Related Experiment Video
Updated: Sep 18, 2025
A Microphysiological System to Study Leukocyte-Endothelial Cell Interaction during Inflammation
Published on: December 9, 2021
Endothelial HOXB9/SDC4 signaling exacerbates post-ischemic blood-brain and blood-spinal cord barrier disruption by
Li-Qing Wang1, Xiao-Yi Wang2, Zuo-Xu Fan2
1Department of Anesthesiology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003, China.
Insights
Homeobox B9 (HOXB9) upregulates Syndecan-4 (SDC4), disrupting the blood-brain barrier (BBB). Inhibiting HOXB9 reduces SDC4, protecting against stroke and spinal cord injury.
Area of Science:
- Neuroscience
- Molecular Biology
- Pathology
Background:
- Ischemic stroke is a leading cause of death, causing damage to the blood-brain barrier (BBB) and blood-spinal cord barrier (BSCB).
- Syndecan-4 (SDC4) plays a role in BBB integrity, but its precise mechanism remains unclear.
Purpose of the Study:
- To elucidate the mechanism by which SDC4 affects BBB integrity and function following ischemic stroke.
- To investigate the regulatory role of Homeobox B9 (HOXB9) in SDC4 expression and its downstream effects.
Main Methods:
- Established middle cerebral artery occlusion (MCAO) rat and oxygen-glucose deprivation/reoxygenation (OGD/R) cell models.
- Assessed BBB integrity using TEER, immunofluorescence, and Evans Blue assays.
- Investigated SDC4's effect on PKCα activation and HOXB9's transcriptional regulation of SDC4 via ChIP and dual-luciferase assays.
Main Results:
- SDC4 was upregulated in response to MCAO and OGD/R, leading to reduced cell viability, TEER, and tight junction proteins, while promoting PKCα activation.
- SDC4 interference improved BBB integrity, protected neuronal structure, and reduced inflammatory markers (IL-6, TNF-α).
- HOXB9, a transcription factor, was upregulated by OGD/R and directly targeted the SDC4 promoter, increasing SDC4 expression and exacerbating BBB damage.
Conclusions:
- HOXB9 acts as a key regulator of SDC4 transcription.
- Inhibiting HOXB9 reduces SDC4 expression, attenuates PKCα activation, and alleviates BBB disruption, spinal cord injury, and BSCB damage.
Background:
Ischemic stroke is one of the most deadly chronic diseases, it damages blood-brain barrier (BBB) and blood-spinal cord barrier (BSCB). Syndecan-4 (SDC4) affects BBB integrity and function, but the specific mechanism is unclear.
Methods:
The middle cerebral artery occlusion (MCAO) rat model and the oxygen-glucose deprivation/reoxygenation (OGD/R) cell model were conducted. The influences of SDC4 on the integrity and function of BBB were detected by the transmembrane resistance (TEER) assay, immunofluorescence staining and Evans Blue assay. Luxol Fast Blue staining was used to observe the changes of motoneurons structure. Additionally, the effect of SDC4 on protein kinase Cα (PKCα) activation was measured. Finally, the effect and mechanism of Homeobox B9 (HOXB9) on SDC4 was measured with chromatin immunoprecipitation assays and dual-luciferase reporter assay.
Results:
SDC4 was upregulated in brain of MCAO rat, hCMEC/D3 cells and rBMVEC cells treated with OGD/R. SDC4 overexpression reduced cell viability, TEER and the expression of tight junction proteins. Importantly, SDC4 overexpression promoted PKCα activation. SDC4 interference had the opposite effects. In vivo experiments, SDC4 interference hindered Evans Blue entering brain, protected neurons structure and reduced IL-6 and TNF-α levels. As the transcription factor of SDC4, HOXB9 was upregulated in hCMEC/D3 cells induced by OGD/R. HOXB9 overexpression promoted the expression of SDC4, reduced cell viability, TEER, and tight junction protein expressions. Importantly, HOXB9 interacts with SDC4 promoter region site 2 to affect SDC4 transcription.
Conclusion:
HOXB9 interference inhibited SDC4 transcription to attenuate PKCα activation, finally alleviate BBB disruption, spinal cord injury and BSCB damage.
More Related Videos
04:29Author Spotlight: Modeling Vascular Contributions to Alzheimer's Disease in Transgenic Mice
Published on: May 17, 2024
08:04Derivation, Expansion, Cryopreservation and Characterization of Brain Microvascular Endothelial Cells from Human Induced Pluripotent Stem Cells
Published on: November 19, 2020
Related Concept Videos
01:24Regulation of Angiogenesis and Blood Supply
00:49The Blood-brain Barrier