Age-associated metabolic and epigenetic barriers during direct reprogramming of mouse fibroblasts into induced cardiomyocytes Francisco Santos, Magda Correia, Rafaela Dias, Bárbara Bola, Roberta Noberini, et al. Aging Cell, 2025 Heart disease is the leading cause of mortality in developed countries, and novel regenerative procedures are warranted. Direct cardiac conversion (DCC) of adult fibroblasts can create induced cardiomyocytes (iCMs) for gene and cell‐based heart therapy, and in addition to holding great promise, still lacks effectiveness as metabolic and age‐associated barriers remain elusive. Here, by employing MGT (Mef2c, Gata4, Tbx5) transduction of mouse embryonic fibroblasts (MEFs) and adult (dermal and cardiac) fibroblasts from animals of different ages, we provide evidence that the direct reprogramming of fibroblasts into iCMs decreases with age. Analyses of histone posttranslational modifications and ChIP‐qPCR revealed age‐dependent alterations in the epigenetic landscape of DCC. Moreover, DCC is accompanied by profound mitochondrial metabolic adaptations, including a lower abundance of anabolic metabolites, network remodeling, and reliance on mitochondrial respiration. In vitro metabolic modulation and dietary manipulation in vivo improve DCC efficiency and are accompanied by significant alterations in histone marks and mitochondrial homeostasis. Importantly, adult‐derived iCMs exhibit increased accumulation of oxidative stress in the mitochondria and activation of mitophagy or dietary lipids; they improve DCC and revert mitochondrial oxidative damage. Our study provides evidence that metaboloepigenetics plays a direct role in cell fate transitions driving DCC, highlighting the potential use of metabolic modulation to improve cardiac regenerative strategies.
RIPK3 dampens mitochondrial bioenergetics and lipid droplet dynamics in metabolic liver disease Marta B. Afonso, Tawhidul Islam, Julie Magusto, Ricardo Amorim, Véronique Lenoir, et al. Hepatology, 2023 Background and Aims: Receptor‐interacting protein kinase 3 (RIPK3) mediates NAFLD progression, but its metabolic function is unclear. Here, we aimed to investigate the role of RIPK3 in modulating mitochondria function, coupled with lipid droplet (LD) architecture in NAFLD. Approach and Results: Functional studies evaluating mitochondria and LD biology were performed in wild‐type (WT) and Ripk3 −/− mice fed a choline‐deficient, amino acid‐defined (CDAA) diet for 32 and 66 weeks and in CRISPR‐Cas9 Ripk3‐null fat‐loaded immortalized hepatocytes. The association between hepatic perilipin (PLIN) 1 and 5, RIPK3, and disease severity was also addressed in a cohort of patients with NAFLD and in PLIN1‐associated familial partial lipodystrophy. Ripk3 deficiency rescued impairment in mitochondrial biogenesis, bioenergetics, and function in CDAA diet–fed mice and fat‐loaded hepatocytes. Ripk3 deficiency was accompanied by a strong upregulation of antioxidant systems, leading to diminished oxidative stress upon fat loading both in vivo and in vitro. Strikingly, Ripk3 −/− hepatocytes displayed smaller size LD in higher numbers than WT cells after incubation with free fatty acids. Ripk3 deficiency upregulated adipocyte and hepatic levels of LD‐associated proteins PLIN1 and PLIN5. PLIN1 upregulation controlled LD structure and diminished mitochondrial stress upon free fatty acid overload in Ripk3 −/− hepatocytes and was associated with diminished human NAFLD severity. Conversely, a pathogenic PLIN1 frameshift variant was associated with NAFLD and fibrosis, as well as with increased hepatic RIPK3 levels in familial partial lipodystrophy. Conclusions: Ripk3 deficiency restores mitochondria bioenergetics and impacts LD dynamics. RIPK3 inhibition is promising in ameliorating NAFLD.
Bridging the gap between nature and antioxidant setbacks: Delivering caffeic acid to mitochondria José Teixeira, Pedro Soares, Sofia Benfeito, Michael P. Murphy, Paulo J. Oliveira, et al. Methods in Molecular Biology, 2015 As mitochondria have an important role as ATP supplier, cellular ROS producer and apoptosis regulator, these organelles are a promising target for pharmacological intervention in the treatment and management of several diseases. Consequently, research on mitochondria-targeted drugs, which exclude other intracellular structures or extracellular processes, is becoming a hot topic. One approach to address the specific targeting is to conjugate bioactive molecules to a lipophilic cation such as the triphenylphosphonium (TPP(+)). In this chapter, the development of a new antioxidant based on the dietary cinnamic acid-caffeic acid-is described as well as the demonstration of its mitochondriotropic activity.
