10:00 am - 11:00 am
3-18J Agricultural/Forestry Centre, University of Alberta, Edmonton AB
A graduate exam seminar is a presentation of the student’s final research project for their degree.
This is an ALES MSc Final Exam Seminar by Fatemeh Ashkar. This seminar is open to the general public to attend.
Thesis Topic: The Regulatory Roles of Peptide IRW on Angiotensin-Converting Enzyme 2 (ACE2) in High-Fat Diet-Induced Mice and Spontaneously Hypertensive Rats
MSc with Dr. Jianping Wu.
Metabolic syndrome refers to a cluster of various risk factors commonly associated with cardiovascular diseases (CVDs) and diabetes. Up-regulation of angiotensin-converting enzyme 2 (ACE2), a key member of the renin-angiotensin system (RAS), is generally protective against CVDs and diabetes. IRW, a tripeptide derived from ovotransferrin, was previously studied to reduce blood pressure in spontaneously hypertensive rats (SHRs) via a mechanism of up-regulation of ACE2 in artery. This peptide was also able to improve glucose intolerance in a high-fat diet (HFD)-induced insulin-resistant mouse model, but ACE2 was not affected in the skeletal muscle, the main tissue of glucose metabolism.
Study #1 of the thesis was to investigate the regulatory role of the peptide IRW on aortic ACE2 and its associated signaling pathways in HFD-induced insulin-resistant mice.
In the aorta of HFD mice treated with IRW (at a dose of 45 mg/kg body weight), ACE2 level was significantly increased, while the abundance of angiotensin II receptor (AT1R) and angiotensin-converting enzyme (ACE) was significantly reduced, in comparison to the HFD group. IRW supplementation also improved the abundance of glucose transporter 4 (GLUT4) and the expression of AMP-activated protein kinase (AMPK), Sirtuin 1 (SIRT1), and endothelial nitric oxide (eNOS) in IRW-treated mice. Moreover, IRW down-regulated the inflammatory pathways of endothelin 1 (ET-1) and p38 mitogen-activated protein kinases (P38 MAPK). ACE2 knockdown in vascular smooth muscle cells (VSMCs) reduced the levels of AMPK and eNOS. Our results indicate that the up-regulation of aortic ACE2 by the peptide IRW in HFD-induced insulin-resistant mice is responsible for activating pathways associated with vasodilation of blood vessels, potentially contributing to the improvement of insulin resistance and glucose metabolism.
Study #2 was aimed to understand the regulatory role of peptide IRW on epithelial cadherin (E-cadherin), a transmembrane glycoprotein that enables specific cell-cell adhesion, and its interactions with ACE2. Our previous transcriptome analysis showed that gene expression of E-cadherin was significantly elevated in IRW-treated SHRs. Up-regulation of E-cadherin has been linked to reduced hyperplasia, anti-apoptotic, anti-migratory, and anti-epithelial-mesenchymal transition (EMT) effects in the vasculature. In SHRs, IRW treatment also increased the protein level of E-cadherin, while that of Zinc finger protein SNAI1 (Snail1) was decreased. Similar trend was also observed in VSMCs. Treatment with IRW led to a notable reduction in Orai Calcium Release-Activated Calcium Modulator 1 (Orai1) levels in cells, although no significant change was observed in SHRs. In VSMCs, both angiotensin II (Ang II) stimulation and ACE2 knockdown resulted in a significant decrease in E-cadherin levels. The expression of E-cadherin was significantly increased when VSMCs were treated with either Tamoxifen or IRW. Tamoxifen is commonly utilized for the treatment of breast cancer due to its ability to activate the E-cadherin, thereby causing an increase in the expression of E-cadherin mRNA and protein levels.
Taken together, our studies supported that peptide IRW up-regulates ACE2 in artery to exert its beneficial signaling pathways in both animal models.