Four young RIDC Redoxoma researchers have won the Travel Award from the Society for Redox Biology and Medicine (SfRBM) this year. Postdoctoral fellows Litiele Cruz and Felipe Fuzita and doctoral students Alex Inague and Rogério Aleixo Silva will present their research at the 29th SfRBM Annual Conference, which will be held November 16-19 in Orlando, United States.

Litiele Cruz, from Professor Flavia Meotti’s group, at the Instituto de Química at USP (IQ-USP), will present the work “Laminin is the main brominated protein by hypobromous acid and Peroxidasin in the extracellular matrix”.

She explains that peroxidasin is an extracellular matrix heme peroxidase that produces hypobromous acid (HOBr) from hydrogen peroxide and bromide. This HOBr in turn will crosslink the IV collagen in the basement membrane. What was not known until then is whether other extracellular matrix proteins, in addition to collagen IV, could be targets of the HOBr produced from peroxidasin.

“In this work, we identified these proteins by evaluating the formation of modifications (bromotyrosines and/or dibromotyrosines) of tyrosine residues in the extracellular matrix. Laminin was the protein with the highest number of brominated tyrosines. We still don’t know the consequences or even the function of these changes in laminin. However, our work provides unprecedented information on HOBr/peroxidasin target proteins and may be the first to show peroxidasin oxidative mechanisms unrelated to collagen IV crosslink in the extracellular matrix.”

Felipe Fuzita, from Professor Paolo Di Mascio’s group at IQ-USP, received the SfRBM Journal Travel Award, and in addition to the presentation at the congress, he must submit an article related to his work to one of SfRBM’s journals within one year. He will present the work “A simple and direct approach for cysteine-based redox proteomics by differential isobaric labeling validated in human and rat aortic smooth muscle cells.”

The researcher highlights that “among the approaches used in redox proteomics, the differential labeling of cysteine ​​residues allows the identification and quantification of their oxidation state under different conditions. We have developed a protocol for isobaric labeling and quantification of differentially oxidized peptides more efficient than those currently used, which does not require prior enrichment of the sample, reducing, in addition to processing time, possible biases that preparations with more steps can introduce. Finally, the method used was validated in rat and human aortic cells, in which we identified, respectively, 1,704 and 1,973 differentially oxidized peptides after treatment with hydrogen peroxide”.

Alex Inague, from Professor Sayuri Miyamoto’s group at IQ-USP, will present the work “7-Dehydrocholesterol protects membrane phospholipids from oxidation”, with part of the data generated in a project in collaboration with Professor José Pedro Friedmann Angeli, from the University of Würzburg, Germany.

“In this work, we identified and characterized the (unexpected) anti-ferroptotic activity of 7-dehydrocholesterol (7-DHC). Specifically, we show that the deletion of the DHCR7 enzyme - which converts 7-DHC to cholesterol - leads to the intracellular accumulation of 7-DHC and protection against ferroptosis, a form of cell death that depends on the oxidation of phospholipids. This activity against ferroptosis is unexpected because 7-DHC has previously been pointed out as an extremely oxidizable lipid, which would lead to oxidation - not protection - of biological membranes. We showed that, contrary to what was thought, 7-DHC acts as a ”classic“ antioxidant: during lipid peroxidation, it oxidizes in place of other molecules, protecting phospholipids and membrane integrity. The same action was observed for another sterol with a structure practically identical to that of 7-DHC - ergosterol, widely found in the cell membranes of fungi and some protozoa.”

According to Inague, the relevance of this research lies in understanding the mechanisms that determine cellular sensitivity to ferroptosis. These mechanisms can be explored in the development of therapies against some types of cancer resistant to other forms of cell death. “In the article, for example, we investigated mutations in the DHCR7 gene already described for Burkitt lymphomas, in which the accumulation of 7-DHC can suppress ferroptosis sensitivity and confer growth/proliferation advantages.”

Rogério Aleixo Silva, from the group led by Professor Luis Netto, at the Instituto de Biociências at USP, will present the work entitled “LsfA, a 1-Cys Peroxiredoxin involved with Pseudomonas aeruginosa virulence: Structure, biochemical activity, and its influence in inflammation/resolution”

“Our work aims to study a peroxiredoxin - an antioxidant enzyme - involved with the virulence of a super bacterium, Pseudomonas aeruginosa. To understand this process, we first studied with which molecules this protein would be able to react, and we verified that it can reduce a wide range of oxidants very efficiently. In addition, we saw that vitamin C can reduce this protein and make it able to reduce oxidants again. We also solved two crystallographic structures of this protein, which may enable future searches for inhibitors. Finally, we have identified in an unprecedented way that this bacterial antioxidant protein can alter the production of lipid mediators related to the inflammation process in our body’s defense cells (macrophages). And this can affect the course of inflammation and its resolution by altering the signaling process of these cells,” explains the researcher.