Linked Life Data

18039974

Source:http://linkedlifedata.com/resource/pubmed/id/18039974

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
24
pubmed:dateCreated
2007-11-27
pubmed:abstractText
Class III semaphorins (SemaIIIs) are intercellular cues secreted by surrounding tissues to guide migrating cells and axons in the developing organism. This chemotropic activity is crucial for the formation of nerves and vasculature. Intriguingly, SemaIIIs are also synthesized by neurons during axon pathfinding, but their function as intrinsic cues remains unknown. We have explored the role of Sema3A expression in motoneurons during spinal nerve development. Loss- and gain-of-function in the neural tube of the chick embryo were undertaken to target Sema3A expression in motoneurons while preserving Sema3A sources localized in peripheral tissues, known to provide important repulsive information for delineating the routes of motor axons towards their ventral or dorsal targets. Strikingly, Sema3A overexpression induced defasciculation and exuberant growth of motor axon projections into these normally non-permissive territories. Moreover, knockdown studies showed that motoneuronal Sema3A is required for correct spinal nerve compaction and dorsal motor axon extension. Further analysis of Sema3A gain- and loss-of-function in ex vivo models revealed that Sema3A in motoneurons sets the level of sensitivity of their growth cones to exogenous Sema3A exposure. This regulation is associated with post-transcriptional and local control of the availability of the Sema3A receptor neuropilin 1 at the growth cone surface. Thus, by modulating the strength of Sema3A-mediated environmental repulsive constraints, Sema3A in motoneurons enables axons to extend more or less far away from these repulsive sources. Such interplay between intrinsic and extrinsic Sema3A may represent a fundamental mechanism in the accurate specification of axon pathways.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0950-1991
pubmed:author
pubmed:issnType
Print
pubmed:volume
134
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
4491-501
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Semaphorin and neuropilin co-expression in motoneurons sets axon sensitivity to environmental semaphorin sources during motor axon pathfinding.
pubmed:affiliation
Université de Lyon, F-69003, France.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't