# High-dimensional co-expression network analysis reveals persistent TRH gene expression throughout axolotl telencephalon regeneration

## TL;DR

This study identifies key genes involved in axolotl brain regeneration, highlighting the consistent role of TRH in specific brain regions.

## Contribution

The study introduces a novel integration of high-dimensional co-expression analysis and spatial transcriptomics to map regeneration-related genes in axolotl.

## Key findings

- 180 hub genes were identified across axolotl telencephalon regeneration stages.
- TRH gene showed consistent spatiotemporal expression in MSN-enriched regions.
- Findings reveal a dynamic transcriptional landscape during brain regeneration.

## Abstract

The Axolotl (Ambystoma mexicanum) offers a deep insight into brain regeneration by fully reconstructing its telencephalon post-injury, a capability that most vertebrates do not have. This study aimed to identify hub genes (highest-weighted genes) underlying this process and to map their cell location by analyzing spatiotemporal transcriptomic data using high-dimensional weighted gene co-expression network analysis, integrating protein-protein interaction networks, and cross-validating findings through literature.

We identified 180 hub genes across the regeneration timeline, including several with conserved orthologs previously reported in vertebrate regeneration models. Among these candidates, TRH (Thyrotropin-Releasing Hormone) displayed the most consistent spatiotemporal pattern, appearing repeatedly as a hub gene and localizing to MSN enriched regions at multiple stages. TRH is broadly characterized in vertebrates as a neuroendocrine peptide with roles in hormonal signaling, and MSNs are known to respond to a variety of hormonal and neuropeptidergic cues. In our dataset, this background provides additional perspective on the transcriptional configurations in which TRH appears. Other hub genes showed stage/cell specific patterns, together outlining a heterogeneous and dynamic landscape of transcriptional states detected during telencephalon regeneration.

This study provides a descriptive map of gene co-expression dynamics during axolotl telencephalon regeneration. By integrating hdWGCNA, spatial transcriptomics, and network-based context, we identify hub genes and transcriptional states associated with injury response, including a persistent TRH linked MSN state. These findings offer a foundation for future experimental studies aimed at elucidating the molecular basis of axolotl brain repair.