Swoboda, P. | Search bioRxiv

bioRxiv2021

The C. elegans DAF-19M module: a shift from general ciliogenesis to ciliary and behavioral specialization

In animals, cilia are important for the interaction with environments and the proper function of tissues and organs. Understanding the distinctive identities of each type of ciliated cell is essential for therapeutic solutions for ciliopathies, complex disorders with impairments of various organs caused by defective cilia development and function. Here, we report a regulatory module consisting of a cascade of transcription factors and their target genes that confer the cell type-specific ciliary identities on the IL2 ciliated neurons in C. elegans. We found that DAF-19M, isoform of the sole C. elegans RFX transcription factor DAF-19, through X-box promoter motif variants, heads a regulatory module in IL2 neurons, comprising the core target genes klp-6 (kinesin), osm-9 (TRP channel), and cwp-4 (novel); under the overall control of terminal selector proteins UNC-86 and CFI-1. Considering the conservation of this DAF-19M module in IL2 neurons for nictation, a dauer larva-specific behavior, and in male-specific neurons for mating behavior, we propose the existence of an evolutionarily adaptable, hard-wired genetic module for distinct behaviors that share the feature "recognizing the environment."

molecular biology↗

bioRxiv2020

Differentiation of ciliated human midbrain-derived LUHMES neurons

Many human cell types are ciliated, including neural progenitors and differentiated neurons. Ciliopathies are characterized by defective cilia and comprise various disease states, including brain phenotypes, where the underlying biological pathways are largely unknown. Our understanding of neuronal cilia is rudimentary and an easy-to-maintain, ciliated human neuronal cell model is missing. LUHMES is a ciliated neuronal cell line derived from human fetal mesencephalon. LUHMES cells can easily be maintained and differentiated into mature, functional neurons within one week. They have a single primary cilium as proliferating progenitor cells and as post-mitotic, differentiating neurons. These developmental stages are completely separable within one day of culture condition change. The Sonic Hedgehog (SHH) signaling pathway is active in differentiating LUHMES neurons. RNA-seq time course analyses reveal molecular pathways and gene-regulatory networks critical for ciliogenesis and axon outgrowth at the interface between progenitor cell proliferation, polarization and neuronal differentiation. Gene expression dynamics of cultured LUHMES neurons faithfully mimic the corresponding in vivo dynamics of human fetal midbrain. In LUHMES, neuronal cilia biology can be investigated along a complete timeline: from proliferation through differentiation to mature neurons. Summary StatementWith LUHMES, a ciliated human neuronal cell model, the underlying "neurobiology" of cilia and ciliopathies can be investigated along a complete time line: from proliferation through differentiation to mature neurons.

neuroscience↗