Date of Award

2019

Document Type

Campus Access Master's Thesis

Degree Name

Master of Science in Biological Sciences (MS)

Administrative Home Department

Department of Biological Sciences

Advisor 1

Zhiying Shan

Committee Member 1

Qing-Hui Chen

Committee Member 2

Xiaoqing Tang

Abstract

Orexin A is a multifunctional neuropeptide that regulates arousal, wakefulness, appetite and cardiovascular function. Orexin A exists its function through binding with orexin receptor 1 (OX1R) or orexin receptor 2 (OX2R). However, the downstream signal transduction pathway that mediates orexin system function is not well determined. In this study, we investigated the hypothesis that binding of orexin A and OX1R results in activation of extracellular signal-regulated kinase 1 & 2 (ERK1/2) , which in turn active AP1 transcription factor, the AP1 stimulates expression of Proinflammatory cytokines. We test this hypothesis using the neuron- like PC12 cell which artificially expressing human OX1R (PC12-OX1R). Incubation of human orexin A (100 nM) resulted in a time dependent increase in phosphorylated ERK1/2 (P-ERK1/2) as well as the mRNA levels of Junb, a subunit of transcription factor AP-1; leukemia inhibitory factor (LIF), and C-C motif chemokine ligand 2 (CCL2), in PC12-OX1R cells. The maximum increase in Junb was observed in 3 hours, while the maximum increase in LIF (18.3-fold) and CCL2 (12.8-fold) was observed 6 hours following orexin A treatment. There were no significant increases in P-ERK1/2, Junb, CCL2 and LIF in orexin A treated PC12- OX2R cells or PC12 cells. Pre-incubation of PC12-OX1R cells with PD98059, a blocker for ERK1/2 phosphorylation, dramatically attenuated the expression of Junb, LIF and CCL2 induced by orexin A. Pre-incubation of PC12-OX1R cells with curcumin (20 μM) blocked increases in CCL2 and LIF induced by orexin A. Our results suggested that activation of orexin system activity stimulates ERK1/2 - AP1-cytokine signaling.

Available for download on Thursday, June 18, 2020

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