title: Rubicon deficiency enhances cardiac autophagy and protects mice from lipopolysaccharide-induced lethality and reduction in stroke volume.
abstract: : Rubicon has been suggested to suppress autophagosome maturation by negatively regulating PI3KC3/Vps34 activity. However, the physiological function of Rubicon remains elusive. We hypothesized that Rubicon deficiency enhances autophagic flux in the heart and affects cardiac function. Rubicon knockout (KO) mice were generated by piggyBac transposition. Loss of Rubicon was demonstrated at both mRNA and protein levels. Rubicon KO mice were born in Mendelian ratios. Autophagic flux, assessed by bafilomycin A1-induced changes in LC3 II protein abundance, was enhanced in the heart of Rubicon KO mice compared with wild-type (WT) controls. Hematoxylin-eosin staining and picrosirius red staining showed that Rubicon KO mice exhibited normal baseline cardiac morphology. Echocardiography revealed that ejection fraction and fractional shortening, 2 indices of cardiac function, were comparable between Rubicon KO mice at 2, 8, and 12 months of age (n = 6-8 for each age group) and the corresponding WT controls (n = 6-8 for each age group). In a mouse model of lipopolysaccharide (LPS)-induced sepsis, the survival time of LPS-treated Rubicon KO mice (n = 10) was prolonged compared with LPS-treated WT controls (n = 11). Echocardiography revealed that Rubicon deficiency partially normalized LPS-induced reduction in stroke volume and cardiac output 12 hours after LPS administration compared with LPS-treated WT controls (n = 6 for each group). Autophagic flux was enhanced in Rubicon-deficient hearts 12 hours after LPS treatment compared with LPS-treated WT controls. Real-time quantitative polymerase chain reaction suggested that proinflammatory cytokine expression was not significantly different between LPS-treated Rubicon KO mice and WT controls (n = 3 for each group). Our data demonstrate for the first time that Rubicon deficiency enhances autophagic flux in the heart and protects mice from lethality and reduction in stroke volume induced by LPS.
authors.affiliation: *Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai, China; and †Institutes of Biomedical Sciences, Fudan University, Shanghai, China.
authors.forename: Zhenguo
authors.initials: Z
authors.lastname: Zi
authors.forename: Zongpei
authors.initials: Z
authors.lastname: Song
authors.forename: Shasha
authors.initials: S
authors.lastname: Zhang
authors.forename: Yong
authors.initials: Y
authors.lastname: Ye
authors.forename: Can
authors.initials: C
authors.lastname: Li
authors.forename: Mingqing
authors.initials: M
authors.lastname: Xu
authors.forename: Yunzeng
authors.initials: Y
authors.lastname: Zou
authors.forename: Lin
authors.initials: L
authors.lastname: He
authors.forename: Hongxin
authors.initials: H
authors.lastname: Zhu
mesh_terms: D000818:Animals; D001343:Autophagy; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D005786:Gene Expression Regulation; D005838:Genotype; D006331:Heart Diseases / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D018836:Inflammation Mediators / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000172:deficiency* / Q000235:genetics; D008070:Lipopolysaccharides; D018345:Mice, Knockout; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D010641:Phenotype; D012333:RNA, Messenger / Q000378:metabolism; D018805:Sepsis / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D013318:Stroke Volume; D013997:Time Factors
chemical_list: D016207:Cytokines; D018836:Inflammation Mediators; D047908:Intracellular Signaling Peptides and Proteins; D008070:Lipopolysaccharides; D012333:RNA, Messenger; C000601571:Rubcn protein, mouse