An N-Ethyl-N-Nitrosourea (ENU)-Induced Dominant Negative Mutation in the JAK3 Kinase Protects against Cerebral Malaria Silayuv E. Bongfen1,4, Ian-Gael Rodrigue-Gervais2,4, Joanne Berghout1,4, Sabrina Torre3,4, Pablo Cingolani5, Sean A. Wiltshire3,4, Gabriel A. Leiva-Torres3,4, Louis Letourneau3, Robert Sladek3, Mathieu Blanchette5, Mark Lathrop6, Marcel A. Behr7,8, Samantha Gruenheid4,7, Silvia M. Vida3l,4, Maya Sal2e,,4h Philippe Gros1,3,4* 1 Department of Biochemistry, McGill University, Montreal, Canada, 2 Department of Medicine, McGill University, Montreal, Canada, 3 Department of Human Genetics, McGill University, Montreal, Canada, 4 Complex Traits Group, McGill University, Montreal, Canada, 5 School of Computer Science, McGill University, Montreal, Canada, 6 Institut de Ge´nomique, Centre National de Ge´notypage, Evry, France, 7 Department of Microbiology and Immunology, McGill University, Montreal, Canada, 8 The McGill University Health Center, Montreal, Canada Abstract Cerebral malaria (CM) is a lethal neurological complication of malaria. We implemented a genome-wide screen in mutagenized mice to identify host proteins involved in CM pathogenesis and whose inhibition may be of therapeutic value. One pedigree (P48) segregated a resistance trait whose CM-protective effect was fully penetrant, mapped to chromosome 8, and identified by genome sequencing as homozygosity for a mis-sense mutation (W81R) in the FERM domain of Janus- associated kinase 3 (Jak3). The causative effect of Jak3W81R was verified by complementation testing in Jak3W81R/2 double heterozygotes that were fully protected against CM. Jak3W81R homozygotes showed defects in thymic development with depletion of CD8+ T cell, B cell, and NK cell compartments, and defective T cell-dependent production of IFN-c. Adoptive transfer of normal splenocytes abrogates CM resistance in Jak3W81R homozygotes, an effect attributed to the CD8+ T cells. Jak3W81R behaves as a dominant negative variant, with significant CM resistance of Jak3W81R/+ heterozygotes, compared to CM-susceptible Jak3+/+ and Jak3+/2 controls. CM resistance in Jak3W81R/+ heterozygotes occurs in presence of normal T, B and NK cell numbers. These findings highlight the pathological role of CD8+ T cells and Jak3-dependent IFN-c-mediated Th1 responses in CM pathogenesis. Citation: Bongfen SE, Rodrigue-Gervais I-G, Berghout J, Torre S, Cingolani P, et al. (2012) An N-Ethyl-N-Nitrosourea (ENU)-Induced Dominant Negative Mutation in the JAK3 Kinase Protects against Cerebral Malaria. PLoS ONE 7(2): e31012. doi:10.1371/journal.pone.0031012 Editor: David R. Beier, Harvard Medical School, United States of America Received December 2, 2011; Accepted December 29, 2011; Published February 21, 2012 Copyright: 2012 Bongfen et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was supported by research grants to PG, MS, SV, MB from the Canadian Institutes of Health Research (CIHR; 216406), to SG, and MAB from the CIHR, and to ML from the European Union Framework 7 Program READNA (HEALTH-F4-2008-201418). RS is supported by a salary award from the Fonds De Recherche en Sante´ du Que´bec. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: philippe.gros@mcgill.ca Introduction Malaria, caused by infection with members of the Plasmodium family of parasites, still remains a global health problem, with close to 250 million clinical cases and almost a million deaths occurring each year, mostly in African children [1]. Cerebral malaria (CM) is the most severe complication of P. falciparum infection. Although CM develops in less than 1% of Plasmodium infected individuals, its sudden onset, rapid progression and limited treatment options (high dose quinine or artemisnin) contribute to an often-lethal outcome. CM is characterized by trapping of parasitized erythrocytes in the host microvasculature including the blood brain barrier (BBB) that triggers a strong inflammatory response in situ, vascular damage and hypoxia. Permeability of the BBB leads to seizures, paralysis, unrousable coma and death [2]. The cell and molecular pathways involved in CM pathogenesis are poorly characterized and need to be better understood to identify novel therapeutic targets for intervention. Clinical epidemiological studies in different geographical areas of malaria-endemicity have indicated that the onset, progression and outcome of CM involve a complex interplay between environmental factors, parasite-ex- pressed virulence factors and host genetic factors influencing replication of the parasite or innate or acquired immunity [3,4,5]. Genetic studies in humans have pointed to a heritable component to susceptibility to CM (reviewed in [6]), while case-control association studies have suggested a complex and heterogeneous genetic component in CM, including hemoglobin variants (hemoglobinopathies), polymorphisms in cytokine genes or gene promotors, and many others (reviewed by [3,4]). The complex genetic component of CM susceptibility has also been investigated in the mouse model for experimental CM caused by infection with Plasmodium berghei ANKA (PbA). P. berghei infection in mice closely mimics P. falciparum-induced CM in humans [7], with susceptible mouse strains (e.g. C57BL/6J, CBA/ J) developing an acute cerebral syndrome within 6–7 days characterized by ataxia, paraplegia, seizures and coma leading to uniform lethality by day 8–10 post-infection. Like in humans, studies in mouse mutants bearing inactivating mutations at specific PLoS ONE | www.plosone.org 1 February 2012 | Volume 7 | Issue 2 | e31012