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Regulation of RGS mRNAs by cAMP in PC12 cells
D J Pepperl1, S Shah-Basu, D VanLeeuwen
1Parke-Davis Pharmaceutical Research, Ann Arbor, Michigan 48105, USA. pepperd@aa.wl.com
Abstract:
The RGS (regulators of G protein signaling) proteins represent a novel family of proteins which attenuate G protein mediated signaling. Using antisense riboprobes selective for rat RGS4, RGS7, and RGS2, we examined the regulation of these RGS mRNAs in PC12 cells in response to agents which elevate intracellular cAMP. Treatment of the PC12 cells with forskolin, dibutryl cAMP, or 8-CPT-cAMP for three hours decreased RGS4 message by nearly 50%. Actinomycin D, a potent inhibitor of transcription, did not affect the forskolin-induced decrease in RGS4 message, suggesting that forskolin does not alter RGS4 message half-life. RGS7 message is also present in these cells, but was not affected by forskolin. In contrast, RGS2 message is not evident in unstimulated cells but is strongly induced by one hour of treatment with forskolin. Taken together, these data suggest that mRNA levels of different RGS2 family members respond in an idiosynchratic fashion to cAMP challenge.
Insights
Regulators of G protein signaling (RGS) mRNA levels in PC12 cells show varied responses to elevated cAMP. RGS4 mRNA decreased, RGS7 mRNA remained unchanged, and RGS2 mRNA increased following cAMP stimulation.
Area of Science:
- Molecular Biology
- Cell Signaling
- Neuroscience
Background:
- Regulators of G protein signaling (RGS) proteins modulate G protein-mediated signal transduction.
- Understanding the regulation of RGS gene expression is crucial for deciphering cellular signaling pathways.
Purpose of the Study:
- To investigate the regulation of RGS4, RGS7, and RGS2 messenger RNA (mRNA) levels in PC12 cells.
- To determine how intracellular cyclic adenosine monophosphate (cAMP) levels influence the expression of different RGS family members.
Main Methods:
- PC12 cells were treated with agents that elevate intracellular cAMP, such as forskolin and cAMP analogs.
- Antisense riboprobes specific for rat RGS4, RGS7, and RGS2 were used to quantify mRNA levels.
- Actinomycin D was employed to assess the impact on mRNA half-life.
Main Results:
- Forskolin treatment significantly decreased RGS4 mRNA levels by approximately 50%.
- RGS7 mRNA levels were unaffected by forskolin treatment.
- RGS2 mRNA, undetectable in unstimulated cells, was markedly induced within one hour of forskolin treatment.
- Forskolin did not alter the half-life of RGS4 mRNA, as indicated by actinomycin D experiments.
Conclusions:
- Different members of the RGS2 family exhibit distinct and idiosyncratic responses in their mRNA levels to cAMP-mediated signaling challenges.
- These findings highlight the complex and differential regulation of RGS gene expression in response to cellular stimuli.