Fyn Tyrosine Kinase-mediated Tyrosine Phosphorylation of Roundabout (Robo), the Slit Receptor / 대한해부학회지

In this study, the molecular mechanism of tyrosine phosphorylation of Roundabout (Robo), the transmembrane receptor for slits, was investigated. The tyrosine phosphorylation of intracellular portion of Robo was increased by the treatment of tyrosine phosphatase inhibitors in human embryonic kidney cells transfected with Robo. The Robo tyrosine phosphorylation was inhibited by the treatment of Src family kinase inhibitor, PP2. The co-transfection of constitutively active form of Fyn, not the dominant negative form of Fyn, and Robo dramatically enhanced the tyrosine phosphorylation of Robo. Furthermore, the SH2 domain of Fyn, which binds to phosphorylated tyrosine residues, interact with Robo, and the interaction was increased by the inhibition of tyrosine phosphatases. These findings indicate that the tyrosine phosphorylation of Robo is regulated by Fyn.

Signal Transduction of Ras-like GTPase Activation in the Nervous System / 대한해부학회지

Synaptic plasticity has been thought to be a mechanism of synaptic maturation, learning and memory. In this study, the possible involvement of Rac, RhoA, proline-rich tyrosine kinase 2 (PYK2) and focal adhesion kinase (FAK) in the synaptic plasticity was investigated using PC12 cells and rat brains. The followings are the results. 1. Depolarization induced extracellular signal-regulated kinase (ERK) activation but did not activate Rac and RhoA in PC12 cells. 2. ERK activation and c-fos expression were observed after electroconvulsive shock (ECS) but the activity of Rac and RhoA was not changed following ECS. 3. PYK2 not FAK activation was observed after ECS. 4. The activity of PYK2 was increased with postnatal development but that of FAK was decreased with ages. 5. The expression of Rac and PYK2 was clearly observed in the postsynaptic density but that of RhoA and FAK was not. These findings indicate that PYK2 seems to play an important role in activity-dependent synaptic plasticity in vivo brain.

Immunohistochemical Reaction of Calcitonin-gene-related Peptide and Type II Collagen and Morphological Changes of Cartilage Implants and Cultured Chondrocytes / 대한해부학회지

The purpose of this study was to investigate the immunohistochemical reaction of calcitonin-gene-related peptide (CGRP) and type II collagen and also morphological changes of cartilage implants and cultured chondrocytes isolated from the articular and costal cartilages. The chondrocytes were isolated from the head of the femur and the 11th costal cartilage of the 6 months old rabbits. De novo implants were prepared from the chondrocytes cultured on the perichondrium by culturing isolated articular chondrocytes. Cultured chondrocytes and implants were evaluated by immunohistochemical staining of CGRP and type II collagen and electron microscopy. Articular chondrocytes maintained the typical phenotype in the 1st and 2nd subcultures, but the costal chondrocytes were transformed into fibroblast-like cells. The articular chondrocytes cultured on the perichondrium were more flattened and formed the cartilage. Most chondrocytes were no loss of type II collagen immunostaining by culturing. Implants replaced by the cultured articular chondrocytes were generally increased CGRP and decreased type II collagen immunoreaction. Electron microscopically the cultured articular chondrocytes had a large euchromatic nucleus, a few granules, and abundant vesicles. During culture, the nucleus became atropy and the cytoplasm contained many large vacuoles. The chondrocytes cultured on the perichondrium showed a lot of segmented rough endoplasmic reticulum and fine short microvilli. During culture, articular chondrocytes maintained typical phenotype and type II collagen reaction. The cultured articular chondrocytes had some organelles and euchromatic nucleus with prominent nucleolus. The chondrocytes cultured on the perichondrium showed active secretion of the matrix with small vesicles and well developed endoplasmic reticulum. The implanted articular chondrocytes showed the decrease of their organelles after secretion of the marix and became increased CGRP and decreased type II collagen immunoreaction.

A study on the expression of immediate-early genes by light stimuli in the rat suprachiasmatic nucleus using differential display / 대한해부학회지

The hypothalamic suprachiasmatic nucleus (SCN) of the mammal is the circadian pacemaker responsible for generation of circadian rhythms. Several immediate-early genes are expressed in the SCN by light stimuli which induce phase shifts of animal activity rhythms. By using differential display-polymerase chain reaction, we investigated expression of several immediate-early genes in the light-stimulated SCN. In addition, we analyzed the light-induced expression changes of two known immediate-early genes, Arc and Rheb, in the SCN. We have screened and cloned 25 differentially expressed genes in the SCN, and identified a gene, a rat homologue of A6 kinase, which expression was regulated by light stimuli. One hour light stimuli during the subjective night dramatically induced the gene expression in the SCN, whereas light stimuli during the subjective light phase did not. This finding implies that a rat homolgue of A6 kinase may be involved in the photic entrainment of the circadian clock. On the other hand, Arc and Rheb mRNA expressions were not increased in the SCN by light stimuli.

Morphometrical and Histological Changes of Glomeruli and Proximal tubules of Contralateral Kidney in Uninephrectomized Rat / 체질인류학회지

This study was to investigate the histomorphomeric and histological changes of glomeruli and proximal tubules of contralateral kidney in uninephrectomized rat. Rats were Sprague Dawley strain and female 1-year-old. Uninephrectomized rats were sacrificed after 20 days, 30 days, and 40 days. The results were as follows: 1. The mean areas and diameters of the glomeruli were markedly increased at the 30 days. 2. In the glomeruli, the mean nuclear areas of podocytes were markedly increased, but those of cells of the parietal layer were decreased. At the 20 days, those of the endothelial cells were slightly incerased. 3. The lumens of the endothelial cells were irregularly expanded and folded at the 20 days. The basal lamina of the 30 days was markedly thickened in the electron microscopic finding. 4. At the 30 days, the mean areas and mean thicknesses of proximal tubules were markedly increased, but those were not normal. At the 40 days, the mean thicknesses of proximal tubules were restored to the almost normal. 5. Light microscopic changes of the proximal tubules had no difference between the control and the experimental group. In electron microscopical findings, the cytoplasm of the proximal tubules were densely filled with the enlarged mitochondria at the 30 days. At the 40 days, some large vacuoles appeared in the cytoplasm.

Structural Changes of the Nucleus Pulposus Cells and Cartilage Cells of Age-Related Intervertebral Disc in Mongrel Dog / 대한해부학회지

The intervertebral discs of the dog from the newborn, the 1 year old, and the 5 years old were examined about the cell morphologies and their structural changes according to the advancement of age by histomorphometry and electron microscopy. The three regions of the disc - the nucleus pulposus, the inner and outer annulus fibrosus were considered. Each region was divided into the three zones - the peripheral, intermediate, and central zones. The cell morphology of the three regions were as follows : A. The nucleus pulposus 1. At the newborn, the cells of the nucleus pulposus had long cytoplasmic processes forming large extracellular vacuoles. In the peripheral and intermediate zones, the cells with euchromatic nucleus had fine cytoplasmic granule-like fibers and some of free ribosomes. In the central zone, the cells with heterochromatic nucleus had many cytoplasmic vacuoles filled with free ribosomes. 2. At the 1 years old, the cell-group composed of 4 to 8 cells contacted each other with their cytoplasmic processes. In the peripheral zone, the elliptical chondroblast-like cells with euchromatic nucleus had well-developed rough endoplasmic reticulum and mitochondria. In the intermediate zone, the foam-like large round cells with euchromaic nucleus had multiple cytoplasmic vacuoles filled with granular contents. In the central zone, the cells with heterochromatic nucleus had large cytoplasmic vacuoles, and seemed to be degenerated type of the outer zone-cells. 3. At the 5 years old, the cells in the periphery were rhomboid or polygonal with euchromatic nucleus, and had broad cytoplasmic contact surface with adjacent cells. They had small cytoplasmic vacuoles, well-developed Golgi apparatus and rough endoplasmic reticulum. The cells in the intermediate zone had heterochromatic nucleus and a lot of variable size of cytoplasmic vacuoles, and seemed to be degenerated form of the cells of the periphery. In the central zone, the star-like cells with heterochromatic nucleus had multiple sharp cytoplasmic processes and vacant cytoplasm because of large cytoplasmic vacuoles. B. The cartilaginous part and the inner annulus fibrosus 1. At the newborn, the outer zone of the cartilaginous part of the intervertebral disc showed the isogenous group with 2 to 3 chondrocytes within the cell nest. The cells were distributed mainly around the blood vessels, and had euchromatic nucleus. They had small cytoplasmic vacuoles, well-developed rough endoplasmic reticulum and abundant ribosomes. The cells of the inner zone showed heterochromatic nucleus, well-developed rough endoplasmic reticulum and expanding terminal cisternae. 2. At the 1 year old, the inner annulus fibrosus was divided into the fibrocartilaginous part and the hyaline cartilaginous part. The former, the outer zone showed the cell nest with 2 to 4 of elliptical chondrocytes which had euchromatic nucleus, small cytoplasmic vacuoles and scattered fine granules. The latter, the inner zone showed the chondrocytes within the dissociated cell nest with heterochromatic nucleus. They had disperse rough endoplasmic reticulum and microvilli-like cytoplasmic processes. 3. At the 5 years old, the annulus fibrosus was composed mainly of fibrocartilage. The chondrocyte showed heterochromatic nucleus, long cytoplasmic processes, large cytoplasmic vacuoles and densely packed abundant granules. C. The outer annulus fibrosus 1. At the 1 year old, the outer annulus fibrosus was composed of the palisading collagenous bundles. The chondrocytes with heterochromatic nucleus located in the cartilage cell nest. The cells had well-developed rough endoplasmic reticulum, mitochondria, and Golgi apparatus, and 4 to 5 processes of interterritorial matrix surrounded the collagenous bundles. 2. At the 5 years old, the collagenous bundles were invaded by the processes of interterritorial matrix, and made them incomplete ones. The cell had heterochromatic nucleus and scanty cytoplasm containing small mitochondria and poorly developed organelles. The Summary of The Above Mentioned Findings Are : 1. The cells of the nucleus pulposus were degenerated gradually from the periphery toward the center. 2. The cells of the nucleus pulposus were degenerated gradually according to the aging process. 3. With age, the cells of the annulus fibrosus were degenerated, the hyaline cartilage was replaced gradually by fibrocartilages, and fragmentation of the collagenous bundles appeared. 4. The older the age, the smaller the nucleus of the nucleus pulposus cells, and the larger the nucleus of the annulus fibrosus cells were encountered in the histomorphometric measurement.

Ultrastructural heterogeneity in the dynamic organ cultured liver cells of postnatal and adult rats / 대한해부학회지

No abstract available.