Cyclic GMP-Gated CNG Channels Function in Sema3A-Induced Growth Cone Repulsion

Abstract

Cyclic nucleotide-gated channels (CNGCs) transduce external signals required for sensory processes, e.g., photoreception, olfaction, and taste. Nerve growth cone guidance by diffusible attractive and repulsive molecules is regulated by differential growth cone Ca2+ signaling. However, the Ca2+-conducting ion channels that transduce guidance molecule signals are largely unknown. We show that rod-type CNGC-like channels function in the repulsion of cultured Xenopus spinal neuron growth cones by Sema3A, which triggers the production of the cGMP that activates the Xenopus CNGA1 (xCNGA1) subunit-containing channels in interneurons. Downregulation of xCNGA1 or overexpression of a mutant xCNGA1 incapable of binding cGMP abolished CNG currents and converted growth cone repulsion to attraction in response to Sema3A. We also show that Ca2+ entry through xCNGCs is required to mediate the repulsive Sema3A signal. These studies extend our knowledge of the function of CNGCs by demonstrating their requirement for signal transduction in growth cone guidance.

Function of theDrosophilareceptor guanylyl cyclase Gyc76C in PlexA-mediated motor axon guidance

“…This is reminiscent of Sema-3A bath application increasing intracellular cGMP levels in Xenopus spinal neurons in vitro (Togashi et al, 2008), and our results suggest that intracellular cGMP produced by Gyc76C is required for Sema-1a-mediated repulsion. However, it is possible that signaling by intracellular cGMP is coupled with intracellular cAMP in Sema-1a-mediated repulsive guidance events (Nishiyama et al, 2003), and future work will determine whether varying the cAMP-to-cGMP ratio modulates Sema-1a-mediated repulsion, or converts it to attraction.…”

“…Elevated cAMP in cultured DRG neurons neutralizes Sema-3A growth cone collapse, whereas elevated cGMP potentiates it (Dontchev and Letourneau, 2002). The ratio of cAMP to cGMP can determine the sign of a growth cone steering response (Nishiyama et al, 2003), and Sema-3A induces cGMP production in neuronal growth cones, activating of cGMP-gated calcium channels (CNGCs), Ca 2+ influx and repulsion (Togashi et al, 2008). cAMP and cGMP regulate kinases and phosphodiesterases to direct formation of axons or dendrites in cultured hippocampal neurons (Shelly et al, 2010).…”

Regulation of dendritic development by semaphorin 3A through novel intracellular remote signaling

“…The signaling pathways of Sema3A involved in growth cone collapse and axonal transport may share some elements, including extracellular calcium ions. 55,56 Sema3A-induced growth cone collapse was inhibited by hanatoxin (a voltage-gated K C or Ca 2C channel blocker), 57 voltage-dependent L-type Ca 2C channel blockers such as nimodipine, and a reduction in extracellular Ca 2C . 54,56,[58][59][60] Sema3A enhances intracellular Ca 2C in the growth cones, 54,56,60,61 through which Sema3A can enhance both endocytosis and exocytosis.…”

“…55,56 Sema3A-induced growth cone collapse was inhibited by hanatoxin (a voltage-gated K C or Ca 2C channel blocker), 57 voltage-dependent L-type Ca 2C channel blockers such as nimodipine, and a reduction in extracellular Ca 2C . 54,56,[58][59][60] Sema3A enhances intracellular Ca 2C in the growth cones, 54,56,60,61 through which Sema3A can enhance both endocytosis and exocytosis. 60,62 Sema3A-induced growth cone collapse or repulsive turning was shown to be mediated through Ca 2C -triggered clathrin-mediated endocytosis.…”

Using microfluidic chip to form brain-derived neurotrophic factor concentration gradient for studying neuron axon guidance

“…Researches show that some of the most important cues guiding the formation of connections between neurons in the developing nervous system are molecular gradients (Masuda et al, 2012;Lowery and Van Vactor, 2009). When a growth cone migrates in a guidance cue gradient, the side of the growth cone facing higher concentrations of the cue will experience higher receptor occupancy (Tojima et al, 2011), leading to asymmetric intracellular signaling events mediated by second messengers such as Ca 2þ and cyclic nucleotides (Akiyama et al, 2009;Togashi et al, 2008). This leads to polarization of the growth cone and a turn toward or away from the source of the guidance cue (Forbes et al, 2012).…”