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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

The intracellular bacterium Rickettsia rickettsii exerts an inhibitory effect on the apoptosis of tick cells

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Martins, Larissa Almeida [1, 2] ; Palmisano, Giuseppe [1] ; Cortez, Mauro [1] ; Kawahara, Rebeca [1, 3] ; de Freitas Balanco, Jose Mario [1] ; Fujita, Andre [4] ; Alonso, Beatriz Iglesias [1] ; Barros-Battesti, Darci Moraes [5] ; Braz, Gloria Regina Cardoso [6] ; Tirloni, Lucas [2] ; Esteves, Eliane [1] ; Daffre, Sirlei [1] ; Fogaca, Andrea Cristina [1]
Total Authors: 13
[1] Univ Sao Paulo, Inst Biomed Sci, Dept Parasitol, Sao Paulo, SP - Brazil
[2] NIAID, Rocky Mt Lab, NIH, Hamilton, MT 59840 - USA
[3] Macquarie Univ, Dept Mol Sci, Sydney, NSW - Australia
[4] Univ Sao Paulo, Inst Math & Stat, Dept Computat Sci, Sao Paulo, SP - Brazil
[5] Sao Paulo State Univ, Dept Vet Pathol, Jaboticabal, SP - Brazil
[6] Univ Fed Rio de Janeiro, Inst Chem, Dept Biochem, Rio De Janeiro, RJ - Brazil
Total Affiliations: 6
Document type: Journal article
Source: PARASITES & VECTORS; v. 13, n. 1 DEC 1 2020.
Web of Science Citations: 0

Background Rickettsia rickettsii is a tick-borne obligate intracellular bacterium that causes Rocky Mountain spotted fever, a life-threatening illness. To obtain an insight into the vector-pathogen interactions, we assessed the effects of infection with R. rickettsii on the proteome cells of the tick embryonic cell line BME26. Methods The proteome of BME26 cells was determined by label-free high-performance liquid chromatography coupled with tandem mass spectrometry analysis. Also evaluated were the effects of infection on the activity of caspase-3, assessed by the hydrolysis of a synthetic fluorogenic substrate in enzymatic assays, and on the exposition of phosphatidyserine, evaluated by live-cell fluorescence microscopy after labeling with annexin-V. Finally, the effects of activation or inhibition of caspase-3 activity on the growth of R. rickettsii in BME26 cells was determined. Results Tick proteins of different functional classes were modulated in a time-dependent manner by R. rickettsii infection. Regarding proteins involved in apoptosis, certain negative regulators were downregulated at the initial phase of the infection (6 h) but upregulated in the middle of the exponential phase of the bacterial growth (48 h). Microorganisms are known to be able to inhibit apoptosis of the host cell to ensure their survival and proliferation. We therefore evaluated the effects of infection on classic features of apoptotic cells and observed DNA fragmentation exclusively in noninfected cells. Moreover, both caspase-3 activity and phosphatidylserine exposition were lower in infected than in noninfected cells. Importantly, while the activation of caspase-3 exerted a detrimental effect on rickettsial proliferation, its inhibition increased bacterial growth. Conclusions Taken together, these results show that R. rickettsii modulates the proteome and exerts an inhibitory effect on apoptosis in tick cellsthat seems to be important to ensure cell colonization. (AU)

FAPESP's process: 12/24105-3 - Immunobiology of Leishmania spp: study of the role of CD200 and biogenesis of parasitophorous vacuole in fagocitic cells infected by Leishmania
Grantee:Mauro Javier Cortez Véliz
Support type: Research Grants - Young Investigators Grants
FAPESP's process: 18/15549-1 - Post-translational modifications in Chagas Disease biological processes and diagnostics: novel methodological approaches and biological applications
Grantee:Giuseppe Palmisano
Support type: Research Grants - Young Investigators Grants - Phase 2
FAPESP's process: 18/18257-1 - Multi-user equipment approved in grant 14/06863-3: HPLC system configured for analysis of carbohydrates, amino acidis, peptides and glycoproteins
Grantee:Giuseppe Palmisano
Support type: Multi-user Equipment Program
FAPESP's process: 14/11513-1 - Determination of the differential proteome and lipidome of Amblyomma aureolatum ticks in response to Rickettsia rickettsii infection
Grantee:Andréa Cristina Fogaça
Support type: Regular Research Grants
FAPESP's process: 14/06863-3 - Post-translational modifications in cancer and parasite infection diagnosis: methodological approaches and biological implications
Grantee:Giuseppe Palmisano
Support type: Research Grants - Young Investigators Grants
FAPESP's process: 14/05855-7 - Determination of the proteome of Rickettsia rickettsii, the etiological agent of Brazilian Spotted Fever
Grantee:Larissa Almeida Martins
Support type: Scholarships in Brazil - Doctorate
FAPESP's process: 13/26450-2 - Molecular characterization of the interactions among ticks, rickettsiae and vertebrate hosts
Grantee:Sirlei Daffre
Support type: Research Projects - Thematic Grants