MBD6 is a direct target of Oct4 and controls the stemness and differentiation of adipose tissue-derived stem cells.
Argonaute 2 (Ago2) is a pivotal regulator of cell fate in adult stem cells. Its expression is significantly downregulated in late passages of cells, concomitant with a prominent increase in Ago2 cytosolic localization in single cells. Nuclear localization of Ago2 is crucial for the survival, proliferation, and differentiation of hATSCs (human adipose tissue-derived stem cells), mediated by the specific binding of the regulatory regions of functional genes, which positively or negatively altered gene expression. Ago2 targets genes that control stemness, reactive oxygen species scavenging, and microRNA expression, all of which are crucial for hATSC survival and self-renewal. Ago2 promotes cell proliferation and self-renewal by activating the expression of octamer-binding transcription factor 4 (Oct4). We confirmed the direct regulation of Oct4 activity by Ago2, as indicated by the results of the ChIP analysis. Methyl-CpG-binding protein 6 (MBD6) was detected as an Oct4 regulatory gene. As predicted, knockdown of MBD6 expression attenuated cell proliferation and eventually induced cell death. We hypothesized that MBD6 functions downstream of Oct4 in the regulation of stemness-related genes, cell proliferation, self-renewal activity, and survival. MBD6 also promoted cell transdifferentiation into neural and endodermal β-cells while significantly attenuating differentiation into the mesodermal lineage. We demonstrate that MBD6 is regulated by Ago2 via an interaction with Oct4, which alters self-renewal and gene expression in hATSCs. MBD6 was promoted cell proliferation through a novel set of signal mediators that may influence differentiation by repressing MBD2 and MBD3, which are possibly recruited by germ cell nuclear factor (GCNF).
Laboratory of Stem Cell Biology, Department of Biotechnology, College of Veterinary Medicine, Seoul National University, Seoul, 151-742, Republic of Korea.
Jin Sun
JS
Jung
Min Ki
MK
Jee
Hyun Tae
HT
Cho
Jee In
JI
Choi
Young Bin
YB
Im
Oh Hyun
OH
Kwon
Soo Kyung
SK
Kang
D000273:Adipose Tissue / Q000166:cytology*; D000328:Adult; D053687:Adult Stem Cells / Q000166:cytology* / Q000378:metabolism; D060565:Argonaute Proteins / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D005810:Multigene Family; D050814:Octamer Transcription Factor-3 / Q000378:metabolism*; D015854:Up-Regulation
C466422:AGO2 protein, human; D060565:Argonaute Proteins; D004268:DNA-Binding Proteins; C553236:MBD6 protein, human; D050814:Octamer Transcription Factor-3; C494173:POU5F1 protein, human