The male tail of C. elegans is a complex structure composed of nine pairs of sensory rays embedded in a cuticular fan. Among the regulatory genes that pattern these structures, mab-21 is required for the specification of the ray 6 identity. mab-21 mutant males show fusion of rays 4 and 6. The Mab21 gene family is highly conserved in both vertebrate and invertebrate, it is required in neural differentiation and sensory organ development. Epistatic analysis showed that mab-21 is a downstream component of the BMP pathway to regulate ray patterning. Using C. elegans as a simple model, a complete genetic network revealing the genetic relationship of mab-21 and other genes required in this process was established....[ Read more ]

The male tail of C. elegans is a complex structure composed of nine pairs of sensory rays embedded in a cuticular fan. Among the regulatory genes that pattern these structures, mab-21 is required for the specification of the ray 6 identity. mab-21 mutant males show fusion of rays 4 and 6. The Mab21 gene family is highly conserved in both vertebrate and invertebrate, it is required in neural differentiation and sensory organ development. Epistatic analysis showed that mab-21 is a downstream component of the BMP pathway to regulate ray patterning. Using C. elegans as a simple model, a complete genetic network revealing the genetic relationship of mab-21 and other genes required in this process was established.

SIN-3, a histone deacetylase associated corepressor molecule, has long been identified as a repression mediator in transcription. The isolation of SIN-3 through a yeast two-hybrid screen as an interacting partner of MAB-21 provides the first clue of the requirement of the corepressor molecule in ray development. The developmental role of the SIN-3 corepressor complex, as well as its regulatory relationship with MAB-21, was studied in detail in this thesis. The results supported the interaction between SIN-3 corepressor and MAB-21 is important in the ray patterning.

To build upon this SIN-3-MAB-21 interaction, we further investigated the genetic relationship of mab-21 and other genes required in this process. We have identified several genes, whereby their mutants display the Mab-21-like phenotype. Mutations of these genes, egl-5, mab-18, unc-130, unc-62 and BMP pathway components, abolish the ray 6 identity. Taking advantage of the available genetic mutants and transcription reporters of these mab-21 -interacting genes, their regulatory relationship was defined. While orthologs of these genes are required in mammalian eye development, sensory ray patterning process of C. elegans serves as a simple model to uncover the genetic relationship among these genes. The finding would extend our understanding into the genetic network conserved between invertebrate and vertebrate sensory organ development.