Activation of Crtc2/Creb1 in skeletal muscle enhances weight loss during intermittent fasting

High-intensity training on CREB activation for improving brain health: a narrative review of possible molecular talks

Although physical exercise has obvious benefits in brain physiology, the molecular biomarkers induced by exercise protocols are inconclusive. Evidence indicates that exercise interventions are effective in shaping brain physiology. However, the potential mediator for improving brain functions is uncertain. CREB is one of the potential targets of exercise that triggers various molecular cross-talk to improve neurogenesis, long-term potentiation, and synaptogenesis. Therefore, CREB may be situated on the causal path between maintaining brain health and exercising. To support this, studies have shown that exercise-mediated CREB phosphorylation improves cognitive functions and memory. In addition, among the protocols of exercise (types, duration, and frequency), the intensity has been reported to be the most effective in triggering CREB-mediated molecular signaling. For example, HIT increases the synthesis of CREB, which may not only induce brain physiology but also induce brain pathology by higher activation of its downstream targets, such as BDNF. Therefore, this review aims to understand the effects of HIT on CREB function and how HIT can mediate the CREB-induced molecular cross-talk for maintaining brain health.

AAV-Mediated Expression of miR-17 Enhances Neurite and Axon Regeneration In Vitro

Neurodegenerative disorders, including traumatic injuries to the central nervous system (CNS) and neurodegenerative diseases, are characterized by early axonal damage, which does not regenerate in the adult mammalian CNS, leading to permanent neurological deficits. One of the primary causes of the loss of regenerative ability is thought to be a developmental decline in neurons' intrinsic capability for axon growth. Different molecules are involved in the developmental loss of the ability for axon regeneration, including many transcription factors. However, the function of microRNAs (miRNAs), which are also modulators of gene expression, in axon re-growth is still unclear. Among the various miRNAs recently identified with roles in the CNS, miR-17, which is highly expressed during early development, emerges as a promising target to promote axon regeneration. Here, we used adeno-associated viral (AAV) vectors to overexpress miR-17 (AAV.miR-17) in primary cortical neurons and evaluate its effects on neurite and axon regeneration in vitro. Although AAV.miR-17 had no significant effect on neurite outgrowth and arborization, it significantly enhances neurite regeneration after scratch lesion and axon regeneration after axotomy of neurons cultured in microfluidic chambers. Target prediction and functional annotation analyses suggest that miR-17 regulates gene expression associated with autophagy and cell metabolism. Our findings suggest that miR-17 promotes regenerative response and thus could mitigate neurodegenerative effects.

Asymmetric allostery in estrogen receptor-α homodimers drives responses to the ensemble of estrogens in the hormonal milieu

The estrogen receptor-α (ER) is thought to function only as a homodimer but responds to a variety of environmental, metazoan, and therapeutic estrogens at subsaturating doses, supporting binding mixtures of ligands as well as dimers that are only partially occupied. Here, we present a series of flexible ER ligands that bind to receptor dimers with individual ligand poses favoring distinct receptor conformations-receptor conformational heterodimers-mimicking the binding of two different ligands. Molecular dynamics simulations showed that the pairs of different ligand poses changed the correlated motion across the dimer interface to generate asymmetric communication between the dimer interface, the ligands, and the surface binding sites for epigenetic regulatory proteins. By examining the binding of the same ligand in crystal structures of ER in the agonist vs. antagonist conformers, we also showed that these allosteric signals are bidirectional. The receptor conformer can drive different ligand binding modes to support agonist vs. antagonist activity profiles, a revision of ligand binding theory that has focused on unidirectional signaling from the ligand to the coregulator binding site. We also observed differences in the allosteric signals between ligand and coregulator binding sites in the monomeric vs. dimeric receptor, and when bound by two different ligands, states that are physiologically relevant. Thus, ER conformational heterodimers integrate two different ligand-regulated activity profiles, representing different modes for ligand-dependent regulation of ER activity.

Biological functions of CRTC2 and its role in metabolism-related diseases

CREB-regulated transcription coactivator2 (CRTC2 or TORC2) is a transcriptional coactivator of CREB(cAMP response element binding protein), which affects human energy metabolism through cyclic adenosine phosphate pathway, Mammalian target of rapamycin (mTOR) pathway, Sterol regulatory element binding protein 1(SREBP1), Sterol regulatory element binding protein 2 (SREBP2) and other substances Current studies on CRTC2 mainly focus on glucose and lipid metabolism, relevant studies show that CRTC2 can participate in the occurrence and development of related diseases by affecting metabolic homeostasis. It has been found that Crtc2 acts as a signaling regulator for cAMP and Ca2 + signaling pathways in many cell types, and phosphorylation at ser171 and ser275 can regulate downstream biological functions by controlling CRTC2 shuttling between cytoplasm and nucleus.

Metabolism and exercise: the skeletal muscle clock takes centre stage

Circadian rhythms that influence mammalian homeostasis and overall health have received increasing interest over the past two decades. The molecular clock, which is present in almost every cell, drives circadian rhythms while being a cornerstone of physiological outcomes. The skeletal muscle clock has emerged as a primary contributor to metabolic health, as the coordinated expression of the core clock factors BMAL1 and CLOCK with the muscle-specific transcription factor MYOD1 facilitates the circadian and metabolic programme that supports skeletal muscle physiology. The phase of the skeletal muscle clock is sensitive to the time of exercise, which provides a rationale for exploring the interactions between the skeletal muscle clock, exercise and metabolic health. Here, we review the underlying mechanisms of the skeletal muscle clock that drive muscle physiology, with a particular focus on metabolic health. Additionally, we highlight the interaction between exercise and the skeletal muscle clock as a means of reinforcing metabolic health and discuss the possible implications of the time of exercise as a chronotherapeutic approach.

CORP: Gene delivery into murine skeletal muscle using in vivo electroporation

The strategy of gene delivery into skeletal muscles has provided exciting avenues in identifying new potential therapeutics towards muscular disorders and addressing basic research questions in muscle physiology through overexpression and knockdown studies. In vivo electroporation methodology offers a simple, rapidly effective technique for the delivery of plasmid DNA into post-mitotic skeletal muscle fibers and the ability to easily explore the molecular mechanisms of skeletal muscle plasticity. The purpose of this review is to describe how to robustly electroporate plasmid DNA into different hindlimb muscles of rodent models. Further, key parameters (e.g., voltage, hyaluronidase, plasmid concentration) which contribute to the successful introduction of plasmid DNA into skeletal muscle fibers will be discussed. In addition, details on processing tissue for immunohistochemistry and fiber cross-sectional area (CSA) analysis will be outlined. The overall goal of this review is to provide the basic and necessary information needed for successful implementation of in vivo electroporation of plasmid DNA and thus open new avenues of discovery research in skeletal muscle physiology.