The CATP-8/P5A-type ATPase functions in multiple pathways during neuronal patterning
Authors: Tang Leo T.H. , Trivedi Meera , Freund Jenna , Salazar Christopher J. , Ramirez-Suarez Nelson J. , Lee Garrett , Rahman Maisha , Wang Yu , Grant Barth D. , Bülow Hannes E. 
Published: March 2021

ABSTRACTThe assembly of neuronal circuits involves the migrations of neurons from their place of birth to their final location in the nervous system, as well as the coordinated growth and patterning of axons and dendrites. In screens for genes required for patterning of the nervous system, we identified thecatp-8/P5A-ATPaseas an important regulator of neural patterning. P5A-ATPases are part of the P-type ATPases, a family of proteins known to serve a conserved function as transporters of ions, lipids and polyamines in unicellular eukaryotes, plants, and humans. While the function of many P-type ATPases is relatively well understood, the function of P5A-ATPases in metazoans remained elusive. We show here, that theCaenorhabditis elegansorthologcatp-8/P5A-ATPaseis required for specific aspects of nervous system development. Specifically, thecatp-8/P5A-ATPaseserves functions in shaping the elaborately sculpted dendritic trees of somatosensory PVD neurons. Moreover,catp-8/P5A-ATPaseis required for axonal guidance and repulsion at the midline, as well as embryonic and postembryonic neuronal migrations. Interestingly, not all axons at the midline requirecatp-8/P5A-ATPase, although the axons run in the same fascicles and navigate the same space. Similarly, not all neuronal migrations requirecatp-8/P5A-ATPase. A CATP-8/P5A-ATPasereporter is localized to the ER in most if not all tissues andcatp-8/P5A-ATPasecan function both cell-autonomously and non-autonomously to regulate neuronal development. Genetic analyses establish thatcatp-8/P5A-ATPasecan function in multiple pathways, including the Menorin pathway, previously shown to control dendritic patterning in PVD, and Wnt signaling, which functions to control neuronal migrations. Lastly, we show thatcatp-8/P5A-ATPaseis required for localizing select transmembrane proteins necessary for dendrite morphogenesis. Collectively, our studies suggest thatcatp-8/P5A-ATPaseserves diverse, yet specific roles in different genetic pathways, and may be involved in the regulation or localization of transmembrane proteins to specific subcellular compartments.AUTHOR SUMMARYP-type ATPases are a large family of transporters that are conserved from unicellular eukaryotes and plants to metazoans. Structurally and functionally, they fall into five subfamilies, P1 to P5, of which the latter is further divided into P5A and P5B-type ATPases. Unlike for other P-type ATPases, no mutant phenotypes for the P5A-type ATPases have been described in metazoans. Here, we show that thecatp-8/P5A-ATPasein the nematodeCaenorhabditis elegansis involved in multiple aspects of neuronal patterning, including neuronal migrations as well as axon guidance and dendrite patterning. A functional fluorescent reporter fusion shows the CATP-8/P5A-ATPase is expressed in most, if not all, tissues in the endoplasmic reticulum andcatp-8can function both in neurons and surrounding tissues from where it orchestrates neuronal development. Genetically,catp-8acts in multiple pathways during these processes, including the Wnt signaling and the Menorin pathway. Imaging studies suggest that thecatp-8/P5A-ATPaseis necessary for proper localization of cell-surface transmembrane molecules to dendrites of sensory neurons, but likely not for their trafficking. In summary, we propose that CATP-8/P5A-ATPase serves a function in the ER during development of select neurons, by localizing certain transmembrane, and possibly, secreted proteins