GTT1/StarD7, a novel phosphatidylcholine transfer protein-like highly expressed in gestational trophoblastic tumour: cloning and characterization.
We report the cDNA cloning and characterization of GTT1/StarD7, a novel gestational trophoblastic tumour gene, initially identified by its up-regulated expression in the choriocarcinoma JEG-3 cell line with respect to their nonmalignant counterpart, complete hydatidiform mole and normal trophoblastic tissue. Using the differential display fragment as a probe we screened placenta and HeLa cDNA libraries and isolated a clone carrying a 3315 bp insert (accession number AF270647). This cDNA encodes a protein of 295 amino acid residues with a molecular weight of approximately 34.7 kDa and a pI of 5.79. Computer-mediated homology search revealed that the deduced amino acid sequence had similarity to phosphatidylcholine transfer protein (PCTP) with a conserved StAR-related lipid transfer (START) domain extending between the amino acids 66 to 250. The GTT1 gene contains at least 9 exons spread nearly 30 kb on chromosome 2p12-2p11.2. Northern blot assays of total RNA derived from normal early placenta (NEP), complete hydatidiform mole (CHM) and JEG-3 cell line revealed a 3.5 kb mRNA expressed exclusively in the JEG-3 cell line. However, semiquantitative RT-PCR analysis performed with the same RNA samples demonstrated GTT1 expression throughout all of them with the highest level in JEG-3 cell line. Examination of GTT1 mRNA expression by semiquantitative RT-PCR assays in a series of tumour cell lines indicated wide-spread GTT1 expression with predominance in both choriocarcinoma JEG-3 and JAR cells, colorectal adenocarcinoma HT29 and hepatocellular carcinoma HepG2 cells. In conclusion, the highly GTT1 expression profile in JEG-3 and JAR cell lines and its lipid binding domain suggest that GTT1 may play an important role in the phospholipid-mediated signalling of trophoblastic tumour cellular events.
Durand
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Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad Universitaria, 5000 Córdoba, Argentina.
Angeletti
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Genti-Raimondi
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D000595:Amino Acid Sequence; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D002822:Choriocarcinoma / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D005260:Female; D015870:Gene Expression; D020869:Gene Expression Profiling; D015723:Gene Library; D031901:Gestational Trophoblastic Disease / Q000378:metabolism*; D019073:HT29 Cells; D006801:Humans; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D049294:Phospholipid Transfer Proteins; D011247:Pregnancy; D020133:Reverse Transcriptase Polymerase Chain Reaction; D040681:Structural Homology, Protein
D002352:Carrier Proteins; D018076:DNA, Complementary; D009363:Neoplasm Proteins; D049294:Phospholipid Transfer Proteins; C483475:STARD7 protein, human