Relazione tra la proteina La e la regolazione traduzionale dei messaggeri TOP

摘要: TOP mRNAs encode for ribosomal proteins, elongation factors and several other proteins associated with the assembly or function of translational apparatus. These messengers are identified by two major characteristics : i) a 5’ terminal oligopyrimidine tract (TOP motif), ii) growth- dependent regulation. It has been shown both in vitro (cultured cells) vivo that perturbation cellular growth, due to variety causes (development, mitogens, drugs etc.), is correlated specific, rapid reversible changes polysomal association. found 5’-UTR these mRNAs, including sequence, cis- acting element responsible regulation but trans-acting pathways involved remain incompletely understood. Several studies reported La may play role mRNA regulation, its precise this process remains be determined. an evolutionary conserved abundant RNA-binding phosphoprotein, present mostly nucleus, where 3’ poly(U)-rich elements nascent RNA polymerase III (pol III) transcripts. A protein protect newly synthesized small RNAs from exonuclease digestion, ensuring they correctly folded processed. However, despite mainly nuclear localization, cytoplasmic functions connected translation have ascribed La. The best documented most studied cytoplasm initiation certain viral RNAs. About some reports describe positive effect on translation, while authors define inhibitory protein. For reason, we constructed analyzed human cell lines overexpress wild type mutated lacking localization signal (NLS). Our results indicate that, serum deprivated cells growing cells, overexpression does not alter significantly association polysomes. As experimental approach alternative utilized interference induce decrease 70% reduction level cause visible consequences translation. It’s known part Ro ribonucleoprotein (RNP) complex, which also includes Ro60 Y , it required binding element. Therefore decided investigate possible involvement RNP complex complexes particles unknown well during evolution expressed all types cells. We performed sedimentation analysis extracts fractionated sucrose gradients pelletted centrifugation, La, 60 cosediment polysomes different growth conditions. sequence demonstrated independent groups, can hypothesized recruits mRNA. Although proven, abolishes Y1 cosedimentation Taken together, our data consistent