Published: May 26, 2011 r2011 American Chemical Society 4172 dx.doi.org/10.1021/jm200274d | J. Med. Chem. 2011, 54, 4172–4186 ARTICLE pubs.acs.org/jmc Leucettines, a Class of Potent Inhibitors of cdc2-Like Kinases and Dual Specificity, Tyrosine Phosphorylation Regulated Kinases Derived from the Marine Sponge Leucettamine B: Modulation of Alternative Pre-RNA Splicing Mansour Debdab, † Franc - ois Carreaux,* ,† Steven Renault, † Meera Soundararajan, ‡ Oleg Fedorov, ‡ Panagis Filippakopoulos, ‡ Olivier Lozach, § Lucie Babault, § Tania Tahtouh, § Blandine Baratte, § Yasushi Ogawa, || Masatoshi Hagiwara, ^ Andreas Eisenreich, # Ursula Rauch, # Stefan Knapp, ‡ Laurent Meijer,* ,§ and Jean-Pierre Bazureau* ,† † Universit  e de Rennes 1, Sciences Chimiques de Rennes, UMR CNRS 6226, Groupe ‘Ing enierie Chimique & Mol  ecules pour le Vivant’ (ICMV), B^ at. 10A, Campus de Beaulieu, Avenue du G en eral Leclerc, CS 74205, 35042 Rennes cedex, France ‡ Nuffield Department of Clinical Medicine, Structural Genomics Consortium, Oxford University, Old Road Campus Research Building, Headington, Oxford OX3 7DQ, U.K. § Station Biologique de Roscoff, CNRS, ‘Protein Phosphorylation and Human Disease’ Group, Place G. Teissier, BP 74, 29682 Roscoff, France ) Department of Dermatology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan ^ Department of Anatomy and Developmental Biology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan # Charit  e-Universit € atsmedizin-Berlin, Campus B. Franklin, Centrum f€ ur Herz- und Kreislaufmedizin, Hindenburgdamm 30, 12203 Berlin, Germany b S Supporting Information ’ INTRODUCTION Marine organisms constitute a rich source of high diversity chemical structures. 1 Marine natural products are being explored for multiple biomedical applications, mostly as potential anticancer agents but also in other therapeutic indications such as inflamma- tion, neurodegenerative diseases, parasites, viral infections, and renal pathologies. 2 Among the many marine natural products that have been isolated, a number of molecules share a 2-aminoimida- zolone ring structure (Figure 1). The best studied molecules of this series include leucettamine B, 3,4 polyandrocarpamines, 5 dispacamide, 6 aplysinopsine, 7 and hymenialdisine. 8 The marine sponge alkaloid (Z)-hymenialdisine was found to be a nanomolar inhibitor of various protein kinases including glycogen synthase- 3β (GSK-3 β), casein kinase 1 (CK1), and different cyclin- dependent kinases (CDKs), 9 mitogen-activated protein kinase 1 (MEK-1), 10 and checkpoint kinase 1. 11 Protein kinases are the enzymes which catalyze protein phosphorylation, a key cellular regulatory mechanism which is frequently deregulated in human diseases. Consequently, protein kinases represent interesting Received: March 9, 2011 ABSTRACT: We here report on the synthesis, optimization, and biological characterization of leucettines, a family of kinase inhibitors derived from the marine sponge leucettamine B. Stepwise synthesis of analogues starting from the natural structure, guided by activity testing on eight purified kinases, led to highly potent inhibitors of CLKs and DYRKs, two families of kinases involved in alternative pre-mRNA splicing and Alzhei- mer’s disease/Down syndrome. Leucettine L41 was cocrystal- lized with CLK3. It interacts with key residues located within the ATP-binding pocket of the kinase. Leucettine L41 inhibits the phosphorylation of serine/arginine-rich proteins (SRp), a family of proteins regulating pre-RNA splicing. Indeed leucettine L41 was demonstrated to modulate alternative pre-mRNA splicing, in a cell-based reporting system. Leucettines should be further explored as pharmacological tools to study and modulate pre-RNA splicing. Leucettines may also be investigated as potential therapeutic drugs in Alzheimer’s disease (AD) and in diseases involving abnormal pre-mRNA splicing.