The Trypanosoma cruzi nucleic acid binding protein Tc38 presents changes in the intramitochondrial distribution during the cell cycle

Background: Tc38 of Trypanosoma cruzi has been isolated as a single stranded DNA binding protein with high specificity for the poly [dT-dG] sequence. It is present only in Kinetoplastidae protozoa and its sequence lacks homology to known functional domains. Tc38 orthologues present in Trypanosoma brucei and Leishmania were proposed to participate in quite different cellular processes. To further understand the function of this protein in Trypanosoma cruzi, we examined its in vitro binding to biologically relevant [dT-dG] enriched sequences, its expression and subcellular localization during the cell cycle and through the parasite life stages.Results: By using specific antibodies, we found that Tc38 protein from epimastigote extracts participates in complexes with the poly [dT-dG] probe as well as with the universal minicircle sequence (UMS), a related repeated sequence found in maxicircle DNA, and the telomeric repeat. However, we found that Tc38 predominantly localizes into the mitochondrion. Though Tc38 is constitutively expressed through non-replicating and replicating life stages of T. cruzi, its subcellular localization in the unique parasite mitochondrion changes according to the cell cycle stage. in epimastigotes, Tc38 is found only in association with kDNA in G1 phase. From the S to G2 phase the protein localizes in two defined and connected spots flanking the kDNA. These spots disappear in late G2 turning into a diffuse dotted signal which extends beyond the kinetoplast. This later pattern is more evident in mitosis and cytokinesis. Finally, late in cytokinesis Tc38 reacquires its association with the kinetoplast. in non-replicating parasite stages such as trypomastigotes, the protein is found only surrounding the entire kinetoplast structure.Conclusions: the dynamics of Tc38 subcellular localization observed during the cell cycle and life stages support a major role for Tc38 related to kDNA replication and maintenance.FIRCAFondo Clemente Estable (DICyT)FAPESConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)PROSULPEDECIBAAMSUD-PasteurFac Ciencias, Lab Interacc Mol, Montevideo, UruguayFac Med, Dept Genet, Montevideo, UruguayFac Ciencias, Dept Biol Celular & Mol, Montevideo, UruguayInst Invest Biol Clemente Estable Montevideo Urug, Dept Neurobiol Celular & Mol, Montevideo, UruguayUniv Nacl Gen San Martin, CONICET, INTECH, Inst Invest Biotecnol, Buenos Aires, DF, ArgentinaUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, São Paulo, BrazilSUNY Buffalo, Dept Microbiol & Immunol, Buffalo, NY 14260 USAInst Biol Mol Parana, Curitiba, Parana, BrazilUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, São Paulo, BrazilFIRCA: R03 TW05665-01Fondo Clemente Estable (DICyT): 7109Web of Scienc

Nc886 is epigenetically repressed in prostate cancer and acts as a tumor suppressor through the inhibition of cell growth

Background: Nc886 is a 102 bp non-coding RNA transcript initially classified as a microRNA precursor (Pre-miR-886), later as a divergent homologue of the vault RNAs (vtRNA 2-1) and more recently as a novel type of RNA (nc886). Although nc886/vtRNA2-1/Pre-miR-886 identity is still controversial, it was shown to be epigenetically controlled, presenting both tumor suppressor and oncogenic function in different cancers. Here, we study for the first time the role of nc886 in prostate cancer. Methods: Nc886 promoter methylation status and its correlation with patient clinical parameters or DNMTs levels were evaluated in TCGA and specific GEO prostate tissue datasets. Nc886 level was measured by RT-qPCR to compare normal/neoplastic prostate cells from radical prostatectomies and cell lines, and to assess nc886 response to demethylating agents. The effect of nc886 recovery in cell proliferation (in vitro and in vivo) and invasion (in vitro) was evaluated using lentiviral transduced DU145 and LNCaP cell lines. The association between the expression of nc886 and selected genes was analyzed in the TCGA-PRAD cohort. Results: Nc886 promoter methylation increases in tumor vs. normal prostate tissue, as well as in metastatic vs. normal prostate tissue. Additionally, nc886 promoter methylation correlates with prostate cancer clinical staging, including biochemical recurrence, Clinical T-value and Gleason score. Nc886 transcript is downregulated in tumor vs. normal tissue -in agreement with its promoter methylation status- and increases upon demethylating treatment. In functional studies, the overexpression of nc886 in the LNCaP and DU145 cell line leads to a decreased in vitro cell proliferation and invasion, as well as a reduced in vivo cell growth in NUDE-mice tumor xenografts. Finally, nc886 expression associates with the prostate cancer cell cycle progression gene signature in TCGA-PRAD. Conclusions: Our data suggest a tumor suppressor role for nc886 in the prostate, whose expression is epigenetically silenced in cancer leading to an increase in cell proliferation and invasion. Nc886 might hold clinical value in prostate cancer due to its association with clinical parameters and with a clinically validated gene signature