Biochemical regulation and functional characterization of soluble ADAM10 and ADAM17

• Applicant: Dr. Franka Scharfenberg
• Subject Area: Biochemistry
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 469309156

The proteome regulates through its dynamic composition the physiological state of the cells and thus that of the entire organism. Proteases play a key role in this process. They degrade other proteins or specifically modify their function and subcellular localization by specific cleavage. A large number of known membrane proteins are cleaved at or within the cell membrane by a process known as shedding. Subsequently, their ectodomains are released into the extracellular space, making them e.g. systemically available as ligands for other surface receptors. It has been shown that shedding of growth factors, cytokines, surface receptors and cell adhesion molecules is of fundamental importance for a variety of signaling processes. Especially the ubiquitously expressed membrane-bound metalloproteases ADAM10 and ADAM17 of the ADAM family are described as prototypical sheddases. Due to the broad spectrum of specific and common substrates, these two proteases are considered to be important molecular switches. They are involved in a wide range of processes such as development, tissue regeneration, inflammation, cardiovascular diseases, cancer and neurodegenerative pathologies. The activity of the two proteases is regulated at various levels, which are currently only partially understood in their complexity. However, so far only weakly addressed is the proteolytic release of ADAM10 and ADAM17 themselves. Shedding of these two proteases has been described, but functional consequences have mainly been discussed with regard to impaired ectodomain shedding. Nonetheless, shedding of ADAM10 and ADAM17 might not be solely a mechanism to downregulate cell surface activity of these proteases, but rather enables a completely new substrate spectrum apart from the plasma membrane. The initial results on the function of soluble ADAM10/17 imply additional so far underestimated roles within the ‘protease web’ as soluble enzymes. However, underlying mechanisms regulating the shedding of these essential proteases are only poorly understood. This project aims to explore, how and when soluble ADAM10/17 contribute to physiological and/or pathophysiological conditions. To achieve this, a multidisciplinary approach of cell biological, biochemical and mass spectrometry methods will be used to investigate 1.) which mechanisms regulate the release of soluble ADAM10/17, 2.) how the substrate spectrum of soluble differs from membrane-bound ADAM10/17, 3.) whether indirect or non-proteolytic interactions of soluble ADAM10/17 affect the proteome and 4.) what are the functional consequences of increased soluble ADAM17 shedding in breast cancer cells.

• DFG Programme: Research Grants