Gabor Czibik1,2, Zaineb Mezdari1, Dogus Murat Altintas1, Daigo Sawaki1, Geneviève Derumeaux1,2, Juliette Bréhat1, Maria Pini1, Thomas d'Humières1,2, Thaïs Delmont1, Costin Radu1,3, Marielle Breau1, Hao Liang1, Cecile Martel4, Azania Abatan1, Rizwan Sarwar5, Ophélie Marion1, Suzain Naushad1, Yanyan Zhang1, Maissa Halfaoui1, Nadine Suffee6,7, Didier Morin1, Serge Adnot1,2, Stéphane Hatem6,7, Arash Yavari5,8. 1. INSERM (L'Institut National de la Santé et de la Recherche Médicale) U955 (G.C., Z.M., D.M.A., J.B., M.P., T.d'H., T.D., C.R., M.B., H.L., A.A., O.M., S.N., Y.Z., M.H., D.M., S.A., D.S., G.D.), Université Paris-Est Créteil, France. 2. Department of Physiology (G.C., T.d'H., S.A., G.D.), AP-HP, Henri Mondor Hospital, FHU-SENEC, Créteil, France. 3. Department of Cardiac Surgery (C.R.), AP-HP, Henri Mondor Hospital, FHU-SENEC, Créteil, France. 4. Mitologics SAS (C.M.), Université Paris-Est Créteil, France. 5. Experimental Therapeutics, Radcliffe Department of Medicine (R.S., A.Y.), University of Oxford, United Kingdom. 6. Sorbonne Universités, INSERM UMR_S1166, Faculté de Médecine UPMC, Paris, France (N.S., S.H.). 7. Institute of Cardiometabolism and Nutrition, ICAN, Paris, France (N.S., S.H.). 8. Wellcome Centre for Human Genetics (A.Y.), University of Oxford, United Kingdom.
Abstract
BACKGROUND: Aging myocardium undergoes progressive cardiac hypertrophy and interstitial fibrosis with diastolic and systolic dysfunction. Recent metabolomics studies shed light on amino acids in aging. The present study aimed to dissect how aging leads to elevated plasma levels of the essential amino acid phenylalanine and how it may promote age-related cardiac dysfunction. METHODS: We studied cardiac structure and function, together with phenylalanine catabolism in wild-type (WT) and p21-/- mice (male; 2-24 months), with the latter known to be protected from cellular senescence. To explore phenylalanine's effects on cellular senescence and ectopic phenylalanine catabolism, we treated cardiomyocytes (primary adult rat or human AC-16) with phenylalanine. To establish a role for phenylalanine in driving cardiac aging, WT male mice were treated twice a day with phenylalanine (200 mg/kg) for a month. We also treated aged WT mice with tetrahydrobiopterin (10 mg/kg), the essential cofactor for the phenylalanine-degrading enzyme PAH (phenylalanine hydroxylase), or restricted dietary phenylalanine intake. The impact of senescence on hepatic phenylalanine catabolism was explored in vitro in AML12 hepatocytes treated with Nutlin3a (a p53 activator), with or without p21-targeting small interfering RNA or tetrahydrobiopterin, with quantification of PAH and tyrosine levels. RESULTS: Natural aging is associated with a progressive increase in plasma phenylalanine levels concomitant with cardiac dysfunction, whereas p21 deletion delayed these changes. Phenylalanine treatment induced premature cardiac deterioration in young WT mice, strikingly akin to that occurring with aging, while triggering cellular senescence, redox, and epigenetic changes. Pharmacological restoration of phenylalanine catabolism with tetrahydrobiopterin administration or dietary phenylalanine restriction abrogated the rise in plasma phenylalanine and reversed cardiac senescent alterations in aged WT mice. Observations from aged mice and human samples implicated age-related decline in hepatic phenylalanine catabolism as a key driver of elevated plasma phenylalanine levels and showed increased myocardial PAH-mediated phenylalanine catabolism, a novel signature of cardiac aging. CONCLUSIONS: Our findings establish a pathogenic role for increased phenylalanine levels in cardiac aging, linking plasma phenylalanine levels to cardiac senescence via dysregulated phenylalanine catabolism along a hepatic-cardiac axis. They highlight phenylalanine/PAH modulation as a potential therapeutic strategy for age-associated cardiac impairment.
BACKGROUND: Aging myocardium undergoes progressive cardiac hypertrophy and interstitial fibrosis with diastolic and systolic dysfunction. Recent metabolomics studies shed light on amino acids in aging. The present study aimed to dissect how aging leads to elevated plasma levels of the essential amino acid phenylalanine and how it may promote age-related cardiac dysfunction. METHODS: We studied cardiac structure and function, together with phenylalanine catabolism in wild-type (WT) and p21-/- mice (male; 2-24 months), with the latter known to be protected from cellular senescence. To explore phenylalanine's effects on cellular senescence and ectopic phenylalanine catabolism, we treated cardiomyocytes (primary adult rat or human AC-16) with phenylalanine. To establish a role for phenylalanine in driving cardiac aging, WT male mice were treated twice a day with phenylalanine (200 mg/kg) for a month. We also treated aged WT mice with tetrahydrobiopterin (10 mg/kg), the essential cofactor for the phenylalanine-degrading enzyme PAH (phenylalanine hydroxylase), or restricted dietary phenylalanine intake. The impact of senescence on hepatic phenylalanine catabolism was explored in vitro in AML12 hepatocytes treated with Nutlin3a (a p53 activator), with or without p21-targeting small interfering RNA or tetrahydrobiopterin, with quantification of PAH and tyrosine levels. RESULTS: Natural aging is associated with a progressive increase in plasma phenylalanine levels concomitant with cardiac dysfunction, whereas p21 deletion delayed these changes. Phenylalanine treatment induced premature cardiac deterioration in young WT mice, strikingly akin to that occurring with aging, while triggering cellular senescence, redox, and epigenetic changes. Pharmacological restoration of phenylalanine catabolism with tetrahydrobiopterin administration or dietary phenylalanine restriction abrogated the rise in plasma phenylalanine and reversed cardiac senescent alterations in aged WT mice. Observations from aged mice and human samples implicated age-related decline in hepatic phenylalanine catabolism as a key driver of elevated plasma phenylalanine levels and showed increased myocardial PAH-mediated phenylalanine catabolism, a novel signature of cardiac aging. CONCLUSIONS: Our findings establish a pathogenic role for increased phenylalanine levels in cardiac aging, linking plasma phenylalanine levels to cardiac senescence via dysregulated phenylalanine catabolism along a hepatic-cardiac axis. They highlight phenylalanine/PAH modulation as a potential therapeutic strategy for age-associated cardiac impairment.