The Sonic Hedgehog Pathway Mediates Carbamylated Erythropoietin-enhanced Proliferation and Differentiation of Adult Neural Progenitor Cells

Abstract

Carbamylated erythropoietin (CEPO), a well characterized erythropoietin (EPO) derivative, does not bind to the classical EPO receptor and does not stimulate erythropoiesis. Using neural progenitor cells derived from the subventricular zone of the adult mouse, we investigated the effect of CEPO on neurogenesis and the associated signaling pathways in vitro. We found that CEPO significantly increased neural progenitor cell proliferation and promoted neural progenitor cell differentiation into neurons, which was associated with up-regulation of Sonic hedgehog (Shh), its receptor ptc, and mammalian achaete-scute homolog 1 (Mash1), a pro-neuron basic helix-loop-helix protein transcription factor. Blockage of the Shh signaling pathway with a pharmacological inhibitor, cyclopamine, abolished the CEPOinduced neurogenesis. Attenuation of endogenous Mash1 expression by short-interfering RNA blocked CEPO-promoted neuronal differentiation. In addition, recombinant mouse Shh up-regulated Mash1 expression in neural progenitor cells. These results demonstrate that the Shh signaling pathway mediates CEPO-enhanced neurogenesis and Mash1 is a downstream target of the Shh signaling pathway that regulates CEPO-enhanced neuronal differentiation.

Essential role for Stat5 in the neurotrophic but not in the neuroprotective effect of erythropoietin

“…[6][7][8]11,24 EPO stimulates neurogenesis in vivo and facilitates neuronal differentiation in neuroblastoma cell lines and neural stem cell cultures. 8,11,12,36,37 In regard to the findings with GH, our data agree with a previous report demonstrating reduced brain size and sparser dendritic arborization in GH receptor-deficient (GHR À/À ) mice. 38 Neurite initiation and sprouting were significantly increased in Stat5 À/À neurons as compared to Stat5 þ / þ cells, suggesting that Stat5 activity might negatively regulate neurite outgrowth.…”

Therapeutic Potential of Erythropoietin and its Structural or Functional Variants in the Nervous System

“…36 -38 In contrast, CEPO stimulates adult neurogenesis in the EPOR-knock-out mice suggesting that the cellular signaling by CEPO does not involve the classical EPOR. 38 Future studies are still needed to clarify whether the classical EPOR, the proposed heteromer or another yet unidentified brain specific EPOR mediate the actions of EPO and its structural variants on brain cells.…”

The neuroprotective and neurorescue effects of carbamylated erythropoietin Fc fusion protein (CEPO-Fc) in a rat model of Parkinson’s disease

“…In addition to exerting an anti-apoptotic effect, CEPO may induce Sonic hedgehog (SHH), a mitogen known to enhance neurogenesis and neuroprotection (Amankulor et al, 2009;Wu et al, 2010;Wang et al, 2007). It is possible that SHH is also related to neurotrophins, since BDNF up-regulation was mutually linked to elevated levels of SHH (Hashimoto et al, 2008).…”

“…It is possible that SHH is also related to neurotrophins, since BDNF up-regulation was mutually linked to elevated levels of SHH (Hashimoto et al, 2008). In fact, SHH is responsible for mediating CEPO's effects on the proliferation and differentiation of neural progenitor cells, which explains its beneficial effects in the CNS (Ahn et al, 2005;Amankulor et al, 2009;Wu et al, 2010;Wang et al, 2007). Bouzat et al (2011) Besides its important effects on the SHH pathway, CEPO might exert its beneficial effects on nerve cells through its action on MHC-I (major histocompatibility complex type I) molecules.…”