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Biology subjects

McGrath, P. S.

Publications and source records attributed to McGrath, P. S..

2 recordsLinked to original sources

Nuclei sense complex tissue shape and direct intestinal stem cell fate

Tissue architecture and function are influenced by mechanical cues. Yet, how cell nuclei sense forces within 3D tissues and dictate differentiation remains unknown as prior studies focused on isolated mesenchymal cells, which fail to fully predict tissue-level mechanical properties. We fill this knowledge gap utilizing live reporters and material-based organoid models. We posit the nucleus as an active mechanosensor of tissue shape, with levels of the nuclear scaffolding protein lamin-A varying across intestinal stem cell differentiation trajectory. Elevated forces on differentiated Paneth cell nuclei, in both organoids and tissue explants, increase lamin-A and nuclear wrinkling. Enhancing nuclear mechanotransduction primes cell differentiation, in otherwise stem promoting conditions, revealing that nuclear mechanics can direct stem cell fate. By engineering spatiotemporally controlled de novo tissue curvature with photo-degradable hydrogels, we direct spatially patterned lamin-A levels across mouse and human organoids of healthy and diseased origin, uncovering conserved nuclear mechanosensing pathway in epithelial tissues.

bioengineering↗

Human NKX2.2 influences islet endocrine cell fate choices through regulation of WNT pathway genes

Transcriptional regulation is a key central mechanism of cell fate determination in developing tissues. The homeobox transcription factor NKX2.2 is an essential regulator of mouse and human pancreatic endocrine development, however its precise molecular role in a human system has not been previously investigated. In this study we generated NKX2.2 null (NKX2.2KO) human embryonic stem cell (hESC) lines using CRISPR/Cas9 technologies and differentiated them towards a pancreatic {beta} cell fate using a stem cell-derived {beta} cell differentiation protocol. Functional and transcriptomic analyses of the hESC-derived pancreatic endocrine cells lacking NKX2.2 revealed similarities and differences compared to the molecular functions of NKX2.2 in mice. In the absence of NKX2.2, the {beta} cell differentiations result in reduced numbers of insulin-producing cells, and the differentiations become skewed towards polyhormonal fates, including cells co-expressing insulin, ghrelin and somatostatin. Deletion of NKX2.2 also eliminates the off-target formation of enterochromaffin cells. Single cell transcriptome analysis of the early endocrine cell population revealed a marked disruption of metabolic pathways that was confirmed by comparative metabolite tracing, providing novel insights into the regulation of early endocrine lineage decisions. Furthermore, NKX2.2 directly regulates several genes in the WNT signaling pathway, suggesting this is a key molecular mechanism through which NKX2.2 regulates these islet cell fate decisions in the human system.

developmental biology↗