Biology subjects

Anzi, S.

Publications and source records attributed to Anzi, S..

3 recordsLinked to original sources

bioRxiv2026

Lef1 is dispensable for blood-brain barrier integrity despite its dominant role in endothelial Wnt signaling

The blood-brain barrier (BBB) is a specialized vascular structure essential for CNS homeostasis, whose formation and maintenance are governed by the canonical Wnt signaling pathway. While the upstream ligands and receptors are well-characterized, the downstream transcriptional architecture remains poorly understood. Here, we investigate the functional requirement for Lef1, the most abundant Tcf/Lef transcription factor and a hallmark readout of Wnt activity in brain endothelial cells (BECs). Utilizing a conditional, endothelial-specific deletion strategy in mice, we demonstrate that loss of Lef1 during either embryonic development or adult homeostasis significantly dampens Wnt transcriptional output. Surprisingly, high-resolution molecular and functional analysis reveals that this reduction results in only minor dysregulation of the BBB-specific gene program and is insufficient to trigger barrier breakdown. Our results establish that Lef1 is not an obligatory effector of the Wnt-dependent BBB maintenance program. These findings suggest a resilient transcriptional framework where redundant Tcf/Lef family members or alternative regulatory circuits preserve CNS microvasculature function, providing new insights into the genetic robustness of the blood-brain barrier. Research HighlightsO_LILef1 is the predominant Tcf/Lef transcription factor in the brain endothelium and a hallmark of vascular Wnt signaling. C_LIO_LIEndothelial-specific Lef1 deletion significantly attenuates Wnt transcriptional output during both CNS vascular development and adult homeostasis. C_LIO_LILoss of Lef1 causes only minor perturbations in the BBB-specific gene program, rather than a global loss of endothelial identity. C_LIO_LIStructural and functional BBB integrity is preserved in the absence of Lef1, revealing a high degree of vascular resilience. C_LIO_LIThe findings demonstrate that Lef1 is not an obligatory effector for the maintenance of the specialized CNS microvasculature. C_LI

neuroscience↗

bioRxiv2022

Unique features of the arterial Blood-Brain Barrier

CNS vasculature differs from vascular networks of peripheral organs by its ability to tightly control selective material exchange across capillary barriers. Capillary permeability is mostly defined by unique cellular components of the endothelium. While capillaries are extensively investigated, the barrier properties of larger vessels are understudied. Here, we investigate barrier properties of CNS arterial walls. Using tracer challenges and various imaging modalities, we discovered that at the mouse cortex, the arterial barrier does not reside at the classical level of the endothelium. The arterial walls unique permeability acts bi-directionally; CSF substances travel along the glymphatic path and can penetrate from the peri-vascular space through arteriolar walls towards the lumen. We found that caveolae vesicles in arteriole endothelial and smooth-muscle cells are functional transcytosis machinery components, and that a similar mechanism is evident in the human brain. Our discoveries highlight vascular heterogeneity investigations as a potent approach to uncover new barrier mechanisms.

neuroscience↗

bioRxiv2021

Nano-scale Architecture of Blood-Brain Barrier Tight-Junctions

Tight junctions (TJs) between blood-brain barrier (BBB) endothelial cells construct a robust physical barrier, whose damage underlies BBB dysfunctions related to several neurodegenerative diseases. What makes these highly specialized BBB-TJs extremely restrictive remains unknown. Here, we use super-resolution microscopy (dSTORM) to uncover new structural and functional properties of BBB TJs. Focusing on three major components, Nano-scale resolution revealed sparse (occludin) vs. clustered (ZO1/claudin-5) molecular architecture. Developmentally, permeable TJs become first restrictive to large molecules, and only later to small molecules, with claudin-5 proteins arrangement compacting during this maturation process. Mechanistically, we reveal that ZO1 clustering is independent of claudin-5 in-vivo. In contrast to accepted knowledge, we found that in the developmental context, total levels of claudin-5 inversely correlate with TJ functionality. Our super-resolution studies provide a unique perspective of BBB TJs and open new directions for understanding TJ functionality in biological barriers, ultimately enabling restoration in disease or modulation for drug delivery.

cell biology↗