scholarly journals Tissue-Nonspecific Alkaline Phosphatase in Central Nervous System Health and Disease: A Focus on Brain Microvascular Endothelial Cells

2021 ◽  
Vol 22 (10) ◽  
pp. 5257
Author(s):  
Divine C. Nwafor ◽  
Allison L. Brichacek ◽  
Ahsan Ali ◽  
Candice M. Brown
Keyword(s):  
Alkaline Phosphatase ◽  
Endothelial Cells ◽  
Plasma Membranes ◽  
Bone Mineralization ◽  
Microvascular Endothelial Cells ◽  
Brain Microvascular Endothelial Cells ◽  
Cerebral Microvessels ◽  
Health And Disease ◽  
Tissue Nonspecific Alkaline Phosphatase ◽  
Microvascular Endothelial

Tissue-nonspecific alkaline phosphatase (TNAP) is an ectoenzyme bound to the plasma membranes of numerous cells via a glycosylphosphatidylinositol (GPI) moiety. TNAP’s function is well-recognized from earlier studies establishing its important role in bone mineralization. TNAP is also highly expressed in cerebral microvessels; however, its function in brain cerebral microvessels is poorly understood. In recent years, few studies have begun to delineate a role for TNAP in brain microvascular endothelial cells (BMECs)—a key component of cerebral microvessels. This review summarizes important information on the role of BMEC TNAP, and its implication in health and disease. Furthermore, we discuss current models and tools that may assist researchers in elucidating the function of TNAP in BMECs.

scholarly journals Brain endothelial cell tissue-nonspecific alkaline phosphatase (TNAP) activity promotes maintenance of barrier integrity via the ROCK pathway

2021 ◽  
Author(s):  
Divine C Nwafor ◽  
Allison L Brichacek ◽  
Wei Wang ◽  
Nina Bidwai ◽  
Christa L Lilly ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Endothelial Cells ◽  
Microvascular Endothelial Cells ◽  
Brain Microvascular Endothelial Cells ◽  
Barrier Dysfunction ◽  
Barrier Integrity ◽  
Cytoskeletal Remodeling ◽  
Conditional Deletion ◽  
Tissue Nonspecific Alkaline Phosphatase ◽  
Microvascular Endothelial

Blood-brain barrier (BBB) dysfunction is a key feature in many neuroinflammatory diseases. Yet, no therapies exist to effectively mitigate BBB dysfunction. A strategy to bridge this knowledge gap requires an examination of proteins localized to brain microvascular endothelial cells (BMECs) and evaluating their role in preserving barrier integrity. Tissue-nonspecific alkaline phosphatase (TNAP) is highly abundant in brain microvascular endothelial cells (BMECs); however, its function in BMECs remains unclear. We hypothesized that a loss or inhibition of TNAP activity on BMECs would impair barrier integrity through increased cytoskeletal remodeling driven by the Rho-associated protein kinase (ROCK) pathway. First, we examined barrier integrity in hCMEC/D3 cells treated with a TNAP inhibitor (TNAPi) and in primary BMECs (pBMECs) via the conditional deletion of TNAP in endothelial cells. Our results showed that both pharmacological inhibition and genetic conditional loss of TNAP significantly worsened endothelial barrier integrity compared to controls. Next, we examined the mechanisms through which TNAP activity exerts a protective phenotype on BMECs. Our results showed that hCMEC/D3 cells treated with TNAPi displayed remarkable phalloidin and vimentin cytoskeletal remodeling compared to control. We then examined the role of ROCK, a key player in cytoskeletal remodeling. Our results showed that TNAPi increased the expression of ROCK 1/2. Furthermore, inhibition of ROCK 1/2 with fasudil mitigated TNAPi-induced and VE-cKO barrier dysfunction. Collectively, our results support a novel mechanism through which loss of TNAP activity results in cerebrovascular dysfunction, and selective modulation of TNAP activity in BMECs may be a therapeutic strategy to improve BBB function.

scholarly journals Ultracytochemical characteristics of cultured goat brain microvascular endothelial cells [corrected]

1991 ◽  
Vol 39 (11) ◽  
pp. 1555-1563 ◽  
Author(s):  
A W Vorbrodt ◽  
R S Trowbridge
Keyword(s):  
Endothelial Cells ◽  
Plasma Membranes ◽  
Ricinus Communis ◽  
Enzymatic Activities ◽  
Gold Complex ◽  
Microvascular Endothelial Cells ◽  
Brain Microvascular Endothelial Cells ◽  
Microvascular Endothelium ◽  
Microvascular Endothelial

This ultrastructural study was undertaken to determine the localization of cytochemically demonstrable blood-brain barrier (BBB)-associated enzymatic activities and of some nonenzymatic constituents in goat [corrected] brain microvascular endothelial cells (ECs) growing in vitro. Positive reactions for alkaline phosphatase (AP), 5'-nucleotidase (5'N), transport ATPase (Na+,K(+)-ATPase), and adenosine diphosphatase (ADPase) were present on both apical and basolateral plasma membranes (PMs) of the ECs. The reaction for calcium-dependent ATPase (Ca(2+)-ATPase) was less intense and was restricted to basolateral PM and associated plasmalemmal pits. These cells also revealed an abundance of anionic sites labeled with cationic colloidal gold (CCG) and Ricinus communis agglutinin 120 (RCA)-binding sites, specific for beta-D-galactosyl residues, on the apical PM. The labeling of the apical PM with Ulex europaeus agglutinin (UEA)-gold complex, specific for alpha-L-fucosyl residues, was negligible. When compared with results of cytochemical examination of the ECs of goat [corrected] brain capillary in vivo, these observations indicate that although cells cultivated in vitro retain at confluence the enzymatic activities typical for BBB-type ECS, they lose their characteristic (polar) localization. This loss is interpreted as a reflection of lost functional polarity of the microvascular endothelium in vitro resulting from deprivation of the normal influence of the components of brain parenchyma.

scholarly journals Ubiquinone Metabolism and Transcription HIF-1 Targets Pathway Are Toxicity Signature Pathways Present in Extracellular Vesicles of Paraquat-Exposed Human Brain Microvascular Endothelial Cells

2021 ◽  
Vol 22 (10) ◽  
pp. 5065
Author(s):  
Tatjana Vujić ◽  
Domitille Schvartz ◽  
Anton Iliuk ◽  
Jean-Charles Sanchez
Keyword(s):  
Endothelial Cells ◽  
Human Brain ◽  
Extracellular Vesicles ◽  
Physiological State ◽  
Microvascular Endothelial Cells ◽  
Brain Microvascular Endothelial Cells ◽  
Cell Of Origin ◽  
Functional Changes ◽  
Data Independent Acquisition ◽  
Microvascular Endothelial

Over the last decade, the knowledge in extracellular vesicles (EVs) biogenesis and modulation has increasingly grown. As their content reflects the physiological state of their donor cells, these “intercellular messengers” progressively became a potential source of biomarker reflecting the host cell state. However, little is known about EVs released from the human brain microvascular endothelial cells (HBMECs). The current study aimed to isolate and characterize EVs from HBMECs and to analyze their EVs proteome modulation after paraquat (PQ) stimulation, a widely used herbicide known for its neurotoxic effect. Size distribution, concentration and presence of well-known EV markers were assessed. Identification and quantification of PQ-exposed EV proteins was conducted by data-independent acquisition mass spectrometry (DIA-MS). Signature pathways of PQ-treated EVs were analyzed by gene ontology terms and pathway enrichment. Results highlighted that EVs exposed to PQ have modulated pathways, namely the ubiquinone metabolism and the transcription HIF-1 targets. These pathways may be potential molecular signatures of the PQ-induced toxicity carried by EVs that are reflecting their cell of origin by transporting with them irreversible functional changes.

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