GO:0048549 positive regulation of pinocytosis: Cellular Uptake Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0048549 (positive regulation of pinocytosis) describes any process that activates, maintains, or increases the rate of pinocytosis, the 'cell drinking' mechanism by which cells internalize extracellular fluid and its contents in vesicles.
• Pinocytosis is distinct from phagocytosis and is constitutively active in many cell types, but its rate can be strongly upregulated by growth factors, nutrients, and pathogens [3, 4].
• Key molecular drivers include CDC42, PI3K/AKT signaling, SNX5, and the actin cytoskeleton, which coordinate membrane ruffling and vesicle formation [1, 4, 5].
• Dysregulated pinocytosis contributes to viral entry (e.g., HBV via NTCP), cancer drug resistance (e.g., sorafenib resistance in HCC), and immune cell function [1, 2, 7].
• CRISPR knockout, point-mutation, knock-in, and overexpression models are essential to dissect causal roles of specific genes in pinocytosis regulation [4, 8].
• EDITGENE provides end-to-end CRISPR services, including library screening and bioinformatics, to accelerate research on pinocytosis-related pathways.
Description
Positive regulation of pinocytosis (GO:0048549) is a biological process that encompasses any mechanism which activates, maintains, or increases the rate of pinocytosis, a form of endocytosis in which cells internalize extracellular fluid and dissolved solutes through plasma membrane invagination. This process is fundamental for nutrient uptake, antigen sampling, and cellular homeostasis, and it is distinct from receptor-mediated endocytosis and phagocytosis [3, 4]. Understanding how pinocytosis is positively regulated is critical because its dysregulation is implicated in viral entry, cancer progression, and immune responses [1, 2, 7]. For researchers, GO:0048549 provides a framework to study the signaling cascades, cytoskeletal rearrangements, and vesicle trafficking events that control this uptake pathway [3, 5]. The term is particularly relevant in immunology, oncology, and infectious disease research, where modulating pinocytosis can alter disease outcomes [1, 2, 7]. This article synthesizes authoritative QuickGO data and verified PubMed literature to provide a research-grade overview of the genes, mechanisms, and experimental models associated with positive regulation of pinocytosis.
positive regulation of pinocytosis At A Glance
| GO ID | GO:0048549 |
|---|---|
| GO term | positive regulation of pinocytosis |
| Ontology | biological_process |
| Synonym | activation of pinocytosis; stimulation of pinocytosis; up regulation of pinocytosis; up-regulation of pinocytosis; upregulation of pinocytosis |
| Major function | Increases the rate of fluid-phase uptake via plasma membrane invagination and vesicle formation |
| Related process | Pinocytosis (GO:0006907); regulation of pinocytosis (GO:0048548) |
| Cellular location | Plasma membrane, endosomes, actin cytoskeleton |
| Key regulators | CDC42, PI3K/AKT, SNX5, WNK/SGK1 pathway |
What Is GO:0048549?
According to the Gene Ontology, positive regulation of pinocytosis (GO:0048549) is defined as any process that activates, maintains, or increases the rate of pinocytosis. Pinocytosis, literally 'cell drinking', is the process by which cells take in liquid material from their external environment. The liquid is enclosed in vesicles formed by invagination of the plasma membrane; these vesicles then move into the cell and pass their contents to endosomes. This term is a biological process and includes synonyms such as activation of pinocytosis, stimulation of pinocytosis, up regulation of pinocytosis, up-regulation of pinocytosis, and upregulation of pinocytosis.
Why Is positive regulation of pinocytosis Important in Cell Biology?
Positive regulation of pinocytosis is important because it controls the uptake of nutrients, antigens, and pathogens, and its dysregulation is linked to major human diseases including cancer, viral infections, and immune disorders [1, 2, 7]. For example, CDC42 supports hepatitis B virus entry by promoting NTCP translocation and macropinocytosis, a form of pinocytosis. In hepatocellular carcinoma, CD147-positive migrasome macropinocytosis promotes sorafenib resistance via PI3K/AKT/TWIST1 signaling. Additionally, Akt3 kinase suppresses pinocytosis of low-density lipoprotein in macrophages through a WNK/SGK1/Cdc42 pathway, highlighting the intricate regulation of this process. Understanding these mechanisms can reveal therapeutic targets for antiviral and anticancer strategies.
• Pinocytosis is a major route for nutrient uptake and antigen sampling in immune cells [3, 7].
• Positive regulation of pinocytosis facilitates viral entry, as shown for HBV via CDC42-mediated NTCP translocation.
• Enhanced pinocytosis contributes to chemoresistance in hepatocellular carcinoma through CD147-positive migrasomes.
• Akt3 kinase negatively regulates pinocytosis of LDL in macrophages, linking this process to atherosclerosis.
• SNX5 is required for macropinocytosis, a related process, and its loss impairs membrane ruffling.
• B cells use pinocytosis for antigen presentation, and bacterial pathogens can exploit this for infection.
• Rai14 interacts with invariant chain to regulate macropinocytosis, affecting antigen presentation.
• mTORC1 signaling is modulated by macropinocytosis, connecting nutrient uptake to cell growth control.
• Dysregulated pinocytosis can lead to uncontrolled uptake of drugs, affecting therapeutic efficacy.
• CRISPR-based models enable precise dissection of genes controlling pinocytosis for drug discovery [4, 8].
What Happens During positive regulation of pinocytosis?
Initiation and Membrane Ruffling
In simple terms: The cell starts to form small waves or ruffles on its surface to take in fluid.
Positive regulation of pinocytosis begins with signaling events that trigger actin cytoskeleton rearrangements, leading to membrane ruffling. CDC42, a Rho family GTPase, is a key regulator that promotes actin polymerization and membrane protrusions [1, 4]. In the context of HBV entry, CDC42 supports NTCP translocation to the plasma membrane and macropinocytosis, facilitating viral internalization. Similarly, SNX5 is required for macropinocytosis, and its depletion impairs membrane ruffling and vesicle formation.
Vesicle Formation and Scission
In simple terms: The ruffled membrane folds back and pinches off to create a bubble filled with fluid.
Following membrane ruffling, the plasma membrane invaginates and pinches off to form pinocytic vesicles. This step requires coordinated action of actin and BAR-domain proteins. SNX5, a sorting nexin, regulates macropinocytosis by controlling membrane curvature and scission. The WNK/SGK1/Cdc42 pathway also modulates vesicle formation, as Akt3 kinase suppresses pinocytosis of LDL by macrophages through this pathway.
Vesicle Trafficking and Endosomal Fusion
In simple terms: The fluid-filled bubble travels into the cell and merges with other compartments to deliver its contents.
After formation, pinocytic vesicles move into the cell and fuse with endosomes, delivering their contents for processing. This trafficking is regulated by Rab GTPases and SNARE proteins. In antigen-presenting cells, Rai14 interacts with invariant chain to regulate macropinocytosis and subsequent antigen presentation. The mTORC1 pathway senses nutrients delivered by macropinocytosis, linking uptake to cell growth control.
Signaling Pathways That Positively Regulate Pinocytosis
In simple terms: Various signals tell the cell to drink more or less.
Multiple signaling pathways positively regulate pinocytosis. PI3K/AKT signaling promotes macropinocytosis in cancer cells, as seen in CD147-positive migrasome macropinocytosis driving sorafenib resistance in HCC. Conversely, Akt3 kinase suppresses pinocytosis of LDL in macrophages via the WNK/SGK1/Cdc42 pathway, indicating isoform-specific regulation. Growth factors and nutrients can also stimulate pinocytosis through mTORC1.
Physiological Outcomes and Pathological Hijacking
In simple terms: Drinking too much or too little can cause problems, and some germs take advantage of this process.
Physiologically, positive regulation of pinocytosis supports nutrient uptake, immune surveillance, and clearance of extracellular fluid [3, 7]. Pathologically, viruses such as HBV exploit CDC42-mediated macropinocytosis for entry, and cancer cells use macropinocytosis to survive under nutrient stress and resist drugs. B cells can be targeted by bacterial pathogens that exploit pinocytosis for infection.
Key Genes Involved in GO:0048549 positive regulation of pinocytosis
The following genes and proteins have been experimentally implicated in the positive regulation of pinocytosis or related macropinocytosis, based on verified PubMed literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| CDC42 | Promotes actin polymerization and membrane ruffling for macropinocytosis | Supports HBV entry via NTCP translocation; target for antiviral research |
| PIK3CA | Catalytic subunit of PI3K; activates AKT signaling | Drives macropinocytosis in cancer; linked to sorafenib resistance |
| AKT1 | Serine/threonine kinase; promotes cell survival and macropinocytosis | Mediates PI3K/AKT/TWIST1 signaling in HCC |
| AKT3 | Kinase that suppresses pinocytosis of LDL in macrophages | Regulates WNK/SGK1/Cdc42 pathway; atherosclerosis research |
| SNX5 | Sorting nexin; regulates membrane curvature and macropinocytosis | Required for macropinocytosis; knockout impairs ruffling |
| WNK1 | Kinase upstream of SGK1; modulates Cdc42 activity | Part of Akt3-WNK-SGK1-Cdc42 pathway |
| SGK1 | Serum/glucocorticoid-regulated kinase; regulates ion channels and Cdc42 | Involved in pinocytosis suppression by Akt3 |
| Rai14 | Ankyrin repeat protein; interacts with invariant chain | Regulates macropinocytosis in antigen-presenting cells |
| CD147 | Basigin; induces migrasome formation | Promotes macropinocytosis in HCC for drug resistance |
| TWIST1 | Transcription factor; induces epithelial-mesenchymal transition | Downstream of PI3K/AKT in HCC macropinocytosis |
| NTCP | Sodium taurocholate cotransporting polypeptide; HBV receptor | Translocated by CDC42 to plasma membrane for viral entry |
| Fgr | Src family kinase; negative regulator of phagocytosis | May influence related uptake processes in macrophages |
| mTOR | Kinase; central regulator of cell growth | Senses nutrients from macropinocytosis; links to mTORC1 |
| RAC1 | Rho GTPase; regulates actin dynamics | Potential regulator of macropinocytosis (implied by related pathways) |
| ARF6 | Small GTPase; regulates endosomal recycling | May modulate pinocytosis (implied by endocytic pathways) |
| Rab5 | GTPase; regulates early endosome fusion | Involved in vesicle trafficking after pinocytosis |
| Rab7 | GTPase; regulates late endosome/lysosome fusion | Mediates degradation of pinocytosed contents |
| Clathrin | Coat protein; mediates receptor-mediated endocytosis | Distinct from pinocytosis but may overlap in some cells |
How Is positive regulation of pinocytosis Regulated?
Positive regulation of pinocytosis is controlled by a complex network of signaling pathways. The PI3K/AKT pathway promotes macropinocytosis in cancer cells, as demonstrated by CD147-positive migrasome macropinocytosis driving sorafenib resistance via PI3K/AKT/TWIST1 signaling. Conversely, Akt3 kinase suppresses pinocytosis of LDL in macrophages through a WNK/SGK1/Cdc42 pathway, highlighting isoform-specific negative regulation. mTORC1 acts as a sensor of nutrients internalized by macropinocytosis, linking uptake to cell growth control. Additionally, SNX5 is required for macropinocytosis, and its loss impairs membrane ruffling. These regulatory mechanisms are potential therapeutic targets for modulating pinocytosis in disease.
positive regulation of pinocytosis and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| CDC42 | HBV infection | Knockout of CDC42 in hepatocytes to assess NTCP translocation and viral entry |
| CD147 | HCC sorafenib resistance | Overexpression of CD147 in HCC cell lines to study macropinocytosis and drug resistance |
| AKT3 | Atherosclerosis | Knockout of Akt3 in macrophages to measure LDL pinocytosis |
| SNX5 | Macropinocytosis defect | SNX5 knockout cells to evaluate membrane ruffling and uptake |
| Rai14 | Antigen presentation | Rai14 knockout in antigen-presenting cells to assess macropinocytosis |
Viral Infection and HBV Entry
Positive regulation of pinocytosis can be hijacked by viruses for entry. CDC42 supports hepatitis B virus (HBV) entry by promoting NTCP translocation to the plasma membrane and macropinocytosis. This highlights how viruses exploit cellular drinking mechanisms, and targeting CDC42 or NTCP may offer antiviral strategies.
Cancer Drug Resistance and Metastasis
In hepatocellular carcinoma (HCC), CD147-positive migrasome macropinocytosis promotes sorafenib resistance via PI3K/AKT/TWIST1 signaling. This indicates that upregulated pinocytosis can confer chemoresistance and drive vasculogenic mimicry, making it a potential target for overcoming drug resistance.
Atherosclerosis and Macrophage Function
Akt3 kinase suppresses pinocytosis of low-density lipoprotein (LDL) by macrophages via a WNK/SGK1/Cdc42 pathway. Dysregulation of this process may contribute to foam cell formation and atherosclerosis, suggesting that modulating pinocytosis could affect cardiovascular disease.
Immune Response and Bacterial Infection
B cells use pinocytosis for antigen sampling, and bacterial pathogens can exploit this process for infection. Rai14 interacts with invariant chain to regulate macropinocytosis, affecting antigen presentation. Thus, positive regulation of pinocytosis is critical in immunity and host-pathogen interactions.
From positive regulation of pinocytosis-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does gene X regulate pinocytosis? | CRISPR knockout of gene X in relevant cell line, followed by fluid-phase uptake assay |
| Does a specific mutation in gene X affect pinocytosis? | Point-mutation knock-in of the mutation using CRISPR |
| Does tagging gene X affect its function in pinocytosis? | Tagged knock-in (e.g., GFP) to visualize localization |
| Does overexpression of gene X enhance pinocytosis? | Overexpression via lentiviral transduction or CRISPR activation |
| Which genes are essential for pinocytosis? | Genome-wide CRISPR library screening with a fluorescent fluid-phase marker |
| How does gene X affect signaling during pinocytosis? | Phosphoproteomics or RNA-seq after knockout/overexpression |
How to Study the positive regulation of pinocytosis Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Fluid-phase uptake assay | Rate of pinocytosis | Quantify effects of gene knockout or overexpression |
| Live-cell imaging | Membrane dynamics and vesicle trafficking | Visualize CDC42 localization during macropinocytosis |
| CRISPR knockout screening | Genes essential for pinocytosis | Identify novel regulators in a cell line |
| Phosphoproteomics | Signaling changes | Map PI3K/AKT pathway activation |
| RNA-seq | Transcriptional changes | Assess gene expression after perturbation |
| Proximity ligation assay | Protein-protein interactions | Detect Rai14-invariant chain interaction |
| Flow cytometry | Cell surface receptor levels | Measure NTCP translocation |
| Western blot | Protein expression and phosphorylation | Validate knockout efficiency and signaling |
Fluid-Phase Uptake Assays
Fluid-phase uptake assays using fluorescent dextran or Lucifer Yellow are standard to measure pinocytosis. Cells are incubated with the marker, washed, and analyzed by flow cytometry or microscopy. This method can quantify the rate of pinocytosis and assess the effect of genetic perturbations [4, 5].
Live-Cell Imaging and Microscopy
Live-cell imaging with fluorescently tagged proteins (e.g., GFP-CDC42) allows visualization of membrane ruffling, vesicle formation, and trafficking. Total internal reflection fluorescence (TIRF) microscopy is particularly useful to study events at the plasma membrane [1, 5].
CRISPR Screening and Bioinformatics
Genome-wide CRISPR knockout or activation screens coupled with fluid-phase uptake readouts can identify novel regulators of pinocytosis. Bioinformatics analysis of screen hits, such as pathway enrichment and network analysis, helps prioritize candidate genes for validation.
Proteomics and Phosphoproteomics
Mass spectrometry-based proteomics can identify proteins associated with pinocytic vesicles or changes in signaling upon stimulation. Phosphoproteomics reveals kinase pathways (e.g., PI3K/AKT) activated during positive regulation of pinocytosis [2, 4].
How CRISPR Can Be Used to Study GO:0048549 positive regulation of pinocytosis
Knockout
CRISPR knockout is used to delete genes such as CDC42, SNX5, or Akt3 to determine their causal role in positive regulation of pinocytosis. For example, SNX5 knockout impairs macropinocytosis, demonstrating its requirement. Knockout models are essential for loss-of-function studies.
Point Mutation
Point mutations can be introduced to mimic disease-associated variants or to abrogate specific phosphorylation sites. For instance, mutating the GTP-binding domain of CDC42 can clarify its role in NTCP translocation and HBV entry. Point-mutation knock-in models provide precise mechanistic insights.
Knock-in
Knock-in of tagged versions (e.g., GFP, HA) allows visualization and immunoprecipitation of proteins like SNX5 or Rai14. This helps track localization and interactions during pinocytosis [5, 8]. Knock-in of reporter genes can also monitor pathway activity.
Overexpression
Overexpression of genes such as CD147 or constitutively active AKT1 can enhance pinocytosis and drive phenotypes like drug resistance. Overexpression models are useful for gain-of-function studies and for validating oncogenic roles.
How EDITGENE Supports positive regulation of pinocytosis Research
Researchers studying positive regulation of pinocytosis-related genes often need to determine whether a candidate gene is causally involved in this process or merely correlated. EDITGENE provides comprehensive CRISPR services to generate knockout, point-mutation, knock-in, and overexpression cell models, as well as library screening and bioinformatics support, enabling rigorous functional validation.
Contact EDITGENE today to design your custom CRISPR model for positive regulation of pinocytosis research.
Frequently Asked Questions About positive regulation of pinocytosis
What is positive regulation of pinocytosis (GO:0048549)?
It is any process that activates, maintains, or increases the rate of pinocytosis, a form of endocytosis where cells internalize extracellular fluid in vesicles.
What genes are involved in positive regulation of pinocytosis?
Key genes include CDC42, PI3K/AKT pathway components, SNX5, and Rai14, among others [1, 2, 4, 5, 8].
How is pinocytosis different from phagocytosis?
Pinocytosis is the uptake of fluid and solutes, while phagocytosis is the ingestion of large particles like bacteria. They are distinct processes with different molecular regulators [3, 6].
What diseases are associated with dysregulated pinocytosis?
Diseases include viral infections (e.g., HBV), cancer drug resistance (e.g., HCC), and atherosclerosis, as well as immune disorders [1, 2, 4, 7].
How can I study positive regulation of pinocytosis in the lab?
Common methods include fluid-phase uptake assays, live-cell imaging, CRISPR knockout, and proteomics [4, 5].
What is the role of CDC42 in pinocytosis?
CDC42 promotes actin polymerization and membrane ruffling, facilitating macropinocytosis and viral entry [1, 4].
Does mTOR regulate pinocytosis?
Yes, mTORC1 senses nutrients internalized by macropinocytosis and links uptake to cell growth control.
What is the role of SNX5 in macropinocytosis?
SNX5 is required for macropinocytosis; its depletion impairs membrane ruffling and vesicle formation.
How does Akt3 affect pinocytosis?
Akt3 kinase suppresses pinocytosis of LDL in macrophages via a WNK/SGK1/Cdc42 pathway.
Can CRISPR be used to study pinocytosis?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models are powerful tools to dissect gene function in pinocytosis [4, 5, 8].
Conclusion
Positive regulation of pinocytosis (GO:0048549) is a critical biological process that controls cellular fluid uptake and is implicated in viral infection, cancer, and immune responses. Key regulators such as CDC42, PI3K/AKT, SNX5, and Rai14 have been identified through rigorous studies [1, 2, 4, 5, 8]. Understanding these mechanisms offers opportunities for therapeutic intervention. EDITGENE provides comprehensive CRISPR services to facilitate functional studies and accelerate discovery in this field.
References
- 1. Cui S et al.. 2025. CDC42 supports HBV entry by NTCP translocation to the plasma membrane and macropinocytosis.. EMBO Rep 26(21):5239-5269 PMID: 40954218
- 2. Qian L et al.. 2026. CD147-positive migrasome macropinocytosis promotes HCC sorafenib resistance via inducing vasculogenic mimicry triggered by PI3K/AKT/TWIST1 signaling.. Cell Death Dis 17(1) PMID: 42297770
- 3. Yoshida S et al.. 2018. Macropinocytosis, mTORC1 and cellular growth control.. Cell Mol Life Sci 75(7):1227-1239 PMID: 29119228
- 4. Ding L et al.. 2017. Akt3 kinase suppresses pinocytosis of low-density lipoprotein by macrophages via a novel WNK/SGK1/Cdc42 protein pathway.. J Biol Chem 292(22):9283-9293 PMID: 28389565
- 5. Lim JP et al.. 2008. A role for SNX5 in the regulation of macropinocytosis.. BMC Cell Biol 9:58 PMID: 18854019
- 6. Gresham HD et al.. 2000. Negative regulation of phagocytosis in murine macrophages by the Src kinase family member, Fgr.. J Exp Med 191(3):515-28 PMID: 10662797
- 7. García-Gil A et al.. 2019. Beyond the antibody: B cells as a target for bacterial infection.. J Leukoc Biol 105(5):905-913 PMID: 30657607
- 8. Lobos Patorniti N et al.. 2023. Rai14 is a novel interactor of Invariant chain that regulates macropinocytosis.. Front Immunol 14:1182180 PMID: 37545539
