Protein Kinase C Isoforms Differentially Phosphorylate Human Choline Acetyltransferase Regulating Its Catalytic Activity

Dobránsky, Tomàš; Doherty-Kirby, Amanda; Kim, Ae-Ri; Brewer, Dyanne; Lajoie, Gilles

doi:10.1074/jbc.m407085200

Cited by 28 publications

(32 citation statements)

References 49 publications

(53 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…We showed previously that phosphorylation of ChAT by protein kinase C or calcium/calmodulin‐dependent protein kinase II alters ChAT enzyme activity, indicating that ChAT function is influenced by dynamic phosphorylation (Dobransky et al . , , , ). Phosphorylation by tyrosine kinases can regulate protein stability of multiples members of the extracellular signal‐regulated kinase signaling pathway through the ubiquitin–proteasome system (Nguyen et al .…”

Section: Discussionmentioning

confidence: 99%

Enhanced ubiquitination and proteasomal degradation of catalytically deficient human choline acetyltransferase mutants

Morey

Albers

Shilton

et al. 2016

Journal of Neurochemistry

View full text Add to dashboard Cite

Choline acetyltransferase (ChAT) is essential for cholinergic neuron function as it mediates synthesis of the neurotransmitter acetylcholine. ChAT mutations have been linked to the neuromuscular disorder congenital myasthenic syndrome (CMS). One CMS-related ChAT mutation, V18M, reduces enzyme activity and cellular protein levels, and is positioned within a highly conserved proline-rich motif with the sequence 14 PKLPVPP 20 . We demonstrate that N-terminal truncation that includes this proline-rich motif, as well as mutation of prolines-17/19 together to alanine (P17A/P19A), dramatically reduces ChAT steady-state protein levels and cellular activity when expressed in cholinergic SN56 neural cells. The in vitro activity of bacterially expressed recombinant P17A/P19A-ChAT is also reduced, although this is not caused by changes in protein secondary structure or thermal stability. Treatment of SN56 cells with the proteasome inhibitor MG132 increases cellular P17A/P19A-ChAT steady-state protein levels, and by immunoprecipitation we found that ChAT is ubiquitinated and that polyubiquitination of P17A/P19A-ChAT is increased compared to wild-type (WT) ChAT. Using a novel fluorescentbiorthogonal pulse-chase protocol in SN56 cells, we determined that the protein half-life of P17A/P19A-ChAT (2.2 h) is substantially reduced compared to WT-ChAT (19.7 h). Lastly, we show that two CMS-related ChAT mutants (V18M and A513T) have enhanced ubiquitination, and that treatment with MG132 can partially restore both the steady-state protein levels as well as cellular activity of some CMS-mutant ChAT. These results identify a novel mechanism for regulation of ChAT through the ubiquitin-proteasome system that is influenced by the conserved N-terminal proline-rich motif of ChAT and may be implicated in CMS pathology.

show abstract

Section: Discussionmentioning

confidence: 99%

Enhanced ubiquitination and proteasomal degradation of catalytically deficient human choline acetyltransferase mutants

Morey

Albers

Shilton

et al. 2016

Journal of Neurochemistry

View full text Add to dashboard Cite

show abstract

“…The short‐term exposure to C3d induces high levels of ChAT activity and may indicate a novel mechanism of action. It has previously been shown that the ChAT protein can be phosphorylated and that phosphorylation may serve as an important regulator of its catalytic activity (Dobransky and Rylett, 2003, 2005; Dobransky et al, 2004). Furthermore, putative MAPK binding sites have been identified on the ChAT protein, making it possible that the activation of MAPK by NCAM, as shown in Figure 4, is acting to phosphorylate the ChAT protein and thereby increase ChAT activity.…”

Section: Discussionmentioning

confidence: 99%

Stimulation of choline acetyltransferase by C3d, a neural cell adhesion molecule ligand

Burgess

Saini

Weng

et al. 2008

J of Neuroscience Research

View full text Add to dashboard Cite

Septal cholinergic neurons project to the hippocampus and release acetylcholine, a neurotransmitter involved in learning and memory. The enzyme choline acetyltransferase (ChAT) is responsible for synthesizing acetylcholine. Promoting ChAT activity and acetylcholine release can lead to new treatments for neurodegenerative diseases with cholinergic deficits, such as Alzheimer's disease. We present evidence that the synthetic molecule C3d, which is a peptide mimetic of the neural cell adhesion molecule (NCAM), promotes ChAT activity in cultures of rat embryonic septal neurons. Our data demonstrate that ChAT activity triggered by C3d is dependent on the fibroblast growth factor receptor (FGFR) and the mitogen-activated protein kinase (MAPK) pathway. C3d did not affect the number of cholinergic neurons in culture, indicating that NCAM homophilic binding enhances ChAT activity, without affecting cholinergic cell survival. In conclusion, the NCAM mimetic peptide C3d promotes ChAT activity in septal neurons through FGFR and MAPK. These findings are relevant to the design of new strategies aimed at stimulating cholinergic function and improving cognition in disorders such as Alzheimer's disease.

show abstract

“…Choline acetyltransfase phosphorylation in neurons is mediated predominantly by PKC at Ser-476 (required for phosphorylation by PKC at other serine residues to proceed), with PKC activation increasing phosphorylation at Ser-440 and enhancing choline acetyltransferase activity [54].…”

Section: Cholinergic Systemmentioning

confidence: 99%

Protein Kinase C Pharmacology: Perspectives on Therapeutic Potentials as Antidementic and Cognitive Agents

Sun

Alkon²

2006

RPCN

View full text Add to dashboard Cite

Activity of protein kinase C (PKC) isozymes plays a critical role in various types of learning and memory. In addition, abnormal functions of PKC signal cascades in neurons represent one of the earliest changes in the brains of patients with Alzheimer's disease (AD) and dementia related to ischemic/stroke events. In preclinical studies, inhibition or impairment of PKC activity leads to compromised learning and memory, whereas an appropriate activation of PKC isozymes has been found to enhance learning and memory and/or to produce antidementic effects. The PKC activators not only increase activity of PKC isozymes and thereby restore PKC signaling activity but also reduce the accumulation of neurotoxic amyloid and tau protein hyperphosphorylation in the brain. These observations strongly suggest that PKC pharmacology may represent an attractive area for the development of cognitive therapeutics and agents against dementia in the future.

show abstract

Protein Kinase C Isoforms Differentially Phosphorylate Human Choline Acetyltransferase Regulating Its Catalytic Activity

Cited by 28 publications

References 49 publications

Enhanced ubiquitination and proteasomal degradation of catalytically deficient human choline acetyltransferase mutants

Enhanced ubiquitination and proteasomal degradation of catalytically deficient human choline acetyltransferase mutants

Stimulation of choline acetyltransferase by C3d, a neural cell adhesion molecule ligand

Protein Kinase C Pharmacology: Perspectives on Therapeutic Potentials as Antidementic and Cognitive Agents

Contact Info

Product

Resources

About