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Chung, H. M.

Publications and source records attributed to Chung, H. M..

2 recordsLinked to original sources

Interpretable variational encoding of genotypes identifiescomprehensive clonality and lineages in single cells geometrically

Clone assignment in single-cell genomics remains a challenge due to its diverse mutation macrostructures and many missing signals. Existing statistical methods, for the sake of numerical convergence, pose strong constraints on the form of predicted mutation patterns, so they easily identify sub-optimally fitted clones that overlook weak and rare mutations. To solve this problem, we developed SNPmanifold, a Python package that learns flexible mutation patterns using a shallow binomial variational autoencoder. The latent space of SNPmanifold can effectively represent and visualize complex mutations of SNPs (single-nucleotide polymorphisms) in the form of geometrical manifolds. Based on nuclear or mitochondrial SNPs, we demonstrated that SNPmanifold can effectively identify a large number of multiplexed donors of origin (k = 18) that all existing unsupervised methods fail and lineages of somatic clones with promising biological interpretation. Therefore, SNPmanifold can reveal insights into single-cell SNPs more comprehensively than other existing methods, especially in complex datasets.

genomics↗

Frem1 activity regulated by Sonic Hedgehog signaling in the cranial neural crest mesenchyme guides midfacial morphogenesis

The Frem/Fras family of extracellular matrix proteins has been linked to human face shape variation and malformation, but little is known about their regulation and biological roles in facial development. During midfacial morphogenesis in mice, we observed Frem1 expression in the embryonic growth centers that form the median upper lip, nose, and palate. Expansive spatial gradients of Frem1 expression in the cranial neural crest cell (cNCC) mesenchyme of these tissues suggested transcriptional regulation by a secreted morphogen. Accordingly, Frem1 expression paralleled that of the conserved Sonic Hedgehog (Shh) target gene Gli1 in the cNCC mesenchyme. Suggesting direct transcriptional regulation by Shh signaling, we found that Frem1 expression is induced by SHH ligand stimulation or downstream pathway activation in cNCCs and observed GLI transcription factor binding at the Frem1 transcriptional start site during midfacial morphogenesis. Shh pathway antagonism reduced Frem1 expression during pathogenesis of midfacial hypoplasia, and FREM1 was sufficient to induce cNCC proliferation in a concentration-dependent manner. These findings provide novel insight into the mechanism by which the Shh pathway drives midfacial morphogenesis and reveal a functional role for Frem1 in cNCC biology that establishes the developmental basis for FREM1-associated face shape variation and malformation.

developmental biology↗