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Mitochondrial Responses (mitochondrial + response)

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Life Sciences	100%

Selected Abstracts

Mitochondrial Responses of Normal and Injured Human Skin Fibroblasts Following Low Level Laser Irradiation,An In Vitro Study

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2009
Innocent L. Zungu
Laser irradiation has proved to be very efficient in speeding and improving the quality of healing in pathological conditions of diverse etiologies. However, the mechanisms by which the beneficial effects are attained are not clear. Mitochondria are the primary phototargets during irradiation. The study aimed to establish if laser irradiation had an effect on hypoxic and acidotic cells. The study also aimed to use existing information regarding the possible mechanism of action (established in wounded cells) and apply these principles to acidic and hypoxic irradiated cells to determine whether laser has a stimulatory or inhibitory effect. Cell cultures were modified to simulate conditions of hypoxia (hypoxic gas mixture 95% N2 and 5% O2) and acidosis (pH 6.7) whereas the central scratch model was used to simulate a wound. Cells were irradiated with a helium,neon (632.8 nm, 3 mW cm,2) laser using 5 or 16 J cm,2 on days 1 and 4. Mitochondrial responses were measured 1 or 24 h after laser irradiation by assessing changes in mitochondrial membrane potential (MMP), cyclic AMP, intracellular Ca2+ and adenosine triphosphate (ATP) cell viability. Hypoxia and acidosis significantly reduced MMP when compared with normal nonirradiated control cells. Wounded, hypoxic and acidotic cells irradiated with 5 J cm,2 showed an increase in mitochondrial responses when compared with nonirradiated cells while 16 J cm,2 showed a significant decrease. The study confirmed that laser irradiation with 5 J cm,2 stimulated an increase in intracellular Ca2+ which resulted in an increase in MMP, ATP and cAMP, which ultimately results in photobiomodulation to restore homeostasis of injured cells. [source]

Functional and structural properties of stannin: Roles in cellular growth, selective toxicity, and mitochondrial responses to injury

JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2006
M.L. Billingsley
Abstract Stannin (Snn) was discovered using subtractive hybridization methodology designed to find gene products related to selective organotin toxicity and apoptosis. The cDNAs for Snn were first isolated from brain tissues sensitive to trimethyltin, and were subsequently used to localize, characterize, and identify genomic DNA, and other gene products of Snn. Snn is a highly conserved, 88 amino acid protein found primarily in vertebrates. There is a minor divergence in the C-terminal sequence between amphibians and primates, but a nearly complete conservation of the first 60 residues in all vertebrates sequenced to date. Snn is a membrane-bound protein and is localized, in part, to the mitochondria and other vesicular organelles, suggesting that both localization and conservation are significant for the overall function of the protein. The structure of Snn in a micellar environment and its architecture in lipid bilayers have been determined using a combination of solution and solid-state NMR, respectively. Snn structure comprised a single transmembrane domain (residues 10,33), a 28-residue linker region from residues 34,60 that contains a conserved CXC metal binding motif and a putative 14-3-3, binding region, and a cytoplasmic helix (residues 61,79), which is partially embedded into the membrane. Of primary interest is understanding how this highly-conserved peptide with an interesting structure and cellular localization transmits both normal and potentially toxic signals within the cell. Evidence to date suggests that organotins such as trimethyltin interact with the CXC region of Snn, which is vicinal to the putative 14-3-3 binding site. In vitro transfection analyses and microarray experiments have inferred a possible role of Snn in several key signaling systems, including activation of the p38-ERK cascade, p53-dependent pathways, and 14-3-3, protein-mediated processes. TNF, can induce Snn mRNA expression in endothelial cells in a PKC-, dependent manner. Studies with Snn siRNA suggest that this protein may be involved in growth regulation, since inhibition of Snn expression alone leads to reduced endothelial cells growth and induction of COP-1, a negative regulator of p53 function. A key piece of the puzzle, however, is how and why such a highly-conserved protein, localized to mitochondria, interacts with other regulatory proteins to alter growth and apoptosis. By knowing the structure, location, and possible signaling pathways involved, we propose that Snn constitutes an important sensor of mitochondrial damage, and plays a key role in the mediation of cross-talk between mitochondrial and nuclear compartments in specific cell types. J. Cell. Biochem. 98: 243,250, 2006. © 2006 Wiley-Liss, Inc. [source]