Banca de DEFESA: AMANDA COUTO TAMBELLINI

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : AMANDA COUTO TAMBELLINI
DATE: 06/03/2026
TIME: 14:00
LOCAL: Auditório da Pós Graduação da Faculdade de Medicina
TITLE:

MODULATION OF THE OTULI GENE AND ITS INFLUENCE ON THE PROTEOMIC PLASTICITY OF Leishmania infantum: COMPARISON BETWEEN DELETION, OVEREXPRESSION, AND WILD-TYPE LINEAGE.

KEY WORDS:

Leishmania infantum; quantitative proteomics; OtuLi deubiquitinase; mutants; qualitative proteomics; ubiquitination; deubiquitination; leishmaniasis.

PAGES: 107
BIG AREA: Ciências Biológicas
AREA: Bioquímica
SUMMARY:

Visceral leishmaniasis (VL) is a neglected systemic disease that is potentially lethal when left untreated, caused by protozoa of the genus Leishmania, mainly Leishmania donovani and Leishmania infantum. Because it is an obligate intracellular parasite, the host's immune response mainly involves macrophages and neutrophils, and is associated with manifestations such as hepatosplenomegaly. Given the current therapeutic limitations — high toxicity, high cost, and the emergence of resistance — the identification of new molecular targets is essential. In this context, the ubiquitin-proteasome pathway stands out as a central mechanism of post-translational regulation, with the deubiquitinase OtuLi being responsible for the cleavage of ubiquitin chains linked to lysine 48 (K48), associated with proteasomal degradation.

In this study, a comparative qualitative and quantitative proteomic analysis was performed
to investigate the functional impact of OtuLi in L. infantum, using three
strains: the wild-type strain (WT), OtuLi overexpression
(FLAG-OtuLi), and gene deletion (DKO5), all evaluated in biological triplicate.

The samples were subjected to protein extraction, precipitation, reduction and
alkylation, digestion with trypsin and Lys-C, desalting at C18, and analysis by
LC-MS/MS. Protein identification was performed in PEAKS/Progenesis,
with redundancy filtering, followed by functional annotation in TriTrypDB and
statistical analysis in RStudio. Principal component analysis showed
high reproducibility and clear separation between the strains. Differential abundance analysis (p < 0.05; |log2FC| ≥ 1) identified 287 regulated proteins. Integrated approaches using heatmaps, volcano plots, and protein-protein interaction networks demonstrated coordinated modulation of functional modules, with emphasis on proteins of the translational machinery. The DKO5 strain showed a coordinated increase in ribosomal proteins and translation factors, suggesting reorganization of the translational axis in the absence of OtuLi, while FLAG-OtuLi showed enrichment of proteins associated with energy metabolism and catalytic processes. Candidate proteins for possible direct substrates of OtuLi were also identified, including uncharacterized proteins and proteins with Alba-like domains, related to post-transcriptional regulation. Taken together, the results indicate that OtuLi plays a central role in the functional organization of the L. infantum proteome, impacting the translation, proteostasis, and metabolism axes, reinforcing its relevance as a post-translational regulator and potential molecular target.

 

COMMITTEE MEMBERS:
Presidente - 2492352 - IZABELA MARQUES DOURADO BASTOS CHARNEAU
Externo à Instituição - Kaio Luís da Silva Bentes - UCB
Externa à Instituição - MILENE APARECIDA ANDRADE - MS
Interno - 1254630 - WAGNER FONTES