Current therapies for diseases of heart muscle (cardiomyopathy) and aorta (aortopathy) include inhibitors of the renin-angiotensin system, β-adrenergic antagonists, and the statin class of cholesterol-lowering agents. These therapies have limited efficacy, as adverse cardiovascular events continue to occur with some frequency in patients taking these drugs. Although cardiomyopathy and aortopathy can coexist in a number of conditions (for example, Marfan's syndrome, acromegaly, pregnancy, and aging), pathogenetic molecular links between the two Copyright 2010 by the American Association for the Advancement of Science; all rights reserved. † To whom correspondence should be addressed. mukesh.jain2@case.edu. * These authors contributed equally to this work. SUPPLEMENTARY MATERIALwww.sciencetranslationalmedicine.org/cgi/content/full/2/26/26ra26/DC1 Fig. S1. Cardiovascular abnormalities in AngII-treated mice and cultured cells. Fig. S2. Baseline abnormalities in Klf15 −/− heart and aorta. Fig. S3. Cardiac mass and systolic blood pressure after AngII infusion. Fig. S4. Histologic parameters in aortas. Fig. S5. MMP-3 abundance in aortic smooth muscle. Fig. S6. p53 mRNA concentrations in heart and aortic tissue. Fig. S7. p300 abundance in hearts, curcumin administration protocol, and aortic morphometry after curcumin therapy. Table S1. Baseline cardiac parameters in Klf15 −/− and wild-type mice. Table S2. Cardiac parameters in Klf15 −/− and wild-type mice after AngII infusion. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript diseases remain poorly understood. We reasoned that identification of common molecular perturbations in these two tissues could point to therapies for both conditions. Here, we show that deficiency of the transcriptional regulator Kruppel-like factor 15 (Klf15) in mice leads to both heart failure and aortic aneurysm formation through a shared molecular mechanism. Klf15 concentrations are markedly reduced in failing human hearts and in human aortic aneurysm tissues. Mice deficient in Klf15 develop heart failure and aortic aneurysms in a p53-dependent and p300 acetyltransferase-dependent fashion. KLF15 activation inhibits p300-mediated acetylation of p53. Conversely, Klf15 deficiency leads to hyperacetylation of p53 in the heart and aorta, a finding that is recapitulated in human tissues. Finally, Klf15-deficient mice are rescued by p53 deletion or p300 inhibition. These findings highlight a molecular perturbation common to the pathobiology of heart failure and aortic aneurysm formation and suggest that manipulation of KLF15 function may be a productive approach to treat these morbid diseases.

SUMMARY Diurnal variation in nitrogen homeostasis is observed across phylogeny. But whether these are endogenous rhythms, and if so, molecular mechanisms that link nitrogen homeostasis to the circadian clock remain unknown. Here, we provide evidence that a clock-dependent peripheral oscillator, Krüppel-like factor15 transcriptionally coordinates rhythmic expression of multiple enzymes involved in mammalian nitrogen homeostasis. In particular, Krüppel-like factor15-deficient mice exhibit no discernable amino acid rhythm, and the rhythmicity of ammonia to urea detoxification is impaired. Of the external cues, feeding plays a dominant role in modulating Krüppel-like factor15 rhythm and nitrogen homeostasis. Further, when all behavioral, environmental and dietary cues were controlled in humans, nitrogen homeostasis still expressed endogenous circadian rhythmicity. Thus, in mammals, nitrogen homeostasis exhibits circadian rhythmicity, and is orchestrated by Krüppel-like factor15.

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