What do you think?
Rate this book
Studies of Heparanase (HPA) Gene Expression, Cellular Localization and Functions in Neural Tissues of the Rat
This dissertation, "Studies of Heparanase (HPA) Gene Expression, Cellular Localization and Functions in Neural Tissues of the Rat" by Yi, Zhang, 張怡, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author.
Abstract of thesis entitled "Studies of heparanase (HPA) gene expression, cellular localization and functions in neural tissues of the rat" Submitted by Zhang Yi
for the degree of Doctor of Philosophy at The University of Hong Kong in 2007
Heparan sulfate proteoglycans (HSPGs) bound with growth-associated molecules and neurotrophic factors are considered important to axonal growth and navigation in development. Increases in soluble forms of HS after crush injury and upregulated regeneration following supplementation of soluble HSs in a nerve bridge model suggest the requirement for HS mobilization in axonal regrowth and regeneration after injury. We hypothesized the involvement of heparanase, a mammalian HS-cleaving endoglycosidase, for HS mobilization to assist in axonal growth during development and post-traumatic regeneration.
Heparanase expression in the spinal cord of normal adult rat provided the reference for comparison. RT-PCR indicated the heparanase mRNA expression. In situ hybridization for the mRNA revealed expression in neurons and white matter glia. Immunohistochemistry further showed cytoplasmic localization of the heparanase protein. Double immunofluorescence for heparanase and syndecan-3 revealed colocalization of the proteins in cell bodies of neurons and oligodendrocytes, suggesting constitutive expression in these cell types. In contrast, only subpopulations of astrocytes and NG2-expressing glia in the white matter expressed heparanase and these did not show co-expression of syndecan-3.
Change of heparanase expression with hemisection of the spinal cord was then studied. Quantitative PCR and in situ hybridization (ISH) for the heparanase transcript in cord tissue peripheral to the lesion at T8 indicated decreased expression I in 3 days post-injury (DPI) and subsequent increase to levels in excess of that in the normal cord in 7 and 14 DPI. ISH for heparanase mRNA in combination with immunostaining for cell markers indicated no change in expression pattern among neurons and glia in regions beyond the lesion-surround at all time points tested. However, in the lesion-surround at 3 DPI, heparanase expression was barely detectable; by 7-14 DPI, heparanase expression was identifiable in reactive astrocytes and macrophages but not in oligodendrocytes that lost association with axons. Cultures of astrocytes further evidenced upregulation of heparanase expression with TGF-b1 treatment but no accompanying upregulation of syndecan-3. Increased expression of heparanase in migratory astrocytes in the scratch-wound model also simulated the response of astrocytes in spinal cord injury.
To further demonstrate a role of heparanase in migratory cells of neural tissue, dorsal root ganglion (DRG; E15 rat) explant cultures were used. ISH located heparanase mRNA in neurons and Schwann cells that emigrated away from the explant tissue. Cells that remained within the explant center were low in the heparanase message. These results were reinforced by heparanase immunoreactivity in cells assessed for motility by time-lapse video microscopy. qPCR of growing axons prepared from either Campenot chambers or filter inserts however revealed no detectable heparanase transcript. Together with the significantly higher heparanase activity in 2-day cultures than in neat explants, the results provide evidence for heparanase involvement in neu
Abstract of thesis entitled "Studies of heparanase (HPA) gene expression, cellular localization and functions in neural tissues of the rat" Submitted by Zhang Yi
for the degree of Doctor of Philosophy at The University of Hong Kong in 2007
Heparan sulfate proteoglycans (HSPGs) bound with growth-associated molecules and neurotrophic factors are considered important to axonal growth and navigation in development. Increases in soluble forms of HS after crush injury and upregulated regeneration following supplementation of soluble HSs in a nerve bridge model suggest the requirement for HS mobilization in axonal regrowth and regeneration after injury. We hypothesized the involvement of heparanase, a mammalian HS-cleaving endoglycosidase, for HS mobilization to assist in axonal growth during development and post-traumatic regeneration.
Heparanase expression in the spinal cord of normal adult rat provided the reference for comparison. RT-PCR indicated the heparanase mRNA expression. In situ hybridization for the mRNA revealed expression in neurons and white matter glia. Immunohistochemistry further showed cytoplasmic localization of the heparanase protein. Double immunofluorescence for heparanase and syndecan-3 revealed colocalization of the proteins in cell bodies of neurons and oligodendrocytes, suggesting constitutive expression in these cell types. In contrast, only subpopulations of astrocytes and NG2-expressing glia in the white matter expressed heparanase and these did not show co-expression of syndecan-3.
Change of heparanase expression with hemisection of the spinal cord was then studied. Quantitative PCR and in situ hybridization (ISH) for the heparanase transcript in cord tissue peripheral to the lesion at T8 indicated decreased expression I in 3 days post-injury (DPI) and subsequent increase to levels in excess of that in the normal cord in 7 and 14 DPI. ISH for heparanase mRNA in combination with immunostaining for cell markers indicated no change in expression pattern among neurons and glia in regions beyond the lesion-surround at all time points tested. However, in the lesion-surround at 3 DPI, heparanase expression was barely detectable; by 7-14 DPI, heparanase expression was identifiable in reactive astrocytes and macrophages but not in oligodendrocytes that lost association with axons. Cultures of astrocytes further evidenced upregulation of heparanase expression with TGF-b1 treatment but no accompanying upregulation of syndecan-3. Increased expression of heparanase in migratory astrocytes in the scratch-wound model also simulated the response of astrocytes in spinal cord injury.
To further demonstrate a role of heparanase in migratory cells of neural tissue, dorsal root ganglion (DRG; E15 rat) explant cultures were used. ISH located heparanase mRNA in neurons and Schwann cells that emigrated away from the explant tissue. Cells that remained within the explant center were low in the heparanase message. These results were reinforced by heparanase immunoreactivity in cells assessed for motility by time-lapse video microscopy. qPCR of growing axons prepared from either Campenot chambers or filter inserts however revealed no detectable heparanase transcript. Together with the significantly higher heparanase activity in 2-day cultures than in neat explants, the results provide evidence for heparanase involvement in neu
Paperback
Published January 27, 2017
Ratings & Reviews
Friends & Following
Create a free account to discover what your friends think of this book!
Community Reviews
No one has reviewed this book yet.