Pinguid, the drosophila homolog of huntingtin interacting protein 14, encodes an essential protein involved in TGF beta signalling

To elucidate the cellular function of Huntingtin interacting protein 14 (Hipl4), a genetic approach using Drosophila was initiated. The gene encoding Pinguid was identified as the closest Drosophila homolog to human Hip14 with 44% identity and 59% similarity. A P-element insertion in the 5' UTR of pinguid was used for carrying out a transposase mediated P-element excision screen. Subsequent genetic and molecular experiments confirmed that pinguid encodes an essential gene. Five pinguid alleles were identified: three excision alleles and two EMS-induced alleles. No visible defects were observed in the mutants since the morphology and patterning of the embryos appeared normal, CNS development appeared wild type, and pharate adults had no visible external defects. However, the ectopic expression of pinguid identified genetic interactions with components of the TGFP signalling pathway. Strong genetic interactions were seen with short gastrulation, crossveinless 2, baboon, and the ecdysone receptor.