Wnt7A identifies embryonic γ-motor neurons and reveals early postnatal dependence of γ-motor neurons on a muscle spindle-derived signal Journal Article

   

Authors:	Ashrafi, S.; Lalancette-Hébert, M.; Friese, A.; Sigrist, M.; Arber, S.; Shneider, N. A.; Kaltschmidt, J. A.
Article Title:	Wnt7A identifies embryonic γ-motor neurons and reveals early postnatal dependence of γ-motor neurons on a muscle spindle-derived signal
Abstract:	Motor pools comprise a heterogeneous population of motor neurons that innervate distinct intramuscular targets. While the organization of motor neurons into motor pools has been well described, the time course and mechanism of motor pool diversification into functionally distinct classes remains unclear. γ-Motor neurons (γ-MNs) and α-motor neurons (α-MNs) differ in size, molecular identity, synaptic input and peripheral target. While α-MNs innervate extrafusal skeletal muscle fibers to mediate muscle contraction, γ-MNs innervate intrafusal fibers of the muscle spindle, and regulate sensitivity of the muscle spindle in response to stretch. In this study, we find that the secreted signaling molecule Wnt7a is selectively expressed in γ-MNs in the mouse spinal cord by embryonic day 17.5 and continues to molecularly distinguish γ-from α-MNs into the third postnatal week. Our data demonstrate that Wnt7a is the earliest known γ-MN marker, supporting a model of developmental divergence between α- and γ-MNs at embryonic stages. Furthermore, using Wnt7a expression as an early marker of γ-MN identity, we demonstrate a previously unknown dependence of γ-MNs on a muscle spindle-derived, GDNF-independent signal during the first postnatal week. © 2012 the authors.
Keywords:	immunohistochemistry; signal transduction; controlled study; protein expression; nonhuman; animal cell; mouse; animal tissue; embryo; beta galactosidase; histochemistry; nerve cell differentiation; alpha nerve fiber; gamma motoneuron; muscle spindle; postnatal development; glial cell line derived neurotrophic factor; wnt7a protein
Journal Title:	The Journal of Neuroscience
Volume:	32
Issue:	25
ISSN:	0270-6474
Publisher:	Society for Neuroscience
Date Published:	2012-06-20
Start Page:	8725
End Page:	8731
Language:	English
DOI:	10.1523/jneurosci.1160-12.2012
PROVIDER:	scopus
PUBMED:	22723712
PMCID:	PMC3496251
DOI/URL:	http://www.scopus.com/inward/record.url?eid=2-s2.0-84862834316&partnerID=40&md5=47cea15e8f9986bde0f54249c44bd4d5
Notes:	--- - "Export Date: 1 August 2012" - "CODEN: JNRSD" - "Source: Scopus"

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