Papers by Keyword: Nerve Growth Factor

Abstract: Currently, most commercialized peripheral nerve regenerative products are constructed from biodegradable polymers into hollow conduits. To speed up the regeneration rate, we proposed a development of a biocompatible protein-filled conduit for anastomosis amputated peripheral nerve with growth factor controlled release function. Glutaraldehyde-crosslinked protein sponges were tested for their abilities to controlled release of nerve growth factor (NGF) in vitro in our previous experiments. Type B gelatin sponges were able to limit diffusions of NGF due to electrostatic interactions between them. The rate of growth factor releases would be depended on degradation of the crosslinked gelatin. A nerve conduit model was produced using perfluoro alkoxy (PFA) tubes filled with gelatin which had been crosslinked using X-ray from Argon plasma treatment. This method of crosslinking provided 21.22±3.03 % degree of crosslinking. Hollow nerve conduits fabricated from poly(l-lactide-co-caprolactone) (PLCL) had a thicknesses and an inner diameters of 0.31±0.03 mm and 1.63±0.07 mm respectively. Average pore sizes of the inner surfaces and outer surfaces were 9.70±3.44 µm and 1.24±0.77 µm respectively. PLCL film supported growth of L929 mouse fibroblasts. For continuing works, we are testing the protein-filled conduits for peripheral nerve regeneration in animals.

Abstract: Extracellular signal-regulated kinases (ERKs) are phosphorylated on threonine and tyrosine residues at 183 and 185, respectively, and then translocated from cytosol to nucleus. ERK2 is retained in the nucleus for several hours by nerve growth factor (NGF), and this sustained retention of ERK2 in the nucleus has effect on the fate of biological response toward differentiation by neurite outgrowth in PC12 cells. The overexpression of Green Fluorescent Protein (GFP)-ERK2 and mutated GFP-ERK2 constructs without anchoring protein MEK1 were distributed throughout the resting and the activated cells. When GFP-ERK2 coexpressed along with MEK1, cytosolic localization of GFP-ERK2 is retained by MEK1 in the resting PC12 cells. This cytosolic retention was due to the binding of ERK2 to the MEK1. Upon stimulation by growth factors, the association between GFP-ERK2 and MEK1 was detached from each other, and then GFP-ERK2 was translocated into the nucleus. However, inactive form of the MKP-3 cytosolic phosphatase forced ERK cytosolic retention in PC12 cells were either left untreated or stimulated by NGF. When the transfected PC12 cells were treated for 72hrs with NGF, GFP-ERK2 was distributed the cytosol. Regarding its subcellular localization, the roles of residues 179-185 located in the activation loop of ERK2 were examined. The substitution of residues in the activation loop to alanine showed different localization on the nuclear translocation of ERK2 in PC12 cells.