In vivo genetic labeling of primary cilia in developing astrocytes.

Background: Astrocyte cilia are largely understudied due to the lack of available tools. Astrocyte research advanced with the establishment of Aldh1l1-Cre^ERT2, an inducible Cre line that specifically targets the astrocyte lineage. Here, we develop and compare genetic models that label astrocyte cilia in the developing prefrontal cortex (PFC) using Aldh1l1-Cre^ERT2 and Cre-dependent cilia reporters. We evaluate these models by testing different tamoxifen-induction protocols and quantifying the percentage of astrocytes labeled with the cilia reporters.

Results: We show that tamoxifen dosage impacts the expression of cilia reporters in astrocytes. We uncover the maximum cilia-labeling efficiency using recombined, constitutively-expressed cilia reporters.

Conclusion: The data reveal that only a subset of SOX9- positive astrocytes in the PFC possess cilia throughout development. Our work highlights the utility of Cre-Lox systems to target specific cell types and the importance of carefully validating genetic models.