Biomedical subjects

Huan Xie

Publications and source records attributed to Huan Xie.

7 recordsLinked to original sources

PubMed2026

Integrated Bulk and Single-Cell RNA-Seq Analysis Reveals Transcriptional Activation of PTGS2 by FOS in Progression From T2DM to T2DM-Associated NAFLD.

Type 2 diabetes mellitus (T2DM) and nonalcoholic fatty liver disease (NAFLD) frequently coexist, exacerbating disease burden. However, the molecular mechanisms underlying the progression from T2DM to T2DM-associated NAFLD remain unclear. This study investigated the regulatory function of FOS-mediated PTGS2 activation in this transition. We integrated bulk RNA-seq data from GEO, single-cell transcriptomic data and transcriptomes from patients with T2DM-associated NAFLD. Differentially expressed genes were identified using the limma package, and T2DM-related gene modules were defined by weighted gene co-expression network analysis. LASSO regression and random forest identified 14 candidate genes, with PTGS2 and FOS prioritised. Single-cell analysis showed increased FOS and PTGS2 expression in monocytes, CD8+ T cells and Kupffer cells. Transcription factor prediction and dual-luciferase assays confirmed that FOS directly binds the PTGS2 promoter and drives its transcription. In vitro, FOS silencing decreased PTGS2 expression, cytokine secretion and apoptosis under high-glucose and free fatty acid conditions, whereas PTGS2 overexpression exacerbated inflammation and apoptosis independently of FOS expression. These findings demonstrate that FOS transcriptionally activates PTGS2, contributing to hepatic inflammation and apoptosis during the progression from T2DM to NAFLD. PTGS2 may serve as a promising biomarker and therapeutic target for T2DM-associated NAFLD.

Single-Cell Gene Expression Analysis↗

PubMed2006

Hepatitis B virus inhibiting constituents from Herpetospermum caudigerum.

From the ethanol extract of the seeds of Herpetospermum caudigerum wall, one new lignan compound 1, was isolated and characterized along with three known compounds 2, 3 and 4. The structure elucidation of the isolated new compound was performed on the basis of spectroscopic and chemical evidence. The structures of known compounds were determined by comparison of spectral data and physical data with those previously reported. The activity inhibiting hepatitis b virus was evaluated. Preliminary studies showed that compound 1 and 2 displayed promising inhibitory potential against hepatitis b virus.

Antiviral Agents↗

PubMed2005

Assembly and characterization of biomolecule-gold nanoparticle conjugates and their use in intracellular imaging.

In this chapter, we outline protocols for assembling and characterizing peptide-gold nanoparticle conjugates. We describe two strategies for attaching peptides to gold nanoparticles. One involves the covalent coupling of cysteine-terminated peptides directly to a particle surface via a sulfur-gold bond. Alternatively, peptides are coupled to bovine serum albumin (BSA) via a bifunctional molecular crosslinker. We also describe a number of characterization methods for determining the number of crosslinkers per BSA, peptides per BSA, and peptides adsorbed per particle. Finally, we show that the enormous visible light extinction properties of gold nano particles make them excellent imaging agents for tracking the trajectories of peptides inside living cells.

Animals↗

PubMed2004

Preparation of protein gradients through the controlled deposition of protein-nanoparticle conjugates onto functionalized surfaces.

This paper describes a simple method for the preparation and characterization of protein density gradients on solid supports. The method employs colloidal metal nanoparticles as protein carriers and optical tags and is capable of forming linear, exponential, 1D, 2D, and multiprotein gradients of varying slope without expensive or sophisticated surface patterning techniques. Surfaces patterned with proteins using the procedures described within are shown to support cell growth and are thus suitable for studies of protein-cell interactions.

Animals↗

PubMed2003

Critical flocculation concentrations, binding isotherms, and ligand exchange properties of peptide-modified gold nanoparticles studied by UV-visible, fluorescence, and time-correlated single photon counting spectroscopies.

Protocols for modifying gold nanoparticles with peptide-bovine serum albumin (BSA) conjugates are described within. The resulting constructs were characterized using a number of techniques including static fluorescence spectroscopy and time-correlated single photon counting spectroscopy (TCSPC) in order to quantify peptide-BSA binding isotherms, exchange rates, critical flocculation concentrations, and the composition of mixed peptide-BSA monolayers on gold nanoparticles. TCSPC has proven to be a powerful technique for observing the microenvironment of protein-gold nanoparticle conjugates because it can distinguish between surface-bound and solution-phase species without the need for separation steps. Full characterization of the composition and stability of peptide-modified metal nanoparticles is an important step in their use as intracellular delivery vectors and imaging agents.

2,2'-Dipyridyl↗

PubMed2003

Multifunctional gold nanoparticle-peptide complexes for nuclear targeting.

The ability of peptide-modified gold nanoparticles to target the nucleus of HepG2 cells was explored. Five peptide/nanoparticle complexes were investigated, particles modified with (1) the nuclear localization signal (NLS) from the SV 40 virus; (2) the adenovirus NLS; (3) the adenovirus receptor-mediated endocytosis (RME) peptide; (4) one long peptide containing the adenovirus RME and NLS; and (5) the adenovirus RME and NLS peptides attached to the nanoparticle as separate pieces. Gold nanoparticles were used because they are easy to identify using video-enhanced color differential interference contrast microscopy, and they are excellent scaffolds from which to build multifunctional nuclear targeting vectors. For example, particles modified solely with NLS peptides were not able to target the nucleus of HepG2 cells from outside the plasma membrane, because they either could not enter the cell or were trapped in endosomes. The combination of NLS/RME particles (4) and (5) did reach the nucleus; however, nuclear targeting was more efficient when the two signals were attached to nanoparticles as separate short pieces versus one long peptide. These studies highlight the challenges associated with nuclear targeting and the potential advantages of designing multifunctional nanostructured materials as tools for intracellular diagnostics and therapeutic delivery.

Amino Acid Sequence↗

PubMedDate not supplied

Cellular trajectories of peptide-modified gold particle complexes: comparison of nuclear localization signals and peptide transduction domains.

Gold nanoparticles modified with nuclear localization peptides were synthesized and evaluated for their subcellular distribution in HeLa human cervical epithelium cells, 3T3/NIH murine fibroblastoma cells, and HepG2 human hepatocarcinoma cells. Video-enhanced color differential interference contrast microscopy and transmission electron microscopy indicated that transport of nanoparticles into the cytoplasm and nucleus depends on peptide sequence and cell line. Recently, the ability of certain peptides, called protein transduction domains (PTDs), to transclocate cell and nuclear membranes in a receptor- and temperature-independent manner has been questioned (see for example, Lundberg, M.; Wikstrom, S.; Johansson, M. (2003) Mol. Ther. 8, 143-150). We have evaluated the cellular trajectory of gold nanoparticles carrying the PTD from HIV Tat protein. Our observations were that (1) the conjugates did not enter the nucleus of 3T3/NIH or HepG2 cells, and (2) cellular uptake of Tat PTD peptide-gold nanoparticle conjugates was temperature dependent, suggesting an endosomal pathway of uptake. Gold nanoparticles modified with the adenovirus nuclear localization signal and the integrin binding domain also entered cells via an energy-dependent mechanism, but in contrast to the Tat PTD, these signals triggered nuclear uptake of nanoparticles in HeLa and HepG2 cell lines.

3T3 Cells↗