KANK4 Promotes Arteriogenesis by Potentiating VEGFR2 Signaling in a TALIN-1-Dependent Manner.

BACKGROUND: Arteriogenesis plays a critical role in maintaining adequate tissue blood supply and is related to a favorable prognosis in arterial occlusive diseases. Strategies aimed at promoting arteriogenesis have thus far not been successful because the factors involved in arteriogenesis remain incompletely understood. Previous studies suggest that evolutionarily conserved KANK4 (KN motif and ankyrin repeat domain-containing proteins 4) might involve in vertebrate vessel development. However, how the KANK4 regulates vessel function remains unknown. We aim to determine the role of endothelial cell-specifically expressed KANK4 in arteriogenesis. METHODS: The role of KANK4 in regulating arteriogenesis was evaluated using Kank4-/- and KANK4iECOE mice. Molecular mechanisms underlying KANK4-potentiated arteriogenesis were investigated by employing RNA transcriptomic profiling and mass spectrometry analysis. RESULTS: By analyzing Kank4-EGFP reporter mice, we showed that KANK4 was specifically expressed in endothelial cells. In particular, KANK4 displayed a dynamic expression pattern from being ubiquitously expressed in all endothelial cells of the developing vasculature to being explicitly expressed in the endothelial cells of arterioles and arteries in matured vessels. In vitro microfluidic chip-based vascular morphology analysis and in vivo hindlimb ischemia assays using Kank4-/- and KANK4iECOE mice demonstrated that deletion of KANK4 impaired collateral artery growth and the recovery of blood perfusion, whereas KANK4 overexpression leads to increased vessel caliber and blood perfusion. Bulk RNA sequencing and Co-immunoprecipitation/mass spectrometry (Co-IP/MS) analysis identified that KANK4 promoted EC proliferation and collateral artery remodeling through coupling VEGFR2 (vascular endothelial growth factor receptor 2) to TALIN-1, which augmented the activation of the VEGFR2 signaling cascade. CONCLUSIONS: This study reveals a novel role for KANK4 in arteriogenesis in response to ischemia. KANK4 links VEGFR2 to TALIN-1, resulting in enhanced VEGFR2 activation and increased EC proliferation, highlighting that KANK4 is a potential therapeutic target for promoting arteriogenesis for arterial occlusive diseases.

Single-Cell Transcriptomic Analysis Reveals a Hepatic Stellate Cell-Activation Roadmap and Myofibroblast Origin During Liver Fibrosis in Mice.

BACKGROUND AND AIMS: HSCs and portal fibroblasts (PFs) are the major sources of collagen-producing myofibroblasts during liver fibrosis, depending on different etiologies. However, the mechanisms by which their dynamic gene expression directs the transition from the quiescent to the activated state-as well as their contributions to fibrotic myofibroblasts-remain unclear. Here, we analyze the activation of HSCs and PFs in CCL4 -induced and bile duct ligation-induced fibrosis mouse models, using single-cell RNA sequencing and lineage tracing. APPROACH AND RESULTS: We demonstrate that HSCs, rather than PFs, undergo dramatic transcriptomic changes, with the sequential activation of inflammatory, migrative, and extracellular matrix-producing programs. The data also reveal that HSCs are the exclusive source of myofibroblasts in CCL4 -treated liver, while PFs are the major source of myofibroblasts in early cholestatic liver fibrosis. Single-cell and lineage-tracing analysis also uncovers differential gene-expression features between HSCs and PFs; for example, nitric oxide receptor soluble guanylate cyclase is exclusively expressed in HSCs, but not in PFs. The soluble guanylate cyclase stimulator Riociguat potently reduced liver fibrosis in CCL4 -treated livers but showed no therapeutic efficacy in bile duct ligation livers. CONCLUSIONS: This study provides a transcriptional roadmap for the activation of HSCs during liver fibrosis and yields comprehensive evidence that the differential transcriptomic features of HSCs and PFs, along with their relative contributions to liver fibrosis of different etiologies, should be considered in developing effective antifibrotic therapeutic strategies.

Synthesis, Characterization, and Properties of Three-Dimensional Analogues of 9-Borafluorenes.

Three-dimensional (3D) analogues of 9-borafluorenes, (C2B10H10)2BR (R = Cl (1), Br (2), H (3, merely as ether or silane adduct), phenyl (4), mesityl (5)), were synthesized and fully characterized. Gutmann-Beckett and computational fluoride/hydride ion affinity (FIA/HIA) studies confirmed the Lewis superacidity of 1-4, with the Lewis acidity of 1-3 being higher than that of the corresponding 3D analogues of 9,10-diboraanthracenes (DBA). The phenyl group and the C4B borole unit are nearly coplanar in the solid state, while the rotation of the mesityl group of 5 is hindered, forcing 5 to adopt a large C4B/Mes dihedral angle, which leads to distinct properties: air-stable and bluish-violet fluorescence arising from the intramolecular charge-transfer (ICT) transition. The 29Si NMR spectra indicated a high silylium cation character of 3·Et3SiH. The reaction of 4 with Ph3CBr yielded (Ph3C)+[(C2B10H10)2B(Ph)Br]- (6). The 4/PPh3 Lewis pair was capable of splitting dihydrogen and Si-H bond of triethylsilane.

A Three-Dimensional Inorganic Analogue of 9,10-Diazido-9,10-Diboraanthracene: A Lewis Superacidic Azido Borane with Reactivity and Stability.

Herein, we report the facile synthesis of a three-dimensional (3D) inorganic analogue of 9,10-diazido-9,10-dihydrodiboraantracene, which turned out to be a monomer in both the solid and solution state, and thermally stable up to 230 °C, representing a rare example of azido borane with boosted Lewis acidity and stability in one. Apart from the classical acid-base and Staudinger reactions, E-H bond activation (E=B, Si, Ge) was investigated. While the reaction with B-H (9-borabicyclo[3.3.1]nonane) led directly to the 1,1-addition on Nα upon N2 elimination, the Si-H (Et3 SiH, PhMe2 SiH) activation proceeded stepwise via 1,2-addition, with the key intermediates 5int and 6int being isolated and characterized. In contrast, the cooperative Ge-H was reversible and stayed at the 1,2-addition step.

Synthesis, Characterization, and Density Functional Theory Studies of Three-Dimensional Inorganic Analogues of 9,10-Diboraanthracene-A New Class of Lewis Superacids.

The three-dimensional inorganic analogues of 9,10-diboraanthracene, B2X2(C2B10H10)2 (X = Cl, 1; X = Br, 2), were attained by salt elimination of Li2C2B10H10 and trihaloboranes. The methyl- and phenyl-substituted compounds B2Me2(C2B10H10)2 (3) and B2Ph2(C2B10H10)2 (4) were obtained by treating 1 or 2 with the corresponding Grignard reagents. These compounds were fully characterized by NMR, cyclic voltammetry (CV), IR, and single-crystal X-ray diffraction analyses. Experimental (CV and Gutmann-Beckett method) and computational (fluoride ion affinity, hydride ion affinity and LUMO energy) results suggest that the order of Lewis acidity is 2 > 1 > 4 > 3 > SbF5. Treatment of 1 or 2 with HSiEt3 gave a rare neutral borane-silane adduct, (Et3SiH)2B2H2(C2B10H10)2 (5). The equilibrium of 5 in solution was thoroughly investigated by spectroscopy and quantum calculations.

Synthesis and reactivity of an N-heterocyclic carbene-stabilized diazoborane.

Diazo compounds and organic azides are widely used as reagents for accessing valuable molecules in multiple areas of fundamental and applied chemistry. Their capacity to undergo versatile chemical transformations arises from the reactive nature of an incipient dinitrogen molecule at the terminal position. In this work, we report the synthesis and characterization of an N-heterocyclic carbene (NHC)-stabilized diazoborane-a boron-centered analog of organic azides and diazoalkanes. The diazoborane displays a strong tendency to release dinitrogen, thus serving as a borylene source, in analogy to organic azides and diazoalkanes serving as nitrene and carbene sources, respectively. Also reminiscent of diazoalkane and organic azide reactivity, the diazoborane serves as a 1,3-dipole that undergoes uncatalyzed [3+2] cycloaddition with an unactivated terminal alkyne, affording a five-membered heterocycle after a two-step rearrangement.

Activating NO-sGC crosstalk in the mouse vascular niche promotes vascular integrity and mitigates acute lung injury.

Disruption of endothelial cell (ECs) and pericytes interactions results in vascular leakage in acute lung injury (ALI). However, molecular signals mediating EC-pericyte crosstalk have not been systemically investigated, and whether targeting such crosstalk could be adopted to combat ALI remains elusive. Using comparative genome-wide EC-pericyte crosstalk analysis of healthy and LPS-challenged lungs, we discovered that crosstalk between endothelial nitric oxide and pericyte soluble guanylate cyclase (NO-sGC) is impaired in ALI. Indeed, stimulating the NO-sGC pathway promotes vascular integrity and reduces lung edema and inflammation-induced lung injury, while pericyte-specific sGC knockout abolishes this protective effect. Mechanistically, sGC activation suppresses cytoskeleton rearrangement in pericytes through inhibiting VASP-dependent F-actin formation and MRTFA/SRF-dependent de novo synthesis of genes associated with cytoskeleton rearrangement, thereby leading to the stabilization of EC-pericyte interactions. Collectively, our data demonstrate that impaired NO-sGC crosstalk in the vascular niche results in elevated vascular permeability, and pharmacological activation of this crosstalk represents a promising translational therapy for ALI.

A necroptotic-independent function of MLKL in regulating endothelial cell adhesion molecule expression.

Mixed-lineage kinase domain-like protein (MLKL) is known as the terminal executor of necroptosis. However, its function outside of necroptosis is still not clear. Herein, we demonstrate that MLKL promotes vascular inflammation by regulating the expression of adhesion molecules ICAM1, VCAM1, and E-selectin in endothelial cells (EC). MLKL deficiency suppresses the expression of these adhesion molecules, thereby reducing EC-leukocyte interaction in vitro and in vivo. Mechanistically, we show that MLKL interacts with RBM6 to promote the mRNA stability of adhesion molecules. In conclusion, this study identified a novel role of MLKL in regulating endothelial adhesion molecule expression and local EC-leukocyte interaction during acute inflammation.