The Journal of Neuroscience, January 17, 2007, 27(3):634-644; doi:10.1523/JNEUROSCI.4947-06.2007
Previous Article | Next Article 
Development/Plasticity/Repair
Astrocyte and Muscle-Derived Secreted Factors Differentially Regulate Motoneuron Survival
Anna R. Taylor,1
David J. Gifondorwa,2
Jason M. Newbern,1
Mac B. Robinson,1
Jane L. Strupe,1
David Prevette,1
Ronald W. Oppenheim,1,2 and
Carolanne E. Milligan1,2
1Department of Neurobiology and Anatomy, and 2Program in Neuroscience, Wake Forest University School of Medicine, WinstonSalem, North Carolina 27157
Correspondence should be addressed to Carol E. Milligan, Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, WinstonSalem, NC 27157. Email: milligan{at}wfubmc.edu
During development, motoneurons (MNs) undergo a highly stereotyped, temporally and spatially defined period of programmed cell death (PCD), the result of which is the loss of 4050% of the original neuronal population. Those MNs that survive are thought to reflect the successful acquisition of limiting amounts of trophic factors from the target. In contrast, maturation of MNs limits the need for target-derived trophic factors, because axotomy of these neurons in adulthood results in minimal neuronal loss. It is unclear whether MNs lose their need for trophic factors altogether or whether, instead, they come to rely on other cell types for nourishment. Astrocytes are known to supply trophic factors to a variety of neuronal populations and thus may nourish MNs in the absence of target-derived factors. We investigated the survival-promoting activities of muscle- and astrocyte-derived secreted factors and found that astrocyte-conditioned media (ACM) was able to save substantially more motoneurons in vitro than muscle-conditioned media (MCM). Our results indicate that both ACM and MCM are significant sources of MN trophic support in vitro and in ovo, but only ACM can rescue MNs after unilateral limb bud removal. Furthermore, we provide evidence suggesting that MCM facilitates the death of a subpopulation of MNs in a p75NTR - and caspase-dependent manner; however, maturation in ACM results in MN trophic independence and reduced vulnerability to this negative, pro-apoptotic influence from the target.
Key words: p75NTR; programmed cell death; amyotrophic lateral sclerosis; apoptosis; caspase; SMA; trophic
Received Sept. 11, 2006;
revised Nov. 14, 2006;
accepted Dec. 11, 2006.
Correspondence should be addressed to Carol E. Milligan, Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, WinstonSalem, NC 27157. Email: milligan{at}wfubmc.edu
This article has been cited by other articles:

|
 |

|
 |
 
S. L. Gibb, W. Boston-Howes, Z. S. Lavina, S. Gustincich, R. H. Brown Jr., P. Pasinelli, and D. Trotti
A Caspase-3-cleaved Fragment of the Glial Glutamate Transporter EAAT2 Is Sumoylated and Targeted to Promyelocytic Leukemia Nuclear Bodies in Mutant SOD1-linked Amyotrophic Lateral Sclerosis
J. Biol. Chem.,
November 2, 2007;
282(44):
32480 - 32490.
[Abstract]
[Full Text]
[PDF]
|
 |
|