MICAL proteins are primary oxidases in receptor-induced redox signaling relays

• Applicant: Dr. Manuela Gellert
• Subject Area: Cell Biology ; Biochemistry
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 557899655

Redox signaling controls essentially all central signaling and metabolic pathways. Like phosphorylation signaling, redox signaling requires the controlled and specific posttranslational modification of critical protein side chains, here cysteinyl and methionyl residues. Proteins of the thioredoxin family, i.e., thioredoxins, glutaredoxins, and methionine sulfoxide reductases, are essential enzymes in reducing oxidized cysteinyl- and methionyl-derivates. An open question is how redox switches are oxidized. The specific modification of target proteins cannot be induced by the release of, e.g., H2O2. In our work that led to this proposal, we have characterized the monoxygenase MICAL1 as the specific initiator of a redox signaling relay induced by semaphorin receptors. The relay includes peroxiredoxin 1 as a transducer and CRMP2 as effector proteins. This pathway controls cytoskeletal dynamics and, thus, axonal outgrowth and neuronal development, and it contributes to the malignant transformation of cancer cells. Here, we propose that all three human MICAL oxidases are signal-regulated oxidases that initiate redox relay pathways by oxidizing peroxiredoxins and other transducer proteins. Preliminary mass spectrometry data with a silenced expression of MICAL 1 or Prx1 that show an increase in reduced proteins, e.g., cofilin 1, support this hypothesis. The primary focus of our work will be pathways that regulate cytoskeletal dynamics in models of neuronal differentiation and malignant transformation. The following objectives and aims are the basis of this proposal: First, to identify and confirm redox relays in our cell culture models. We will focus on identifying specific targets of MICAL1-3 as primary oxidases and Prx1-2 as transducer proteins. Second, to characterize the different domains of the three MICAL proteins. We propose that these function as specific protein-protein recognition platforms or even as scaffolds to bring downstream relay proteins into direct proximity. Third, to characterize newly identified transducer and target proteins in vitro and in vivo/cellulo. Based on established cell culture models for cellular differentiation, development, and transformation, we will utilize advanced redox proteomics strategies, state-of-the-art genetically encoded redox sensors, high-throughput analyses of the mechanical properties of cells, biochemical studies, and enzyme kinetics. This program will improve our understanding of specific oxidative protein modifications as part of redox signaling events essential for life. Disruption of redox signaling pathways is crucially involved in various diseases. This research project will characterize new redox relay cascades of physiological and pathological importance that may be suited as therapeutic targets to address pathologies such as neuronal degeneration and malignant transformation.

• DFG Programme: Research Grants