Development of novel PROTAC Small-Molecule Degraders of MDM2 Protein and Peptidomimetic Inhibitors Targeting WDR5-MLL1 Protein-Protein Interaction

The transcription factor p53 plays an important role in suppression of tumor development, as it is involved in several important regulation of cell process, such as activation of DNA repair, cell cycle arrest, apoptosis and senescence. About 50% of human cancers carry mutated or deleted TP53, the gene coding p53 protein, which renders p53 nonfunctional as a tumor suppressor. Even in cancer cells with wild-type TP53, the p53 functions are inhibited by several mechanisms. Human MDM2 protein is a primary, endogenous cellular inhibitor of the tumor suppressor p53 through a direct protein-protein interaction, which makes it an attractive target for cancer treatment. In the past 15 years, a number of potent, selective and efficacious MDM2 inhibitors have been developed and advanced into clinical trials for cancer treatment. Recently, targeting protein degradation using small molecules emerged as a novel strategy for drug development. Herein, we present our design, synthesis and evaluation of MDM2 degraders based on a proteolysis targeting chimera (PROTAC) strategy. One of our most promising compounds (LE-102) could effectively induce MDM2 degradation at a concentration as low as 1 nM within 0.5 hour in RS4;11 leukemia cells. LE-102 achieves an IC50 value of 2.3 nM in cell growth inhibition of RS4;11 with wild-type p53. It can also induce complete and durable tumor regression in vivo against RS4;11 xenograft tumors in mice and can significantly extend the survival time in the RS4;11 survival model. Mechanism studies have shown that LE-102 is a highly potent and efficacious MDM2 degrader. The development of MDM2 degraders is a novel efficient strategy targeting MDM2 for cancer therapy. Inducing MDM2 protein degradation by PROTACs has shown its promising potential in cancer treatment. While during our study, a class of compounds based on the core structure of our MDM2 inhibitor MI-1061, failed to induce degradation of their consensus target, they displayed pronounced cell proliferation inhibition effects in several cancer cell lines. The cell growth inhibition activity of LD-277, a compound in this class, is not related to MDM2 degradation and activation of p53 pathway but mediated through the cereblon-dependent ubiquitination and degradation of the translation termination factor GSPT1. These findings demonstrated that a small modification could convert a PROTAC to molecular glue with unexpected mechanisms and effects. Careful target validation and activity evaluation are required in the development of PROTACs and molecular glue. MLL1 is a histone H3 Lysine 4 methyltransferase, an important regulator of transcription and mediator of normal development and disease. Translocation of MLL1 has been found widely in infant ALL and AML. Persistent activation of HoxA9 and MEIS1 caused by MLL1 fusions is important for sustaining the leukemic phenotype. Although MLL1 fusion proteins are oncogenic, they require the maintenance of a wild-type allele for leukemogenesis. WDR5 is important for the HMT activity of the wild-type MLL1 complex. Therefore, inhibition of WDR5-MLL1 protein-protein interaction could be a valid approach for the treatment of MLL-rearranged leukemias. Herein, we report the design, synthesis and evaluation of macrocyclic peptidomimetics that bind to WDR5 and block the WDR5-MLL protein-protein interaction. LC-337 binds to WDR5 with a Ki value 800 times better than the previously reported compound MM-401.PHDMedicinal ChemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/145791/1/ybsli_1.pd

Targeting Mll1 H3K4 methyltransferase activity to guide cardiac lineage specific reprogramming of fibroblasts

Generation of induced cardiomyocytes (iCMs) directly from fibroblasts offers a great opportunity for cardiac disease modeling and cardiac regeneration. A major challenge of iCM generation is the low conversion rate. To address this issue, we attempted to identify small molecules that could potentiate the reprogramming ability towards cardiac fate by removing inhibitory roadblocks. Using mouse embryonic fibroblasts as the starting cell source, we first screened 47 cardiac development related epigenetic and transcription factors, and identified an unexpected role of H3K4 methyltransferase Mll1 and related factor Men1 in inhibiting iCM reprogramming. We then applied small molecules (MM408 and MI503) of Mll1 pathway inhibitors and observed an improved efficiency in converting embryonic fibroblasts and cardiac fibroblasts into functional cardiomyocyte-like cells. We further observed that these inhibitors directly suppressed the expression of Mll1 target gene Ebf1 involved in adipocyte differentiation. Consequently, Mll1 inhibition significantly decreased the formation of adipocytes during iCM induction. Therefore, Mll1 inhibitors likely increased iCM efficiency by suppressing alternative lineage gene expression. Our studies show that targeting Mll1 dependent H3K4 methyltransferase activity provides specificity in the process of cardiac reprogramming. These findings shed new light on the molecular mechanisms underlying cardiac conversion of fibroblasts and provide novel targets and small molecules to improve iCM reprogramming for clinical applications

Quantitative study of microscopic formation water distribution in tight gas reservoirs based on the thermogravimetric method

The microscopic characterization of the distribution of formation water in tight gas reservoirs has always been one of the challenges in the industry. The traditional nuclear magnetic resonance method has certain limitations in characterizing the microscopic distribution of formation water. Thermogravimetric analysis can correlate with mass, and combined with nuclear magnetic resonance spectra, it can further optimize the characterization method for the microscopic distribution of formation water. Multiple tight sandstone gas reservoirs are vertically developed in the Shenfu Block of the Ordos Basin. Due to the strong heterogeneity of the reservoir, given the complexity of the characterization of the microscopic occurrence law of formation water, the typical argillaceous tight sandstone reservoirs Qian 5 and Tai 2 members are selected as the research objects. The distribution characteristics of the microscopic formation water of the tight gas reservoir in the Shenfu block were quantitatively characterized by the thermogravimetric method using dry distillation experiment, nuclear magnetic resonance experiment, and displacement experiment. The results show that 35°C is the boundary temperature between free water and microporous water. According to the characterization of various types of water occurrence in clay and tight sandstone by thermogravimetric experiment, free water below 35°C, microporous water (including capillary water and adsorbed water on the surface of mineral particles) in the range of 35°C–427°C, and clay-bound water (crystal water, structural water/carboxyl water) above 427°C. The type of water occurrence in tight sandstone is consistent with that of clay minerals, but the amount of water occurrence and water loss rate are different. From the perspective of water occurrence, microporous water is typically the most abundant form, while in terms of water loss rate, free water generally exhibits the highest rate. The full-scale quantitative study of micro-formation water distribution in tight gas reservoirs based on the thermogravimetric method has important guiding significance for solving the accurate characterization of water saturation logging in tight gas reservoirs, and enriches the understanding of the occurrence characteristics and laws of micro-formation water in tight gas reservoirs

Organic-rich shale in Lianggaoshan Formation: study on macroscopic and microscopic mechanical properties and mechanism of influencing factors

This study investigates the mechanical properties of organic-rich shale from the Lianggaoshan Formation using uniaxial and triaxial tests, nanoindentation, and atomic force microscopy. Key parameters such as elastic modulus and hardness are analyzed with NanoScope Analysis software. The results indicate that flat-laminated shale outperforms corrugated-laminated shale in terms of fracturing potential. As laminae increase, rock strength decreases, enhancing fracability, while thicker laminae hinder fracturing. The elastic modulus trend is clay minerals > calcite > quartz > pyrite, with Youngâs modulus negatively correlated with mineral deformation

A study on the status of myopia and pre-myopia among primary school students in different regions of Shaanxi Province, China

ObjectiveThis cross-sectional study aimed to investigate the geographic disparities in myopia and pre-myopia prevalence among elementary school students across three distinct regions of Shaanxi Province (southern Hanzhong, Guanzhong, and northern Yulin) to inform region-specific myopia control strategies.MethodsFrom March to May 2024, we employed multistage cluster sampling to recruit 8,207 eligible students (2,724 southern Shaanxi, 2,761 Guanzhong, 2,722 northern Shaanxi) from 12 randomly selected primary schools. Comprehensive ophthalmic examinations including uncorrected visual acuity and non-cycloplegic autorefraction were conducted. Continuous variables were expressed as mean ± standard deviation, while categorical variables were analyzed using chi-square tests.ResultsAge-standardized myopia prevalence was highest in northern Shaanxi (48.02%), followed by central Shaanxi/Guanzhong (42.96%) and southern Shaanxi (30.43%). Gender disparities persisted across all regions, with female students exhibiting significantly elevated myopia rates (southern Shaanxi: 34.00% vs. 26.91%; Guanzhong: 48.02% vs. 37.99%; northern Shaanxi: 52.54% vs. 44.13%; P < 0.05 for all comparisons). Pre-myopia prevalence displayed an inverse geographic pattern (southern Shaanxi: 40.60% > Guanzhong: 34.19% > northern Shaanxi: 33.73%; χ2 = 185.3, P < 0.001), with male students consistently showing higher pre-myopia detection rates than females (southern Shaanxi: 42.45% vs. 38.73%; Guanzhong 38.28% vs. 30.01%; northern Shaanxi: 37.64% vs. 29.17%; P < 0.05). A marked grade-level progression was observed, with myopia prevalence increasing annually while pre-myopia rates declined significantly.ConclusionOur findings reveal a north–south gradient in ocular health outcomes, with northern Shaanxi demonstrating concerningly high myopia prevalence coupled with reduced pre-myopia detection rates. The persistent female predominance in myopia burden and early detection gaps underscores the need for gender-sensitive interventions. The observed progression patterns suggest critical windows for prevention, advocating for: (1) Preschool-initiated vision protection programs, (2) Establishment of digital refractive registries for high-risk cohorts, and (3) Implementation of regionally tailored myopia control protocols prioritizing northern districts

Increasing the safety and efficacy of chimeric antigen receptor T cell therapy

Abstract Chimeric antigen receptor (CAR) T cell therapy is a promising cancer treatment that has recently been undergoing rapid development. However, there are still some major challenges, including precise tumor targeting to avoid off-target or “on-target/off-tumor” toxicity, adequate T cell infiltration and migration to solid tumors and T cell proliferation and persistence across the physical and biochemical barriers of solid tumors. In this review, we focus on the primary challenges and strategies to design safe and effective CAR T cells, including using novel cutting-edge technologies for CAR and vector designs to increase both the safety and efficacy, further T cell modification to overcome the tumor-associated immune suppression, and using gene editing technologies to generate universal CAR T cells. All these efforts promote the development and evolution of CAR T cell therapy and move toward our ultimate goal—curing cancer with high safety, high efficacy, and low cost

Characteristics of Landscape Change Patterns at Three Distinct Stages of the Construction and Operation of the Three Gorges Reservoir From 1986 to 2017

Abstract Analyses of landscape change patterns that are based on elevation and slope can not only provide reasonable interpretations of landscape patterns but can also help to reveal evolutionary laws. As a complex geographical unit, the ecosystem environment in the middle reach of the Yangtze River has experienced great changes due to the construction of the Three Gorges Reservoir (TGR) and its associated human activities. Here, based mainly on a digital elevation model (DEM) and remotely sensed images from 1986, 2000, 2010, and 2017 and by using GIS technology, buffer analysis, landscape element change and landscape pattern indices, the spatial and temporal evolution characteristics of different elevations, slopes, and buffer landscape types were analyzed in a typical watershed, as well as an evolutionary model of the landscape pattern. The results indicated that (1) the landscape elements along the land classification and buffer zone that were influenced by the TGR construction have undergone a phased change, with the period 2000-2010 being the most dramatic period of landscape evolution during the impoundment period; (2) landscape type shifts from human-dominated farmland to nature-driven forestland and shrub-land as elevations, slopes and buffer distances increased. The landscape has shifted from diversity to relative homogeneity. (3) land types and buffer zones have exhibited a significant effect on the landscape pattern index, which is reflected in the differences in landscape type indices for spatial extension and temporal characteristics. The results of this study illustrate the pronounced effect of the TGR on landscape patterns, and these findings will elucidate the scientific basis and provide a reference for sustainable land resource management in the study region.</jats:p