A Novel Zak Knockout Mouse with a Defective Ribotoxic Stress Response

• Main Authors: Dakshina M. Jandhyala, John Wong, Nicholas J. Mantis, Bruce E. Magun, John M. Leong, Cheleste M. Thorpe
• Format: Article
• Language: English
• Published: MDPI AG 2016-09-01
• Series: Toxins
• Subjects: ZAK; MAP3K; Ricin; Ribotoxic Stress Response; protein synthesis inhibition; p38; JNK1/2; inflammation; murine; macrophage
• Online Access: http://www.mdpi.com/2072-6651/8/9/259

Ricin activates the proinflammatory ribotoxic stress response through the mitogen activated protein 3 kinase (MAP3K) ZAK, resulting in activation of mitogen activated protein kinases (MAPKs) p38 and JNK1/2. We had a novel zak−/− mouse generated to study the role of ZAK signaling in vivo during ricin intoxication. To characterize this murine strain, we intoxicated zak−/− and zak+/+ bone marrow–derived murine macrophages with ricin, measured p38 and JNK1/2 activation by Western blot, and measured zak, c-jun, and cxcl-1 expression by qRT-PCR. To determine whether zak−/− mice differed from wild-type mice in their in vivo response to ricin, we performed oral ricin intoxication experiments with zak+/+ and zak−/− mice, using blinded histopathology scoring of duodenal tissue sections to determine differences in tissue damage. Unlike macrophages derived from zak+/+ mice, those derived from the novel zak−/− strain fail to activate p38 and JNK1/2 and have decreased c-jun and cxcl-1 expression following ricin intoxication. Furthermore, compared with zak+/+ mice, zak−/− mice have decreased duodenal damage following in vivo ricin challenge. zak−/− mice demonstrate a distinct ribotoxic stress–associated phenotype in response to ricin and therefore provide a new animal model for in vivo studies of ZAK signaling.