GO:0015798 myo-inositol transport: Transport Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0015798 myo-inositol transport describes the directed movement of myo-inositol into, out of, or within a cell via transporters or pores.
• Myo-inositol is a growth factor for animals and microorganisms and a precursor for phosphoinositides and inositol phosphates.
• Key transporters include SLC5A3 (SMIT1), SLC5A11 (SMIT2), and SLC2A13 (HMIT), which differ in ion coupling and stoichiometry.
• Dysregulated myo-inositol transport is linked to acute myeloid leukemia, where SLC5A3-dependent auxotrophy can be targeted.
• Transport is regulated by osmotic stress, glucose, and hormonal signals, affecting cellular myo-inositol homeostasis.
• CRISPR knockout, knock-in, and overexpression models enable causal dissection of transporter function in disease and metabolism.
Description
Myo-inositol transport (GO:0015798) is the biological process by which myo-inositol, a cyclohexanehexol growth factor, is moved across cellular membranes by specific transporters or pores. This process is essential for maintaining intracellular myo-inositol pools that serve as precursors for phosphatidylinositol and inositol phosphate signaling molecules. Researchers study myo-inositol transport to understand osmoregulation, metabolic homeostasis, and the pathophysiology of diseases such as acute myeloid leukemia and neurological disorders. The transport process is mediated by a family of sodium- or proton-coupled cotransporters, including SLC5A3, SLC5A11, and SLC2A13, which exhibit distinct tissue distributions and kinetic properties. Because myo-inositol cannot be synthesized in sufficient quantities by some cell types, transport is critical for survival and proliferation. This article synthesizes authoritative QuickGO data and verified PubMed literature to provide a research-grade overview of GO:0015798, its molecular players, regulatory mechanisms, disease relevance, and experimental models for investigation.
myo-inositol transport At A Glance
| GO ID | GO:0015798 |
|---|---|
| GO term | myo-inositol transport |
| Ontology | biological_process |
| Synonym | vitamin Bh transport |
| Major function | Directed movement of myo-inositol across membranes via transporters or pores |
| Substrate | Myo-inositol (1,2,3,4,5/4,6-cyclohexanehexol) |
| Key transporters | SLC5A3 (SMIT1), SLC5A11 (SMIT2), SLC2A13 (HMIT) |
| Cellular context | Plasma membrane and intracellular membranes |
| Physiological role | Maintenance of myo-inositol homeostasis for phosphoinositide synthesis and osmoregulation |
What Is GO:0015798?
GO:0015798 myo-inositol transport is defined as the directed movement of myo-inositol into, out of, or within a cell, or between cells, by means of some agent such as a transporter or pore. Myo-inositol (1,2,3,4,5/4,6-cyclohexanehexol) is a growth factor for animals and microorganisms. The term is synonymous with vitamin Bh transport and falls under the biological_process ontology aspect.
Why Is myo-inositol transport Important in Cell Biology?
Myo-inositol transport is fundamental for cellular function because myo-inositol is a precursor for phosphoinositides, which regulate signal transduction, membrane trafficking, and cell growth. Defects in transport can lead to myo-inositol depletion, affecting osmoregulation and metabolic pathways, and have been implicated in diseases such as acute myeloid leukemia, where SLC5A3-dependent myo-inositol auxotrophy represents a therapeutic vulnerability. Understanding the transport mechanisms and regulation is therefore critical for developing targeted interventions.
• Maintains intracellular myo-inositol pools required for phosphatidylinositol synthesis and signaling.
• Regulates osmotic balance in cells exposed to hypertonic stress.
• SLC5A3-dependent myo-inositol auxotrophy is a metabolic vulnerability in acute myeloid leukemia.
• Altered myo-inositol transport is associated with neurological and metabolic disorders.
• Transporters like SMIT2 and HMIT are targets for understanding ion-coupled transport mechanisms.
• Myo-inositol transport influences glucose metabolism and insulin sensitivity.
• Provides a model for studying sodium-coupled cotransport stoichiometry.
• Relevant to agricultural science, e.g., intestinal transport in poultry.
• Enables CRISPR-based functional genomics of transporter genes.
• Potential biomarker for diseases with dysregulated inositol metabolism.
What Happens During myo-inositol transport?
Substrate recognition and binding
In simple terms: The transporter first grabs myo-inositol from one side of the membrane.
Myo-inositol transporters, such as SLC5A3 and SLC5A11, recognize myo-inositol with high specificity through conserved binding pockets. The binding affinity and specificity are determined by amino acid residues in the transmembrane domains, as demonstrated by functional studies of SMIT2 and HMIT. This step is essential for initiating the transport cycle and is subject to competitive inhibition by D-glucose in some transporters.
Ion coupling and stoichiometry
In simple terms: The transporter uses sodium or protons to drive myo-inositol into the cell.
Most myo-inositol transporters are secondary active cotransporters that couple myo-inositol movement to the electrochemical gradient of Na+ or H+. The stoichiometry of ion coupling has been determined for SMIT2 and HMIT, revealing differences in coupling ratios that affect transport efficiency. For example, SMIT2 operates with a Na+:myo-inositol stoichiometry of 2:1, while HMIT is H+-coupled.
Conformational changes and translocation
In simple terms: The transporter changes shape to move myo-inositol across the membrane.
Upon substrate and ion binding, the transporter undergoes conformational changes that alternately expose the binding site to the extracellular and intracellular sides, facilitating translocation. This alternating access mechanism is a hallmark of solute carrier (SLC) transporters and has been inferred from kinetic and mutagenesis studies.
Release and resetting
In simple terms: Myo-inositol is released inside the cell, and the transporter resets for another round.
After translocation, myo-inositol is released into the cytoplasm due to reduced binding affinity, and the transporter returns to its original conformation to complete the cycle. This process is driven by the ion gradient and ensures continuous uptake as long as the gradient is maintained.
Regulation by osmotic and metabolic signals
In simple terms: The cell adjusts transport activity based on its needs and environment.
Myo-inositol transport is regulated at multiple levels, including transcriptional upregulation of SLC5A3 under hypertonic stress and modulation by glucose and hormones. For instance, high glucose inhibits myo-inositol transport in renal and intestinal brush border membranes, contributing to diabetic complications. These regulatory mechanisms help maintain myo-inositol homeostasis.
Key Genes Involved in GO:0015798 myo-inositol transport
The following genes encode transporters and related proteins that mediate or regulate myo-inositol transport (GO:0015798).
| Gene | Major Role | Research Relevance |
|---|---|---|
| SLC5A3 | Na+-coupled myo-inositol cotransporter (SMIT1) | Osmoregulation, AML auxotrophy, CNS function |
| SLC5A11 | Na+-coupled myo-inositol cotransporter (SMIT2) | Intestinal and renal transport, stoichiometry studies |
| SLC2A13 | H+-coupled myo-inositol transporter (HMIT) | Neuronal signaling, brain inositol metabolism |
| SLC5A1 | Na+/glucose cotransporter (SGLT1) | Can transport myo-inositol in some contexts |
| SLC5A2 | Na+/glucose cotransporter (SGLT2) | Renal glucose and inositol handling |
| SLC2A1 | GLUT1 glucose transporter | May influence myo-inositol uptake indirectly |
| SLC2A2 | GLUT2 glucose transporter | Intestinal and hepatic transport |
| SLC2A4 | GLUT4 glucose transporter | Insulin-responsive tissues |
| SLC5A4 | SMIT2-related transporter | Ion-coupled transport |
| SLC5A5 | Na+/iodide transporter | Homology to myo-inositol transporters |
| SLC5A8 | Na+-coupled monocarboxylate transporter | Related SLC5 family member |
| SLC5A12 | Na+-coupled lactate transporter | Related SLC5 family member |
| ITPK1 | Inositol-tetrakisphosphate 1-kinase | Inositol phosphate metabolism |
| IMPA1 | Inositol monophosphatase 1 | Myo-inositol synthesis |
| IMPA2 | Inositol monophosphatase 2 | Myo-inositol synthesis |
| ISYNA1 | Inositol-3-phosphate synthase 1 | Myo-inositol biosynthesis |
| MIOX | Myo-inositol oxygenase | Myo-inositol catabolism |
How Is myo-inositol transport Regulated?
Myo-inositol transport is regulated by osmotic stress, glucose levels, and hormonal signals. Hypertonic stress induces SLC5A3 expression to increase myo-inositol uptake for osmoregulation. High glucose inhibits myo-inositol transport in renal and intestinal brush border membranes, which may contribute to diabetic complications. Additionally, myo-inositol homeostasis is maintained through feedback regulation of synthesis and catabolism enzymes such as IMPA1 and MIOX.
myo-inositol transport and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| SLC5A3 | Acute myeloid leukemia | CRISPR knockout in AML cell lines |
| SLC5A11 | Diabetic neuropathy | Knockout mouse models |
| SLC2A13 | Neurological disorders | Neuron-specific knockout mice |
| IMPA1 | Bipolar disorder | Point mutation knock-in |
| MIOX | Diabetic nephropathy | Overexpression models |
Acute Myeloid Leukemia
SLC5A3-dependent myo-inositol auxotrophy has been identified in acute myeloid leukemia, where leukemic cells rely on myo-inositol uptake for survival. Knockdown of SLC5A3 reduces myo-inositol levels and inhibits leukemia cell growth, suggesting a potential therapeutic strategy.
Diabetic Complications
Altered myo-inositol transport is implicated in diabetic neuropathy and nephropathy. High glucose inhibits myo-inositol uptake in renal brush border vesicles, leading to intracellular myo-inositol depletion and impaired phosphoinositide signaling.
Neurological Disorders
Myo-inositol transport in the brain, mediated by HMIT (SLC2A13) and SMIT1 (SLC5A3), is critical for neuronal function. Dysregulation has been associated with mood disorders and neurodegenerative conditions, though mechanisms remain under investigation.
From myo-inositol transport-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does SLC5A3 loss affect leukemia cell survival? | CRISPR knockout in AML cell lines |
| What is the stoichiometry of SMIT2? | Point mutations in SLC5A11 followed by electrophysiology |
| Can myo-inositol transport be visualized in live cells? | Knock-in of fluorescent tags into SLC5A3 |
| Does overexpression of HMIT alter neuronal signaling? | Overexpression in primary neurons |
| How does osmotic stress regulate SLC5A3? | CRISPR activation (CRISPRa) of SLC5A3 |
| What is the role of IMPA1 in myo-inositol homeostasis? | Knockout in cell lines |
How to Study the myo-inositol transport Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Radiolabeled uptake | Transport rate and kinetics | Characterizing transporter activity |
| Electrophysiology | Ion coupling and stoichiometry | SMIT2 and HMIT studies |
| CRISPR knockout screens | Gene essentiality | Identifying SLC5A3 dependency in AML |
| Metabolomics | Myo-inositol levels | Assessing homeostasis |
| RNA-seq | Transporter expression | Tissue-specific expression profiling |
| Proteomics | Protein abundance | Validating transporter knockouts |
| Imaging | Subcellular localization | Tagged transporter knock-in |
| Site-directed mutagenesis | Functional residues | Mapping binding sites |
Transport assays
Radiolabeled myo-inositol uptake assays in cell lines or membrane vesicles measure transport activity and kinetics. These assays can be coupled with ion substitution to determine ion dependence.
Electrophysiology
Two-electrode voltage clamp or patch clamp of oocytes expressing transporters reveals electrogenic properties and stoichiometry.
CRISPR screening
Genome-wide CRISPR knockout screens can identify genes essential for myo-inositol transport and metabolism, as demonstrated in AML.
Metabolomics
Mass spectrometry-based metabolomics quantifies intracellular myo-inositol and related metabolites to assess transport function.
How CRISPR Can Be Used to Study GO:0015798 myo-inositol transport
Knockout
CRISPR knockout of SLC5A3 or other transporters can abolish myo-inositol uptake, revealing their essential roles in cell survival and metabolism. Such models are valuable for validating transporter dependency in diseases like AML.
Point Mutation
Introducing point mutations in transporter genes via CRISPR can dissect ion-binding residues and stoichiometry, as shown for SMIT2 and HMIT. This approach helps link specific residues to transport function.
Knock-in
Knock-in of fluorescent or epitope tags into endogenous transporter loci enables real-time imaging and proteomic analysis of myo-inositol transporters. This preserves native regulation and localization.
Overexpression
CRISPR activation or cDNA overexpression of transporters like SLC5A3 can increase myo-inositol uptake, useful for studying gain-of-function effects and osmotic stress responses.
How EDITGENE Supports myo-inositol transport Research
Researchers studying myo-inositol transport-related genes often need to determine whether a candidate gene is causally involved in transport, metabolism, or disease. EDITGENE provides comprehensive CRISPR-based services to generate precisely engineered cell models for such investigations.
Contact EDITGENE today to design your custom CRISPR model for myo-inositol transport research.
Frequently Asked Questions About myo-inositol transport
What is myo-inositol transport?
Myo-inositol transport (GO:0015798) is the directed movement of myo-inositol across cellular membranes by transporters or pores.
What genes are involved in myo-inositol transport?
Key genes include SLC5A3 (SMIT1), SLC5A11 (SMIT2), and SLC2A13 (HMIT), which encode sodium- or proton-coupled myo-inositol cotransporters.
What is the function of SLC5A3?
SLC5A3 encodes a Na+-coupled myo-inositol cotransporter critical for osmoregulation and is a metabolic vulnerability in acute myeloid leukemia.
How is myo-inositol transport regulated?
It is regulated by osmotic stress, glucose levels, and hormones, affecting transporter expression and activity.
What diseases are associated with myo-inositol transport?
Dysregulation is linked to acute myeloid leukemia, diabetic complications, and neurological disorders.
What is the stoichiometry of SMIT2?
SMIT2 (SLC5A11) transports myo-inositol with a Na+:myo-inositol stoichiometry of 2:1.
How can I study myo-inositol transport using CRISPR?
CRISPR knockout, knock-in, and overexpression models allow functional dissection of transporters in cell lines and primary cells.
What methods measure myo-inositol transport?
Radiolabeled uptake assays, electrophysiology, metabolomics, and CRISPR screens are commonly used.
Is myo-inositol transport important for brain function?
Yes, transporters like HMIT and SMIT1 are expressed in the brain and contribute to neuronal myo-inositol homeostasis.
What is the synonym for GO:0015798?
The synonym is vitamin Bh transport.
Conclusion
Myo-inositol transport (GO:0015798) is a vital biological process that maintains cellular myo-inositol homeostasis through specialized transporters. Its dysregulation is implicated in leukemia, diabetes, and neurological disorders, making it a compelling target for research. CRISPR-based models and advanced analytical methods provide powerful tools to dissect the molecular mechanisms and therapeutic potential of myo-inositol transport.
References
- 1. Schneider S. 2015. Inositol transport proteins.. FEBS Lett 589(10):1049-58 PMID: 25819438
- 3. Röhm K et al.. 2022. Investigation of a potential electrogenic transport-system for myo-inositol in the small intestine of laying hens.. Br Poult Sci 63(1):91-97 PMID: 34297639
- 4. Hammerman MR et al.. 1980. myo-Inositol transport in renal brush border vesicles and it inhibition by D-glucose.. Am J Physiol 239(2):F113-20 PMID: 6773422
- 5. Wei Y et al.. 2022. SLC5A3-Dependent Myo-inositol Auxotrophy in Acute Myeloid Leukemia.. Cancer Discov 12(2):450-467 PMID: 34531253
- 6. Bourgeois F et al.. 2005. Determination of transport stoichiometry for two cation-coupled myo-inositol cotransporters: SMIT2 and HMIT.. J Physiol 563(Pt 2):333-43 PMID: 15613375
- 7. Scalera V et al.. 1991. myo-inositol transport in rat intestinal brush border membrane vesicles, and its inhibition by D-glucose.. Biochim Biophys Acta 1062(2):187-92 PMID: 2004107
- 8. Su XB et al.. 2023. Regulations of myo-inositol homeostasis: Mechanisms, implications, and perspectives.. Adv Biol Regul 87:100921 PMID: 36272917
