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Advances in Experimental Medicine and... 2019New strategies are critically needed to counter uncontrolled periodontal infection and inflammation in obesity-associated type 2 diabetes (T2D). However, mechanisms that... (Review)
Review
New strategies are critically needed to counter uncontrolled periodontal infection and inflammation in obesity-associated type 2 diabetes (T2D). However, mechanisms that explain the relationship between periodontitis (PD) and T2D remain poorly understood. Several lines of evidence indicate that destructive immune responses potentiate periodontitis (PD) in T2D. B cells are abundant in periodontal lesions, and our data show that B cells are required for PD in obese/insulin resistant but not lean/normoglycemic mice. In mice and in people, T2D-primed B cells supported Th17 cytokine profiles, but B cells had a modest effect on T-cell function in samples from normoglycemic individuals. Given the recently appreciated importance of Th17 cells in PD outside a T2D milieu, our data raise the possibility that B cells indirectly promote T2D-potentiated PD through support of Th17 cells, which in turn directly promote PD.Data herein thereby suggest unexpected mechanisms that explain the clinical observation that T2D potentiates PD.
Topics: Animals; Diabetes Mellitus, Type 2; Inflammation; Mice; Obesity; Periodontitis; Th17 Cells
PubMed: 31732933
DOI: 10.1007/978-3-030-28524-1_4 -
European Journal of Medicinal Chemistry Nov 2023Multidrug-resistant Escherichia coli is a continuously growing worldwide public health problem, in which the well-known AcrAB-TolC tripartite RND efflux pump is a...
Multidrug-resistant Escherichia coli is a continuously growing worldwide public health problem, in which the well-known AcrAB-TolC tripartite RND efflux pump is a critical driver. We have previously described pyridylpiperazines as a novel class of allosteric inhibitors of E. coli AcrB which bind to a unique site in the protein transmembrane domain, allowing for the potentiation of antibiotic activity. Here, we show a rational optimization of pyridylpiperazines by modifying three specific derivatization points of the pyridine core to improve the potency and the pharmacokinetic properties of this chemical series. In particular, this work found that the introduction of a primary amine to the pyridine through ester (29, BDM91270) or oxadiazole (44, BDM91514) based linkers allowed for analogues with improved antibiotic boosting potency through AcrB inhibition. In vitro studies, using genetically engineered mutants, showed that this improvement in potency is mediated through novel interactions with distal acidic residues of the AcrB binding pocket. Of the two leads, compound 44 was found to have favorable physico-chemical properties and suitable plasma and microsomal stability. Together, this work expands the current structure-activity relationship data on pyridylpiperazine efflux pump inhibitors, and provides a promising step towards future in vivo proof of concept of pyridylpiperazines as antibiotic potentiators.
Topics: Escherichia coli; Escherichia coli Proteins; Anti-Bacterial Agents; Pyridines; Multidrug Resistance-Associated Proteins; Carrier Proteins
PubMed: 37459793
DOI: 10.1016/j.ejmech.2023.115630 -
The Journal of Biological Chemistry Mar 2016Potentiated variants of Hsp104, a protein disaggregase from yeast, can dissolve protein aggregates connected to neurodegenerative diseases such as Parkinson disease and...
Potentiated variants of Hsp104, a protein disaggregase from yeast, can dissolve protein aggregates connected to neurodegenerative diseases such as Parkinson disease and amyotrophic lateral sclerosis. However, the mechanisms underlying Hsp104 potentiation remain incompletely defined. Here, we establish that 2-3 subunits of the Hsp104 hexamer must bear an A503V potentiating mutation to elicit enhanced disaggregase activity in the absence of Hsp70. We also define the ATPase and substrate-binding modalities needed for potentiated Hsp104(A503V) activity in vitro and in vivo. Hsp104(A503V) disaggregase activity is strongly inhibited by the Y257A mutation that disrupts substrate binding to the nucleotide-binding domain 1 (NBD1) pore loop and is abolished by the Y662A mutation that disrupts substrate binding to the NBD2 pore loop. Intriguingly, Hsp104(A503V) disaggregase activity responds to mixtures of ATP and adenosine 5'-(γ-thio)-triphosphate (a slowly hydrolyzable ATP analogue) differently from Hsp104. Indeed, an altered pattern of ATP hydrolysis and altered allosteric signaling between NBD1 and NBD2 are likely critical for potentiation. Hsp104(A503V) variants bearing inactivating Walker A or Walker B mutations in both NBDs are inoperative. Unexpectedly, however, Hsp104(A503V) retains potentiated activity upon introduction of sensor-1 mutations that reduce ATP hydrolysis at NBD1 (T317A) or NBD2 (N728A). Hsp104(T317A/A503V) and Hsp104(A503V/N728A) rescue TDP-43 (TAR DNA-binding protein 43), FUS (fused in sarcoma), and α-synuclein toxicity in yeast. Thus, Hsp104(A503V) displays a more robust activity that is unperturbed by sensor-1 mutations that greatly reduce Hsp104 activity in vivo. Indeed, ATPase activity at NBD1 or NBD2 is sufficient for Hsp104 potentiation. Our findings will empower design of ameliorated therapeutic disaggregases for various neurodegenerative diseases.
Topics: Adenosine Triphosphate; Binding Sites; Heat-Shock Proteins; Mutation, Missense; Protein Binding; Protein Folding; RNA-Binding Protein FUS; Recombinant Proteins; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; alpha-Synuclein
PubMed: 26747608
DOI: 10.1074/jbc.M115.707976 -
Expert Opinion on Investigational Drugs 2016Twenty-six years after the identification of the gene responsible for cystic fibrosis (CF), controversies still surround the pathogenesis of the disease that continues... (Review)
Review
INTRODUCTION
Twenty-six years after the identification of the gene responsible for cystic fibrosis (CF), controversies still surround the pathogenesis of the disease that continues to burden and shorten lives. Therefore, finding effective therapeutic strategies that target the basic defect of CF is crucially needed.
AREAS COVERED
This review offers a comprehensive survey of fundamental therapies in early stages of development for the treatment of CF. The first part describes recent strategies targeting the basic defect either at the gene or at the transcript level. The second part summarizes a panel of novel strategies targeting protein repair. The third part reports strategies targeting non-CFTR channels.
EXPERT OPINION
Recent major breakthroughs in CF therapy have been made, raising hope to find a cure for CF. Apart from Vertex corrector and potentiator molecules (lumacaftor, ivacaftor, VX-661) and from ataluren, used to correct nonsense mutations, most compounds being currently tested are in very early (I-II) phases of development and definitive clinical results are keenly expected. Among the broad list of molecules and strategies being tested, the QR-010 compound and inhibitors of phosphodiesterase type 5 (sildenafil, vardenafil) could reveal a strong potentiality as therapeutic candidates to cure CF.
Topics: Animals; Cystic Fibrosis; Cystic Fibrosis Transmembrane Conductance Regulator; Humans; Mutation; Transcription, Genetic
PubMed: 26878157
DOI: 10.1517/13543784.2016.1154041 -
Neuroscience Letters Jan 2018Recent studies have suggested the involvement of some metabolic hormones in memory formation and synaptic plasticity. Insulin dysfunction is known as an essential...
Recent studies have suggested the involvement of some metabolic hormones in memory formation and synaptic plasticity. Insulin dysfunction is known as an essential process in the pathogenesis of sporadic Alzheimer's disease (AD). In this study we examined whether adiponectin (ADN), as an insulin-sensitizing adipokine, could affect hippocampal synaptic plasticity. Field potential recordings were performed on intracerebroventricular (icv) cannulated urethane anesthetized rats. After baseline recording from dentate gyrus (DG) and 10min prior to high/low frequency stimulation (HFS/LFS), 10μl icv ADN (600nm) were injected. The slope of field excitatory postsynaptic potentials (fEPSP) and the amplitude of population spikes (PS) were recorded in response to perforanth path (PP) stimulation. Paired pulse stimuli and ADN injection without any stimulation protocols were also evaluated. Application of ADN before HFS increased PS amplitude recorded in DG significantly (P≤0.05) in comparison to HFS only group. ADN suppressed the potency of LFS to induce long-term depression (LTD), causing a significant difference between fEPSP slope (P≤0.05) and PS amplitude (P≤0.01) between ADN+LFS and ADN group. Paired pulse stimuli applied at 20ms intervals showed more paired pulse facilitation (PPF), when applied after ADN (P≤0.05). ADN induced a chemical long-term potentiation (LTP) in which fEPSP slope and PS amplitude increased significantly (P≤0.01 and P≤0.05, respectively). It is concluded that ADN is able to potentiate the HFS-induced LTP and suppress LFS-induced LTD. ADN caused a chemical LTP, when applied without any tetanic protocol. ADN may enhance the presynaptic release probability.
Topics: Adiponectin; Animals; Dentate Gyrus; Electric Stimulation; Excitatory Postsynaptic Potentials; Injections, Intraventricular; Long-Term Potentiation; Long-Term Synaptic Depression; Male; Membrane Glycoproteins; Neuronal Plasticity; Rats, Wistar; Receptors, Interleukin-1
PubMed: 29079430
DOI: 10.1016/j.neulet.2017.10.042 -
European Journal of Medicinal Chemistry Oct 2020Cystic fibrosis (CF) is a genetic disorder produced by the loss of function of CFTR, a main chloride channel involved in transepithelial salt and water transport. CFTR... (Review)
Review
Cystic fibrosis (CF) is a genetic disorder produced by the loss of function of CFTR, a main chloride channel involved in transepithelial salt and water transport. CFTR function can be rescued by small molecules called "potentiators" which increase gating activity of CFTR on epithelial surfaces. High throughput screening (HTS) assays allowed the identification of new chemical entities endowed with potentiator properties, further improved through medicinal chemistry optimization. In this review, the most relevant classes of CFTR potentiators developed in the last decade were explored, focusing on structure-activity relationships (SAR) of the different chemical entities, as a useful tool for the improvement of their pharmacological activity.
Topics: Aminophenols; Cystic Fibrosis Transmembrane Conductance Regulator; Glycine; Humans; Mutation; Quinolones; Small Molecule Libraries; Structure-Activity Relationship; Triazoles
PubMed: 32898816
DOI: 10.1016/j.ejmech.2020.112631 -
Frontiers in Fungal Biology 2022Fluconazole-resistant (FLZR-CP) outbreaks are a growing public health concern and have been reported in numerous countries. Patients infected with FLZR-CP isolates show...
Fluconazole-resistant (FLZR-CP) outbreaks are a growing public health concern and have been reported in numerous countries. Patients infected with FLZR-CP isolates show fluconazole therapeutic failure and have a significantly increased mortality rate. Because fluconazole is the most widely used antifungal agent in most regions with outbreaks, it is paramount to restore its antifungal activity. Milbemycin oxim (MOX), a well-known canine endectocide, is a potent efflux pump inhibitor that significantly potentiates the activity of fluconazole against FLZR . and . However, the FLZ-MOX combination has not been tested against FLZR-CP isolates, nor is it known whether MOX may also potentiate the activity of echinocandins, a different class of antifungal drugs. Furthermore, the extent of involvement of efflux pumps and and ergosterol biosynthesis enzyme and their link with gain-of-function (GOF) mutations in their transcription regulators (, , and ) are poorly characterized among FLZR-CP isolates. We analyzed 25 C. isolates collected from outbreaks in Turkey and Brazil by determining the expression levels of , , and , examining the presence of potential GOF mutations in their transcriptional regulators, and assessing the antifungal activity of FLZ-MOX and micafungin-MOX against FLZR and multidrug-resistant (MDR) . isolates. was found to be universally induced by fluconazole in all isolates, while expression of was unchanged. Whereas mutations in and were not detected, was overexpressed in three Brazilian FLZR-CP isolates, which also carried a novel mutation. Of these three isolates, one showed increased basal expression of , while the other two overexpressed only in the presence of fluconazole. Interestingly, MOX showed promising antifungal activity against FLZR isolates, reducing the FLZ MIC 8- to 32-fold. However, the MOX and micafungin combination did not exert activity against an MDR . isolate. Collectively, our study documents that the mechanisms underpinning FLZR are region specific, where mutations were the sole mechanism of FLZR in Turkish FLZR-CP isolates, while simultaneous overexpression of was observed in some Brazilian counterparts. Moreover, MOX and fluconazole showed potent synergistic activity, while the MOX-micafungin combination showed no synergy.
PubMed: 37746198
DOI: 10.3389/ffunb.2022.906681 -
BioRxiv : the Preprint Server For... Mar 2024While the involvement of actin polymerization in cell migration is well-established, much less is known about the role of transmembrane water flow in cell motility....
While the involvement of actin polymerization in cell migration is well-established, much less is known about the role of transmembrane water flow in cell motility. Here, we investigate the role of water influx in a prototypical migrating cell, the neutrophil, which undergoes rapid, directed movement to sites of injury and infection. Chemoattractant exposure both increases cell volume and potentiates migration, but the causal link between these processes is not known. We combine single cell volume measurements and a genome-wide CRISPR screen to identify the regulators of chemoattractant-induced neutrophil swelling, including NHE1, AE2, PI3K-gamma, and CA2. Through NHE1 inhibition in primary human neutrophils, we show that cell swelling is both necessary and sufficient for the potentiation of migration following chemoattractant stimulation. Our data demonstrate that chemoattractant-driven cell swelling complements cytoskeletal rearrangements to enhance migration speed.
PubMed: 37292824
DOI: 10.1101/2023.05.15.540704 -
Journal of Applied Physiology... Oct 2023A potentiating conditioning contraction (CC) has been shown to increase silent period duration, an index of corticospinal inhibition; however, it is unknown if the CC...
A potentiating conditioning contraction (CC) has been shown to increase silent period duration, an index of corticospinal inhibition; however, it is unknown if the CC must induce potentiation for corticospinal inhibition to increase. Ten healthy, young adults (four females) completed this study to assess potentiation and silent period (SP) duration before and after four types of CCs: voluntary and electrically evoked maximal CCs to optimize potentiation, and voluntary and electrically evoked submaximal CCs (∼40% of maximal voluntary force) that induced minimal potentiation. Stimulation was applied to the ulnar nerve to evoke twitches for the assessment of potentiation and to evoke tetanic CCs of the first dorsal interosseous muscle. The SP was elicited by applying transcranial magnetic stimulation to the motor cortex during brief contractions at 25% of maximal voluntary force. Changes to twitch force and SP duration were not different for voluntary and tetanic contractions, so data were pooled. Twitch force increased by 81.2 ± 35.7% ( < 0.001) and 3.2 ± 6.5% ( = 0.039) following maximal and submaximal CCs, respectively. The SP was prolonged following maximal (12.6 ± 6.3%; < 0.001) and submaximal (4.8 ± 4.9%; < 0.001) CCs. Correlations between post-CC twitch force and SP duration were not significant for maximal or submaximal conditions ( = -0.068; = 0.067; ≥ 0.780, respectively). Duration of the SP increased not only following maximal-intensity CCs but also after submaximal-intensity CCs that induced virtually no potentiation (∼3%). Thus, we suggest that corticospinal inhibition is not directly related to mechanisms of muscle potentiation per se, but, rather, the level of muscle contraction likely mediates feedback from large diameter afferents that affect the SP. The transcranial magnetic stimulation-induced silent period reflects a transient state of corticospinal inhibition that is influenced by recent history of muscle activation, which may include an effect of potentiation. We demonstrate that silent period duration increases following both voluntary and electrically evoked maximal and submaximal conditioning contractions, even though the latter intensity produced virtually no muscle potentiation. Feedback from group Ia and Ib muscle afferents is proposed as the cause of the increased corticospinal inhibition.
Topics: Female; Young Adult; Humans; Muscle, Skeletal; Muscle Contraction; Transcranial Magnetic Stimulation; Electric Stimulation; Electromyography; Evoked Potentials, Motor; Muscle Fatigue; Isometric Contraction
PubMed: 37616335
DOI: 10.1152/japplphysiol.00206.2023 -
Clinical Neurophysiology : Official... Jan 2016Paired associative stimulation (PAS) has been used to study normal and abnormal cortical plasticity. However, a normative review of PAS effects has not been provided so... (Review)
Review
OBJECTIVE
Paired associative stimulation (PAS) has been used to study normal and abnormal cortical plasticity. However, a normative review of PAS effects has not been provided so far. To this end, the magnitude and time course of PAS protocols was systematically evaluated here.
METHODS
A literature search in PubMed using the search term paired associative stimulation was conducted. Main inclusion criteria were that experiments were conducted in primary motor cortex of healthy volunteers without motor training before intervention and motor evoked potentials as primary outcome measure. This search yielded in total 104 experiments, which were analyzed to examine the potentiating (PASLTP) and depressing effects of PAS (PASLTD) on cortical excitability levels in healthy volunteers.
RESULTS
PASLTP induces reliable and stable potentiating effects (maximum ± standard error 38.5 ± 3.3%) on cortical excitability levels up to 90 min. PASLTP was most effective when applied at frequencies of 0.05 and 0.2 Hz. Analyses of the PASLTD studies demonstrated reliable and stable depression of cortical excitability levels up to 120 min (maximum ± standard error -23.0 ± 1.9%)
CONCLUSIONS
PAS significantly modulates cortical excitability. The potentiating effects of PASLTP are stronger than the depressing effects for PASLTD.
SIGNIFICANCE
Present findings offer normative insights into the magnitude and time course of PASLTP and PASLTD-induced changes in cortical excitability levels.
Topics: Association Learning; Evoked Potentials, Motor; Humans; Mental Disorders; Motor Cortex; Neuronal Plasticity; Neuropsychiatry; Time Factors; Transcranial Magnetic Stimulation; Treatment Outcome
PubMed: 26024981
DOI: 10.1016/j.clinph.2015.04.072