Niemann-pick type C1 (NPC1) overexpression alters cellular cholesterol homeostasis.
AuthorsMillard EE, Srivastava K, Traub LM, Schaffer JE, Ory DS
JournalJ Biol Chem
PubMed ID10964915
'The Niemann-Pick type C1 (NPC1) protein is a key participant in intracellular trafficking of low density lipoprotein cholesterol, but its role in regulation of sterol homeostasis is not well understood. To characterize further the function of NPC1, we generated stable Chinese hamster ovary (CHO) cell lines overexpressing the human NPC1 ... More
Evidence for trafficking of PfEMP1 to the surface of P. falciparum-infected erythrocytes via a complex membrane network.
AuthorsWickert H, Wissing F, Andrews KT, Stich A, Krohne G, Lanzer M
JournalEur J Cell Biol
PubMed ID12868595
'The human malarial parasite Plasmodium falciparum exports virulence determinants, such as the P. falciparum erythrocyte membrane protein 1 (PfEMP1), beyond its own periplasmatic boundaries to the surface of its host erythrocyte. This is remarkable given that erythrocytes lack a secretory pathway. Here we present evidence for a continuous membrane network ... More
Fluorescence lifetime characterization of novel low-pH probes.
AuthorsLin HJ, Herman P, Kang JS, Lakowicz JR
JournalAnal Biochem
PubMed ID11444806
'The structures and functions of the cellular acidic compartments are strongly dependent on the pH gradients across vesicular membranes. Measurement and imaging of the vesicular pH require fluorophores with appropriate pK(a) values. In this report, we characterized the pH-dependent lifetime responses of a family of acidotropic probes, LysoSensors, to evaluate ... More
Selective perturbation of early endosome and/or trans-Golgi network pH but not lysosome pH by dose-dependent expression of influenza M2 protein.
AuthorsHenkel JR, Popovich JL, Gibson GA, Watkins SC, Weisz OA
JournalJ Biol Chem
PubMed ID10092677
'Many sorting stations along the biosynthetic and endocytic pathways are acidified, suggesting a role for pH regulation in protein traffic. However, the function of acidification in individual compartments has been difficult to examine because global pH perturbants affect all acidified organelles in the cell and also have numerous side effects. ... More
An incremental approach to automated protein localisation.
AuthorsTscherepanow M, Jensen N, Kummert F,
JournalBMC Bioinformatics
PubMed ID18937856
'BACKGROUND: The subcellular localisation of proteins in intact living cells is an important means for gaining information about protein functions. Even dynamic processes can be captured, which can barely be predicted based on amino acid sequences. Besides increasing our knowledge about intracellular processes, this information facilitates the development of innovative ... More
Functional dissection of COP-I subunits in the biogenesis of multivesicular endosomes.
AuthorsGu F, Aniento F, Parton RG, Gruenberg J
JournalJ Cell Biol
PubMed ID9382865
'In the present paper, we show that transport from early to late endosomes is inhibited at the restrictive temperature in a mutant CHO cell line (ldlF) with a ts-defect in epsilon coatomer protein (epsilonCOP), although internalization and recycling continue. Early endosomes then appear like clusters of thin tubules devoid of ... More
Efficient cytosolic delivery of molecular beacon conjugates and flow cytometric analysis of target RNA.
AuthorsChen AK, Behlke MA, Tsourkas A,
JournalNucleic Acids Res
PubMed ID18503086
'Fluorescent microscopy experiments show that when 2''-O-methyl-modified molecular beacons (MBs) are introduced into NIH/3T3 cells, they elicit a nonspecific signal in the nucleus. This false-positive signal can be avoided by conjugating MBs to macromolecules (e.g. NeutrAvidin) that prevent nuclear sequestration, but the presence of a macromolecule makes efficient cytosolic delivery ... More
Fluorescent indicators for intracellular pH.
AuthorsHan J, Burgess K,
JournalChem Rev
PubMed ID19831417
This review is about intracellular pH sensors, includingsmall fluorescent organic molecules, nanoparticles, andfluorescent proteins, e.g., GFP. It focuses on their preparations, photophysical properties, and advantages/disadvantagesfor intracellular pH measurements. The discussion is limitedto fluorescent indicators that have been applied to measureintracellular pH values since 1980. ... More
Time-domain fluorescence lifetime imaging for intracellular pH sensing in living tissues.
AuthorsHille C, Berg M, Bressel L, Munzke D, Primus P, Löhmannsröben HG, Dosche C,
JournalAnal Bioanal Chem
PubMed ID18481048
pH sensing in living cells represents one of the most prominent topics in biochemistry and physiology. In this study we performed one-photon and two-photon time-domain fluorescence lifetime imaging with a laser-scanning microscope using the time-correlated single-photon counting technique for imaging intracellular pH levels. The suitability of different commercial fluorescence dyes ... More
Monitoring autophagy in lysosomal storage disorders.
AuthorsRaben N, Shea L, Hill V, Plotz P,
JournalMethods Enzymol
PubMed ID19216919
Lysosomes are the final destination of the autophagic pathway. It is in the acidic milieu of the lysosomes that autophagic cargo is metabolized and recycled. One would expect that diseases with primary lysosomal defects would be among the first systems in which autophagy would be studied. In reality, this is ... More
The activation of P2X7 receptor impairs lysosomal functions and stimulates the release of autophagolysosomes in microglial cells.
AuthorsTakenouchi T, Nakai M, Iwamaru Y, Sugama S, Tsukimoto M, Fujita M, Wei J, Sekigawa A, Sato M, Kojima S, Kitani H, Hashimoto M,
JournalJ Immunol
PubMed ID19201858
Recently, autophagy has been associated with the TLR signaling pathway to eliminate intracellular pathogens in the innate immune system. However, it is unknown if other pathways regulate autophagy during the immunologic response. Given the critical role of the purinergic P2X7 receptor (P2X7R) pathway during various immunologic functions (i.e., caspase activation ... More
Protective role of endogenous gangliosides for lysosomal pathology in a cellular model of synucleinopathies.
AuthorsWei J, Fujita M, Nakai M, Waragai M, Sekigawa A, Sugama S, Takenouchi T, Masliah E, Hashimoto M,
JournalAm J Pathol
PubMed ID19349362
Gangliosides may be involved in the pathogenesis of Parkinson's disease and related disorders, although the precise mechanisms governing this involvement remain unknown. In this study, we determined whether changes in endogenous ganglioside levels affect lysosomal pathology in a cellular model of synucleinopathy. For this purpose, dementia with Lewy body-linked P123H ... More
Fluorescent imaging of Cl- in Amphiuma red blood cells: how the nuclear exclusion of Cl- affects the plasma membrane potential.
AuthorsHoffman JF, Geibel JP
JournalProc Natl Acad Sci U S A
PubMed ID15637151
In this work, we test the idea that most, if not all, cellular Cl- of Amphiuma red blood cells is contained in the cytoplasm. If true, this could resolve the difference between the measured plasma membrane potential (Em) and that expected from the Donnan equilibrium distribution of Cl-. We studied ... More