Patterning of sexually dimorphic neurogenesis in the Caenorhabditis elegans ventral cord by Hox and TALE homeodomain transcription factors

• Published in: Developmental dynamics 2014-01, Vol.243 (1), p.159-171
• Main Authors: Kalis, Andrea K., Kissiov, Djem U., Kolenbrander, Emily S., Palchick, Zachary, Raghavan, Shraddha, Tetreault, Breanna J., Williams, Erin, Loer, Curtis M., Wolff, Jennifer Ross
• Format: Article
• Language: English
• Subjects: Animals; Body Patterning - genetics; Body Patterning - physiology; C. elegans; Caenorhabditis elegans; Caenorhabditis elegans - embryology; Caenorhabditis elegans - metabolism; Caenorhabditis elegans Proteins - genetics; Caenorhabditis elegans Proteins - metabolism; Female; Homeodomain Proteins - genetics; Homeodomain Proteins - metabolism; Hox genes; Male; male‐specific neurons; neurogenesis; Neurons - metabolism; sexual dimorphism; TALE homeodomain proteins; Transcription Factors - genetics; Transcription Factors - metabolism; ventral cord neurons
• ISSN: 1058-8388; 1097-0177
• DOI: 10.1002/dvdy.24064

Background: Reproduction in animals requires development of distinct neurons in each sex. In C. elegans, most ventral cord neurons (VCNs) are present in both sexes, with the exception of six hermaphrodite‐specific neurons (VCs) and nine pairs of male‐specific neurons (CAs and CPs) that arise from analogous precursor cells. How are the activities of sexual regulators and mediators of neuronal survival, division, and fate coordinated to generate sex‐specificity in VCNs? Results: To address this, we have developed a toolkit of VCN markers that allows us to examine sex‐specific neurogenesis, asymmetric fates of daughters of a neuroblast division, and regional specification on the anteroposterior axis. Here, we describe the roles of the Hox transcription factors LIN‐39 and MAB‐5 in promoting survival, differentiation, and regionalization of VCNs. We also find that the TALE class homeodomain proteins CEH‐20 and UNC‐62 contribute to specification of neurotransmitter fate in males. Furthermore, we identify that VCN sex is determined during the L1 larval stage. Conclusions: These findings, combined with future analyses made possible by the suite of VCN markers described here, will elucidate how Hox‐mediated cell fate decisions and sex determination intersect to influence development of neuronal sex differences. Developmental Dynamics 243:159–171, 2014. © 2013 Wiley Periodicals, Inc. Key Findings C. elegans male and hermaphrodite ventral nerve cords are sexually distinct with sex determination occurring during the first larval stage. Hox genes lin‐39 and mab‐5 influence multiple events in neurogenesis and function in partially overlapping regions in the ventral nerve cord. TALE homeodomain genes ceh‐20 and unc‐62 are required with lin‐39 to specify serotonergic fate in male ventral cord neurons. unc‐3 prevents inappropriate serotonergic specification in both males and hermaphrodites.