RESUMO
Transglutaminases (denoted TG or TGM) are externalized from cells via an unknown unconventional secretory pathway. Here, we show for the first time that purinergic signaling regulates active secretion of TG2 (also known as TGM2), an enzyme with a pivotal role in stabilizing extracellular matrices and modulating cell-matrix interactions in tissue repair. Extracellular ATP promotes TG2 secretion by macrophages, and this can be blocked by a selective antagonist against the purinergic receptor P2X7 (P2X7R, also known as P2RX7). Introduction of functional P2X7R into HEK293 cells is sufficient to confer rapid, regulated TG2 export. By employing pharmacological agents, TG2 release could be separated from P2X7R-mediated microvesicle shedding. Neither Ca(2+) signaling alone nor membrane depolarization triggered TG2 secretion, which occurred only upon receptor membrane pore formation and without pannexin channel involvement. A gain-of-function mutation in P2X7R associated with autoimmune disease caused enhanced TG2 externalization from cells, and this correlated with increased pore activity. These results provide a mechanistic explanation for a link between active TG2 secretion and inflammatory responses, and aberrant enhanced TG2 activity in certain autoimmune conditions.
Assuntos
Trifosfato de Adenosina/metabolismo , Sinalização do Cálcio , Proteínas de Ligação ao GTP/metabolismo , Potenciais da Membrana , Receptores Purinérgicos P2X7/metabolismo , Transglutaminases/metabolismo , Doenças Autoimunes/genética , Doenças Autoimunes/metabolismo , Linhagem Celular Tumoral , Feminino , Proteínas de Ligação ao GTP/genética , Células HEK293 , Humanos , Masculino , Mutação , Proteína 2 Glutamina gama-Glutamiltransferase , Receptores Purinérgicos P2X7/genética , Transglutaminases/genéticaRESUMO
BACKGROUND: Stratifying patient populations by risk of adverse events was believed to support preventive care for those identified, but recent evidence does not support this. Emergency admission risk stratification (EARS) tools have been widely promoted in UK policy and GP contracts. AIM: To describe availability and use of EARS tools across the UK, and identify factors perceived to influence implementation. DESIGN AND SETTING: Cross-sectional survey in UK. METHOD: Online survey of 235 organisations responsible for UK primary care: 209 clinical commissioning groups (CCGs) in England; 14 health boards in Scotland; seven health boards in Wales; and five local commissioning groups (LCGs) in Northern Ireland. Analysis results are presented using descriptive statistics for closed questions and by theme for open questions. RESULTS: Responses were analysed from 171 (72.8%) organisations, of which 148 (86.5%) reported that risk tools were available in their areas. Organisations identified 39 different EARS tools in use. Promotion by NHS commissioners, involvement of clinical leaders, and engagement of practice managers were identified as the most important factors in encouraging use of tools by general practices. High staff workloads and information governance were identified as important barriers. Tools were most frequently used to identify individual patients, but also for service planning. Nearly 40% of areas using EARS tools reported introducing or realigning services as a result, but relatively few reported use for service evaluation. CONCLUSION: EARS tools are widely available across the UK, although there is variation by region. There remains a need to align policy and practice with research evidence.