A population of tRNA-derived small RNAs is actively produced in Trypanosoma cruzi and recruited to specific cytoplasmic granules.
Over the last years an expanding family of small RNAs (i.e. microRNAs, siRNAs and piRNAs) was recognized as key players in diverse forms of gene silencing and chromatin organization. Effectors functions of these small RNAs are achieved through ribonucleoprotein (RNP) complexes containing at their center an Argonaute/Piwi protein. Although these proteins and their small RNA-associated machinery can be traced back to the common ancestor of eukaryotes, this machinery seems to be entirely lost or extensively simplified in some unicellular organisms including Trypanosoma cruzi, which are unable to trigger RNAi related phenomena. Speculating about the presence of alternate small RNA-mediated pathways in these organisms, we constructed and analyzed a size-fractionated cDNA library (20-35 nt) from epimastigotes forms of T. cruzi. Our results showed the production of an abundant class of tRNA-derived small RNAs preferentially restricted to specific isoacceptors and whose production was more accentuated under nutritional stress. These small tRNAs derived preferentially from the 5' halves of mature tRNAs and were recruited to distinctive cytoplasmic granules. Our data favor the idea that tRNA cleavage is unlikely to be the consequence of non-specific degradation but a controlled process, whose biological significance remains to be elucidated.
Functional Genomics Unit, Institut Pasteur de Montevideo, Mataojo 2020, CP11400 Montevideo, Uruguay.
Maria Rosa
MR
Garcia-Silva
Magali
M
Frugier
Juan Pablo
JP
Tosar
Alejandro
A
Correa-Dominguez
Lysangela
L
Ronalte-Alves
Adriana
A
Parodi-Talice
Carlos
C
Rovira
Carlos
C
Robello
Samuel
S
Goldenberg
Alfonso
A
Cayota
D003594:Cytoplasmic Granules / Q000737:chemistry / Q000378:metabolism*; D016053:RNA, Protozoan / Q000235:genetics* / Q000378:metabolism*; D012343:RNA, Transfer / Q000235:genetics / Q000378:metabolism; D022661:RNA, Untranslated / Q000235:genetics* / Q000378:metabolism*; D014349:Trypanosoma cruzi / Q000235:genetics / Q000378:metabolism*
D016053:RNA, Protozoan; D022661:RNA, Untranslated; D012343:RNA, Transfer