CRMP2 Is Involved in Regulation of Mitochondrial Morphology and Motility in Neurons.

Tatiana Brustovetsky,Nickolay Brustovetsky,Rajesh Khanna

doi:10.3390/cells10102781

Abstract

Regulation of mitochondrial morphology and motility is critical for neurons, but the exact mechanisms are unclear. Here, we demonstrate that these mechanisms may involve collapsin response mediator protein 2 (CRMP2). CRMP2 is attached to neuronal mitochondria and binds to dynamin-related protein 1 (Drp1), Miro 2, and Kinesin 1 light chain (KLC1). Treating neurons with okadaic acid (OA), an inhibitor of phosphatases PP1 and PP2A, resulted in increased CRMP2 phosphorylation at Thr509/514, Ser522, and Thr555, and augmented Drp1 phosphorylation at Ser616. The CRMP2-binding small molecule (S)-lacosamide ((S)-LCM) prevented an OA-induced increase in CRMP2 phosphorylation at Thr509/514 and Ser522 but not at Thr555, and also failed to alleviate Drp1 phosphorylation. The increased CRMP2 phosphorylation correlated with decreased CRMP2 binding to Drp1, Miro 2, and KLC1. (S)-LCM rescued CRMP2 binding to Drp1 and Miro 2 but not to KLC1. In parallel with CRMP2 hyperphosphorylation, OA increased mitochondrial fission and suppressed mitochondrial traffic. (S)-LCM prevented OA-induced alterations in mitochondrial morphology and motility. Deletion of CRMP2 with a small interfering RNA (siRNA) resulted in increased mitochondrial fission and diminished mitochondrial traffic. Overall, our data suggest that the CRMP2 expression level and phosphorylation state are involved in regulating mitochondrial morphology and motility in neurons.

Highlights

Adaptive changes in mitochondrial morphology and motility play a crucial role in neuronal responses to fluctuating energy demands in neuronal somata and at nerve terminals [1]
We found that mitochondria co-localize with collapsin response mediator protein 2 (CRMP2) in mouse cultured striatal neurons (Figure 1A–C) with Pearson’s correlation coefficient r = 0.547 ± 0.042
This suggested that CRMP2 may interact with mitochondria in neurons

Summary

Introduction

Adaptive changes in mitochondrial morphology and motility (mitochondrial dynamics) play a crucial role in neuronal responses to fluctuating energy demands in neuronal somata and at nerve terminals [1]. Impairments of mitochondrial dynamics contribute to different neuropathologies, such as Alzheimer’s, Parkinson’s, and Huntington’s diseases [1,2,3]. The exact molecular mechanisms involved in regulating mitochondrial dynamics are not completely understood. Collapsin response mediator proteins (CRMPs) represent a family of cytosolic proteins (CRMP1–5) that are expressed at high levels in the developing brain [4]. In contrast to other members of the CRMP family, CRMP2 retains a high level of expression in adults [8]. CRMP2 does not have enzymatic activity and its regulatory actions are mediated by its physical interaction with different proteins [7,9,10], including Kinesin 1 light chain (KLC1) and Dynein, motor proteins involved in axonal transport [11,12]

Methods

Results

Conclusion