title: Gene Silencing and Activation of Human Papillomavirus 18 Is Modulated by Sense Promoter Associated RNA in Bidirectionally Transcribed Long Control Region.
abstract: BACKGROUND
  Recently various studies have demonstrated the role of promoter associated non-coding RNAs (pRNA) in dsRNA induced transcriptional gene silencing and activation. However the exact mechanistic details of these processes with respect to the orientation of pRNAs are poorly defined.
  
  
  RESULTS
  We have identified novel sense and antisense long control region (LCR) associated RNAs (pRNAs) in HPV18 positive cervical cancer cell lines HeLa, C-4 I and C-4 II. Using dsRNAs against these pRNAs, we were able to achieve upregulation or downregulation of the sense and antisense pRNAs and the downstream E6 and E7 oncogenes. We present evidence that knockdown of the sense pRNA is associated with reduction in E6 and E7 oncogenes and an upregulation of antisense pRNA. Conversely upregulation of sense pRNA is accompanied by an induction of the oncogenes and a concomitant reduction in antisense pRNA. Moreover, the exact role of sense and antisense pRNAs in dsRNA mediated gene modulation was confirmed by their selective degradation using antisense phosphorothioate oligodeoxynucleotides (ODN). Degradation of sense pRNA with antisense ODN led to loss of dsRNA induced silencing and activation, suggesting that dsRNA mediated gene modulation requires sense pRNA. Both processes were accompanied with congruent changes in the methylation pattern of activating and repressive histones.
  
  
  CONCLUSIONS
  Thus this data identifies and demonstrates the role of previously unknown important regulatory transcripts in HPV18 gene expression which can prove valuable targets in cervical cancer therapeutics. This mode of gene regulation by bidirectional transcription could be operational in other promoters as well and serve as a mechanism of regulating gene expression.
authors.affiliation: Department of Biochemistry, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India.
authors.forename: Muzaffer Ahmad
authors.initials: MA
authors.lastname: Kassab
authors.affiliation: Department of Biochemistry, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India.
authors.forename: Madeeha
authors.initials: M
authors.lastname: Mudassir
authors.affiliation: Department of Pathology & Laboratory Medicine, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, United States of America.
authors.forename: Anand
authors.initials: A
authors.lastname: Singh
authors.affiliation: Department of Biochemistry, Institute of Liver and Biliary Sciences, New Delhi, Vasant Kunj, India.
authors.forename: Muthuraman
authors.initials: M
authors.lastname: N
authors.affiliation: Department of Biochemistry, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India.
authors.forename: Mohita
authors.initials: M
authors.lastname: Bhagat
authors.affiliation: Department of Biochemistry, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India.
authors.forename: Jayanth Kumar
authors.initials: JK
authors.lastname: Palanichamy
authors.affiliation: Weill Cornell Medical College, York Avenue, New York, NY, United States of America.
authors.forename: Pradeep
authors.initials: P
authors.lastname: Ramalingam
authors.affiliation: Department of Biochemistry, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India.
authors.forename: Kunzang
authors.initials: K
authors.lastname: Chosdol
authors.affiliation: National Brain Research Center, Manesar, Gurgaon, Haryana, India.
authors.forename: Subrata
authors.initials: S
authors.lastname: Sinha
authors.affiliation: Department of Biochemistry, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India.
authors.forename: Parthaprasad
authors.initials: P
authors.lastname: Chattopadhyay
mesh_terms: D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D044127:Epigenesis, Genetic; D020868:Gene Silencing; D006367:HeLa Cells; D052161:Human papillomavirus 18 / Q000235:genetics*; D006801:Humans; D016376:Oligonucleotides, Antisense / Q000378:metabolism; D009856:Oncogene Proteins, Viral / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012330:RNA, Double-Stranded / Q000032:analysis / Q000378:metabolism*; D022661:RNA, Untranslated / Q000037:antagonists & inhibitors / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D014775:Virus Activation / Q000235:genetics*
chemical_list: D004268:DNA-Binding Proteins; C052603:E6 protein, Human papillomavirus type 18; C052633:E7 protein, Human papillomavirus type 18; D016376:Oligonucleotides, Antisense; D009856:Oncogene Proteins, Viral; D012330:RNA, Double-Stranded; D022661:RNA, Untranslated