title: Myocardial Hypertrophic Remodeling and Impaired Left Ventricular Function in Mice with a Cardiac-Specific Deletion of Janus Kinase 2.
abstract: The Janus kinase (JAK) system is involved in numerous cell signaling processes and is highly expressed in cardiac tissue. The JAK isoform JAK2 is activated by numerous factors known to influence cardiac function and pathologic conditions. However, although abundant, the role of JAK2 in the regulation or maintenance of cardiac homeostasis remains poorly understood. Using the Cre-loxP system, we generated a cardiac-specific deletion of Jak2 in the mouse to assess the effect on cardiac function with animals followed up for a 4-month period after birth. These animals had marked mortality during this period, although at 4 months mortality in male mice (47%) was substantially higher compared with female mice (30%). Both male and female cardiac Jak2-deleted mice had hypertrophy, dilated cardiomyopathy, and severe left ventricular dysfunction, including a marked reduction in ejection fractions as assessed by serial echocardiography, although the responses in females were somewhat less severe. Defective cardiac function was associated with altered protein levels of sarcoplasmic reticulum calcium-regulatory proteins particularly in hearts from male mice that had depressed levels of SERCA2 and phosphorylated phospholamban. In contrast, SERCA2 was unchanged in hearts of female mice, whereas phosphorylated phospholamban was increased. Our findings suggest that cardiac JAK2 is critical for maintaining normal heart function, and its ablation produces a severe pathologic phenotype composed of myocardial remodeling, heart failure, and pronounced mortality.
authors.affiliation: Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
authors.forename: Xiaohong T
authors.initials: XT
authors.lastname: Gan
authors.affiliation: Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
authors.forename: Venkatesh
authors.initials: V
authors.lastname: Rajapurohitam
authors.affiliation: Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
authors.forename: Jenny
authors.initials: J
authors.lastname: Xue
authors.affiliation: Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
authors.forename: Cathy
authors.initials: C
authors.lastname: Huang
authors.affiliation: Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
authors.forename: Suresh
authors.initials: S
authors.lastname: Bairwa
authors.affiliation: Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
authors.forename: Xilan
authors.initials: X
authors.lastname: Tang
authors.affiliation: Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
authors.forename: Jeffrey T-Y
authors.initials: JT
authors.lastname: Chow
authors.affiliation: Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
authors.forename: Melissa F W
authors.initials: MF
authors.lastname: Liu
authors.affiliation: Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
authors.forename: Felix
authors.initials: F
authors.lastname: Chiu
authors.affiliation: Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Nebraska Medical Center, Omaha, Nebraska.
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Sakamoto
authors.affiliation: Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Nebraska Medical Center, Omaha, Nebraska.
authors.forename: Kay-Uwe
authors.initials: KU
authors.lastname: Wagner
authors.affiliation: Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada. Electronic address: morris.karmazyn@schulich.uwo.ca.
authors.forename: Morris
authors.initials: M
authors.lastname: Karmazyn
mesh_terms: D000818:Animals; D006332:Cardiomegaly / Q000201:enzymology* / Q000235:genetics / Q000473:pathology / Q000503:physiopathology; D005260:Female; D017353:Gene Deletion; D005838:Genotype; D053614:Janus Kinase 2 / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D008297:Male; D018345:Mice, Knockout; D018487:Ventricular Dysfunction, Left / Q000201:enzymology* / Q000235:genetics / Q000473:pathology / Q000503:physiopathology; D020257:Ventricular Remodeling / Q000235:genetics / Q000502:physiology*
chemical_list: C507926:Jak2 protein, mouse; D053614:Janus Kinase 2