Protein synthesis inhibition promotes nitric oxide generation and activation of CGKII-dependent downstream signaling pathways in the retina

• Published in: Biochimica et biophysica acta. Molecular cell research 2020-08, Vol.1867 (8), p.118732-118732, Article 118732
• Main Authors: Cossenza, Marcelo, Socodato, Renato, Mejía-García, Telmo A., Domith, Ivan, Portugal, Camila C., Gladulich, Luis F.H., Duarte-Silva, Aline T., Khatri, Latika, Antoine, Shannon, Hofmann, Franz, Ziff, Edward B., Paes-de-Carvalho, Roberto
• Format: Article
• Language: English
• Subjects: AKT; Cyclic GMP-dependent kinase type II (cGKII); ERK MAP kinase; L-arginine; Protein synthesis inhibitor; Retina
• ISSN: 0167-4889; 1879-2596
• DOI: 10.1016/j.bbamcr.2020.118732

Nitric oxide is an important neuromodulator in the CNS, and its production within neurons is modulated by NMDA receptors and requires a fine-tuned availability of L-arginine. We have previously shown that globally inhibiting protein synthesis mobilizes intracellular L-arginine “pools” in retinal neurons, which concomitantly enhances neuronal nitric oxide synthase-mediated nitric oxide production. Activation of NMDA receptors also induces local inhibition of protein synthesis and L-arginine intracellular accumulation through calcium influx and stimulation of eucariotic elongation factor type 2 kinase. We hypothesized that protein synthesis inhibition might also increase intracellular L-arginine availability to induce nitric oxide-dependent activation of downstream signaling pathways. Here we show that nitric oxide produced by inhibiting protein synthesis (using cycloheximide or anisomycin) is readily coupled to AKT activation in a soluble guanylyl cyclase and cGKII-dependent manner. Knockdown of cGKII prevents cycloheximide or anisomycin-induced AKT activation and its nuclear accumulation. Moreover, in retinas from cGKII knockout mice, cycloheximide was unable to enhance AKT phosphorylation. Indeed, cycloheximide also produces an increase of ERK phosphorylation which is abrogated by a nitric oxide synthase inhibitor. In summary, we show that inhibition of protein synthesis is a previously unanticipated driving force for nitric oxide generation and activation of downstream signaling pathways including AKT and ERK in cultured retinal cells. These results may be important for the regulation of synaptic signaling and neuronal development by NMDA receptors as well as for solving conflicting data observed when using protein synthesis inhibitors for studying neuronal survival during development as well in behavior and memory studies. [Display omitted] •Protein synthesis is an unanticipated driving force for NO production in retina.•Protein synthesis inhibition increases L-arginine availability and NO production.•Protein synthesis inhibition stimulates canonical NO-dependent cGMP/cGK2 pathway.•Protein synthesis inhibition triggers downstream NO-dependent AKT and ERK activation.•Studies using protein synthesis inhibitors must be reevaluated due to NO production.