EPO receptor-mediated ERK kinase and NF-kappaB activation in erythropoietin-promoted differentiation of astrocytes.
Erythropoietin (EPO), a hematopoietic factor, is also required for normal brain development, and its receptor is localized in brain. Therefore, it is possible that EPO could act as a neurotropic factor inducing differentiation of neurons. In the present study, we investigated whether EPO can promote differentiation of neuronal stem cells into astrocytes. In primary culture of cortical neuronal stem cells isolated from post neonatal (Day 1) rat brain, EPO dose (0.1-10U/ml) dependently promoted initiation of morphological differentiation of astrocyte and expression of an astrocyte marker protein, glial fibrillary acidic protein (GFAP). Expression of EPO receptor was also increased during morphological differentiation of astrocytes. EPO-induced increased morphological differentiation of astrocytes and GFAP expression were reduced by treatment with anti-EPO and EPO receptor antibodies. Since our previous study showed that activation of MAPK family and transcription factors is differentially involved in neuronal cell differentiation, we further determined the activation of MAP kinase family and NF-kappaB during morphological differentiation of astrocytes. Concomitant with the progression of the morphological differentiation of astrocytes, ERK(2) but not JNK(1) and p38 MAPK as well as NF-kappaB were activated. However, in the presence of PD98,059, an inhibitor of ERK, and salicylic acid, an NF-kappaB inhibitor, the EPO-induced morphological differentiation of astrocytes and expression of FGAP and EPO receptor were reduced. Conversely, treatment with anti-EPO and EPO receptor antibodies also reduced EPO-induced ERK(2) and NF-kappaB activation. These data demonstrate that EPO can promote differentiation of neuronal stem cells into astrocytes in an EPO receptor dependent manner, and this effect may be associated with the activation of ERK kinase and NF-kappaB pathway.
Lee
Sang Min
SM
College of Pharmacy, Chungbuk National University, 48, Gaesin-dong, Heungduk-gu, Cheongju, Chungbuk 361-763, Republic of Korea.
Nguyen
Thi Hong Nga
TH
Park
Mi Hee
MH
Kim
Kyung Soon
KS
Cho
Kyoung Joo
KJ
Moon
Dong Cheul
DC
Kim
Hak Yong
HY
Yoon
Do Young
DY
Hong
Jin Tae
JT
D000818:Animals; D001253:Astrocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004921:Erythropoietin / Q000494:pharmacology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017467:Receptors, Erythropoietin / Q000378:metabolism*; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
D016328:NF-kappa B; D017467:Receptors, Erythropoietin; D004921:Erythropoietin; D020928:Mitogen-Activated Protein Kinases