Biology subjects

McCurdy, S.

Publications and source records attributed to McCurdy, S..

4 recordsLinked to original sources

bioRxiv2025

Silencing KRIT1 Partially Reverses the Effects of Disturbed Flow onThe Endothelial Cell Transcriptome

BackgroundEndothelial cells respond to forces generated by laminar blood flow with changes in vasodilation, anticoagulant, fibrinolytic, or anti-inflammatory functions which preserve vessel patency. These responses to flow sheer stress are primarily mediated by the modulation of transcription factors Kruppel-like factors 2 and 4 (KLF2 and KLF4). Notably, disturbed flow patterns, which are found in vascular areas predisposed to atherosclerosis, significantly reduce the endothelial expression of KLF2 and KLF4, resulting in changes in the transcriptome that exacerbate inflammation and thrombosis. The endothelial CCM complex, comprising KRIT1, CCM2, and CCM3, suppresses the expression of KLF2 and KLF4. Loss of function of the CCM complex has recently been suggested to protect from coronary atherosclerosis in humans. We thus hypothesized that silencing of KRIT1, the central scaffold of the CCM complex, can normalize the atherogenic effects of disturbed flow on the human endothelial transcriptome MethodsBulk RNA sequencing (RNA-seq) was conducted on human umbilical vein endothelial cells (HUVECs) after the expression of KRIT1 was silenced using specific siRNAs. The endothelial cells were exposed to three different conditions for 24 hours: pulsatile shear stress (laminar flow), oscillatory shear stress (disturbed flow), and static conditions (no flow). ResultsWe found that silencing KRIT1 expression in HUVECs restored the expression of the transcription factors KLF2 and KLF4 under oscillatory shear stress. This treatment resulted in a transcriptomic profile similar to that of endothelial cells under pulsatile shear stress. These findings suggest that inhibition of the CCM complex in endothelium plays a vasoprotective role by reactivating a protective gene program to help endothelial cells resist disturbed blood flow. ConclusionsTargeting CCM genes can activate well-known vasoprotective gene programs that enhance endothelial resilience to inflammation, hypoxia, and angiogenesis under disturbed flow conditions, providing a novel pathway for preventing atherosclerosis. Graphic abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=127 SRC="FIGDIR/small/642862v1_ufig1.gif" ALT="Figure 1"> View larger version (48K): org.highwire.dtl.DTLVardef@a20119org.highwire.dtl.DTLVardef@1f62f68org.highwire.dtl.DTLVardef@1a26d71org.highwire.dtl.DTLVardef@bf3c82_HPS_FORMAT_FIGEXP M_FIG C_FIG Endothelial cells respond to blood flow by expressing transcription factors such as Kruppel-Like Factors 2 and 4 (KLF2 and KLF4). Under oscillatory shear stress (OS) conditions, characterized by disturbed flow, KLF2 and KLF4 are suppressed in endothelial cells, which is linked to an atheroprone gene program that includes increased inflammation and risk of atherosclerosis (unhealthy endothelium). Our work shows that silencing of endothelial KRIT1 under OS increases expression of KLF2 and KLF4 mRNA levels as well as the expression of a protective gene program associated with resilience to inflammation, hypoxia, and angiogenesis, similar to those observed under pulsatile shear stress conditions (healthy endothelium).

pathology↗

bioRxiv2024

Genetic Inactivation of the beta1 adrenergic receptor prevents Cerebral Cavernous Malformations in zebrafish

Propranolol reduces experimental murine cerebral cavernous malformations (CCMs) and prevents embryonic caudal venous plexus (CVP) lesions in zebrafish that follow mosaic inactivation of ccm2. Because morpholino silencing of the {beta}1 adrenergic receptor (adrb1) prevents the embryonic CVP lesion, we proposed that adrb1 plays a role in CCM pathogenesis. Here we report that adrb1-/- zebrafish exhibited 86% fewer CVP lesions and 87% reduction of CCM lesion volume relative to wild type brood mates at 2dpf and 8-10 weeks stage, respectively. Treatment with metoprolol, a {beta}1 selective antagonist, yielded a similar reduction in CCM lesion volume. Adrb1-/- zebrafish embryos exhibited reduced heart rate and contractility and reduced CVP blood flow. Similarly, slowing the heart and eliminating the blood flow in CVP by administration of 2,3-BDM suppressed the CVP lesion. In sum, our findings provide genetic and pharmacological evidence that the therapeutic effect of propranolol on CCM is achieved through {beta}1 receptor antagonism.

developmental biology↗

bioRxiv2021

Non cell-autonomous effect of astrocytes on cerebral cavernous malformations

Cerebral cavernous malformations (CCMs) are common neurovascular lesions caused by loss-of-function mutations in one of three genes, including KRIT1 (CCM1), CCM2, and PDCD10 (CCM3), and generally regarded as an endothelial cell-autonomous disease. Here we report that proliferative astrocytes play a critical role in CCM pathogenesis by serving as a major source of VEGF during CCM lesion formation. An increase in astrocyte VEGF synthesis is driven by endothelial nitric oxide (NO) generated as a consequence of KLF2 and KLF4-dependent elevation of eNOS in CCM endothelium. The increased brain endothelial production of NO stabilizes HIF-1 in astrocytes, resulting in increased VEGF production and expression of a "hypoxic" program under normoxic conditions. We show that the upregulation of cyclooxygenase-2 (COX-2), a direct HIF-1 target gene and a known component of the hypoxic program, contributes to the development of CCM lesions because the administration of a COX-2 inhibitor significantly prevents progression of CCM lesions. Thus, non-cell-autonomous crosstalk between CCM endothelium and astrocytes propels vascular lesion development, and components of the hypoxic program represent potential therapeutic targets for CCMs.

neuroscience↗

bioRxiv2017

Column subset selection for single-cell RNA-Seq clustering

The first step in the analysis of single-cell RNA sequencing (scRNA-Seq) is dimensionality reduction, which reduces noise and simplifies data visualization. However, techniques such as principal components analysis (PCA) fail to preserve non-negativity and sparsity structures present in the original matrices, and the coordinates of projected cells are not easily interpretable. Commonly used thresholding methods avoid those pitfalls, but ignore collinearity and covariance in the original matrix. We show that a deterministic column subset selection (DCSS) method possesses many of the favorable properties of PCA and common thresholding methods, while avoiding pitfalls from both. We derive new spectral bounds for DCSS. We apply DCSS to two measures of gene expression from two scRNA-Seq experiments with different clustering workflows, and compare to three thresholding methods. In each case study, the clusters based on the small subset of the complete gene expression profile selected by DCSS are similar to clusters produced from the full set. The resulting clusters are informative for cell type.

bioinformatics↗