Bax inhibitor-1 enhances survival and neuronal differentiation of embryonic stem cells via differential regulation of mitogen-activated protein kinases activities.
Bax inhibitor-1 (BI-1), a member of the BI-1 family of integral membrane proteins, was originally identified as an inhibitor of stress-induced cell death in mammalian cells. Previous studies have shown that the withdrawal of leukemia inhibitory factor (LIF) results in differentiation of the majority of mouse embryonic stem (mES) cells into various cell lineages, while some ES cells die within 3days. Thus, to investigate the function of BI-1 in ES cell survival and neuronal differentiation, we generated mES cell lines that overexpress BI-1 or a carboxy-terminal BI-1ΔC mutant. Overexpression of BI-1 in mES cells significantly increased cell viability and resistance to apoptosis induced by LIF withdrawal, while the control vector or BI-1ΔC-overexpressing mES cells had no effect. Moreover, overexpression of BI-1 produced significant inhibition of the p38 mitogen-activated protein kinases (MAPK) pathway in response to LIF withdrawal, while activity of the extracellular signal-regulated kinase (ERK)/c-Jun N-terminal kinase (JNK) MAPK pathway was increased. Interestingly, we found that BI-1-overexpressing cells showed higher expression levels of neuroectodermal markers (Otx1, Lmx1b, En1, Pax2, Wnt1, Sox1, and Nestin) and greater neuronal differentiation efficiency than control or BI-1ΔC-overexpressing mES cells did. Considering these findings, our results indicated that BI-1-modulated MAPK activity plays a key role in protecting mES cells from LIF-withdrawal-induced apoptosis and in promoting their differentiation toward neuronal lineages.
Department of Animal Biotechnology (BK21), Animal Resources Research Center, and SMART-IABS, Konkuk University, Seoul 143-702, Republic of Korea.
Kilsoo
K
Jeon
Hyejin
H
Lim
Jung-Hyun
JH
Kim
Dawoon
D
Han
Eung-Ryoung
ER
Lee
Gwang-Mo
GM
Yang
Min-Kyoung
MK
Song
Jin-Hoi
JH
Kim
Ssang-Goo
SG
Cho
D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002454:Cell Differentiation; D049109:Cell Proliferation; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000378:metabolism; D005434:Flow Cytometry; D007124:Immunoenzyme Techniques; D053605:Leukemia Inhibitory Factor / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
D053605:Leukemia Inhibitory Factor; D008565:Membrane Proteins; D012333:RNA, Messenger; C490015:Tmbim6 protein, mouse; D020928:Mitogen-Activated Protein Kinases