MAB-5/Hox regulates the Q neuroblast transcriptome, including cwn-1/Wnt, to mediate posterior migration in Caenorhabditis elegans

• Published in: Genetics (Austin) 2024-06, Vol.227 (2)
• Main Authors: Paolillo, Vitoria K, Ochs, Matthew E, Lundquist, Erik A
• Format: Article
• Language: English
• Subjects: Animals; Caenorhabditis elegans - genetics; Caenorhabditis elegans - metabolism; Caenorhabditis elegans Proteins - genetics; Caenorhabditis elegans Proteins - metabolism; Cell Movement; Gene Expression Regulation, Developmental; Homeodomain Proteins; Neural Stem Cells - cytology; Neural Stem Cells - metabolism; Neurogenesis; Transcription Factors - genetics; Transcription Factors - metabolism; Transcriptome; Wnt Proteins - genetics; Wnt Proteins - metabolism; Wnt Signaling Pathway
• ISSN: 1943-2631; 1943-2631
• DOI: 10.1093/genetics/iyae045

Neurogenesis involves the precisely coordinated action of genetic programs controlling large-scale neuronal fate specification down to terminal events of neuronal differentiation. The Q neuroblasts in Caenorhabditis elegans, QL on the left and QR on the right, divide, differentiate, and migrate in a similar pattern to produce three neurons each. However, QL on the left migrates posteriorly, and QR on the right migrates anteriorly. The MAB-5/Hox transcription factor is necessary and sufficient for posterior Q lineage migration and is normally expressed only in the QL lineage. To define genes controlled by MAB-5 in the Q cells, fluorescence-activated cell sorting was utilized to isolate populations of Q cells at a time in early L1 larvae when MAB-5 first becomes active. Sorted Q cells from wild-type, mab-5 loss-of-function (lof), and mab-5 gain-of-function (gof) mutants were subject to RNA-seq and differential expression analysis. Genes enriched in Q cells included those involved in cell division, DNA replication, and DNA repair, consist with the neuroblast stem cell identity of the Q cells at this stage. Genes affected by mab-5 included those involved in neurogenesis, neural development, and interaction with the extracellular matrix. cwn-1, which encodes a Wnt signaling molecule, showed a paired response to mab-5 in the Q cells: cwn-1 expression was reduced in mab-5(lof) and increased in mab-5(gof), suggesting that MAB-5 is required for cwn-1 expression in Q cells. MAB-5 is required to prevent anterior migration of the Q lineage while it transcriptionally reprograms the Q lineage for posterior migration. Functional genetic analysis revealed that CWN-1 is required downstream of MAB-5 to inhibit anterior migration of the QL lineage, likely in parallel to EGL-20/Wnt in a noncanonical Wnt pathway. In sum, work here describes a Q cell transcriptome, and a set of genes regulated by MAB-5 in the QL lineage. One of these genes, cwn-1, acts downstream of mab-5 in QL migration, indicating that this gene set includes other genes utilized by MAB-5 to facilitate posterior neuroblast migration.