| Sažetak | MiRNA razred su malih (~22-25 nukleotida), jednolančanih, evolucijski vrlo očuvanih, nekodirajućih
molekula RNA koje imaju specifičnu ulogu u kontroli genske ekspresije na post-translacijskoj i transkripcijskoj
razini. Kod životinja se miRNA sintetiziraju u dva koraka, djelovanjem dva enzima endoribonukleaza III
(RNaza III) lokalizirana u jezgri i citoplazmi, dok se dorada miRNA u biljkama u cijelosti odvija u citoplazmi
i provodi pomoću jedne RNaze III. Kao dio kompleksa miRISC, zrela miRNA prepoznaje ciljnu mRNA.
Nakon prepoznavanja, ovisno o stupnju komplementarnosti, dolazi do egzonukleazne aktivnosti proteina Ago.
Kod životinja je utvrđeno da miRNA reguliraju signalne putove te osnovne stanične procese poput
proliferacije, diferencijacije, te da imaju važnu ulogu u neuralnom razvoju, imunitetu te održavanju homeostaze
reguliranjem programirane stanične smrti, , itd. Biljne pak miRNA na specifičan način reguliraju razvoj biljnih
organa poput listova i cvijeta, kao i vaskularni razvoj, homeostazu fitohormona i nutrijenata, a uključene su i
u odgovor na stres do kojeg dolazi uslijed djelovanja biotičkih i abiotičkih čimbenika. |
| Sažetak (engleski) | MicroRNAs (miRNAs) are a class of small, noncoding RNAs, approximatey ~22-25
nucleotides long, single-standed, evolutionary conserved, which are known to play specific regulatory role on
post-transcription and transcription level. In animals, miRNAs synthesizes occurs in two steps, processed by
two exoribonucleases III (RNase III), which are localised in nucleus and cytoplasm, while plant miRNA
processing is dependent on one RNase III, which is localised in cytoplasm. As a part of microRNA-induced
silencing complex, miRNAs are able to recognise the target mRNAs. After recognition, depending on the
degree of complementarity, the exonuclease (slicer) activity of Ago protein occurs. In animals, it was
determined that miRNA regulates signal pathways and basic cellular processes such as proliferation,
differentiation, and play an important role in neural development, immunity, and homeostatic maintenance by
regulating programmed cell death, etc. Plants miRNAs specifically regulate the development of plant organs
such as leaves and flowers, as well as vascular development, phytohormones and nutrition homeostasis, and
are included in response to the stress caused by the action of biotic and abiotic factors. |
