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Biology subjects

Singh, P. N. P.

Publications and source records attributed to Singh, P. N. P..

3 recordsLinked to original sources

Niche-driven phenotypic plasticity and cis-regulatory dynamics of a revised model for intestinal secretory differentiation

HIGHLIGHTSO_LIDelineation of chromatin and mRNA dynamics of intestinal secretory differentiation C_LIO_LIPaneth cells have few unique enhancers and share mRNAs and TFs with goblet cells C_LIO_LIUnlike other secretory derivatives, goblet and Paneth cells are not specified per se C_LIO_LINiche factors, especially BMP signaling, define goblet and Paneth phenotypes C_LI Enterocytes and four secretory cell types derive from stem cells located in intestinal crypts. Whereas secretory goblet and Paneth cells have long been considered distinct, we find high overlap in their transcripts and sites of accessible chromatin, in marked contrast to those of sibling enteroendocrine or tuft cells. Mouse and human goblet and Paneth cells express extraordinary fractions of selective antimicrobial genes, reflecting specific and variable gene responses to local niche signals. Wnt signaling retains few ATOH1+ secretory daughters in crypt bottoms, where an absence of BMP signaling potently induces Paneth features; those that move away from crypt bottoms acquire classic goblet properties. These post-mitotic cellular phenotypes and their underlying accessible cis-elements interconvert readily. Thus, goblet and Paneth properties represent alternative manifestations of a single versatile signal-responsive secretory cell. These findings reveal exquisite niche-dependent cell plasticity and the cis-regulatory dynamics of an updated unitarian model of the intestinal epithelial lineage.

cell biology↗

Transcription factor dynamics, oscillation, and functions in human enteroendocrine cell differentiation

Enteroendocrine cells (EECs), which secrete serotonin (enterochromaffin cells, EC) or a dominant peptide hormone, serve vital physiologic functions. As with any adult human lineage, the basis for terminal cell diversity remains obscure. We replicated human EEC differentiation in vitro, mapped transcriptional and chromatin dynamics that culminate in discrete cell types, and studied abundant EEC precursors expressing selected transcription factors (TFs) and gene programs. Before expressing the pre-terminal factor NEUROD1, non-replicating precursors oscillated between epigenetically similar but transcriptionally distinct ASCL1+ and HES6hi cell states. Loss of either factor substantially accelerated EEC differentiation and disrupted EEC individuality; ASCL1 or NEUROD1 deficiency had opposing consequences on EC and hormone-producing cell features. Expressed late in EEC differentiation, the latter TFs mainly bind cis-elements that are accessible in undifferentiated stem cells and tailor the subsequent expression of TF combinations that specify EEC types. Thus, TF oscillations retard EEC maturation to enable accurate EEC diversification.

molecular biology↗

A MTA2-SATB2 chromatin complex restrains colonic plasticity toward small intestine by retaining HNF4A at colonic chromatin

Plasticity between cell lineages is a fundamental but poorly understood property of regenerative tissues. In the gut tube, small intestine absorbs nutrients whereas colon absorbs electrolytes. In a striking display of inherent plasticity, adult colonic mucosa lacking the chromatin factor SATB2 is converted to small intestine. Using proteomics and CRISPR-Cas9 screen, we identified MTA2 as a crucial component of the molecular machinery that, together with SATB2, restrain colonic plasticity. MTA2 loss in adult mouse colon activated lipid absorptive genes and functional lipid uptake. Mechanistically, MTA2 co-binds with HNF4A, an activating pan-intestine transcription factor (TF), on colonic chromatin. MTA2 loss leads to HNF4A release from colonic and gain on small intestinal chromatin. SATB2 similarly restrains colonic plasticity through a HNF4A-dependent mechanism. Our study provides a generalizable model of lineage plasticity in which broadly-expressed TFs are retained on tissue-specific enhancers to maintain cell identity and prevent activation of alternative lineages; their release unleashes plasticity.

developmental biology↗