Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)

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Tschöpe, C. et al.

Tschöpe, Spillmann, Rehfeld, Koch, Westermann, Altmann, Dendorfer, Walther, Bader, Paul, Schultheiss, Vetter,

Improvement of defective sarcoplasmic reticulum Ca2+ transport in diabetic heart of transgenic rats expressing the human kallikrein-1 gene.

The bradykinin-forming enzyme kallikrein-1 is expressed in the heart. To examine whether contractile performance and sarcoplasmic reticulum Ca2+ transport of the diabetic heart can be rescued by targeting the kallikrein-kinin system, we studied left ventricular function and sarcoplasmic reticular Ca2+ uptake after induction of streptozotocin-induced diabetes mellitus in transgenic rats expressing the human tissue kallikrein-1 gene. Six weeks after a single injection of either streptozotocin (70 mg/kg ip) or vehicle, left ventricular performance was determined using a Millar-Tip catheter system. The Ca2+-transporting activity of reticulum-derived membrane vesicles was determined in left ventricular homogenates as oxalate-supported 45Ca2+ uptake. Western blot analysis was used to quantify the reticular Ca2+-ATPase SERCA2a, phospholamban, and the phosphorylation status of the latter. Contractile performance and Ca2+ uptake activity were similar in nondiabetic wild-type and transgenic rats. Severely diabetic wild-type animals exhibited impaired left ventricular performance and decreased reticular Ca2+ uptake (-39% vs. wild-type rats, P<0.05, respectively). These changes were attenuated in diabetic transgenic rats that, in addition, exhibited a markedly increased phospholamban phosphorylation at the Ca2+/calmodulin kinase-specific site threonine17 (2.2-fold vs. diabetic wild-type rats, P<0.05). These transgene-related effects were abolished after treatment with the bradykinin B2 receptor antagonist icatibant (Hoe 140). The SERCA2-to-phospholamban ratio, phosphoserine16-phospholamban levels, and the apparent affinity for Ca2+ of the uptake reaction did not differ between the groups. Increasing the activity of the kallikrein-kinin system by expressing a human kallikrein-1 transgene protects rat heart against diabetes-induced contractile and reticular Ca2+ transport dysfunctions. An increased phosphorylation of the SERCA2 regulatory protein phospholamban at threonine17 via a B2 receptor-mediated mechanism is thereby involved.[1]

References

Improvement of defective sarcoplasmic reticulum Ca2+ transport in diabetic heart of transgenic rats expressing the human kallikrein-1 gene. Tschöpe, C., Spillmann, F., Rehfeld, U., Koch, M., Westermann, D., Altmann, C., Dendorfer, A., Walther, T., Bader, M., Paul, M., Schultheiss, H.P., Vetter, R. FASEB J. (2004) [Pubmed]

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