An isoform of Taiman that contains a PRD-repeat motif is indispensable for transducing the vitellogenic juvenile hormone signal in Locusta migratoria

Taiman (Tai) has been recently identified as the dimerizing partner of juvenile hormone (JH) receptor, Methoprene-tolerant (Met). However, the role of Tai isoforms in transducing vitellogenic signal of JH has not been determined. In this study, we show that the migratory locust Locusta migratoria has two Tai isoforms, which differ in an INDEL-1 domain with the PRD-repeat motif rich in histidine and proline at the C-terminus. Tai-A with the INDEL-1 is expressed at levels about 50-fold higher than Tai-B without the INDEL-1 in the fat body of vitellogenic adult females. Knockdown of Tai-A but not Tai-B results in a substantial reduction of vitellogenin expression in the fat body accompanied by the arrest of ovarian development and oocyte maturation, similar to that caused by depletion of both Tai isoforms. Either Tai-A or Tai-B combined with Met can induce target gene transcription in response to JH, but Tai-A appears to mediate a significantly higher transactivation. Our data suggest that the INDEL-1 domain plays a critical role in Tai function during reproduction as Tai-A appears be more active than Tai-B in transducing the vitellogenic JH signal in L. migratoria. [Display omitted] •Two Taiman (Tai) isoforms which differ by a PRD-repeat motif encoded by INDEL-1 have been identified in the migratory locust.•Tai-A with the INDEL-1 domain is more abundant in the adult female fat body than Tai-B that lacks INDEL-1.•Knockdown of Tai-A but not Tai-B substantially reduces vitellogenin gene expression and blocks oocyte maturation and ovarian development.•Tai-A is a stronger activator than Tai-B of gene expression induced by juvenile hormone through its receptor Met.