Biology subjects

Biancucci, M.

Publications and source records attributed to Biancucci, M..

5 recordsLinked to original sources

bioRxiv2024

Impact of mutations in the HEADING DATE 1 gene on transcription and cell wall composition of rice

Plants utilize environmental information to modify their developmental trajectories for optimal survival and reproduction. Over a century ago, day length (photoperiod) was identified as a major factor influencing developmental transitions, particularly the shift from vegetative to reproductive growth. In rice, exposure to day lengths shorter than a critical threshold accelerates flowering, while longer days inhibit this process. This response is mediated by HEADING DATE 1 (Hd1), a zinc finger transcription factor that is central in the photoperiodic flowering network. Hd1 acts as a repressor of flowering under long days but functions as a promoter of flowering under short days. However, the transcriptional organization of this dual function is still not fully understood. In this study, we utilized RNA-Seq to analyze the transcriptome of hd1 mutants under both long and short day conditions. We identified genes involved in the phenylpropanoid pathway that are deregulated under long days in the mutant. Quantitative profiling of cell wall components and abiotic stress assays suggest that Hd1 is involved in processes considered unrelated to flowering control. This indicates that day length perception and responses are intertwined with physiological processes beyond flowering.

plant biology↗

bioRxiv2022

Structural and Computational Design of a SARS-CoV-2 Spike Antigen with Increased Receptor Binding Domain Exposure and Improved Immunogenicity

Emerging SARS-CoV-2 variants of concern challenge the efficacy of approved vaccines and emphasize the need for improved antigens. Using an evolutionary-based design approach starting from the widely used engineered Spike antigen, S-2P, we sought to increase antigen production levels and the exposure of highly conserved and neutralization sensitive receptor-binding domain (RBD) epitopes. Thirty-six prototypes were generated in silico, of which fifteen were produced and tested in biochemical assays. Design S2D14, which contains 20 mutations within the Spike S2 domain, showed a 6-fold increase in expression while preserving similar thermal stability and antigenicity as S-2P. Cryo-EM structures indicate that the dominant populations of S2D14 particles have RBDs in exposed states, and analysis of these structures revealed how modifications within the S2 domain balance trimer stability and RBD accessibility through formation and removal of hydrogen bonds and surface charge alterations. Importantly, vaccination of mice with adjuvanted S2D14 resulted in higher levels of neutralizing antibodies than adjuvanted S-2P against SARS-CoV-2 Wuhan strain and four variants of concern. These results can guide the design of next generation vaccines to combat current, and future coronaviruses and the approaches used may be broadly applicable to streamline the successful design of vaccine antigens.

immunology↗

bioRxiv2021

Spatial differences in stoichiometry of EGR phosphatase and Microtubule-Associated Stress Protein 1 control root meristem activity during drought stress.

During moderate severity drought and low water potential ({psi}w) stress, poorly understood signaling mechanisms restrict both meristem cell division and subsequent cell expansion. We found that the Clade E Growth-Regulating 2 (EGR2) protein phosphatase and Microtubule Associated Stress Protein 1 (MASP1) differed in their stoichiometry of expression across the root meristem and had opposing effects on root meristem activity at low {psi}w. Ectopic MASP1 or EGR expression increased or decreased, respectively, root meristem size and root elongation during low {psi}w stress. This, along with the ability of phosphomimic MASP1 to overcome EGR suppression of root meristem size and observation that ectopic EGR expression had no effect on unstressed plants, indicated that during low {psi}w EGR activation and attenuation of MASP1 phosphorylation in their overlapping zone of expression determines root meristem size and activity. Ectopic EGR expression also decreased root cell size at low {psi}w. Conversely, both the egr1-1egr2-1 and egr1-1egr2-1masp1-1 mutants had similarly increased root cell size; but, only egr1-1egr2-1 had increased cell division. These observations demonstrated that EGRs affect meristem activity via MASP1 but affect cell expansion via other mechanisms. Interestingly, EGR2 was highly expressed in the root cortex, a cell type important for growth regulation and environmental response. One Sentence SummarySpatial differences in EGR-MASP1 expression and control of MASP1 phosphorylation adjust root meristem activity to regulate growth during drought stress. The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantcell.org) is: Paul E. Verslues (paulv@gate.sinica.edu.tw).

plant biology↗

bioRxiv2020

Cell cycle arrest following pan-RAS inhibition can occur through upregulation of p27 in both KRAS-dependent and KRAS-independent colon cancer cell lines

Ras-specific proteases to degrade RAS within cancer cells are under active development as an innovative strategy to treat tumorigenesis. The naturally occurring biological toxin effector called RAS/RAP1-specific endopeptidase (RRSP) is known to cleave all RAS within a cell, including HRAS, KRAS, NRAS and mutant KRAS G13D. In the course of studies developing RRSP as an anti-cancer therapeutic, it was shown that cleavage of total RAS by RRSP results in a range of cell fates from cytotoxicity to moderate growth inhibition. Despite the considerable amount of evidence demonstrating RRSP anti-tumor effects in vivo, our understanding of the mechanisms involved are unknown. Here, we first demonstrate, using isogenic mouse fibroblasts expressing a single isoform of RAS or mutant KRAS, that RRSP equally inactivates all isoforms of RAS as well as the major oncogenic KRAS mutants. The cleavage of RAS inhibited phosphorylation of ERK and cell proliferation regardless of the RAS isoform. To investigate further how RAS processing might lead to varying outcomes in cell fate within cancer cells, we tested RRSP against four colorectal cancer cell lines with a range of cell fates. While cell lines highly susceptible to RRSP (HCT116 and SW1463) undergo cytotoxic death, RRSP treatment of GP5d cells induces G1 cell cycle arrest, and SW620 cells instead induces growth inhibition through cell senescence. In three of four cell lines tested, growth effects were dictated by rescued expression of the tumor suppressor protein p27 (Kip1). The ability of RRSP to inactivate all RAS and inhibit cancer cell growth through a variety of mechanisms highlights the antitumor potential of RRSP, and further warrants investigation as a potential anti-tumor therapeutic.

cancer biology↗

bioRxiv2019

Inhibition of tumor growth by a novel engineered chimeric toxin that cleaves activated mutant and wild-type RAS

Despite nearly four decades of effort, broad inhibition of oncogenic RAS using small molecule approaches has proven to be a major challenge. Here we describe the development of a novel pan-RAS biologic inhibitor comprised of the RAS-RAP1-specific endopeptidase fused to the protein delivery machinery of diphtheria toxin. We show that this engineered chimeric toxin irreversibly cleaves and inactivates intracellular RAS at low picomolar concentrations terminating downstream signaling in receptor-bearing cells. Further, we demonstrate in vivo target engagement and reduction of tumor burden in three mouse xenograft models driven by either wild-type or mutant RAS. Intracellular delivery of a potent anti-RAS biologic through a receptor-mediated mechanism represents a promising new approach to developing RAS therapeutics against a broad array of cancers. SignificanceRAS oncoproteins have long been considered among the most elusive drug targets in cancer research. At issue is the lack of accessible drug binding sites and the extreme affinity for its GTP substrate. Covalent inhibitors against the KRAS G12C mutant have shown early clinical promise, however, targeting the other oncogenic RAS mutants across three RAS isoforms has proven challenging. Inhibition of activated wild-type RAS in the absence of canonical RAS mutations is also highly desirable in certain tumors. Here, we demonstrate delivery of an extremely potent pan-RAS and RAP1 cleaving enzyme in therapeutic quantities to specific receptor-bearing cells in vitro and in vivo. We aim to advance this approach to engineer the first targeted pan-RAS inhibitor for cancer therapy. One Sentence SummaryEngineered chimeric toxin halts tumor growth in vivo via RAS cleavage

cancer biology↗