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| Author(s): |
Hadassa Cristhina de Azevedo Soares dos Santos
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2016-05-13 |
| Examining board members: |
Marina Baquerizo;
Sandro Rogerio de Almeida;
Tania Aparecida Tardelli Gomes do Amaral
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| Advisor: | Marina Baquerizo |
| Abstract | |
The invasive bacteria recognition by host cells through autophagy is a key factor for determining bacterial infection. Enteroinvasive Escherichia coli (EIEC) express a protein IcsB, which in Shigella, is known for inactivating the bacterial degradation process. Once EIEC showed less expression of icsB when compared to S. flexneri, we proposed to investigate the autophagy caused by EIEC infection, using techniques such as gene mutation by insertion, western blot, fluorescence microscopy, transmission electron microscopy and microarray. Our results showed that IcsB protein is an important virulence factor in EIEC because it causes a camouflage of the bacteria in the eukaryotic cell. When there is a low expression of the protein, the cell recognition of the invasive bacteria is high, decreasing the bacteria dissemination. This found confirms the importance of the gene transcription and the gene sequence, since the strain E. coli SM124/13, complemented with icsB from Shigella, showed higher dissemination efficiency inside of the host cell. Interestingly, IcsB showed a new role on regulating the inflammatory response in Hela cells. The absence of IcsB in EIEC generated an intense disturbance of the cell homeostasis, increased the secretion of IL-6 and IL-8, and caused cell death. Additionally, our results revealed that eukaryotic cell infected by EIEC or Shigella flexneri showed distinguish responses. In EIEC infection, the autophagy was activated in human cells, but not in a conventional mode. Our hypothesis is that EIEC is recognized by autophagy, being an important cell process for bacterial recognition. This process can cause a decrease in the intracellular spread of EIEC making the infection less severe when compared to the infection caused by Shigella. (AU) | |
| FAPESP's process: | 12/01123-6 - Autophagic process in recognition of Enteroinvasive Escherichia coli mediated by icsA and icsB: a possible mechanism of bacterial degradation by intestinal epithelial cells |
| Grantee: | Hadassa Cristhina de Azevedo Soares dos Santos |
| Support Opportunities: | Scholarships in Brazil - Doctorate |