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Abstract
Nicotinic acid adenine dinucleotide phosphate (NAADP) is a universal Ca2+ mobilizing second messenger essential for initiation of Ca2+ signaling. Recently, novel molecular mechanisms of both its rapid formation upon receptor stimulation and its mode of action were discovered. Dual NADPH oxidase 2 (DUOX2) and hematological and neurological expressed 1-like protein (HN1L)/Jupiter microtubule-associated homolog 2 (JPT2) were discovered as NAADP-forming enzyme and NAADP receptor/binding protein—the new kids on the block. These novel aspects are reviewed and integrated into the previous view of NAADP signaling.
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Di Fonso A, Pietrangelo L, D’Onofrio L, Michelucci A, Boncompagni S, Protasi F. Ageing Causes Ultrastructural Modification to Calcium Release Units and Mitochondria in Cardiomyocytes. Int J Mol Sci 2021; 22:8364. [PMID: 34445071 PMCID: PMC8395047 DOI: 10.3390/ijms22168364] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/20/2021] [Accepted: 07/28/2021] [Indexed: 12/12/2022] Open
Abstract
Ageing is associated with an increase in the incidence of heart failure, even if the existence of a real age-related cardiomyopathy remains controversial. Effective contraction and relaxation of cardiomyocytes depend on efficient production of ATP (handled by mitochondria) and on proper Ca2+ supply to myofibrils during excitation-contraction (EC) coupling (handled by Ca2+ release units, CRUs). Here, we analyzed mitochondria and CRUs in hearts of adult (4 months old) and aged (≥24 months old) mice. Analysis by confocal and electron microscopy (CM and EM, respectively) revealed an age-related loss of proper organization and disposition of both mitochondria and EC coupling units: (a) mitochondria are improperly disposed and often damaged (percentage of severely damaged mitochondria: adults 3.5 ± 1.1%; aged 16.5 ± 3.5%); (b) CRUs that are often misoriented (longitudinal) and/or misplaced from the correct position at the Z line. Immunolabeling with antibodies that mark either the SR or T-tubules indicates that in aged cardiomyocytes the sarcotubular system displays an extensive disarray. This disarray could be in part caused by the decreased expression of Cav-3 and JP-2 detected by western blot (WB), two proteins involved in formation of T-tubules and in docking SR to T-tubules in dyads. By WB analysis, we also detected increased levels of 3-NT in whole hearts homogenates of aged mice, a product of nitration of protein tyrosine residues, recognized as marker of oxidative stress. Finally, a detailed EM analysis of CRUs (formed by association of SR with T-tubules) points to ultrastructural modifications, i.e., a decrease in their frequency (adult: 5.1 ± 0.5; aged: 3.9 ± 0.4 n./50 μm2) and size (adult: 362 ± 40 nm; aged: 254 ± 60 nm). The changes in morphology and disposition of mitochondria and CRUs highlighted by our results may underlie an inefficient supply of Ca2+ ions and ATP to the contractile elements, and possibly contribute to cardiac dysfunction in ageing.
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Affiliation(s)
- Alessia Di Fonso
- CAST, Center for Advanced Studies and Technology, University G. d’Annunzio (Ud’A) of Chieti-Pescara, 66100 Chieti, Italy; (A.D.F.); (A.M.); (S.B.); (F.P.)
- DMSI, Department of Medicine and Aging Sciences, University G. d’Annunzio (Ud’A) of Chieti-Pescara, 66100 Chieti, Italy
| | - Laura Pietrangelo
- CAST, Center for Advanced Studies and Technology, University G. d’Annunzio (Ud’A) of Chieti-Pescara, 66100 Chieti, Italy; (A.D.F.); (A.M.); (S.B.); (F.P.)
- DMSI, Department of Medicine and Aging Sciences, University G. d’Annunzio (Ud’A) of Chieti-Pescara, 66100 Chieti, Italy
| | - Laura D’Onofrio
- IZSAM, Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise G. Caporale of Teramo, 64100 Teramo, Italy;
| | - Antonio Michelucci
- CAST, Center for Advanced Studies and Technology, University G. d’Annunzio (Ud’A) of Chieti-Pescara, 66100 Chieti, Italy; (A.D.F.); (A.M.); (S.B.); (F.P.)
| | - Simona Boncompagni
- CAST, Center for Advanced Studies and Technology, University G. d’Annunzio (Ud’A) of Chieti-Pescara, 66100 Chieti, Italy; (A.D.F.); (A.M.); (S.B.); (F.P.)
- DNICS, Department of Neuroscience, Imaging and Clinical Sciences, University G. d’Annunzio (Ud’A) of Chieti-Pescara, 66100 Chieti, Italy
| | - Feliciano Protasi
- CAST, Center for Advanced Studies and Technology, University G. d’Annunzio (Ud’A) of Chieti-Pescara, 66100 Chieti, Italy; (A.D.F.); (A.M.); (S.B.); (F.P.)
- DMSI, Department of Medicine and Aging Sciences, University G. d’Annunzio (Ud’A) of Chieti-Pescara, 66100 Chieti, Italy
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