ABSTRACT
Eukaryotes inhibit the translation of mRNA under stress conditions and form particles-stress granules (stress granules). At present, stress granules have been proved to be related to the occurrence and development of a variety of diseases, including tumors. The production of stress granules is promoted by microenvironment such as hypoxia and hyperactive oxygen in tumor cells, while stress granules-related proteins such as G3BP1, RACK1, YB-1 and mammalian target of rapamycin (mTOR) can promote the occurrence and metastasis of tumors, but the mechanism is not yet clear. In addition, studies have linked the formation of stress granules to the survival of tumor cells during chemotherapy, and believe that stress granules play a role in the treatment of tumors by different anti-tumor drugs. This review introduces the biological characteristics of stress granules and their relationship with tumors.
ABSTRACT
When eukaryotic cells face various environment stimulation,eukaryotic cells form some dense granules in hyalomitome,that are stress granules(SGs).They have antioxidant and inhibit apoptosis. Interaction between mRNA-binding proteins promotes stress granule formation. Assembly and disassembly of stress granules are modulated by va-rious post-translational modifications as well as numerous ATP-dependent RNP or protein remodeling complexes.Stress granules have the ability of liquidity,and energy input is required to maintain their dynamic state.Stress granule for-mation can regulate the process of stress reaction,virus infection and the signal transduction.The formation of constant and the abnormal stress granules result in neurodegenerative diseases and certain types of cancer.
ABSTRACT
When eukaryotic cells face various environment stimulation,eukaryotic cells form some dense granules in hyalomitome,that are stress granules(SGs).They have antioxidant and inhibit apoptosis. Interaction between mRNA-binding proteins promotes stress granule formation. Assembly and disassembly of stress granules are modulated by va-rious post-translational modifications as well as numerous ATP-dependent RNP or protein remodeling complexes.Stress granules have the ability of liquidity,and energy input is required to maintain their dynamic state.Stress granule for-mation can regulate the process of stress reaction,virus infection and the signal transduction.The formation of constant and the abnormal stress granules result in neurodegenerative diseases and certain types of cancer.
ABSTRACT
Objective To construct eukaryotic enhanced green fluorescent protein (EGFP) expressing recombinant plasmid, pEGFP-C1-hnRNP A1, which contains coding sequence of human hnRNP A1 (heterogeneous nuclear ribonucleo-protein A1), and to perform cellular localization analysis of EGFP tagged hnRNP A1 under stress. Methods Total RNA was isolated from HeLa cell used for synthesis of first-strand cDNAs using reverse primers that are specific for the 3′-un-translated region of hnRNP A1. hnRNP A1 gene fragments were then amplified by touch-down PCR from those cDNAs and inserted into pEGFP-C1 fluorescent bearing vector through EcoRⅠ/BamHⅡdouble enzyme digestion and T4 DNA Ligase connection. The recombinant pEGFP-C1-hnRNP A1 plasmid was transfected into HeLa cells and green fluorescent tagged fusion proteins was examined by Western blot and confocal fluorescence microscopy. Co-localization of EGFP-hnRNP A 1 with poly (A)+mRNA (the marker of the stress granules), or DCP1a (the marker of processome) were detected by RNA fluores-cence in situ hybridization and immunofluorescence. Results The pEGFP-C1-hnRNP A1 was sequenced and digested cor-rectly by restriction single/double enzyme. The green fluorescent fusion protein was also detected in transfected HeLa cell by Western blot and confocal fluorescence microscopy. EGFP-hnRNP A1 co-localizes with poly(A)+mRNA, but not DCP1a. Conclusion Recombinant eukaryotic plasmid of pEGFP-C1-hnRNP A1 was constructed successfully and expressed effec-tively. EGFP tagged hnRNP A1 takes part in forming stress granules.
ABSTRACT
Objective To construct eukaryotic Flag (DYKDDDDK) expressing recombinant plasmids, pCMV-N-Flag-SND1-No1/2, which contain the coding sequence of human SND1-No1(from 1st AUG)or SND1-No2 (from 2nd AUG), and perform the cellular localization analysis of Flag-tagged SND1-No1/2 under stress condition to study the function of the two AUG in the SND1 containing stress granules formation. Methods The gene fragments of SND1-No1/2 were amplified by PCR from the whole SND1 transcript and inserted into pCMV-N-Flag expressing vector through BamHI/EcoRI double en-zyme digestion and T4 DNA Ligase connection. The recombinant pCMV-N-Flag-SND1-No1/2 plasmids were transfected in-to HeLa cells and the expression of Flag-SND1-No1/2 fusion proteins was examined by Western blotting assay. Immunofluo-rescence assay was performed to detect the co-localization of Flag-SND1-No1/2 with endogenous SND1 granule. Results The pCMV-N-Flag-SND1-No1/2 were sequenced and digested correctly by restriction single/double enzyme. The Flag-tagged SND1-No1/2 fusion proteins were also detected in transfected HeLa cell by Western blotting assay. Both of them showed the co-localization with endogenous SND1 granule. Conclusion The recombinant eukaryotic plasmids of pCMV-N-Flag-SND1-No1/2 were constructed successfully and expressed effectively. The depletion of 1st AUG failed to af-fect the formation of SND1 containing stress granules.
ABSTRACT
Viruses initiate a number of cellular stress responses and modulate gene regulation and compartmentalization of RNA upon infection to be successful parasites. Virus infections may induce or impair stress granule (SG) formation to maximize replication efficiency. SGs and processing bodies (PBs) are the RNA granules, which contain translationally inactive pool of transcripts as the mRNA silencing foci. PBs and SGs, the highly conserved macromolecular aggregates, can release mRNAs to allow their translations. Unlike constitutively existing PBs that can respond to stimuli and affect mRNA translation and decay, SGs are specifically induced upon cellular stress and can triggers a global translational silencing by several pathways, including phosphorylation of the key translation initiation factor eIF2alpha, tRNA cleavage, and sequestration of cellular components and so on. The dynamics of PBs and SGs are regulated by several signaling pathways, including histone deacetylase 6, and depend on microfilaments and microtubules, and the cognate molecular motors myosin, dynein, and kinesin. SGs share features with aggresomes and related aggregates of unfolded proteins and may play a role in the pathology. The recent advances in understanding the relationship between viruses and mRNA stress granules are summarized.