Early Acquisition of Typical Metabolic Features upon Differentiation of Mouse Neural Stem Cells into Astrocytes J.F. BRUNET, 1,2 * L. GROLLIMUND, 1 J-Y. CHATTON, 2 S. LENGACHER, 2 P.J. MAGISTRETTI, 2 J.G. VILLEMURE, 1 AND L. PELLERIN 2 1 Service of Neurosurgery, CHUV, Lausanne, Switzerland 2 Institute of Physiology, Lausanne, Switzerland KEY WORDS gliogenesis; brain energy metabolism; glutamate transport; leukemia inhibitory factor ABSTRACT Specific metabolic features, such as glutamate reuptake, have been associated with normal functions of mature astrocytes. In this study, we examined whether these characteristics are acquired together with classical phenotypic markers of differentiated astrocytes. Differentiation of E14 mouse neurospheres into astrocytes was induced by the addition of fetal bovine serum (FBS). Degree of differentiation was assessed by reverse transcription-polymerase chain reaction (RT-PCR) and immunoflu- orescence for both GFAP and nestin. Neural stem cells expressed nestin but not GFAP, while differentiated astrocytes were immunopositive for GFAP but displayed low levels of nestin expression. A strong increase in the expression of the glutamate transporter GLAST and the monocarboxylate transporter MCT1 accompanied phenotypic changes. In addition, active glutamate transport appeared in differentiated astrocytes, as well as their capacity to increase aerobic glycolysis in response to glutamate. Leukemia inhib- itory factor (LIF) and ciliary neurotrophic factor, but not interleukin-6, triggered the expression of phenotypic and morphological characteristics of astrocytes. In addition, exposure to LIF led to the appearance of metabolic features typically associated with astrocytes. Altogether, our results show that acquisition of some specific metabolic features by astrocytes occurs early in their differentiation process and that LIF repre- sents a candidate signal to induce their expression. © 2003 Wiley-Liss, Inc. INTRODUCTION Understanding how different cell types are gener- ated during development and evolve to acquire their mature phenotype is a fundamental question of biol- ogy. In the central nervous system, it was observed that cells arise in a sequential manner, with neurogen- esis preceding gliogenesis, and by a progressive restric- tion in development potential of precursor cells (Lee et al., 2000; Sauvageot and Stiles, 2002). Gliogenesis, or the generation of astrocytes and oligodendrocytes dur- ing development, has recently attracted much atten- tion. A complex set of cell-intrinsic factors and environ- mental cues are responsible for determining cell fate. The molecular mechanisms involved in these processes are slowly coming to light. The in vitro use of multipo- tent stem cells isolated from animals at different stages of development has been extremely useful in under- standing the process at work (Weiss et al., 1996; Bar- tlett et al., 1998). Thus, it was shown that multipotent stem cells isolated from rodent embryos at different Grant sponsor: Fonds National de la Recherche Scientifique (FNRS); Grant number: 3200-059139.99; Grant sponsor: Foundation LEENAARDS; Grant sponsor: Neurosurgery Department, Lausanne University Hospital. *Correspondence to: Jean-Franc ¸ois Brunet, Institute of Physiology, Bugnon 7, CH-1005 Lausanne, Switzerland. E-mail: jean-francois.brunet@chuv.hospvd.ch Received 14 August 2003; Accepted 26 September 2003 DOI 10.1002/glia.10348 GLIA 46:8 –17 (2004) © 2003 Wiley-Liss, Inc.