Dataset Information

MLC phosphorylation by the kinase CaMKII

ABSTRACT: MLC1 is membrane protein highly expressed by brain perivascular astrocytes. Mutations in MLC1 account for megalencephalic leukoencephalopathy with subcortical cysts (MLC), an incurable leu-kodystrophy characterized by macrocephaly, brain edema and cysts, myelin vacuolation and as-trocyte swelling, that cause cognitive and motor dysfunctions. MLC pathological models demon-strated that in astrocytes MLC1 mutations affect the swelling-activated Cl- currents (ICl,swell) medi-ated by volume-regulated anion channel (VRAC) and the consequent regulatory volume decrease (RVD), and also induce the abnormal activation of intracellular signaling pathways linked to in-flammation/osmotic stress. Despite this knowledge, MLC1 function and MLC molecular pathogen-esis are still elusive. Following the observations that calcium regulates all the MLC1-modulated processes and that intracellular Ca2+ homeostasis is altered in MLC1-defective cells, we applied biochemistry, molecular biology, video imaging, electrophysiology and proteomic techniques on cultured human and mouse astrocytes to study MLC1/calcium signaling relationships. We revealed that MLC1 binds the Ca2+ effector proteins calmodulin (CaM) and Ca2+/CaM-dependent protein ki-nase II (CaMKII) and, as result, changes its assembly, localization and functional properties in re-sponse to Ca2+ influx or release. Noteworthy, CaM binding to the COOH terminal promotes MLC1 trafficking to the plasma membrane, while CaMKII phosphorylation of the NH2 end potentiates MLC1 activation of ICl,swell, that are critically important for RVD. Overall, our results show that MLC1 is a Ca2+-regulated protein linking VRAC function and volume regulation to Ca2+ signaling in astro-cytes, opening new avenues to clarify the defective molecular pathways of MLC and other diseas-es where astrocyte swelling and brain edema underlie the pathological process. In this contest we submit here the MS data showing MLC phosphorylation on Threonine 17.

INSTRUMENT(S): LTQ

ORGANISM(S): Homo Sapiens (human)

SUBMITTER: Serena Camerini

LAB HEAD: Serena Camerini

PROVIDER: PXD030549 | Pride | 2022-10-13

REPOSITORIES: Pride

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Publications

The CaMKII/MLC1 Axis Confers Ca<sup>2+</sup>-Dependence to Volume-Regulated Anion Channels (VRAC) in Astrocytes.

Brignone Maria Stefania MS Lanciotti Angela A Michelucci Antonio A Mallozzi Cinzia C Camerini Serena S Catacuzzeno Luigi L Sforna Luigi L Caramia Martino M D'Adamo Maria Cristina MC Ceccarini Marina M Molinari Paola P Macioce Pompeo P Macchia Gianfranco G Petrucci Tamara Corinna TC Pessia Mauro M Visentin Sergio S Ambrosini Elena E

Cells 20220826 17

Astrocytes, the main glial cells of the central nervous system, play a key role in brain volume control due to their intimate contacts with cerebral blood vessels and the expression of a distinctive equipment of proteins involved in solute/water transport. Among these is MLC1, a protein highly expressed in perivascular astrocytes and whose mutations cause megalencephalic leukoencephalopathy with subcortical cysts (MLC), an incurable leukodystrophy characterized by macrocephaly, chronic brain ede ...[more]

PMID: 36078064

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Project description:This the full model from the article: A dynamic model of interactions of Ca2+, calmodulin, and catalytic subunits of Ca2+/calmodulin-dependent protein kinase II. Pepke S, Kinzer-Ursem T, Mihalas S, Kennedy MB. PLoS Comput Biol 2010 Feb 12;6(2):e1000675. PMID: 20168991 , doi: 10.1371/journal.pcbi.1000675 ; Abstract: During the acquisition of memories, influx of Ca2+ into the postsynaptic spine through the pores of activated N-methyl-D-aspartate-type glutamate receptors triggers processes that change the strength of excitatory synapses. The pattern of Ca2+influx during the first few seconds of activity is interpreted within the Ca2+-dependent signaling network such that synaptic strength is eventually either potentiated or depressed. Many of the critical signaling enzymes that control synaptic plasticity,including Ca2+/calmodulin-dependent protein kinase II (CaMKII), are regulated by calmodulin, a small protein that can bindup to 4 Ca2+ ions. As a first step toward clarifying how the Ca2+-signaling network decides between potentiation or depression, we have created a kinetic model of the interactions of Ca2+, calmodulin, and CaMKII that represents our best understanding of the dynamics of these interactions under conditions that resemble those in a postsynaptic spine. We constrained parameters of the model from data in the literature, or from our own measurements, and then predicted time courses of activation and autophosphorylation of CaMKII under a variety of conditions. Simulations showed that species of calmodulin with fewer than four bound Ca2+ play a significant role in activation of CaMKII in the physiological regime,supporting the notion that processing of Ca2+ signals in a spine involves competition among target enzymes for binding to unsaturated species of CaM in an environment in which the concentration of Ca2+ is fluctuating rapidly. Indeed, we showed that dependence of activation on the frequency of Ca2+ transients arises from the kinetics of interaction of fluctuating Ca2+with calmodulin/CaMKII complexes. We used parameter sensitivity analysis to identify which parameters will be most beneficial to measure more carefully to improve the accuracy of predictions. This model provides a quantitative base from which to build more complex dynamic models of postsynaptic signal transduction during learning. The nomenclature of the different Calmodulin forms in th emodel differs from the description in the article. The C and N terminal Ca 2+ binding sites are described by the numbers at each species name, with the first entry indicating the number of Ca 2+ ions bound to the C and the second the ones bound on the N terminal sites. In complexes with two CaM, the four numbers at the end indicate _C_N_C_N. For example: CaM1N2C in the article is CaM_2_1 in the model, CaM4 is CaM_2_2 and KCaMcomplex_0_1_1_2 stands for CaMKII bound to CaM1C and CaM2N1C . This is a Systems Biology Markup Language (SBML) file, originally generated by MathSBML 2.9.0 [8-Oct-2008] 15-Jan-2010 13:13:32 (GMT-07:60). SBML is a form of XML, and most XML files will not display properly in an internet browser. To view the contents of an XML file use the "Page Source" or equivalent button on you browser. This model originates from BioModels Database: A Database of Annotated Published Models (http://www.ebi.ac.uk/biomodels/). It is copyright (c) 2005-2011 The BioModels.net Team. To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information. In summary, you are entitled to use this encoded model in absolutely any manner you deem suitable, verbatim, or with modification, alone or embedded it in a larger context, redistribute it, commercially or not, in a restricted way or not.. To cite BioModels Database, please use: Li C, Donizelli M, Rodriguez N, Dharuri H, Endler L, Chelliah V, Li L, He E, Henry A, Stefan MI, Snoep JL, Hucka M, Le Novère N, Laibe C (2010) BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models. BMC Syst Biol., 4:92.

Dataset Information

MLC phosphorylation by the kinase CaMKII

Publications

The CaMKII/MLC1 Axis Confers Ca<sup>2+</sup>-Dependence to Volume-Regulated Anion Channels (VRAC) in Astrocytes.

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