The tumor susceptibility gene TSG101 is a recently discovered gene whose functional knockout in mouse fibroblasts leads to transformation and tumor formation in nude mice. Human and mouse TSG101 cDNAs are 86% and 94% similar at the nucleotide and deduced amino acid levels, respectively. The highly conserved protein sequences suggest that the mouse and human TSG101 are true gene homologs that share fundamental biological functions. Here, we report that the turtle TSG101 full-length cDNA sequence contained a 1,176-base-pair open translational reading frame predicted to encode a 392-amino-acid protein. Alignment of TSG101 sequences showed that the turtle cDNA sequence was 82.3% and 84.4% similar to mouse and human TSG101, respectively, at the nucleotide level and 89.3% and 91.9% similar to mouse and human TSG101 proteins, respectively. A coiled-coil domain and a proline-rich region typical of the activation domain of transcription factors were highly conserved among the turtle, mouse, and human TSG101. The leucine zipper motifs in the coiled-coil domains of turtle, mouse, and human TSG101 proteins were identical. Expression of TSG101 was observed in all turtle organs examined. The role of TSG101 in green turtle fibropapilloma (GTFP) was investigated by performing reverse transcriptase-polymerase chain reaction (RT-PCR) on RNA derived from various turtle tumor tissues and tumor cell lines. No transcript abnormalities of turtle TSG101 were found in all examined GTFP samples (10 GTFP tumor tissues and 2 GTFP tumor cell lines) from RT-PCR products. Future study will analyze the difference in turtle TSG101 expressions between GTFP and the corresponding normal tissue. In mammalian systems, TSG101 productions outside of a narrow range, either overexpression or deficiency, can lead to abnormal cell growth. It needs to be clarified whether turtle TSG101 in GTFP is up or down regulated.
Read full abstract