The SUMO conjugating enzyme Ubc9 is required for inducing and maintaining stem cell pluripotency.
Sumoylation adds a small ubiquitin-like modifier (SUMO) polypeptide to the ε-amino group of a lysine residue. Reminiscent of ubiquitination, sumoylation is catalyzed by an enzymatic cascade composed of E1, E2, and E3. For sumoylation, this cascade uses Ubc9 (ubiquitin conjugating enzyme 9, now officially named ubiquitin conjugating enzyme E2I [UBE2I]) as the sole E2 enzyme. Here, we report that expression of endogenous Ubc9 increases during reprogramming of mouse embryonic fibroblasts (MEFs) into induced pluripotent stem (iPS) cells. In addition, this E2 enzyme is required for reprogramming as its suppression dramatically inhibits iPS cell induction. While Ubc9 knockdown does not affect survival of MEFs and immortalized fibroblasts, Ubc9 is essential for embryonic stem cell (ESC) survival. In addition, we have found that Ubc9 knockdown stimulates apoptosis in ESCs but not in MEFs. Furthermore, the knockdown decreases the expression of the well-known pluripotency marker Nanog and the classical reprogramming factors Klf4, Oct4, and Sox2 in ESCs. Together, these observations indicate that while dispensable for fibroblast survival, the sole SUMO E2 enzyme Ubc9 plays a critical role in reprogramming fibroblasts to iPS cells and maintaining ESC pluripotency.
The Rosalind & Morris Goodman Cancer Research Center, Montréal, Québec, Canada; Department of Anatomy & Cell Biology, Montréal, Québec, Canada.
Soroush
S
Tahmasebi
Mohammad
M
Ghorbani
Paul
P
Savage
Goran
G
Gocevski
Xiang-Jiao
XJ
Yang
D000818:Animals; D000943:Antigens, Differentiation / Q000378:metabolism*; D002460:Cell Line; D002470:Cell Survival; D065150:Cellular Reprogramming; D053595:Embryonic Stem Cells / Q000166:cytology / Q000201:enzymology*; D005347:Fibroblasts / Q000166:cytology / Q000201:enzymology; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000166:cytology / Q000201:enzymology*; D000090062:Kruppel-Like Factor 4; D051379:Mice; D044763:Ubiquitin-Conjugating Enzymes / Q000235:genetics / Q000378:metabolism*; D000098843:Ubiquitin-Conjugating Enzyme UBC9
D000943:Antigens, Differentiation; C000715467:KLF4 protein, human; C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; D044763:Ubiquitin-Conjugating Enzymes; D000098843:Ubiquitin-Conjugating Enzyme UBC9
Embryonic stem cells; Induced pluripotent stem cells; Reprogramming; Sumoylation; Ubiquitin conjugating enzyme 9