Development of a Novel Perfusable Solution for Preservation: Towards Photosynthetic Oxygenation for Organ Transplantation.

Oxygen is the key molecule for aerobic metabolism, but no animal cells can produce it, creating an extreme dependency on external supply. In contrast, microalgae are photosynthetic microorganisms, therefore, they are able to produce oxygen as plant cells do. As hypoxia is one of the main issues in organ transplantation, especially during preservation, the main goal of this work was to develop the first generation of perfusable photosynthetic solutions, exploring its feasibility for organ preservation.

A physiologic rise in cytoplasmic calcium ion signal increases pannexin1 channel activity via a C-terminus phosphorylation by CaMKII.

Pannexin1 (Panx1) channels are ubiquitously expressed in vertebrate cells and are widely accepted as adenosine triphosphate (ATP)-releasing membrane channels. Activation of Panx1 has been associated with phosphorylation in a specific tyrosine residue or cleavage of its C-terminal domains. In the present work, we identified a residue (S394) as a putative phosphorylation site by Ca/calmodulin-dependent kinase II (CaMKII).

Stretch-Induced Activation of Pannexin 1 Channels Can Be Prevented by PKA-Dependent Phosphorylation.

Pannexin 1 channels located in the cell membrane are permeable to ions, metabolites, and signaling molecules. While the activity of these channels is known to be modulated by phosphorylation on T198, T308, and S206, the possible involvement of other putative phosphorylation sites remains unknown. Here, we describe that the activity of Panx1 channels induced by mechanical stretch is reduced by adenosine via a PKA-dependent pathway.

Blockade of Hemichannels Normalizes the Differentiation Fate of Myoblasts and Features of Skeletal Muscles from Dysferlin-Deficient Mice.

Dysferlinopathies are muscle dystrophies caused by mutations in the gene encoding dysferlin, a relevant protein for membrane repair and trafficking. These diseases are untreatable, possibly due to the poor knowledge of relevant molecular targets. Previously, we have shown that human myofibers from patient biopsies as well as myotubes derived from immortalized human myoblasts carrying a mutated form of dysferlin express connexin proteins, but their relevance in myoblasts fate and function remained unknown.

Vitamin E Blocks Connexin Hemichannels and Prevents Deleterious Effects of Glucocorticoid Treatment on Skeletal Muscles.

Glucocorticoids are frequently used as anti-inflammatory and immunosuppressive agents. However, high doses and/or prolonged use induce undesired secondary effects such as muscular atrophy. Recently, de novo expression of connexin43 and connexin45 hemichannels (Cx43 HCs and Cx45 HCs, respectively) has been proposed to play a critical role in the mechanism underlying myofiber atrophy induced by dexamethasone (Dex: a synthetic glucocorticoid), but their involvement in specific muscle changes promoted by Dex remains poorly understood.

Active acetylcholine receptors prevent the atrophy of skeletal muscles and favor reinnervation.

Denervation of skeletal muscles induces severe muscle atrophy, which is preceded by cellular alterations such as increased plasma membrane permeability, reduced resting membrane potential and accelerated protein catabolism. The factors that induce these changes remain unknown. Conversely, functional recovery following denervation depends on successful reinnervation.

De novo expression of functional connexins 43 and 45 hemichannels increases sarcolemmal permeability of skeletal myofibers during endotoxemia.

Endotoxemia caused by bacterial lipopolysaccharides (LPSs) leads to severe skeletal muscular deterioration, starting with higher membrane permeability and decline in resting membrane potential (RMP). However, the molecular mechanism of such changes remains unclear. Here, we evaluated the possible involvement of connexin43- and connexin45-based hemichannels (Cx43 and Cx45 HCs, respectively) as putative mediators of sarcolemmal dysfunctions induced by LPS in control (Cx43Cx45) and Cx43/Cx45 expression-deficient (Cx43Cx45:Myo-Cre) skeletal mice myofibers.

Sepsis-Induced Channelopathy in Skeletal Muscles is Associated with Expression of Non-Selective Channels.

Skeletal muscles (∼50% of the body weight) are affected during acute and late sepsis and represent one sepsis associate organ dysfunction. Cell membrane changes have been proposed to result from a channelopathy of yet unknown cause associated with mitochondrial dysfunction and muscle atrophy. We hypothesize that the channelopathy might be explained at least in part by the expression of non-selective channels.

Dexamethasone-induced muscular atrophy is mediated by functional expression of connexin-based hemichannels.

Long-term treatment with high glucocorticoid doses induces skeletal muscle atrophy. However, the molecular mechanism of such atrophy remains unclear. We evaluated the possible involvement of connexin-based hemichannels (Cx HCs) in muscle atrophy induced by dexamethasone (DEX), a synthetic glucocorticoid, on control (Cx43(fl/fl)Cx45(fl/fl)) and Cx43/Cx45 expression-deficient (Cx43(fl/fl)Cx45(fl/fl):Myo-Cre) skeletal myofibers.

Fast skeletal myofibers of mdx mouse, model of Duchenne muscular dystrophy, express connexin hemichannels that lead to apoptosis.

Skeletal muscles of patients with Duchenne muscular dystrophy (DMD) show numerous alterations including inflammation, apoptosis, and necrosis of myofibers. However, the molecular mechanism that explains these changes remains largely unknown. Here, the involvement of hemichannels formed by connexins (Cx HCs) was evaluated in skeletal muscle of mdx mouse model of DMD.

Neural progenitor cells isolated from the subventricular zone present hemichannel activity and form functional gap junctions with glial cells.

The postnatal subventricular zone (SVZ) lining the walls of the lateral ventricles contains neural progenitor cells (NPCs) that generate new olfactory bulb interneurons. Communication via gap junctions between cells in the SVZ is involved in NPC proliferation and in neuroblast migration towards the olfactory bulb. SVZ NPCs can be expanded in vitro in the form of neurospheres that can be used for transplantation purposes after brain injury.

Stromal-epithelial cell interactions and androgen receptor-coregulator recruitment is altered in the tissue microenvironment of prostate cancer.

Tissue recombination experiments show that prostate mesenchyma directs prostate epithelial cell growth and development in an androgen-dependent manner, and that functional differentiation of prostate epithelium requires androgen-driven processes in both epithelia and stroma. The androgen induction of target genes in primary cultures of prostate stromal and epithelial cells was determined using an adenoviral expression system, which employed the MMTV-enhancer driven luciferase reporter as an androgen receptor (AR)-mediated transcription assay. These studies indicate that both cell types contain functional AR.