Biology subjects

Zhang, R. M.

Publications and source records attributed to Zhang, R. M..

5 recordsLinked to original sources

bioRxiv2024

ABA increases fatty acids levels in apple roots to boost colonization by arbuscular mycorrhizal fungi

The roots of most land plants are in symbiosis with arbuscular mycorrhizal (AM) fungi. The fungus promotes nutrient uptake from the soil while receiving plant photosynthate as lipids and sugars. Nutrient exchange must be regulated by both partners, but the mechanisms underlying the regulation of lipid supplement from the plant to the AM fungus remain elusive. Here, we conducted a molecular study on the role of increased abscisic acid (ABA) levels during AM fungus infection in the roots of apple (Malus spp.). AM fungus induced the expression of two ABA synthesis genes, MdNCED3.1 and 3.2, in apple roots and increased the ABA content, which promoted the growth of the AM fungus. The effect of ABA on symbiosis was confirmed in transgenic apple roots either overexpressing or silencing MdNCED3.1 or MdNCED3.2. Transcriptome analysis and transgenic manipulation revealed that the transcription factor MdABF2 played a key role in the ABA-mediated formation of symbiosis during AM infection and that MdABF2 could regulate the expression levels of genes related to fatty acid (FA) synthesis (e.g., MdKASIII) and translocation (such as MdSTR2) in apple roots. Activation of these genes boosted the levels of available fatty acids in the roots and increased the AM fungal colonization and arbuscule development in the roots. These results revealed a molecular pathway in which positive regulation of FA synthesis and transport by the ABA signaling pathway increases supplementation to AM fungi and promotes AM symbiosis.

molecular biology↗

bioRxiv2023

Antigenicity and receptor affinity of SARS-CoV-2 BA.2.86 spike

Although the COVID-19 pandemic has officially ended1, SARS-CoV-2 continues to spread and evolve. Recent infections have been dominated by XBB.1.5 and EG.5.1 subvariants2. A new subvariant designated BA.2.86 has just emerged, spreading to 21 countries in 5 continents3. This virus contains 34 spike mutations compared to its BA.2 predecessor, thereby raising concerns about its propensity to evade existing antibodies. We examined its antigenicity using human sera and monoclonal antibodies (mAbs). Reassuringly, BA.2.86 was not more resistant to human sera than XBB.1.5 and EG.5.1, indicating that the new subvariant would not have a growth advantage in this regard. Importantly, sera from patients who had XBB breakthrough infection exhibited robust neutralizing activity against all viruses tested, suggesting that upcoming XBB.1.5 monovalent vaccines could confer added protection. The finding that the longer genetic distance of BA.2.86 did not yield a larger antigenic distance was partially explained by the mAb data. While BA.2.86 showed greater resistance to mAbs to subdomain 1 (SD1) and receptor-binding domain (RBD) class 2 and 3 epitopes, it was more sensitive to mAbs to class 1 and 4/1 epitopes in the "inner face" of RBD that is exposed only when this domain is in the "up" position. We also identified six new spike mutations that mediate antibody resistance, including E554K that threatens SD1 mAbs in clinical development. The BA.2.86 spike also had a remarkably high receptor affinity. The ultimate trajectory of this new SARS-CoV-2 variant will soon be revealed by continuing surveillance, but its worldwide spread is worrisome.

microbiology↗

bioRxiv2023

Antibody Neutralization of Emerging SARS-CoV-2: EG.5.1 and XBC.1.6

SARS-CoV-2 variants EG.5.1 and XBC.1.6 have recently emerged, attracting increased attention due to their rapid expansion globally and in Australia, respectively. EG.5.1 evolved from Omicron subvariant XBB.1.9, harboring additional Q52H and F456L spike substitutions. The F456L mutation is located within the epitopes of many class-1 monoclonal antibodies (mAbs) directed to the receptor-binding domain (RBD), raising concerns about further antibody evasion. XBC.1.6, a descendant of a Delta-BA.2 recombinant, carries 15 additional spike mutations. The extent to which antibody evasion contributes to the growth advantage of XBC.1.6 in Australia remains to be determined. To assess the antibody evasion properties of the emergent variants, we conducted pseudovirus neutralization assays using sera from individuals who received three doses of COVID-19 mRNA monovalent vaccines plus one dose of a BA.5 bivalent vaccine, as well as from patients with BQ or XBB breakthrough infection. The assays were also performed using a panel of 14 mAbs that retained neutralizing activity against prior XBB subvariants. Our data suggested that EG.5.1 was slightly but significantly more resistant (< 2-fold) to neutralization by BQ and XBB breakthrough sera than XBB.1.16, which is known to be antigenically similar to XBB.1.5. Moreover, the F456L mutation in EG.5.1 conferred heightened resistance to certain RBD class-1 mAbs. In contrast, XBC.1.6 was more sensitive to neutralization by sera and mAbs than the XBB subvariants. Notably, XBB breakthrough sera retained only weak neutralization activity against XBB subvariants. In summary, EG.5.1 and XBC.1.6 exhibited distinct antibody evasion properties. The recent global expansion of EG.5.1 might be attributable, in part, to its enhanced neutralization resistance. That XBB breakthrough infections did not elicit a robust antibody neutralization response against XBB subvariants is indicative of immunological imprinting. The high prevalence of XBC.1.6 in Australia is not due to enhanced antibody evasion.

microbiology↗

bioRxiv2022

Embryonic Vitamin D Deficiency Programs Hematopoietic Stem Cells to Induce Type 2 Diabetes

Environmental factors may alter the fetal genome to cause metabolic diseases. It is unknown whether embryonic immune cell programming impacts the risk of type 2 diabetes in later life. We demonstrate that transplantation of fetal hematopoietic stem cells (HSCs) made vitamin D deficient in utero induces diabetes in vitamin D-sufficient mice. Vitamin D deficiency epigenetically suppresses Jarid2 expression and activates the Mef2/PGC1a pathway in HSCs, which persists in recipient bone marrow, resulting in adipose macrophage infiltration. These macrophages secrete miR106-5p, which promotes adipose insulin resistance by repressing PIK3 catalytic subunit alpha and AKT signaling. Vitamin D-deficient monocytes from human cord blood have comparable Jarid2/Mef2/PGC1a expression changes and secrete miR-106b-5p, causing adipocyte insulin resistance. These findings suggest that vitamin D deficiency during development has epigenetic consequences impacting the systemic metabolic milieu.

physiology↗

bioRxiv2019

Computationally guided high-throughput design of self-assembling drug nanoparticles

Nanoformulations are transforming our capacity to effectively deliver and treat a myriad of conditions. However, many nanoformulation approaches still suffer from high production complexity and low drug loading. One potential solution relies on harnessing co-assembly of drugs and small molecular excipients to facilitate nanoparticle formation through solvent exchange without the need for chemical synthesis, generating nanoparticles with up to 95% drug loading. However, there is currently no understanding which of the millions of possible combinations of small molecules can result in the formation of these nanoparticles. Here we report the development of a high-throughput screening platform coupled to machine learning to enable the rapid evaluation of such nanoformulations. Our platform identified 101 novel self-assembling drug nanoparticles from 2.1 million pairings derived from 788 candidate drugs with one of 2686 excipients, spanning treatments for multiple diseases and often harnessing well-known food additives, vitamins, or approved drugs as carrier materials - with potential for accelerated approval and translation. Given their long-term stability and potential for clinical impact, we further characterize novel sorafenib-glycyrrhizin and terbinafine-taurocholic acid nanoparticles ex vivo and in vivo. We anticipate that this platform could accelerate the development of safer and more efficacious nanoformulations with high drug loadings for a wide range of therapeutics.

bioengineering↗