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1.
J Biol Chem ; 300(5): 107267, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38583863

RESUMO

Phospholamban (PLB) is a transmembrane micropeptide that regulates the sarcoplasmic reticulum Ca2+-ATPase (SERCA) in cardiac muscle, but the physical mechanism of this regulation remains poorly understood. PLB reduces the Ca2+ sensitivity of active SERCA, increasing the Ca2+ concentration required for pump cycling. However, PLB does not decrease Ca2+ binding to SERCA when ATP is absent, suggesting PLB does not inhibit SERCA Ca2+ affinity. The prevailing explanation for these seemingly conflicting results is that PLB slows transitions in the SERCA enzymatic cycle associated with Ca2+ binding, altering transport Ca2+ dependence without actually affecting the equilibrium binding affinity of the Ca2+-coordinating sites. Here, we consider another hypothesis, that measurements of Ca2+ binding in the absence of ATP overlook important allosteric effects of nucleotide binding that increase SERCA Ca2+ binding affinity. We speculated that PLB inhibits SERCA by reversing this allostery. To test this, we used a fluorescent SERCA biosensor to quantify the Ca2+ affinity of non-cycling SERCA in the presence and absence of a non-hydrolyzable ATP-analog, AMPPCP. Nucleotide activation increased SERCA Ca2+ affinity, and this effect was reversed by co-expression of PLB. Interestingly, PLB had no effect on Ca2+ affinity in the absence of nucleotide. These results reconcile the previous conflicting observations from ATPase assays versus Ca2+ binding assays. Moreover, structural analysis of SERCA revealed a novel allosteric pathway connecting the ATP- and Ca2+-binding sites. We propose this pathway is disrupted by PLB binding. Thus, PLB reduces the equilibrium Ca2+ affinity of SERCA by interrupting allosteric activation of the pump by ATP.


Assuntos
Proteínas de Ligação ao Cálcio , Cálcio , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático , Animais , Humanos , Trifosfato de Adenosina/metabolismo , Regulação Alostérica , Cálcio/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Proteínas de Ligação ao Cálcio/química , Miocárdio/metabolismo , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/química , Cães , Células HEK293 , Modelos Moleculares , Estrutura Terciária de Proteína
2.
NPJ Digit Med ; 7(1): 59, 2024 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-38499605

RESUMO

Type 1 diabetes (T1D) is a chronic condition characterized by glucose fluctuations. Laboratory studies suggest that cognition is reduced when glucose is very low (hypoglycemia) and very high (hyperglycemia). Until recently, technological limitations prevented researchers from understanding how naturally-occurring glucose fluctuations impact cognitive fluctuations. This study leveraged advances in continuous glucose monitoring (CGM) and cognitive ecological momentary assessment (EMA) to characterize dynamic, within-person associations between glucose and cognition in naturalistic environments. Using CGM and EMA, we obtained intensive longitudinal measurements of glucose and cognition (processing speed, sustained attention) in 200 adults with T1D. First, we used hierarchical Bayesian modeling to estimate dynamic, within-person associations between glucose and cognition. Consistent with laboratory studies, we hypothesized that cognitive performance would be reduced at low and high glucose, reflecting cognitive vulnerability to glucose fluctuations. Second, we used data-driven lasso regression to identify clinical characteristics that predicted individual differences in cognitive vulnerability to glucose fluctuations. Large glucose fluctuations were associated with slower and less accurate processing speed, although slight glucose elevations (relative to person-level means) were associated with faster processing speed. Glucose fluctuations were not related to sustained attention. Seven clinical characteristics predicted individual differences in cognitive vulnerability to glucose fluctuations: age, time in hypoglycemia, lifetime severe hypoglycemic events, microvascular complications, glucose variability, fatigue, and neck circumference. Results establish the impact of glucose on processing speed in naturalistic environments, suggest that minimizing glucose fluctuations is important for optimizing processing speed, and identify several clinical characteristics that may exacerbate cognitive vulnerability to glucose fluctuations.

3.
Biochim Biophys Acta Mol Cell Res ; 1871(4): 119699, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38387507

RESUMO

As the genetic landscape of cardiomyopathies continues to expand, the identification of missense variants in disease-associated genes frequently leads to a classification of variant of uncertain significance (VUS). For the proper reclassification of such variants, functional characterization is an important contributor to the proper assessment of pathogenic potential. Several missense variants in the calcium transport regulatory protein phospholamban have been associated with dilated cardiomyopathy. However, >40 missense variants in this transmembrane peptide are currently known and most remain classified as VUS with little clinical information. Similarly, missense variants in cardiac myosin binding protein have been associated with hypertrophic cardiomyopathy. However, hundreds of variants are known and many have low penetrance and are often found in control populations. Herein, we focused on novel missense variants in phospholamban, an Ala15-Thr variant found in a 4-year-old female and a Pro21-Thr variant found in a 60-year-old female, both with a family history and clinical diagnosis of dilated cardiomyopathy. The patients also harbored a Val896-Met variant in cardiac myosin binding protein. The phospholamban variants caused defects in the function, phosphorylation, and dephosphorylation of this calcium transport regulatory peptide, and we classified these variants as potentially pathogenic. The variant in cardiac myosin binding protein alters the structure of the protein. While this variant has been classified as benign, it has the potential to be a low-risk susceptibility variant because of the structural change in cardiac myosin binding protein. Our studies provide new biochemical evidence for missense variants previously classified as benign or VUS.


Assuntos
Proteínas de Ligação ao Cálcio , Cardiomiopatia Dilatada , Pré-Escolar , Feminino , Humanos , Pessoa de Meia-Idade , Cálcio/metabolismo , Proteínas de Ligação ao Cálcio/genética , Proteínas de Ligação ao Cálcio/metabolismo , Miosinas Cardíacas/genética , Miosinas Cardíacas/metabolismo , Cardiomiopatia Dilatada/diagnóstico , Cardiomiopatia Dilatada/genética , Cardiomiopatia Dilatada/metabolismo , Peptídeos/metabolismo , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo
4.
PNAS Nexus ; 3(1): pgad453, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38222469

RESUMO

The discovery of allosteric modulators is an emerging paradigm in drug discovery, and signal transduction is a subtle and dynamic process that is challenging to characterize. We developed a time-correlated single photon-counting imaging approach to investigate the structural mechanisms for small-molecule activation of the cardiac sarcoplasmic reticulum Ca2+-ATPase, a pharmacologically important pump that transports Ca2+ at the expense of adenosine triphosphate (ATP) hydrolysis. We first tested whether the dissociation of sarcoplasmic reticulum Ca2+-ATPase from its regulatory protein phospholamban is required for small-molecule activation. We found that CDN1163, a validated sarcoplasmic reticulum Ca2+-ATPase activator, does not have significant effects on the stability of the sarcoplasmic reticulum Ca2+-ATPase-phospholamban complex. Time-correlated single photon-counting imaging experiments using the nonhydrolyzable ATP analog ß,γ-Methyleneadenosine 5'-triphosphate (AMP-PCP) showed ATP is an allosteric modulator of sarcoplasmic reticulum Ca2+-ATPase, increasing the fraction of catalytically competent structures at physiologically relevant Ca2+ concentrations. Unlike ATP, CDN1163 alone has no significant effects on the Ca2+-dependent shifts in the structural populations of sarcoplasmic reticulum Ca2+-ATPase, and it does not increase the pump's affinity for Ca2+ ions. However, we found that CDN1163 enhances the ATP-mediated modulatory effects to increase the population of catalytically competent sarcoplasmic reticulum Ca2+-ATPase structures. Importantly, this structural shift occurs within the physiological window of Ca2+ concentrations at which sarcoplasmic reticulum Ca2+-ATPase operates. We demonstrated that ATP is both a substrate and modulator of sarcoplasmic reticulum Ca2+-ATPase and showed that CDN1163 and ATP act synergistically to populate sarcoplasmic reticulum Ca2+-ATPase structures that are primed for phosphorylation. This study provides novel insights into the structural mechanisms for sarcoplasmic reticulum Ca2+-ATPase activation by its substrate and a synthetic allosteric modulator.

5.
J Child Sex Abus ; 33(1): 102-125, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-37994404

RESUMO

This critique alerts practicing professionals of the multiple misleading statements in the recently published article entitled, "A compendium of risk and needs tools for assessing male youths at-risk to and/or who have engaged in sexually abusive behaviors." This critique corrects the erroneous information contained in Jung and Thomas' article, providing current accurate information related to the important distinct differences of available standardized risk assessment tools used in forensic settings with youths who have engaged in sexually abusive behaviors. Erroneous statements by other researchers and authors in the field are also discussed. Forensic cases are distinctively different from others seen in clinical settings, requiring specific knowledge and skill set, a notable distinction not often mentioned in research literature.


Assuntos
Abuso Sexual na Infância , Criança , Humanos , Masculino , Adolescente , Medição de Risco , Agressão , Registros , Comportamento Sexual
6.
Biochim Biophys Acta Mol Cell Res ; 1871(1): 119613, 2024 01.
Artigo em Inglês | MEDLINE | ID: mdl-37918638

RESUMO

Myoregulin (MLN) is a protein that regulates the activity of the sarcoplasmic reticulum Ca2+-ATPase (SERCA) without affecting its affinity for Ca2+. MLN's residue Lys27 is located at a site where other SERCA regulators control Ca2+ affinity. Therefore, we conducted atomistic simulations and ATPase activity experiments to determine whether replacing Lys27 with asparagine, a conserved residue found in various muscle SERCA regulators, would enable MLN to modulate both the Ca2+ affinity and catalytic activity of SERCA. Our findings indicate that replacing Lys27 with Asn significantly enhances the inhibitory potency of MLN, but it does not affect SERCA's affinity for Ca2+. We suggest that the SERCA site modulating Ca2+ affinity also acts as a catalytic activity switch. Therefore, this site is a key element contributing to the functional divergence among homologous SERCA regulators. This study paves the way for future investigations to explore how biological function diverges during the evolution of the SERCA regulator family.


Assuntos
Asparagina , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático , Asparagina/metabolismo , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/genética , Retículo Sarcoplasmático/metabolismo
7.
Biochemistry ; 62(8): 1331-1336, 2023 04 18.
Artigo em Inglês | MEDLINE | ID: mdl-37014032

RESUMO

Myoregulin (MLN) is a member of the regulin family, a group of homologous membrane proteins that bind to and regulate the activity of the sarcoplasmic reticulum Ca2+-ATPase (SERCA). MLN, which is expressed in skeletal muscle, contains an acidic residue in its transmembrane domain. The location of this residue, Asp35, is unusual because the relative occurrence of aspartate is very rare (<0.2%) within the transmembrane helix regions. Therefore, we used atomistic simulations and ATPase activity assays of protein co-reconstitutions to probe the functional role of MLN residue Asp35. These structural and functional studies showed Asp35 has no effects on SERCA's affinity for Ca2+ or the structural integrity of MLN in the lipid bilayer. Instead, Asp35 controls SERCA inhibition by populating a bound-like orientation of MLN. We propose Asp35 provides a functional advantage over other members of the regulin family by populating preexisting MLN conformations required for MLN-specific regulation of SERCA. Overall, this study provides new clues about the evolution and functional divergence of the regulin family and offers novel insights into the functional role of acidic residues in transmembrane protein domains.


Assuntos
Cálcio , Músculo Esquelético , Cálcio/metabolismo , Proteínas de Ligação ao Cálcio/química , Transporte de Íons , Conformação Molecular , Músculo Esquelético/metabolismo , Retículo Sarcoplasmático/química , Retículo Sarcoplasmático/metabolismo , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/química , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Humanos
8.
J Biol Chem ; 299(5): 104681, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-37030504

RESUMO

We report a novel small-molecule screening approach that combines data augmentation and machine learning to identify Food and Drug Administration (FDA)-approved drugs interacting with the calcium pump (Sarcoplasmic reticulum Ca2+-ATPase, SERCA) from skeletal (SERCA1a) and cardiac (SERCA2a) muscle. This approach uses information about small-molecule effectors to map and probe the chemical space of pharmacological targets, thus allowing to screen with high precision large databases of small molecules, including approved and investigational drugs. We chose SERCA because it plays a major role in the excitation-contraction-relaxation cycle in muscle and it represents a major target in both skeletal and cardiac muscle. The machine learning model predicted that SERCA1a and SERCA2a are pharmacological targets for seven statins, a group of FDA-approved 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors used in the clinic as lipid-lowering medications. We validated the machine learning predictions by using in vitro ATPase assays to show that several FDA-approved statins are partial inhibitors of SERCA1a and SERCA2a. Complementary atomistic simulations predict that these drugs bind to two different allosteric sites of the pump. Our findings suggest that SERCA-mediated Ca2+ transport may be targeted by some statins (e.g., atorvastatin), thus providing a molecular pathway to explain statin-associated toxicity reported in the literature. These studies show the applicability of data augmentation and machine learning-based screening as a general platform for the identification of off-target interactions and the applicability of this approach extends to drug discovery.


Assuntos
Inibidores de Hidroximetilglutaril-CoA Redutases , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático , Inibidores de Hidroximetilglutaril-CoA Redutases/farmacologia , Inibidores de Hidroximetilglutaril-CoA Redutases/metabolismo , Miocárdio/enzimologia , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/antagonistas & inibidores , Aprendizado de Máquina
9.
J Child Sex Abus ; 32(3): 379-396, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36935612

RESUMO

This article contends that youth who engage in persistent coarse sexual improprieties and/or, sexually abusive behaviors are too often viewed primarily through a criminological lens, regardless of their age, gender, judicial status, and/or experiences of past trauma/victimization. Such a posture likely falsifies the clinical perception of the individual referred for "treatment." Assessment and interventions for these youth must be holistic and idiosyncratic, considering numerous multiplex developmental variables (i.e., overall human sexual development, gender identity, sexual identity, sexual orientation, erotic development, intimacy deficits, adverse childhood experiences/trauma), as well as sociological and anthropological fundamentals. The lens for assessing and intervening with youth must also include in its focus the constantly changing Zeitgeist, that is, the spirit or the mood of the times. The proposed lens is applicable to all youth, adjudicated and non-adjudicated. Specific considerations are discussed related to those youth with a history of significant child maltreatment who later engage in persistent coarse sexual improprieties and/or sexually abusive behaviors.


Assuntos
Abuso Sexual na Infância , Vítimas de Crime , Criança , Adolescente , Humanos , Masculino , Feminino , Identidade de Gênero , Comportamento Sexual , Agressão
10.
J Child Sex Abus ; 32(2): 133-152, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36797815

RESUMO

This article renews the call by Chaffin and Bonner in 1998 to cease treating youth who engage in sexually abusive behaviors like adult male convicted sex offenders. The author urges that professionals cease imposing an adult-centered convicted sex offender paradigm in assessment and treatment. A new paradigm is advocated that considers sexual developmental and gender issues, along with judicial status in all areas of intervention (i.e., clinical and risk assessment, treatment/service planning, and possible treatment [when needed]). The paradigm is grounded on the Family Lovemap model, a conceptual framework for assessing the youth's bio-physio-psycho-social-sexual and erotic development. Discussed is the evidence-based, developmentally and gender sensitive risk-level tool, MEGA♪ as a viable option for assessing risk for persistent coarse sexual improprieties and sexually abusive behaviors in youth ages 4-19 (adjudicated and non-adjudicated). Selected significant empirical findings are presented from 3,901 youths who were participants in samples of the MEGA♪ validation studies.


Assuntos
Abuso Sexual na Infância , Criminosos , Delitos Sexuais , Criança , Humanos , Masculino , Adolescente , Pré-Escolar , Adulto Jovem , Adulto , Comportamento Sexual , Medição de Risco , Agressão
11.
Crit Rev Food Sci Nutr ; 63(29): 10173-10196, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-35593230

RESUMO

Fermentation has been used since the Early Neolithic period to preserve foods. It has inherent organoleptic and nutritive properties that bestow health benefits, including reducing inflammation and oxidative stress, supporting the growth of salutogenic microbiota, enhancing intestinal mucosal protection and promoting beneficial immunometabolic health effects. The fermentation of food with specific microbiota increases the production salutogenic bioactive compounds that can activate Nrf2 mediated cytoprotective responses and mitigate the effects of the 'diseasome of aging' and its associated inflammageing, which presents as a prominent feature of obesity, type-2 diabetes, cardiovascular and chronic kidney disease. This review discusses the importance of fermented food in improving health span, with special reference to cardiometabolic diseases.


Assuntos
Doenças Cardiovasculares , Alimentos Fermentados , Microbiota , Humanos , Dieta , Obesidade/prevenção & controle , Doenças Cardiovasculares/prevenção & controle , Fermentação
12.
J Endocrinol Invest ; 45(12): 2257-2264, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-35821458

RESUMO

AIM: Women with early-onset gestational diabetes mellitus (GDM) have overall lower gestational weight gain (GWG) compared to those with later-onset GDM, albeit with usually worse maternofetal outcomes. We intent to investigate the association between inadequate GWG and maternofetal outcomes in pregnant women with early-onset GDM. METHODS: We performed a retrospective study of women with early-onset GDM based on the National Registry of GDM. Three study groups were defined according to the recommendations of the Institute of Medicine for GWG: excessive GWG (eGWG), adequate (aGWG) or insufficient (iGWG). RESULTS: A total of 8040 pregnant women were included: 27% (n = 2170) eGWG, 31% (n = 2492) aGWG and 42% (n = 3378) iGWG. Preeclampsia (4.3 vs 3 vs 1.6%, p < 0.001), polyhydramnios (3.1 vs 2.3 vs 1.8%, p = 0.008) and cesarean section (37.4 vs 34.1 vs 29.5%, p < 0.001) were significantly more frequent among women with eGWG. Additionally, there was a higher frequency of macrosomia (8.1 vs 3.6 vs 2.4%, p < 0.001), large-for-gestational-age (8.2 vs 3.7 vs 2.6%, p < 0.001) and birth trauma (2.6 vs 1.5 vs 1.1%, p < 0.001) in this group. On the other hand, fetal death (0.2 vs 0.2 vs 0.5%, p = 0.04), small-for-gestational-age (9 vs 10.3 vs 14.9, p < 0.001) and preterm delivery (5.6 vs 7.1 vs 7.5%, p = 0.03) were more frequent in iGWG group. CONCLUSIONS: Over two-thirds of pregnant women with early-onset GDM had inappropriate GWG, which was significantly associated with adverse maternofetal outcomes. Weight management must be a focus of special attention in women with early-onset GDM, beyond glycemic control, to achieve healthy pregnancy outcomes.


Assuntos
Diabetes Gestacional , Recém-Nascido , Feminino , Gravidez , Humanos , Diabetes Gestacional/epidemiologia , Estudos Retrospectivos , Cesárea , Índice de Massa Corporal , Aumento de Peso , Resultado da Gravidez/epidemiologia
13.
Biochemistry ; 61(14): 1419-1430, 2022 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-35771007

RESUMO

Intracellular calcium signaling is essential for all kingdoms of life. An important part of this process is the sarco-endoplasmic reticulum Ca2+-ATPase (SERCA), which maintains the low cytosolic calcium levels required for intracellular calcium homeostasis. In higher organisms, SERCA is regulated by a series of tissue-specific transmembrane subunits such as phospholamban in cardiac muscles and sarcolipin in skeletal muscles. These regulatory axes are so important for muscle contractility that SERCA, phospholamban, and sarcolipin are practically invariant across mammalian species. With the recent discovery of the arthropod sarcolambans, the family of calcium pump regulatory subunits appears to span more than 550 million years of evolutionary divergence from arthropods to humans. This evolutionary divergence is reflected in the peptide sequences, which vary enormously from one another and only vaguely resemble phospholamban and sarcolipin. The discovery of the sarcolambans allowed us to address two questions. How much sequence variation is tolerated in the regulation of mammalian SERCA activity by the transmembrane peptides? Do divergent peptide sequences mimic phospholamban or sarcolipin in their regulatory activities despite limited sequence similarity? We expressed and purified recombinant sarcolamban peptides from three different arthropods. The peptides were coreconstituted into proteoliposomes with mammalian SERCA1a and the effect of each peptide on the apparent calcium affinity and maximal activity of SERCA was measured. All three peptides were superinhibitors of SERCA, exhibiting either phospholamban-like or sarcolipin-like characteristics. Molecular modeling, protein-protein docking, and molecular dynamics simulations revealed novel features of the divergent peptides and their SERCA regulatory properties.


Assuntos
Cálcio , Retículo Sarcoplasmático , Animais , Cálcio/metabolismo , Sinalização do Cálcio , Proteínas de Ligação ao Cálcio/química , Humanos , Mamíferos/metabolismo , Simulação de Dinâmica Molecular , Proteínas Musculares , Peptídeos/metabolismo , Peptídeos/farmacologia , Proteolipídeos/química , Retículo Sarcoplasmático/metabolismo , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/química
14.
J Biol Chem ; 298(5): 101865, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35339486

RESUMO

The sodium-potassium ATPase (Na/K-ATPase, NKA) establishes ion gradients that facilitate many physiological functions including action potentials and secondary transport processes. NKA comprises a catalytic subunit (alpha) that interacts closely with an essential subunit (beta) and regulatory transmembrane micropeptides called FXYD proteins. In the heart, a key modulatory partner is the FXYD protein phospholemman (PLM, FXYD1), but the stoichiometry of the alpha-beta-PLM regulatory complex is unknown. Here, we used fluorescence lifetime imaging and spectroscopy to investigate the structure, stoichiometry, and affinity of the NKA-regulatory complex. We observed a concentration-dependent binding of the subunits of NKA-PLM regulatory complex, with avid association of the alpha subunit with the essential beta subunit as well as lower affinity alpha-alpha and alpha-PLM interactions. These data provide the first evidence that, in intact live cells, the regulatory complex is composed of two alpha subunits associated with two beta subunits, decorated with two PLM regulatory subunits. Docking and molecular dynamics (MD) simulations generated a structural model of the complex that is consistent with our experimental observations. We propose that alpha-alpha subunit interactions support conformational coupling of the catalytic subunits, which may enhance NKA turnover rate. These observations provide insight into the pathophysiology of heart failure, wherein low NKA expression may be insufficient to support formation of the complete regulatory complex with the stoichiometry (alpha-beta-PLM)2.


Assuntos
Microscopia , ATPase Trocadora de Sódio-Potássio , Membrana Celular/metabolismo , Fosfoproteínas/metabolismo , Fosforilação , Sódio/metabolismo , ATPase Trocadora de Sódio-Potássio/metabolismo
15.
Comput Struct Biotechnol J ; 20: 380-384, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35035790

RESUMO

Phospholamban (PLN) and Sarcolipin (SLN) are homologous membrane proteins that belong to the family of proteins that regulate the activity of the cardiac calcium pump (sarcoplasmic reticulum Ca2+-ATPase, SERCA). PLN and SLN share highly conserved leucine zipper motifs that control self-association; consequently, it has been proposed that both PLN and SLN assemble into stable pentamers in the membrane. In this study, we used molecular dynamics (MD) simulations and Western blot analysis to investigate the precise molecular architecture of the PLN and SLN oligomers. Analysis showed that the PLN pentamer is the predominant oligomer present in mouse ventricles and ventricle-like human iPSC-derived cardiomyocytes, in agreement with the MD simulations showing stable leucine zipper interactions across all protomer-protomer interfaces and MD replicates. Interestingly, we found that the PLN pentamer populates an asymmetric structure of the transmembrane region, which is likely an intrinsic feature of the oligomer in a lipid bilayer. The SLN pentamer is not favorably formed across MD replicates and species of origin; instead, SLN from human and mouse atria primarily populate coexisting dimeric and trimeric states. In contrast to previous studies, our findings indicate that the SLN pentamer is not the predominant oligomeric state populated in the membrane. We conclude that despite their structural homology, PLN and SLN adopt distinct oligomeric states in the membrane. We propose that the distinct oligomeric states populated by PLN and SLN may contribute to tissue-specific SERCA regulation via differences in protomer-oligomer exchange, oligomer-SERCA dynamics, and noise filtering during ß-adrenergic stimulation in the heart.

16.
Sci Rep ; 11(1): 16580, 2021 08 16.
Artigo em Inglês | MEDLINE | ID: mdl-34400719

RESUMO

Membrane proteins constitute a substantial fraction of the human proteome, thus representing a vast source of therapeutic drug targets. Indeed, newly devised technologies now allow targeting "undruggable" regions of membrane proteins to modulate protein function in the cell. Despite the advances in technology, the rapid translation of basic science discoveries into potential drug candidates targeting transmembrane protein domains remains challenging. We address this issue by harmonizing single molecule-based and ensemble-based atomistic simulations of ligand-membrane interactions with patient-derived induced pluripotent stem cell (iPSC)-based experiments to gain insights into drug delivery, cellular efficacy, and safety of molecules directed at membrane proteins. In this study, we interrogated the pharmacological activation of the cardiac Ca2+ pump (Sarcoplasmic reticulum Ca2+-ATPase, SERCA2a) in human iPSC-derived cardiac cells as a proof-of-concept model. The combined computational-experimental approach serves as a platform to explain the differences in the cell-based activity of candidates with similar functional profiles, thus streamlining the identification of drug-like candidates that directly target SERCA2a activation in human cardiac cells. Systematic cell-based studies further showed that a direct SERCA2a activator does not induce cardiotoxic pro-arrhythmogenic events in human cardiac cells, demonstrating that pharmacological stimulation of SERCA2a activity is a safe therapeutic approach targeting the heart. Overall, this novel multiscale platform encompasses organ-specific drug potency, efficacy, and safety, and opens new avenues to accelerate the bench-to-patient research aimed at designing effective therapies directed at membrane protein domains.


Assuntos
Proteínas de Membrana/efeitos dos fármacos , Terapia de Alvo Molecular/métodos , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/efeitos dos fármacos , Bibliotecas de Moléculas Pequenas/uso terapêutico , Animais , Ativação Enzimática/efeitos dos fármacos , Células Gigantes/enzimologia , Humanos , Células-Tronco Pluripotentes Induzidas/enzimologia , Microssomos/enzimologia , Simulação de Dinâmica Molecular , Estrutura Molecular , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/enzimologia , Fosfatidilcolinas , Domínios Proteicos/efeitos dos fármacos , Retículo Sarcoplasmático/enzimologia , Bibliotecas de Moléculas Pequenas/efeitos adversos , Bibliotecas de Moléculas Pequenas/farmacologia , Suínos , Água
17.
Elife ; 102021 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-34075877

RESUMO

The sarco-plasmic reticulum calcium pump (SERCA) plays a critical role in the contraction-relaxation cycle of muscle. In cardiac muscle, SERCA is regulated by the inhibitor phospholamban. A new regulator, dwarf open reading frame (DWORF), has been reported to displace phospholamban from SERCA. Here, we show that DWORF is a direct activator of SERCA, increasing its turnover rate in the absence of phospholamban. Measurement of in-cell calcium dynamics supports this observation and demonstrates that DWORF increases SERCA-dependent calcium reuptake. These functional observations reveal opposing effects of DWORF activation and phospholamban inhibition of SERCA. To gain mechanistic insight into SERCA activation, fluorescence resonance energy transfer experiments revealed that DWORF has a higher affinity for SERCA in the presence of calcium. Molecular modeling and molecular dynamics simulations provide a model for DWORF activation of SERCA, where DWORF modulates the membrane bilayer and stabilizes the conformations of SERCA that predominate during elevated cytosolic calcium.


Assuntos
Sinalização do Cálcio , Cálcio/metabolismo , Peptídeos/metabolismo , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Retículo Sarcoplasmático/enzimologia , Proteínas de Ligação ao Cálcio/metabolismo , Ativação Enzimática , Células HEK293 , Humanos , Simulação de Dinâmica Molecular , Peptídeos/química , Peptídeos/genética , Conformação Proteica , Retículo Sarcoplasmático/genética , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/química , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/genética , Relação Estrutura-Atividade , Fatores de Tempo
18.
Int J Mol Sci ; 22(7)2021 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-33805255

RESUMO

The calcium pump (sarco/endoplasmic reticulum Ca2+-ATPase, SERCA) plays a major role in calcium homeostasis in muscle cells by clearing cytosolic Ca2+ during muscle relaxation. Active Ca2+ transport by SERCA involves the structural transition from a low-Ca2+ affinity E2 state toward a high-Ca2+ affinity E1 state of the pump. This structural transition is accompanied by the countertransport of protons to stabilize the negative charge and maintain the structural integrity of the transport sites and partially compensate for the positive charges of the two Ca2+ ions passing through the membrane. X-ray crystallography studies have suggested that a hydrated pore located at the C-terminal domain of SERCA serves as a conduit for proton countertransport, but the existence and function of this pathway have not yet been fully characterized. We used atomistic simulations to demonstrate that in the protonated E2 state and the absence of initially bound water molecules, the C-terminal pore becomes hydrated in the nanosecond timescale. Hydration of the C-terminal pore is accompanied by the formation of water wires that connect the transport sites with the cytosol. Water wires are known as ubiquitous proton-transport devices in biological systems, thus supporting the notion that the C-terminal domain serves as a conduit for proton release. Additional simulations showed that the release of a single proton from the transport sites induces bending of transmembrane helix M5 and the interaction between residues Arg762 and Ser915. These structural changes create a physical barrier against full hydration of the pore and prevent the formation of hydrogen-bonded water wires once proton transport has occurred through this pore. Together, these findings support the notion that the C-terminal proton release pathway is a functional element of SERCA and also provide a mechanistic model for its operation in the catalytic cycle of the pump.


Assuntos
Cálcio/metabolismo , Simulação de Dinâmica Molecular , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Humanos , Transporte de Íons , Conformação Proteica
19.
Acta Diabetol ; 58(9): 1209-1215, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33856590

RESUMO

AIM: To clarify whether mild first trimester hyperglycaemia (characteristic of early-onset GDM) is associated with higher incidence of congenital malformations and other adverse fetomaternal outcomes compared to women with second trimester hyperglycaemia (later-onset GDM). DESIGN AND METHODS: We analyzed the Portuguese National GDM database, containing data collected between 2011 and 2017. Two study groups were defined: Group 1-Women with GDM diagnosed during the first trimester (with fasting glycemia ≥ 92 and < 126 mg/dL); Group 2-Women with GDM diagnosed after the first 12 weeks of gestation, with either fasting glycemia or oral glucose tolerance test, according to the International Association of Pregnancy and Diabetes Study Group criteria. The fetomaternal characteristics of each group were compared. RESULTS: A total of 18.518 pregnant women diagnosed with GDM were included which 34.4% of them belonged to Group 1. Pregnant women from this group were significantly younger and had a higher median BMI than the women from the other group. Overall, there was no significant differences in maternal morbidity parameters between groups. Non-evolutive pregnancies were significantly more frequent along the present gestation in the group 1 (1.1% vs. 0.1%, p < 0.001), as was fetal death (0.6% vs. 0.2%, p < 0.001). Congenital malformations did not differ significantly between groups (3.2% vs. 2.8%, p = 0.155). CONCLUSIONS: The mild near conceptional hyperglycaemic state characteristic of an early-onset GDM seems to be associated with an increased prevalence of non-evolutive pregnancies and foetal deaths when compared to later-onset GDM.


Assuntos
Diabetes Gestacional , Hiperglicemia , Glicemia , Diabetes Gestacional/diagnóstico , Diabetes Gestacional/epidemiologia , Feminino , Teste de Tolerância a Glucose , Humanos , Hiperglicemia/complicações , Hiperglicemia/epidemiologia , Gravidez , Primeiro Trimestre da Gravidez , Segundo Trimestre da Gravidez
20.
J Child Sex Abus ; 30(7): 765-784, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33899696

RESUMO

Evaluated is a recently developed tool, the Youth Needs and Progress Scale (YNPS). Reported is the surprisingly palpable lack of adherence to scientific standards. A demonstrable absence of attention and accordance to scientific methods related to research and developing psychometrics is evident, that is, taking a colander approach when constructing the tool. The rudimentary steps of this project were described by Kang et al. (2019) and subsequently critiqued by this author. Significant concerns previously delineated were not addressed, but rather crystalized in a substantial U.S. federally tax funded grant for a substandard tool. These are described in this article (i.e., lack of adequate literature review, citing selective research findings, referencing face validity tools, problematic research design). The key concern is the reliance on risk recidivism tools (J-SOAP-II and ERASOR), partially based on adult research and empirically shown to have inconsistently performed in risk assessment studies.


Assuntos
Abuso Sexual na Infância , Delinquência Juvenil , Delitos Sexuais , Adolescente , Adulto , Criança , Humanos , Psicometria , Reprodutibilidade dos Testes , Medição de Risco
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