{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T07:06:26Z","timestamp":1774940786798,"version":"3.50.1"},"reference-count":47,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T00:00:00Z","timestamp":1774915200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Cell. Infect. Microbiol."],"abstract":"<jats:sec>\n                    <jats:title>Objective(s)<\/jats:title>\n                    <jats:p>Hepatitis B virus (HBV) replication is tightly controlled by host stress and innate immune pathways. The small noncoding RNA nc886 (vtRNA2-1) is a known endogenous inhibitor of protein kinase R (PKR), but its role in HBV biology remains unclear. This study aimed to define the function of the nc886\u2013PKR\u2013eIF2\u03b1 axis in HBV-replicating hepatoma cells and to determine whether nc886 depletion suppresses HBV replication via PKR-dependent translational control.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Materials and methods<\/jats:title>\n                    <jats:p>Huh7 cells and Huh7 cells stably harboring a 1.3-mer HBV replicon were used. Endogenous nc886 and PKR expression was assessed by RT-qPCR and Western blot. Loss-of-function experiments employed two independent siRNAs against nc886 and one siRNA against PKR, alone or in combination, with scramble siRNA as control. PKR activation was induced by Poly(I:C); PKR and integrated stress response (ISR) were pharmacologically modulated using C16 (PKR inhibitor) and ISRIB (eIF2B activator), at non-toxic doses defined by MTT assay. Intracellular HBV DNA was measured by Southern blot, HBV pgRNA and subgenomic RNAs by Northern blot and RT-qPCR, and secreted HBsAg\/HBeAg by ELISA. PKR\u2013eIF2\u03b1\u2013ATF4 signaling was evaluated by Western blot.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>nc886 and PKR were efficiently and specifically knocked down without affecting cell viability. nc886 silencing in Huh7\u2013HBV cells increased PKR-dependent eIF2\u03b1 phosphorylation and ATF4, reduced HBV pgRNA and subgenomic RNAs, and decreased intracellular HBV DNA and secreted HBsAg\/HBeAg. PKR knockdown alone slightly enhanced HBV readouts and completely rescued nc886-mediated inhibition of HBV replication and ISR activation in dual-knockdown cells. C16 or ISRIB restored HBV DNA, RNA and antigen production in nc886-silenced or Poly(I:C)-treated cells, while having no effect in control cells, indicating that rescue depended on ISR modulation.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>nc886 acts as a critical negative regulator of PKR-dependent ISR signaling during HBV replication in Huh7 cells. Its depletion activates PKR and eIF2\u03b1, imposing a translational block that suppresses HBV gene expression. The nc886\u2013PKR\u2013eIF2\u03b1 module represents a novel host regulatory axis with potential relevance for host-directed HBV therapies.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fcimb.2026.1742078","type":"journal-article","created":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T05:34:27Z","timestamp":1774935267000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["nc886 noncoding RNA regulates hepatitis B virus replication via PKR-dependent eIF2\u03b1 phosphorylation"],"prefix":"10.3389","volume":"16","author":[{"given":"Zahra Zahid","family":"Piracha","sequence":"first","affiliation":[{"name":"Szechenyi Istvan University, Egyetem Square 1","place":["Gyor, Hungary"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Umar","family":"Saeed","sequence":"additional","affiliation":[{"name":"University College, Korea University","place":["Seoul, Republic of Korea"]},{"name":"Institute of Graduate Studies and Research, Cyprus International University","place":["Nicosia, Cyprus"]}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1965","published-online":{"date-parts":[[2026,3,31]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.1016\/j.heliyon.2021.e06800","article-title":"Review on the occurrence of the mcr-1 gene causing colistin resistance in cow\u2019s milk and dairy products","volume":"7","author":"Ashaolu","year":"2021","journal-title":"Heliyon."},{"key":"B2","doi-asserted-by":"publisher","first-page":"113","DOI":"10.1016\/j.mib.2016.05.015","article-title":"Innate immune evasion strategies of DNA and RNA viruses","volume":"32","author":"Beachboard","year":"2016","journal-title":"Curr. Opin. Microbiol."},{"key":"B3","doi-asserted-by":"publisher","first-page":"557","DOI":"10.1261\/rna.060269.116","article-title":"nc886 adopts two opposing conformations regulating PKR","volume":"23","author":"Calderon","year":"2017","journal-title":"RNA."},{"key":"B4","doi-asserted-by":"publisher","first-page":"4511","DOI":"10.1096\/fj.11-187781","article-title":"A liver-specific microRNA binds HBV RNA and suppresses replication","volume":"25","author":"Chen","year":"2011","journal-title":"FASEB J."},{"key":"B5","doi-asserted-by":"publisher","first-page":"1779","DOI":"10.1002\/hep.29348","article-title":"Hepatitis B virus evades innate immunity of hepatocytes but activates cytokine production by macrophages","volume":"66","author":"Cheng","year":"2017","journal-title":"Hepatology."},{"key":"B6","doi-asserted-by":"publisher","first-page":"1","DOI":"10.1080\/15476286.2025.2512610","article-title":"Deciphering the multifaceted role of protein kinase R: pathophysiological function beyond the antiviral response","volume":"22","author":"Chung","year":"2025","journal-title":"RNA Biol."},{"key":"B7","doi-asserted-by":"publisher","DOI":"10.3389\/fnmol.2018.00480","article-title":"PKR: A kinase to remember","volume":"11","author":"Gal-Ben-Ari","year":"2019","journal-title":"Front. Mol. Neurosci."},{"key":"B8","doi-asserted-by":"publisher","first-page":"796","DOI":"10.1016\/S2468-1253(22)00124-8","article-title":"Global, regional, and national burden of hepatitis B, 1990\u20132019: a systematic analysis for the Global Burden of Disease Study 2019","volume":"7","year":"2022","journal-title":"Lancet Gastroenterol. Hepatol."},{"key":"B9","doi-asserted-by":"publisher","first-page":"100536","DOI":"10.1016\/j.gastha.2024.08.015","article-title":"Nucleos(t)ide analog treatment discontinuation in chronic hepatitis B virus infection: a systematic literature review","volume":"4","author":"Gish","year":"2025","journal-title":"Gastro Hepatol. Adv."},{"key":"B10","doi-asserted-by":"publisher","first-page":"2640","DOI":"10.1038\/s41467-019-10606-1","article-title":"Structural basis for inhibition of translation through eIF2\u03b1 phosphorylation","volume":"10","author":"Gordiyenko","year":"2019","journal-title":"Nat. Commun."},{"key":"B11","doi-asserted-by":"publisher","first-page":"457","DOI":"10.1080\/10643389.2020.1732780","article-title":"Co-composting with herbal wastes: Potential effects of essential oil residues on microbial pathogens during composting","volume":"51","author":"Greff","year":"2021","journal-title":"Crit. Rev. Environ. Sci. Technol."},{"key":"B12","doi-asserted-by":"publisher","first-page":"123771","DOI":"10.1016\/j.envres.2026.123771","article-title":"Colistin residues and colistin-resistant Enterobacteriaceae in agricultural soils: Sources, risks, and remediation strategies","volume":"294","author":"Greff","year":"2026","journal-title":"Environ. Res"},{"key":"B13","doi-asserted-by":"publisher","DOI":"10.3390\/plants12040706","article-title":"Biocontrol activity of aromatic and medicinal plants and their bioactive components against soil-borne pathogens","volume":"12","author":"Greff","year":"2023","journal-title":"Plants (Basel)."},{"key":"B14","doi-asserted-by":"publisher","DOI":"10.1016\/j.jenvman.2021.114088","article-title":"Influence of microbial inoculants on co-composting of lignocellulosic crop residues with farm animal manure: A review","volume":"302","author":"Greff","year":"2022","journal-title":"J. Environ. Manage."},{"key":"B15","doi-asserted-by":"publisher","first-page":"e27931","DOI":"10.1371\/journal.pone.0027931","article-title":"PKR activation in HBx-siRNA innate response suppresses HBV","volume":"6","author":"Han","year":"2011","journal-title":"PloS One"},{"key":"B16","doi-asserted-by":"publisher","DOI":"10.3390\/cells10092258","article-title":"Anti-viral pattern recognition receptors as therapeutic targets","volume":"10","author":"Hennessy","year":"2021","journal-title":"Cells."},{"key":"B17","doi-asserted-by":"publisher","DOI":"10.3390\/ijms251910825","article-title":"The versatile roles of nc886, a fascinating and peculiar regulatory non-coding RNA","volume":"25","author":"Jang","year":"2024","journal-title":"Int. J. Mol. Sci."},{"key":"B18","doi-asserted-by":"publisher","first-page":"3477","DOI":"10.1016\/j.febslet.2012.07.076","article-title":"Characterization of the direct physical interaction of nc886 and PKR","volume":"586","author":"Jeon","year":"2012","journal-title":"FEBS Lett."},{"key":"B19","doi-asserted-by":"publisher","first-page":"1909","DOI":"10.1038\/s12276-024-01307-x","article-title":"RNA variations in cancer","volume":"56","author":"Kim","year":"2024","journal-title":"Exp. Mol. Med."},{"key":"B20","doi-asserted-by":"publisher","first-page":"3453","DOI":"10.52091\/EVIK-2021\/2-4-ENG","article-title":"Characterization of Serratia species and qualitative detection of Serratia marcescens in raw and pasteurized milk by an analytical method based on polymerase chain reaction","volume":"67","author":"Korcz","year":"2021","journal-title":"J. Food Investig."},{"key":"B21","doi-asserted-by":"publisher","first-page":"1715","DOI":"10.1128\/AAC.41.8.1715","article-title":"Inducible expression of HBV in stably transfected hepatoblastoma cells","volume":"41","author":"Ladner","year":"1997","journal-title":"Antimicrob. Agents Chemother."},{"key":"B22","doi-asserted-by":"publisher","DOI":"10.3390\/ijms24108533","article-title":"nc886, a Pol III-transcribed ncRNA with dynamic regulation","volume":"24","author":"Lee","year":"2023","journal-title":"Int. J. Mol. Sci."},{"key":"B23","doi-asserted-by":"publisher","first-page":"75000","DOI":"10.18632\/oncotarget.11852","article-title":"nc886, a non-coding RNA and suppressor of PKR, exerts an oncogenic function in thyroid cancer","volume":"7","author":"Lee","year":"2016","journal-title":"Oncotarget."},{"key":"B24","doi-asserted-by":"publisher","first-page":"e0120450","DOI":"10.1371\/journal.pone.0120450","article-title":"A novel type of non-coding RNA, nc886, implicated in tumorigenesis","volume":"10","author":"Lee","year":"2015","journal-title":"PloS One"},{"key":"B25","doi-asserted-by":"publisher","first-page":"3944","DOI":"10.18632\/oncotarget.2047","article-title":"nc886 is suppressed by CpG methylation in gastric cancer","volume":"5","author":"Lee","year":"2014","journal-title":"Oncotarget."},{"key":"B26","doi-asserted-by":"publisher","first-page":"647","DOI":"10.1016\/j.bbrc.2019.01.068","article-title":"nc886 inhibits UVB-induced MMP-9\/COX-2 via PKR","volume":"512","author":"Lee","year":"2019","journal-title":"Biochem. Biophys. Res. Commun."},{"key":"B27","doi-asserted-by":"publisher","first-page":"10321","DOI":"10.1093\/nar\/gkv1078","article-title":"Robust expression of vault RNAs induced by influenza A virus plays a critical role in suppression of PKR-mediated innate immunity","volume":"43","author":"Li","year":"2015","journal-title":"Nucleic Acids Res."},{"key":"B28","doi-asserted-by":"publisher","DOI":"10.3389\/fimmu.2025.1639763","article-title":"Small non-coding RNAs: key regulatory factors and potential therapeutic targets in tumor immunity","volume":"16","author":"Liu","year":"2025","journal-title":"Front. Immunol."},{"key":"B29","doi-asserted-by":"publisher","DOI":"10.1016\/j.prp.2023.154725","article-title":"Emerging role of miR-122 in infectious diseases","volume":"249","author":"Mirzaei","year":"2023","journal-title":"Pathol. Res. Pract."},{"key":"B30","doi-asserted-by":"publisher","DOI":"10.1016\/j.foodcont.2021.108236","article-title":"A rapid and efficient DNA isolation method for qPCR-based detection of pathogenic and spoilage bacteria in milk","volume":"130","author":"Pancza","year":"2021","journal-title":"Food Control."},{"key":"B31","doi-asserted-by":"publisher","first-page":"167","DOI":"10.1007\/s10059-011-1059-6","article-title":"PKR-dependent mechanisms of IFN-\u03b1 inhibit HBV replication","volume":"32","author":"Park","year":"2011","journal-title":"Mol. Cells"},{"key":"B32","doi-asserted-by":"publisher","first-page":"e00926","DOI":"10.1128\/JVI.00926-20","article-title":"A Sirtuin 2 isoform inhibits HBV replication from cccDNA","volume":"94","author":"Piracha","year":"2020","journal-title":"J. Virol."},{"key":"B33","doi-asserted-by":"publisher","DOI":"10.3390\/ijms18122505","article-title":"Long non-coding RNAs in HBV-related HCC","volume":"18","author":"Qiu","year":"2017","journal-title":"Int. J. Mol. Sci."},{"key":"B34","doi-asserted-by":"publisher","first-page":"2097","DOI":"10.1073\/pnas.1815767116","article-title":"ISRIB suppresses integrated stress response","volume":"116","author":"Rabouw","year":"2019","journal-title":"Proc. Natl. Acad. Sci. U.S.A."},{"key":"B35","doi-asserted-by":"publisher","first-page":"68","DOI":"10.1186\/s13148-025-01871-7","article-title":"Regulation of nc886 RNAs and cardiometabolic diseases","volume":"17","author":"Raji\u0107","year":"2025","journal-title":"Clin. Epigenet."},{"key":"B36","doi-asserted-by":"crossref","first-page":"545","DOI":"10.1016\/S2468-1253(19)30119-0","article-title":"A global scientific strategy to cure hepatitis B","volume":"4","author":"Revill","year":"2019","journal-title":"Lancet Gastroenterol. Hepatol."},{"key":"B37","doi-asserted-by":"publisher","DOI":"10.3389\/fmicb.2023.921653","article-title":"PIN1 and PIN4 inhibition by parvulin impeders suppresses HBV replication","volume":"14","author":"Saeed","year":"2023","journal-title":"Front. Microbiol."},{"key":"B38","doi-asserted-by":"publisher","DOI":"10.3389\/fmicb.2021.795047","article-title":"HBV core protein binds Par14\/Par17 to enhance stability and replication","volume":"12","author":"Saeed","year":"2021","journal-title":"Front. Microbiol."},{"key":"B39","doi-asserted-by":"publisher","DOI":"10.3390\/v9050125","article-title":"A role for the host DNA damage response in hepatitis B virus cccDNA formation, and beyond","volume":"9","author":"Schreiner","year":"2017","journal-title":"Viruses."},{"key":"B40","doi-asserted-by":"publisher","first-page":"1005","DOI":"10.1073\/pnas.84.4.1005","article-title":"Production of hepatitis B virus particles in HepG2 cells transfected with cloned HBV DNA","volume":"84","author":"Sells","year":"1987","journal-title":"Proc. Natl. Acad. Sci. U.S.A."},{"key":"B41","doi-asserted-by":"publisher","DOI":"10.3390\/ani10071163","article-title":"Bacteriological quality of raw ovine milk from different sheep farms","volume":"10","author":"Tema","year":"2020","journal-title":"Anim. (Basel)."},{"key":"B42","doi-asserted-by":"publisher","DOI":"10.3390\/w15091757","article-title":"Effect of simulated transport conditions on microbiological properties of bottled natural mineral water","volume":"15","author":"Tihanyi-Kov\u00e1cs","year":"2023","journal-title":"Water."},{"key":"B43","doi-asserted-by":"publisher","DOI":"10.1101\/cshperspect.a032870","article-title":"Role of eIF2\u03b1 kinases in translational control and adaptation to cellular stress","volume":"10","author":"Wek","year":"2018","journal-title":"Cold Spring Harb. Perspect. Biol."},{"key":"B44","volume-title":"Global hepatitis report 2024: Action for access in low- and middle-income countries","year":"2024"},{"key":"B45","doi-asserted-by":"publisher","first-page":"503","DOI":"10.1002\/hep.31284","article-title":"HBV polymerase restrains viral replication via CREB1\/HOXA13 axis","volume":"73","author":"Zhao","year":"2021","journal-title":"Hepatology."},{"key":"B46","doi-asserted-by":"publisher","first-page":"1934","DOI":"10.1261\/rna.7150804","article-title":"PKR activation by short dsRNAs with ssRNA tails","volume":"10","author":"Zheng","year":"2004","journal-title":"RNA."},{"key":"B47","doi-asserted-by":"publisher","first-page":"193","DOI":"10.2495\/WS190171","article-title":"Microbiological testing of drinking water in the Western Transdanubian region of Hungary using API tests","volume":"239","author":"Zseni","year":"2019","journal-title":"WIT Trans. Ecol. Environ."}],"container-title":["Frontiers in Cellular and Infection Microbiology"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fcimb.2026.1742078\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T05:34:28Z","timestamp":1774935268000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fcimb.2026.1742078\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,3,31]]},"references-count":47,"alternative-id":["10.3389\/fcimb.2026.1742078"],"URL":"https:\/\/doi.org\/10.3389\/fcimb.2026.1742078","relation":{},"ISSN":["2235-2988"],"issn-type":[{"value":"2235-2988","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,3,31]]},"article-number":"1742078"}}