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Lack of correspondence between mRNA expression for a putative cell death molecule (SGP-2) and neuronal cell death in
G A Garden1, M Bothwell, E W Rubel
1Department of Physiology and Biophysics, University of Washington, Seattle 98195.
Abstract:
Neuronal death during nervous system development, a widely observed phenomenon, occurs through unknown mechanisms. Recent evidence suggests an active, destructive process requiring new gene expression. Sulfated glycoprotein-2 (SGP-2), a secretory product of testicular Sertoli cells has been shown to up-regulate in several nonneural tissues undergoing programmed cell death and in several types of neuronal degeneration. In order to determine if this message up-regulates in neurons undergoing developmentally determined cell death, we have studied the expression of SGP-2 mRNA in the developing and adult rat central nervous system (CNS) with in situ hybridization. We also report on the expression of this message in nonneural tissues from several regions of the developing embryo. The developing and adult rat central nervous system as well as widely varied tissues in the rat embryo express SGP-2 mRNA in a pattern that does not correlate with regions undergoing developmental cell death. In the nervous system, SGP-2 mRNA is expressed in neuronal populations including motor neurons, cortical neurons, and hypothalamic neurons at ages when the period of developmental cell death has passed. In a nonneural tissue (palatal shelve epithelium) for which a developmental cell death period has been described, SGP-2 mRNA was not present in the region where cell death occurs. We conclude that SGP-2 mRNA expression cannot be correlated with programmed cell death in neural or nonneural tissues. The results of this study as well as recently reported SGP-2 homologies indicate a possible role for this protein in secretion and lipid transport.
Insights
Sulfated glycoprotein-2 (SGP-2) mRNA is not correlated with programmed cell death in the developing nervous system or other embryonic tissues. This finding suggests SGP-2 may have roles beyond cell death, possibly in secretion and lipid transport.
Area of Science:
- Neuroscience
- Developmental Biology
- Molecular Biology
Background:
- Neuronal death is a key process in nervous system development, but its mechanisms remain unclear.
- Recent studies suggest programmed cell death involves active gene expression.
- Sulfated glycoprotein-2 (SGP-2) is upregulated in non-neural tissues during programmed cell death and neuronal degeneration.
Purpose of the Study:
- To investigate if SGP-2 mRNA expression correlates with developmentally determined cell death in neurons.
- To examine SGP-2 mRNA expression in neural and non-neural tissues during embryonic development.
Main Methods:
- In situ hybridization was used to study SGP-2 mRNA expression in the developing and adult rat central nervous system (CNS).
- SGP-2 mRNA expression was also analyzed in various tissues of the rat embryo.
Main Results:
- SGP-2 mRNA was expressed in the developing and adult rat CNS, but not in regions undergoing developmental cell death.
- Expression was observed in mature neuronal populations, such as motor and cortical neurons, after the period of cell death.
- In non-neural tissues, such as palatal shelf epithelium, SGP-2 mRNA was absent in areas of known developmental cell death.
Conclusions:
- SGP-2 mRNA expression is not associated with programmed cell death in either neural or non-neural tissues.
- The study suggests SGP-2 may play a role in secretion and lipid transport, based on its expression patterns and known homologies.