Functional analysis of Tcl1 using Tcl1-deficient mouse embryonic stem cells.
Tcl1 is highly expressed in embryonic stem (ES) cells, but its expression rapidly decreases following differentiation. To assess Tcl1's roles in ES cells, we generated Tcl1-deficient and -overexpressing mouse ES cell lines. We found that Tcl1 was neither essential nor sufficient for maintaining the undifferentiated state. Tcl1 is reported to activate Akt and to enhance cell proliferation. We found that Tcl1 expression levels correlated positively with the proliferation rate and negatively with the apoptosis of ES cells, but did not affect Akt phosphorylation. On the other hand, the phosphorylation level of β-catenin decreased in response to Tcl1 overexpression. We measured the β-catenin activity using the TOPflash reporter assay, and found that wild-type ES cells had low activity, which Tcl1 overexpression enhanced 1.8-fold. When the canonical Wnt signaling is activated by β-catenin stabilization, it reportedly helps maintain ES cells in the undifferentiated state. We then performed DNA microarray analyses between the Tcl1-deficient and -expressing ES cells. The results revealed that Tcl1 expression downregulated a distinct group of genes, including Ndp52, whose expression is very high in blastocysts but reduced in the primitive ectoderm. Based on these results, we discuss the possible roles of Tcl1 in ES cells.
Division of Stem Cell Regulation Research, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
Tatsushi
T
Miyazaki
Satsuki
S
Miyazaki
Masafumi
M
Ashida
Tomofumi
T
Tanaka
Fumi
F
Tashiro
Jun-ichi
J
Miyazaki
D000818:Animals; D017209:Apoptosis / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics; D002460:Cell Line; D049109:Cell Proliferation; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000502:physiology*; D020869:Gene Expression Profiling; D018014:Gene Transfer Techniques; D051379:Mice; D018345:Mice, Knockout; D046228:Microarray Analysis; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D060449:Wnt Signaling Pathway / Q000235:genetics
D011518:Proto-Oncogene Proteins; C490393:Tcl1 protein, mouse