Investigation of the role of the stiffness-response gene in fate switching during neurogenesis

초록

The mechanical properties of the extracellular microenvironment, including its stiffness, play a critical role in stem cell differentiation. Although previous studies have shown that the developing brain exhibits spatiotemporal diversity in stiffness (Iwashita et al., Development, 2014), it remains unclear how neural stem cells sense the stiffness of their microenvironment and change their fate toward specific neural lineages at molecular resolution in vivo. To address this question, we performed a reconstitution assay combined with RNA-Seq using brain stiffness-mimicking gels established by our group from tilapia skin collagen (Iwashita et al., Scientific Reports, 2019). Neural stem cells derived from mouse embryonic brains were cultured on "Soft" and "Hard" gels, mimicking local tissue stiffness in the developing brain. Through bioinformatics analysis, we identified the ER stress pathway gene that was differentially expressed between "Soft" and "Hard" conditions in the differentiated neurons derived from neural stem cells. To investigate its functions, we analyzed the expression pattern of the neural-specific markers Ctip2 (expressed in layer V) and Satb2 (expressed in layer II/III). Gain-of-function and loss-of-function analysis in vivo revealed a shift in the expression pattern of Ctip2 and Satb2 during neural differentiation. ER stress pathway inhibitor analysis in vitro induced the differences in the expression pattern of Ctip2 and Satb2 as similar as in vivo. Our results suggest that the ER stress pathway responds to brain stiffness during brain development.