Jeffrey K. Kerns

Keap Calm, and Carry on Covalently

The Nrf2-Keap1 system plays a major role in cellular defense against oxidative stress. Upon exposure to electrophiles, the cysteine-rich protein Keap1 is covalently modified, and it is this modification of Keap1 that allows the accumulation and subsequent nuclear translocation of Nrf2 where it induces the transcription of over 100 protective genes. This mechanism can be exploited in drug discovery approaches to diseases such as chronic kidney disease (CKD), chronic obstructive pulmonary disease (COPD), asthma, and neurodegenerative diseases like multiple sclerosis (MS) and Parkinsons, utilizing the modification of Keap1 by electrophiles, compounds that would not normally be considered useful in drug discovery programs. This Perspective discusses the development of potential therapies based on potent electrophiles, such as isothiocyanates and Michael acceptors, that, far from being associated with toxic events, can actually initiate a range of beneficial protective pathways.

Structure of the BTB Domain of Keap1 and Its Interaction with the Triterpenoid Antagonist CDDO

The protein Keap1 is central to the regulation of the Nrf2-mediated cytoprotective response, and is increasingly recognized as an important target for therapeutic intervention in a range of diseases involving excessive oxidative stress and inflammation. The BTB domain of Keap1 plays key roles in sensing environmental electrophiles and in mediating interactions with the Cul3/Rbx1 E3 ubiquitin ligase system, and is believed to be the target for several small molecule covalent activators of the Nrf2 pathway. However, despite structural information being available for several BTB domains from related proteins, there have been no reported crystal structures of Keap1 BTB, and this has precluded a detailed understanding of its mechanism of action and interaction with antagonists. We report here the first structure of the BTB domain of Keap1, which is thought to contain the key cysteine residue responsible for interaction with electrophiles, as well as structures of the covalent complex with the antagonist CDDO/bardoxolone, and of the constitutively inactive C151W BTB mutant. In addition to providing the first structural confirmation of antagonist binding to Keap1 BTB, we also present biochemical evidence that adduction of Cys 151 by CDDO is capable of inhibiting the binding of Cul3 to Keap1, and discuss how this class of compound might exert Nrf2 activation through disruption of the BTB-Cul3 interface.

Discovery of 6-Aryl-7-alkoxyisoquinoline Inhibitors of IκB Kinase-β (IKK-β)

The identification and progression of a potent and selective series of isoquinoline inhibitors of IkappaB kinase-beta (IKK-beta) are described. Hit-generation chemistry based on IKK-beta active-site knowledge yielded a weakly potent but tractable chemotype that was rapidly progressed into a series with robust enzyme and cellular activity and significant selectivity over IKK-alpha.

Progress Towards the Development of Anti-Inflammatory Inhibitors of IKKβ

The IkappaB kinases (IKKs) are essential components of the signaling pathway by which the NF-kappaB p50/RelA transcription factor is activated in response to pro-inflammatory stimuli such as lipopolysaccharide (LPS) and tumor necrosis factor (TNFalpha). NF-kappaB signaling results in the expression of numerous genes involved in innate and adaptive immune responses. The pathway is also implicated in chronic inflammatory disorders including rheumatoid arthritis (RA), chronic obstructive pulmonary disorder (COPD), and asthma. Inhibition of the kinase activity of the IKKs is therefore a promising mechanism for intervention in these diseases. Here, we will review the literature describing small molecule inhibitors of IKKbeta (IKK2), the most widely studied of the IKKs.

3,5-Disubstituted-indole-7-carboxamides: The discovery of a novel series of potent, selective inhibitors of IKK-β

The discovery and hit-to-lead exploration of a novel series of selective IKK-β kinase inhibitors is described. The initial lead fragment 3 was identified by pharmacophore-directed virtual screening. Homology model-driven SAR exploration of the template led to potent inhibitors, such as 12, which demonstrate efficacy in cellular assays and possess encouraging developability profiles.

A Highly Convergent Synthesis of 2‐Phenyl Quinoline as Dual Antagonists for NK2 and NK3 Receptors

Abstract A novel and highly convergent synthesis leading to 2‐phenyl‐quinolines has been developed. As demonstrated in the preparation of 6‐fluoro‐3‐(3‐oxo‐piperazin‐1‐ylmethyl)‐2‐phenyl‐quinoline‐4‐carboxylic acid [(S)‐1‐cyclohexyl‐ethyl]‐amide (8), the method provides fascile access to this class of analogues via the common intermediate 7.

Characterization of the Potent, Selective Nrf2 Activator, 3-(Pyridin-3-Ylsulfonyl)-5-(Trifluoromethyl)-2H-Chromen-2-One, in Cellular and In Vivo Models of Pulmonary Oxidative Stress

Nuclear factor (erythroid-derived 2)–like 2 (Nrf2) is a key regulator of oxidative stress and cellular repair and can be activated through inhibition of its cytoplasmic repressor, Kelch-like ECH-associated protein 1 (Keap1). Several small molecule disrupters of the Nrf2-Keap1 complex have recently been tested and/or approved for human therapeutic use but lack either potency or selectivity. The main goal of our work was to develop a potent, selective activator of NRF2 as protection against oxidative stress. In human bronchial epithelial cells, our Nrf2 activator, 3-(pyridin-3-ylsulfonyl)-5-(trifluoromethyl)-2H-chromen-2-one (PSTC), induced Nrf2 nuclear translocation, Nrf2-regulated gene expression, and downstream signaling events, including induction of NAD(P)H:quinone oxidoreductase 1 (NQO1) enzyme activity and heme oxygenase-1 protein expression, in an Nrf2-dependent manner. As a marker of subsequent functional activity, PSTC restored oxidant (tert-butyl hydroperoxide)–induced glutathione depletion. The compound’s engagement of the Nrf2 signaling pathway translated to an in vivo setting, with induction of Nrf2-regulated gene expression and NQO1 enzyme activity, as well as restoration of oxidant (ozone)–induced glutathione depletion, occurring in the lungs of PSTC-treated rodents. Under disease conditions, PSTC engaged its target, inducing the expression of Nrf2-regulated genes in human bronchial epithelial cells derived from patients with chronic obstructive pulmonary disease, as well as in the lungs of cigarette smoke–exposed mice. Subsequent to the latter, a dose-dependent inhibition of cigarette smoke–induced pulmonary inflammation was observed. Finally, in contrast with bardoxolone methyl and sulforaphane, PSTC did not inhibit interleukin-1β–induced nuclear factor-κB translocation or insulin-induced S6 phosphorylation in human cells, emphasizing the on-target activity of this compound. In summary, we characterize a potent, selective Nrf2 activator that offers protection against pulmonary oxidative stress in several cellular and in vivo models.Word Count: 250 Introduction Word Count: 690 Discussion Word Count: 886 This article has not been copyedited and formatted. The final version may differ from this version. JPET Fast Forward. Published on August 8, 2017 as DOI: 10.1124/jpet.117.241794 at A PE T Jornals on A uust 0, 2017 jpet.asjournals.org D ow nladed from