Lipid droplets (LDs) are intracellular organelles that provide fatty acids (FAs) to cellular processes including synthesis of membranes and production of metabolic energy. While known to move bidirectionally along microtubules (MTs), the role of LD motion and whether it facilitates interaction with other organelles are unclear. Here we show that during nutrient starvation, LDs and mitochondria relocate on detyrosinated MT from the cell centre to adopt a dispersed distribution. In the cell periphery, LD–mitochondria interactions increase and LDs efficiently supply FAs for mitochondrial beta-oxidation. This cellular adaptation requires the activation of the energy sensor AMPK, which in response to starvation simultaneously increases LD motion, reorganizes the network of detyrosinated MTs and activates mitochondria. In conclusion, we describe the existence of a specialized cellular network connecting the cellular energetic status and MT dynamics to coordinate the functioning of LDs and mitochondria during nutrient scarcity.

FGF21 is an endocrine factor that contributes to multiple pathophysiological processes, mainly via its action as a metabolic regulator and cardioprotective agent. Recent studies have shown increased circulating FGF21 levels in hypertensive patients and in mouse models of hypertension. However, the relevance of FGF21 in hypertensive heart disease has not been addressed. Hypertension was induced by treating 4‐month old WT and Fgf21−/− mice with angiotensin II (AngII) for 1 week, resulting in a similar increase in blood pressure in both genotypes. Plasma FGF21 levels and expression in heart and liver were significantly increased in hypertensive WT mice relative to controls, an effect that was associated with increased expression levels of β‐klotho specifically in the heart. Fgf21−/− mice developed a greater degree of hypertensive heart disease than WT mice, notably characterized by extensive cardiac dysfunction and fibrosis. In vitro and in vivo studies further showed that FGF21 exerted a marked protective effect against cardiac fibrosis. Finally, left ventricle biopsies from human hypertensive heart donors, especially those developing cardiomyopathy, showed a significant increase in FGF21expression compared with normotensive controls, a finding that was associated with significantly enhanced cardiac hypertrophy and fibrosis. We conclude that during hypertension, both systemic and cardiac‐produced FGF21 are induced and act on the heart, protecting it from hypertensive heart disease. Thus, FGF21 acts as key factor in the fibrogenesis associated with hypertensive heart disease. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Alcoholic cardiomyopathy (ACM) resulting from chronic alcohol misuse is one of the main contributors leading to heart failure and cardiovascular mortality. Fibroblast growth factor 21 (FGF21) is a well‐established cardioprotective factor. We aimed to study the role of FGF21 in experimentally induced models and clinical affected patients with cardiac damage due to chronic alcohol consumption. We found that circulating FGF21 levels and cardiac FGF21 and β‐klotho protein levels were increased in subjects with chronic alcohol consumption. As an experimental model of ACM, we fed wild‐type and Fgf21 knockout (Fgf21−/−) mice with a 4% alcohol liquid diet for 4 and 12 weeks. FGF21 circulating levels and FGF21 expression in the myocardium were also increased in wild‐type mice after chronic alcohol intake. Fgf21−/− mice develop a higher degree of cardiac hypertrophy, fibrosis, and cardiac dysfunction after chronic alcohol consumption than wild‐type mice. Moreover, the myocardium of Fgf21−/− mice showed signs of metabolic deregulation, oxidative stress, and mitochondrial dysfunction after alcohol intake. Finally, human cardiac biopsies from patients with chronic alcohol consumption developing ACM presented a higher degree of oxidative stress which positively correlated with the FGF21 protein levels in the myocardium. We conclude that plasma levels and cardiac myocyte FGF21 expression were induced in response to chronic alcohol consumption. The lack of FGF21 aggravated cardiac damage produced by ACM, in association with enhanced mitochondrial and oxidative stress, thus pointing to FGF21 as a protective agent against development of alcohol‐induced cardiomyopathy. © 2020 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Meteorin-like/Meteorin-β (Metrnl/Metrnβ) is a secreted protein produced by skeletal muscle and adipose tissue that exerts metabolic actions that improve glucose metabolism. The role of Metrnβ in cardiac disease is completely unknown. Here, we show that Metrnβ-null mice exhibit asymmetrical cardiac hypertrophy, fibrosis, and enhanced signs of cardiac dysfunction in response to isoproterenol-induced cardiac hypertrophy and aging. Conversely, adeno-associated virus–mediated specific overexpression of Metrnβ in the heart prevents the development of cardiac remodeling. Furthermore, Metrnβ inhibits cardiac hypertrophy development in cardiomyocytes in vitro, indicating a direct effect on cardiac cells. Antibody-mediated blockage of Metrnβ in cardiomyocyte cell cultures indicated an autocrine action of Metrnβ on the heart, in addition to an endocrine action. Moreover, Metrnβ is highly produced in the heart, and analysis of circulating Metrnβ concentrations in a large cohort of patients reveals that it is a new biomarker of heart failure with an independent prognostic value.