ABSTRACT
Coexpression of constitutively active GSK-3beta[S9A] rescued the axonal pathology induced by overexpression of human tau in transgenic mice (Spittaels et al., (2000) J. Biol. Chem. 275, 41340-41349). We isolated dorsal root ganglion (DRG) neuronal cultures from adult tau4R- and tau4R x GSK-3beta-transgenic mice to define the mechanisms at the cellular and subcellular level. DRG from tau4R-transgenics showed a reduced sprouting capacity while density and stability of microtubules in the axonal processes were significantly increased. Video-enhanced contrast microscopy demonstrated a dramatic inhibition of fast axonal transport. Coexpression of GSK-3beta increased tau phosphorylation and reversed the effects on microtubule stability and saltatory motion. In DRG from GSK-3beta single transgenics, increased tau phosphorylation was evident without any major effects on microtubule stability or axonal transport. These observations support the hypothesis that excess tau competed with motor-proteins for binding to microtubules and/or that a rigid microtubular system inhibits axonal transport.
Subject(s)
Calcium-Calmodulin-Dependent Protein Kinases/genetics , Calcium-Calmodulin-Dependent Protein Kinases/metabolism , Ganglia, Spinal/enzymology , tau Proteins/genetics , tau Proteins/metabolism , Acetylation , Age Factors , Animals , Axonal Transport/physiology , Cells, Cultured , Ganglia, Spinal/pathology , Gene Expression Regulation, Enzymologic , Glycogen Synthase Kinase 3 , Humans , Mice , Mice, Transgenic , Microtubules/chemistry , Microtubules/metabolism , Microtubules/pathology , Neurons/enzymology , Neurons/pathology , Phenotype , Phosphorylation , Tubulin/analysis , Tubulin/metabolism , tau Proteins/analysisABSTRACT
The complexity of the spot patterns of two-dimensional electrophoresis gels made it necessary to use image processing techniques to analyze the gels. An important issue in the analysis is the detection and quantification of the protein spots. In this paper we describe a new technique to segment and model the different spots. For the segmentation of a gel into its different spot regions we apply a watershed technique, which is robust and efficient. For the quantification of the spots, a new spot model is constructed, based on diffusion principles. Besides the advantage of having a physical interpretation, the model is demonstrated to be superior to the commonly used Gaussian models.
