Biology subjects

Sun, M.-X.

Publications and source records attributed to Sun, M.-X..

4 recordsLinked to original sources

bioRxiv2024

Identification of a Conserved B-Cell Epitope on the Capsid Protein of Porcine Circovirus Type 4

Porcine circovirus type 4 (PCV4), a recently identified circovirus, is prevalent in numerous provinces in China, as well as in South Korea, Thailand, and Europe. PCV4 virus rescued from an infectious clone showed pathogenicity, suggesting the economic impact of PCV4. However, there remains a lack of understanding regarding the immunogenicity and epitopes of PCV4. This study generated a monoclonal antibody (MAb) 1D8 by immunizing mice with PCV4 virus-like particles (VLPs). Subsequently, the epitope recognized by the MAb 1D8 was identified by truncated protein expression and alanine scanning mutagenesis analysis. Results showed that the 225PKQG228 located at the C-terminus of the PCV4 Cap protein is the minimal motif binding to the MAb. Homology modeling analysis and immunoelectron microscopy revealed that the epitope extends beyond the outer surface of the PCV4 VLP. Moreover, the epitope is highly conserved among PCV4 strains and does not react with other PCVs. Together, the MAb 1D8 recognized epitope shows potential for detecting PCV4. These findings significantly contribute to the design of antigens for PCV4 detection and control strategies. IMPORTANCEPorcine circovirus type 4 (PCV4) is a novel circovirus. Although PCV4 has been identified in several countries, including China, Korea, Thailand, and Spain, no vaccine is available. Given the potential pathogenic effects of PCV4 on pigs, PCV4 could threaten the global pig farming industry, highlighting the urgency for further investigation. Thus, epitopes of PCV4 remain to be determined. Our finding of a conserved epitope significantly advances vaccine development and pathogen detection.

microbiology↗

bioRxiv2023

Atlas of Fshr Expression from Novel Reporter Mice

The FSH-FSHR signaling pathway has traditionally been considered an essential regulator in reproductive development and fertility. But there has been emerging evidence of FSHR expression in extragonadal tissues/organs. This poses new questions and long-term debates regarding the physiological role of the FSH-FSHR pathway, and underscores the need for reliable, in vivo analysis of FSHR expression in animal models. However, conventional methods have proven insufficient for examining FSHR expression due to limitations, such as the scarcity of reliable antibodies, rapid turnover/degradation of transcripts, and a lack of robust in vivo tools. To address this challenge, we developed Fshr-ZsGreen knockin reporter mice under the control of Fshr endogenous promoter using CRISPR/Cas9 genome-editing technology to append a P2A-ZsGreen targeting vector into a locus between the last exon and the stop codon of Fshr. With this novel genetic tool, we provide a reliable readout of Fshr expression at single-cell resolution level in vivo and in real time. Reporter animals were also subjected to additional analyses, including immunohistochemical staining, ddRT-PCR, and in situ hybridization, to define the accurate expression profile of FSHR in gonadal and extragonadal organs/tissues. Our compelling results not only demonstrated Fshr expression in intragonadal tissues but also, strikingly, unveiled notably increased expression in Leydig cells, osteoblast lineage cells, endothelial cells in vascular structures, and epithelial cells in bronchi of the lung and renal tubes. The genetic decoding of the widespread pattern of Fshr expression highlights its physiological relevance beyond reproduction and fertility, and opens new avenues for therapeutic options for age-related disorders of the bones, lungs, kidneys, and hearts, among other tissues/organs. Exploiting the power of the Fshr knockin reporter animals, this report provides the first comprehensive genetic record of the spatial distribution of FSHR expression, correcting a long-term misconception about Fshr expression and offering prospects for extensive exploration of FSH-FSHR biology.

cell biology↗

bioRxiv2020

Endosperm development is an autonomously programmed process independent of embryogenesis

The seeds of land plants contain three genetically distinct structures: the embryo, endosperm, and seed coat. The embryo and endosperm need to interact and exchange signals to ensure coordinated growth. Accumulating evidence has confirmed that embryo growth is supported by the nourishing endosperm and regulated by signals originating from the endosperm. Available data also support that endosperm development requires communication with the embryo. Here, using single-fertilization mutants, Arabidopsis dmp8/9 and gex2, we demonstrate that in the absence of a zygote and embryo, endosperm initiation, syncytium formation, free nuclear cellularization, and endosperm degeneration are as normal as in the wild type in terms of the cytological process and time course. Although rapid embryo expansion accelerates endosperm breakdown, our findings strongly suggest that endosperm development is an autonomously organized process, independent of egg cell fertilization and embryo-endosperm communication. This work confirms both the altruistic and self-directed nature of the endosperm during coordinated embryo-endosperm development. The findings provide novel insights into the intricate interaction between the two fertilization products and will help to distinguish the real roles of the signaling between endosperm and embryo. These finding also shed new light on agro-biotechnology for crop improvement.

plant biology↗

bioRxiv2020

Cell entry of SARS-CoV-2 conferred by angiotensin-converting enzyme 2 (ACE2) of different species

The outbreak of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a huge threat to many countries around the world. However, where is it origin and which animals are sensitive to cross-species transmission is unclear. The interaction of virus and cell receptor is a key determinant of host range for the novel coronavirus. Angiotensin-converting enzyme 2 (ACE2) is demonstrated as the primary entry receptor for SARS-CoV-2. In this study, we evaluated the SARS-CoV-2 entry mediated by ACE2 of 11 different species of animals, and discovered that ACE2 of Rhinolophus sinicus (Chinese horseshoe bat), Felis catus (domestic cat), Canis lupus familiaris (dog), Sus scrofa (pig), Capra hircus (goat) and especially Manis javanica (Malayan pangolin) were able to render SARS-CoV-2 entry in non-susceptible cells. This is the first report that ACE2 of Pangolin could mediate SARS-CoV-2 entry which increases the presume that SARS-CoV-2 may have a pangolin origin. However, none of the ACE2 proteins from Rhinolophus ferrumequinum (greater horseshoe bat), Gallus gallus (chicken), Notechis scutatus (mainland tiger snake), Mus musculus (house mouse) rendered SARS-CoV-2 entry. Specifically, a natural isoform of Macaca mulatta (Rhesus monkey) ACE2 with a mutation of Y217N was resistance to infection, which rises the possible impact of this type of ACE2 during monkey studies of SARS-CoV-2. Overall, these results clarify that SARS-CoV-2 could engage receptors of multiple species of animals and it is a perplexed work to track SARS-CoV-2 origin and its intermediate hosts. IMPORTANCEIn this study, we illustrated that SARS-CoV-2 is able to engage receptors of multiple species of animals. This indicated that it may be a perplexed work to track SARS-CoV-2 origin and discover its intermediate hosts. This feature of virus is considered to potentiate its diverse cross-species transmissibility. Of note, here is the first report that ACE2 of Pangolin could mediate SARS-CoV-2 entry which increases the possibility that SARS-CoV-2 may have a pangolin origin. And we also demonstrated that not all species of bat were sensitive to SARS-CoV-2 infection. At last, it is also important to detect the expression ratio of the Y217N ACE2 to the prototype in Rhesus monkeys to be recruited for studies on SARS-CoV-2 infection.

microbiology↗