Upregulation of PHLDA2 in Dicer knockdown HEK293 cells.
It has been reported that RNAi-dependent chromatin silencing in vertebrates is not restricted to the centromeres. To address whether RNAi machinery could regulate the chromatin structure of imprinted genes, we knocked down Dicer in HEK293 cells and found that the expression of PHLDA2, one of the several genes in the imprinted gene domain of 11p15.5, was specifically upregulated. This was accompanied by a shift towards more activated chromatin at PHLDA2 locus as indicated by change in H3K9 acetylation, however, the methylation state at this locus was not affected. Furthermore, we found that PHLDA2 was downregulated in growth-arrested HEK293 cells induced by either serum deprivation or contact inhibition. This suggests that PHLDA2 upregulation might be a direct result of Dicer depletion rather than the consequence of growth arrest induced by Dicer knockdown. Considering the reports that there is consistent placental outgrowth in PHLDA2 knockout mice and that PHLDA2 overexpression in mice causes growth inhibition, we speculate that PHLDA2 may be a candidate for contributing to the reduced growth rate of Dicer-deficient cells and the very early embryonic lethality in Dicer knockout mice.
Tang
Kai-Fu
KF
Key Laboratory of Molecular Biology for Infectious Diseases of State Ministry of Education, The second Affiliated Hospital, Institute for Viral Hepatitis, Chongqing University of Medical Sciences, Chongqing 400010, PR China. tangkaifu@hotmail.com
Wang
Yan
Y
Wang
Pengfei
P
Chen
Min
M
Chen
Yao
Y
Hu
Huai-Dong
HD
Hu
Peng
P
Wang
Bo
B
Yang
Wenjie
W
Ren
Hong
H
D018929:Cell Culture Techniques; D002460:Cell Line; D002843:Chromatin / Q000378:metabolism; D003260:Contact Inhibition; D016895:Culture Media, Serum-Free; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism*; D004722:Endoribonucleases / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000235:genetics*; D006801:Humans; D007668:Kidney / Q000166:cytology* / Q000196:embryology; D009687:Nuclear Proteins / Q000502:physiology*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D043244:Ribonuclease III; D014162:Transfection; D015854:Up-Regulation
D002843:Chromatin; D016895:Culture Media, Serum-Free; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; C109277:TSSC3 protein; D004722:Endoribonucleases; C408087:DICER1 protein, human; D043244:Ribonuclease III; D053487:DEAD-box RNA Helicases