GO:0150104 transport across blood-brain barrier: Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0150104 (transport across blood-brain barrier) describes the directed movement of substances such as macromolecules, small molecules, and ions through the blood-brain barrier (BBB).
• The BBB is a selective interface formed by brain microvascular endothelial cells, supported by pericytes and astrocytes, that controls the exchange of molecules between blood and brain.
• Transport across the BBB occurs via multiple routes, including carrier-mediated transport, receptor-mediated transcytosis, adsorptive transcytosis, and efflux pump activity.
• Key proteins involved include transferrin receptor (TFRC), insulin receptor (INSR), LRP1, P-glycoprotein (ABCB1), GLUT1 (SLC2A1), and LAT1 (SLC7A5).
• Dysregulation of BBB transport is implicated in neurodegenerative diseases, brain tumors, and aging-related cognitive decline.
• Experimental approaches to study BBB transport include in vitro BBB models, in vivo imaging, and CRISPR-based genetic manipulation of transport-related genes.
Description
The blood-brain barrier (BBB) is a highly specialized interface that separates the circulating blood from the brain extracellular fluid, tightly regulating the passage of ions, nutrients, and therapeutic agents. The Gene Ontology term GO:0150104, transport across blood-brain barrier, captures the directed movement of substances through this barrier, a process essential for brain homeostasis and drug delivery. Understanding the molecular mechanisms of BBB transport is critical for developing therapies for neurological disorders, as more than 98% of small-molecule drugs and nearly all large-molecule therapeutics fail to cross the BBB. Transport across the BBB is not a passive process; it relies on a complex interplay of tight junctions, transporters, and vesicular trafficking pathways. The BBB is formed by brain microvascular endothelial cells (BMECs) that are supported by pericytes and astrocyte end-feet, creating a dynamic and selective barrier. This barrier ensures that essential nutrients such as glucose and amino acids reach the brain while excluding potentially harmful xenobiotics and pathogens. Research into GO:0150104 has accelerated due to advances in in vitro BBB models, imaging techniques, and genetic tools such as CRISPR-Cas9. These approaches allow researchers to dissect the specific contributions of individual transporters and receptors to BBB permeability, paving the way for targeted drug delivery strategies and a deeper understanding of neurological disease mechanisms.
transport across blood-brain barrier At A Glance
| GO ID | GO:0150104 |
|---|---|
| GO term | transport across blood-brain barrier |
| Ontology | biological_process |
| Synonym | transport across BBB, transport across blood brain barrier |
| Major function | Directed movement of substances through the blood-brain barrier |
| Related cellular component | Blood-brain barrier (endothelial cells, tight junctions, pericytes, astrocytes) |
| Related molecular functions | Transporter activity, receptor binding, endocytosis, transcytosis |
| Associated diseases | Neurodegenerative disorders, brain tumors, aging-related cognitive decline |
| Research methods | In vitro BBB models, in vivo imaging, CRISPR screens, proteomics |
What Is GO:0150104?
GO:0150104, transport across blood-brain barrier, is defined as the directed movement of substances (e.g., macromolecules, small molecules, ions) through the blood-brain barrier. This biological process encompasses all mechanisms by which molecules traverse the BBB, including passive diffusion, carrier-mediated transport, receptor-mediated transcytosis, and efflux transport.
Why Is transport across blood-brain barrier Important in Cell Biology?
Transport across the blood-brain barrier (GO:0150104) is fundamental to brain physiology, as it governs the delivery of nutrients, hormones, and therapeutic drugs to the central nervous system while protecting the brain from toxins and pathogens. Dysregulation of this process contributes to the pathogenesis of numerous neurological disorders, including Alzheimer's disease, Parkinson's disease, and brain cancers. Moreover, the BBB represents a major obstacle for drug development, as most pharmaceuticals cannot cross it efficiently. Therefore, understanding the molecular mechanisms of BBB transport is essential for designing effective brain-targeted therapies and for elucidating disease mechanisms.
• Maintains brain homeostasis by regulating the exchange of ions, nutrients, and metabolites.
• Protects the central nervous system from circulating toxins, pathogens, and xenobiotics.
• Enables the delivery of essential molecules such as glucose, amino acids, and fatty acids to the brain.
• Represents a major challenge for drug delivery to the brain, limiting treatment of neurological diseases.
• Dysregulation is implicated in neurodegenerative diseases, including Alzheimer's and Parkinson's.
• Plays a role in brain tumor progression and chemotherapy resistance.
• Aging alters BBB transport, affecting nutrient supply and cognitive function.
• Targeting BBB transport pathways can enhance therapeutic antibody uptake.
• Carrier-mediated transport influences the brain penetration of drugs of abuse such as nicotine.
• CRISPR-based genetic screens can identify novel regulators of BBB transport.
What Happens During transport across blood-brain barrier?
Paracellular and transcellular routes
In simple terms: Substances can cross the BBB either by squeezing between cells or by passing through them.
Transport across the BBB can occur via paracellular or transcellular pathways. The paracellular route is largely restricted by tight junctions between brain microvascular endothelial cells, which limit the passage of hydrophilic molecules. In contrast, the transcellular route involves the movement of substances through the endothelial cell, often via vesicular transport mechanisms such as receptor-mediated transcytosis. The balance between these routes determines the permeability of the BBB to different classes of molecules.
Carrier-mediated transport
In simple terms: Specialized proteins act like ferries to carry specific molecules across the BBB.
Carrier-mediated transport is a key mechanism for the uptake of essential nutrients such as glucose, amino acids, and vitamins. For example, the glucose transporter GLUT1 (SLC2A1) facilitates the transport of glucose across the BBB. Similarly, the L-type amino acid transporter LAT1 (SLC7A5) mediates the transport of large neutral amino acids and certain drugs, including nicotine. These transporters are saturable and exhibit substrate specificity, which can be exploited for drug delivery.
Receptor-mediated transcytosis
In simple terms: Molecules bind to receptors on the BBB, which then carry them into the brain.
Receptor-mediated transcytosis (RMT) involves the binding of ligands to specific receptors on the luminal surface of brain endothelial cells, followed by internalization and transport across the cell to the abluminal side. Well-characterized RMT targets include the transferrin receptor (TFRC) and the insulin receptor (INSR), which have been exploited for brain delivery of therapeutic antibodies. The discovery of novel BBB targets to enhance brain uptake of antibodies is an active area of research.
Efflux transport
In simple terms: Pumps on the BBB actively push unwanted substances back into the blood.
Efflux transporters such as P-glycoprotein (ABCB1) are ATP-binding cassette (ABC) transporters that actively pump a wide range of substrates, including drugs and xenobiotics, out of the brain. This efflux activity limits the accumulation of many therapeutics in the CNS and contributes to drug resistance. Modulating efflux transporter function is a strategy to improve drug delivery across the BBB.
Vesicular trafficking and regulation
In simple terms: Inside the cell, tiny vesicles carry molecules across the BBB, and this process is tightly controlled.
Intracellular transport and regulation of transcytosis across the BBB involve complex vesicular trafficking machinery, including Rab GTPases and SNARE proteins. The regulation of transcytosis is critical for maintaining BBB integrity and responding to physiological demands. Dysregulation of vesicular trafficking can lead to altered BBB permeability and contribute to disease.
Key Genes Involved in GO:0150104 transport across blood-brain barrier
The following genes encode proteins that are centrally involved in transport across the blood-brain barrier (GO:0150104), as supported by published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| TFRC | Transferrin receptor; mediates receptor-mediated transcytosis of transferrin and therapeutic antibodies | Target for brain drug delivery; studied in antibody engineering |
| INSR | Insulin receptor; facilitates transcytosis of insulin and insulin-like growth factors | Exploited for brain uptake of therapeutic antibodies |
| LRP1 | LDL receptor-related protein 1; mediates transcytosis of various ligands including amyloid-beta | Implicated in Alzheimer's disease and drug delivery |
| ABCB1 | P-glycoprotein; ATP-dependent efflux pump that restricts drug entry into the brain | Major determinant of drug resistance in brain tumors and epilepsy |
| SLC2A1 | GLUT1 glucose transporter; mediates glucose transport across the BBB | Essential for brain energy metabolism; mutations cause GLUT1 deficiency syndrome |
| SLC7A5 | LAT1 amino acid transporter; transports large neutral amino acids and drugs like nicotine | Involved in drug delivery and nicotine addiction |
| SLC16A1 | MCT1 monocarboxylate transporter; transports lactate and pyruvate | Role in brain energy metabolism and drug transport |
| SLC22A8 | OAT3 organic anion transporter; transports organic anions and drugs | Involved in drug disposition and BBB permeability |
| ABCB1B | Mouse ortholog of ABCB1; efflux transporter in rodents | Used in preclinical BBB studies |
| CLDN5 | Claudin-5; tight junction protein critical for BBB integrity | Regulates paracellular permeability |
| OCLN | Occludin; tight junction protein contributing to BBB barrier function | Modulates BBB permeability |
| TJP1 | ZO-1; scaffolding protein linking tight junctions to the cytoskeleton | Essential for BBB assembly and function |
| RAB5A | Rab5; small GTPase regulating early endosome fusion in transcytosis | Involved in vesicular trafficking across BBB |
| RAB11A | Rab11; regulates recycling endosomes in transcytosis | Modulates receptor-mediated transport |
| CAV1 | Caveolin-1; structural protein of caveolae involved in adsorptive transcytosis | Role in BBB transcytosis and signaling |
| VEGFA | Vascular endothelial growth factor A; regulates BBB permeability and angiogenesis | Implicated in BBB breakdown in disease |
| AGER | RAGE; receptor for advanced glycation end products; mediates transcytosis of amyloid-beta | Linked to Alzheimer's disease pathology |
| INS | Insulin; ligand for INSR; influences BBB transport | Studied for brain delivery and metabolic regulation |
How Is transport across blood-brain barrier Regulated?
Transport across the blood-brain barrier is tightly regulated at multiple levels. Transcriptional regulation of transporter genes, such as ABCB1 and SLC2A1, modulates BBB permeability in response to physiological and pathological stimuli. Post-translational modifications, including phosphorylation and ubiquitination, control the activity and trafficking of transporters and receptors. Signaling pathways such as Wnt/beta-catenin and VEGF signaling influence BBB development and maintenance. Additionally, aging and disease can alter the expression and function of BBB transporters, as demonstrated by decreased docosahexaenoic acid transport in aged mice. Understanding these regulatory mechanisms is essential for manipulating BBB transport for therapeutic benefit.
transport across blood-brain barrier and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| ABCB1 | Chemoresistance in brain tumors; drug efflux | Knockout mice or in vitro BBB models with ABCB1 deletion |
| LRP1 | Alzheimer's disease; impaired amyloid-beta clearance | Knock-in mice expressing mutant LRP1 or CRISPR KO in cell lines |
| SLC2A1 | GLUT1 deficiency syndrome; impaired glucose transport | Patient-derived iPSCs or knock-in mice with SLC2A1 mutations |
| TFRC | Drug delivery to brain; receptor-mediated transcytosis | Knock-in mice with humanized TFRC for antibody testing |
| AGER | Alzheimer's disease; RAGE-mediated amyloid-beta transport | Knockout mice or overexpression models |
Neurodegenerative diseases
Dysregulation of transport across the blood-brain barrier is a hallmark of neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). In AD, impaired clearance of amyloid-beta across the BBB contributes to plaque accumulation, and receptors like LRP1 and AGER (RAGE) are critically involved in this process. Aging, a major risk factor for AD, is associated with decreased transport of docosahexaenoic acid (DHA) across the BBB in mice, which may exacerbate cognitive decline. Targeting BBB transport pathways is therefore a promising therapeutic strategy for AD.
Brain tumors
The blood-brain barrier poses a significant obstacle to the delivery of chemotherapeutic agents to brain tumors. Efflux transporters such as P-glycoprotein (ABCB1) actively pump drugs out of the brain, contributing to chemoresistance. Strategies to improve drug transport across the BBB include the development of P-glycoprotein inhibitors and the use of receptor-mediated transcytosis to deliver therapeutics. Understanding the molecular mechanisms of BBB transport in tumors is essential for improving treatment outcomes.
Aging and metabolic disorders
Aging is associated with alterations in BBB transport, including reduced transport of essential nutrients such as DHA, which can impact brain function. Metabolic disorders like diabetes can also affect BBB permeability and transport of insulin and glucose. These changes may contribute to cognitive impairment and neurodegenerative processes. Research into the effects of aging and metabolic stress on BBB transport is critical for developing interventions.
From transport across blood-brain barrier-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does gene X regulate BBB permeability? | CRISPR knockout in brain endothelial cells (bEnd.3) followed by permeability assays |
| What is the role of a specific transporter in drug uptake? | Point mutation knock-in mice altering transporter substrate specificity |
| Can a therapeutic antibody cross the BBB via receptor X? | Knock-in mice expressing human receptor X and in vivo brain uptake studies |
| How does aging affect BBB transport? | Aged mouse models (e.g., C57BL/6J) with transport assays |
| What is the effect of efflux pump overexpression? | Overexpression of ABCB1 in cell-based BBB models |
| Can CRISPR screen identify novel BBB regulators? | Genome-wide CRISPR knockout screen in brain endothelial cells |
How to Study the transport across blood-brain barrier Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Transwell permeability assay | Permeability coefficient of substances across a cell monolayer | In vitro BBB model to study drug transport |
| Confocal imaging | Spatial and temporal distribution of fluorescent substrates | Visualizing xenobiotic transport across BBB |
| PET imaging | Brain uptake of radiolabeled compounds in vivo | Pharmacokinetic studies in animals and humans |
| CRISPR knockout screen | Identification of genes regulating BBB transport | Discovery of novel BBB targets |
| Proteomics | Protein expression and modifications in BBB cells | Characterizing transporter regulation |
| Substrate transport assay | Kinetic parameters of specific transporter-mediated transport | Studying DHA or nicotine transport |
| Antibody brain uptake assay | Concentration of therapeutic antibody in brain | Evaluating receptor-mediated transcytosis |
| Efflux assay | Activity of efflux pumps like P-glycoprotein | Assessing drug resistance |
In vitro BBB models
In vitro BBB models, such as Transwell assays with brain microvascular endothelial cells (BMECs) co-cultured with astrocytes and pericytes, are widely used to study transport across the BBB. These models allow measurement of permeability coefficients for different substances and can be combined with CRISPR gene editing to dissect the role of specific genes. Confocal imaging of xenobiotic transport across the BBB provides spatial and temporal resolution of transport processes.
In vivo imaging and pharmacokinetics
In vivo imaging techniques, including positron emission tomography (PET) and two-photon microscopy, enable real-time assessment of BBB transport in living animals. Pharmacokinetic studies measure brain uptake of drugs by quantifying compound concentrations in brain tissue relative to plasma. These methods are essential for evaluating the efficacy of brain-targeted therapeutics.
Genetic and proteomic approaches
CRISPR-Cas9 screens and RNA interference can identify genes that regulate BBB transport. Proteomic analysis of brain endothelial cells isolated from knockout or knock-in models reveals changes in transporter expression and post-translational modifications. These approaches provide a systems-level understanding of BBB transport mechanisms.
Transport assays for specific substrates
Substrate-specific transport assays, such as those measuring docosahexaenoic acid (DHA) or nicotine transport, are used to quantify the activity of individual transporters. These assays often employ radiolabeled substrates or fluorescent probes and can be performed in vitro or in vivo. They are critical for characterizing the kinetic properties of BBB transporters.
How CRISPR Can Be Used to Study GO:0150104 transport across blood-brain barrier
Knockout
CRISPR-Cas9 knockout of genes involved in BBB transport, such as ABCB1 or SLC2A1, allows researchers to determine their contribution to barrier function and substrate permeability. Knockout models can be generated in brain endothelial cell lines or mice, and the effects on transport can be measured using in vitro and in vivo assays. For example, ABCB1 knockout increases brain accumulation of P-glycoprotein substrates, confirming its role in efflux.
Point Mutation
Point mutations can be introduced into transporter genes to alter substrate specificity or activity without abolishing protein expression. For instance, mutating specific residues in SLC7A5 (LAT1) can change its affinity for nicotine or other substrates, providing insights into structure-function relationships. Such models are valuable for studying the precise molecular determinants of BBB transport.
Knock-in
Knock-in of human genes or reporter tags into the mouse genome can humanize BBB transport targets for drug testing. For example, knocking in human TFRC or INSR allows evaluation of therapeutic antibodies designed for human receptors. Tagged knock-in of transporters with fluorescent proteins enables real-time imaging of their trafficking in brain endothelial cells.
Overexpression
Overexpression of transporters or receptors in cell-based BBB models can enhance the study of transport kinetics and drug delivery. For example, overexpressing ABCB1 in MDCK or bEnd.3 cells increases efflux activity and can be used to screen for P-glycoprotein inhibitors. Overexpression models are also useful for producing large quantities of transporter proteins for structural studies.
How EDITGENE Supports transport across blood-brain barrier Research
Researchers studying transport across blood-brain barrier-related genes often need to determine whether a candidate gene is causally involved in BBB permeability, drug transport, or disease pathogenesis. EDITGENE provides a comprehensive suite of CRISPR-based services to accelerate this research, from gene knockout to precise point mutations and knock-in models.
Contact EDITGENE today to design your custom CRISPR model for transport across blood-brain barrier research.
Frequently Asked Questions About transport across blood-brain barrier
What is GO:0150104?
GO:0150104 is the Gene Ontology term for transport across blood-brain barrier, defined as the directed movement of substances through the blood-brain barrier.
What genes are involved in transport across the blood-brain barrier?
Key genes include TFRC, INSR, LRP1, ABCB1, SLC2A1, SLC7A5, and CLDN5, among others.
How does the blood-brain barrier transport drugs?
Drugs can cross the BBB via carrier-mediated transport, receptor-mediated transcytosis, or passive diffusion, but efflux pumps like P-glycoprotein often limit their entry.
What is receptor-mediated transcytosis?
Receptor-mediated transcytosis is a process where molecules bind to receptors on brain endothelial cells and are transported across the cell into the brain.
Why is the blood-brain barrier important for drug delivery?
The BBB restricts the entry of most drugs into the brain, making it a major challenge for treating neurological diseases.
How is transport across the BBB studied?
Common methods include in vitro Transwell assays, in vivo imaging, pharmacokinetic studies, and CRISPR screens.
What diseases are associated with BBB transport dysfunction?
Neurodegenerative diseases like Alzheimer's, brain tumors, and aging-related cognitive decline are linked to BBB transport dysfunction.
Can CRISPR be used to study BBB transport?
Yes, CRISPR knockout, knock-in, and point mutation models are powerful tools to dissect the role of specific genes in BBB transport.
What is P-glycoprotein's role in the BBB?
P-glycoprotein (ABCB1) is an efflux pump that actively removes drugs and toxins from the brain, contributing to drug resistance.
How does aging affect BBB transport?
Aging can decrease the transport of nutrients like docosahexaenoic acid across the BBB, potentially impacting brain function.
Conclusion
Transport across the blood-brain barrier (GO:0150104) is a vital biological process that maintains brain homeostasis and protects the CNS, while also posing a significant barrier to drug delivery. Advances in CRISPR-based genetic models and imaging technologies are illuminating the molecular players and regulatory mechanisms involved. Understanding these mechanisms is essential for developing therapies for neurological diseases and for enhancing brain-targeted drug delivery. EDITGENE's comprehensive CRISPR services, including knockout, point mutation, knock-in, overexpression, and library screening, empower researchers to dissect BBB transport pathways with precision and accelerate the translation of findings into clinical applications.
References
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- 3. Miller DS. 2003. Confocal imaging of xenobiotic transport across the blood-brain barrier.. J Exp Zool A Comp Exp Biol 300(1):84-90 PMID: 14598390
- 4. Iwao T et al.. 2023. Aging decreases docosahexaenoic acid transport across the blood-brain barrier in C57BL/6J mice.. PLoS One 18(2):e0281946 PMID: 36795730
- 5. Tega Y et al.. 2018. Impact of Nicotine Transport across the Blood-Brain Barrier: Carrier-Mediated Transport of Nicotine and Interaction with Central Nervous System Drugs.. Biol Pharm Bull 41(9):1330-1336 PMID: 30175770
- 6. Bickel U. 2005. How to measure drug transport across the blood-brain barrier.. NeuroRx 2(1):15-26 PMID: 15717054
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- 8. Orthmann A et al.. 2011. Improving the transport of chemotherapeutic drugs across the blood-brain barrier.. Expert Rev Clin Pharmacol 4(4):477-90 PMID: 22114857
