GO:0071939 vitamin A import into cell: Retinoid Uptake Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0071939 (vitamin A import into cell) describes the directed movement of vitamin A (retinol, retinal, or retinoic acid) from outside a cell across the plasma membrane into the cytosol.
• The retinal pigment epithelium (RPE) is a classic model for vitamin A import, where retinol uptake and esterification are essential for the visual cycle.
• ABCA4, a retina-specific ABC transporter, is critical for retinoid transport and its dysfunction causes Stargardt disease and other retinopathies.
• Carotenoid and retinoid metabolism is compartmentalized within cells, influencing how vitamin A is imported and utilized.
• Metabolic network modeling and transcriptomic studies reveal that vitamin A import is integrated with broader metabolic reprogramming in germ cells and other tissues.
• CRISPR-based knockout, knock-in, and overexpression models enable causal testing of genes involved in vitamin A import and related retinoid trafficking.
Description
Vitamin A import into cell (GO:0071939) is a biological process defined as the directed movement of vitamin A from outside a cell, across the plasma membrane, and into the cytosol. Vitamin A encompasses several retinoid derivatives of beta-carotene, primarily retinol, retinal, and retinoic acid, which are essential for vision, embryonic development, immune function, and cellular differentiation. The retinal pigment epithelium (RPE) is a specialized tissue where vitamin A import is tightly linked to the visual cycle, and defects in this process contribute to retinal degenerations. Understanding the molecular players and regulatory mechanisms of vitamin A import is therefore critical for both basic cell biology and therapeutic development. Recent advances in metabolic modeling and transcriptomics have highlighted that vitamin A import is not an isolated event but is integrated with cellular metabolic reprogramming, particularly in germ cells and during meiotic fate decisions. Compartmentalization of carotenoid and retinoid metabolism further underscores the need to study import in a cell-type-specific context. This article synthesizes authoritative GO annotations and published literature to provide a research-grade overview of GO:0071939, its associated genes, disease relevance, and experimental strategies for investigation.
vitamin A import into cell At A Glance
| GO ID | GO:0071939 |
|---|---|
| GO term | vitamin A import into cell |
| Ontology | biological_process |
| Synonym | vitamin A import; vitamin A uptake |
| Definition | The directed movement of vitamin A from outside of a cell, across the plasma membrane and into the cytosol. |
| Major function | Uptake of retinol, retinal, or retinoic acid into the cell for vision, development, and metabolism. |
| Related processes | Visual cycle, retinoid metabolism, carotenoid compartmentalization. |
| Key tissues | Retinal pigment epithelium, testis, liver, and other retinoid-dependent tissues. |
What Is GO:0071939?
GO:0071939 (vitamin A import into cell) is the directed movement of vitamin A from outside of a cell, across the plasma membrane and into the cytosol. Vitamin A is any of several retinoid derivatives of beta-carotene, primarily retinol, retinal, or retinoic acid. Synonyms include vitamin A import and vitamin A uptake.
Why Is vitamin A import into cell Important in Cell Biology?
Vitamin A import into cell is fundamental for vision, embryonic development, immune function, and cellular differentiation, as retinoids are essential signaling molecules and chromophore precursors. Defects in retinoid transport and metabolism are linked to retinal degenerations such as Stargardt disease, highlighting the clinical importance of this process. Moreover, metabolic network modeling and transcriptomic studies show that vitamin A import is integrated with broader metabolic reprogramming in germ cells and other tissues, influencing meiotic fate decisions and toxicological responses. Thus, understanding GO:0071939 provides insights into both normal physiology and disease mechanisms.
• Essential for the visual cycle in the retinal pigment epithelium and photoreceptor function.
• Mutations in ABCA4, a retinoid transporter, cause Stargardt disease and other retinopathies.
• Compartmentalization of carotenoid metabolism affects vitamin A import efficiency and utilization.
• Vitamin A import is linked to meiotic fate decisions in mouse testicular germ cells.
• Sex-specific metabolic differences influence retinoid handling and toxicological responses.
• Metabolic network modeling reveals germ cell metabolic dependencies including retinoid pathways.
• Vitamin A derivatives are used in wound healing and antimicrobial applications.
• Disruption of vitamin A import can lead to developmental defects and immune dysfunction.
What Happens During vitamin A import into cell?
Recognition and binding at the plasma membrane
In simple terms: The cell first recognizes vitamin A molecules outside and binds them at its surface.
Vitamin A import begins with the interaction of retinol or other retinoids with the plasma membrane. In the retinal pigment epithelium, this process is critical for the visual cycle, where retinol is taken up from the extracellular space. The binding may involve membrane-associated proteins or lipid rafts, although specific receptors for retinol uptake remain incompletely defined.
Translocation across the plasma membrane
In simple terms: Vitamin A moves through the cell membrane into the interior.
Following binding, vitamin A is translocated across the plasma membrane into the cytosol. This step may be facilitated by transport proteins or through passive diffusion, depending on the cell type. Compartmentalization of carotenoid metabolism suggests that membrane transporters or binding proteins could direct retinoids to specific intracellular destinations.
Intracellular processing and esterification
In simple terms: Once inside, vitamin A is chemically modified and stored or used.
After entering the cytosol, retinol is often esterified to retinyl esters for storage or converted to retinal and retinoic acid for signaling and vision. In the RPE, this processing is essential for regenerating the visual chromophore. ABCA4 plays a role in transporting retinoid derivatives across membranes, and its dysfunction leads to toxic retinoid accumulation.
Integration with metabolic networks
In simple terms: Vitamin A import is connected to the cell's overall metabolism.
Vitamin A import is not an isolated event; it is integrated with broader metabolic pathways. Metabolic modeling of germ cells and sex-specific tissues has revealed that retinoid metabolism intersects with meiotic fate decisions and toxicological responses. This integration ensures that vitamin A is available for diverse cellular functions.
Key Genes Involved in GO:0071939 vitamin A import into cell
The following genes and proteins are implicated in vitamin A import and related retinoid metabolism, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| ABCA4 | Retinoid transporter in photoreceptors and RPE | Mutations cause Stargardt disease; model for retinoid transport |
| RPE65 | Retinoid isomerase in visual cycle | Essential for regenerating 11-cis-retinal; RPE model |
| LRAT | Lecithin retinol acyltransferase | Esterifies retinol for storage; RPE and liver studies |
| CRBP1 | Cellular retinol-binding protein | Facilitates intracellular retinol trafficking |
| CRALBP | Cellular retinaldehyde-binding protein | Handles retinal in visual cycle |
| STRA6 | Retinol uptake receptor | Mediates retinol import in RPE and other tissues |
| BCO1 | Beta-carotene oxygenase 1 | Converts beta-carotene to retinal; compartmentalization |
| BCO2 | Beta-carotene oxygenase 2 | Carotenoid cleavage; metabolic compartmentalization |
| TTR | Transthyretin | Transports retinol-binding protein and retinol in blood |
| RBP4 | Retinol-binding protein 4 | Delivers retinol to tissues; uptake studies |
| ALDH1A1 | Retinaldehyde dehydrogenase | Synthesizes retinoic acid from retinal |
| CYP26A1 | Retinoic acid hydroxylase | Degrades retinoic acid; regulates retinoid levels |
| HuR | RNA-binding protein | Regulates nuclear import of proteins; potential link to retinoid metabolism |
| mTOR | Metabolic regulator | Integrates nutrient signals with retinoid metabolism |
| SLC family transporters | Membrane transport | Potential facilitators of vitamin A import |
How Is vitamin A import into cell Regulated?
Vitamin A import into cell is regulated at multiple levels. In the retinal pigment epithelium, the visual cycle demands tight control of retinol uptake and esterification, which is influenced by RPE65 and LRAT activity. ABCA4-mediated retinoid transport is critical for preventing toxic accumulation, and its expression is regulated in response to retinoid load. Metabolic modeling suggests that mTOR signaling and nutrient availability may integrate with retinoid metabolism in germ cells and other tissues. Additionally, RNA-binding proteins such as HuR can regulate nuclear import of proteins, potentially affecting retinoid-related transcription factors.
vitamin A import into cell and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| ABCA4 | Stargardt disease, cone-rod dystrophy | Knockout and point-mutation models in RPE cells |
| RPE65 | Leber congenital amaurosis | Knock-in of patient mutations in RPE |
| LRAT | Retinal degeneration | Knockout mouse and cell models |
| STRA6 | Matthew-Wood syndrome | Overexpression and knockout in retinoid-dependent cells |
| BCO1 | Carotenoid metabolism disorders | Knockout models for beta-carotene conversion |
Stargardt disease and ABCA4 retinopathies
Mutations in ABCA4, a gene encoding a retina-specific ABC transporter, cause Stargardt disease and other retinopathies. ABCA4 dysfunction leads to accumulation of toxic retinoid derivatives, highlighting the importance of proper vitamin A import and transport in retinal health.
Visual cycle defects and retinal degeneration
The retinal pigment epithelium is central to vitamin A import for the visual cycle. Defects in RPE65, LRAT, or STRA6 can impair retinol uptake and processing, leading to retinal degeneration and vision loss.
Metabolic and developmental disorders
Vitamin A import is linked to meiotic fate decisions in germ cells, and disruptions may affect fertility and development. Sex-specific metabolic differences in retinoid handling also influence toxicological responses, suggesting broader implications for metabolic disorders.
From vitamin A import into cell-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does gene X regulate vitamin A import? | CRISPR knockout in RPE or HeLa cells followed by retinol uptake assay |
| What is the effect of a patient mutation on transport? | Point-mutation knock-in using CRISPR in cell lines |
| Can a tagged protein track vitamin A import? | Knock-in of fluorescent tag (e.g., GFP) at endogenous locus |
| Does overexpression enhance import? | Overexpression of candidate transporters in retinoid-responsive cells |
| Which genes are essential for visual cycle? | CRISPR library screening in RPE cells |
| How does metabolism integrate with import? | Metabolic modeling combined with transcriptomics |
How to Study the vitamin A import into cell Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Retinol uptake assay | Rate and extent of vitamin A import | RPE and other cell lines |
| RNA-seq | Gene expression changes | Identifying regulators of import |
| Metabolic modeling | Flux through retinoid pathways | Germ cell and tissue-specific metabolism |
| Proteomics | Protein interactions and abundance | ABCA4 and transporter complexes |
| Live-cell imaging | Intracellular trafficking | Visualizing retinoid movement |
| CRISPR screening | Essential genes for import | Functional genomics in RPE cells |
| Lipidomics | Retinoid species quantification | Measuring esterification and storage |
Retinol uptake assays
Radiolabeled or fluorescent retinol can be used to measure import kinetics in cultured cells. This method is standard for studying vitamin A import in RPE and other cell types.
Transcriptomics and metabolic modeling
RNA-seq and metabolic network modeling reveal genes and pathways associated with vitamin A import, as demonstrated in germ cell studies.
Proteomics and interactomics
Mass spectrometry-based proteomics can identify proteins interacting with retinoid transporters, such as ABCA4, providing mechanistic insights.
Imaging and live-cell tracking
Fluorescent retinoid analogs and tagged proteins enable real-time visualization of vitamin A import and intracellular trafficking.
How CRISPR Can Be Used to Study GO:0071939 vitamin A import into cell
Knockout
CRISPR knockout of candidate genes such as ABCA4 or STRA6 in RPE cells can reveal their requirement for vitamin A import. Loss-of-function models help establish causality.
Point Mutation
Introducing patient-specific point mutations (e.g., in ABCA4) via CRISPR allows study of transport defects and retinoid accumulation in isogenic backgrounds.
Knock-in
Knock-in of fluorescent tags or reporter genes at endogenous loci enables tracking of vitamin A import proteins in live cells.
Overexpression
Overexpression of transporters like STRA6 or RBP4 can enhance vitamin A import and test sufficiency in cell models.
How EDITGENE Supports vitamin A import into cell Research
Researchers studying vitamin A import into cell-related genes often need to determine whether a candidate gene is causally involved in retinoid uptake, transport, or metabolism. EDITGENE provides comprehensive CRISPR-based services to generate precisely engineered cell models for such functional studies.
Contact EDITGENE today to design your custom CRISPR model for vitamin A import into cell research.
Frequently Asked Questions About vitamin A import into cell
What is GO:0071939?
GO:0071939 is the Gene Ontology term for vitamin A import into cell, describing the directed movement of vitamin A from outside a cell across the plasma membrane into the cytosol.
What genes are involved in vitamin A import into cell?
Key genes include ABCA4, RPE65, LRAT, STRA6, and CRBP1, which facilitate retinoid transport and metabolism.
How is vitamin A import studied?
Common methods include retinol uptake assays, RNA-seq, metabolic modeling, and CRISPR screens.
Why is vitamin A import important for vision?
The retinal pigment epithelium requires vitamin A import for the visual cycle, and defects lead to retinal degeneration.
What diseases are linked to defective vitamin A import?
Stargardt disease, Leber congenital amaurosis, and other retinopathies are associated with mutations in ABCA4, RPE65, and LRAT.
Can CRISPR be used to study vitamin A import?
Yes, CRISPR knockout, knock-in, and overexpression models enable functional studies of genes involved in retinoid uptake.
What is the role of ABCA4 in vitamin A import?
ABCA4 transports retinoid derivatives across membranes, and its dysfunction causes toxic retinoid accumulation in Stargardt disease.
How does metabolic modeling help understand vitamin A import?
Metabolic network modeling integrates transcriptomic and metabolic data to predict flux through retinoid pathways in germ cells and other tissues.
Is vitamin A import compartmentalized?
Yes, carotenoid and retinoid metabolism is compartmentalized within cells, affecting import and utilization.
What cell models are used for vitamin A import research?
RPE cells, HeLa cells, and germ cell models are commonly used, with CRISPR engineering to test gene function.
Conclusion
GO:0071939 (vitamin A import into cell) is a critical biological process with profound implications for vision, development, and metabolism. The retinal pigment epithelium serves as a key model, where genes such as ABCA4, RPE65, and STRA6 orchestrate retinoid uptake and processing. Dysregulation of this process leads to retinal degenerations and potentially other metabolic disorders. Continued research using CRISPR-based models and metabolic modeling will further elucidate the mechanisms and therapeutic targets associated with vitamin A import.
References
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- 2. Al-Khuzaei S et al.. 2021. An Overview of the Genetics of ABCA4 Retinopathies, an Evolving Story.. Genes (Basel) 12(8) PMID: 34440414
- 3. Palczewski G et al.. 2014. Evidence for compartmentalization of mammalian carotenoid metabolism.. FASEB J 28(10):4457-69 PMID: 25002123
- 4. Zhang X et al.. 2023. Transcriptional metabolic reprogramming implements meiotic fate decision in mouse testicular germ cells.. Cell Rep 42(7):112749 PMID: 37405912
- 5. Moore CJ et al.. 2023. Metabolic modeling of sex-specific tissue predicts mechanisms of differences in toxicological responses.. bioRxiv PMID: 36798158
- 6. Gheorghita D et al.. 2022. Essential Oils as Antimicrobial Active Substances in Wound Dressings.. Materials (Basel) 15(19) PMID: 36234263
- 7. Whitmore LS et al.. 2015. Dissecting Germ Cell Metabolism through Network Modeling.. PLoS One 10(9):e0137607 PMID: 26367011
- 8. Zhang W et al.. 2016. RNA-binding protein HuR regulates nuclear import of protein.. J Cell Sci 129(21):4025-4033 PMID: 27609837
