title: Fluorogenic probe for constitutive cellular endocytosis.
abstract: Endocytosis is a fundamental process of eukaryotic cells that is critical for nutrient uptake, signal transduction, and growth. We have developed a molecular probe to quantify endocytosis. The probe is a lipid conjugated to a fluorophore that is masked with an enzyme-activatable moiety known as the trimethyl lock. The probe is not fluorescent when incorporated into the plasma membrane of human cells but becomes fluorescent upon internalization into endosomes, where cellular esterases activate the trimethyl lock. Using this probe, we found that human breast cancer cells undergo constitutive endocytosis more rapidly than do matched noncancerous cells. These data reveal a possible phenotypic distinction of cancer cells that could be the basis for chemotherapeutic intervention.
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA.
authors.forename: Michael N
authors.initials: MN
authors.lastname: Levine
authors.forename: Trish T
authors.initials: TT
authors.lastname: Hoang
authors.forename: Ronald T
authors.initials: RT
authors.lastname: Raines
mesh_terms: D002460:Cell Line; D004705:Endocytosis; D004950:Esterases / Q000378:metabolism; D005452:Fluoresceins / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008856:Microscopy, Fluorescence; D010712:Phosphatidic Acids / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D014508:Urea / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism
chemical_list: D005452:Fluoresceins; D005456:Fluorescent Dyes; D010712:Phosphatidic Acids; D014508:Urea; D004950:Esterases