A Disintegrin and Metalloproteinase 10 (ADAM10) is a crucial transmembrane protein involved in diverse cellular processes, including cell adhesion, migration, and proteolysis. ADAM10\'s ability to cleave over 100 substrates underscores its significance in physiological and pathological contexts, particularly in Alzheimer\'s disease (AD). This review comprehensively examines ADAM10\'s multifaceted roles, highlighting its critical function in the non-amyloidogenic processing of the amyloid precursor protein (APP), which mitigates amyloid beta (Aβ) production, a critical factor in AD development. We summarize the regulation of ADAM10 at multiple levels: transcriptional, translational, and post-translational, revealing the complexity and responsiveness of its expression to various cellular signals. A standardized nomenclature for ADAM10 isoforms is proposed to improve clarity and consistency in research, facilitating better comparison and replication of findings across studies. We address the challenges in detecting ADAM10 isoforms using antibodies, advocating for standardized detection protocols to resolve discrepancies in results from different biological matrices. This review underscores the potential of ADAM10 as a biomarker for early diagnosis and a therapeutic target in AD. By consolidating current knowledge on ADAM10\'s regulation and function, we aim to provide insights that will guide future research and therapeutic strategies in the AD context.

As they grow, sharks both replace lost denticles and proliferate the number of denticles by developing new (de novo) denticles without prior denticle shedding. The loss and replacement of denticles has potential impacts on the energetic cost of maintaining the skin surface, the biomechanical functions of shark skin, as well as our ability to predict shark abundance from fossil denticle occurrence in sediment cores. Here, we seek to better understand patterns of denticle loss and to show how denticles are being replaced in mature sharks. We illustrate shark skin surfaces with missing denticles and quantify both within-species and between-species patterns of missing denticles using images from across regions of the body for two species and images at similar body regions for 16 species of sharks. Generally, sharks are missing similar numbers of denticles (0%-6%) between species and regions. However, there are exceptions: in the smooth dogfish, the nose region is missing significantly more denticles than most posterior-body and fin regions, and the common thresher shark is missing significantly more denticles than the smooth dogfish, leopard shark, angel shark, bonnethead, and gulper shark. Denticle regrowth starts with crown development and mineralization beneath the epidermis, followed by eruption of the crown, and finally the mineralization of the root. The pulp cavity of replacement denticles is initially large and surrounded by a thin shell of enameloid upon eruption of the denticle. After eruption of the denticle, the deposition of dentine continues internally after the denticle reaches its final position. Replacement of missing denticles, representing less than 6% of the skin surface at any one time, may not compromise hydrodynamic function, but by constantly updating the skin surface throughout life, sharks may reduce surface fouling and maintain a functional complex skin surface by repairing local damage to individual denticles.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2, the virus responsible for coronavirus disease 2019, affects multiple organs. The virus enters cells through angiotensin-converting enzyme-2 and host factors present in genital organs, leading to concern over virus shedding in semen and reproductive function.
OBJECTIVE: To investigate severe acute respiratory syndrome coronavirus 2 in semen from patients with a mild infection, identify the seminal infected cells, and explore the effect of the infection on sex hormones and semen parameters.
METHODS: Prospective study of 54 men with mild severe acute respiratory syndrome coronavirus 2 infection. Semen was collected at 7, 15, 30, 60, 90, 180, and 365 days after symptom onset, and severe acute respiratory syndrome coronavirus 2 RNA was measured in serum, saliva, urine, and semen. The presence of infectious severe acute respiratory syndrome coronavirus 2 in semen was assessed using Vero cell culture. Infected semen cells were identified using immunofluorescence against severe acute respiratory syndrome coronavirus 2 nucleoprotein antigen and cell markers. Semen characteristics as well as testosterone, inhibin B, luteinizing hormone, and follicle-stimulating hormone levels were determined.
RESULTS: 11% of patients had at least one severe acute respiratory syndrome coronavirus 2 RNA-positive semen. One patient had viral semen shedding up to day 90 after infection onset, with replication-competent virus isolated from semen and 40% cell fraction at day 7. After sperm preparation, 90% fraction was severe acute respiratory syndrome coronavirus 2 RNA-positive at days 7 and 15. The swim-up fraction was positive only on day 7. In semen, nucleoprotein antigen was detected mainly in exfoliated epithelial cells and less frequently in Sertoli cells. Sperm count and motile sperm count were lower at day 30 than at day 7. Round cells in semen were increased during the acute phase. At days 7 and 15, sperm count and motile sperm count were lower in severe acute respiratory syndrome coronavirus 2 RNA-positive semen compared with negative semen, while semen volume and follicle-stimulating hormone levels were increased. Long-term follow-up shows no evidence of a detrimental effect on hormonal or semen characteristics.
CONCLUSIONS: 11% of patients with mild coronavirus disease 2019 who were not hospitalized had severe acute respiratory syndrome coronavirus 2 excretions in semen, which persisted for up to 90 days in one patient. No germ cells appeared infected by the virus, but the detection of nucleoprotein antigen-positive epithelial semen cells and Sertoli cells suggests genital tract infection. Albeit infrequent, semen may contain the replication-competent virus during the acute phase with potential risk of severe acute respiratory syndrome coronavirus 2 transmissions during sexual contact and assisted reproduction procedures. The effect of mild coronavirus disease 2019 on spermatogenesis and reproductive hormones was moderate and reversible.

UNASSIGNED: Recombinant viral-based gene therapy products, such as those incorporating adeno-associated viruses (AAVs), fall under the category of genetically modified organisms (GMOs). The European Union (EU) countries and Japan must obtain environmental risk assessment (ERA) approval for the use of GMOs before starting any clinical trials. It has been reported that the development of GMO-containing products in these two regions encounters several regulatory obstacles due to the longer regulatory procedures and document preparation for ERA.
UNASSIGNED: In this article, we comparatively analyzed the ERA document requirements in the EU and Japan for AAV-based recombinant medicinal products to highlight the differences in the context of potential future attempts of convergence. Additionally, we analyzed non-clinical and clinical shedding data requirements, which are key components of ERA reviews in the EU and Japan. Lastly, we compared the containment measures to minimize the spread of GMOs in the environment in the EU and Japan.
UNASSIGNED: Based on our comparative analysis, we present several policy recommendations of standardizing and simplifying the application materials and procedures for the ERA regulations on GMOs in the EU and Japan in the mid-, and long-term timeframe to achieve global regulatory convergence.

Considerable research has focused on microbes on amphibian skin, as they act as the first line of defense against invading pathogens. This effort has generated substantial data on patterns across species, space, time, and ontogeny, alongside a growing list of beneficial antifungal symbionts. Though there is evidence of stability in amphibian skin microbial communities, there is also an indication that regular skin shedding reduces cultivable bacteria, with regrowth and recolonization in the period between sheds. This suggests that skin communities are in constant flux, and we lack an understanding of how the membership and structure of those communities are affected by shedding events. In this study, we conducted experiments on cane toads (Rhinella marina) to investigate the influence of shedding on skin microbiomes. We first used quantitative PCR to verify a positive correlation between bacterial loads and time in the days after shedding. We then resampled individuals over time to describe changes in community composition in the 38 h after shedding using amplicon sequencing. Similar to trends of bacterial loads, we found increases in alpha diversity over time after shedding, suggesting that shedding reduces bacterial diversity as it knocks down bacterial loads. During the 38-h period, community structure became similar to pre-shed communities in some individuals, but there was no consistent pattern in structural changes among individuals. In light of the amphibian chytridiomycosis pandemic, understanding how physiological events such as skin shedding affect beneficial bacteria and communities on amphibians would provide important insight into amphibian ecology.

Phospholipase A2 receptor 1 (PLA2R1) is a 180-kDa transmembrane protein that plays a role in inflammation and cancer and is the major autoantigen in membranous nephropathy, a rare but severe autoimmune kidney disease. A soluble form of PLA2R1 has been detected in mouse and human serum. It is likely produced by proteolytic shedding of membrane-bound PLA2R1 but the mechanism is unknown. Here, we show that human PLA2R1 is cleaved by A Disintegrin And Metalloprotease 10 (ADAM10) and ADAM17 in HEK293 cells, mouse embryonic fibroblasts, and human podocytes. By combining site-directed mutagenesis and sequencing, we determined the exact cleavage site within the extracellular juxtamembrane stalk of human PLA2R1. Orthologs and paralogs of PLA2R1 are also shed. By using pharmacological inhibitors and genetic approaches with RNA interference and knock-out cellular models, we identified a major role of ADAM10 in the constitutive shedding of PLA2R1 and a dual role of ADAM10 and ADAM17 in the stimulated shedding. We did not observe evidence for cleavage by β- or γ-secretase, suggesting that PLA2R1 may not be a substrate for regulated intramembrane proteolysis. PLA2R1 shedding occurs constitutively and can be triggered by the calcium ionophore ionomycin, the protein kinase C activator PMA, cytokines, and lipopolysaccharides, in vitro and in vivo. Altogether, our results show that PLA2R1 is a novel substrate for ADAM10 and ADAM17, producing a soluble form that is increased in inflammatory conditions and likely exerts various functions in physiological and pathophysiological conditions including inflammation, cancer, and membranous nephropathy.

AbstractTemperate reptiles are often considered to be low-energy systems, with their discrete use of time and energy making them model systems for the study of time-energy budgets. However, the semifrequent replacement and sloughing of the epidermis is a ubiquitous feature of squamate reptiles that is often overlooked when accounting for time and energy budgets in these animals. We used open-flow respirometry to measure both the energetic effort of ecdysis and the duration of the associated metabolic upregulation (likely related to behavioral changes often reported for animals in shed) in wild-caught timber rattlesnakes (Crotalus horridus). We hypothesized that total effort of skin biosynthesis and physical removal would be related to body mass and expected the duration of the process to remain static across individuals at a fixed temperature (25°C). We provide both the first measurements of the cost of skin biosynthesis and physical removal in a reptile and the highest-resolution estimate of process duration recorded to date. We found that skin biosynthesis, but not the cost of physical removal of the epidermis, was related to body mass. Shed cycle duration was consistent across individuals, taking nearly 4 wk from process initiation to physical removal of the outermost epidermal layer. Total energetic effort of ecdysis was of sizeable magnitude, requiring ∼3% of the total annual energy budget of a timber rattlesnake. Energetic effort for a 500-g snake was equivalent to the amount of metabolizable energy acquired from the consumption of approximately two adult mice. Ecdysis is a significant part of the time-energy budgets of snakes, necessitating further attention in studies of reptilian energetics.

Bone resorption is driven through osteoclast differentiation by macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor kappa-Β ligand (RANKL). We noted that a disintegrin and metalloproteinase (ADAM) 10 and ADAM17 are downregulated at the expression level during osteoclast differentiation of the murine monocytic cell line RAW264.7 in response to RANKL. Both proteinases are well known to shed a variety of single-pass transmembrane molecules from the cell surface. We further showed that inhibitors of ADAM10 or ADAM17 promote osteoclastic differentiation and furthermore enhance the surface expression of receptors for RANKL and M-CSF on RAW264.7 cells. Using murine bone marrow-derived monocytic cells (BMDMCs), we demonstrated that a genetic deficiency of ADAM17 or its required regulator iRhom2 leads to increased osteoclast development in response to M-CSF and RANKL stimulation. Moreover, ADAM17-deficient osteoclast precursor cells express increased levels of the receptors for RANKL and M-CSF. Thus, ADAM17 negatively regulates osteoclast differentiation, most likely through shedding of these receptors. To assess the time-dependent contribution of ADAM10, we blocked this proteinase by adding a specific inhibitor on day 0 of BMDMC stimulation with M-CSF or on day 7 of subsequent stimulation with RANKL. Only ADAM10 inhibition beginning on day 7 increased the size of developing osteoclasts indicating that ADAM10 suppresses osteoclast differentiation at a later stage. Finally, we could confirm our findings in human peripheral blood mononuclear cells (PBMCs). Thus, downregulation of either ADAM10 or ADAM17 during osteoclast differentiation may represent a novel regulatory mechanism to enhance their differentiation process. Enhanced bone resorption is a critical issue in osteoporosis and is driven through osteoclast differentiation by specific osteogenic mediators. The present study demonstrated that the metalloproteinases ADAM17 and ADAM10 critically suppress osteoclast development. This was observed for a murine cell line, for isolated murine bone marrow cells and for human blood cells by either preferential inhibition of the proteinases or by gene knockout. As a possible mechanism, we studied the surface expression of critical receptors for osteogenic mediators on developing osteoclasts. Our findings revealed that the suppressive effects of ADAM17 and ADAM10 on osteoclastogenesis can be explained in part by the proteolytic cleavage of surface receptors by ADAM10 and ADAM17, which reduces the sensitivity of these cells to osteogenic mediators. We also observed that osteoclast differentiation was associated with the downregulation of ADAM10 and ADAM17, which reduced their suppressive effects. We therefore propose that this downregulation serves as a feedback loop for enhancing osteoclast development.

Viral vector vaccines represent a substantial advancement in immunization technology, offering numerous benefits over traditional vaccine modalities. The Orf virus (ORFV) strain D1701-VrV is a particularly promising candidate for vaccine development due to its distinctive attributes, such as a good safety profile, the ability to elicit both humoral and cellular immunity, and its favorable genetic and thermal stability. Despite ORFV\'s theoretical safety advantages, such as its narrow host range and limited systemic spread post-inoculation, a critical gap persists between these theoretical benefits and the empirical evidence regarding its in vivo safety profile. This discrepancy underscores the need for comprehensive preclinical validations to bridge this knowledge gap, especially considering ORFV\'s use in humans. Our research introduces Prime-2-CoV, an innovative ORFV-based vaccine candidate against COVID-19, designed to elicit a robust immune response by expressing SARS-CoV-2 Nucleocapsid and Spike proteins. Currently under clinical trials, Prime-2-CoV marks the inaugural application of ORFV in human subjects. Addressing the aforementioned safety concerns, our extensive preclinical evaluation, including an environmental risk assessment (ERA) and detailed pharmacokinetic studies in rats and immunocompromised NOG mice, demonstrates Prime-2-CoV\'s favorable pharmacokinetic profile, negligible environmental impact, and minimal ERA risks. These findings not only affirm the vaccine\'s safety and efficacy but also pioneer the use of ORFV-based therapeutics, highlighting its potential for wider therapeutic applications.

The suboptimal performance of rotavirus (RV) vaccines in developing countries and in animals necessitates further research on the development of novel therapeutics and control strategies. To initiate infection, RV interacts with cell-surface O-glycans, including histo-blood group antigens (HBGAs). We have previously demonstrated that certain non-pathogenic bacteria express HBGA- like substances (HBGA+) capable of binding RV particles in vitro. We hypothesized that HBGA+ bacteria can bind RV particles in the gut lumen protecting against RV species A (RVA), B (RVB), and C (RVC) infection in vivo. In this study, germ-free piglets were colonized with HBGA+ or HBGA- bacterial cocktail and infected with RVA/RVB/RVC of different genotypes. Diarrhea severity, virus shedding, immunoglobulin A (IgA) Ab titers, and cytokine levels were evaluated. Overall, colonization with HBGA+ bacteria resulted in reduced diarrhea severity and virus shedding compared to the HBGA- bacteria. Consistent with our hypothesis, the reduced severity of RV disease and infection was not associated with significant alterations in immune responses. Additionally, colonization with HBGA+ bacteria conferred beneficial effects irrespective of the piglet HBGA phenotype. These findings are the first experimental evidence that probiotic performance in vivo can be improved by including HBGA+ bacteria, providing decoy epitopes for broader/more consistent protection against diverse RVs.