RESUMEN
Students from public urban secondary schools in the United States are often academically underprepared for post-secondary education. There are multiple social and structural factors contributing to this including living in communities where there are high rates of poverty, insufficient funding for public urban schools, and lack of rigor in their curriculum. Urban public post-secondary institutions struggle to bridge the gap to support students who are underprepared and in need of educational, financial, and social assistance. The purpose of this paper is to describe a partnership that was created between a public urban high school and a neighboring public urban university to address the issues underrepresented racially and ethnically (URE) diverse students encounter in order to not only better prepare them for the transition to post-secondary education, but to help them succeed once they arrive on campus. This partnership demonstrates that community cooperation to bridge the gap to support students who are underprepared is possible and benefits everyone involved. Preparing urban students for the successful transition to post-secondary education, particularly in the area of health professions can have a long-term impact on reducing racial inequities in health care.
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Grupos Minoritarios , Motivación , Curriculum , Empleos en Salud , Humanos , Estudiantes , Estados UnidosRESUMEN
BACKGROUND: College retention rates continue to be a national issue in the United States. Solutions to decrease attrition have not been adequately tested in the nursing student population. PURPOSE: The purpose of this study was to investigate the benefits of a peer-mentoring program in a baccalaureate nursing program from the perspectives of both the mentor and mentee. METHODS: Electronic surveys were used to evaluate the impact of a peer-mentoring program. RESULTS: Responses showed the peer-mentoring program to be beneficial academically, personally, and professionally. A large majority (89%-96%) of mentees agreed or strongly agreed with the positive effects of the peer-mentoring program, whereas all of the mentors agreed or strongly agreed with the positive effects. CONCLUSIONS: Peer mentoring was found to be advantageous for both the mentees and mentors.
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Actitud del Personal de Salud , Bachillerato en Enfermería/organización & administración , Tutoría/métodos , Mentores/psicología , Grupo Paritario , Estudiantes de Enfermería/psicología , Humanos , Investigación en Educación de Enfermería , Investigación en Evaluación de Enfermería , Encuestas y CuestionariosRESUMEN
Interprofessional collaborative practice (IPCP) was recommended to improve siloed and fragmented patient care. The Institute of Medicine recommended nurses lead this change through innovative models of patient-centered care and IPCP participation. One strategy to improve patient experience is rounding. This project presents a nurse-led interprofessional bedside rounding model to improve communication and collaboration between providers and with patients on a complex inpatient unit. Outcomes were analyzed using Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) scores to examine patient experience. Postimplementation results demonstrate an increase in HCAHPS patient experience scores for this patient population above hospital and national average.
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Relaciones Interprofesionales , Atención de Enfermería/normas , Personal de Enfermería en Hospital/educación , Atención Dirigida al Paciente/normas , Guías de Práctica Clínica como Asunto , Rondas de Enseñanza/normas , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Personal de Enfermería en Hospital/psicología , Médicos/psicologíaRESUMEN
BACKGROUND: The lack of diversity in the nursing profession could be an outcome of unconscious biases. Forums allowing the personal reflection and discourse of these unconscious biases are needed in order for a diverse and inclusive learning environment to exist. PURPOSE: The purpose of this study was to describe the experiences of students, staff, faculty members, and guests participating in a forum on diversity and inclusion. METHODS: An exploratory design was used to understand the experiences of college of nursing students, staff, faculty members, and guests who participated in a diversity and inclusion intervention sponsored by the college of nursing's Diversity Advisory Council. Attendees to 12 diversity book club, movie night, and speaker series' sessions completed a program evaluation tool. Responses to open-ended items were analyzed using a constant comparative analysis method.Responses from 197 participants were analyzed. Eight book club, seven movie night, and six speaker series' themes were derived from the data including Humanness is Universal, Personal Connection, The Problem, Awareness of Disparity, Make a Difference, and No Change. DISCUSSION: Participants at each session critically dialogued about their conscious and unconscious biases. The study findings show that participants also were able to document changes to their knowledge, attitudes, and behaviors in relation to the historically oppressed populations focused on during the intervention activities. CONCLUSION: Education entertainment as used in this study was a valuable mechanism for hosting conversations about diversity and inclusion.
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Actitud del Personal de Salud , Diversidad Cultural , Bachillerato en Enfermería/organización & administración , Docentes de Enfermería/psicología , Estudiantes de Enfermería/psicología , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Investigación en Educación de Enfermería , OhioRESUMEN
BACKGROUND: Summer bridges facilitate the transition from high school to college. Although many schools employ summer bridges, few have published outcomes. This article's purpose is to share preconceptions of college by underrepresented and disadvantaged nursing students and describe important elements and long-term impact of a summer bridge, a component of the Leadership 2.0 program. METHOD: A longitudinal study design was used to collect baseline, short-term, and long-term post-summer bridge data. Methods included pre- and postsurveys, interviews, and focus groups. RESULTS: After bridge completion, students felt more prepared for the nursing program. Students ranked socialization components as most important. The summer bridge had lasting impact through the first year, where grade point average and retention of underrepresented and disadvantaged bridge students was comparable to the majority first-year students. CONCLUSION: The summer bridge was effective in preparing nursing students for the first year of college. Through holistic evaluation, unique aspects of socialization critical to student success were uncovered.
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Grupos Minoritarios/psicología , Estudiantes de Enfermería/psicología , Poblaciones Vulnerables/psicología , Diversidad Cultural , Bachillerato en Enfermería , Femenino , Humanos , Liderazgo , Estudios Longitudinales , Masculino , Grupos Minoritarios/estadística & datos numéricos , Investigación en Educación de Enfermería , Investigación en Evaluación de Enfermería , Ohio , Investigación Cualitativa , Estudiantes de Enfermería/estadística & datos numéricos , Poblaciones Vulnerables/estadística & datos numéricosRESUMEN
BACKGROUND: Innovative strategies may support the Institute of Medicine's recommendation to increase the number of doctorally prepared nurses by 50% by 2020. Moreover, strategies implemented may increase the number and diversity of Doctor of Philosophy (PhD)-prepared nurses in particular. METHOD: The purpose of this article is to describe the approaches used by one college of nursing to enact a research-doctorate pipeline initiative to inspire a diverse pool of undergraduate students to consider pursuing a PhD degree. Principles that served as the foundation for this pipeline initiative are identified. RESULTS: Sixteen undergraduate students, with varying degrees of research interest, participated in this initiative. Students contributed an average of 35 hours as full members of research teams, and 94% completed the experience. Students with initial low interest in research reported enhanced interest after participation. Overall student experiences were positive and influenced future career plans. CONCLUSION: Lessons learned and future steps for the pipeline initiative are presented.
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Bachillerato en Enfermería , Educación de Postgrado en Enfermería , Investigación en Enfermería , Selección de ProfesiónRESUMEN
A hallmark of human and experimental heart failure is deficient sarcoplasmic reticulum (SR) Ca-uptake reflecting impaired contractile function. This is at least partially attributed to dephosphorylation of phospholamban by increased protein phosphatase 1 (PP1) activity. Indeed inhibition of PP1 by transgenic overexpression or gene-transfer of constitutively active inhibitor-1 improved Ca-cycling, preserved function and decreased fibrosis in small and large animal models of heart failure, suggesting that inhibitor-1 may represent a potential therapeutic target. We recently identified a novel human polymorphism (G109E) in the inhibitor-1 gene with a frequency of 7% in either normal or heart failure patients. Transgenic mice, harboring cardiac-specific expression of G109E inhibitor-1, exhibited decreases in contractility, Ca-kinetics and SR Ca-load. These depressive effects were relieved by isoproterenol stimulation. Furthermore, stress conditions (2Hz +/- Iso) induced increases in Ca-sparks, Ca-waves (60% of G109E versus 20% in wild types) and after-contractions (76% of G109E versus 23% of wild types) in mutant cardiomyocytes. Similar findings were obtained by acute expression of the G109E variant in adult cardiomyocytes in the absence or presence of endogenous inhibitor-1. The underlying mechanisms included reduced binding of mutant inhibitor-1 to PP1, increased PP1 activity, and dephosphorylation of phospholamban at Ser16 and Thr17. However, phosphorylation of the ryanodine receptor at Ser2808 was not altered while phosphorylation at Ser2814 was increased, consistent with increased activation of Ca/calmodulin-dependent protein kinase II (CaMKII), promoting aberrant SR Ca-release. Parallel in vivo studies revealed that mutant mice developed ventricular ectopy and complex ventricular arrhythmias (including bigeminy, trigeminy and ventricular tachycardia), when challenged with isoproterenol. Inhibition of CaMKII activity by KN-93 prevented the increased propensity to arrhythmias. These findings suggest that the human G109E inhibitor-1 variant impairs SR Ca-cycling and promotes arrhythmogenesis under stress conditions, which may present an additional insult in the compromised function of heart failure carriers.
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Arritmias Cardíacas/genética , Arritmias Cardíacas/fisiopatología , Polimorfismo de Nucleótido Simple/genética , Proteínas/genética , Animales , Calcio/metabolismo , Señalización del Calcio/genética , Proteínas de Unión al Calcio/metabolismo , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/metabolismo , Catecolaminas/farmacología , Diástole/efectos de los fármacos , Corazón/efectos de los fármacos , Corazón/fisiopatología , Humanos , Isoproterenol/farmacología , Cinética , Ratones Transgénicos , Contracción Miocárdica/efectos de los fármacos , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Fosforilación/efectos de los fármacos , Proteínas/metabolismo , Ratas , Retículo Sarcoplasmático/efectos de los fármacos , Retículo Sarcoplasmático/metabolismo , Intercambiador de Sodio-Calcio/metabolismoRESUMEN
Arterial myocytes express α1-catalytic subunit isoform Na(+) pumps (75-80% of total), which are ouabain resistant in rodents, and high ouabain affinity α2-Na(+) pumps. Mice with globally reduced α2-pumps (but not α1-pumps), mice with mutant ouabain-resistant α2-pumps, and mice with a smooth muscle (SM)-specific α2-transgene (α2 (SM-Tg)) that induces overexpression all have altered blood pressure (BP) phenotypes. We generated α2 (SM-DN) mice with SM-specific α2 (not α1) reduction (>50%) using nonfunctional dominant negative (DN) α2. We compared α2 (SM-DN) and α2 (SM-Tg) mice to controls to determine how arterial SM α2-pumps affect vasoconstriction and BP. α2 (SM-DN) mice had elevated basal mean BP (mean BP by telemetry: 117 ± 4 vs. 106 ± 1 mmHg, n = 7/7, P < 0.01) and enhanced BP responses to chronic ANG II infusion (240 ng·kg(-1)·min(-1)) and high (6%) NaCl. Several arterial Ca(2+) transporters, including Na(+)/Ca(2+) exchanger 1 (NCX1) and sarcoplasmic reticulum and plasma membrane Ca(2+) pumps [sarco(endo)plasmic reticulum Ca(2+)-ATPase 2 (SERCA2) and plasma membrane Ca(2+)-ATPase 1 (PMCA1)], were also reduced (>50%). α2 (SM-DN) mouse isolated small arteries had reduced myogenic reactivity, perhaps because of reduced Ca(2+) transporter expression. In contrast, α2 (SM-Tg) mouse aortas overexpressed α2 (>2-fold), NCX1, SERCA2, and PMCA1 (43). α2 (SM-Tg) mice had reduced basal mean BP (104 ± 1 vs. 109 ± 2 mmHg, n = 15/9, P < 0.02) and attenuated BP responses to chronic ANG II (300-400 ng·kg(-1)·min(-1)) with or without 2% NaCl but normal myogenic reactivity. NCX1 expression was inversely related to basal BP in SM-α2 engineered mice but was directly related in SM-NCX1 engineered mice. NCX1, which usually mediates arterial Ca(2+) entry, and α2-Na(+) pumps colocalize at plasma membrane-sarcoplasmic reticulum junctions and functionally couple via the local Na(+) gradient to help regulate cell Ca(2+). Altered Ca(2+) transporter expression in SM-α2 engineered mice apparently compensates to minimize Ca(2+) overload (α2 (SM-DN)) or depletion (α2 (SM-Tg)) and attenuate BP changes. In contrast, Ca(2+) transporter upregulation, observed in many rodent hypertension models, should enhance Ca(2+) entry and signaling and contribute significantly to BP elevation.
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Arterias/metabolismo , Presión Sanguínea , Músculo Liso Vascular/metabolismo , ATPasa Intercambiadora de Sodio-Potasio/metabolismo , Angiotensina II/farmacología , Animales , Arterias/fisiología , Ratones , Células Musculares/efectos de los fármacos , Células Musculares/metabolismo , Músculo Liso Vascular/citología , Músculo Liso Vascular/fisiología , ATPasas Transportadoras de Calcio de la Membrana Plasmática/genética , ATPasas Transportadoras de Calcio de la Membrana Plasmática/metabolismo , Subunidades de Proteína/genética , Subunidades de Proteína/metabolismo , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/genética , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/metabolismo , Intercambiador de Sodio-Calcio/genética , Intercambiador de Sodio-Calcio/metabolismo , ATPasa Intercambiadora de Sodio-Potasio/genéticaRESUMEN
AIMS: Impaired sarcoplasmic reticulum (SR) Ca(2+) cycling and depressed contractility, a hallmark of human and experimental heart failure, has been partially attributed to increased protein phosphatase 1 (PP-1) activity, associated with down-regulation of its endogenous inhibitor-1. The levels and activity of inhibitor-1 are reduced in failing hearts, contributing to dephosphorylation and inactivation of key calcium cycling proteins. Therefore, we investigated the mechanisms that mediate decreases in inhibitor-1 by post-transcriptional modification. METHODS AND RESULTS: Bioinformatics revealed that 17 human microRNAs may serve as modulators of inhibitor-1. However, real-time PCR analysis identified only one of these microRNAs, miR-765, as being increased in human failing hearts concomitant with decreased inhibitor-1 levels. Expression of miR-765 in HEK293 cells or mouse ventricular myocytes confirmed suppression of inhibitor-1 levels through binding of this miR-765 to the 3'-untranslated region of inhibitor-1 mRNA. To determine the functional significance of miR-765 in Ca(2+) cycling, pri-miR-765 as well as a non-translated nucleotide sequence (miR-Ctrl) were expressed in adult mouse ventricular myocytes. The inhibitor-1 expression levels were decreased, accompanied by enhanced PP-1 activity in the miR-765 cardiomyocytes, and these reflected depressed contractile mechanics and Ca(2+) transients, compared with the miR-Ctrl group. The depressive effects were associated with decreases in the phosphorylation of phospholamban and SR Ca(2+) load. These miR-765 negative inotropic effects were abrogated in inhibitor-1-deficient cardiomyocytes, suggesting its apparent specificity for inhibitor-1. CONCLUSIONS: miR-765 levels are increased in human failing hearts. Such increases may contribute to depressed cardiac function through reduced inhibitor-1 expression and enhanced PP-1 activity, associated with reduced SR Ca(2+) load.
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Insuficiencia Cardíaca/fisiopatología , Péptidos y Proteínas de Señalización Intracelular/metabolismo , MicroARNs/fisiología , Contracción Miocárdica/fisiología , Regulación hacia Arriba/fisiología , Animales , Western Blotting , Calcio/metabolismo , Células Cultivadas , Humanos , Ratones , Reacción en Cadena en Tiempo Real de la PolimerasaRESUMEN
Impaired sarcoplasmic reticulum calcium cycling and depressed contractility are key characteristics in heart failure. Defects in sarcoplasmic reticulum function are characterized by decreased SERCA2a Ca-transport that is partially attributable to dephosphorylation of its regulator phospholamban by increased protein phosphatase 1 activity. Inhibition of protein phosphatase 1 through activation of its endogenous inhibitor-1 has been shown to enhance cardiac Ca-handling and contractility as well as protect from pathological stress remodeling in young mice. In this study, we assessed the long-term effects of inducible expression of constitutively active inhibitor-1 in the adult heart and followed function and remodeling through the aging process, up to 20 months. Mice with inhibitor-1 had normal survival and similar function to WTs. There was no overt remodeling as evidenced by measures of left ventricular end-systolic and diastolic diameters and posterior wall dimensions, heart weight to tibia length ratio, and histology. Higher phosphorylation of phospholamban at both Ser16 and Thr17 was maintained in aged hearts with active inhibitor-1, potentially offsetting the effects of elevated Ser2815-phosphorylation in ryanodine receptor, as there were no increases in arrhythmias under stress conditions in 20-month old mice. Furthermore, long-term expression of active inhibitor-1 via recombinant adeno-associated virus type 9 gene transfer in rats with pressure-overload induced heart failure improved function and prevented remodeling, associated with increased phosphorylation of phospholamban at Ser16 and Thr17. Thus, chronic inhibition of protein phosphatase 1, through increases in active inhibitor-1, does not accelerate age-related cardiomyopathy and gene transfer of this molecule in vivo improves function and halts remodeling in the long term.
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Envejecimiento/metabolismo , Proteínas de Unión al Calcio/metabolismo , Insuficiencia Cardíaca/metabolismo , Miocardio/metabolismo , Proteínas/metabolismo , Remodelación Ventricular , Envejecimiento/genética , Envejecimiento/patología , Animales , Calcio/metabolismo , Proteínas de Unión al Calcio/genética , Cardiomiopatías/genética , Cardiomiopatías/metabolismo , Cardiomiopatías/patología , Insuficiencia Cardíaca/genética , Insuficiencia Cardíaca/patología , Ratones , Ratones Transgénicos , Miocardio/patología , Fosforilación/genética , Proteínas/genética , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/genética , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/metabolismoRESUMEN
AIMS: Junctin and triadin are calsequestrin-binding proteins that regulate sarcoplasmic reticulum (SR) Ca(2+) release by interacting with the ryanodine receptor. The levels of these proteins are significantly down-regulated in failing human hearts. However, the significance of such decreases is currently unknown. Here, we addressed the functional role of these accessory proteins in the heart's responses to ischaemia/reperfusion (I/R) injury. METHODS AND RESULTS: Isolated mouse hearts were subjected to global I/R, and contractile parameters were assessed in wild-type (WT), junctin-knockout (JKO), and triadin-knockout (TKO) hearts. Both JKO and TKO were associated with significantly depressed post-I/R contractile recovery. However, ablation of triadin resulted in the most severe post-I/R phenotype. The additional contractile impairment of TKO hearts was not related to a mitochondrial death pathway, but attributed to endoplasmic reticulum (ER) stress-mediated apoptosis. Activation of the X-box-binding protein-1 and transcriptional up-regulation of C/EBP-homologous protein (CHOP) provided a molecular mechanism of caspase-12-dependent apoptosis in myocytes. In addition, elevation of cytosolic Ca(2+) during reperfusion was associated with the activation of calpain proteases and troponin I breakdown. Accordingly, treatment with the calpain inhibitor MDL-28170 significantly ameliorated post-I/R impairment of contractile recovery in intact hearts. CONCLUSION: These findings indicate that deficiency of either junctin or triadin impairs the contractile recovery in post-ischaemic hearts, which appears to be primarily attributed to increased ER stress and activation of calpain.
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Proteínas de Unión al Calcio/metabolismo , Calcio/metabolismo , Calpaína/metabolismo , Proteínas Portadoras/metabolismo , Dipéptidos/farmacología , Proteínas de la Membrana/metabolismo , Oxigenasas de Función Mixta/metabolismo , Proteínas Musculares/metabolismo , Infarto del Miocardio/metabolismo , Daño por Reperfusión/metabolismo , Animales , Apoptosis , Western Blotting , Señalización del Calcio , Proteínas de Unión al Calcio/genética , Calpaína/genética , Calsecuestrina/genética , Calsecuestrina/metabolismo , Proteínas Portadoras/genética , Inhibidores de Cisteína Proteinasa/farmacología , Inhibidores de Cisteína Proteinasa/uso terapéutico , Dipéptidos/uso terapéutico , Humanos , Proteínas de la Membrana/genética , Ratones , Oxigenasas de Función Mixta/genética , Proteínas Musculares/genética , Contracción Miocárdica/fisiología , Infarto del Miocardio/tratamiento farmacológico , Daño por Reperfusión/complicacionesRESUMEN
Depressed Ca-handling in cardiomyocytes is frequently attributed to impaired sarcoplasmic reticulum (SR) function in human and experimental heart failure. Phospholamban (PLN) is a key regulator of SR and cardiac function, and PLN mutations in humans have been associated with dilated cardiomyopathy (DCM). We previously reported the deletion of the highly conserved amino acid residue arginine 14 (nucleic acids 39, 40 and 41) in DCM patients. This basic amino acid is important in maintaining the upstream consensus sequence for PKA phosphorylation of Ser 16 in PLN. To assess the function of this mutant PLN, we introduced the PLN-R14Del in cardiac myocytes of the PLN null mouse. Transgenic lines expressing mutant PLN-R14Del at similar protein levels to wild types exhibited no inhibition of the initial rates of oxalate-facilitated SR Ca uptake compared to PLN-knockouts (PLN-KO). The contractile parameters and Ca-kinetics also remained highly stimulated in PLN-R14Del cardiomyocytes, similar to PLN-KO, and isoproterenol did not further stimulate these hyper-contractile basal parameters. Consistent with the lack of inhibition on SR Ca-transport and contractility, confocal microscopy indicated that the PLN-R14Del failed to co-localize with SERCA2a. Moreover, PLN-R14Del did not co-immunoprecipitate with SERCA2a (as did WT-PLN), but rather co-immunoprecipitated with the sarcolemmal Na/K-ATPase (NKA) and stimulated NKA activity. In addition, studies in HEK cells indicated significant fluorescence resonance energy transfer between PLN-R14Del-YFP and NKAα1-CFP, but not with the NKA regulator phospholemman. Despite the enhanced cardiac function in PLN-R14Del hearts (as in PLN-knockouts), there was cardiac hypertrophy (unlike PLN-KO) coupled with activation of Akt and the MAPK pathways. Thus, human PLN-R14Del is misrouted to the sarcolemma, in the absence of endogenous PLN, and alters NKA activity, leading to cardiac remodeling.
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Proteínas de Unión al Calcio/genética , Proteínas de Unión al Calcio/metabolismo , Membrana Celular/metabolismo , Eliminación de Secuencia , ATPasa Intercambiadora de Sodio-Potasio/metabolismo , Animales , Calcio/metabolismo , Cardiomegalia/genética , Cardiomegalia/metabolismo , Cardiomegalia/patología , Activación Enzimática/genética , Humanos , Masculino , Ratones , Ratones Transgénicos , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Unión Proteica , Transporte de Proteínas , Retículo Sarcoplasmático/metabolismo , Transducción de Señal , Remodelación Ventricular/genéticaRESUMEN
BACKGROUND: Heat shock proteins (Hsp) are known to enhance cell survival under various stress conditions. In the heart, the small Hsp20 has emerged as a key mediator of protection against apoptosis, remodeling, and ischemia/reperfusion injury. Moreover, Hsp20 has been implicated in modulation of cardiac contractility ex vivo. The objective of this study was to determine the in vivo role of Hsp20 in the heart and the mechanisms underlying its regulatory effects in calcium (Ca) cycling. METHODS AND RESULTS: Hsp20 overexpression in intact animals resulted in significant enhancement of cardiac function, coupled with augmented Ca cycling and sarcoplasmic reticulum Ca load in isolated cardiomyocytes. This was associated with specific increases in phosphorylation of phospholamban (PLN) at both Ser16 and Thr17, relieving its inhibition of the apparent Ca affinity of SERCA2a. Accordingly, the inotropic effects of Hsp20 were abrogated in cardiomyocytes expressing nonphosphorylatable PLN (S16A/T17A). Interestingly, the activity of type 1 protein phosphatase (PP1), a known regulator of PLN signaling, was significantly reduced by Hsp20 overexpression, suggesting that the Hsp20 stimulatory effects are partially mediated through the PP1-PLN axis. This hypothesis was supported by cell fractionation, coimmunoprecipitation, and coimmunolocalization studies, which revealed an association between Hsp20, PP1, and PLN. Furthermore, recombinant protein studies confirmed a physical interaction between AA 73 to 160 in Hsp20 and AA 163 to 330 in PP1. CONCLUSIONS: Hsp20 is a novel regulator of sarcoplasmic reticulum Ca cycling by targeting the PP1-PLN axis. These findings, coupled with the well-recognized cardioprotective role of Hsp20, suggest a dual benefit of targeting Hsp20 in heart disease.
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Calcio/metabolismo , Proteínas del Choque Térmico HSP20/biosíntesis , Contracción Miocárdica , Miocardio/metabolismo , Proteína Fosfatasa 1/metabolismo , Retículo Sarcoplasmático/metabolismo , Sustitución de Aminoácidos , Animales , Proteínas de Unión al Calcio/genética , Proteínas de Unión al Calcio/metabolismo , Proteínas del Choque Térmico HSP20/genética , Cardiopatías/genética , Cardiopatías/metabolismo , Ratones , Ratones Transgénicos , Mutación Missense , Fosforilación/genética , Proteína Fosfatasa 1/genética , Retículo Sarcoplasmático/genética , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/genética , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/metabolismoRESUMEN
The Na(+)-K(+)-ATPase (NKA) can affect intracellular Ca(2+) concentration regulation via coupling to the Na(+)-Ca(2+) exchanger and may be important in myogenic tone. We previously reported that in mice carrying a transgene for the NKA alpha(2)-isoform in smooth muscle (alpha(2sm+)), the alpha(2)-isoform protein as well as the alpha(1)-isoform (not contained in the transgene) increased to similar degrees (2-7-fold). Aortas from alpha(2sm+) mice relaxed faster from a KCl-induced contraction, hypothesized to be related to more rapid Ca(2+) clearance. To elucidate the mechanisms underlying this faster relaxation, we therefore measured the expression and distribution of proteins involved in Ca(2+) clearance. Na(+)-Ca(2+) exchanger, sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA), and plasma membrane Ca(2+)-ATPase (PMCA) proteins were all elevated up to approximately fivefold, whereas actin, myosin light chain, and calponin proteins were not changed in smooth muscle from alpha(2sm+) mice. Interestingly, the corresponding Ca(2+) clearance mRNA levels were unchanged. Immunocytochemical data indicate that the Ca(2+) clearance proteins are distributed similarly in wild-type and alpha(2sm+) aorta cells. In studies measuring relaxation half-times from a KCl-induced contraction in the presence of pharmacological inhibitors of SERCA and PMCA, we estimated that together these proteins were responsible for approximately 60-70% of relaxation in aorta. Moreover, the percent contribution of SERCA and PMCA to relaxation rates in alpha(2sm+) aorta was not significantly different from that in wild-type aorta. The coordinate expressions of NKA and Ca(2+) clearance proteins without change in the relative contributions of each individual protein to smooth muscle function suggest that NKA may be but one component of a larger functional Ca(2+) clearance system.
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Calcio/metabolismo , Proteínas de Transporte de Catión/metabolismo , Músculo Liso Vascular/enzimología , Miocitos del Músculo Liso/enzimología , ATPasa Intercambiadora de Sodio-Potasio/metabolismo , Animales , Transporte Biológico , Presión Sanguínea , Proteínas de Transporte de Catión/antagonistas & inhibidores , Proteínas de Transporte de Catión/genética , Células Cultivadas , Inhibidores Enzimáticos/farmacología , Ratones , Ratones Transgénicos , Músculo Liso Vascular/efectos de los fármacos , Miocitos del Músculo Liso/efectos de los fármacos , ATPasas Transportadoras de Calcio de la Membrana Plasmática/antagonistas & inhibidores , ATPasas Transportadoras de Calcio de la Membrana Plasmática/metabolismo , ARN Mensajero/metabolismo , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/antagonistas & inhibidores , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/metabolismo , Intercambiador de Sodio-Calcio/metabolismo , ATPasa Intercambiadora de Sodio-Potasio/genética , Factores de Tiempo , Vasoconstricción , VasodilataciónRESUMEN
Contractile dysfunction and ventricular arrhythmias associated with heart failure have been attributed to aberrant sarcoplasmic reticulum (SR) Ca(2+) cycling. The study of junctin (JCN) and histidine-rich Ca(2+) binding protein (HRC) becomes of particular importance since these proteins have been shown to be critical regulators of Ca(2+) cycling. Specifically, JCN is a SR membrane protein, which is part of the SR Ca(2+) release quaternary structure that also includes the ryanodine receptor, triadin and calsequestrin. Functionally, JCN serves as a bridge between calsequestrin and the Ca(2+) release channel, ryanodine receptor. HRC is a SR luminal Ca(2+) binding protein known to associate with both triadin and the sarcoplasmic reticulum Ca(2+)-ATPase, and may thus mediate the crosstalk between SR Ca(2+) uptake and release. Indeed, evidence from genetic models of JCN and HRC indicate that they are important in cardiophysiology as alterations in these proteins affect SR Ca(2+) handling and cardiac function. In addition, downregulation of JCN and HRC may contribute to Ca(2+) cycling perturbations manifest in the failing heart, where their protein levels are significantly reduced. This review examines the roles of JCN and HRC in SR Ca(2+) cycling and their potential significance in heart failure.
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Arritmias Cardíacas/etiología , Proteínas de Unión al Calcio/fisiología , Insuficiencia Cardíaca/etiología , Proteínas de la Membrana/fisiología , Oxigenasas de Función Mixta/fisiología , Proteínas Musculares/fisiología , Animales , Arritmias Cardíacas/fisiopatología , Señalización del Calcio , Proteínas de Unión al Calcio/química , Proteínas de Unión al Calcio/deficiencia , Proteínas de Unión al Calcio/genética , Insuficiencia Cardíaca/fisiopatología , Humanos , Proteínas de la Membrana/química , Proteínas de la Membrana/deficiencia , Proteínas de la Membrana/genética , Ratones , Ratones Noqueados , Oxigenasas de Función Mixta/química , Oxigenasas de Función Mixta/deficiencia , Oxigenasas de Función Mixta/genética , Modelos Cardiovasculares , Proteínas Musculares/química , Proteínas Musculares/deficiencia , Proteínas Musculares/genética , Ratas , Retículo Sarcoplasmático/fisiologíaRESUMEN
BACKGROUND: Recent studies have identified critical roles for microRNAs (miRNAs) in a variety of cellular processes, including regulation of cardiomyocyte death. However, the signature of miRNA expression and possible roles of miRNA in the ischemic heart have been less well studied. METHODS AND RESULTS: We performed miRNA arrays to detect the expression pattern of miRNAs in murine hearts subjected to ischemia/reperfusion (I/R) in vivo and ex vivo. Surprisingly, we found that only miR-320 expression was significantly decreased in the hearts on I/R in vivo and ex vivo. This was further confirmed by TaqMan real-time polymerase chain reaction. Gain-of-function and loss-of-function approaches were employed in cultured adult rat cardiomyocytes to investigate the functional roles of miR-320. Overexpression of miR-320 enhanced cardiomyocyte death and apoptosis, whereas knockdown was cytoprotective, on simulated I/R. Furthermore, transgenic mice with cardiac-specific overexpression of miR-320 revealed an increased extent of apoptosis and infarction size in the hearts on I/R in vivo and ex vivo relative to the wild-type controls. Conversely, in vivo treatment with antagomir-320 reduced infarction size relative to the administration of mutant antagomir-320 and saline controls. Using TargetScan software and proteomic analysis, we identified heat-shock protein 20 (Hsp20), a known cardioprotective protein, as an important candidate target for miR-320. This was validated experimentally by utilizing a luciferase/GFP reporter activity assay and examining the expression of Hsp20 on miR-320 overexpression and knockdown in cardiomyocytes. CONCLUSIONS: Our data demonstrate that miR-320 is involved in the regulation of I/R-induced cardiac injury and dysfunction via antithetical regulation of Hsp20. Thus, miR-320 may constitute a new therapeutic target for ischemic heart diseases.
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Proteínas del Choque Térmico HSP20/genética , MicroARNs/fisiología , Daño por Reperfusión Miocárdica/genética , Animales , Cardiotónicos , Muerte Celular , Células Cultivadas , Perfilación de la Expresión Génica , Ratones , Ratones Transgénicos , MicroARNs/genética , Miocitos CardíacosRESUMEN
The Na(+)-K(+)-ATPase (NKA) is a transmembrane protein that sets and maintains the electrochemical gradient by extruding three Na(+) in exchange for two K(+). An important physiological role proposed for vascular smooth muscle NKA is the regulation of blood pressure via modulation of vascular smooth muscle contractility (5). To investigate the relations between the level of NKA in smooth muscle and blood pressure, we developed mice carrying a transgene for either the NKA alpha(1)- or alpha(2)-isoform (alpha(1 sm+) or alpha(2 sm+) mice) driven by the smooth muscle-specific alpha-actin promoter SMP8. Interestingly, both alpha-isoforms, the one contained in the transgene and the one not contained, were increased to a similar degree at both protein and mRNA levels. The total alpha-isoform protein was increased from 1.5-fold (alpha(1 sm+) mice) to 7-fold (alpha(2 sm+) mice). The increase in total NKA alpha-isoform protein was accompanied by a 2.5-fold increase in NKA activity in alpha(2 sm+) gastric antrum. Immunocytochemistry of the alpha(1)- and alpha(2)-isoforms in alpha(2 sm+) aortic smooth muscle cells indicated that alpha-isoform distributions were similar to those shown in wild-type cells. alpha(2 sm+) Mice (high expression) were hypotensive (109.9 +/- 1.6 vs. 121.3 +/- 1.4 mmHg; n = 13 and 11, respectively), whereas alpha(1 sm+) mice (low expression) were normotensive (122.7 +/- 2.5 vs. 117.4 +/- 2.3; n = 11 or 12). alpha(2 sm+) Aorta, but not alpha(1 sm+) aorta, relaxed faster from a KCl-induced contraction than wild-type aorta. Our results show that smooth muscle displays unique coordinate expression of the alpha-isoforms. Increasing smooth muscle NKA decreases blood pressure and is dependent on the degree of increased alpha-isoform expression.