Use of RIP1 Kinase Small-Molecule Inhibitors in Studying Necroptosis.

RIP1 kinase plays a key role in regulating signaling pathways downstream of a number of innate immune receptors such as TNFRI and TLRs. The discovery of Necrostatin-1 (Nec-1) as a small-molecule inhibitor of RIP1 kinase has been very instrumental in defining the necroptotic and other signalling pathways regulated by RIP1, but certain characteristics of Nec-1 limits its utility in experimental systems. Next generation RIP1 kinase inhibitors have been identified and the use of these tool inhibitors along with Nec-1 has revealed that RIP1 is emerging as a key driver of inflammation and tissue injury in the pathogenesis of various diseases. Further studying the role of RIP1 to carefully unravel the complex biology requires the selection of the correct tool small-molecule inhibitors. In addition, it is important to consider the proper application of current tool inhibitors and understand the current limitiations. Here we will discuss key parameters that need to be considered when selecting and applying tool inhibitors to novel biological assays and systems. General protocols to explore the in vitro and in vivo potency, cellular selectivity, and pharmacokinetic properties of current small-molecule inhibitors of RIP1 kinase are provided.