探討RRBP1基因對於心血管疾病與壓力反應所扮演之角色

Abstract

簡介：去年發表的文章中，有團隊指出在擴張型以及缺血型心臟疾病中，皆會高度表達核醣體結合蛋白（RRBP1）。而先前於本實驗室中，也有發現核醣體結合蛋白缺失可能會增加一氧化氮合成酶（NOS）導致胞內鈣離子失恆。 目的：探討在心血管疾病中RRBP1表達量的變化，以及釐清細胞在壓力環境下所產生的壓力反應與RRBP1之間的關聯性。 材料與方法：本篇使用C57BL/6鼠，以化學藥品誘導產生心衰竭、高血壓等疾病模式，藉此了解疾病狀態下RRBP1的表達。也使用rrbp1-/-鼠（KO），以心導管技術做為心臟功能之測試。另外使用人類內皮細胞（HUVEC）、人類胚胎腎細胞（HEK293T）以及老鼠心房細胞（HL-1）作為物種間差異的研究，並給予壓力環境或是誘導、抑制其RRBP1的製造，藉此測試RRBP1、一氧化氮合成酶 (NOS)與細胞存活率之間的關聯性。 實驗結果：我們觀察到，在不同病理損傷的程度下，老鼠心臟的rrbp1表達也會隨之改變。施打乙型交感神經作用劑isoproterenol後，在劑量較低的情況下，老鼠心臟所受的損傷較輕微，此時的rrbp1隨著損傷程度而呈現正向增加。若是在高劑量下，老鼠心臟受到嚴重損傷，則rrbp1表現量並不會隨之提升。而在人類細胞中，使之過度表達RRBP1可增加內皮性一氧化氮合成酶（eNOS）的表現，但增加RRBP1表達並不能在缺氧/再灌流的壓力環境下保護細胞的存活。在老鼠高血壓的模式中，給予siRNA四天後可以發現心臟中的eNOS增加，有助於降壓。Rrbp1-/-老鼠在進行心導管分析後，其心臟功能與一般老鼠沒有太大的差異，唯獨在施打一氧化氮合成酶抑制劑L-NAME時，收縮壓上升較一般老鼠明顯。 結論：本篇結果分別從抑制�剔除�過度表達的層面來探討。在老鼠心臟受到較輕微損傷時，rrbp1表達增加，可能參與心臟重塑的保護機制。在老鼠高血壓模式之下，給予siRNA注射的老鼠能透過增加NOS表達以達到降壓的效果。綜合實驗結果來看，rrbp1的調節對於心血管疾病進程的控制和疾病狀態與物種有關。而老鼠和人類的RRBP1與NOS之間的關聯性、以及物種間機制的差異還有待後續進一步釐清。

Introduction: The dramatic up-regulation of RRBP1 was also found in human dilated (DCM) and ischemic cardiomyopathy (ICM). Previous finding in our lab also revealed rrbp1 knockout may induce NOSs (eNOS and iNOS) expression, resulting in abnormal calcium handling. Aim: To examine the change of rrbp1 expression in mouse cardiovascular diseases, and to clarify the possible causal relationship of rrbp1 expression level and cell stress responses. Materials and Methods: We used C57BL/6 mice with chemical induced fibrosis or hypertension, to study the expression level of rrbp1 under disease model. And we used cardiac catheterization to measure cardiac function in rrbp1-/- mice (KO). Also we used HUVEC, HEK283T and HL-1 cardiomyocytes to investigate the impact of overexpression or knockdown RRBP1 on stress response and its correlation to NOS expression. Results: In mice with mild to moderate cardiac remodeling, the severity of cardiac fibrosis was positive correlation to the increased rrbp-1 expression in mice injected with 10 mg/kg ISO for 2-3 days. While the absence of rrbp-1 alteration was found in severe dilated heart failure mice suffering from consecutive two daily doses of 30 mg/kg. Though the induction of RRBP-1 overexpression could slightly increase eNOS expression in HL-1 and HUVEC cells, inducing RRBP1 overexpression in HEK293T cells did not enhance cell viability against hypoxia-reperfusion injury. However, in chronic angII-induced hypertension mice, intravenous injection of rrbp1 siRNA could significantly lowered blood pressure in association with cardiac eNOS up-regulation. In rrbp1-/- mice, there was no significant difference in the basal cardiac function compared to wild type mice. Furthermore, silencing RRBP-1 in HUVEC could only increase iNOS expression. Conclusion: Our results obtained from knockdown/knockout and overexpression experiments provide a comprehensive insight into the functional correlation of rrbp-1 expression levels in different cardiovascular diseases. The adaptive up-regulation of rrbp-1 was occurred only in moderately injured mice hearts undergoing compensatory remodeling. Administration of rrbp-1 siRNAs in hypertensive mice could lower blood pressure in association with the increase of cardiac NOSs expression. The functional alteration upon rrbp-1 expression for the purpose of controlling cardiovascular disease progression is dependent on not only disease status but also species. It remains further investigation to clarify the functional correlation of rrbp-1/RRBP-1 and NOSs as well as the underlying regulatory mechanisms among the cells from different species.