Structural insights into plasmalemma vesicle-associated protein (PLVAP): Implications for vascular endothelial diaphragms and fenestrae

Abstract

In many organs, small openings across capillary endothelial cells (ECs) allow the diffusion of low–molecular weight compounds and small proteins between the blood and tissue spaces. These openings contain a diaphragm composed of radially arranged fibers, and current evidence suggests that a single-span type II transmembrane protein, plasmalemma vesicle-associated protein-1 (PLVAP), constitutes these fibers. Here, we present the three-dimensional crystal structure of an 89-amino acid segment of the PLVAP extracellular domain (ECD) and show that it adopts a parallel dimeric alpha-helical coiled-coil configuration with five interchain disulfide bonds. The structure was solved using single-wavelength anomalous diffraction from sulfur-containing residues (sulfur SAD) to generate phase information. Biochemical and circular dichroism (CD) experiments show that a second PLVAP ECD segment also has a parallel dimeric alpha-helical configuration—presumably a coiled coil—held together with interchain disulfide bonds. Overall, ~2/3 of the ~390 amino acids within the PLVAP ECD adopt a helical configuration, as determined by CD. We also determined the sequence and epitope of MECA-32, an anti-PLVAP antibody. Taken together, these data lend strong support to the model of capillary diaphragms formulated by Tse and Stan in which approximately ten PLVAP dimers are arranged within each 60- to 80-nm-diameter opening like the spokes of a bicycle wheel. Passage of molecules through the wedge-shaped pores is presumably determined both by the length of PLVAP—i.e., the long dimension of the pore—and by the chemical properties of amino acid side chains and N-linked glycans on the solvent-accessible faces of PLVAP.

Single-cell transcriptomics analysis of proliferative diabetic retinopathy fibrovascular membranes reveals AEBP1 as fibrogenesis modulator

“…In addition, we found expression of the leakage marker PLVAP in all endothelial cells ( Figure 3D ), sustaining the hypothesis that those cells have lost their retina capillary phenotype. PLVAP specifically localizes to diaphragms of fenestrated endothelial cells such as the choriocapillaris ( 17 , 18 ); it is typically expressed in vascular beds performing high filtration, secretion, or transendothelial transport. It is absent in endothelial cells where barrier properties are critical, such as the BRB.…”

“…We next explored the functional genes of endothelial cells and found abnormally low expression levels of several critical BRB genes -including ANGPT2 and most of the tight junctions such as CLDN1, CLDN12, OCLN, CNG, TPJ2, ILDR2, and AXIN1-2 -and upregulation of leakage markers, such as PLVAP in all endothelial cell types, consistent with the pathological nature of these endothelial cell in newly formed blood vessels. PLVAP has been shown to be upregulated in the BRB in pathological conditions, whereas physiologically, it is only expressed in fenestrated endothelial beds and not in those with a critical barrier functions (17)(18)(19). Interestingly, a recent study showed that loss of endothelial angiopoietin 2 was responsible for abnormal brain vascular morphology, increased vascular leakage, abnormalities of endothelial cell shape, and alteration of the distribution of claudin 5, an important tight junction of the blood-brain barrier (37).…”

Vascular dysfunction is at the onset of oxaliplatin-induced peripheral neuropathy symptoms in mice

“…2B). For the snBV-enriched DEGs, Fabp4 and Plvap were chosen according to their distinct levels of expression (Fig 2B) and respective role in active (Fabp4 coding for Fatty Acid Binding Protein 4 (FABP4); Elmasri et al, 2009;Jabs et al, 2018) or passive (Plvap coding for Plasmalemma vesicle-associated protein (PLVAP); Chang et al, 2023) transport across the vessel wall. In addition, the structural and functional integrity of the BBB is directly controlled by Tjp/ZO-1positive tight junctions between brain endothelial cells (Huber et al, 2001).…”

ABCG2-Expressing Clonal Repopulating Endothelial Cells Serve to Form and Maintain Blood Vessels

“…The differential expression analysis showed that in the adult heart, the expression of 364 genes was more activated in Abc-CRECs than in mature ECs (Figure 5A; false discovery rate<0.05, log fold change>1). Among them were many genes that are involved in vessel development and stem cell maintenance, such as Notch2, Piezo2, Sox9, Myc, Gata4, Lrg1, Plvap, and Dkk3 [28][29][30][31][32][33][34] (Figure 5A). Pathway analysis showed that in adult heart AbcCRECs, genes involved in cell proliferation and cell cycle progression pathways were downregulated (Figure 5B), consistent with the results that AbcCRECs remain quiescent in adult cardiac blood vessels at steady state (Figure 4D and 4E).…”