# Physical crowding in 3D niche regulates neural stem cell differentiation via Cx43-mediated gap junction communication

## TL;DR

This study shows that physical crowding in 3D environments helps neural stem cells become neurons by increasing Cx43 gap junction communication.

## Contribution

The study reveals that 3D crowding uniquely activates Cx43-mediated gap junctions to regulate stem cell differentiation.

## Key findings

- 3D crowding promotes neuronal differentiation through Cx43 gap junctions.
- Cx43 inhibition reduces 3D crowding-induced differentiation.
- Intercellular signaling via Cx43 is essential for 3D niche regulation.

## Abstract

Neural stem cells (NSCs) maintain central nervous system (CNS) homeostasis through self-renewal and differentiation into neurons and glia. Although physical crowding shapes the NSC niche during CNS development, its role in fate determination remains poorly understood. We investigated how NSC crowding influences intercellular junctions and lineage specification in 2D and 3D environments. While crowding promotes neuronal differentiation in both environments, robust junctional remodeling occurred only in 3D. Specifically, 3D crowding uniquely upregulated connexin 43 (Cx43)-mediated gap-junction assembly. Pharmacological Cx43 inhibition selectively attenuated 3D crowding-induced neuronal differentiation, demonstrating that gap-junction signaling is essential for fate determination in 3D. These findings highlight that the regulatory influence of NSC crowding is dimension-dependent and mediated through Cx43 gap-junction communication. By elucidating how biophysical context integrates with intercellular signaling to guide NSC behavior, this study offers mechanistic insights into stem cell biology and informs biomimetic 3D culture systems and regenerative strategies for neural tissue repair.

•Cell crowding promotes NSC differentiation through dimension-specific mechanisms•3D crowding uniquely upregulates Cx43-mediated gap junction•Gap junction is specifically required for 3D crowding-induced NSC differentiation

Cell crowding promotes NSC differentiation through dimension-specific mechanisms

3D crowding uniquely upregulates Cx43-mediated gap junction

Gap junction is specifically required for 3D crowding-induced NSC differentiation

Cellular neuroscience; Stem cells research