# Connexin 43 Modulates β‐Catenin–Dependent Transcription and Secretory Responses to Oscillatory Fluid Flow in Osteocytes

## TL;DR

This study shows that Connexin 43 in osteocytes influences β-catenin signaling and gene responses to mechanical forces, linking cell membrane activity to gene regulation.

## Contribution

The study reveals a novel physical interaction between Cx43 and β-catenin, showing how Cx43 modulates transcriptional responses to mechanical loading in osteocytes.

## Key findings

- Cx43 knockout cells showed reduced active β-catenin but increased β-catenin/TCF transcriptional activity.
- Cx43 deficiency altered flow-responsive gene expression and secretome profiles, including increased OPG and reduced PGE₂.
- Cx43 physically interacts with β-catenin, linking mechanosensing to nuclear gene regulation in osteocytes.

## Abstract

Osteocytes detect and transduce mechanical cues into biochemical signals that regulate bone remodeling. Connexin 43 (Cx43) is the predominant gap junction protein in osteocytes, but its role in β‐catenin signaling during mechanical loading remains unclear. Wild‐type (WT) and Cx43 knockout (KO) OCY454 osteocytes were subjected to oscillatory fluid flow (10 dynes/cm² 1 Hz) using the Flexcell Streamer system. β‐catenin activation was assessed by Western blot and TOPflash reporter assays. Gene expression and secreted factors were quantified by qPCR and ELISA. Co‐immunoprecipitation revealed a Cx43–β‐catenin interaction in WT cells. KO cells exhibited reduced active β‐catenin protein but paradoxically elevated β‐catenin/TCF transcriptional activity. Cx43 deficiency altered flow‐responsive expression of Rankl and Col1a1, reduced baseline Ptgs2 and Gja1, and shifted the secretome toward increased OPG and reduced PGE₂ after flow. Cx43 regulates β‐catenin signaling through physical interaction and modulation of transcriptional output, linking membrane‐level mechanosensing to nuclear gene regulation. These findings extend prior models of Cx43 as a mechanosensory scaffold by demonstrating its role in coordinating β‐catenin activation and transcriptional responses to mechanical loading in osteocytes.