Biology subjects

Kukreja, K.

Publications and source records attributed to Kukreja, K..

4 recordsLinked to original sources

bioRxiv2025

A single-cell transcriptomic atlas of inner ear morphogenesis in zebrafish

The inner ear constitutes different cell types next to one another: the sensory patches whose hair cells synapse with neurons, the thin channels of three semicircular canals whose perpendicular organization enables detection of directional head rotation, and the endolymphatic duct and sac whose conditional epithelial barrier relieves excess pressure and promotes fluid pressure homeostasis. How the ears component cell states are established during development has remained unknown. We use single-cell RNA sequencing to distinguish cell states within the developing ear with wild-type zebrafish embryos and lmx1bb mutants that exhibit defects in canal and sac morphogenesis. We identify the earliest marker for the semicircular canal-genesis zone (ccn1l1), unexpected genes in the endolymphatic sac that suggest a role for tissue contraction in its function (smtnb), parallel gene sets for sensory patches in the neuromast and ear, and a conserved role for cell-cycle pausing (cdkn1bb expression in the canals and sac as previously observed in the developing mouse ear). This atlas provides the most comprehensive transcriptional profiling of the developing inner ear, identifying new molecular leads to understand ear morphogenesis. Summary statementSingle-cell transcriptomic analysis of developing wild-type and lmx1bb mutant zebrafish reveals cell-states and effectors that distinguish the inner ears sensory patches, semicircular canals, endolymphatic duct and sac, and periotic mesenchyme.

developmental biology↗

bioRxiv2023

Global decoupling of cell differentiation from cell division in early embryo development

As tissues develop, cells divide and differentiate concurrently. Conflicting evidence shows that cell division is either dispensable or required for formation of cell types. To determine the role of cell division in differentiation, we arrested the cell cycle in zebrafish embryos using two independent approaches and profiled them at single-cell resolution. We show that cell division is dispensable for differentiation of all embryonic tissues during initial cell type differentiation from early gastrulation to the end of segmentation. In the absence of cell division, differentiation slows down in some cell types, and cells exhibit global stress responses. While differentiation is robust to blocking cell division, the proportions of cells across cell states are not. This work simplifies our understanding of the role of cell division in development and showcases the utility of combining embryo-wide perturbations with single-cell RNA sequencing to uncover the role of common biological processes across multiple tissues.

developmental biology↗

bioRxiv2022

A map of signaling responses in the human airway epithelium

Receptor-mediated signaling plays a central role in tissue regeneration, and it is dysregulated in disease. Here, we build a signaling-response map for a model regenerative human tissue: the airway epithelium. We analyzed the effect of 17 receptor-mediated signaling pathways on organotypic cultures to determine changes in abundance and phenotype of all epithelial cell types. This map recapitulates the gamut of known airway epithelial signaling responses to these pathways. It defines convergent states induced by multiple ligands and diverse, ligand-specific responses in basal-cell and secretory-cell metaplasia. We show that loss of canonical differentiation induced by multiple pathways is associated with cell cycle arrest, but that arrest is not sufficient to block differentiation. Using the signaling-response map, we show that a TGFB1-mediated response underlies specific aberrant cells found in multiple lung diseases and identify interferon responses in COVID-19 patient samples. Thus, we offer a framework enabling systematic evaluation of tissue signaling responses.

systems biology↗

bioRxiv2021

Genome-wide functional screen of 3'UTR variants uncovers causal variants for human disease and evolution

3 untranslated region (3UTR) variants are strongly associated with human traits and diseases, yet few have been causally identified. We developed the Massively Parallel Reporter Assay for 3UTRs (MPRAu) to sensitively assay 12,173 3UTR variants. We applied MPRAu to six human cell lines, focusing on genetic variants associated with genome-wide association studies (GWAS) and human evolutionary adaptation. MPRAu expands our understanding of 3UTR function, suggesting that low-complexity sequences predominately explain 3UTR regulatory activity. We adapt MPRAu to uncover diverse molecular mechanisms at base-pair resolution, including an AU-rich element of LEPR linked to potential metabolic evolutionary adaptations in East Asians. We nominate hundreds of 3UTR causal variants with genetically fine-mapped phenotype associations. Using endogenous allelic replacements, we characterize one variant that disrupts a miRNA site regulating the viral defense gene TRIM14, and one that alters PILRB abundance, nominating a causal variant underlying transcriptional changes in age-related macular degeneration.

genetics↗