EPO receptor-mediated ERK kinase and NF-κB activation in erythropoietin-promoted differentiation of astrocytes

doi:10.1016/j.bbrc.2004.06.060

Biochemical and Biophysical Research Communications

Volume 320, Issue 4, 6 August 2004, Pages 1087-1095

https://doi.org/10.1016/j.bbrc.2004.06.060 Get rights and content

Abstract

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 (0.1–10 U/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-κB during morphological differentiation of astrocytes. Concomitant with the progression of the morphological differentiation of astrocytes, ERK₂ but not JNK₁ and p38 MAPK as well as NF-κB were activated. However, in the presence of PD98,059, an inhibitor of ERK, and salicylic acid, an NF-κB 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 ERK₂ and NF-κB 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-κB pathway.

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Materials and methods

Astrocyte culture and treatment. The Sprague–Dawley rats were maintained in accordance with the policy of the National Institute of Toxicological Research, which is in accord with the Korea Food and Drug Administration’s guideline for the care and use of laboratory animals. Sprague–Dawley rats weighing 200–300 g were housed under 12 h light/dark cycle, at 23 °C and 60 ± 5% humidity. All animals had free access to food (Samyang Foods, Seoul, Korea) and water. Cerebral cortical cells were isolated

EPO receptor mediated astrocyte differentiation

Exposure of EPO (5 U/ml) for 1, 3, 5, 7 days to 2-day-old cultured neuronal stem cells resulted in a marked promotion of morphological differentiation into astrocytes (Fig. 1A). This effect was dose dependent (1–10 U/ml, data not shown). Consistent morphological differentiation, immunohistochemical and Western blotting analysis using anti-GFAP antibody also revealed that EPO increased the number of GFAP-positive cells and expression of GFAP compared with untreated cells (Figs. 1B and C). The

Discussion

During the CNS development, neuronal stem cells are proliferated in an appropriate number and then differentiated into neuron and glial cells. These sequential events of stem cell proliferation and neurogenesis and gliogenesis resulted in being well established before the other system development [26]. Several signals and mechanisms are involved in the morphological change of astrocytes toward differentiation during neuronal tissue development and pathological conditions [27], [28]. We

Acknowledgements

This work was supported by the Korean Research Foundation Grant (KRF-2001-005-E22001) and was also supported by the Brain Korea 21 Project in 2003.

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The spatial and temporal distribution of the activated ERK1/2 is of great importance for both Purkinje and granule cells differentiate into mature stage. Interestingly, in primary cultures of cortical neuronal stem cells isolated from the post neonatal (Day 1) rat brain, erythropoietin (EPO) stimulates differentiation of neuronal stem cells into astrocytes in an EPO receptor dependent manner and this EPO receptor mediated stimulation may be associated with the activation of ERK kinase and NF-κB pathway (Lee et al., 2004). Furthermore, the involvement of carbachol-induced ERK1/2 activation has been demonstrated in the activation of M1 muscarinic receptor signaling that induces neuronal differentiation in pyramidal hippocampal neurons (VanDeMark et al., 2009).
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EPO receptor-mediated ERK kinase and NF-κB activation in erythropoietin-promoted differentiation of astrocytes

Abstract

Section snippets

Materials and methods

EPO receptor mediated astrocyte differentiation

Discussion

Acknowledgements

Blood

FEBS Lett

J. Pediatr

Early Hum. Dev

Brain Res

Eur. J. Pharmacol

Neurosci. Lett

Life Sci

Brain Res

Brain Res. Mol. Brain Res

Mol. Cell. Neurosci

Exp. Cell. Res

Neuron

Mol. Cell. Neurosci

Neurosci. Res

J. Biol. Chem

Exp. Cell. Res

J. Neuroimmunol

Erythropoietic, neurotrophic, and angiogenic functions of erythropoietin and regulation of erythropoietin production (review)

Int. J. Hematol

Role of the kidney in erythropoiesis

Nature

Localization of specific erythropoietin binding sites in defined areas of the mouse brain

Proc. Natl. Acad. Sci. USA