Seiji Yamauchi, Yohei Sasagawa, Teru Ogura, and Kunitoshi Yamanaka (2007) Differential expression pattern of UBX family genes in Caenorhabditis elegans . Biochem. Biophys. Res. Commun. 358, 545-552.
UBX (ubiquitin regulatory X)-containing proteins belong to an evolutionary conserved protein family and determine the specificity of p97/VCP/Cdc48p function by binding as its adaptors. Caenorhabditis elegans was found to possess six UBX-containing proteins, named UBXN-1 to -6. However, no general or specific function of them has been revealed. During the course of understanding not only their function but also specified function of p97 , we investigated spatial and temporal expression patterns of six ubxn genes in this study. Transcript analyses showed that the expression pattern of each ubxn gene was different throughout worm’s development and may show potential developmental dynamics in their function, especially ubxn-5 was expressed specifically in the spermatogenic germline, suggesting a crucial role in spermatogenesis. In addition, as ubxn-4 expression was induced by ER stress, it would function as an ERAD factor in C. elegans . In vivo expression analysis by using GFP translational fusion constructs revealed that six ubxn genes show distinct expression patterns. These results altogether demonstrate that the expression of all six ubxn genes of C. elegans is differently regulated.
Figure: (Left panel) The level of mRNAs of ubxn-4 was increased 3-fold, when worms were treated with 10 mM dithiothreitol (DTT) for 3 hours, which is a causative reagent for ER stress.
(Right panel) The ubxn-5 expression was obligatorily dependent on germline, as few expression was detected at L4 larval stage in glp-4 mutant. The level of ubxn-5 mRNA was significantly high in fem-3 ( gf ) mutant, which makes only sperms and never switches to oogenesis. In contrast, it was very low in fem-3 ( lf ) mutant, which makes only oocytes. These results suggest that ubxn-5 is expressed specifically in the spermatogenic germline.
