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1.
Nutr Res ; 122: 101-112, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38215571

RESUMO

Obesity is a health problem that involves fat accumulation in adipose and other tissues and causes cell dysfunction. Long-chain saturated fatty acids can induce and propagate inflammation, which may also contribute to the brain alterations found in individuals with obesity. Fatty acids accumulate in astrocytes in situations of blood‒brain barrier disruption, such as inflammatory conditions. Furthermore, the increase in tumor necrosis factor-alpha (TNF-α) and S100 calcium-binding protein B (S100B) secretion is considered an essential component of the inflammatory response. We hypothesize that through their action on astrocytes, long-chain saturated fatty acids mediate some of the brain alterations observed in individuals with obesity. Here, we investigate the direct effect of long-chain fatty acids on astrocytes. Primary astrocyte cultures were incubated for 24 hours with myristic, palmitic, stearic, linoleic, or α-linolenic acids (25-100 µM). All saturated fatty acids tested led to an increase in TNF-α secretion, but only palmitic acid, one of the most common fatty acids, increased S100B secretion, indicating that S100B secretion is probably not caused in response to TNF-α release. Palmitic acid also caused nuclear migration of nuclear factor kappa B. Long-chain saturated fatty acids did not alter cell viability or redox status. In conclusion, long-chain saturated fatty acids can alter astrocytic homeostasis and may contribute to brain disorders associated with obesity, such as neuroinflammation.


Assuntos
Ácido Palmítico , Fator de Necrose Tumoral alfa , Humanos , Ácido Palmítico/farmacologia , Fator de Necrose Tumoral alfa/metabolismo , Astrócitos/metabolismo , Ácidos Graxos/farmacologia , Ácidos Graxos/metabolismo , Obesidade , Subunidade beta da Proteína Ligante de Cálcio S100/farmacologia
2.
Front Microbiol ; 13: 895526, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35875570

RESUMO

Rhizobium leguminosarum synthesizes an acidic polysaccharide mostly secreted to the extracellular medium, known as exopolysaccharide (EPS) and partially retained on the bacterial surface as a capsular polysaccharide (CPS). Rap proteins, extracellular protein substrates of the PrsDE type I secretion system (TISS), share at least one Ra/CHDL (cadherin-like) domain and are involved in biofilm matrix development either through cleaving the polysaccharide by Ply glycanases or by altering the bacterial adhesive properties. It was shown that the absence or excess of extracellular RapA2 (a monomeric CPS calcium-binding lectin) alters the biofilm matrix's properties. Here, we show evidence of the role of a new Rap protein, RapD, which comprises an N-terminal Ra/CHDL domain and a C-terminal region of unknown function. RapD was completely released to the extracellular medium and co-secreted with the other Rap proteins in a PrsDE-dependent manner. Furthermore, high levels of RapD secretion were found in biofilms under conditions that favor EPS production. Interestingly, size exclusion chromatography of the EPS produced by the ΔrapA2ΔrapD double mutant showed a profile of EPS molecules of smaller sizes than those of the single mutants and the wild type strain, suggesting that both RapA2 and RapD proteins influence EPS processing on the cell surface. Biophysical studies showed that calcium triggers proper folding and multimerization of recombinant RapD. Besides, further conformational changes were observed in the presence of EPS. Enzyme-Linked ImmunoSorbent Assay (ELISA) and Binding Inhibition Assays (BIA) indicated that RapD specifically binds the EPS and that galactose residues would be involved in this interaction. Taken together, these observations indicate that RapD is a biofilm matrix-associated multimeric protein that influences the properties of the EPS, the main structural component of the rhizobial biofilm.

3.
Arch Biochem Biophys ; 714: 109065, 2021 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-34710387

RESUMO

EF-hand is a common motif in Ca2+-binding proteins, some of which present a conformational change upon Ca2+-binding, a relevant property for signal transduction. In the present work, we investigated the behavior of Calbindin D9k, a modulator protein with a high affinity for Ca2+ but structurally insensitive to its presence. Its non-canoncal N-terminal EF-hand was replaced by chimeric motifs, containing increasing structural elements from the sensor troponin C SCIII motif. We demonstrated that the loop and helix II were the necessary elements for a conformational change promoted by calcium in chimeric Calbindin D9k. Fusion of the isolated chimeric motifs to an activity reporter gene showed the loop as the minimal element to promote a conformational change. The discrepancy between these results is discussed in the light of inter-motif interactions and helix I participation in modulating the Ca2+ affinity and restricting motif conformation.


Assuntos
Cálcio/metabolismo , Proteína G de Ligação ao Cálcio S100/metabolismo , Sequência de Aminoácidos , Dicroísmo Circular , Motivos EF Hand , Modelos Moleculares , Ligação Proteica , Conformação Proteica , Proteína G de Ligação ao Cálcio S100/química
4.
Arch. med ; 21(1): 24-34, 2021/01/03.
Artigo em Espanhol | LILACS | ID: biblio-1148354

RESUMO

Objective: to determine the presence and distribution of markers of the epithelialmesenchymal transition (EMT) (S-100A4 and alpha-smooth muscle actin-α-SMA) in gingival tissues of patients affected by Gingival hypertrophy (GH) due to orthodontics.GH is an exaggerated increase in gingival tissue whose pathogenesis is unknown. However, it has been reported that the epithelial-mesenchymal transition as a process involved in other types of GH. Materials and methods: descriptive study that included the analysis of gingival tissues of healthy individuals (n = 6) and patients with GH by orthodontic treatment (n = 6). Before gingival surgery, the patients underwent a periodontal hygiene phase. The gingival tissue samples obtained were processed and embedded in paraffin. The cuts were made with a microtome and deposited on polysine adhesion slides. Histological hematoxylin-eosin staining was performed.The identification and location of S-100A4 and α-SMA markers was determined by immunohistochemistry with monoclonal antibodies. The reading of the findings was carried out by oral pathologists. Results: in healthy individuals, an S100A4 label was observed in Langerhans cells, while α-SMA was identified in the vascular endothelium of all samples analysed. However, in patients with GH due to orthodontics, they registered an intense staining of S100A4 in gingival fibroblasts, Langerhans cells, vascular endothelium, and areas adjacent to the rupture of blood vessel. α-SMA expression in GO was detected in the vascular endothelium and gingival fibroblasts. Conclusion: the differential immunostaining of EMT markers in gingival tissues of patients with orthodontic GH suggests an eventual role of EMT in the pathogenesis of this pathology..Au


Objective: to determine the presence and distribution of markers of the epithelialmesenchymal transition (EMT) (S-100A4 and alpha-smooth muscle actin-α-SMA) in gingival tissues of patients affected by Gingival hypertrophy (GH) due to orthodontics. GH is an exaggerated increase in gingival tissue whose pathogenesis is unknown. However, it has been reported that the epithelial-mesenchymal transition as a process involved in other types of GH. Materials and methods: descriptive study that included the analysis of gingival tissues of healthy individuals (n = 6) and patients with GH by orthodontic treatment (n = 6). Before gingival surgery, the patients underwent a periodontal hygiene phase. The gingival tissue samples obtained were processed and embedded in paraffin. The cuts were made with a microtome and deposited on polysine adhesion slides. Histological hematoxylin-eosin staining was performed. The identification and location of S-100A4 and α-SMA markers was determined by immunohistochemistry with monoclonal antibodies. The reading of the findings was carried out by oral pathologists. Results: in healthy individuals, an S100A4 label was observed in Langerhans cells, while α-SMA was identified in the vascular endothelium of all samples analysed. However, in patients with GH due to orthodontics, they registered an intense staining of S100A4 in gingival fibroblasts, Langerhans cells, vascular endothelium, and areas adjacent to the rupture of blood vessel. α-SMA expression in GO was detected in the vascular endothelium and gingival fibroblasts. Conclusion: the differential immunostaining of EMT markers in gingival tissues of patients with orthodontic GH suggests an eventual role of EMT in the pathogenesis of this pathology..Au


Assuntos
Humanos , Pacientes , Tecidos , Proteína A4 de Ligação a Cálcio da Família S100
5.
mSphere ; 5(5)2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32907953

RESUMO

Intracellular calcium (Ca2+) is crucial for signal transduction in Cryptococcus neoformans, the major cause of fatal fungal meningitis. The calcineurin pathway is the only Ca2+-requiring signaling cascade implicated in cryptococcal stress adaptation and virulence, with Ca2+ binding mediated by the EF-hand domains of the Ca2+ sensor protein calmodulin. In this study, we identified the cryptococcal ortholog of neuronal calcium sensor 1 (Ncs1) as a member of the EF-hand superfamily. We demonstrated that Ncs1 has a role in Ca2+ homeostasis under stress and nonstress conditions, as the ncs1Δ mutant is sensitive to a high Ca2+ concentration and has an elevated basal Ca2+ level. Furthermore, NCS1 expression is induced by Ca2+, with the Ncs1 protein adopting a punctate subcellular distribution. We also demonstrate that, in contrast to the case with Saccharomyces cerevisiae, NCS1 expression in C. neoformans is regulated by the calcineurin pathway via the transcription factor Crz1, as NCS1 expression is reduced by FK506 treatment and CRZ1 deletion. Moreover, the ncs1Δ mutant shares a high temperature and high Ca2+ sensitivity phenotype with the calcineurin and calmodulin mutants (cna1Δ and cam1Δ), and the NCS1 promoter contains two calcineurin/Crz1-dependent response elements (CDRE1). Ncs1 deficiency coincided with reduced growth, characterized by delayed bud emergence and aberrant cell division, and hypovirulence in a mouse infection model. In summary, our data show that Ncs1 has a significant role as a Ca2+ sensor in C. neoformans, working with calcineurin to regulate Ca2+ homeostasis and, consequently, promote fungal growth and virulence.IMPORTANCECryptococcus neoformans is the major cause of fungal meningitis in HIV-infected patients. Several studies have highlighted the important contributions of Ca2+ signaling and homeostasis to the virulence of C. neoformans Here, we identify the cryptococcal ortholog of neuronal calcium sensor 1 (Ncs1) and demonstrate its role in Ca2+ homeostasis, bud emergence, cell cycle progression, and virulence. We also show that Ncs1 function is regulated by the calcineurin/Crz1 signaling cascade. Our work provides evidence of a link between Ca2+ homeostasis and cell cycle progression in C. neoformans.


Assuntos
Calcineurina/genética , Proteínas de Ligação ao Cálcio/genética , Divisão Celular/genética , Cryptococcus neoformans/genética , Cryptococcus neoformans/patogenicidade , Proteínas Sensoras de Cálcio Neuronal/genética , Neuropeptídeos/genética , Animais , Cryptococcus neoformans/química , Feminino , Proteínas Fúngicas/genética , Regulação Fúngica da Expressão Gênica , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Transdução de Sinais , Virulência/genética
6.
Microbiol Res ; 235: 126470, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32247916

RESUMO

Leptospirosis is a global re-emerging zoonosis, caused by pathogenic bacteria of the genus Leptospira. Humans are infected mainly through contact with contaminated water or soil. The understanding of the molecular mechanisms of leptospirosis through the characterization of unknown outer membrane proteins may contribute to the development of new treatments, diagnostic methods and vaccines. We have identified using bioinformatics analysis a protein that is encoded by the gene LIC10774, predicted to be localized at the leptospiral outer membrane and exhibit beta-roll folding. Surface exposure was confirmed by flow cytometry, ELISA and immunofluorescence-based confocal microscopy. Through circular dichroism spectroscopy and hydrophobic dye binding we have shown that rLIC10774 binds calcium ions, which imposes changes to secondary and tertiary structures. The recombinant protein was capable of binding to several host extracellular matrix and serum components. Therefore, we describe LIC10774 as a calcium-binding protein exposed in the outer surface of pathogenic leptospires with possible multifunctional roles in adhesion to host tissues, evasion of the immune system and participation in dissemination processes during leptospirosis. In addition, we hypothesize that the calcium binding is important for temperature-dependent functional roles during leptospirosis.


Assuntos
Proteínas da Membrana Bacteriana Externa/metabolismo , Cálcio/metabolismo , Interações Hospedeiro-Patógeno , Leptospira interrogans/genética , Animais , Aderência Bacteriana , Proteínas da Membrana Bacteriana Externa/genética , Clonagem Molecular , Biologia Computacional , Feminino , Humanos , Leptospira interrogans/patogenicidade , Camundongos , Camundongos Endogâmicos BALB C , Ligação Proteica , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia
7.
Microbiol Res, v. 235, 126470, may. 2020
Artigo em Inglês | Sec. Est. Saúde SP, SESSP-IBPROD, Sec. Est. Saúde SP | ID: bud-3001

RESUMO

Leptospirosis is a global re-emerging zoonosis, caused by pathogenic bacteria of the genus Leptospira. Humans are infected mainly through contact with contaminated water or soil. The understanding of the molecular mechanisms of leptospirosis through the characterization of unknown outer membrane proteins may contribute to the development of new treatments, diagnostic methods and vaccines. We have identified using bioinformatics analysis a protein that is encoded by the gene LIC10774, predicted to be localized at the leptospiral outer membrane and exhibit beta-roll folding. Surface exposure was confirmed by flow cytometry, ELISA and immunofluorescence-based confocal microscopy. Through circular dichroism spectroscopy and hydrophobic dye binding we have shown that rLIC10774 binds calcium ions, which imposes changes to secondary and tertiary structures. The recombinant protein was capable of binding to several host extracellular matrix and serum components. Therefore, we describe LIC10774 as a calcium-binding protein exposed in the outer surface of pathogenic leptospires with possible multifunctional roles in adhesion to host tissues, evasion of the immune system and participation in dissemination processes during leptospirosis. In addition, we hypothesize that the calcium binding is important for temperature-dependent functional roles during leptospirosis

8.
Neural Regen Res ; 13(11): 1945-1952, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30233068

RESUMO

Emerging evidence has suggested global histone H4 acetylation status plays an important role in neural plasticity. For instance, the imbalance of this epigenetic marker has been hypothesized as a key factor for the development and progression of several neurological diseases. Likewise, astrocytic reactivity - a well-known process that markedly influences the tissue remodeling after a central nervous system injury - is crucial for tissue remodeling after spinal cord injury (SCI). However, the linkage between the above-mentioned mechanisms after SCI remains poorly understood. We sought to investigate the relation between both glial fibrillary acidic protein (GFAP) and S100 calcium-binding protein B (S100B) (astrocytic reactivity classical markers) and global histone H4 acetylation levels. Sixty-one male Wistar rats (aged ~3 months) were divided into the following groups: sham; 6 hours post-SCI; 24 hours post-SCI; 48 hours post-SCI; 72 hours post-SCI; and 7 days post-SCI. The results suggested that GFAP, but not S100B was associated with global histone H4 acetylation levels. Moreover, global histone H4 acetylation levels exhibited a complex pattern after SCI, encompassing at least three clearly defined phases (first phase: no changes in the 6, 24 and 48 hours post-SCI groups; second phase: increased levels in the 72 hours post-SCI group; and a third phase: return to levels similar to control in the 7 days post-SCI group). Overall, these findings suggest global H4 acetylation levels exhibit distinct patterns of expression during the first week post-SCI, which may be associated with GFAP levels in the perilesional tissue. Current data encourage studies using H4 acetylation as a possible biomarker for tissue remodeling after spinal cord injury.

9.
Parasitol Res ; 117(4): 1035-1041, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29404745

RESUMO

Giardia intestinalis is a parasite that inhabits the small intestine of humans and other mammals, causing a disease that can manifest itself with acute diarrhea. This parasite is an early divergent eukaryote with a compact genome and a life cycle composed of two distinct cell types: the trophozoite, the replicative form, and the cyst, the infectious form. Signal transduction pathways implicated in differentiation processes of G. intestinalis are largely unknown. Calcium, considered an essential messenger in cell signaling, has been shown to regulate a myriad of key cell processes including metabolism, motility, and exocytosis, among other important functions, through calcium-binding proteins (CaBPs). The most important and largest family of CaBPs is the EF-hand protein family. To investigate the nature of calcium signaling pathways present in this protozoan, an in silico analysis of the genome to identify genes encoding EF-hand proteins was undertaken. Twenty-eight sequences containing EF-hand domains were found; most of which have only a pair of domains, and half of the sequences were divergent or unique to Giardia. In addition, the transcription pattern for eight genes encoding EF-hand proteins was assessed during encystation. It was found that all the genes were differentially transcribed suggesting a different function in this process. The in silico results suggest that in G. intestinalis, calcium is involved in the regulation of protein phosphorylation through kinases and phosphatases.


Assuntos
Sinalização do Cálcio/genética , Proteínas de Ligação ao Cálcio/genética , Motivos EF Hand/genética , Giardia lamblia/genética , Animais , Cálcio/química , Sinalização do Cálcio/fisiologia , Genoma de Protozoário/genética , Giardia lamblia/metabolismo , Giardíase/parasitologia , Humanos , Fosforilação , Trofozoítos/metabolismo
10.
J Biol Chem ; 292(6): 2379-2394, 2017 02 10.
Artigo em Inglês | MEDLINE | ID: mdl-28049727

RESUMO

Hypertrophic cardiomyopathy (HCM) is one of the most common cardiomyopathies and a major cause of sudden death in young athletes. The Ca2+ sensor of the sarcomere, cardiac troponin C (cTnC), plays an important role in regulating muscle contraction. Although several cardiomyopathy-causing mutations have been identified in cTnC, the limited information about their structural defects has been mapped to the HCM phenotype. Here, we used high-resolution electron-spray ionization mass spectrometry (ESI-MS), Carr-Purcell-Meiboom-Gill relaxation dispersion (CPMG-RD), and affinity measurements of cTnC for the thin filament in reconstituted papillary muscles to provide evidence of an allosteric mechanism in mutant cTnC that may play a role to the HCM phenotype. We showed that the D145E mutation leads to altered dynamics on a µs-ms time scale and deactivates both of the divalent cation-binding sites of the cTnC C-domain. CPMG-RD captured a low populated protein-folding conformation triggered by the Glu-145 replacement of Asp. Paradoxically, although D145E C-domain was unable to bind Ca2+, these changes along its backbone allowed it to attach more firmly to thin filaments than the wild-type isoform, providing evidence for an allosteric response of the Ca2+-binding site II in the N-domain. Our findings explain how the effects of an HCM mutation in the C-domain reflect up into the N-domain to cause an increase of Ca2+ affinity in site II, thus opening up new insights into the HCM phenotype.


Assuntos
Mutação , Miocárdio/metabolismo , Troponina C/metabolismo , Regulação Alostérica , Animais , Cardiomiopatia Hipertrófica/metabolismo , Eletroforese em Gel de Poliacrilamida , Humanos , Interações Hidrofóbicas e Hidrofílicas , Conformação Proteica , Ratos , Ratos Wistar , Análise Espectral/métodos , Troponina C/química , Troponina C/genética
11.
Biochim Biophys Acta ; 1834(12): 2823-31, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24157662

RESUMO

Centrins are calcium-binding proteins associated with microtubules organizing centers. Members of two divergent subfamilies of centrins were found in the aquatic fungus Blastocladiella emersonii, contrasting with the occurrence of only one member known for the better explored terrestrial fungi. BeCen1 shows greatest identity with human centrins HsCen1, HsCen2 and green algae centrin CrCenp, while BeCen3 records largest identity with human centrin HsCen3 and yeast centrin Cdc31p. Following the discovery of this unique feature, BeCen1 and BeCen3 centrins were produced to study whether these proteins had distinct features upon calcium binding. Circular dichroism showed opposite calcium binding effects on the α-helix arrangement of the secondary structure. The spectra indicated a decrease in α-helix signal for holo-BeCen1 contrasting with an increase for holo-BeCen3. In addition, only BeCen1 refolds after being de-natured. The fluorescence emission of the hydrophobic probe ANS increases for both proteins likely due to hydrophobic exposure, however, only BeCen1 presents a clear blue shift when calcium is added. ITC experiments identified four calcium binding sites for both proteins. In contrast to calcium binding to BeCen1, which is mainly endothermic, binding to BeCen3 is mainly exothermic. Light-scattering evidenced the formation of large particles in solution for BeCen1 and BeCen3 at temperatures above 30°C and 40°C, respectively. Atomic force microscopy confirmed the presence of supramolecular structures, which differ in the compactness and branching degree. Binding of calcium leads to different structural changes in BeCen1 and BeCen3 and the thermodynamic characteristics of the interaction also differ.


Assuntos
Blastocladiella/química , Cálcio/química , Proteínas Fúngicas/química , Dobramento de Proteína , Combinação Trimetoprima e Sulfametoxazol/química , Blastocladiella/metabolismo , Cálcio/metabolismo , Dicroísmo Circular , Proteínas Fúngicas/metabolismo , Humanos , Microscopia de Força Atômica , Ligação Proteica , Isoformas de Proteínas/química , Isoformas de Proteínas/metabolismo , Estrutura Secundária de Proteína , Termodinâmica , Combinação Trimetoprima e Sulfametoxazol/metabolismo
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