Structural basis of main proteases of HCoV-229E bound to inhibitor PF-07304814 and PF-07321332.

PF-07321332 and PF-07304814, inhibitors against SARS-CoV-2 developed by Pfizer, exhibit broad-spectrum inhibitory activity against the main protease (Mpro) from various coronaviruses. Structures of PF-07321332 or PF-07304814 in complex with Mpros of various coronaviruses reveal their inhibitory mechanisms against different Mpros. However, the structural information on the lower pathogenic coronavirus Mpro with PF-07321332 or PF-07304814 is currently scarce, which hinders our comprehensive understanding of the inhibitory mechanisms of these two inhibitors. Meanwhile, given that some immunocompromised individuals are still affected by low pathogenic coronaviruses, we determined the structures of lower pathogenic coronavirus HCoV-229E Mpro with PF-07321332 and PF-07304814, respectively, and analyzed and defined in detail the structural basis for the inhibition of HCoV-229E Mpro by both inhibitors. Further, we compared the crystal structures of multiple coronavirus Mpro complexes with PF-07321332 or PF-07304814 to illustrate the differences in the interaction of Mpros, and found that the inhibition mechanism of lower pathogenic coronavirus Mpro was more similar to that of moderately pathogenic coronaviruses. Our structural studies provide new insights into drug development for low pathogenic coronavirus Mpro, and provide theoretical basis for further optimization of both inhibitors to contain potential future coronaviruses.

Cryo-EM structure of mouse TRPML2 in lipid nanodiscs.

In mammalians, transient receptor potential mucolipin ion channels (TRPMLs) exhibit variable permeability to cations such as Ca2+, Fe2+, Zn2+, and Na+ and can be activated by the phosphoinositide PI(3,5)P2 in the endolysosomal system. Loss or dysfunction of TRPMLs has been implicated in lysosomal storage disorders, infectious diseases, and metabolic diseases. TRPML2 has recently been identified as a mechanosensitive and hypotonicity-sensitive channel in endolysosomal organelles, which distinguishes it from TRPML1 and TRPML3. However, the molecular and gating mechanism of TRPML2 remains elusive. Here, we present the cryo-EM structure of the full-length mouse TRPML2 in lipid nanodiscs at 3.14 Å resolution. The TRPML2 homotetramer structure at pH 7.4 in the apo state reveals an inactive conformation and some unique features of the extracytosolic/luminal domain and voltage sensor-like domain that have implications for the ion-conducting pathway. This structure enables new comparisons between the different subgroups of TRPML channels with available structures and provides structural insights into the conservation and diversity of TRPML channels. These comparisons have broad implications for understanding a variety of molecular mechanisms of TRPMLs in different pH conditions, including with and without bound agonists and antagonists.

[Antagonistic effect of 3'-daidzein sulfonate sodium on prostatic hyperplasia in mice].

OBJECTIVE: To study the antagonistic effect of 3'-daidzein sulfonate sodium (DSS) on benign prostatic hyperplasia (BPH) and its possible mechanism. METHODS: Forty healthy mice were randomly divided into five groups: a normal control group without any treatment, a model group of BPH treated by subcutaneous injection of testosterone propionate, a positive control group with the BPH procedure treated by Qianliekang, a 20 mg/(kg x d) DSS group with the BPH procedure and a 40 mg/(kg x d) DSS group with the BPH procedure. After 12 days of the above treatments, the mice were sacrificed for measurement of the prostate glandular wet weight, the index of prostate gland (PI), the morphological changes of prostate gland by light microscopy and the contents of testosterone and estradiol in the serum. RESULTS: The prostate wet weight and PI decreased dose-dependently after DSS treatment for 12 days compared with the BPH model group (P < 0.05 or P < 0.01). The hyperplastic epithelioglandular papilla waned and even disappeared in the DSS treated groups under the light microscope, the epithelial cells became cubical or flat. The effect of DSS at 40 mg/(kg x d) was similar to that of the positive anti-BPH drug Qianliekang. DSS reduced the serum testosterone, estradiol contents and the T/E2 ratio (P < 0.05 or P < 0.01). CONCLUSION: DSS has significant antagonistic effect on BPH induced by testosterone propionate in mice, which may involve its regulatory action on the sex hormone balance.

[Constriction effect of daidzein on guinea pig's gall bladder].

OBJECTIVE: To study the effect of daidzein on gall bladder constriction. METHODS: To study daidzein how to antagonize the gall bladder constriction of guinea pig induced by acitylcholine, histamine, excessive K+ or Ca2+. RESULTS: It has been found that daidzein could remarkedly antagonize the gall bladder constriction of guinea pig induced by acitylcholine, histamine, excessive K+, cumulation Ca2+. CONCLUSION: Daidzein could obviously antagonize gall bladder constriction in guinea pig.

[Study on therapeutic window of opportunity for Panax notoginseng saponins following focal cerebral ischemia/reperfusion injury in rats].

OBJECTIVE: To study the therapeutic window of opportunity for Panax notoginseng saponins (Pns) following focal cerebral ischemia/reperfusion injury in rats. METHODS: Focal cerebral ischemia (2 h)/reperfusion (24 h) model in male rats was induced by transient occlusion and middle cerebral artery (MCA) for 2 h and reperfusion for 24 h. Drugs were administered at 3 h, 4 h, 5 h and 6 h after the onset of ischemia respectively and neurological deficit score, infarct size and brain edema were examined. RESULTS: The administration of Pns at 3-4 h after onset of ischemia significantly reduced neurological deficit score, infarct size and brain edema. When administrating Pns at 5 h after onset of ischemia, the neuroprotection decreased. When administrating Pns at 6 h after onset of ischemia, there are not significant protective effects. CONCLUSION: The therapeutic window of opportunity for Pns following focal cerebral ischemia/reperfusion injury in rats is not more than 5 h after the onset of ischemia.

[Effect of xanthnotoxol on contraction of rabbit thoracic aortic strips].

OBJECTIVE: To study the effect of xanthnotoxol (XT) on contractility of rabbit thoracic aorta strips and its relationship with Ca2+. METHODS: Routine experimental methods for isolated thoracic aorta strips were adopted. RESULTS: XT and verapamil (Ver) can make the dose-response curve of rabbit thoracic aorta strips induced by NE, KCl, CaCl2 shifed right (the pD'2 of KCl and CaCl2 value was 3.58 +/- 0.07 and 4.12 +/- 0.12) and depressed the maximal responses. Like verapamil (Ver), it is accomplished by calcium antagonism. XT could selectively block the voltage dependence calcium channel (VDC), and have no effect on the receptor operated calcium channel (ROC). CONCLUSION: It suggested XT had selectly blocking effect on voltage dependence calcium channel.

[Effect of daidzein on antiarrhythmia].

OBJECTIVE: To study the effect of Daidzein on Antiarrhythmia. METHOD: The conventional antiarrhythmia methods were used. RESULT: Daidzein was remarkedly effective in preventing ventricular fibrillation induced by chloroform in mice and arrhythmia induced by aconitine in rats. The arrhythmia induced by adrenalin in rabbits was antagonized by Daidzein and it could obviously inhibit the action potential amplitude of isolated sciatic nerves in toads. And it could also prevent ventricular fibrillation induced by calcium chloride in rats, and obviously reduce the death rate of rats. Its anti-arrhythmic effect was dose-dependent. CONCLUSION: Daidzein has obvious protective effect on drug-induced arrhythmia, which may be related to its inhibition of Na+ or Ca2+ influx and its blocking beta-adrenergic receptor.