A‐kinase anchoring protein 150 expression in a specific subset of TRPV1‐ and Ca_V1.2‐positive nociceptive rat dorsal root ganglion neurons

Abstract

Modulation of phosphorylation states of ion channels is a critical step in the development of hyperalgesia during inflammation. Modulatory enhancement of channel activity may increase neuronal excitability and affect downstream targets such as gene transcription. The specificity required for such regulation of ion channels quickly occurs via targeting of protein kinases and phosphatases by the scaffolding A-kinase anchoring protein 79/150 (AKAP79/150). AKAP79/150 has been implicated in inflammatory pain by targeting PKA and PKC to the TRPV1 channel in peripheral sensory neurons, thus lowering threshold for activation by multiple inflammatory reagents. However, the expression pattern of AKAP79/150 in peripheral sensory neurons is unknown. In this study we use immunofluorescence microscopy to identify in DRG sections the peripheral neuron subtypes that express the rodent isoform AKAP150, as well as the subcellular distribution of AKAP150 and its potential target ion channels. We found that AKAP150 is predominantly expressed in a subset of small DRG sensory neurons where it is localized at the plasma membrane of the soma, axon initial segment and small fibers. The majority of these neurons is peripherin positive and produces c-fibers, though a small portion produces Aδ-fibers. Furthermore, we demonstrate that AKAP79/150 colocalizes with TRPV1 and CaV1.2 in the soma and axon initial segment. Thus AKAP150 is expressed in small, nociceptive DRG neurons where it is targeted to membrane regions and where it may play a role in the modulation of ion channel phosphorylation states required for hyperalgesia.

Clustering and Functional Coupling of Diverse Ion Channels and Signaling Proteins Revealed by Super-resolution STORM Microscopy in Neurons

“…In sensory neurons, TRPV1 cation channels excite neurons in response to heat, acidity or chemical ligands, initiating nociception (Caterina et al, 1997; Zheng, 2013). AKAP79/150 (human/rodent) recruits PKA, PKC, calcineurin (CaN), receptors and possibly transcription factors to organize signaling complexes centered on these three types of channels (Brandao et al, 2012; Chaudhury et al, 2011; Gomez et al, 2002; Hoshi et al, 2005; Kosenko et al, 2012; Tunquist et al, 2008). However, optical observation of individual AKAP79/150 protein complexes (<100 nm) with these proteins has not been achieved due to the intrinsic diffraction limit of light (~250 nm).…”

Trpv1

“…It therefore has an important role in the regulation of TRPV1 phosphorylation, and functionally the interaction between TRPV1 and AKAP79/150 is required for TRPV1 sensitisation or recovery from desensitisation. AKAP79/150 is expressed in 70-90 % of TRPV1-positive DRG neuron (Schnizler et al 2008;Zhang et al 2008;Brandao et al 2012), and co-precipitation studies have demonstrated a direct interaction between AKAP79/ 150 and TRPV1 (Schnizler et al 2008;Zhang et al 2008). …”

Disrupting Sensitization of Transient Receptor Potential Vanilloid Subtype 1 Inhibits Inflammatory Hyperalgesia

“…AKAP79 has been shown to interact with several other receptors and channels, such as the ␤2-adrenergic receptor, KCNQ2 channels, AMPA and NMDA receptors, and L-type voltage-gated Ca 2ϩ channels (for review, see Beene and Scott, 2007). The interaction of AKAP79 with AMPA and NMDA glutamate receptors has become an important topic of investigation in synaptic plasticity involved in memory and learning.…”

“…AKAP79 has also been shown to mediate the basal phosphorylation and dephosphorylation of AMPA GluR1 receptors in a process thought to underlie long-term depression (Tavalin et al, 2002). Moreover, activation of NMDA receptors can regulate the synaptic localization of AKAP79 through activation of calmodulin and remodeling of F-actin (Gomez et al, 2002) and can regulate AMPA receptor endocytosis through the interaction of AKAP79 and the postsynaptic density protein 95 (Bhattacharyya et al, 2009). More recently, it has been shown that NMDA receptor activation in trigeminal sensory neurons modulates AKAP150/ 79-mediated phosphorylation of TRPV1 by PKA and PKC (Lee et al, 2012), suggesting that TRPV1, NMDA receptor, and AKAP150/79 form a signaling complex that could be involved in the underlying sensitization of sensory neurons in inflammatory and neuropathic pain.…”