The Expression Of BMP-2,6,7 And TC10 In The Facial Nerve Motoneurons During The Regeneration Of Rats' Facial Nerve Injury

The Expression of BMP-2,6,7 and TC10 in the Facial Nerve Motoneurons during the Regeneration of Rats' Facial Nerve InjuryThe Bone Morphogenetic Proteins (BMPs) family of secreted signaling molecules belongs to the transforming growth factor beta superfamily. The initail discovery of BMPs was made based on the abiliity of purified bone extracts to promote ectopic cartilage and bone formation when implanted under the skin or into the moscle of adult rats. However, it is now evident that the BMP family consists of a large number of genetically related molecules. Conserved in evolution, with key role in different periods of central nervous system. Rho families have been implicated in the regulation of cytoskeleton, until recently, some member of this family could promote the hypoglossus. No reports show whether BMPs and TC10 play important role in facial nerve injury. Therefore, our experiments have investigated the expressions of endogenous BMPs and TC10 in the facial motoneuron and their roles.1. The experiment study about the changings and roles ofBMP-2,6,7 after facial nerve axtomy.Previous studies were focused in the effects of BMPs on central nervous system. But to peripheral nerve, there were only localized in neuron culture Relevant information about the changing of BMP-2,6,7 after facial nerve transection were't found. We set up the facial nerve crush injury model in rat to examine these indexes. The result verified that the expression of BMP-2 decrease after injury. Postoperative 2 week, BMP-2 resumes to normal. BMP-6,7 increase gradually after axtomy, and reach maximum at 7 days post injury; then, BMP-6 resumed to normal level on postoperative 4 week. But BMP-7 was still expressed abundantly in the facial motoneurons. These results reveal that some member of BMPs family such as BMP-2,6,7 might be facial nerve potential neurotrophic factors through the change of expression to trigger facial nerve regeneration. The BMP-6 implicates in maintenance of nerve regeneration.2. The experiment study about the changings and roles of BMPR- I and after downstream signal molecule Smad 1 facial nerve axtomy.BMPs exert their biological effects through two types of transmembranereceptors BMPR- I and BMPR- II ,which possess intrinsic serine/threonine kinase activity, and through downstream molecule Smadl transfer signal into the cytoplasm. We identified the expressions of BMPR- I and Smadl in facial nerve axtomy. The results show the upregulation of BMPR-1 and Smadl after injury. The peak value was sustained to 4w group. The result specified that BMPR- I and Smadl have implicated in the processes of the effects of BMP-2,6,7 on nerve regeneration.3. The effect and expression of small GTP binding protein TClOmRNA on the facial motoneuron regenerationTC10 belongs to the family of small GTP-binding proteins. Its functions and actions are similar to RhoA. Racl and Cdc42. The alternation between GTP-bound and GDP-bound form is thought to act as bimodal switches, and regulate many intracellular sighalling pathways. Early studies with small GTP-binding proteins play major roles in regulating remodelling of the actin cytoskeleton induced by exteacellular signals. We investigate the change of GTP binding protein TC10 in the facial motoneuron regeneration. The TC10 cDNA probe was derived from facial nucleus by RT-PCR technology. The different expressions of TC10 mRNA are observed by in situ hybridization on normal and regenertional facial motoneurons. In the normal group, the expression of TCI0 is low. The amount of the TC10 mRNA increases gradually from 1-day group following facial nerve injury. At 1-month group, it reaches maximum. TC10 may act an important role in signal transduce and cytoskeleton remodeling after nerve axotomy. Moreover, it could promote the nerve axon growth.