ABSTRACT
Previously, we reported the presence in mouse cells of a mitochondrial RNA which contains an inverted repeat (IR) of 121 nucleotides (nt) covalently linked to the 5' end of the mitochondrial 16S RNA (16S mtrRNA). Here, we report the structure of an equivalent transcript of 2374 nt which is over-expressed in human proliferating cells but not in resting cells. The transcript contains a hairpin structure comprising an IR of 815 nt linked to the 5' end of the 16S mtrRNA and forming a long double-stranded structure or stem and a loop of 40 nt. The stem is resistant to RNase A and can be detected and isolated after digestion with the enzyme. This novel transcript is a non-coding RNA (ncRNA) and several evidences suggest that the transcript is synthesized in mitochondria. The expression of this transcript can be induced in resting lymphocytes stimulated with phytohaemagglutinin (PHA). Moreover, aphidicolin treatment of DU145 cells reversibly blocks proliferation and expression of the transcript. If the drug is removed, the cells re-assume proliferation and over-express the ncmtRNA. These results suggest that the expression of the ncmtRNA correlates with the replicative state of the cell and it may play a role in cell proliferation.
Subject(s)
Cell Proliferation , RNA, Untranslated/metabolism , RNA/metabolism , Gene Expression , Humans , Mitochondria/genetics , RNA/chemistry , RNA, Mitochondrial , RNA, Ribosomal, 16S/analysis , RNA, Untranslated/chemistry , Repetitive Sequences, Nucleic Acid , Ribonuclease, Pancreatic/metabolism , Transcription, GeneticABSTRACT
Se presenta el caso de un paciente que sufrió un infarto talámico izquierdo que se manifestó con obnubilación, afasia y hemiparesia derecha transitorias y con una amnesia persistente. La amnesia sería consecuencia de una lesión del núcleo dorsomedial, que tiene importantes conexiones con la corteza orbitaria y el sistema límbico. Esta amnesia es predominantemente verbal, reproduciendo asimetría funcional de los hemisferios cerebrales
