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IGF‐1 stimulates de novo fatty acid biosynthesis by Schwann cells during myelination
Author(s) -
Liang Guoying,
Cline Gary W.,
Macica Carolyn M.
Publication year - 2007
Publication title -
glia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.954
H-Index - 164
eISSN - 1098-1136
pISSN - 0894-1491
DOI - 10.1002/glia.20496
Subject(s) - biology , myelin , fatty acid synthesis , fatty acid , biochemistry , schwann cell , microbiology and biotechnology , lipid metabolism , diacylglycerol lipase , signal transduction , dorsal root ganglion , diacylglycerol kinase , endocrinology , central nervous system , neuroscience , protein kinase c , sensory system
Schwann cell (SC) differentiation to the myelinating phenotype is characterized by the elaboration of a lipid‐rich membrane and the expression of myelin‐specific proteins. Insulin‐like growth factor‐1 (IGF‐1) has been identified as a growth factor that stimulates the early events of myelination in SCs that signals via the PI3K/Akt pathway. Given the role of IGF‐1 in promoting myelination, we performed studies to determine if the fatty acid biosynthetic pathway was a target of IGF‐1 signaling in the formation of myelin membrane in dorsal root ganglion neuron/Schwann cell (DRG/SC) cocultures. We report that the fatty acid profile of lipid extracts of cocultures treated with IGF‐1 match that reported for native myelin membrane by electrospray mass spectroscopy analysis. We also demonstrate de novo fatty acid biosynthesis in response to IGF‐1 treatment in DRG/SC cocultures metabolically labeled with 13 C‐acetate as a carbon source for fatty acid synthesis. Consistent with this finding, Western blot analysis of lysates from both cocultures and purified SCs reveal that IGF‐1 stimulates two key fatty acid synthesizing enzymes. Additionally, we show that stimulation of fatty acid synthesizing enzymes is mediated by the PI3K/Akt signaling pathway. We also show that the fatty acid synthesizing enzymes and associated signaling pathways are elevated during the period of myelin membrane formation in sciatic nerve. Collectively, these findings demonstrate that IGF‐1 plays an important regulatory function during myelin membrane formation. © 2007 Wiley‐Liss, Inc.