Journal of Neuroscience, Vol 13, 5164-5171, Copyright © 1993 by Society for Neuroscience
Cloning and differentiation-induced expression of a murine serotonin1A receptor in a septal cell line
A Charest, BH Wainer and PR Albert
Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada.
A neuronal cell model endogenously expressing the 5-HT1A receptor, in which
to study the function and regulation of this gene, has yet to be
identified. We examined murine SN-48 cells, a septum x neuroblastoma fusion
cell line that proliferates in a nondifferentiated state but can be induced
to differentiate into neurofilament-positive cells following 24-96 hr
treatment with 10 microM retinoic acid in low serum. Northern blot analysis
demonstrated the presence of a single 10.9 kilobase (kb) 5-HT1A receptor
RNA species in differentiated SN-48 cells, which was not detected in
undifferentiated SN-48 cells. The presence of receptor RNA in
differentiated SN-48 cells correlated with the appearance of functional
responses (i.e., pertussis toxin-sensitive inhibition of cAMP accumulation)
to 5-HT1A agonists in differentiated but not in undifferentiated cells. In
order to verify that the large 10.9 kb RNA species in SN-48 cells truly
corresponded to the mouse 5-HT1A receptor RNA, a cDNA fragment from
differentiated SN-48 cells was used to clone the corresponding mouse brain
cDNA. The 2.4 kb cDNA contained a single open reading frame that displayed
high (> 85% predicted amino acid identity) homology to the human and rat
5-HT1A receptor genes. When transfected into receptor-negative Ltk- cells,
this cDNA was found to direct expression of a murine 5-HT1A receptor. Thus,
we conclude that upon differentiation SN-48 cells express RNA encoding
functional 5-HT1A receptors. The SN-48 septal cells will provide a useful
cellular model system for investigating aspects of neuronal differentiation
leading to the development of sensitivity to serotonergic input.
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