Gene expresión in trophoblastic tissues. Identification of two novel proteins: StarD7 and MTUS1

GENTI DE RAIMONDI SUSANA

Buenos Aires

Taller; I Taller de Interacción Materno-Fetal: de la Fisiología a la Patología; 2005

In an attempt to assess the molecular basis of phenotypic alterations present in the gestational trophoblastic diseases (GTDs) and to identify genes whose expression is specifically associated to these placental proliferative disorders we performed differential display techniques. Initially 23 candidate gene fragments were identified and differential expression was confirmed in fourteen of these fragments by Northern blot analysis. Eight of these fragments corresponded to transcripts predominantly expressed in early placenta, two in complete hydatidiform mole and four in the JEG-3 cell line. Two of these cDNA fragments, one of them over-expressed in normal early placenta (NEP) and the other predominantly expressed in JEG-3, was characterized. Using as a probe a 365 bp fragment over-expressed in NEP we isolated a clone carrying a 2952 bp insert (Accession number AY363099). This cDNA adds 512 pb in the 5´region and lacks 162 pb (2729-2982) to the longest sequence previously reported (AAB033114) encoding a truncated protein of 837 aa called NEP –Normal Early Placenta- (AAQ24172). The AY363099 nucleotide sequence is included in the GenBank database as a novel MTUS1 (Mitochondrial Tumor Suppressor 1) transcript isoform. By the other hand, the full length of cDNA highly expressed in JEG-3 encodes StarD7 protein, one of the 15 family members with START domain present in the human genome. Reverse transcriptase polymerase chain reaction and western blot analysis utilizing polyclonal antibodies obtained against these recombinant proteins allowed us to correlate these particular trophoblastic expressions. In addtion, immunofluorescence techniques demonstrated that NH-terminal isoforms of MTUS1 are predominantly localized in the nuclear compartment, in contrast, StarD7 is particularly localized in the cytoplasmic compartment. Further studies are currently performed in order to understand the role of these novel proteins in the pathogenesis of trophoblastic diseases.