A tissue specific-infection mouse model of SARS-CoV-2.

Animal models play crucial roles in the rapid development of vaccines/drugs for the prevention and therapy of COVID-19, but current models have some deficits when studying the pathogenesis of SARS-CoV-2 on some special tissues or organs. Here, we generated a human ACE2 and SARS-CoV-2 NF/F knockin mouse line that constitutively expresses human ACE2 and specifically expresses SARS-CoV-2 N gene induced by Cre-recombinase. By crossing with Cre transgenic lines allowing for lung-specific and constitutive expression, we generated lung-specific (Sftpc-hACE2-NF/F) and constitutive SARS-CoV-2 N (EIIa-hACE2-NF/F) expressing mice. Upon intranasal infection with a SARS-CoV-2 GFP/ΔN strain which can only replicate in SARS-CoV-2 N expressed cells, we demonstrated that both the Sftpc-hACE2-NF/F and EIIa-hACE2-NF/F mice support viral replication. Consistent with our design, viral replication was limited to the lung tissues in Sftpc-hACE2-NF/F mice, while the EIIa-hACE2-NF/F mice developed infections in multiple tissues. Furthermore, our model supports different SARS-CoV-2 variants infection, and it can be successfully used to evaluate the effects of therapeutic monoclonal antibodies (Ab1F11) and antiviral drugs (Molnupiravir). Finally, to test the effect of SARS-CoV-2 infection on male reproduction, we generated Sertoli cell-specific SARS-CoV-2 N expressed mice by crossing with AMH-Cre transgenic line. We found that SARS-CoV-2 GFP/ΔN strain could infect Sertoli cells, led to spermatogenic defects due to the destruction of blood-testis barrier. Overall, combining with different tissue-specific Cre transgenic lines, the human ACE2 and SARS-CoV-2 NF/F line enables us to evaluate antivirals in vivo and study the pathogenesis of SARS-CoV-2 on some special tissues or organs.

CCDC176 stabilizes microtubule doublets 1 and 9 to ensure proper sperm movement.

The molecular mechanism underlying asymmetric axonemal complexes in sperm flagella is still largely unknown. Here, we showed that the knockout of the coiled-coil domain-containing 176 (CCDC176) in mice led to male infertility due to decreased sperm motility. Ccdc176 knockout specifically destabilized microtubule doublets (MTDs) 1 and 9 during sperm maturation in the corpus epididymis. Single-sperm immunofluorescence showed that most CCDC176 was distributed along the axoneme, and further super-resolution imaging revealed that CCDC176 is asymmetrically localized in the sperm axoneme. CCDC176 could cooperate with microtubule and radial spoke proteins to stabilize MTDs 1 and 9, and its knockout results in the destabilization of some proteins in sperm flagella. Furthermore, as predicted by the sperm multibody dynamics (MBD) model, we found that MTDs 1 and 9 jutted out from the sperm flagellum annulus region in Ccdc176-/- spermatozoa, and these flagellar defects alter sperm flagellar beat patterns and swimming paths, potentially owing to the reduction and disequilibration of bending torque on the central pair. These results demonstrate that CCDC176 specifically stabilizes MTDs 1 and 9 in the sperm flagellum to ensure proper sperm movement for fertilization.

miR-542-3p reduces antioxidant capacity in goat caput epididymal epithelial cells by targeting glutathione peroxidase 5 (GPx5).

The mammalian epididymis provides an optimal and antioxidative fluid microenvironment for post-testicular sperm maturation by secretion of antioxidant scavengers and removal of excessive ROS. MicroRNAs (miRNAs) are expressed in the epididymis and involved in the regulation of epididymis physiology and functions. However, whether miRNAs are involved in regulating the antioxidant capacity and oxidative damage in the epididymis is not well understood. This study was designed to investigate the role of miR-542-3p in the regulation of antioxidant capacity and oxidative damage in the epididymis of goats. Firstly, we determined the expression of miR-542-3p and glutathione peroxidase 5 (GPx5) in the epididymis of young and adult goats using RT-qPCR assay, and found that miR-542-3p and GPx5 exhibited inverse expression levels. Our results showed that the expression level of miR-542-3p in epididymis was upregulated (P < 0.05) in young goats compared to adult goats, whereas the expression level of GPx5 in epididymis was downregulated (P < 0.01) in young goats compared to adult goats. Next, we further investigated the roles and potential mechanisms of miR-542-3p in epididymis using goat caput epididymal epithelial cells (GCEECs) isolated from Tai-hang goats (9-month-old). Our results showed that the overexpression of miR-542-3p in GCEECs transfected with miR-542-3p mimics resulted in decreased (P < 0.05) antioxidant enzyme activities of superoxide dismutase (SOD) and catalase (CAT). Similarly, the overexpression of miR-542-3p in GCEECs resulted in decreased (P < 0.05) glutathione (GSH) content and total antioxidant capacity (TAOC). In addition, the overexpression of miR-542-3p in GCEECs resulted in increased (P < 0.05) malonaldehyde (MDA) content. The inverse results of SOD, CAT, GSH, TAOC and MDA were observed in the down-expression of miR-542-3p in GCEECs transfected with miR-542-3p inhibitors (P < 0.05). Furthermore, GPx5 was confirmed to be a validated target of miR-542-3p in GCEECs using a dual-luciferase reporter assay, and transfection of miR-542-3p mimics decreased (P < 0.05) the mRNA expression and protein level of GPx5. In conclusion, our results indicated that miR-542-3p reduced antioxidant capacity and increased oxidative damage in GCEECs by targeting GPx5. The present study further understands the regulation of antioxidant capacity and epididymal-specific GPx5 secretion in caput epididymidis.