bioRxiv Science⌕ Search

Biology subjects

Zhi, Z.

Publications and source records attributed to Zhi, Z..

5 recordsLinked to original sources

Nature-inspired Nanoparticle Adiposomes Enable Targeted Delivery of Hydrophobic Drug for Anti-Cancer Treatment

The predominance of hydrophobic molecules in drug pipelines poses a fundamental delivery challenge in the aqueous physiological environment. Inspired by the endogenous lipid-transport machinery of lipid droplets and lipoproteins, adiposome was developed as a biocompatible platform for hydrophobic drug delivery. Here, docetaxel (DTX) was selected as a model hydrophobic chemotherapeutic agent to evaluate the therapeutic versatility of adiposome. Non-targeted DTX-loaded adiposomes (DTX-Ad) reduced systemic toxicity by avoiding the allergenic excipients Tween 80 and ethanol used in commercial DTX formulations. The cytotoxic mechanism and intracellular responses of DTX-Ad were comprehensively characterized. To boost antitumor efficacy, three tumor-targeting DTX-Ad formulations were subsequently engineered. Lung-targeting DTX-adiposomes (Lung@DTX-Ad), mediated by AAM-B1-28-CRGDK fusion peptide/NRP1 axis, enhanced antitumor efficacy in a lung metastasis model. BCMA-targeting DTX-adiposomes (BCMA@DTX-Ad), conferred by biotin-avidin-mediated antibody conjugation, achieved sustained suppression in a multiple myeloma model. Liver-targeting DTX-adiposomes (Liver@DTX-Ad), enabled by the ApoE/LDLR axis, outperformed both commercial DTX injection and sorafenib in hepatocellular carcinoma models. Taken together, these results demonstrate adiposome as a promising and broadly applicable drug delivery platform, with considerable potential for clinical translation across diverse malignancies.

cancer biology↗

A high-resolution dimeric structure reveals a critical role of alpha-helix 9 in apoptotic Bax pore assembly in the mitochondrial membrane

Bax functions as a proapoptotic protein perforating the mitochondrial membrane to release mitochondrial proteins and DNA that kill the cell. Structures of full-length Bax monomer in solution and core domain dimers in solution and bound to lipid/detergent bicelles reveal how Bax proteins must be activated, unfold, refold and dimerize prior to forming oligomeric pores in the membrane. In particular, amphipathic core dimer forms part of the pore wall between the nonpolar lipid bilayer and the aqueous conduit. However, atomic resolution structures of other parts of the pore were scarce. Here, we elucidate a structure of Bax C-terminal -helix 9 (9) in lysolipid micelles using NMR. According to this high-resolution structure the 9 regions form an amphipathic helical dimer with an extended nonpolar interface and several uncharged polar residues on the surface. Structure-guided mutagenesis and functional assessment demonstrate that the nonpolar interactions are important for Bax dimerization in and perforation of the mitochondrial membrane. Surprisingly the polar residues are also important because they form bifurcated hydrogen bonds between helical turns to stabilize each helix and thereby the dimer. Molecular dynamics simulations of an oligomer constructed with wall-forming core and transmembrane 9 dimers linked by flexible 6-7-8 bridges in a mitochondrial lipid bilayer generate an atomic resolution model for a stable Bax pore capable to release cytochrome C. Thus, we made an important step toward elucidating molecular mechanisms of apoptotic Bax perforation.

biochemistry↗

Limited microglial metabolic improvement with time-restricted feeding in diet-induced obesity

Time-restricted eating has shown promise for improving metabolic health in obese humans via incompletely resolved mechanisms. In this study, we investigated how time-restricted feeding (TRF) at different times of the day affects microglial immunometabolism using Wistar rats. We found that in high-fat diet (HFD)-fed obese rats, TRF during the active phase reduced fat mass, altered rhythmicity of the microglial transcriptome, and prevented an increase in hypothalamic microglia. These effects were dampened or absent with TRF during the resting phase. However, a HFD-induced microglial immunometabolic phenotype, characterized by reduced electron transport chain and increased lipid metabolism gene expression, and metabolic inflexibility, was not reversed by TRF in either the active or resting phase, indicating that reprogrammed microglial metabolism in obesity is a persistent cellular functional change that requires further study.

immunology↗

lncRNA-RMST functioned as a SOX2 transcription co-regulator to regulate miR-1251 in the progression of Hirschsprung's disease

Hirschsprungs disease (HSCR) is a congenital disorder characterized by the absence of enteric neural crest cells (ENCCs). Non-coding RNAs including long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) have been authenticated as important regulators of biological functions. We conducted a microarray analysis and found lncRNA Rhabdomyosarcoma 2-associated transcript (RMST) was down-regulated in the stenotic segment of HSCR patients. MiR-1251 is transcribed from the intron region of RMST and was also low-expressed. When the expression of RMST or miR-1251 was reduced, the cell proliferation and migration were attenuated. However, RMST didnt affect the expression of miR-1251 directly found in this study. Through bioinformatic analysis, transcription factor SOX2 was predicted to bind to the promoter region of miR-1251 which was confirmed by CHIP assay. Herein, we demonstrated that RMST exerted as a co-regulator of SOX2 to regulate the expression of miR-1251. Furtherly, AHNAK was proved to be the target gene of miR-1251 in this study. Taken together, we revealed the role of RMST/SOX2/miR-1251/AHNAK pathway in the occurrence of Hirschsprungs disease and provided a potential therapeutic target for this disease. SUMMARY STATEMENTHirschsprung disease (HSCR) is characterized by a deficit in enteric neurons, however, the underlying mechanism remains unclear. This study revealed the role of lnc-RMST during the occurrence of HSCR.

cell biology↗

Adiposome Targeting and Enzymatic Activity of Lipid Droplet-Specific Proteins

New strategies to decode the specific protein targeting mechanism on lipid droplet (LD) are urgently needed. Using adiposome, the LD binding of perilipin 2 (PLIN2), perilipin 3 (PLIN3), and adipose triglyceride lipase (ATGL) were studied. Scatchard analysis found that the binding of PLIN2 to the adiposome surface was saturable, pointing to a specific membrane binding partner. Phosphatidylinositol (PI) was found to inhibit PLIN2 binding while it did not impede PLIN3. Structural analysis combined with mutagenesis revealed that the 73rd glutamic acid of PLIN2 is significant for the effect of PI on the protein binding. The presence of PI significantly stimulated the activity of ATGL in vitro. The phosphorylation site mutants of ATGL were found reducing the lipase activity in the adiposome system. Our study demonstrates the utility of adiposome as a powerful, manipulatable model system for the characterization of LD binding and enzymatic activity of LD proteins in vitro.

biochemistry↗