GO:0070633 transepithelial transport: Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0070633 transepithelial transport is the directed movement of a substance from one side of an epithelium to the other [1,2].
• It is a biological_process that depends on polarized epithelial cells, tight junctions, and vectorial transport machinery [1,5].
• Key molecular players include glucose transporters (SLC2A1/GLUT1, SLC5A1/SGLT1), aquaporins (AQP1, AQP3, AQP5), ion channels (CFTR, SLC12A2/NKCC1), and ABC transporters [2,3,6,7].
• Transepithelial transport is central to nutrient uptake, ion and water homeostasis, barrier function, and drug/xenobiotic absorption [2,4,8].
• Dysregulation contributes to male infertility, salivary gland dysfunction, intestinal barrier disorders, and altered drug pharmacokinetics [1,2,4].
• CRISPR knockout, point-mutation, knock-in, and overexpression models enable causal dissection of transepithelial transport genes in Caco-2, MDCK, and organoid systems [4,8].
Description
Transepithelial transport (GO:0070633) is defined as the directed movement of a substance from one side of an epithelium to the other [1,2]. Epithelia form polarized barriers that separate distinct compartments, and their ability to move ions, nutrients, water, and xenobiotics vectorially is fundamental to organ physiology [1,5]. This process underlies blood-testis barrier function, salivary gland secretion, intestinal absorption, and renal handling of solutes [1,2,3]. Researchers study transepithelial transport to understand barrier biology, nutrient homeostasis, and drug disposition, and to identify therapeutic targets in epithelial disease [4,8]. The process requires coordinated apical and basolateral membrane transporters, paracellular seals, and vesicular trafficking pathways [5,6]. Because it is a biological_process, GO:0070633 encompasses multiple molecular mechanisms rather than a single gene product [1,2].
transepithelial transport At A Glance
| GO ID | GO:0070633 |
|---|---|
| GO term | transepithelial transport |
| Ontology | biological_process |
| Synonym | None listed in QuickGO |
| Major function | Directed movement of a substance from one side of an epithelium to the other |
| Cellular context | Polarized epithelial cells with apical and basolateral membranes |
| Key structural feature | Tight junctions and membrane transporter polarization |
| Representative substrates | Ions, glucose, water, drugs, xenobiotics |
| Related processes | Transcellular transport, paracellular transport, ion secretion, nutrient absorption |
What Is GO:0070633?
In simple terms, transepithelial transport is how a substance crosses an epithelial cell layer from one side to the other. According to the QuickGO definition, it is the directed movement of a substance from one side of an epithelium to the other [1,2]. This movement can occur through transcellular routes involving apical uptake, intracellular transit, and basolateral efflux, or through paracellular routes between cells [1,5]. The term is a biological_process and does not imply a specific substrate, transporter, or direction; it applies to ions, nutrients, water, drugs, and macromolecules [2,4,7].
Why Is transepithelial transport Important in Cell Biology?
Transepithelial transport is essential for organismal homeostasis because epithelia control the exchange of ions, water, nutrients, and xenobiotics between body compartments [1,2,3]. Defects in this process contribute to male infertility through blood-testis barrier dysfunction, salivary gland disorders through altered ion transport, and intestinal barrier diseases through impaired absorption or increased permeability [1,2,4]. It also determines the pharmacokinetics of orally administered drugs and environmental toxicants, making it a key consideration in pharmacology and toxicology [4,8].
• Maintains blood-testis barrier function and male fertility.
• Controls salivary gland ion and fluid secretion.
• Mediates intestinal glucose absorption via SGLT1 and GLUT2/GLUT1 [3,6].
• Regulates water movement through aquaporins in epithelia.
• Determines oral bioavailability and drug transport across Caco-2 monolayers [4,8].
• Supports renal and ductal ion homeostasis.
• Protects against xenobiotic toxicity by controlling epithelial permeability.
• Is dysregulated in epithelial cancers and inflammatory barrier diseases [1,4].
• Provides targets for fertility regulation and diuretic strategies [1,2].
• Enables mechanistic studies of transporter-mediated uptake and efflux [4,8].
What Happens During transepithelial transport?
Apical uptake and substrate recognition
In simple terms: The substance first enters the epithelial cell from the luminal side.
Transepithelial transport begins with substrate recognition and uptake at the apical membrane. For glucose, SGLT1 (SLC5A1) mediates Na+-dependent apical uptake, while GLUT1 (SLC2A1) and GLUT2 contribute to basolateral exit [3,6]. In salivary duct cells, apical ion channels and transporters initiate ion movement that drives fluid secretion. Aquaporins such as AQP5 facilitate apical water flux in secretory epithelia. In Caco-2 cells, apical transporters mediate uptake of small molecules such as 7,8-dihydroxyflavone and pyrethroids [4,8].
Intracellular transit and vesicular trafficking
In simple terms: Inside the cell, the substance moves across the cytoplasm, sometimes packaged in vesicles.
After apical uptake, substrates transit through the cytoplasm or are packaged into vesicles. Vesicular transport provides a short-term regulatory mechanism for transepithelial transport by shuttling transporters between intracellular stores and the plasma membrane. This trafficking allows rapid changes in transport capacity without new protein synthesis. In glucose transport, vesicular recycling of GLUT4-like transporters contributes to regulated flux in some epithelia [5,6].
Basolateral efflux and vectorial delivery
In simple terms: The substance exits the cell on the other side to complete the journey.
Basolateral efflux completes transepithelial transport. GLUT1 and GLUT2 mediate basolateral glucose exit in intestinal and other epithelia [3,6]. In duct cells, basolateral ion exchangers and channels establish the electrochemical gradients that drive secretion. ABC transporters and other efflux pumps can also mediate basolateral export of xenobiotics and metabolites. The coordinated action of apical and basolateral steps ensures net vectorial movement from one side of the epithelium to the other [1,5].
Paracellular route and tight junction control
In simple terms: Some substances pass between cells rather than through them.
The paracellular route allows substances to move between adjacent epithelial cells, regulated by tight junctions. In the blood-testis barrier, tight junctions between Sertoli cells restrict paracellular movement and create an immunological and physiological barrier. In salivary duct cells, tight junction permeability influences the final ionic composition of saliva. Paracellular transport is size- and charge-selective and can be modulated by cytokines and signaling pathways [1,2].
Regulation by hormones and signaling
In simple terms: Hormones and signals can speed up or slow down transport.
Transepithelial transport is dynamically regulated by hormones, second messengers, and vesicular trafficking. Short-term regulation often involves reversible insertion or retrieval of transporters from the plasma membrane. In salivary glands, cholinergic and adrenergic signals modulate ion and water transport. In the blood-testis barrier, cytokines and growth factors influence barrier integrity and transport function. These regulatory layers allow epithelia to adapt to physiological demand.
Key Genes Involved in GO:0070633 transepithelial transport
The following genes and proteins are experimentally implicated in transepithelial transport across epithelial systems.
| Gene | Major Role | Research Relevance |
|---|---|---|
| SLC5A1 (SGLT1) | Apical Na+-dependent glucose uptake | Intestinal glucose absorption; Caco-2 models [3,6] |
| SLC2A1 (GLUT1) | Basolateral glucose efflux | Epithelial glucose transport; blood-testis barrier [3,6] |
| SLC2A2 (GLUT2) | Facilitative glucose transport | Intestinal and renal glucose flux [3,6] |
| AQP1 | Water channel | Epithelial water transport |
| AQP3 | Water and glycerol channel | Skin and epithelial water flux |
| AQP5 | Apical water channel | Salivary and airway secretion |
| CFTR | Apical chloride channel | Ductal ion and fluid secretion |
| SLC12A2 (NKCC1) | Basolateral Na+-K+-2Cl- cotransporter | Secretory epithelia ion transport |
| ATP1A1 (Na+/K+-ATPase) | Basolateral ion pump | Driving force for transepithelial transport |
| CLDN1 | Tight junction protein | Paracellular barrier function |
| CLDN3 | Tight junction protein | Epithelial barrier selectivity |
| OCLN | Tight junction protein | Blood-testis and intestinal barriers |
| TJP1 (ZO-1) | Tight junction scaffold | Barrier assembly and regulation |
| ABCB1 (P-gp) | Apical efflux transporter | Xenobiotic and drug transport |
| ABCG2 (BCRP) | Efflux transporter | Drug transport in Caco-2 models |
| SLC22A1 (OCT1) | Organic cation transporter | Drug uptake in epithelia |
| SLC15A1 (PEPT1) | Peptide transporter | Intestinal peptide and drug uptake |
| TRPV6 | Apical calcium channel | Epithelial calcium transport |
How Is transepithelial transport Regulated?
Transepithelial transport is regulated at multiple levels. Short-term regulation occurs through vesicular trafficking that inserts or retrieves transporters from apical and basolateral membranes. Hormonal and neural signals modulate ion and water transport in salivary and other epithelia. Tight junction permeability is dynamically controlled by cytokines and signaling pathways, affecting paracellular flux. In the blood-testis barrier, growth factors and inflammatory mediators influence barrier integrity and transport function. These regulatory mechanisms allow epithelia to rapidly adjust transport rates in response to physiological demand.
transepithelial transport and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| CLDN1 | Blood-testis barrier dysfunction; male infertility | Sertoli cell knockout |
| CFTR | Salivary and ductal ion transport defects | Duct cell knockout or point mutation |
| SLC5A1 | Intestinal glucose malabsorption | Caco-2 knockout [3,6] |
| ABCB1 | Altered drug absorption and multidrug resistance | Caco-2 overexpression |
| AQP5 | Salivary and airway secretion defects | Knockout mouse or organoid |
Blood-testis barrier dysfunction and male infertility
The blood-testis barrier is a specialized epithelium-like structure formed by Sertoli cell tight junctions. Transepithelial transport across this barrier is essential for creating the immune-privileged and chemically distinct environment required for spermatogenesis. Disruption of tight junction proteins such as CLDN1, CLDN3, OCLN, and TJP1 impairs barrier function and has been linked to male infertility. Experimental models using Sertoli cell cultures and knockout mice help dissect these mechanisms.
Salivary gland dysfunction and ion transport disorders
Salivary duct cells rely on transepithelial ion transport to modify primary saliva and produce the final secretory product. Defects in apical chloride channels (CFTR), basolateral cotransporters (SLC12A2), and the Na+/K+-ATPase (ATP1A1) can lead to altered saliva composition and gland dysfunction. These mechanisms are relevant to Sjogren's syndrome, cystic fibrosis-related salivary dysfunction, and xerostomia.
Intestinal absorption and drug transport
Intestinal epithelial cells mediate transepithelial transport of nutrients, drugs, and xenobiotics. Caco-2 cell monolayers are widely used to model this process and to study transporter-mediated uptake and efflux [4,8]. Pyrethroid insecticides and the small molecule 7,8-dihydroxyflavone are transported across Caco-2 cells via specific transporters, illustrating the pharmacological and toxicological relevance of this process [4,8]. Altered transport can affect oral bioavailability and systemic exposure.
Epithelial cancers and barrier dysregulation
Transepithelial transport pathways are frequently dysregulated in epithelial cancers. Changes in tight junction protein expression and transporter activity can promote tumor cell invasion and alter drug sensitivity [1,4]. Understanding these changes may inform targeted therapies and drug delivery strategies.
From transepithelial transport-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of SLC5A1 reduce apical glucose uptake? | SLC5A1 knockout Caco-2 cells [3,6] |
| Does a point mutation in CFTR alter ductal ion transport? | CFTR point-mutation knock-in duct cells |
| Does tagging AQP5 reveal apical recycling? | AQP5 knock-in with fluorescent tag |
| Does overexpression of ABCB1 increase efflux? | ABCB1 overexpression in Caco-2 |
| Does CLDN1 knockout disrupt barrier function? | CLDN1 knockout Sertoli cells |
| Does SLC15A1 mediate peptide drug uptake? | SLC15A1 knockout intestinal cells |
How to Study the transepithelial transport Process
| Method | What It Measures | Typical Application |
|---|---|---|
| TEER | Barrier integrity | Caco-2 and Sertoli cell monolayers [1,4] |
| FITC-dextran permeability | Paracellular flux | Epithelial barrier assays |
| Radiolabeled substrate flux | Directed transport | Glucose and ion transport [3,6] |
| Fluorescent drug transport | Transporter-mediated uptake/efflux | Caco-2 drug transport [4,8] |
| Live-cell imaging | Vesicular trafficking | Transporter recycling [5,7] |
| CRISPR knockout | Gene function | Causal dissection of transport genes [4,8] |
| CRISPR knock-in | Tagged protein localization | Aquaporin and transporter imaging |
| Overexpression | Gain-of-function transport | Efflux transporter studies |
Transepithelial electrical resistance and permeability assays
Transepithelial electrical resistance (TEER) and paracellular permeability assays using tracers such as FITC-dextran are standard methods to assess epithelial barrier integrity and transport function [1,4]. These assays are commonly performed in Caco-2 and MDCK monolayers and in Sertoli cell cultures [1,4].
Transport assays with radiolabeled or fluorescent substrates
Directed transport of glucose, ions, drugs, and xenobiotics can be measured using radiolabeled or fluorescent substrates in polarized epithelial monolayers [3,4,8]. Apical-to-basolateral and basolateral-to-apical fluxes reveal net vectorial transport and transporter involvement [4,8].
Imaging and vesicular trafficking analysis
Fluorescence imaging of tagged transporters and aquaporins allows visualization of apical and basolateral localization and vesicular recycling [5,7]. Live-cell imaging can capture dynamic insertion and retrieval events that regulate transport capacity.
CRISPR-based genetic dissection
CRISPR knockout, point mutation, knock-in, and overexpression models enable causal testing of candidate genes in transepithelial transport [4,8]. These approaches can be combined with transport assays to link genotype to function [4,8].
How CRISPR Can Be Used to Study GO:0070633 transepithelial transport
Knockout
CRISPR knockout of transepithelial transport genes such as SLC5A1, CFTR, or CLDN1 allows researchers to test loss-of-function effects on substrate flux and barrier integrity [1,2,3]. Knockout Caco-2 and Sertoli cell models are widely used to link specific genes to transport phenotypes [1,4].
Point Mutation
Point mutations can model disease-associated variants in transporters and channels, such as CFTR mutations that alter ductal ion transport. These models help distinguish loss-of-function, gain-of-function, and trafficking defects.
Knock-in
Knock-in of fluorescent or epitope tags into genes such as AQP5 or SLC2A1 enables real-time tracking of protein localization and vesicular trafficking in polarized epithelia [5,7]. Tagged knock-in models preserve endogenous regulatory sequences.
Overexpression
Overexpression of efflux transporters such as ABCB1 or ABCG2 in Caco-2 cells increases transport capacity and can model drug resistance or altered pharmacokinetics. Overexpression studies complement knockout approaches by revealing gain-of-function effects.
How EDITGENE Supports transepithelial transport Research
Researchers studying transepithelial transport-related genes often need to determine whether a candidate gene is causally involved in substrate flux, barrier function, or epithelial homeostasis. EDITGENE provides CRISPR-based cell model services that enable precise genetic manipulation of transport genes in relevant epithelial systems.
Contact EDITGENE today to design your custom CRISPR model for transepithelial transport research.
Frequently Asked Questions About transepithelial transport
What is transepithelial transport (GO:0070633)?
Transepithelial transport is the directed movement of a substance from one side of an epithelium to the other, as defined by GO:0070633 [1,2].
What genes are involved in transepithelial transport?
Key genes include SLC5A1, SLC2A1, SLC2A2, AQP1, AQP3, AQP5, CFTR, SLC12A2, ATP1A1, CLDN1, CLDN3, OCLN, TJP1, ABCB1, ABCG2, SLC22A1, SLC15A1, and TRPV6 [1,2,3,4,6,7,8].
How is transepithelial transport regulated?
It is regulated by vesicular trafficking, hormones, neural signals, and tight junction modulation [1,2,5].
What is the role of aquaporins in transepithelial transport?
Aquaporins such as AQP1, AQP3, and AQP5 facilitate water movement across epithelial membranes.
How do glucose transporters mediate transepithelial transport?
SGLT1 mediates apical Na+-dependent glucose uptake, while GLUT1 and GLUT2 mediate basolateral exit [3,6].
What diseases are linked to transepithelial transport defects?
Defects are linked to male infertility, salivary gland dysfunction, intestinal malabsorption, and altered drug pharmacokinetics [1,2,3,4].
How can I study transepithelial transport in the lab?
Common methods include TEER, permeability assays, radiolabeled substrate flux, imaging, and CRISPR-based genetic models [1,4,5,8].
What cell models are used for transepithelial transport research?
Caco-2, MDCK, Sertoli cell cultures, and salivary duct cell models are widely used [1,2,4,8].
Can CRISPR knockout help identify transepithelial transport genes?
Yes, CRISPR knockout of candidate genes followed by transport assays can establish causal roles in transepithelial transport [4,8].
What is the difference between transcellular and paracellular transport?
Transcellular transport moves substances through cells via apical and basolateral transporters, while paracellular transport moves substances between cells through tight junctions [1,5].
Conclusion
Transepithelial transport (GO:0070633) is a fundamental biological process that governs the vectorial movement of ions, nutrients, water, drugs, and xenobiotics across epithelial barriers [1,2,3]. Its molecular basis involves polarized transporters, channels, aquaporins, and tight junction proteins, with dynamic regulation by vesicular trafficking and signaling pathways [5,6,7]. Dysregulation of this process contributes to male infertility, salivary gland dysfunction, intestinal disorders, and altered drug disposition [1,2,4]. CRISPR-based cell models provide powerful tools to dissect the causal roles of individual genes in transepithelial transport and to accelerate therapeutic discovery [4,8].
References
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- 3. Takata K. 1998. [Transepithelial transport of glucose].. Kaibogaku Zasshi 73(5):485-95 PMID: 9844339
- 4. Liu Y et al.. 2025. Transepithelial transport and mechanism of pyrethroids across Caco-2 cells mediated by transporters.. Pestic Biochem Physiol 212:106456 PMID: 40500064
- 5. Park CS et al.. 2000. Vesicular transport as a new paradigm in short-term regulation of transepithelial transport.. J Korean Med Sci 15(2):123-32 PMID: 10803686
- 6. Takata K. 1996. Glucose transporters in the transepithelial transport of glucose.. J Electron Microsc (Tokyo) 45(4):275-84 PMID: 8888584
- 7. Geng X et al.. 2017. Transport Characteristics of Aquaporins.. Adv Exp Med Biol 969:51-62 PMID: 28258565
- 8. Chen Y et al.. 2019. Transepithelial transport mechanisms of 7,8-dihydroxyflavone, a small molecular TrkB receptor agonist, in human intestinal Caco-2 cells.. Food Funct 10(8):5215-5227 PMID: 31384856
