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Retinoid signaling and the generation of regional and cellular diversity in the embryonic mouse spinal cord
Author(s) -
Colbert Melissa C.,
Rubin William W.,
Linney Elwood,
LaMantia AnthonySamuel
Publication year - 1995
Publication title -
developmental dynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.634
H-Index - 141
eISSN - 1097-0177
pISSN - 1058-8388
DOI - 10.1002/aja.1002040102
Subject(s) - biology , embryonic stem cell , microbiology and biotechnology , spinal cord , diversity (politics) , retinoid , embryogenesis , embryo , anatomy , retinoic acid , neuroscience , genetics , gene , sociology , anthropology
Abstract Retinoid‐dependent gene expression accompanies the emergence of distinct regions and cell classes in the mouse spinal cord around midgestation. We asked whether changes in the expression of retinoid signaling molecules and retinoid‐responsive genes reflect the establishment of this regional and cellular diversity. At E10.5, retinoic acid (RA) receptors (RAR)α, RARβ, the retinoid X receptor (RXR)γ, cellular RA binding protein (CRABP)I, CRAPBII, and cellular retinol binding protein (CRBP)I mRNAs are found throughout the entire anterior‐posterior (AP) axis of the cord, as is RA (Colbert et al. [1993] Proc. Natl. Acad. Sci. U.S.A. 90:6572–6576) and RA‐sensitive transgene expression (Balkan et al. [1992] Proc. Natl. Acad. Sci. U.S.A. 89:3347–3351). At E12.5, RA, transgene expression, and RARβ become restricted to the cervical and lumbar cord. RARα, CRABPI, and RXRγ, however, are found throughout the AP extent. CRABPII and CRBPI, although expanded within the cervical and lumbar regions, are also found throughout the AP axis. Thus, several retinoid signaling molecules continue to be expressed beyond distinct regions of the spinal cord where RA is available and some RA‐responsive genes are either restricted or enhanced. Exogenous RA can activate a more widespread response resulting in ectopic transgene and RARβ expression in the thoracic and sacral cord. Not all RA‐sensitive genes, however, respond; CRABPII and CRBPI expression patterns are unchanged. Finally, not every cell within the normal or exogenously induced domains of RA‐dependent gene expression responds to RA, nor does every cell express RA receptors or binding proteins. Thus, regional and cellular differences in the distribution of the known retinoid receptors and binding proteins do not predict absolutely where or whether retinoid sensitive genes will be expressed or where retinoids will be available in the developing spinal cord. Instead, retinoid‐mediated gene expression in the cervical and lumbar cord seems to reflect retinoid responses that rely both on the local availability of retinoids, the identity of the responding gene, and an indeterminate array of retinoid signaling molecules. © 1995 wiley‐Liss, Inc.