Research Abstract |
The unique function of renal glomerulus should be related to its unique structure and molecular components. To understand the structural and functional characteristics of renal glomerulus we first aimed to identify molecules which were specifically present in this structure. We employed differential screening methods to isolate genes which were predominantly expressed in rat glomerulus. Several genes have been isolated as those which were predominantly or uniquely expressed in the glomerulus although their sequences had been registered : olfactomedin-related protein, thymosin β4, heparin-binding epidermal growth factor, VE-cadherin, βCOP and collagen type IV α3 chain. A few novel genes were also isolated as glomerulus-prone ones : 14-1 and 17-3. In addition, several novel genes were identifed as kidney-specific or kidney-prone ones : Ig-Hepta, FR-67 and CS-5. Among them, olfactomedin-related protein and Ig-Hepta were intensively studied. Olfactomedin-related protein was localized in the Golgi apparatus of glomerular podocytes and its C-terminus amino acid sequence, SDEL was a Golgi-retension signal. Ig-Hepta had two Ig-like domains and 7 transmembrane domains. The molecule was immunolocalized in the intercalated cells in the collecting duccts, suggesting a role in acid-base balance regulation.
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