1. Stress-Induced SP1 and p75NTR Transcription
Alberto Ramos, Wai Chi Ho, Stephanie Forte, Kathleen Dickson, Jacqueline Boutilier, Kristy Favell, and Philip A. Barker
The p75 neurotrophin receptor (p75NTR), normally expressed at low levels in adult tissue, springs to life in times of crisis, such as brain injury, ischemia, and seizures, and facilitates neuronal apoptosis. Ramos et al. this week examined how the stress of cell swelling, induced by hypoosmolarity, triggers p75NTR expression. The authors focused on a proximal promoter region shared by the human, rat, and mouse p75NTR genes. The conserved GC-rich region contained several putative binding sites for the zinc-finger transcription factor Sp1. In human embryonic kidney 293 cells and primary cultures of mouse cortical neurons, p75NTR expression was significantly and reversibly elevated by hypo-osmotic solutions. When Sp1 activity was reduced by overexpression of a dominant-negative Sp1, RNA interference, or inhibitors, the effect on p75NTR was diminished. Six hours of hypotonic solution stabilized the normally rapid degradation of SP1, suggesting that changes in SP1 turnover may regulate p75NTR expression in response to stress.
2. Sexually Dimorphic Brain Development in Infants
John H. Gilmore, Weili Lin, Marcel W. Prastawa, Christopher B. Looney, Y. Sampath K. Vetsa, Rebecca C. Knickmeyer, Dianne D. Evans, J. Keith Smith, Robert M. Hamer, Jeffrey A. Lieberman, and Guido Gerig
This week, Gilmore et al. examined the growth of gray and white matter during the first weeks of life. The authors performed magnetic resonance imaging (MRI) on 74 neonates and created an MRI atlas as a template to estimate gray, white, and CSF volumes. As in children and adults, neonatal male brains were slightly larger than in females, by~9%. Males also had slightly more cortical gray matter, cortical white matter, and subcortical gray matter. Neonates of both sexes had more
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Society for Neuroscience