Transgenic Analyses Reveal Developmentally Regulated Neuron- and Muscle-specific Elements in the Murine Neurofilament Light Chain Gene Promoter*
Abstract
We report here the developmental activity of regulatory elements that reside within 1.7 kilobases of the murine neurofilament light chain (NF-L) gene promoter. NF-L promoter activity is first detected at embryonic day 8.5 in neuroepithelial cells. Neuron-specific gene expression is maintained in the spinal cord until embryonic day 12.5 and at later developmental stages in the brain and sensory neuroepithelia. After day 14.5, the promoter becomes active in myogenic cells. Transgene expression in both neurons and muscle is consistent with the detection of endogenous NF-L transcript in both neuronal and myogenic tissues of neonates by reverse transcriptase-polymerase chain reaction. Neuron- and muscle-specific activities of the NF-L promoter decrease and are nearly undetectable after birth. Thus, the 1.7-kilobase NF-L promoter contains regulatory elements for initiation but not maintenance of transcription from the NF-L locus. Deletion analyses reveal that independent regulatory elements control the observed tissue-specific activities and implicate a potential MyoD binding site as the muscle-specific enhancer. Our results demonstrate that the NF-L promoter contains distinct regulatory elements for both neuron- and muscle-specific gene expression and that these activities are temporally separated during embryogenesis.
Footnotes
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↵* This work was supported in part by a grant from the Arizona Disease Control Research Commission (to C. K.) and by the generous support of the Mayo Foundation.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) U80021.
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↵‡ Present address: Dept. of Biochemistry, Midwestern University, 19555 N. 59th Ave., Glendale, AZ 85308.
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↵§ To whom correspondence should be addressed: S. C. Johnson Medical Research Center, Mayo Clinic Arizona, 13400 E. Shea Blvd., Scottsdale, AZ 85259. Tel.: 602-301-7137; Fax: 602-301-7017; E-mail:ckappen{at}mayo.edu.
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↵1 The abbreviations used are: NF, neurofilament; NF-L, -M, -H, neurofilament light, medium, and heavy chain, respectively; RT-PCR, reverse transcriptase-polymerase chain reaction; dpc, days post-coitum; bp, base pair(s); kb, kilobase(s); PBS, phosphate-buffered saline; X-gal, 5-bromo-4-chloro-3-indolyl β-d-galactopyranoside; IE, immediate early; bHLH, basic-helix-loop-helix; CAT, chloramphenicol acetyltransferase.
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↵2 P. Yaworsky and C. Kappen, unpublished data.
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↵3 M. Vitadello, unpublished data, GenBankTM accession Z47378.
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↵4 J. Lin, S. Pfaff, and T. Jessell, personal communication.
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- Received December 18, 1996.
- Revision received June 13, 1997.
