Receptor-stimulated generation of intracellular reactive oxygen species (ROS) modulates signal transduction, although the mechanism(s) is unclear. One potential basis is the reversible oxidation of the active site cysteine of protein tyrosine phosphatases (PTPs). Here, we show that activation of the antigen receptor of T cells (TCR), which induces production of ROS, induces transient inactivation of the SH2 domain-containing PTP, SHP-2, but not the homologous SHP-1. SHP-2 is recruited to the LATGads-SLP-76 complex and directly regulates the phosphorylation of key signaling proteins Vav1 and ADAP. Furthermore, the association of ADAP with the adapter SLP-76 is regulated by SHP-2 in a redox-dependent manner. The data indicate that TCR-mediated ROS generation leads to SHP-2 oxidation, which promotes T-cell adhesion through effects on an SLP-76-dependent signaling pathway to integrin activation.

Coronavirus disease 2019 (COVID-19) is a newly emerging human infectious disease caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2, also previously known as 2019-nCoV). Within 8 months of the outbreak, more than 10,000,000 cases of COVID-19 have been confirmed worldwide. Since human-to-human transmission occurs easily and the rate of human infection is rapidly increasing, sensitive and early diagnosis is essential to prevent a global outbreak. Recently, the World Health Organization (WHO) announced various primer–probe sets for SARS-CoV-2 developed at different institutions: China Center for Disease Control and Prevention (China CDC, China), Charité (Germany), The University of Hong Kong (HKU, Hong Kong), National Institute of Infectious Diseases in Japan (Japan NIID, Japan), National Institute of Health in Thailand (Thailand NIH, Thailand), and US CDC (USA). In this study, we compared the ability to detect SARS-CoV-2 RNA among seven primer–probe sets for the N gene and three primer–probe sets for the Orf1 gene. The results revealed that “NIID_2019-nCOV_N” from the Japan NIID and “ORF1ab” from China CDC represent a recommendable performance of RT-qPCR analysis for SARS-CoV-2 molecular diagnostics without nonspecific amplification and cross-reactivity for hCoV-229E, hCoV-OC43, and MERS-CoV RNA. Therefore, the appropriate combination of NIID_2019-nCOV_N (Japan NIID) and ORF1ab (China CDC) sets should be selected for sensitive and reliable SARS-CoV-2 molecular diagnostics.

Serine protease inhibitors (serpins) are metastable in their native state. This strain, which is released upon binding to target proteases, is essential for the inhibitory activity of serpins. To understand the structural basis of the native strain, we previously characterized stabilizing mutations of ␣ 1 -antitrypsin, a prototypical inhibitory serpin, in regions such as the hydrophobic core. The present study evaluates the effects of single point mutations throughout the molecule on stability and protease inhibitory activity. We identified stabilizing mutations in most secondary structures, suggesting that the native strain is distributed throughout the molecule. Examination of the substitution patterns and the structures of the mutation sites revealed surface hydrophobic pockets as a component of the native strain in ␣ 1 -antitrypsin, in addition to the previously identified unusual interactions such as side chain overpacking and cavities. Interestingly, many of the stabilizing substitutions did not affect the inhibitory activity significantly. Those that affected the activity were confined in the regions that are mobilized during the complex formation with a target enzyme. The results of our study should be useful for designing proteins with strain and for regulating the stability and functions of serpins.1 is a prototype of the serpin (serine protease inhibitor) superfamily that shares a common tertiary structure composed of three ␤-sheets and several ␣-helices (1). Serpins include protease inhibitors in blood plasma such as ␣ 1 AT, ␣ 1 -antichymotrypsin, antithrombin III, plasminogen activator inhibitor-I, C1 inhibitor, and ␣ 2 -antiplasmin, as well as non-inhibitory members such as ovalbumin and angiotensinogen (1, 2). One salient feature of the inhibitory serpin structure is the strain in the native conformation (3-7), which is necessary for biological functions such as protease inhibition and ligand binding (1,2,8,9). The inhibition process of serpins can be described as a suicide substrate mechanism (10 -12) in which serpins, upon binding proteases, partition between cleaved serpins and stable serpin-enzyme complexes. The stoichiometry of inhibition (SI; the number of moles of inhibitor required to completely inhibit 1 mol of a target protease) is designated as 1 ϩ k substrate /k inhibition , in which k substrate is the rate constant for the substrate pathway toward the cleaved serpin and k inhibition is the rate constant for the inhibitory pathway toward the complex formation. For cognate target proteases, most serpin molecules partition into the complex formation, bringing the SI values close to 1. During the complex formation, the reactive center loop (RCL) of inhibitory serpins is cleaved (13-15) and inserted into the major ␤-sheet, A sheet, forming a stable complex between the serpin and the protease (11,12,(15)(16)(17). It has been suggested that the rate of loop insertion is critical for inhibitory function; retardation of the loop insertion would alter the partitioning between the inhibitory and...