Calcineurin is a calcium/calmodulin-dependent serine/threonine protein phosphatase and is well known to have diverse cellular functions in different cell types and organisms. T23C6.3 has been screened as one of the candidate molecules which interact with calcineurin by Yeast-two-hybrid system. T23C6.3 is a nematode-specific novel gene in C.elegans. To find out the spatial and temporal expression pattern of T23C6.3, 2.2kb 5'upstream region and full-length genomic DNA of T23C6.3 fused with GFP was injected to wild-type animal. T23C6.3 is strongly expressed in the nucleus of intestine, hypodermis, vulva and uterine regions and the expression begins around 60-cell stage and progresses all larval stages and adult. To elucidate the biological function of T23C6.3 in C.elegans, a mutant
(jh145) has been isolated by PCR-based TMP-UV mutagenesis method. The mutant has a deletion of 880 base pairs from exon 2 to exon 3 which leads to a premature termination of translation. Since T23C6.3 is a potential calcineurin binding partner, several calcineurine-defective phenotypes such as brood size, body size, serotonin- and levamisole-mediated egg-laying, were tested. The mutant
(jh145) showed no significant difference to wild-type animal in those assays. However, the double mutants,
tax-6(
p675);T23C6.3
(jh145) and
cnb-1(
jh103);T23C6.3
(jh145), are more severe in terms of brood size, body size and serotonin- and levamisole-mediated egg-laying compare to
tax-6(
p675) and
cnb-1(
jh103) respectively. These results suggest that the mutation of T23C6.3 enhances the calcineurin-mutant phenotypes and thus, T23C6.3 genetically interacts with calcineurin. To make sure the direct interaction of T23C6.3 with calcineurin, we are currently investigating the physical interaction between T23C6.3 and calcineurin by in vitro-binding assay.