# Regulation of the mechanoresponsive Neat1 and PSPC1 by substrate stiffness in TGF-β1-induced renal progenitor cell fate

## TL;DR

This study shows how the stiffness of the environment affects kidney stem cell fate through the regulation of Neat1 and PSPC1 by TGF-β1.

## Contribution

The novel contribution is linking the mechano-regulation of paraspeckle complex to TGF-β1-induced renal stem cell fate decisions.

## Key findings

- TGF-β1 induces myofibroblast or endothelial-like differentiation depending on matrix stiffness.
- PSPC1 and Neat1 are regulated by matrix stiffness and influence TGF-β1 signaling outcomes.
- PSPC1 and Neat1 respond to mechanical signals via β1-integrin-YAP and Piezo1 pathways.

## Abstract

Physical differences between acute kidney injury and chronic kidney disease, particularly in matrix stiffness, may influence mesenchymal stem cells to promote either regeneration or fibrosis; however, the underlying mechanisms remain unclear. Here, we investigate the role of paraspeckles and the long non-coding RNA Neat1 in TGF-β1-induced stem cell fate determination.

Mouse kidney progenitor cells (MKPCs) were cultured on stiff (collagen-coated dishes) and soft (type I collagen gel) matrices and treated with TGF-β1. RNA sequencing and subsequent bioinformatic analyses were performed to identify transcriptional differences between cells on stiff and soft matrices under TGF-β1 stimulation. Western-blotting and qPCR were used to quantify target proteins and RNA levels. Immunofluorescence staining and RNA fluorescence in situ hybridization were conducted to examine the subcellular localization of proteins and RNAs. Loss-of-function and gain-of-function experiments were performed using siRNA, shRNA, pharmacological inhibitors and expression vector.

We found that TGF-β1 induced MKPC differentiation into myofibroblasts on stiff matrices or endothelial-like cells on soft matrices. Matrix stiffness regulated PSPC1 and Neat1 to trigger either TGF-β1-induced transdifferentiation into myofibroblasts or angiogenesis on soft collagen gels. Stiff matrices increased the expression levels of Neat1 and PSPC1, whereas soft matrices reduced their expressions. Knockdown of PSPC1 impaired myofibroblast differentiation on stiff matrices and partially reduced angiogenesis on soft matrices. On stiff matrices, TGF-β1 markedly reduced Neat1 levels, potentially releasing PSPC1 to interact with pSmad2/3 and activate EMT-related gene expression, thereby promoting myofibroblast activation. Furthermore, we identified two mechanosensory pathways that PSPC1 and Neat1 responded to mechanical signals via β1-integrin-YAP and Piezo1 pathways.

This study links mechano-regulation of paraspeckle complex to TGF-β1-induced renal mesenchymal stem cell fate, providing insights into mechanotransduction and nuclear signaling in kidney fibrosis and regeneration.

The online version contains supplementary material available at 10.1186/s12929-025-01196-w.