Piezo1 mediated calcium-calcineurin signaling pathway regulates gastrointestinal smooth muscle cell phenotype in a stiffness dependent manner
Authors: Joshi Vikram , Knutson Kaitlyn , Laible Emma , Niloy Sayeman Islam , Liu Yuanhang , Farrugia Gianrico , Cipriani Gianluca 
Published: May 2024

Background: Gastrointestinal (GI) disorders like chronic constipation are more prevalent with aging. Aging GI tract becomes stiffer and exhibits delayed GI transit. Smooth muscle cells (SMCs) are involved in controlling GI transit and show reduced contractility with age. Piezo1 is a mechanically activated ion channel that responds to membrane tension by opening its pore to allow flow of ions such as calcium (Ca2+) and regulates various cellular processes through Ca2+-calcineurin signaling pathway. We wondered GI stiffness changes might control SMC contractile to non-contractile phenotype through Piezo1. Objective: To determine how substrate stiffness regulates GI SMC contractile phenotype through Piezo1. Hypothesis: SMC Piezo1 senses GI tissue stiffness changes and alters SMC phenotype. Methods: Pathway analysis on human colon single cell sequencing data was performed using Gene Set Enrichment Analysis (GSEA) pre-ranked module with publicly available gene-sets from Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Immortalized human jejunal SMCs (HuSMCs) and freshly dissociated SMCs from control (CTRL, Myh11-creERT2) and SMC specific Piezo1 knockout [Myh11-creERT2xPiezo1 Flox (Piezo1-KO)] mouse colons (primary SMCs) were cultured on soft (1kPa) and stiff (50kPa) substrates to model age-dependent shifts in intestinal stiffness for 48 hours either in the presence/absence of Piezo1 siRNA, Piezo1 agonist (Yoda1, 1μM), and calcineurin blocker (Cyclosporin A, CsA, 1μM) and used for Ca2+ imaging, RT-qPCR and immunostaining. Results: GSEA showed Piezo1+ve SMCs were significantly enriched in pathways involved in the regulation of Ca2+ signaling compared to Piezo1−ve SMCs (p<0.05). HuSMCs and primary SMCs showed increased Piezo1 expression (HuSMCs:1.1±0.2-fold, n=8, p<0.05; primary SMCs:2.1±0.1-fold, n=3, p<0.05) and cytoplasmic Ca2+ (3.6-fold, n=10, p<0.05) in response to Yoda1 on stiff substrates compared to soft. HuSMCs on stiff substrate showed decreased expression of contractile SMC markers smoothelin ( SMTN:0.7±0.2-fold, n=7, p<0.05) and transgelin ( TAGLN:0.6±0.1-fold, n=7, p<0.05) which was rescued by Piezo1 siRNA treatment ( SMTN:1.2±0.1-fold, n=2-7, p<0.05; TAGLN:1.15±0.02-fold, n=2-7, p<0.05) (Piezo1 is necessary). Stimulation by Yoda1 of HuSMCs on the soft substrate resulted in decreased expression of SMTN (0.7±0.3-fold, n=2-7, p<0.05) and TAGLN (0.7±0.1-fold, n=2-7, p<0.05) (Piezo1 is suffcient). CTRL primary SMCs on stiff substrate showed decreased expression of Smtn (0.4±0.1-fold, n=3, p<0.05) and Tagln (0.3±0.2-fold, n=3, p<0.05) compared to SMCs on soft substrate which was reversed when SMCs from Piezo1-KO mice were cultured on these substrates ( Smtn:1.8±0.5-fold, n=3, p<0.05; Tagln:2.4±0.07-fold, n=3, p<0.05). Treatment of CsA in HuSMCs cultured on stiff substrate also rescued from loss of SMTN (1.3±0.1-fold, n=3, p<0.05) and TAGLN (1.7±0.3-fold, n=3, p<0.05) expression and prevented nuclear factor of activated T cells (NFAT) nuclear translocation. Summary and Conclusion: GI SMC Piezo1 senses stiffness changes and regulates SMC phenotype through Ca2+-calcineurin signaling pathway. Targeting Piezo1 might be protective from age induced reduced GI SMC contractility. NIH DK052766, DK123549. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.