| Background: Gene GDDR(Gastric Drastic Down-Related gene)which encodes a putative 184 amino acid protein was initially found and cloned in vitro by our research team. Our previous research showed that GDDR was speciafically and highly expressed in the pit cells in the gastric mucosa. Trefoil factor family(TFF) proteins synthesised and secreted by gastric mucosal cells exist largely in gastric mucosa. TFF1 and TFF2 are the main member of trefoil factor family. They play an important role in gastric mucosal protection and repair through mediating mucins, gastric acid, the cell-cell adherence, migration, proliferation and apoptosis. Research showed that GDDR can interact specially with TFF1 in vivo as a heterodimer which is expressed specially in gastric epithelium and play an important role in mucosal protection. Therefore,we hypothesis that GDDR may be vital to mucosa and this function might relate to TFF1. This study explores elementarily the role of GDDR played in acute and chronic gastric injury.Aims: 1. To identify comprehensively gene GDDR knock out mice. 2. To establish mouse model of acute gastric injury in order to explore the role of GDDR in acute gastric mucosal injury. 3. To conduct a preliminary study of the mechanisms of GDDR involved in acute gastric mucosal injury in mice. 4. To establish mouse model of chronic gastric lesions in order to study the role of GDDR in chronic mucosal injury.Methods: 1. GDDR gene knock out mice were identified comprehensively through the genomic DNA level, m RNA transcription level, protein expression and tissue location level. 2. The mouse model of acute gastric injury was established by means of water-immersion restraint stress in GDDR-/- and GDDR+/+ mice. Gastric mucosal lessions, HE staining and electron microscopy were used to value gastric mucosa injury. The number and the activity of neutrophils in blood and in gastric tissues were detected to analyze the role of GDDR played in acute gastric injury. 3. Real-time PCR was used to screen inflammation-related and gastric mucosal protection related molecules.Then the obtained molecules were verified by ELISA and immunohistochemistry.Western blot was applied to conduct a preliminary investigation of the signaling pathways involved in the acute gastric mucosal injury of GDDR-/- and GDDR+/+ mice.Then the relevant signaling pathway inhibitors was used to verify the role of relevant signaling pathways in the acute gastric lesions in mice. 4. The mouse model of chronic gastric mucosal injury was established by using HP infecting GDDR-/- and GDDR+/+ mice. Gastric mucosal lessions and HE staining were used to observe stomach injury to explore preliminarily the role GDDR played in chronic stomach injury.Results: 1. There is no GDDR expression in GDDR knock out mice fron genomic DNA level, m RNA transcription to protein expression and tissue location level. But the expression of GDDR is nomal in the corresponding GDDR+/+ mice. 2. The degree of acute gastric mucosal injury in GDDR+/+ mice was more serious than that in GDDR-/-. And neutrophil count in blood and MPO activities in gastric tissue in GDDR+/+ mice were higher than that in GDDR-/- mice. 3. Real-time quantitative PCR showed the expression of inflammatory molecules IL-6 and chemokines CXCL2 in the gastric tissue of GDDR+/+ mice were significantly higher than that in GDDR-/- mice.ELISA and immunohistochemistry results are in consistent with the above results.Western blot suggested the expression of phosphorylated stat3 in acute gastric injury in GDDR+/+ mice was significantly stronger than that in GDDR-/- mice. 4. The results of gastric mucosal lessions and HE staining show that the degree of chronic gastric injury in GDDR-/- mice were more serious than that in GDDR+/+ group.Conclusions: 1. GDDR knock out mice were successfully contruced. 2. The new gene GDDR may contribute to acute stress-induced gastric mucosal injury in mice may through promoting the expression of CXCL2 and IL-6 and activating STAT3 signaling pathway. 3. The new gene GDDR may play an role of protecting chronic gastric mucosal injury induced by Hp infection in mice and the relevant mechanism are needed for further study. |
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