Calcium-ion and calmodulin-dependent kappa-casein kinase in rat mammary acini.
Ontology highlight
ABSTRACT:
SUBMITTER: Brooks CL
PROVIDER: S-EPMC1144413 | biostudies-other | 1984 Nov
REPOSITORIES: biostudies-other
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Project description:Elevation of intracellular calcium was traditionally thought to be detrimental in stroke pathology. However, clinical trials testing treatments that block calcium signaling have failed to improve outcomes in ischemic stroke. Emerging data suggest that calcium may also trigger endogenous protective pathways after stroke. Calcium/calmodulin-dependent protein kinase kinase (CaMKK) is a major kinase activated by rising intracellular calcium. Compelling evidence has suggested that CaMKK and its downstream kinase CaMK IV are critical in neuronal survival when cells are under ischemic stress. We examined the functional role of CaMKK/CaMK IV signaling in stroke.We used a middle cerebral artery occlusion model in mice.Our data demonstrated that pharmacological and genetic inhibition of CaMKK aggravated stroke injury. Additionally, deletion of CaMKK ?, one of the 2 CaMKK isoforms, reduced CaMK IV activation, and CaMK IV deletion in mice worsened stroke outcome. Finally, CaMKK ? or CaMK IV knockout mice had exacerbated blood-brain barrier disruption evidenced by increased hemorrhagic transformation and activation of matrix metalloproteinase. We observed transcriptional inactivation including reduced levels of histone deacetylase 4 phosphorylation in mice with CaMKK ? or CaMK IV deletion after stroke.Our data have established that the CaMKK/CaMK IV pathway is a key endogenous protective mechanism in ischemia. Our results suggest that this pathway serves as an important regulator of blood-brain barrier integrity and transcriptional activation of neuroprotective molecules in stroke.
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Project description:Calcium/calmodulin-dependent protein kinase II (CaMKII) interprets information conveyed by the amplitude and frequency of calcium transients by a controlled transition from an autoinhibited basal intermediate to an autonomously active phosphorylated intermediate (De Koninck and Schulman, 1998). We used spin labelling and electron paramagnetic resonance spectroscopy to elucidate the structural and dynamic bases of autoinhibition and activation of the kinase domain of CaMKII. In contrast to existing models, we find that autoinhibition involves a conformeric equilibrium of the regulatory domain, modulating substrate and nucleotide access. Binding of calmodulin to the regulatory domain induces conformational changes that release the catalytic cleft, activating the kinase and exposing an otherwise inaccessible phosphorylation site, threonine 286. Autophosphorylation at Thr286 further disrupts the interactions between the catalytic and regulatory domains, enhancing the interaction with calmodulin, but maintains the regulatory domain in a dynamic unstructured conformation following dissociation of calmodulin, sustaining activation. These findings support a mechanistic model of the CaMKII holoenzyme grounded in a dynamic understanding of autoregulation that is consistent with a wealth of biochemical and functional data.
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Project description:The calcium calmodulin protein kinase II (CaMKII) is a multi-subunit ring assembly with a central hub formed by the association domains. There is evidence for hub polymorphism between and within CaMKII isoforms, but the link between polymorphism and subunit exchange has not been resolved. Here, we present near-atomic resolution cryogenic electron microscopy (cryo-EM) structures revealing that hubs from the α and β isoforms, either standalone or within an β holoenzyme, coexist as 12 and 14 subunit assemblies. Single-molecule fluorescence microscopy of Venus-tagged holoenzymes detects intermediate assemblies and progressive dimer loss due to intrinsic holoenzyme lability, and holoenzyme disassembly into dimers upon mutagenesis of a conserved inter-domain contact. Molecular dynamics (MD) simulations show the flexibility of 4-subunit precursors, extracted in-silico from the β hub polymorphs, encompassing the curvature of both polymorphs. The MD explains how an open hub structure also obtained from the β holoenzyme sample could be created by dimer loss and analysis of its cryo-EM dataset reveals how the gap could open further. An assembly model, considering dimer concentration dependence and strain differences between polymorphs, proposes a mechanism for intrinsic hub lability to fine-tune the stoichiometry of αβ heterooligomers for their dynamic localization within synapses in neurons.
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Project description:Hematopoietic stem and progenitor cells (HSPCs) are predominantly quiescent in adults, but proliferate in response to bone marrow (BM) injury. Here, we show that deletion of Ca2+/calmodulin (CaM)-dependent protein kinase kinase 2 (CaMKK2) promotes HSPC regeneration and hematopoietic recovery following radiation injury. Using Camkk2-enhanced green fluorescent protein (EGFP) reporter mice, we found that Camkk2 expression is developmentally regulated in HSPC. Deletion of Camkk2 in HSPC results in a significant downregulation of genes affiliated with the quiescent signature. Accordingly, HSPC from Camkk2 null mice have a high proliferative capability when stimulated in vitro in the presence of BM-derived endothelial cells. In addition, Camkk2 null mice are more resistant to radiation injury and show accelerated hematopoietic recovery, enhanced HSPC regeneration and ultimately a prolonged survival following sublethal or lethal total body irradiation. Mechanistically, we propose that CaMKK2 regulates the HSPC response to hematopoietic damage by coupling radiation signaling to activation of the anti-proliferative AMP-activated protein kinase. Finally, we demonstrated that systemic administration of the small molecule CaMKK2 inhibitor, STO-609, to irradiated mice enhanced HSPC recovery and improved survival. These findings identify CaMKK2 as an important regulator of HSPC regeneration and demonstrate CaMKK2 inhibition is a novel approach to promoting hematopoietic recovery after BM injury.
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Project description:Gastric cancer is one of the most common gastrointestinal malignancies and is associated with poor prognosis. Exploring alterations in the proteomic landscape of gastric cancer is likely to provide potential biomarkers for early detection and molecules for targeted therapeutic intervention. Using iTRAQ-based quantitative proteomic analysis, we identified 22 proteins that were overexpressed and 17 proteins that were downregulated in gastric tumor tissues as compared to the adjacent normal tissue. Calcium/calmodulin-dependent protein kinase kinase 2 (CAMKK2) was found to be 7-fold overexpressed in gastric tumor tissues. Immunohistochemical labeling of tumor tissue microarrays for validation of CAMKK2 overexpression revealed that it was indeed overexpressed in 94% (92 of 98) of gastric cancer cases. Silencing of CAMKK2 using siRNA significantly reduced cell proliferation, colony formation and invasion of gastric cancer cells. Our results demonstrate that CAMKK2 signals in gastric cancer through AMPK activation and suggest that CAMKK2 could be a novel therapeutic target in gastric cancer.
| S-EPMC4622549 | biostudies-literature
Project description:Kidney podocytes and their slit diaphragms contribute to prevent urinary protein loss. T cell from patients with systemic lupus erythematosus display increased expression of calcium/calmodulin kinase IV (CaMKIV). Here we evaluated the functional role of CaMKIV in lupus nephritis (LN) using kidney biopsy specimens and human podocyte cell line (AB8/13). We found that exposure of podocytes to IgG from LN patients resulted in entry of IgG into the cytoplasm. CaMKIV expression was found to be increased in podocytes of LN kidney biopsy specimens and exposure to IgG from LN patients. IgG entered podocytes using the FcRn receptor because when podocytes where treated with FcRn siRNA less IgG was found in the cytoplasm. The DNA microarray studies of podocytes exposed to LN IgG revealed that genes that are related to the activation of immune cells or podocyte damage were upregulated. These genes included CD86, CaMKIV, PTPN22, PDE5A, CD47 and MALT1. Interestingly, CD86 expression decreased after silencing CaMKIV in podocytes. Also, in situ hybridization experiments showed that the expression of CD86 was reduced in podocytes from MRL/lpr.camkivM-bM-^HM-^R/M-bM-^HM-^R mice. IgG from LN patients may enter podocytes through the FcRn and causes the upregulation of a distinct set of genes which may alter podocyte function. Upregulation of CaMKIV appears to precede that of genes known to be linked to podocyte damage such as CD86. These findings may indicate that inhibition of CaMKIV may prove of clinical use in patients with LN. IgG Purification Kits (Dojindo Molecular Technologies, Inc.) are used for isolation and purification of immunoglobulin G of healthy and normal individual according to the manufacturerM-bM-^@M-^Ys protocol. Flow through the column was used for non IgG binding samples. Cultured human podocytes with IgG purified from sera of normal individuals and LN patient for 24 hr were collected for RNA.
2014-08-01 | E-GEOD-55768 | biostudies-arrayexpress
Project description:Similar to phosphorylation, GlcNAcylation (the addition of O-GlcNAc to Ser(Thr) residues on polypeptides) is an abundant, dynamic, and inducible post-translational modification. GlcNAcylated proteins are crucial in regulating virtually all cellular processes, including signaling, cell cycle, and transcription. Here we show that calcium/calmodulin-dependent kinase IV (CaMKIV) is highly GlcNAcylated in vivo. In addition, we show that upon activation of HEK293 cells, hemagglutinin-tagged CaMKIV GlcNAcylation rapidly decreases, in a manner directly opposing its phosphorylation at Thr-200. Correspondingly, there is an increase in CaMKIV interaction with O-GlcNAcase during CaMKIV activation. Furthermore, we identify at least five sites of GlcNAcylation on CaMKIV. Using site-directed mutagenesis, we determine that the GlcNAcylation sites located in the active site of CaMKIV can modulate its phosphorylation at Thr-200 and its activity toward cAMP-response element-binding transcription factor. Our results strongly indicate that the O-GlcNAc modification participates in the regulation of CaMKIV activation and function, possibly coordinating nutritional signals with the immune and nervous systems. This is the first example of an O-GlcNAc/phosphate cycle involving O-GlcNAc transferase/kinase cross-talk.
| S-EPMC2755857 | biostudies-literature
Project description:The calcium calmodulin-dependent protein kinase II (CaMKII) is a dodecameric holoenzyme important for encoding memory. Its activation, triggered by binding of calcium-calmodulin, persists autonomously after calmodulin dissociation. One (receiver) kinase captures and subsequently phosphorylates the regulatory domain peptide of a donor kinase forming a chained dimer as the first stage of autonomous activation. Protein dynamics simulations examined the conformational changes triggered by dimer formation and phosphorylation, aimed to provide a molecular rationale for human mutations that result in learning disabilities. Ensembles generated from X-ray crystal structures were characterized by network centrality and community analysis. Mutual information related collective motions to local fragment dynamics encoded with a structural alphabet. Implicit solvent tCONCOORD conformational ensembles revealed the dynamic architecture of inactive kinase domains was co-opted in the activated dimer but the network hub shifted from the nucleotide binding cleft to the captured peptide. Explicit solvent molecular dynamics (MD) showed nucleotide and substrate binding determinants formed coupled nodes in long-range signal relays between regulatory peptides in the dimer. Strain in the extended captured peptide was balanced by reduced flexibility of the receiver kinase C-lobe core. The relays were organized around a hydrophobic patch between the captured peptide and a key binding helix. The human mutations aligned along the relays. Thus, these mutations could disrupt the allosteric network alternatively, or in addition, to altered binding affinities. Non-binding protein sectors distant from the binding sites mediated the allosteric signalling; providing possible targets for inhibitor design. Phosphorylation of the peptide modulated the dielectric of its binding pocket to strengthen the patch, non-binding sectors, domain interface and temporal correlations between parallel relays. These results provide the molecular details underlying the reported positive kinase cooperativity to enrich the discussion on how autonomous activation by phosphorylation leads to long-term behavioural effects.
| S-EPMC6576796 | biostudies-literature
Project description:BackgroundToxoplasma gondii is an obligate intracellular parasite of the phylum Apicomplexa and a major pathogen of animals and immunocompromised humans, in whom it causes encephalitis. Understanding the mechanism of tachyzoite invasion is important for the discovery of new drug targets and may serve as a model for the study of other apicomplexan parasites. We previously showed that Plasmodium falciparum expresses a homolog of human calcium calmodulin-dependent protein kinase (CaMK) that is important for host cell invasion. In this study, to identify novel targets for the treatment of Toxoplasma gondii infection (another apicomplexan parasite), we sought to identify a CaMK-like protein in the T. gondii genome and to characterize its role in the life-cycle of this parasite.MethodsAn in vitro kinase assay was performed to assess the phosphorylation activities of a novel CaMK-like protein in T. gondii by using purified proteins with various concentrations of calcium, calmodulin antagonists, or T. gondii glideosome proteins. Indirect immunofluorescence microscopy was performed to detect the localization of this protein kinase by using the antibodies against this protein and organellar maker proteins of T. gondii.ResultsWe identified a novel CaMK homolog in T. gondii, T. gondii CaMK-related kinase (TgCaMKrk), which exhibits calmodulin-independent autophosphorylation and substrate phosphorylation activity. However, calmodulin antagonists had no effect on its kinase activity. In T. gondii-infected cells, TgCaMKrk localized to the apical ends of extracellular and intracellular tachyzoites. TgCaMKrk phosphorylated TgGAP45 for phosphorylation in vitro.ConclusionsOur data improve our understanding of T. gondii motility and infection, the interaction between parasite protein kinases and glideosomes, and drug targets for protozoan diseases.
| S-EPMC4957278 | biostudies-literature
Project description:Kidney podocytes and their slit diaphragms contribute to prevent urinary protein loss. T cell from patients with systemic lupus erythematosus display increased expression of calcium/calmodulin kinase IV (CaMKIV). Here we evaluated the functional role of CaMKIV in lupus nephritis (LN) using kidney biopsy specimens and human podocyte cell line (AB8/13). We found that exposure of podocytes to IgG from LN patients resulted in entry of IgG into the cytoplasm. CaMKIV expression was found to be increased in podocytes of LN kidney biopsy specimens and exposure to IgG from LN patients. IgG entered podocytes using the FcRn receptor because when podocytes where treated with FcRn siRNA less IgG was found in the cytoplasm. The DNA microarray studies of podocytes exposed to LN IgG revealed that genes that are related to the activation of immune cells or podocyte damage were upregulated. These genes included CD86, CaMKIV, PTPN22, PDE5A, CD47 and MALT1. Interestingly, CD86 expression decreased after silencing CaMKIV in podocytes. Also, in situ hybridization experiments showed that the expression of CD86 was reduced in podocytes from MRL/lpr.camkiv−/− mice. IgG from LN patients may enter podocytes through the FcRn and causes the upregulation of a distinct set of genes which may alter podocyte function. Upregulation of CaMKIV appears to precede that of genes known to be linked to podocyte damage such as CD86. These findings may indicate that inhibition of CaMKIV may prove of clinical use in patients with LN.
2014-08-01 | GSE55768 | GEO