Search bioRxiv⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2023.01.23.525218

Endothelial vacuole membrane enriched aquaporins regulate microvascular lumenization in development and hyperglycemia

Chen, C.·Qin, Y.·Xu, Y.·Chen, L.·Wang, L.·Liu, D.
View original source ↗Export metadata ↓

Abstract

BackgroundIn patients with diabetic microvascular complications, decreased perfusion or vascular occlusion, caused by reduced vascular diameter, is a common characteristic that will lead to insufficient blood supply. However, the regulatory mechanism remains undetermined and the treatment approach is lacking. MethodsGene expression of Aquaporin 1 (AQP1) was compared between diabetic and non-diabetic human retina samples. Confocal live imaging analysis of zebrafish was utilized to investigate the hyperglycemia-induced alterations in vascular morphology. Transcriptomic and single-cell RNA sequencing, in situ hybridization, and quantitative PCR were used to analyze gene expressions. Gene knock-out zebrafish and stable transgenic lines were established for functional analysis. Human embryonic stem cells (H1 line), H1-derived endothelial cells (ECs), human umbilical vein endothelial cells (HUVECs), and human retinal microvascular endothelial cells (HRMECs) were used for functional analysis. ResultsFirstly, we found that the expression of human AQP1 was downregulated in diabetic human retina samples (49 healthy vs. 54 diabetic samples) and high-glucose-treated human retinal microvascular endothelial cells. Then, we observed the reduction of vascular diameter and compromised perfusion in high glucose-treated zebrafish embryos. Two aquaporins (aqp1a.1 and aqp8a.1), highly enriched in ECs, were significantly down-regulated under hyperglycemic conditions. Aqp1a.1 and/or aqp8a.1 loss-of-function leaded to reduction in intersegmental vessel diameters, recapitulating the phenotype of the hyperglycemic zebrafish model. Overexpressing aqp1a.1/aqp8a.1 in zebrafish ECs promoted the enlargement of microvascular diameters. Moreover, the reduced vessel diameters induced by high-glucose treatment was rescued by aquaporin overexpression. In addition, both aqp1a.1 and apq8a.1 were localized in the intracellular vacuoles in cultured ECs as well as the ECs of sprouting ISVs, and loss of Aqps caused the reduction of those vacuoles, which was required for lumenization. Loss of AQP1 had no influence on EC differentiation from human stem cells but strongly inhibited the vascular tube formation of differentiated ECs. ConclusionsEC-enriched aquaporins regulate intracellular vacuole-mediated blood vessel diameter hyperglycemia. All of these suggest that EC-expressed aquaporins might be potential targets for gene therapy to cure diabetes-related vascular perfusion defects.

Source connections

Explore related subjects

cell biologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Chen, C., Qin, Y., Xu, Y., Chen, L., Wang, L., Liu, D.. 2023-01-24. Endothelial vacuole membrane enriched aquaporins regulate microvascular lumenization in development and hyperglycemia. https://doi.org/10.1101/2023.01.23.525218

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Functional characterization of Rho GTPase activating proteins SYDE1 and SYDE2

The human genome encodes more than 60 proteins containing Rho GTPase activating protein (RhoGAP) domains, many of which remain understudied with respect to their target specificity and biological roles. SYDE1 and SYDE2 are two such orphan RhoGAPs, for which there are few studies characterizing their biochemical and cellular functions and conflicting reports identifying their cognate GTPases. We previously identified SYDE1 and SYDE2 in a screen for substrates of the c-Jun N-terminal kinases. Here, we show that SYDE1 and SYDE2 are preferentially phosphorylated by JNK1 relative to other mitogen-activated protein kinases (MAPKs) at sites proximal to a kinase docking region. Purified SYDE1 and SYDE2 are shown to have significant catalytic GAP activity toward RhoA, Rac1, and Cdc42. However, neither up- nor down-regulation of SYDE1/2 expression leads to detectable changes in bulk GTP loading of any of these GTPases. Nevertheless, we demonstrate that SYDE1 and SYDE2, in a partially GAP-dependent manner, increase cell spreading and number of focal adhesions, and promote more directionally persistent migration in HEK293 cells. Together, these findings establish SYDE1 and SYDE2 as robust JNK substrates with catalytic activity toward a set of Rho GTPases and reveal basic functions of SYDE1 and SYDE2 in regulating cell morphology, adhesion, and migration.

cell biology↗
bioRxiv2026

The filopodial scaffold polyphosphate dictates cell adhesion-versus-invasion decisions

Inorganic polyphosphate (polyP) is an ancient polymer conserved across all life, serving cell type and location specific functions in every major compartment. Yet its role at the plasma membrane, where it accumulates to peak levels in many primary cells, is largely unknown. Here we identify polyP as a stabilizing component of filopodia, actin based membrane protrusions that govern cell adhesion, contact inhibition, and chemotaxis. Elevating cellular polyP increases filopodial stability and enhances cell adhesion, whereas reducing polyP accelerates filopodial disassembly and promotes cell migration. Mechanistically, we find that polyP acts as a structural filopodial scaffold, recruiting and organizing IRSp53, a membrane curvature inducing protein. We show that metastatic fibroblasts and breast cancer organoids carry markedly reduced and intracellularly reorganized polyP levels relative to their non transformed counterparts. Restoring endogenous polyP via lipid nanoparticle delivery suppresses their invasive phenotypes and reverses prometastatic gene expression signatures, implicating polyP as a primordial tumor suppressor.

cell biology↗
bioRxiv2026

Mitochondrial transfer mediates metabolic communication between beta cells and islet macrophages

Pancreatic islet macrophages support islet homeostasis and adapt their metabolic program in response to environmental cues, including beta cell released factors. Intercellular mitochondrial transfer is a biological process that modulates cellular responses. To test whether beta cells, which are strongly secretory, transfer mitochondria to islet macrophages, we generated mice with beta cell-specific expression of mitochondrial GFP (PhAMfloxIns1Cre). We demonstrate that beta cells transfer mitochondria to islet macrophages in vivo and in vitro. Diabetogenic stressors did not alter the frequency of mitochondrial transfer and macrophages containing beta cell-derived GFP exhibit increased protein synthesis rates. RNA-seq identified upregulation of activity-regulated cytoskeleton associated protein (Arc) in macrophages receiving beta cell-derived mitochondria, while disruption of actin cytoskeleton dynamics prevented mitochondrial transfer. Together, these findings identify mitochondrial transfer as a previously unrecognized mechanism of beta cell-macrophage communication that may contribute to islet homeostasis and immune regulation.

cell biology↗