The bromodomain protein LIN-49 and trithorax-related protein LIN-59 affectdevelopment and gene expression in Caenorhabditis elegans

We have molecularly characterized the lin-49 and lin-59 genes in C. elegans , and found their products are related to Drosophila trithorax group (trx-G ) proteins and other proteins implicated in chromatin remodelling. LIN-49 i s structurally most similar to the human bromodomain protein BR140, and LIN -59 is most similar to the Drosophila trx-G protein ASH1, In C. elegans, li n-49 and lin-59 are required for the normal development of the mating struc tures of the adult male tail, for the normal morphology and function of hin dgut (rectum) cells in both males and hermaphrodites and for the maintenanc e of structural integrity in the hindgut and egg-laying system in adults. E xpression of the Hox genes egl-5 and mab-5 is reduced in lin-49 and lin-59 mutants, suggesting lin-49 and lin-59 regulate HOM-C gene expression in C, elegans as the trx-G genes do in Drosophila, lin-49 and lin-59 transgenes a re expressed widely throughout C, elegans animals. Thus, in contrast to the C, elegans Polycomb group (Pc-G)-related genes mes-2 and mes-6 that functi on primarily in the germline, we propose lin-49 and lin-59 function in soma tic development similar to the Drosophila trx-G genes.