PS-B01-5: TISSUE-SPECIFIC REGULATION OF LRG1 EXPRESSION IN MULTIPLE HYPERTENSION MODELS OF MOUSE

Abstract

Object: Leucine-rich alpha-2-glycoprotein-1 (LRG1), which is firstly isolated from human plasma, has been reported to be related to several diseases as a biomarker or a pathogenic factor. Serum LRG1 is associated with the prognosis of diabetic nephropathy and cardiovascular diseases, and we previously demonstrated that LRG1 especially plays a pivotal role in the initial development of diabetic nephropathy. In addition, a previous study showed that increased plasma LRG1 levels in patients with type 2 diabetes mellitus was associated with increased systolic blood pressure (BP), arterial stiffness estimated by pulse wave velocity, and decreased endothelium-dependent vasodilation estimated by laser doppler flowmetry. However, the relationship between LRG1 and BP have remained substantially unknown. With respect to the function of LRG1, LRG1 is expressed in endothelial cells and promotes pathological angiogenesis by modulating TGF-beta signaling. LRG1 switches TGF-beta signaling from the Smad2/3 pathway to the Smad1/5/8 pathway. In addition, the activation of Smad2/3 signaling enhanced endothelial nitric oxide synthase (eNOS) production and promoted endothelium-dependent vasodilation. Suppressing eNOS activity reduces NO levels and leads to endothelial dysfunction and hypertension. Moreover, LRG1 is increased in response to inflammation and oxidative stress in endothelial cells. However, little is known about the relationship between LRG1 in endothelial cells and eNOS. Based on the previous findings, we hypothesized that LRG1 may inhibit eNOS production by potentially blocking the Smad2/3 pathway, which will promote to form a vicious cycle that progresses vascular endothelial damage and hypertension. As the first step to elucidate this hypothesis, we investigated LRG1 expression in various tissues including vascular endothelium in some hypertension models with endothelial dysfunction. Design and method: Male 10–12 weeks-aged C57/BL mice were divided into control and hypertension with endothelial dysfunction. BP was measured using a tail-cuff method during the experiment, and mice were sacrificed and their organs were collected at the end of the experiment. We examined the expression of LRG1, Smad2/3, Smad1/5/8 and NOS in the vascular endothelium, kidney, heart, adipose tissue by PCR, Western blot and immunohistochemical analyses. Results: We are currently conducting the experiments and will present our findings at this conference. Conclusion: We plan to present the results of tissue-specific regulation of LRG1 expression in some hypertension models of mice at this conference.