epidermal-growth-factor and Hypothermia

The transformation of rat primary glial cells into mesenchymal stem cells (MSCs) is intriguing as more seed cells can be harvested. The present study aimed to evaluate the effects of growth factors, hypoxia and mild hypothermia on the transformation of primary glial cells into MSCs. Rat primary glial cells were induced to differentiate by treatment with hypoxia, mild hypothermia and basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF). Immunohistochemistry and western blotting were then used to determine the expression levels of glial fibrillary acidic protein (GFAP), nestin, musashi‑1, neuron specific enolase (NSE) and neuronal nuclei (NeuN), in each treatment group. bFGF and EGF increased the proportion of CD44

Topics: Animals; Antigens, Differentiation; Cell Differentiation; Cell Hypoxia; Epidermal Growth Factor; Female; Fibroblast Growth Factor 2; Hypothermia; Male; Mesenchymal Stem Cells; Neuroglia; Rats; Rats, Sprague-Dawley

The small GTPase Ras is converted to the active, GTP-bound state during exposure of vertebrate cells to hypothermic stress. This activation occurs more rapidly than can be accounted for by spontaneous nucleotide exchange. Ras-guanyl nucleotide exchange factors and Ras GTPase-activating proteins have significant activity at 0 degrees C in vitro, leading to the hypothesis that normal Ras regulators influence the relative amounts of Ras-GTP and Ras-GDP at low temperatures in vivo. When hypothermic cells are warmed to 37 degrees C, the Raf-Mek-Erk protein kinase cascade is activated. After prolonged hypothermic stress, followed by warming to physiologic temperature, cultured fibroblasts assume a rounded morphology, detach from the substratum, and die. All of these biologic responses are attenuated by pharmacologic inhibition of Mek. Previously, it had been found that low temperature blocks acute growth factor signaling to Erk. In the present study, we found that this block occurs at the level of Raf activation. Temperature regulation of Ras signaling could help animal cells respond appropriately to hypothermic stress, and Ras-Erk signaling can be manipulated to improve the survival of cells in cold storage.

Topics: Animals; Calcium-Calmodulin-Dependent Protein Kinases; Cell Line; Cell Survival; Dogs; Enzyme Activation; Enzyme Inhibitors; Epidermal Growth Factor; Fibroblasts; Guanosine Triphosphate; Humans; Hydrolysis; Hypothermia; ras Proteins; Rats; Signal Transduction