Expression of mRNA encoding the related extracellular matrix glycoproteins, SC1 and SPARC, in the developing and adult rat central nervous system
Year: 2002
Type: dissertation
Abstract: SC1 and SPARC are matricellular glycoproteins which possess anti-adhesive and calcium-binding properties and play regulatory roles in modulating cellular interactions. In the rat embryo, SC1 mRNA was strongly expressed in the embryonic brain and spinal cord, whereas SPARC mRNA was enriched in craniofacial cartilage and skeletal structures. This differential expression pattern suggests that SC1 plays an important role in the developing nervous system, whereas SPARC participates primarily in events associated with skeletal development. However, these ECM molecules show parallel expression patterns in areas of the developing cerebellum undergoing cell migratory events. In the developing cochlea of the inner ear, SC1 mRNA was highly expressed in neurons of the spiral ganglion, whereas SPARC transcripts were enriched in the temporal bone and cartilaginous otic capsule surrounding the cochlea. Both SC1 and SPARC mRNA were expressed in connective tissue elements involved in maintaining ionic homeostasis of cochlear fluids. Concomitant with the onset of hearing, SPARC was induced in Deiters cells of the organ of Corti. This suggests that SPARC may be involved in calcium regulation when functional maturation of the cochlea is attained and rapid changes in calcium levels are required. Examination of the intracellular localization of SC1 transcripts in neural cells in vivo revealed that SC1 mRNA was selectively transported into processes of Bergmann glial cells in the cerebellum at specific stages during development and in the adult. The localization of SC1 mRNA to processes of these glial cells in the synaptic-rich molecular layer of the cerebellum could facilitate local control of SC1 protein synthesis which may play roles in synapse formation during development and in synaptic plasticity in the adult. Furthermore, transport of SC1 mRNA into Bergmann glial cell processes was transiently diminished after whole-body hyperthermia. However, hyperthermia did not appear to affect the morphology of intermediate filaments or the ?-tubulin component of microtubules in processes of Bergmann glial cells in vivo. In summary, these findings suggest that SC1 and SPARC share both overlapping and distinct functions, and may play a role in cell migration and differentiation during development, and in synaptic plasticity in the adult central nervous system.
Source: TSpace (University of Toronto)
Author: Mothe, Andrea Jean
Institution: University of Toronto
Language: English
Subfield: Rheumatology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7133098451