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||Studies on the role of hydrogen peroxide in the myocyte secretion of IGF-1 at developing neuromuscular synapse|
|Date of Defense
||The successful synaptogenesis at neuromuscular junction is an intricate process relies on dynamic interaction of nerve- and muscle-derived molecules. We have previously demonstrated that muscle-derived insulin-like growth factor-1 (IGF-1) facilitate spontaneous neurotransmitter relese and is important in the development of neuromuscular synapse.|
Furthermore, the IGF-1 content in the conditioned medium of Xenopus myocyte culture is significantly increase after hydrogen peroxide (H2O2) application suggesting H2O2 plays an important role in the secretion of IGF-1 from myocyte. Here we dig further to explore the molecular mechanism of H2O2 in myocyte-derived IGF-1 secretion by measure the florescence intensity of DsRed_IGF-1 in cultured Xenopus myocyte. The red fluorescent protein (DsRed) is used as a reporter and DsRed_IGF-1 intensity in a myocyte is monitored by using fluorescence microscope. Bath application of H2O2 significantly attenuates the intensity of DsRed_IGF-1 overexpressed in myocyte.
The H2O2-induced IGF-1 secretion is followed by an increase of cyotosolic calcium while Fluo-4 is used to as a probe. Pretreatment of the culture with Ca2+ chelator BAPTA-AM significantly hampered the H2O2-induced IGF-1 secretion. Moreover, exclusion of Ca2+ from culture medium abolished the H2O2-induced IGF-1 secretion, suggesting Ca2+ influx play a crucial role in this process. Bath application of ryanodine receptor inhibitors either antagonist 8-(dethylamino) octyl 3, 4, 5-trimethoxybenzoate (TMB-8) or Ruthenium red significantly occluded H2O2-induced IGF-1 secretion.
Overall, results from our current studies have shed some lights on signaling mechanism underlying the H2O2-induced secretion of IGF-1 from myocyte in the early development of neuromuscular synapse.
||Chang-Yi, Wu - chair|
Bin-Nan Wu - co-chair
Jau-Cheng Liou - advisor
Indicate in-campus at 2 year and off-campus access at 2 year.|
|Date of Submission