RESUMEN
PEDV, a single-stranded RNA virus, causes significant economic losses in the pig industry. Sin3-associated protein 18 (SAP18) is known for its role in transcriptional inhibition and RNA splicing. However, research on SAP18's involvement in PEDV infection is limited. Here, we identified an interaction between SAP18 and PEDV nonstructural protein 10 (Nsp10) using immunoprecipitation-mass spectrometry (IP-MS) and confirmed it through immunoprecipitation and laser confocal microscopy. Additionally, PEDV Nsp10 reduced SAP18 protein levels and induced its cytoplasmic accumulation. Overexpressing SAP18 suppressed PEDV replication, meanwhile its knockdown via short interfering RNA (siRNA) enhanced replication. SAP18 overexpression boosted IRF3 and NF-κB P65 phosphorylation, nuclear translocation, and IFN-ß antiviral response. Furthermore, SAP18 upregulated RIG-I expression and facilitated its dephosphorylation, while SAP18 knockdown had the opposite effect. Finally, SAP18 interacted with phosphatase 1 (PP1) catalytic subunit alpha (PPP1CA), promoting PPP1CA-RIG-I interaction during PEDV infection. These findings highlight SAP18's role in activating the type I interferon pathway and inhibiting viral replication by promoting RIG-I dephosphorylation through its interaction with PPP1CA.
Asunto(s)
Virus de la Diarrea Epidémica Porcina , Proteínas no Estructurales Virales , Replicación Viral , Animales , Proteínas no Estructurales Virales/metabolismo , Proteínas no Estructurales Virales/genética , Virus de la Diarrea Epidémica Porcina/fisiología , Virus de la Diarrea Epidémica Porcina/genética , Fosforilación , Porcinos , Línea Celular , Proteína 58 DEAD Box/metabolismo , Proteína 58 DEAD Box/genética , Chlorocebus aethiopsRESUMEN
Sin3 associated protein 18 (SAP18) is an evolutionary conserved protein, originally discovered in a complex with the transcriptional regulatory protein, Sin3. Subsequent investigations revealed SAP18 as an integral splicing component of the exon junction complex (EJC)-associated apoptosis-and splicing-associated protein (ASAP)/PNN-RNPS1-SAP18 (PSAP) complex. In association with Sin3, SAP18 contributes toward transcriptional repression of genes implicated in embryonic development, stress response, human immunodeficiency virus type 1 replication, and tumorigenesis. As a part of EJC, SAP18 mediates alternative splicing events and suppresses the cryptic splice sites present within flanking regions of exon-exon junctions. In this review, we provide a thorough discussion on SAP18, focussing on its conserved dual role in transcriptional regulation and messenger RNA splicing. Recent research on the involvement of SAP18 in the emergence of cancer and human disorders has also been highlighted. The potential of SAP18 as a therapeutic target is also discussed in these recent studies, particularly related to malignancies of the myeloid lineage.
Asunto(s)
Proteínas de Unión al ARN , Ribonucleoproteínas , Humanos , Empalme Alternativo , Expresión Génica , Ribonucleoproteínas/metabolismo , Empalme del ARN , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismoRESUMEN
Aberrant regulation of microRNA expression in pancreatic cancers has been shown to play an important role in its inherent poor prognosis and malignant potential. MicroRNAs have also been shown to inhibit translation of genes by targeting the 3'-untranslated region (3-UTR) of mRNAs resulting in the inhibition of translation and often destruction of the mRNA. In the present study we investigated the role of the microRNA miR-202 in the apoptotic pathways of pancreatic cancer cells. The adamantyl-related molecule, 3-Cl-AHPC down-regulated expression of miR-202 and miR-578 resulting in the increased expression of mRNA and protein expression of their target genes, Max dimerization protein 1 (Mxd1/Mad1) and the Sin3A associated protein 18 (SAP18). Overexpression of pre-miR-202 led to diminished levels of Mxd1 and blocked the 3-Cl-AHPC-mediated increase in Mxd1 mRNA expression. The addition of the microRNA inhibitor 2'-O-methylated miR-202 enhanced the 3-Cl-AHPC-mediated increase of Mxd1 mRNA levels as well as 3-CI-AHPC-mediated apoptosis. We found increased Mxd1 bound to the Sin3A repressor protein complex through its increased binding with HDAC-2 and subsequently enhanced transcriptional repression in cells as evidenced by increased HDAC activity. Mxd1 also repressed human telomerase reverse transcriptase (hTERT) mRNA expression through its increased binding to the hTERT promoter site and resulted in decreased telomerase activity in cells. Our results demonstrate that down regulation of miR-202 increased the expression of its target Mxd1, followed by Mxd1 recruitment to the Sin3A repressor complex and through its dimerization with Max, and increased repression of Myc-Max target proteins.
Asunto(s)
Apoptosis/genética , Factores de Transcripción Básicos con Cremalleras de Leucinas y Motivos Hélice-Asa-Hélice/genética , Regulación Neoplásica de la Expresión Génica , MicroARNs/genética , Neoplasias Pancreáticas/genética , Proteínas Represoras/genética , Regiones no Traducidas 3' , Adamantano/análogos & derivados , Adamantano/farmacología , Apoptosis/efectos de los fármacos , Línea Celular Tumoral , Cinamatos/farmacología , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Unión Proteica , Interferencia de ARN , Complejo Correpresor Histona Desacetilasa y Sin3 , Telomerasa/genética , Telomerasa/metabolismoRESUMEN
There is ample evidence that synthesis of HIV-1 proviral DNA from the viral RNA genome during reverse transcription requires host factors. However, only a few cellular proteins have been described in detail that affect reverse transcription and interact with reverse transcriptase (RT). HIV-1 integrase is an RT binding protein and a number of IN-binding proteins including INI1, components of the Sin3a complex, and Gemin2 affect reverse transcription. In addition, recent studies implicate the cellular proteins HuR, AKAP149, and DNA topoisomerase I in reverse transcription through an interaction with RT. In this review we will consider interactions of reverse transcription complex with viral and cellular factors and how they affect the reverse transcription process.