e2fa95)

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