RESUMEN
Alternative splicing is a potent modifier of protein function. Stromal interaction molecule 1 (Stim1) is the essential activator of store-operated Ca2+ entry (SOCE) triggering activation of transcription factors. Here, we characterize Stim1A, a splice variant with an additional 31 amino acid domain inserted in frame within its cytosolic domain. Prominent expression of exon A is found in astrocytes, heart, kidney, and testes. Full-length Stim1A functions as a dominant-negative regulator of SOCE and ICRAC, facilitating sequence-specific fast calcium-dependent inactivation and destabilizing gating of Orai channels. Downregulation or absence of native Stim1A results in increased SOCE. Despite reducing SOCE, Stim1A leads to increased NFAT translocation. Differential proteomics revealed an interference of Stim1A with the cAMP-SOCE crosstalk by altered modulation of phosphodiesterase 8 (PDE8), resulting in reduced cAMP degradation and increased PIP5K activity, facilitating NFAT activation. Our study uncovers a hitherto unknown mechanism regulating NFAT activation and indicates that cell-type-specific splicing of Stim1 is a potent means to regulate the NFAT signalosome and cAMP-SOCE crosstalk.
Asunto(s)
Canales de Calcio , Calcio , Calcio/metabolismo , Canales de Calcio/genética , Canales de Calcio/metabolismo , Señalización del Calcio/fisiología , Proteína ORAI1/metabolismo , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Molécula de Interacción Estromal 1/química , Molécula de Interacción Estromal 1/genética , Molécula de Interacción Estromal 1/metabolismoRESUMEN
INTRODUCTION: The management of periprosthetic joint infections (PJI) of the lower limb is challenging, and evidence-based recommendations are lacking. The present clinical investigation characterized the pathogens diagnosed in patients who underwent revision surgery for PJI of total hip arthroplasty (THA) and total knee arthroplasty (TKA). METHODS: The present study follows the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE). The institutional databases of the RWTH University Medical Centre of Aachen, Germany, were accessed. The OPS (operation and procedure codes) 5-823 and 5-821 and the ICD (International Statistical Classification of Diseases and Related Health Problems) codes T84.5, T84.7 or T84.8 were used. All patients with PJI of a previous THA and TKA who underwent revision surgery were retrieved and included for analysis. RESULTS: Data from 346 patients were collected (181 THAs and 165 TKAs). 44% (152 of 346 patients) were women. Overall, the mean age at operation was 67.8 years, and the mean BMI was 29.2 kg/m2. The mean hospitalization length was 23.5 days. 38% (132 of 346) of patients presented a recurrent infection. CONCLUSION: PJI remain a frequent cause for revisions after total hip and knee arthroplasty. Preoperative synovial fluid aspiration was positive in 37%, intraoperative microbiology was positive in 85%, and bacteraemia was present in 17% of patients. Septic shock was the major cause of in-hospital mortality. The most common cultured pathogens were Staph. epidermidis, Staph. aureus, Enterococcus faecalis, and Methicillin-resistant Staph aureus (MRSA). An improved understanding of PJI pathogens is important to plan treatment strategies and guide the choice of empirical antibiotic regimens in patients presenting with septic THAs and TKAs. LEVEL OF EVIDENCE: Level III, retrospective cohort study.
Asunto(s)
Artritis Infecciosa , Artroplastia de Reemplazo de Cadera , Infecciones Relacionadas con Prótesis , Humanos , Femenino , Masculino , Infecciones Relacionadas con Prótesis/cirugía , Infecciones Relacionadas con Prótesis/microbiología , Reoperación , Estudios Retrospectivos , Mortalidad Hospitalaria , Artroplastia de Reemplazo de Cadera/efectos adversos , Extremidad Inferior/cirugíaRESUMEN
BACKGROUND: True uterine artery aneurysms, especially during pregnancy, are a rare entity and not well understood. Clinical symptoms are unspecific pelvic pain and pressure. Diagnosis can be confirmed by transvaginal color-coded-sonography and/or magnetic resonance imaging. Because of potential risk of rupture, immediate interdisciplinary discussion and treatment planning in the best interests of both mother and child is crucial. CASE PRESENTATION: We present a 31-year-old pregnant woman with increasing pelvic pain and pressure. Diagnosis of an unruptured uterine artery aneurysm was confirmed by color-coded-sonography and magnetic resonance angiography. After interdisciplinary consultation, successful endovascular super-selective coil-embolization was performed by using X-ray fluoroscopy. Thus, fetal radiation dose during treatment with 4.33 mGy (VirtualDoseTM) was as low as possible with no immediate harm to the fetus. CONCLUSIONS: Unruptured true uterine artery aneurysms can be successfully treated by endovascular super-selective coil-embolization during early pregnancy with no immediate harm to the fetus.
RESUMEN
Store-operated Ca2+-entry (SOCE) regulates basal and receptor-triggered Ca2+ signaling with STIM proteins sensing the endoplasmic reticulum (ER) Ca2+ content and triggering Ca2+ entry by gating Orai channels. Although crucial for immune cells, STIM1's role in neuronal Ca2+ homeostasis is controversial. Here, we characterize a splice variant, STIM1B, which shows exclusive neuronal expression and protein content surpassing conventional STIM1 in cerebellum and of significant abundance in other brain regions. STIM1B expression results in a truncated protein with slower kinetics of ER-plasma membrane (PM) cluster formation and ICRAC, as well as reduced inactivation. In primary wild-type neurons, STIM1B is targeted by its spliced-in domain B to presynaptic sites where it converts classic synaptic depression into Ca2+- and Orai-dependent short-term synaptic enhancement (STE) at high-frequency stimulation (HFS). In conjunction with altered STIM1 splicing in human Alzheimer disease, our findings highlight STIM1 splicing as an important regulator of neuronal calcium homeostasis and of synaptic plasticity.
Asunto(s)
Molécula de Interacción Estromal 1/metabolismo , Sinapsis/metabolismo , Animales , Membrana Celular/metabolismo , Retículo Endoplásmico/metabolismo , Exones/genética , Células HEK293 , Humanos , Ratones Endogámicos C57BL , Neuronas/metabolismo , Proteína ORAI1/metabolismo , Fenotipo , Terminales Presinápticos/metabolismo , Dominios Proteicos , Isoformas de Proteínas/química , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Empalme del ARN/genética , Transducción de Señal , Molécula de Interacción Estromal 1/química , Molécula de Interacción Estromal 1/genéticaRESUMEN
Adjusting intracellular calcium signaling is an important feature in the regulation of immune cell function and survival. Here we show that miR-34a-5p, a small non-coding RNA that is deregulated in many common diseases, is a regulator of store-operated Ca2+ entry (SOCE) and calcineurin signaling. Upon miR-34a-5p overexpression, we observed both a decreased depletion of ER calcium content and a decreased Ca2+ influx through Ca2+ release-activated Ca2+ channels. Based on an in silico target prediction we identified multiple miR-34a-5p target genes within both pathways that are implicated in the balance between T-cell activation and apoptosis including ITPR2, CAMLG, STIM1, ORAI3, RCAN1, PPP3R1, and NFATC4. Functional analysis revealed a decrease in Ca2+ activated calcineurin pathway activity measured by a reduced IL-2 secretion due to miR-34a-5p overexpression. Impacting SOCE and/or downstream calcineurin/NFAT signaling by miR-34a-5p offers a possible future approach to manipulate immune cells for clinical interventions.