Cardiac-specific ß-catenin deletion dysregulates energetic metabolism and mitochondrial function in perinatal cardiomyocytes.

ß-Catenin signaling pathway regulates cardiomyocytes proliferation and differentiation, though its involvement in metabolic regulation of cardiomyocytes remains unknown. We used one-day-old mice with cardiac-specific knockout of ß-catenin and neonatal rat ventricular myocytes treated with ß-catenin inhibitor to investigate the role of ß-catenin metabolism regulation in perinatal cardiomyocytes. Transcriptomics of perinatal ß-catenin-ablated hearts revealed a dramatic shift in the expression of genes involved in metabolic processes. Further analysis indicated an inhibition of lipolysis and glycolysis in both in vitro and in vivo models. Finally, we showed that ß-catenin deficiency leads to mitochondria dysfunction via the downregulation of Sirt1/PGC-1α pathway. We conclude that cardiac-specific ß-catenin ablation disrupts the energy substrate shift that is essential for postnatal heart maturation, leading to perinatal lethality of homozygous ß-catenin knockout mice.

Brain plasticity after ischemic episode.

Brain plasticity describes the potential of the organ for adaptive changes involved in various phenomena in health and disease. A substantial amount of experimental evidence, received in animal and cell models, shows that a cascade of plastic changes at the molecular, cellular, and tissue levels, is initiated in different regions of the postischemic brain. Underlying mechanisms include neurochemical alterations, functional changes in excitatory and inhibitory synapses, axonal and dendritic sprouting, and reorganization of sensory and motor central maps. Multiple lines of evidence indicate numerous points in which the process of postischemic recovery may be influenced with the aim to restore the full capacity of the brain tissue injured by an ischemic episode.

Structural features of ischemic damage in the hippocampus.

Cerebral ischemic injury resulting from either focal or global circulatory arrests in the brain is one of the major causes of death and disability in the adult population. The hippocampus, playing important roles in learning and memory, is selectively vulnerable to ischemic insults. Distinct populations of hippocampal neurons are targeted by ischemia and multiple factors, including excitotoxicity, oxidative stress, and inflammation, are responsible for their damage and death. Modifications of synapses occur very early after ischemia, reflecting related changes in synaptic transmission. These modifications structurally relate to spatial patterns formed by synaptic vesicles, geometry of postsynaptic density, and so forth. Ischemia-induced changes of synaptic contacts can be implicated in the mechanisms leading to delayed neuronal death. In this review, we summarize the available data on the structural aspects of ischemic injury of the hippocampus obtained in tissue culture and animal models and discuss pathways of neurodegeneration common for cerebral ischemia and various neurodegenerative disorders.