Abstract
Helix-loop-helix transcription (HLH) factors regulate several stages of neuronal development including differentiation of individual populations of neurons and neurite growth. Here we demonstrate that axonal injury of corticospinal and dorsal root ganglion neurons induces changes in the expression of several HLH transcription factors that function as negative regulators of neurogenesis and neurite outgrowth. However, the expression of HLH transcription factors that stimulate neurogenesis is not affected by the axonal injury. Expression of HES, SHARP and Id family members is suppressed shortly after axonal injury and expression returns to normal levels after 14 days. We hypothesize that down-regulation of these HLH transcription factors is required for initiation of regenerative response to axonal injury.
MeSH terms
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Animals
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Basic Helix-Loop-Helix Transcription Factors
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DNA-Binding Proteins / genetics
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Down-Regulation / physiology
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Female
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Gene Expression / physiology
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Helix-Loop-Helix Motifs / genetics*
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Homeodomain Proteins / genetics
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Inhibitor of Differentiation Protein 1
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Inhibitor of Differentiation Protein 2
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Nerve Regeneration / physiology*
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Neurites / physiology
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Neurons / physiology*
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Neurons / ultrastructure
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Pyramidal Tracts / cytology
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Pyramidal Tracts / physiology
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Rats
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Rats, Sprague-Dawley
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Repressor Proteins / genetics*
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Sciatic Nerve / cytology
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Sciatic Nerve / physiology
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Transcription Factors / genetics
Substances
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Basic Helix-Loop-Helix Transcription Factors
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Bhlhe40 protein, rat
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Bhlhe41 protein, rat
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DNA-Binding Proteins
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Hairy, HRT1 protein
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Hes5 protein, rat
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Homeodomain Proteins
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ID1 protein, rat
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Id2 protein, rat
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Inhibitor of Differentiation Protein 1
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Inhibitor of Differentiation Protein 2
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Repressor Proteins
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Transcription Factors
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HES5 protein, human