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Accumulation of Notch3 extracellular domain and not aberrant NOTCH3 signaling is the key driver of CADASIL arterial pathology

ABSTRACT: Loss of arterial smooth muscle cells (SMCs) and abnormal accumulation of the extracellular domain of the NOTCH3 (Notch3ECD) receptor are the two core features of CADASIL, the most common genetic cerebral small vessel disease. Although CADASIL is known to be caused by highly stereotyped dominant mutations in NOTCH3, the relationship between NOTCH3 receptor activity, Notch3ECD accumulation and arterial SMC loss has remained elusive, hampering the development of disease-modifying therapies. Using novel histopathological and multiscale imaging modalities, we quantified previously undetectable CADASIL-driven focal arterial SMC loss in the central nervous system of mice expressing the archetypal Arg169Cys CADASIL mutation. Notably, we found more severe arterial pathology and greater Notch3ECD accumulation in transgenic model mice overexpressing the mutation on a homozygous wild-type Notch3 background (TgNotch3R169C) than in knock-in model Notch3R170C/R170C mice expressing this mutation without a wild-type Notch3 copy. We further showed that wild-type Notch3ECD co-aggregated with mutant Notch3ECD and that elimination of one copy of wild-type Notch3 in TgNotch3R169C mice was sufficient to attenuate Notch3ECD accumulation and arterial pathology. Importantly, RNA sequencing revealed no substantial change in the expression of Notch3-regulated genes in TgNotch3R169C brain arteries. Collectively, our results provide compelling evidence that Notch3ECD accumulation, involving mutant and wild-type NOTCH3, and not aberrant NOTCH3 signaling, is the key driver of arterial SMC loss in CADASIL, thus identifying NOTCH3-lowering approaches as candidate therapeutic strategies.

ORGANISM(S): Mus musculus

PROVIDER: GSE242794 | GEO | 2024/04/17

REPOSITORIES: GEO

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Project description:While most cases of vascular dementia represent complex interactions between host genetics and environmental factors, mendelian forms of vascular dementia also exist. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), is a mendelian disease characterized by progressive vascular deterioration, cognitive deficits, and strokes. Mutations in the NOTCH3 receptor underlies the pathologies in CADASIL. NOTCH3 is primarily expressed in vascular smooth muscle cell (vSMC) and its’ expression is critical for differentiation and functional integrity of arterial vSMCs, albeit through unclear mechanism(s). To elucidate the contribution of NOTCH3 in the maintenance of cerebral vascular architecture and function, we performed micro-computed tomography (micro-CT) on the brains of aged Notch3-deficient animals. Micro-CT assessment of the cerebral vasculature architecture showed significant abnormalities including severe vessel dilation and tortuosity (dolicoectasia) of the middle cerebral artery and its branches in the Notch3-/- compared to aged-match controls. To identify the molecular pathway from NOTCH3 dysregulation to the observed cerebral vascular dysfunction, we performed single-cell RNASeq on cerebral arteries isolated from young (4w) and old (104w) Notch3-/- animals. Evaluation of the vSMC-specific transcriptomes indicated significant loss of proteins associated with muscle contraction and increased extracellular matrix production in animals that lack NOTCH3. Using a combination of immunofluorescence microscopy and in vitro functional assays, we confirmed that continued expression of Notch3 is a critical requirement for maintenance of vSMC contractile function. Impaired contractility also affected flow of cerebrospinal fluid in the parenchyma of Notch3-/- . MRI and behavioral assessments were performed in the Notch3-/- animals to elucidate the relationship between impaired vascular contractility to cognitive function. Taken together these findings link the molecular dysfunction of NOTCH3 through its regulation of vascular contractility and cerebral vessel architecture to altered neurological function and clarify the molecular pathways to cellular pathology of Notch3 driven dementias.

Project description:To determine the role of NOTCH3 in human esophageal epitheila homeostasis/squamous cell differentiation Zinc finger E-box binding (ZEB) proteins ZEB1 and ZEB2 are transcription factors essential in transforming growth factor (TGF)-Î²-mediated epithelial to mesenchymal transition (EMT), senescence and cancer stem cell maintenance through mutual negative regulation of the microRNA (miR)-200 family members. However, little is known as to how ZEB expressing tumor cells may emerge during invasive growth. We find that canonical Notch signaling prevents expansion of a unique subset of cells expressing ZEBs through NOTCH3 (N3). In primary esophageal squamous cell carcinoma (ESCC), ZEB1 is induced in tumor cells displaying EMT-like dedifferentiation at the invasive front of tumor nests with reciprocal downregulation of the miR-200. ZEB expression was associated with the lack of cellular capability of undergoing squamous differentiation through dysfunction of N3, implicated at the onset of normal esophageal squamous differentiation. Dominant-negative Mastermind-like1 (DNMAML1), a genetic pan-notch inhibitor, prevented CSL-dependent transcription, resulting in suppression of N3 expression and squamous differentiation while enriching EMT competent cells with robust upregulation of ZEBs and downregulation of the miR-200. Such a cell population demonstrated enhanced anchorage independent growth as well as tumor formation in nude mice. RNA interference (RNAi) experiments documented the requirement of ZEBs in TGF-Î²-mediated EMT. Invasive growth and impaired squamous differentiation was recapitulated upon Notch inhibition in organotypic 3D culture, a form of human tissue engineering. Finally, RNAi experiments revealed N3 as a key factor limiting the expansion of the ZEB expressing cells, providing novel mechanistic insights into the role of Notch signaling in ESCC cell fate regulation and disease progression. NOTCH3 was knockdown stably in immortalized human esophageal keratinocytes EPC2-hTERTstably by lentivirus-mediated gene transfer with shRNA directed against NOTCH3 (Open BiosystemsV2LHS_229748). A scrambled shRNA (Open Biosystems RHS4346) served as acontrol. Cells were stimulated with 0.6 mM calcium chloride to induce squamous cell differentiation for 72 hrs (0.09 mM Calcium Chloride as a unstimulated control) as described in Gastroenterology. 2010 Dec;139(6):2113-23 by Ohashi et al.

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Accumulation of Notch3 extracellular domain and not aberrant NOTCH3 signaling is the key driver of CADASIL arterial pathology

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