Our research group primarily focuses on the mechanisms by which the ubiquitin-proteasome system (UPS) governs protein homeostasis (also referred to as “proteostasis”) under physiological and/or pathological conditions. Our main objective is to understand the processes of homeostasis perturbations at the crossroad between oxidative stress and the immune response. The UPS serves as the principal non-lysosomal mode of protein breakdown, thereby fining-tune the balance between protein synthesis, quality control and degradation and controlling the availability of a vast number of signal molecules regulating many cellular processes. Because such balance may be disturbed through oxidative stress, the UPS may be defined as a major component of the cellular anti-oxidative defense. Oxidative stress targets both cytosolic and secretory proteins, the latter being eliminated by the endoplasmic reticulum-associated degradation (ERAD) pathway. By the supply of MHC class I-restricted antigenic peptides from self and/or viral proteins recognized by CD8+ by cytotoxic T cells (CTL) the UPS is actively involved in the adaptive immune response. The UPS also plays a critical role during innate immunity by protecting cells and tissues against harmful reactions through the systematic elimination of damaged and/or oxidized proteins. Overall, our group pursues basic and translational research on topics related to medical biochemistry, biochemistry and pathobiochemistry with the aim of uncovering the pathogenesis of diseases associated with perturbed protein homeostasis such as auto-inflammatory diseases, cancer, infectious diseases and neurodegenerative diseases. Our work is supported by the German Research Foundation and the Fritz Thyssen Foundation.