Stem cell expression of CXCR4 regulates tissue composition in the vomeronasal organ.

The vomeronasal organ (VNO) detects signaling molecules that often prompt innate behaviors, such as aggression and reproduction. Vomeronasal sensory neurons, classified into apical and basal lineages based on receptor expression, have a limited lifespan and are continuously replaced from a common stem cell niche. Using a combination of single-cell RNA sequencing data, immunofluorescence staining and lineage tracing, we identified CXCR4 expression in proliferative stem cells and the basal neuronal lineage.

ACKR3 in olfactory glia cells shapes the immune defense of the olfactory mucosa.

Barrier-forming olfactory glia cells, termed sustentacular cells, play important roles for immune defense of the olfactory mucosa, for example as entry sites for SARS-CoV-2 and subsequent development of inflammation-induced smell loss. Here we demonstrate that sustentacular cells express ACKR3, a chemokine receptor that functions both as a scavenger of the chemokine CXCL12 and as an activator of alternative signaling pathways. Differential gene expression analysis of bulk RNA sequencing data obtained from WT and ACKR3 conditional knockout mice revealed upregulation of genes involved in immune defense.

GPRC5C regulates the composition of cilia in the olfactory system.

Background: Olfactory sensory neurons detect odourants via multiple long cilia that protrude from their dendritic endings. The G protein-coupled receptor GPRC5C was identified as part of the olfactory ciliary membrane proteome, but its function and localization is unknown.

Results: High-resolution confocal and electron microscopy revealed that GPRC5C is located at the base of sensory cilia in olfactory neurons, but not in primary cilia of immature neurons or stem cells.

Glia Cells Control Olfactory Neurogenesis by Fine-Tuning CXCL12.

Olfaction depends on lifelong production of sensory neurons from CXCR4 expressing neurogenic stem cells. Signaling by CXCR4 depends on the concentration of CXCL12, CXCR4's principal ligand. Here, we use several genetic models to investigate how regulation of CXCL12 in the olfactory stem cell niche adjusts neurogenesis.