Novel Knock in Mutation Rat Model for CARASIL

脑部小血管疾病(CSVD)是血管认知障碍和痴呆的主要原因 (VCID)在老年人中，是相当数量的缺血性和出血性中风的原因，并存在于 阿尔茨海默病及相关疾病(ADRD)。CSVD大致分为两类：1)淀粉样脑血管病 包括散发性和家族性脑淀粉样血管病(CAA)和ADRD，以及2)非淀粉样脑血管病 CSVD涉及常见情况，如高血压、糖尿病、动脉硬化和一些罕见的 单基因遗传性形式，包括伴有皮质下梗塞的常染色体隐性遗传性脑动脉病和 白质脑病(CARASIL)是一种罕见的常染色体隐性遗传性非高血压CSVD 表现为早期成人起病的VCID，步态障碍，脱发和脊椎病。磁共振成像 CARASIL患者的(MRI)研究显示明显的白质(WM)改变，包括多发性腔隙 梗塞，广泛的西医损害，主要累及基底节和脑干，在某些情况下， 皮质下脑微出血。西医损害似乎是由小血管损伤引起的，其特征是 广泛的脑动脉平滑肌细胞丢失，壁细胞外基质丢失和增厚 内弹力板碎裂。尽管单基因形式的CSVD很少见，但它们有许多共同的临床特征 以及更常见的散发性CSVD的神经病理特征，包括脑白质损害、脑 脑梗塞、脑出血和VCID。 以前的研究表明，CARASIL是由高度保守的HIGH中的特定突变引起的 温度需求丝氨酸蛋白酶A1(HTRA1)基因，显著降低或取消丝氨酸蛋白酶 HTRA1蛋白的活性，并被认为导致导致平滑肌的正常TGFb信号的中断 CARASIL患者的变性和其他脑动脉病变。CARASIL的机理研究是 由于缺乏有效的动物模型来忠实地概括人类疾病的病理特征，这一研究受到阻碍。 因此，这一探索性提案的总体目标是产生并表征一种新的老鼠 在内源性大鼠hTRA1中引入特异性CARASIL突变(R302Q)建立CARASIL模型 消除丝氨酸蛋白酶活性的基因。为了实现这一总体目标，我们提出了以下建议 三组实验：首先，我们将对一个新的突变体进行分子和病理特征分析 CARASIL的“敲入”大鼠模型。第二，我们将确定新出现的CSVD病理的后果 关于新型CARASIL大鼠的高级认知和运动功能。最后，我们将进行神经成像 在新的CARASIL中确定新出现的CSVD对MRI所定义的脑病理的影响的研究 老鼠。这项工作的成功完成将为CSVD领域提供一种新颖而独特的动物模型 更充分地了解这种情况如何导致脑动脉病、WM损害和VCID。此外，它还 将提供一个新的平台来研究针对VCID和ADRD的这些病理的治疗策略。

Cerebral small vessel diseases (CSVD) are a major cause of vascular cognitive impairment and dementia (VCID) in the elderly, account for a significant number of ischemic and hemorrhagic strokes and are present in Alzheimer’s disease and related disorders (ADRD). CSVDs broadly fall into two classes: 1) amyloidal CVSD including sporadic and familial forms of cerebral amyloid angiopathy (CAA) and ADRD and 2) non-amyloidal CSVD involving common conditions such as hypertension, diabetes, arteriolosclerosis and a number of rare monogenic hereditary forms that includes cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL), which is a rare autosomal recessive, inherited non-hypertensive CSVD that presents with early adult-onset VCID, gait disturbances, alopecia and spondylosis. Magnetic resonance imaging (MRI) studies of CARASIL patients show pronounced white matter (WM) changes including multiple lacunar infarcts, extensive WM lesions predominantly involving basal ganglia and brain stem and, in some cases, subcortical cerebral microbleeds. The WM lesions appear to result from small vessel damage characterized by extensive loss of cerebral arterial smooth muscle cells, loss of mural extracellular matrix and thickening and fragmentation of the internal elastic lamina. Although monogenic forms of CSVD are rare they share many clinical and neuropathological features with more common sporadic CSVDs including white matter damage, cerebral infarcts, cerebral bleeds and VCID. Previous studies have revealed that CARASIL results from specific mutations in the highly conserved high temperature requirement serine proteinase A1 (htra1) gene that markedly reduce or abolish the serine proteinase activity of Htra1 protein and believed to cause disruption of normal TGFb signaling that leads to smooth muscle degeneration and other cerebral arteriopathies in CARASIL patients. Mechanistic studies of CARASIL are hindered by the lack of effective animal models that faithfully recapitulate pathological features of human disease. Accordingly, the overall aim of this exploratory proposal is to generate and characterize a novel rat model of CARASIL by introducing a specific CARASIL mutation (R302Q) in the endogenous rat htra1 gene that will eliminate serine proteinase activity. To accomplish this overall goal, we propose the following three sets of experiments: First, we will conduct molecular and pathological characterization of a novel mutant ‘knock in’ rat model for CARASIL. Second, we will determine the consequences of emerging CSVD pathology on advanced cognitive and motor functions in the novel CARASIL rats. Lastly, we will perform neuroimaging studies to determine the impact of emerging CSVD on brain pathology as defined by MRI in the novel CARASIL rats. Successful completion of this work will provide a novel and unique animal model to the field of CSVD to more fully understand how this condition contributes to cerebral arteriopathy, WM damage and VCID. Further, it will provide a novel platform to investigate therapeutic strategies to target these pathologies in VCID and ADRD.