The acetylation of cyclin-dependent kinase 5 at lysine 33 regulates kinase activity and neurite length in hippocampal neurons

Juhyung Lee,Young J Oh,Yuhyun Chung,Kyungjin Kim,Nuri Yun,Myungjin Kim,Yeon Uk Ko

doi:10.1038/s41598-018-31785-9

Abstract

Cyclin-dependent kinase 5 (CDK5) plays a pivotal role in neural development and neurodegeneration. CDK5 activity can be regulated by posttranslational modifications, including phosphorylation and S-nitrosylation. In this study, we demonstrate a novel mechanism by which the acetylation of CDK5 at K33 (Ac-CDK5) results in the loss of ATP binding and impaired kinase activity. We identify GCN5 and SIRT1 as critical factor controlling Ac-CDK5 levels. Ac-CDK5 achieved its lowest levels in rat fetal brains but was dramatically increased during postnatal periods. Intriguingly, nuclear Ac-CDK5 levels negatively correlated with neurite length in embryonic hippocampal neurons. Either treatment with the SIRT1 activator SRT1720 or overexpression of SIRT1 leads to increases in neurite length, whereas SIRT1 inhibitor EX527 or ectopic expression of acetyl-mimetic (K33Q) CDK5 induced the opposite effect. Furthermore, the expression of nuclear-targeted CDK5 K33Q abolished the SRT1720-induced neurite outgrowth, showing that SIRT1 positively regulates neurite outgrowth via deacetylation of nuclear CDK5. The CDK5 activity-dependent increase of neurite length was mediated by enhanced transcriptional regulation of BDNF via unknown mechanism(s). Our findings identify a novel mechanism by which acetylation-mediated regulation of nuclear CDK5 activity plays a critical role in determining neurite length in embryonic neurons.

Highlights

Cyclin-dependent kinase 5 (CDK5), a proline-directed serine/threonine kinase, is closely related to other cyclin-dependent kinases and is expressed in various tissues, its highest level is found in the brain[1,2,3]
Human embryonic kidney 293 (HEK293) cells were transfected with CDK5 wild type (WT) or CDK5 mutants in which K33 was substituted with arginine (K33R; acetyl null) or glutamine (K33Q; acetyl mimetic) in combination with p35 or p25
In immunoprecipitation and immunoblot analyses, this antibody detected only a single band in the immunoprecipitates obtained from HEK293 cells transfected with GCN5 and CDK5 WT (Supplementary Fig. 2)

Summary

Introduction

Cyclin-dependent kinase 5 (CDK5), a proline-directed serine/threonine kinase, is closely related to other cyclin-dependent kinases and is expressed in various tissues, its highest level is found in the brain[1,2,3]. CDK5 expression and kinase activity closely correlate with the extent of neuronal differentiation[2,10,11]. Mutant CDK5 lacking these cysteine residues delays dendritic development in hippocampal neurons Another group reported an opposing outcome for the S-nitrosylation of CDK5 in Aβ1–42 and NMDA-induced dendritic spine loss[23]. While searching for additional posttranslational modifications of CDK5, we previously found that general control non-derepressible 5 (GCN5, KAT2A) acetylates CDK5 at K3325 Prompted by this observation, we investigated (i) whether CDK5 acetylation affects its kinase activity and (ii) whether it is involved in neuronal differentiation. We further demonstrated that (de)acetylated CDK5 levels and concomitant kinase activity were controlled by SIRT1 in developing hippocampal neurons. Our findings suggest a novel mechanism to regulate CDK5 activity in the nucleus and highlight the crucial role of CDK5 in determining neurite length in the developing brain

Methods

Results

Conclusion