RESUMO
Mammalian cells are surrounded by neighbouring cells and extracellular matrix (ECM), which provide cells with structural support and mechanical cues that influence diverse biological processes1. The Hippo pathway effectors YAP (also known as YAP1) and TAZ (also known as WWTR1) are regulated by mechanical cues and mediate cellular responses to ECM stiffness2,3. Here we identified the Ras-related GTPase RAP2 as a key intracellular signal transducer that relays ECM rigidity signals to control mechanosensitive cellular activities through YAP and TAZ. RAP2 is activated by low ECM stiffness, and deletion of RAP2 blocks the regulation of YAP and TAZ by stiffness signals and promotes aberrant cell growth. Mechanistically, matrix stiffness acts through phospholipase Cγ1 (PLCγ1) to influence levels of phosphatidylinositol 4,5-bisphosphate and phosphatidic acid, which activates RAP2 through PDZGEF1 and PDZGEF2 (also known as RAPGEF2 and RAPGEF6). At low stiffness, active RAP2 binds to and stimulates MAP4K4, MAP4K6, MAP4K7 and ARHGAP29, resulting in activation of LATS1 and LATS2 and inhibition of YAP and TAZ. RAP2, YAP and TAZ have pivotal roles in mechanoregulated transcription, as deletion of YAP and TAZ abolishes the ECM stiffness-responsive transcriptome. Our findings show that RAP2 is a molecular switch in mechanotransduction, thereby defining a mechanosignalling pathway from ECM stiffness to the nucleus.
Assuntos
Proteínas Serina-Treonina Quinases/metabolismo , Transdução de Sinais , Proteínas rap de Ligação ao GTP/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Transformação Celular Neoplásica , Matriz Extracelular/química , Matriz Extracelular/genética , Matriz Extracelular/metabolismo , Feminino , Proteínas Ativadoras de GTPase/metabolismo , Quinases do Centro Germinativo , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Células HEK293 , Via de Sinalização Hippo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Camundongos , Camundongos Endogâmicos NOD , Camundongos Nus , Camundongos SCID , Proteínas do Tecido Nervoso/metabolismo , Fosfolipase C gama/metabolismo , Fosfoproteínas/metabolismo , Transativadores , Fatores de Transcrição , Proteínas com Motivo de Ligação a PDZ com Coativador Transcricional , Transcriptoma , Proteínas de Sinalização YAP , Proteínas rap de Ligação ao GTP/genéticaRESUMO
OBJECTIVE: To evaluate the clinical performance and financial costs of breast-specific gamma imaging (BSGI) as a biopsy-reducing problem-solving strategy in patients with inconclusive diagnostic imaging findings. METHODS: A retrospective analysis of all patients for whom BSGI was utilized for inconclusive imaging findings following complete diagnostic mammographic and sonographic evaluation between January 2013 and December 2018 was performed. Positive BSGI findings were correlated and biopsied with either US or stereotactic technique with confirmation by clip location and pathology. After a negative BSGI result, patients were followed for a minimum of 24 months or considered lost to follow-up and excluded (22 patients). Results of further imaging studies, biopsies, and pathology results were analyzed. Net savings of avoided biopsies were calculated based on average Medicare charges. RESULTS: Four hundred and forty female patients from 30 to 95 years (mean 55 years) of age were included in our study. BSGI demonstrated a negative predictive value (NPV) of 98.4% (314/319) and a positive predictive value for biopsy of 35.5% (43/121). The overall sensitivity was 89.6% (43/48), and the specificity was 80.1% (314/392). In total, 78 false positive but only 5 false negative BSGI findings were identified. Six hundred and twenty-one inconclusive imaging findings were analyzed with BSGI and a total of 309 biopsies were avoided. Estimated net financial savings from avoided biopsies were $646 897. CONCLUSION: In the management of patients with inconclusive imaging findings on mammography or ultrasonography, BSGI is a problem-solving imaging modality with high NPV that helps avoid costs of image-guided biopsies.
RESUMO
Objective: Bedside consultation by cardiologists may facilitate safe discharge of selected patients from the emergency department (ED) even when admission is recommended by the History, Electrocardiogram, Age, Risk factors, Troponin (HEART) pathway. If bedside evaluation is unavailable, phone consultation between emergency physicians and cardiologists would be most impactful if the resultant disposition is discordant with the HEART pathway. We therefore evaluate discordance between actual disposition and that suggested by the HEART pathway in patients presenting to the ED with chest pain for whom cardiology consultation occurred exclusively by phone and to assess the impact of phone-consultation on disposition. Methods: We performed a single-center, retrospective study of adults presenting to the ED with chest pain whose emergency physician had a phone consultation with a cardiologist. Actual disposition was abstracted from the medical record. HEART pathway category (low-risk, discharge; high-risk, admit) was derived from ED documentation. For discharged patients, major adverse cardiac events were assessed at 30 days by chart review and phone follow-up. Results: For the 170 patients that had cardiologist phone consultation, discordance between actual disposition and the HEART pathway was 17%. The HEART pathway recommended admission for nearly 80% of discharged patients. Following cardiologist phone-consultation, 10% of high-risk patients were discharged, with the majority having undergone a functional study recommended by the cardiologist. At 30 days, discharged patients had experienced no episodes of major adverse cardiac events or rehospitalization for cardiac reasons. Conclusion: For patients presenting to the ED with chest pain, cardiology phone-consultation has the potential to safely impact disposition, primarily by facilitating functional testing in high-risk individuals.