PTP-MEG2 regulates quantal size and fusion pore opening through two distinct structural bases and substrates.

Tyrosine phosphorylation of secretion machinery proteins is a crucial regulatory mechanism for exocytosis. However, the participation of protein tyrosine phosphatases (PTPs) in different exocytosis stages has not been defined. Here we demonstrate that PTP-MEG2 controls multiple steps of catecholamine secretion. Biochemical and crystallographic analyses reveal key residues that govern the interaction between PTP-MEG2 and its substrate, a peptide containing the phosphorylated NSF-pY83 site, specify PTP-MEG2 substrate selectivity, and modulate the fusion of catecholamine-containing vesicles. Unexpectedly, delineation of PTP-MEG2 mutants along with the NSF binding interface reveals that PTP-MEG2 controls the fusion pore opening through NSF independent mechanisms. Utilizing bioinformatics search and biochemical and electrochemical screening approaches, we uncover that PTP-MEG2 regulates the opening and extension of the fusion pore by dephosphorylating the DYNAMIN2-pY125 and MUNC18-1-pY145 sites. Further structural and biochemical analyses confirmed the interaction of PTP-MEG2 with MUNC18-1-pY145 or DYNAMIN2-pY125 through a distinct structural basis compared with that of the NSF-pY83 site. Our studies thus provide mechanistic insights in complex exocytosis processes.

Management protocol for emergency aneurysm craniotomy clipping in non-major COVID-19 epidemic areas in Beijing, China.

BACKGROUND: An epidemic of COVID-19 broke out in Wuhan, China, since December 2019. The ordinary medical services were hindered. However, the emergency cases, including aneurysmal subarachnoid hemorrhage (aSAH), still required timely intervention. Thus, it provoked challenges to the routine management protocol. In this study, we summarized our experience in the emergency management of aSAH (Beijing Tiantan Protocol, BTP) in Beijing, China. METHODS: Demographic, clinical, and imaging data of consecutive emergency aSAH patients who underwent craniotomy clipping during the COVID-19 epidemic season were reviewed and compared with the retrospective period last year. Subgroup analysis was further performed to assess the outcomes of different screening results and several detailed protocols. Neurological outcomes were evaluated by the modified Rankin Scale (mRS). RESULTS: A total of 127 aSAH were referred to our emergency department, and 42 (33.1%) underwent craniotomy clipping between January 20, 2020, and March 25, 2020. The incidence of preoperative hospitalized adverse events and the perioperative outcomes were similar (- 0.1, 95% CI - 1.0 to 0.8, P = 0.779) to the retrospective period last year (January 2019-March 2019). After the propensity score matching (PSM), there were still no statistical differences in prognostic parameters between the two groups. Eight (19.0%) of the 42 individuals were initially screened as preliminary undetermined COVID-19 cases, in which 2 of them underwent craniotomy clipping in the negative pressure operating room (OR). The prognosis of patients with varied COVID-19 screening results was similar (F(2, 39) = 0.393, P = 0.678). Since February 28, 12 cases (28.6%) received COVID-19 nucleic acid testing (NAT) upon admission, and all showed negative. The false-negative rate was 0.0%. The preoperative hospitalized adverse events and postoperative prognosis were still similar between patients with and without COVID-19 NAT (- 0.3, 95% CI - 1.4 to 0.9, P = 0.653). CONCLUSIONS: Our emergency surgery management protocol (BTP) is reliable for scheduling emergency aneurysm craniotomy clipping in non-major epidemic areas.