Related Experiment Videos
Differential expression and regional distribution of steroid receptor coactivators SRC-1 and SRC-2 in brain and
O C Meijer1, P J Steenbergen, E R De Kloet
1Division of Medical Pharmacology, Leiden/Amsterdam Center for Drug Research, The Netherlands. o.meijer@lacdr.leidenuniv.nl
Abstract:
Members of the p160 family of steroid receptor coactivator proteins mediate the stimulatory effects on gene transcription brought about by nuclear receptors, which comprise all steroid receptors. Using in situ hybridization we have examined the neuroanatomical distribution of the messenger RNAs (mRNAs) for two functionally distinct splice variants of Steroid Receptor Coactivator 1 (SRC-1/NCoA-1) and of Steroid Receptor Coactivator 2 (SRC-2/NCoA-2/GRIP-1/TIF-2). Transcripts encoding these coactivators show highly differential expression patterns. SRC-2 mRNA is expressed at very low levels in brain, but shows expression in the anterior pituitary. SRC-la and le mRNA are expressed in many brain areas, including hippocampus, amygdala, hypothalamus, basal ganglia, and isocortex. Striking differences between SRC-1a and le expression were observed in several brain nuclei. Relative levels of SRC-1a mRNA were much higher in anterior pituitary, and the arcuate, paraventricular and ventromedial nucleus of the hypothalamus, the locus coeruleus and the trigeminal motor nucleus, all important targets of steroid hormones in the brain. SRC-le mRNA showed modest elevation of relative expression in the caudal nucleus accumbens (shell), basolateral amygdala, and some thalamic nuclei. The differential and uneven neuroanatomical distribution of these coactivators may underlie diversity and cell-specificity of steroid receptor mediated signals in the brain.
Insights
Steroid receptor coactivators, Steroid Receptor Coactivator-1a (SRC-1a) and Steroid Receptor Coactivator-1e (SRC-1e), show distinct brain distributions. This differential expression suggests varied roles in steroid hormone signaling within the brain.
Area of Science:
- Neuroscience
- Molecular Biology
- Endocrinology
Background:
- Steroid receptor coactivators (SRCs) are crucial for nuclear receptor-mediated gene transcription.
- The p160 family, including SRC-1 and SRC-2, plays a significant role in this process.
- Understanding the neuroanatomical distribution of SRCs is key to deciphering steroid hormone action in the brain.
Purpose of the Study:
- To investigate the differential neuroanatomical distribution of messenger RNAs (mRNAs) for two splice variants of Steroid Receptor Coactivator 1 (SRC-1a and SRC-1e).
- To examine the expression patterns of Steroid Receptor Coactivator 2 (SRC-2) mRNA in the brain and pituitary.
Main Methods:
- In situ hybridization was employed to visualize and quantify the distribution of SRC-1a, SRC-1e, and SRC-2 mRNAs in the brain and anterior pituitary.
- Comparative analysis of expression levels across various brain regions and nuclei was performed.
Main Results:
- SRC-2 mRNA exhibited very low expression in the brain but was detected in the anterior pituitary.
- SRC-1a and SRC-1e mRNAs were widely expressed in brain areas including the hippocampus, amygdala, hypothalamus, basal ganglia, and isocortex.
- Significant differences in expression were noted between SRC-1a and SRC-1e in specific brain nuclei, with SRC-1a showing higher levels in key steroid hormone target regions.
Conclusions:
- The distinct neuroanatomical distribution patterns of SRC-1a and SRC-1e mRNAs suggest specialized functions in different neuronal populations.
- These differential expression profiles likely contribute to the diversity and cell-specific actions of steroid hormone signaling in the central nervous system.