Penetration of semliki forest virus from acidic prelysosomal vacuoles

Marsh, Mark; Bolzau, E; Helenius, Ari

doi:10.1016/0092-8674(83)90078-8

Cited by 392 publications

(297 citation statements)

References 32 publications

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“…Penetration of Semliki Forest virus requires exposure to a pH of 6.2 or below and occurs after a lag of a few minutes after internalization in various cell types (12,16). This is consistent with penetration occurring from large endosomes.…”

Section: Discussionsupporting

confidence: 54%

Acidification of morphologically distinct endosomes in mutant and wild-type Chinese hamster ovary cells.

Yamashiro

Maxfield

1987

The Journal of Cell Biology

114

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we have shown that there is rapid acidification of endosomal compartments to pH 6.3 by 3 min in wildtype Chinese hamster ovary (CHO) cells. In contrast, early acidification of endosomes is markedly reduced in the CHO mutants, DTF 1-5-4 and DTF 1-5-1. Since these CHO mutants are pleiotropically defective in endocytosis (Robbins, A. R., S. S. Peng, and J. L. Marshall. 1983. J. Cell Biol. 96:1064-1071; Robbins, A. R., C. Oliver, J. L. Bateman, S. S. Krag, C. J. Galloway, and I. Mellman. 1984. J. Cell Biol. 99" 1296-1308, our results are consistent with a requirement for proper acidification of early endocytic compartments in many pH-regulated endocytic processes. In this paper, by measuring the pH of morphologically distinct endosomes using fluorescence microscopy and digital image analysis, we have determined in which of the endocytic compartments the defective acidification occurs. We found that the acidification of both the para-Golgi recycling endosomes and lysosomes was normal in the CHO mutants DTG 1-5-4 and DTF 1-5-1. The mean pH of large endosomes containing either fluorescein-labeled r or fluorescein-isothiocyanate dextran was only slightly less acidic in the mutant cells than in wild-type cells. However, when we examined the pH of individual large (150-250 nm) endosomes, we found that there was an increased number of endosomes with a pH >6.5 in the CHO mutants when compared with wildtype cells. Heterogeneity in the acidification of large endosomes was also seen in DTF 1-5-1 by a combined null point pH method and digital image analysis technique. In addition, both CHO mutants showed a marked decrease in the acidification of the earliest endosomal compartment, a diffusely fluorescent compartment comprised of small vesicles and tubules. We suggest that the defect in endosome acidification is most pronounced in the early, small vesicular, and tubular endosomes and that this defect partially carries over to the large endosomes that are involved in the sorting and processing of ligands. The proper step-wise acidification of the different endosomes along the endocytic pathway may have an important role in the regulation of endocytic processes.I N the preceding paper (40) we examined the kinetics of endosome acidification in wild-type and mutant Chinese hamster ovary (CHO) cells. We found in wild-type cells that there was a rapid (3-5 min) acidification of endosomes to pH 6.2-6.3. With time, ct~-macroglobulin (a2M) ~ and fluorescein-isothiocyanate dextran (F-Dex), molecules that are routed to lysosomes, are found in progressively more acidic endocytic compartments (pH < 6.0), while transferrin Dr. Maxfieid's present address is Departments of Pathology and Physiology, College of Physicians and Surgeons, Columbia University, New York, NY 10032.1. Abbreviations used in this paper: a2M, u2-macroglobulin; a2M-gold, a2-macroglobulin adsorbed to colloidal gold; AA/MA, ammonium acetate/methylamine; F-a2M, fluorescein-labeled ct2-macroglobulin; F-Dex, fluorescein isothioeyanate dextran; F-Tf, fluorescein-labeled transferr...

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Section: Discussionsupporting

confidence: 54%

Acidification of morphologically distinct endosomes in mutant and wild-type Chinese hamster ovary cells.

Yamashiro

Maxfield

1987

The Journal of Cell Biology

114

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“…It is known that VSV is endocytosed to early endosomes, where low pH triggers endosomal fusion. 33 Using the same fluorescence dequenching assay, we observed the viral fusion of FUWGFPVpr/VSVG. The acquired images showed that virus-endosome fusion could be detected at 10 min after incubation (Figure 2c, lower), indicating that viral fusion of VSVG-pseudotyped lentivirus occurs faster than that of the engineered targeting lentivirus.…”

Section: Intracellular Trafficking Of the Engineered Lentivirusmentioning

confidence: 99%

Visualization of targeted transduction by engineered lentiviral vectors

Joo

Wang

2008

Gene Ther

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“…One of the major events in the life cycle of Semliki Forest virus (SFV), the entry of the host cell, is known to be mediated by the viral spikes [1][2][3]. The composition of these spikes was determined to be a trimer of spike proteins, which in turn consist of two transmembrane glycoproteins, Em (MW 51,000) and E2 (MW 52,000), and a peripheral glycoprotein E 3 (MW 11,000) being attached to E2 [4].…”

Section: Introductionmentioning

confidence: 99%

Identification of the pore forming element of Semliki Forest virus spikes

1995

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Pore formation at mildly acidic pH by SFV spike proteins was investigated using isolated and modified virions. Modification of the virious was performed by limited proteolysis in presence of octylglucosidc and resulted in the formation of E1 particles and spikeless particles, respectively. Pore formation was detected by measuring the influx of propidium iodide into the viral particles. The results obtained clearly showed that the presence of El alone is sufficient to promote pore formation at mildly acidic pH. Thus E1 represents the pore forming element of the viral spike proteins.

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Penetration of semliki forest virus from acidic prelysosomal vacuoles

Cited by 392 publications

References 32 publications

Acidification of morphologically distinct endosomes in mutant and wild-type Chinese hamster ovary cells.

Acidification of morphologically distinct endosomes in mutant and wild-type Chinese hamster ovary cells.

Visualization of targeted transduction by engineered lentiviral vectors

Identification of the pore forming element of Semliki Forest virus spikes

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