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Scientific article
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English

Localization of intracellular Ca2+ stores in HeLa cells during infection with Chlamydia trachomatis

Published inJournal of cell science, vol. 112, no. 1, p. 35-44
Publication date1999
Abstract

Chlamydia trachomatis elementary bodies (EBs) enter epithelial cells within membrane-bound endosomes that aggregate with each other in a calcium-regulated process, but avoid fusion with lysosomes. Annexin III but not I translocates to chlamydial aggregates and inclusions. In this study, we localize the intracellular Ca2+ stores during the course of infection by analyzing the distribution of three intracellular Ca2+ store proteins: calreticulin, type-1 inositol-1,4, 5-trisphosphate receptor (IP3-R), and Sarcoplasmic/Endoplasmic Reticulum Ca2+ ATPase type 2 (SERCA2) in HeLa cells infected with C. trachomatis serovar L2. In uninfected cells, immunofluorescence staining of the proteins showed a fine granular distributed pattern for all three proteins. After infection with C. trachomatis, calreticulin was found at the periphery of chlamydial aggregates and inclusions from 3 to 48 hours post-infection. In infected cells, SERCA2 was intimately associated with chlamydial inclusions after 3 and 24 hours, but not after 48 hours. Moreover, IP3-R was translocated to and colocalized with EB aggregates and chlamydial inclusions and had a distribution very similar to that of SERCA 2. After 24 hours incubation with chlamydiae, there was a local accumulation of [Ca2+]i (105+/-17 nM) in the proximity of chlamydial inclusions, compared to 50+/-13 nM in other parts of the cell cytoplasm. In the absence of extracellular Ca2+, this local accumulation of Ca2+ increased to 295+/-50 nM after adding 50 microM ATP, and to a similar extent after adding 100 nM thapsigargin (Tg). These data indicate that during infection of HeLa cells with chlamydiae, intracellular Ca2+ stores are redistributed, causing local accumulation of Ca2+ in the vicinity of chlamydial inclusions. These changes may trigger the association of certain proteins such as annexins with chlamydia-containing vesicles, and thereby regulation of membrane-membrane interaction during endosome aggregation and inclusion formation.

Keywords
  • Adenosine Triphosphate/pharmacology
  • Antibody Specificity
  • Calcium/ metabolism
  • Calcium Channels/immunology/metabolism
  • Calcium-Binding Proteins/immunology/metabolism
  • Calcium-Transporting ATPases/antagonists & inhibitors/immunology/metabolism
  • Calreticulin
  • Chlamydia Infections/ metabolism/microbiology
  • Chlamydia trachomatis/metabolism/pathogenicity
  • Chloramphenicol/pharmacology
  • Emetine/pharmacology
  • Endocytosis/physiology
  • Fluorescent Antibody Technique
  • Hela Cells
  • Humans
  • Inositol 1,4,5-Trisphosphate Receptors
  • Intracellular Fluid/ metabolism
  • Molecular Chaperones/immunology/metabolism
  • Receptors, Cytoplasmic and Nuclear/immunology/metabolism
  • Ribonucleoproteins/immunology/metabolism
  • Sarcoplasmic Reticulum/enzymology
  • Thapsigargin/pharmacology
  • Time Factors
Affiliation Not a UNIGE publication
Citation (ISO format)
MAJEED, M. et al. Localization of intracellular Ca2+ stores in HeLa cells during infection with Chlamydia trachomatis. In: Journal of cell science, 1999, vol. 112, n° 1, p. 35–44.
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Identifiers
ISSN of the journal0021-9533
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