Neural stem cells express melatonin receptors and neurotrophic factors: colocalization of the MT sub(1 )receptor with neuronal and glial markers

• Published in: BMC neuroscience 2004-01, Vol.5
• Main Authors: Niles, Lennard P, Armstrong, Kristen J, Rincon Castro, Lyda M, Dao, Chung V, Sharma, Rohita, McMillan, Catherine R, Doering, Laurie C, Kirkham, David L
• Format: Article
• Language: English
• ISSN: 1471-2202
• DOI: 10.1186/1471-2202-5-41

Background: In order to optimize the potential benefits of neural stem cell (NSC) transplantation for the treatment of neurodegenerative disorders, it is necessary to understand their biological characteristics. Although neurotrophin transduction strategies are promising, alternative approaches such as the modulation of intrinsic neurotrophin expression by NSCs, could also be beneficial. Therefore, utilizing the C17.2 neural stem cell line, we have examined the expression of selected neurotrophic factors under different in vitro conditions. In view of recent evidence suggesting a role for the pineal hormone melatonin in vertebrate development, it was also of interest to determine whether its G protein-coupled MT sub(1 )and MT sub(2 )receptors are expressed in NSCs. Results: RT-PCR analysis revealed robust expression of glial cell-line derived neurotrophic factor (GDNF), brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in undifferentiated cells maintained for two days in culture. After one week, differentiating cells continued to exhibit high expression of BDNF and NGF, but GDNF expression was lower or absent, depending on the culture conditions utilized. Melatonin MT sub(1 )receptor mRNA was detected in NSCs maintained for two days in culture, but the MT sub(2 )receptor was not seen. An immature MT sub(1 )receptor of about 30 kDa was detected by western blotting in NSCs cultured for two days, whereas a mature receptor of about 40 -45 kDa was present in cells maintained for longer periods. Immunocytochemical studies demonstrated that the MT sub(1 )receptor is expressed in both neural ( beta -tubulin III positive) and glial (GFAP positive) progenitor cells. An examination of the effects of melatonin on neurotrophin expression revealed that low physiological concentrations of this hormone caused a significant induction of GDNF mRNA expression in NSCs following treatment for 24 hours. Conclusions: The phenotypic characteristics of C17.2 cells suggest that they are a heterogeneous population of NSCs including both neural and glial progenitors, as observed under the cell culture conditions used in this study. These NSCs have an intrinsic ability to express neurotrophic factors, with an apparent suppression of GDNF expression after several days in culture. The detection of melatonin receptors in neural stem/progenitor cells suggests involvement of this pleiotropic hormone in mammalian neurodevelopment. Moreover, the ability of melatonin to i