Background & Aims

Ectopic activity of peripheral nociceptors is thought to induce chronification of pain due to plastic changes in the central nervous system. However, concomitant changes in peripheral nociceptors remain largely enigmatic. We recently found that depolarization of nociceptors initiates an L-type calcium channel Cav1.2, calcium, and PKA signaling response resulting in acute peripheral hyperalgesia (Isensee et al., 2021). We have now explored whether Cav1.2-initiated signaling converts neuronal activity into transcriptional regulation known as excitation-transcription (E-T) coupling, thereby long lastingly altering animal pain behavior.

Methods

Dorsal root ganglion (DRG) neurons from rats and nociceptor-specific Cav1.2 knockout mice (Scn10aCre/+; Cacna1c-/-) were analyzed by High Content imaging (HCI), calcium imaging, and whole-cell patch clamp electrophysiology. The transcriptomes of DRGs from Cav1.2-deficient mice as well as DRG neurons after pharmacological activation/inhibition of Cav1.2 was determined by RNA-Seq. The behavior of Cav1.2-deficient mice was studied in models of acute nociceptive pain (hot plate, cold plate, von Frey) as well as in the Complete Freund‘s adjuvant model of inflammatory pain.

Results

HC imaging of cultured rat DRG neurons revealed that depolarization modulates the activity of the cAMP-response element binding protein (CREB), an important transcription regulator in long term plasticity (LTP), in a Cav1- and PKA-dependent manner. DRG neurons from nociceptor-specific Cav1.2 knockout mice showed reduced calcium influx, protein kinase A type II (PKA-II) activity, and CREB phosphorylation after mild depolarization. Also the repetitive generation of action potentials and the release of the neuropeptide CGRP were reduced in Cav1.2-deficient DRG neurons. Transcriptome analysis of DRGs from Cav1.2-deficient mice revealed downregulation of multiple calcium and potassium channel subunits as well as proteins involved in synaptic vesicle release and cell adhesion. In contrast, acute pharmacological modulation of Cav1 affected the expression of a small subset of depolarization-regulated genes that can orchestrate a broader transcriptional response. Notably, Cav1.2-deficient mice.

Conclusions

In summary, our data suggest a Cav1.2-dependent E-T coupling mechanism in nociceptors, which regulates the homeostatic expression level of multiple pain-related genes and pain behavior.

References

Isensee, J., M. van Cann, P. Despang, D. Araldi, K. Moeller, J. Petersen, A. Schmidtko, J. Matthes, J.D. Levine, and T. Hucho. 2021. Depolarization induces nociceptor sensitization by CaV1.2-mediated PKA-II activation. The Journal of cell biology. 220.

Presenting Author

Joerg Isensee

Poster Authors

Joerg Isensee

Dr. rer. nat.

University of Cologne

Lead Author

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Maximilian Loechte

University of Cologne

Lead Author

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Patrick Engel

Goethe University Frankfurt

Lead Author

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Ruirui Lu

Goethe University Frankfurt

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Maike Siobal

University of Cologne

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Mirjam Eberhardt

Hannover Medical School

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Inês Stein

Medizinische Hochschule Hannover

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Andreas Leffler

Hannover Medical School

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Achim Schmidtko

Goethe University Frankfurt

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Tim Hucho

University Hospital Cologne

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Topics

  • Mechanisms: Biological-Molecular and Cell Biology