Table 1.
Agent | Mechanism Affected 1 | Effect | Limitation | Ref. |
---|---|---|---|---|
Low temp (4 degrees) | All energy dependent processes | Slows down/inhibits all energy dependent processes | Low temperature may influence fluidity of cell membrane | [47,48] |
Sodium azide | All energy dependent processes | Inhibits respiratory system of cells | Toxic at higher concentrations | [49,50] |
Chlorpromazine | CME | Translocates clathrin and AP2 from the cell surface to intracellular endosomes | Not efficient in all cell lines, might interfere with the biogenesis of intracellular vesicles | [51,52,53] [54] (pp. 19–20) |
Cytosol acidification | CME | Inhibits the budding-off of clathrin- coated pits from the membrane | Interferes with macropinocytosis and the actin cytoskeleton | [54] (p. 19) |
Hypertonic sucrose | CME | Removes plasma membrane-associated clathrin lattices | Nonspecific, interferes with fluid phase macropinocytosis | [54] (pp. 17–18) [55,56] |
Monodansylcadaverine | CME | Stabilizes clathrin-coated pits | Induces global changes in actin dynamics | [54] (p. 20) |
Phenylarsine oxide | CME | Mechanisms unknown, possibly a tyrosine phosphate inhibitor | Also inhibits micropinocytosis and is toxic at higher concentrations | [57,58] |
Potassium depletion | CME | Removes plasma membrane-associated clathrin lattices | Nonspecific; affects actin cytoskeleton | [54] (p. 18) [59] |
Dynasore | CME, CvME | Inhibitor of dynamin (small GTPase) | Has other off-target effects, including inhibition of membrane ruffling | [60,61] |
Genistein | CvME | Inhibitor of several tyrosine kinases, causes disruption of the actin network | Affects several uptake processes | [62,63] |
Okadaic acid | CvME | Phosphatase inhibitor, stimulates trafficking and internalization of caveolae | Nonspecific, off-target effects | [64] |
Cholesterol inhibitors | ||||
Filipin | CvME, Lipid raft | Binds to cholesterol in the membrane | Unstable and toxic, cholesterol influences other endocytic pathways besides CvME | [54] (pp. 23–24) [65,66] |
Statins | CvME, Lipid raft | Lowering of cholesterol formation by inhibiting the enzyme 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase | Nonspecific, many off-target effects | [54] (p. 22) [67,68] |
Methyl-β-cyclodextrin | CvME, Lipid raft | Removes cholesterol out of the plasma membrane by forming soluble inclusion complexes with cholesterol | Nonspecific, interferes with fluid phase endocytosis and CME, might induce membrane curvature | [54] (pp. 22–23) [69,70] |
Nystatin | CvME, Lipid raft | Binds to cholesterol in the membrane | Toxic | [54] (pp. 23–24) |
(Endosome) acidification inhibitors | ||||
Monensin | Prevents acidification of endosomes | Acts as an ionophor, thereby inhibiting the acidification of endosomes | [71,72,73] | |
Nigericin | Prevents acidification of endosomes | Acts as an ionophor, thereby inhibiting the acidification of endosomes | [74,75] | |
Bafilomycin A1 | Prevents acidification of endosomes | Inhibits the vacuolar ATPase endosomal proton pump. | Prevents maturation of autophagic vacuoles by inhibiting fusion between autophagosomes and lysosomes. Potentially inhibits Ca2+ pump SERCA | [76,77,78] |
Chloroquine | Prevents acidification of endosomes | Increases pH of acidic vesicles (e.g., lysosomes), possibly inhibits some lysosomal hydrolases | Affects many other cellular processes | [79,80] (pp. 49–54) |
Amiloride | Macropinocytosis | Inhibits macropinocytosis by lowering submembranous pH (cytosolic pH close to the membrane) and prevents Rac1 and Cdc42 signaling. | [81,82,83] | |
F-actin inhibitors | ||||
Cytochalasin D | Macropinocytosis | Inhibits actin polymerization and may thus lead to actin filament disassembly | Nonspecific, may affect other endocytic processes | [54] (p. 26) [84,85] |
Jasplakinolide | Macropinocytosis | Stabilizes actin and promotes actin assembly | Various effects depending on cell line and assay conditions | [84,86] |
Latrunculin | Macropinocytosis | Sequesters actin monomers, blocks actin polymerization and may thus lead to actin filament disassembly | Not necessarily efficient in adherent cells | [54] (p. 26) [87,88] |
Swinholide A | Macropinocytosis | Has F-actin severing activity | Nonspecific, may affect other endocytic processes | [86,89] |
Phosphoinositide 3-kinase inhibitors | ||||
LY294002 | Macropinocytosis | Inhibits phosphatidylinositol 3-kinase class I and III | Nonspecific, also affects CME and CvME | [54] (pp. 26–27) [90,91] |
Wortmannin | Macropinocytosis | Inhibits phosphatidylinositol 3-kinase class I and III | Nonspecific, also affects CME and CvME | [54] (pp. 26–27) [90,91] |
3-methyladenine | Macropinocytosis | Inhibits phosphatidylinositol 3-kinase class III | Nonspecific, also affects CME and CvME | [54] (pp. 26–27) [92] |
1 Abbreviations: Clathrin-mediated endocytosis (CME), Caveolae-mediated endocytosis (CvME).