The Prohibitin-Binding Compound Fluorizoline Activates the Integrated Stress Response through the eIF2α Kinase HRI.

Fluorizoline is a synthetic molecule that induces apoptosis, by selectively targeting prohibitins (PHBs), through induction of the BH3-only protein NOXA. This induction is transcriptionally regulated by the integrated stress response (ISR)-related transcription factors ATF3 and ATF4. Here, we evaluate the role of the four eIF2α kinases, to decipher which is responsible for the mechanism of ISR activation triggered by fluorizoline in HeLa and HAP1 cells. First, we demonstrated the involvement of the eIF2α kinases using ISR inhibitor (ISRIB) and by simultaneous downregulation of all four eIF2α kinases, as both approaches were able to increase cell resistance to fluorizoline-induced apoptosis. Furthermore, we confirmed that fluorizoline treatment results in endoplasmic reticulum (ER) stress, as evidenced by PERK activation. Despite PERK activation, this kinase was not directly involved in the ISR activation by fluorizoline. In this regard, we found that the eIF2α kinases are capable of compensating for each other's loss of function. Importantly, we demonstrated that the mitochondrial-stress-related eIF2α kinase HRI mediates ISR activation after fluorizoline treatment.

Charting the Chemical Reaction Space around a Multicomponent Combination: Controlled Access to a Diverse Set of Biologically Relevant Scaffolds.

Charting the chemical reaction space around the combination of carbonyls, amines, and isocyanoacetates allows the description of new multicomponent processes leading to a variety of unsaturated imidazolone scaffolds. The resulting compounds display the chromophore of the green fluorescent protein and the core of the natural product coelenterazine. Despite the competitive nature of the pathways involved, general protocols provide selective access to the desired chemotypes. Moreover, we describe unprecedented reactivity at the C-2 position of the imidazolone core to directly afford C, S, and N-derivatives featuring natural products (e.g. leucettamines), potent kinase inhibitors, and fluorescent probes with suitable optical and biological profiles.

Charting the Chemical Reaction Space around a Multicomponent Combination: Controlled Access to a Diverse Set of Biologically Relevant Scaffolds.

Charting the chemical reaction space around the combination of carbonyls, amines, and isocyanoacetates allows the description of new multicomponent processes leading to a variety of unsaturated imidazolone scaffolds. The resulting compounds display the chromophore of the green fluorescent protein and the core of the natural product coelenterazine. Despite the competitive nature of the pathways involved, general protocols provide selective access to the desired chemotypes. Moreover, we describe unprecedented reactivity at the C-2 position of the imidazolone core to directly afford C, S, and N-derivatives featuring natural products (e.g. leucettamines), potent kinase inhibitors, and fluorescent probes with suitable optical and biological profiles.

Heterocycle-Based Multicomponent Reactions in Drug Discovery: From Hit Finding to Rational Design.

In the context of the structural complexity necessary for a molecule to selectively display a therapeutical action and the requirements for suitable pharmacokinetics, a robust synthetic approach is essential. Typically, thousands of relatively similar compounds should be prepared along the drug discovery process. In this respect, heterocycle-based multicomponent reactions offer advantages over traditional stepwise sequences in terms of synthetic economy, as well as the fast access to chemsets to study the structure activity relationships, the fine tuning of properties, and the preparation of larger amounts for preclinical phases. In this account, we briefly summarize the scientific methodology backing the research line followed by the group. We comment on the main results, clustered according to the targets and, finally, in the conclusion section, we offer a general appraisal of the situation and some perspectives regarding future directions in academic and private research.