Redox proteomics reveals an interdependence of redox modification and location of adhesome proteins in NGF-treated PC12 cells

Abstract

Proteomics studies have revealed that adhesomes are assembled from a plethora of proteins at integrin-mediated cellular contact sites with the extracellular matrix. By combining dimedone-trapping of sulfenylated proteins with the purification of the adhesome complex, we extended previous proteomics approaches on adhesomes to a redox proteomic analysis. This added a new aspect of adhesome complexity as individual adhesome proteins change their redox state in response to environmental signals. As model system, rat pheochromocytoma PC12 cells were studied in contact with type IV collagen and in response to nerve growth factor (NGF). NGF stimulates the endogenous production of reactive oxygen species (ROS) and the formation of neurite-like cell protrusions, which are anchored to the substratum via adhesomes. Dimedone detects the reversible oxidation of cysteine thiol groups into sulfenic acid groups which was used in proteomic analysis of adhesome proteins revealing that sulfenylation and location of proteins mutually influence each other. For some proteins, identified by the redox proteomics approach, among them Nck-associated protein-1 (Nap-1), proximity ligation analysis and co-immunoprecipitation assays proved that protein sulfenylation sites colocalize with adhesomes of protrusions. In conclusion, the suprastructural composition and function of adhesomes is redox-regulated by ROS. Of interest in this respect, isoform-selective pharmacological inhibition of NADPH-oxidases (Noxs) reduced the adhesomal location of the collagen-binding α1β1 integrin and the length of the outgrowing neurites, indicative of a role of Nox isoforms in the redox-regulation of adhesomes. Thus, our novel redox proteomics approach not only revealed redox-modifications and the potential redox-regulation of adhesomes and their constituents but it may also provide a tool to analyze the ROS-stimulated neurite repair of peripheral neurons.