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Title: Ca{sup 2+}/calmodulin-dependent protein kinase phosphatase (CaMKP/PPM1F) interacts with neurofilament L and inhibits its filament association

Abstract

Ca{sup 2+}/calmodulin-dependent protein kinase phosphatase (CaMKP/PPM1F) is a Ser/Thr phosphatase that belongs to the PPM family. Growing evidence suggests that PPM phosphatases including CaMKP act as a complex with other proteins to regulate cellular functions. In this study, using the two-dimensional far-western blotting technique with digoxigenin-labeled CaMKP as a probe, in conjunction with peptide mass fingerprinting analysis, we identified neurofilament L (NFL) as a CaMKP-binding protein in a Triton-insoluble fraction of rat brain. We confirmed binding of fluorescein-labeled CaMKP (F-CaMKP) to NFL in solution by fluorescence polarization. The analysis showed that the dissociation constant of F-CaMKP for NFL is 73 ± 17 nM (n = 3). Co-immunoprecipitation assay using a cytosolic fraction of NGF-differentiated PC12 cells showed that endogenous CaMKP and NFL form a complex in cells. Furthermore, the effect of CaMKP on self-assembly of NFL was examined. Electron microscopy revealed that CaMKP markedly prevented NFL from forming large filamentous aggregates, suggesting that CaMKP-binding to NFL inhibits its filament association. These findings may provide new insights into a novel mechanism for regulating network formation of neurofilaments during neuronal differentiation. - Highlights: • NFL was identified as a CaMKP-binding protein in an insoluble fraction of rat brain. • CaMKP bound to NFL in solution with a K{submore » d} value of 73 ± 17 nM. • A CaMKP-NFL complex was found in NGF-differentiated PC12 cells. • CaMKP-binding to NFL inhibited its filament association. • CaMKP may regulate network formation of neurofilaments in neurons.« less

Authors:
 [1];  [2]; ;  [1]; ;  [3];  [2]; ;  [1];  [1]
  1. Laboratory of Molecular Brain Science, Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima, 739-8521 (Japan)
  2. Department of Biochemistry, Asahikawa Medical University, Asahikawa, 078-8510 (Japan)
  3. Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa, 761-0795 (Japan)
Publication Date:
OSTI Identifier:
22606188
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biochemical and Biophysical Research Communications; Journal Volume: 477; Journal Issue: 4; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; ALBUMINS; BRAIN; CALCIUM IONS; CALMODULIN; CATTLE; ELECTRON MICROSCOPY; FILAMENTS; FLUORESCEIN; FLUORESCENCE; FLUORIDES; GROWTH FACTORS; MASS SPECTROSCOPY; NERVE CELLS; PEPTIDES; PHOSPHATASES; PHOSPHATES; RATS; TRITONS; TRITURUS

Citation Formats

Ozaki, Hana, Katoh, Tsuyoshi, Nakagawa, Ryoko, Ishihara, Yasuhiro, Sueyoshi, Noriyuki, Kameshita, Isamu, Taniguchi, Takanobu, Hirano, Tetsuo, Yamazaki, Takeshi, and Ishida, Atsuhiko, E-mail: aishida@hiroshima-u.ac.jp. Ca{sup 2+}/calmodulin-dependent protein kinase phosphatase (CaMKP/PPM1F) interacts with neurofilament L and inhibits its filament association. United States: N. p., 2016. Web. doi:10.1016/J.BBRC.2016.06.141.
Ozaki, Hana, Katoh, Tsuyoshi, Nakagawa, Ryoko, Ishihara, Yasuhiro, Sueyoshi, Noriyuki, Kameshita, Isamu, Taniguchi, Takanobu, Hirano, Tetsuo, Yamazaki, Takeshi, & Ishida, Atsuhiko, E-mail: aishida@hiroshima-u.ac.jp. Ca{sup 2+}/calmodulin-dependent protein kinase phosphatase (CaMKP/PPM1F) interacts with neurofilament L and inhibits its filament association. United States. doi:10.1016/J.BBRC.2016.06.141.
Ozaki, Hana, Katoh, Tsuyoshi, Nakagawa, Ryoko, Ishihara, Yasuhiro, Sueyoshi, Noriyuki, Kameshita, Isamu, Taniguchi, Takanobu, Hirano, Tetsuo, Yamazaki, Takeshi, and Ishida, Atsuhiko, E-mail: aishida@hiroshima-u.ac.jp. 2016. "Ca{sup 2+}/calmodulin-dependent protein kinase phosphatase (CaMKP/PPM1F) interacts with neurofilament L and inhibits its filament association". United States. doi:10.1016/J.BBRC.2016.06.141.
@article{osti_22606188,
title = {Ca{sup 2+}/calmodulin-dependent protein kinase phosphatase (CaMKP/PPM1F) interacts with neurofilament L and inhibits its filament association},
author = {Ozaki, Hana and Katoh, Tsuyoshi and Nakagawa, Ryoko and Ishihara, Yasuhiro and Sueyoshi, Noriyuki and Kameshita, Isamu and Taniguchi, Takanobu and Hirano, Tetsuo and Yamazaki, Takeshi and Ishida, Atsuhiko, E-mail: aishida@hiroshima-u.ac.jp},
abstractNote = {Ca{sup 2+}/calmodulin-dependent protein kinase phosphatase (CaMKP/PPM1F) is a Ser/Thr phosphatase that belongs to the PPM family. Growing evidence suggests that PPM phosphatases including CaMKP act as a complex with other proteins to regulate cellular functions. In this study, using the two-dimensional far-western blotting technique with digoxigenin-labeled CaMKP as a probe, in conjunction with peptide mass fingerprinting analysis, we identified neurofilament L (NFL) as a CaMKP-binding protein in a Triton-insoluble fraction of rat brain. We confirmed binding of fluorescein-labeled CaMKP (F-CaMKP) to NFL in solution by fluorescence polarization. The analysis showed that the dissociation constant of F-CaMKP for NFL is 73 ± 17 nM (n = 3). Co-immunoprecipitation assay using a cytosolic fraction of NGF-differentiated PC12 cells showed that endogenous CaMKP and NFL form a complex in cells. Furthermore, the effect of CaMKP on self-assembly of NFL was examined. Electron microscopy revealed that CaMKP markedly prevented NFL from forming large filamentous aggregates, suggesting that CaMKP-binding to NFL inhibits its filament association. These findings may provide new insights into a novel mechanism for regulating network formation of neurofilaments during neuronal differentiation. - Highlights: • NFL was identified as a CaMKP-binding protein in an insoluble fraction of rat brain. • CaMKP bound to NFL in solution with a K{sub d} value of 73 ± 17 nM. • A CaMKP-NFL complex was found in NGF-differentiated PC12 cells. • CaMKP-binding to NFL inhibited its filament association. • CaMKP may regulate network formation of neurofilaments in neurons.},
doi = {10.1016/J.BBRC.2016.06.141},
journal = {Biochemical and Biophysical Research Communications},
number = 4,
volume = 477,
place = {United States},
year = 2016,
month = 9
}
  • Highlights: Black-Right-Pointing-Pointer CaMKP-N/PPM1E underwent proteolytic processing and translocated to cytosol. Black-Right-Pointing-Pointer The proteolysis was effectively inhibited by the proteasome inhibitors. Black-Right-Pointing-Pointer Ser-480 of zebrafish CaMKP-N was phosphorylated by cytosolic CaMKI. Black-Right-Pointing-Pointer Phosphorylation-mimic mutants of CaMKP-N showed enhanced activity. Black-Right-Pointing-Pointer These results suggest that CaMKP-N is regulated by CaMKI. -- Abstract: Nuclear Ca{sup 2+}/calmodulin-dependent protein kinase phosphatase (CaMKP-N/PPM1E) is an enzyme that dephosphorylates and downregulates multifunctional Ca{sup 2+}/calmodulin-dependent protein kinases (CaMKs) as well as AMP-dependent protein kinase. In our previous study, we found that zebrafish CaMKP-N (zCaMKP-N) underwent proteolytic processing and translocated to cytosol in a proteasome inhibitor-sensitive manner. In themore » present study, we found that zCaMKP-N is regulated by phosphorylation at Ser-480. When zCaMKP-N was incubated with the activated CaMKI, time-dependent phosphorylation of the enzyme was observed. This phosphorylation was significantly reduced when Ser-480 was replaced by Ala, suggesting that CaMKI phosphorylates Ser-480 of zCaMKP-N. Phosphorylation-mimic mutants, S480D and S480E, showed higher phosphatase activities than those of wild type and S480A mutant in solution-based phosphatase assay using various substrates. Furthermore, autophosphorylation of CaMKII after ionomycin treatment was more severely attenuated in Neuro2a cells when CaMKII was cotransfected with the phosphorylation-mimic mutant of zCaMKP-N than with the wild-type or non-phosphorylatable zCaMKP-N. These results strongly suggest that phosphorylation of zCaMKP-N at Ser-480 by CaMKI activates CaMKP-N catalytic activity and thereby downregulates multifunctional CaMKs in the cytosol.« less
  • Ca{sup 2+}/calmodulin-dependent protein kinase phosphatase (CaMKP) and its nuclear isoform CaMKP-N are unique Ser/Thr protein phosphatases that negatively regulate the Ca{sup 2+}/calmodulin-dependent protein kinase (CaMK) cascade by dephosphorylating multifunctional CaMKI, II, and IV. However, the lack of specific inhibitors of these phosphatases has hampered studies on these enzymes in vivo. In an attempt to obtain specific inhibitors, we searched inhibitory compounds and found that Evans Blue and Chicago Sky Blue 6B served as effective inhibitors for CaMKP. These compounds also inhibited CaMKP-N, but inhibited neither protein phosphatase 2C, another member of PPM family phosphatase, nor calcineurin, a typical PPP familymore » phosphatase. The minimum structure required for the inhibition was 1-amino-8-naphthol-4-sulfonic acid. When Neuro2a cells cotransfected with CaMKIV and CaMKP-N were treated with these compounds, the dephosphorylation of CaMKIV was strongly suppressed, suggesting that these compounds could be used as potent inhibitors of CaMKP and CaMKP-N in vivo as well as in vitro.« less
  • Calcium-dependent mechanisms, particularly those mediated by Ca{sup 2+}/calmodulin (CaM)-dependent protein kinase II (CaMKII), have been implicated in neurotoxicant-induced neuropathy. However, it is unknown whether similar mechanisms exist in 2,5-hexanedione (HD)-induced neuropathy. For that, we investigated the changes of CaM, CaMKII, protein kinase C (PKC) and polymerization ratios (PRs) of NF-L, NF-M and NF-H in cerebral cortex (CC, including total cortex and some gray), spinal cord (SC) and sciatic nerve (SN) of rats treated with HD at a dosage of 1.75 or 3.50 mmol/kg for 8 weeks (five times per week). The results showed that CaM contents in CC, SC andmore » SN were significantly increased, which indicated elevation of Ca{sup 2+} concentrations in nerve tissues. CaMKII contents and activities were also increased in CC and were positively correlated with gait abnormality, but it could not be found in SC and SN. The increases of PKC contents and activities were also observed in SN and were positively correlated with gait abnormality. Except for that of NF-M in CC, the PRs of NF-L, NF-M and NF-H were also elevated in nerve tissues, which was consistent with the activation of protein kinases. The results suggested that CaMKII might be partly (in CC but not in SC and SN) involved in HD-induced neuropathy. CaMKII and PKC might mediate the HD neurotoxicity by altering the NF phosphorylation status and PRs.« less
  • No abstract prepared.
  • The amino acid sequence of the Alzheimer disease amyloid precursor (ADAP) has been deduced from the corresponding cDNA, and hydropathy analysis of the sequence suggest a receptor-like structure with a single transmembrane domain. The putative cytoplasmic domain of ADAP contains potential sites for serine and threonine phosphorylation. In the present study, synthetic peptides derived from this domain were used as model substrates for various purified protein kinases. Protein kinase C rapidly catalyzed the phosphorylation of a peptide corresponding to amino acid residues 645-661 of ADAP. Ca{sup 2+}/calmodulin-dependent protein kinase II phosphorylated ADAP peptide (645-661) on Thr-654 and Ser-655. Using ratmore » cerebral cortex synaptosomes prelabeled with {sup 32}P{sub i}, a {sup 32}P-labeled phosphoprotein of {approx}135 kDa was immunoprecipitated by using antisera prepared against ADAP peptide(597-624), consistent with the possibility that the holoform of ADAP in rat brain is a phosphoprotein. Based on analogy with the effect of phosphorylation by protein kinase C of juxtamembrane residues in the cytoplasmic domain of the epidermal growth factor receptor and the interleukin 2 receptor, phosphorylation of ADAP may target it for internalization.« less