KLHL1 Controls CaV3.2 Expression in DRG Neurons and Mechanical Sensitivity to Pain.

Elizabeth Martínez-Hernández,Paula Perissinotti,Jody L Martin,Alissa Zeglin,Yungui He,Michael Koob,Erika S Piedras-Rentería,Erik Almazan

doi:10.3389/fnmol.2019.00315

Elizabeth Martínez-Hernández, Paula Perissinotti + Show 6 more

Open Access

https://doi.org/10.3389/fnmol.2019.00315

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Abstract

Dorsal root ganglion (DRG) neurons process pain signaling through specialized nociceptors located in their peripheral endings. It has long been established low voltage-activated (LVA) CaV3.2 calcium channels control neuronal excitability during sensory perception in these neurons. Silencing CaV3.2 activity with antisense RNA or genetic ablation results in anti-nociceptive, anti-hyperalgesic and anti-allodynic effects. CaV3.2 channels are regulated by many proteins (Weiss and Zamponi, 2017), including KLHL1, a neuronal actin-binding protein that stabilizes channel activity by recycling it back to the plasma membrane through the recycling endosome. We explored whether manipulation of KLHL1 levels and thereby function as a CaV3.2 modifier can modulate DRG excitability and mechanical pain transmission or sensitivity to pain. We first assessed the mechanical sensitivity threshold and DRG properties in the KLHL1 KO mouse model. KO DRG neurons exhibited smaller T-type current density compared to WT without significant changes in voltage dependence, as expected in the absence of its modulator. Western blot analysis confirmed CaV3.2 but not CaV3.1, CaV3.3, CaV2.1, or CaV2.2 protein levels were significantly decreased; and reduced neuron excitability and decreased pain sensitivity were also found in the KLHL1 KO model. Analogously, transient down-regulation of KLHL1 levels in WT mice with viral delivery of anti-KLHL1 shRNA also resulted in decreased pain sensitivity. These two experimental approaches confirm KLHL1 as a physiological modulator of excitability and pain sensitivity, providing a novel target to control peripheral pain.

Highlights

Nociceptive pathways are generally activated in response to noxious stimuli as protection from injury, yet chronic pain induces allodynia and hyperalgesia due to primary dysfunction, usually caused by nerve injury
These data confirm the presence of Kelch-like 1 (KLHL1) in Dorsal root ganglion (DRG) neurons and its interaction with CaV3.2 T-type channels
Increased CaV3.2 function is found in chemotherapyinduced toxic neuropathies, and their inhibition with T-type calcium channels blockers decreases pain sensitivity (Flatters and Bennett, 2004; Okubo et al, 2011; Li et al, 2017)

Summary

Introduction

Nociceptive pathways are generally activated in response to noxious stimuli as protection from injury, yet chronic pain induces allodynia and hyperalgesia due to primary dysfunction, usually caused by nerve injury. The role of low voltage-activated (LVA) calcium CaV3.2 channels in pain sensation is well established; they contribute to nociception by lowering the threshold for action potential (AP). Treatment with T-type channel blockers results in reduced mechanical hyperalgesia in the spinal nerve ligation model (Dogrul et al, 2003; Chen et al, 2015). Manipulation of the expression levels of CaV3.2, as in the KO mouse model (Choi et al, 2007) or by selective knockdown in DRG neurons using antisense (Bourinet et al, 2005) results in attenuated pain responses, confirming the critical role of CaV3.2 in pain transmission

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