The Caenorhabditis elegans aristaless orthologue, alr-1, is required for maintaining the functional and structural integrity of the amphid sensory organs

The homeobox-containing aristaless-related protein ARX has been directly linked to the development of a number of human disorders involving mental retardation and epilepsy and clearly plays a critical role in development of the vertebrate central nervous system. In this work, we investigate the role of ALR-1, the Caenorhabditis elegans aristaless orthologue, in amphid sensory function. Our studies indicate that ALR-1 is required for maintenance of the amphid organ structure throughout larval development. Mutant analysis indicates a progressive loss in the amphid neurons' ability to fill with lipophilic dyes as well as a declining chemotactic response. The degeneration in amphid function corresponds with a failure of the glial-like amphid socket cell to maintain its specific cell shape and cell-cell contacts. Consistent with ALR-1 expression within the amphid socket cell, our results indicate a cell autonomous role for ALR-1 in maintaining cell shape. Furthermore, we demonstrate a role for ALR-1 in the proper morphogenesis of the anterior hypodermis. Genetic interaction tests also suggest that ALR-1 may function cooperatively with the cell adhesion processes in maintaining the amphid sensory organs.