Biomedical subjects

Guoping Li

Publications and source records attributed to Guoping Li.

10 recordsLinked to original sources

PubMed2025

A hypoxia-responsive tRNA-derived small RNA confers renal protection through RNA autophagy.

Transfer RNA-derived small RNAs (tsRNAs or tDRs) perform a range of cellular functions. Here, we showed that tRNA-Asp-GTC-3'tDR, a hypoxia-induced tDR derived from the 3' end of tRNA-Asp-GTC, activated autophagic flux in kidney cells and its silencing blocked autophagic flux. Functional gain-/loss-of-function studies in murine kidney disease models demonstrated a substantial renoprotective function of tRNA-Asp-GTC-3'tDR. Mechanistically, tRNA-Asp-GTC-3'tDR assembled stable G-quadruplex structures and sequestered pseudouridine synthase 7 (PUS7), preventing catalytic pseudouridylation of histone mRNAs. The resulting pseudouridylation deficiency directed histone mRNAs to the autophagosome-lysosome pathway, triggering RNA autophagy. This tDR-induced RNA autophagy pathway was activated during murine and human kidney diseases, suggesting clinical relevance. Thus, tRNA-Asp-GTC-3'tDR plays a role in regulating RNA autophagy, which helps to maintain homeostasis in kidney cells and protects against kidney injury.

Animals↗

PubMed2025

The extracellular vesicle transcriptome provides tissue-specific functional genomic annotation relevant to disease susceptibility in obesity.

We characterized circulating extracellular vesicles (EVs) in obese and lean humans, identifying transcriptional cargo differentially expressed in obesity (277 unique genes; false discovery rate < 10%). Since circulating EVs may have broad origin, we compared this obesity EV transcriptome with expression from human visceral-adipose-tissue-derived EVs from freshly collected and cultured biopsies from the same obese individuals, observing high concordance. Using a comprehensive set of adipose-specific epigenomic and chromatin conformation assays, we found that the differentially expressed transcripts from the EVs were those regulated in adipose by body mass index-associated SNPs (p < 5 × 10-8) from a large-scale genome-wide association study (GWAS). Using a phenome-wide association study of the regulatory SNPs for the EV-derived transcripts, we identified a substantial enrichment for inflammatory phenotypes, including type 2 diabetes. Collectively, these findings represent the convergence of the GWAS (genetics), epigenomics (transcript regulation), and EV (liquid biopsy) fields, enabling powerful future genomic studies of complex diseases.

Humans↗

PubMed2024

Self-quenched tRNA reporters for imaging tRNA-derived RNA biogenesis.

tRNA-derived small RNAs (tDRs) are an emerging class of small non-coding RNAs that play crucial roles in various cellular processes. However, there is a paucity of data on their sub-cellular localization due to a lack of tools and reagents to image tDRs. Imaging tDRs remains challenging due to the similar sequences between tDR and its parent tRNA. Here, we describe an innovative tool for studying the formation and localization of tDRs in various biological processes using a self-quenched tDR biogenesis reporter. This method utilizes a full-length tRNA molecule conjugated with both fluorescence and quencher groups at 5'- and 3'- ends. In its intact state, the fluorescence is quenched. Upon cleavage by specific ribonucleases and strand separation, the fluorescence becomes detectable, allowing real-time imaging of tDR biogenesis. This protocol details the design, synthesis, and application of this reporter, including transfection procedures and imaging techniques. The method offers a powerful approach for investigating tDR dynamics in living cells, providing insights into their roles in cellular processes and stress responses.

RNA, Transfer↗

PubMed2006

Identification of lipid binding and lipoprotein lipase activation domains of human apoAV.

ApoAV, a newly discovered apolipoprotein, plays a key role in human triglyceride homeostasis; however, the structure-function correlation of apoAV is not clearly understood. To explore the relationship, wild type and six deletion mutants, that is (AV (Delta(1-51)), AV (Delta(51-128)), AV (Delta(132-188)), AV (Delta(192-238)), AV (Delta(246-299)), AV (Delta(301-343))), of human apoAV expressed in Escherichia coli were studied. All the deleted regions together encompass almost the entire 343 amino acid sequence of wild type apoAV. Circular dichroism spectroscopy showed that the alpha helical content of lipid-free wild type apoAV was 46%. In comparison with wild type apoAV, AV (Delta(192-238)) and AV (Delta(301-343)) displayed significantly decreased lipid binding activities, confirming the importance of these two regions in lipid binding function of apoAV. While, the LPL activation function of apoAV remarkably impaired after deletion of residues 192-238. These findings suggested that the domain (192-238) is absolutely necessary for apoAV in lipid binding and lipoprotein lipase activation.

Animals↗

PubMed2006

Purification and characterization of a staphylokinase variant, K35R.

DGR [staphylokinase (Sak) variant K35R, in which lysine (K) at position 35 is replaced by arginine (R)], a recombinant mutant of the Staphylococcus aureus enzyme, is a promising drug for thrombotic disorders. In the present work, DGR was successfully overexpressed by the plasmid JF1125[pST-DGR] as a soluble cytoplasmic protein in a 30-litre fermentor that accounted for more than 50% of the total cellular protein. The expressed DGR was subsequently purified by using a simple three-step chromatographic purification process developed at a pilot scale. The clearance of host-cell-protein contaminants in the protein purification process was confirmed by SDS/PAGE and Western blotting, using rabbit antisera raised against Escherichia coli JF1125 cell proteins. SDS/PAGE, isoelectric focusing and HPLC-MS analysis indicated that the purified DGR is almost completely homogeneous. The purification process resulted in greater-than-98% pure DGR and yielded up to 25.0 mg/g wet weight of cells. The effect of pH and temperature on the stability of DGR was investigated further. The results showed that DGR was highly stable at neutral pH and more stable than two other wild-type Saks, SakSTAR and Sak42D, when submitted to high temperatures.

Bioreactors↗

PubMed2006

Therapeutic effects of DNA vaccine on allergen-induced allergic airway inflammation in mouse model.

Vaccination with DNA encoding Dermatophagoides pteronyssinus group 2 (Der p 2) allergen previously showed its effects of immunologic protection on Der p 2 allergen-induced allergic airway inflammation in mice. In present study, we investigated whether DNA vaccine encoding Der p 2 could exert therapeutic role on allergen-induced allergic airway inflammation in mouse model and explored the mechanism of DNA vaccination in asthma specific-allergen immunotherapy. After sensitized and challenged by Der p 2, the BALB/c mice were immunized with DNA vaccine. The degrees of cellular infiltration were scored. IgE levels in serum and IL-4/IL-13 levels in BALF were determined by ELISA. The lung tissues were assessed by histological examinations. Expressions of STAT6 and NF-kappaB in lung were determined by immunohistochemistry staining. Vaccination of mice with DNA vaccine inhibited the development of airway inflammation and the production of mucin induced by allergen, and reduced the level of Der p 2-specific IgE level. Significant reductions of eosinophil infiltration and levels of IL-4 and IL-13 in BALF were observed after vaccination. Further more, DNA vaccination inhibited STAT6 and NF-kappaB expression in lung tissue in Der p 2-immunized mice. These results indicated that DNA vaccine encoding Der p 2 allergen could be used for therapy of allergen-induced allergic airway inflammation in our mouse model.

Animals↗

PubMed2004

Cyclooxygenase-2 parallels invasive depth and increased MVD in transitional cell carcinoma.

To investigate the relationship between the expression of cyclooxygenase-2 (COX-2), and invasive depth and angiogenesis in human transitional cell carcinoma (TCC), the expression of COX-2 and von Willebrand factor (vWF) was detected in paraffin-embedded transitional cell carcinoma specimens from 50 patients with histologically confirmed bladder transitional cell carcinoma. Microvessels were counted and microvessel density (MVD) was calculated. The correlation between COX-2 and invasive depth, MVD and invasive depth, COX-2 and MVD were analyzed. COX-2 expression was significantly related to the invasive depth of tumors; it solely expressed in invasive TCC. The ratio of COX-2 positively stained samples in each stage correlated to the invasive stages; so did the proportion of COX-2 (+) cells in whole tumor cells. Also, MVD increased with the invasive stages of tumors and positively correlated to the invasive depth. The COX-2-positive TCC samples were highly vascular, their microvessel density was significantly higher than that of the COX-2-negative TCC samples. There was a positive correlation between MVD and COX-2 (+) cells proportion. Our findings suggested that COX-2 was positively correlated with the invasive depth and involved in the process of angiogenesis in human transitional cell carcinoma.

Carcinoma, Transitional Cell↗

PubMed2004

Changes of uPA and uPA-R expression in the cornea after alkali burn.

PURPOSE: To investigate the expression levels of uPA and uPA-R in corneal repair after alkali burn. METHODS: The corneal alkali burn models were established in vitro and in vivo, then immunocytochemistry (ICC) of uPA/uPA-R and image analysis and statistical evaluation were performed to determine their expression levels both in vitro and in vivo. RESULTS: Compared with control group, the expressions of uPA and uPA-R after alkali burn had no significant increases till 6h, then increased rapidly from 12h to 24h and reached their maxima at 24h. From 24h, their expression levels decreased rapidly. In vivo, they rebounded again after 48h and attained their second peaks at 96h, respectively. After that, their expressions decreased again. The uPA-positive reaction mainly distributed in the cytoplasm while that of uPA-R mostly distributed on the cellular membrane. Their expression changes were similar to each other, both in vivo and in vitro. In vivo, uPA and uPA-R expressed and gathered in the basal layer of corneal epithelium. CONCLUSIONS: These results suggest that the time phase of 24h after wound is the typical stage associating with the expressional maximum of uPA and uPA-R both in vivo and in vitro. Furthermore, the results also imply that the expression changes of uPA and uPA-R correlate to the wound healing after the corneal alkali burn, uPA and uPA-R coordinate with each other to stimulate the wound healing.

Animals↗

PubMed2004

Activation of signal transducer and activator of transcription 5 (STAT5) in splenocyte proliferation of asthma mice induced by ovalbumin.

To investigate the role of signal transducer and transcriptional activator 5 (STAT5) activated in ovalbumin (OVA)-induced splenocyte proliferation of asthma mice, an asthma mouse model was set up by intraperitoneal injection and aspiration of OVA with nebulizer. The proliferation of splenocytes isolated from the asthma mice was detected by [3H] thymidine incorporation. The phosphorylation of STAT5 was examined by Western blotting and STAT5-DNA binding was measured by electrophoretic mobility shift assay (EMSA). OVA could pronouncedly induce the splenocyte proliferation of asthma mice in a dose-dependent manner compared with control groups. Phosphorylation of STAT5 and STAT5-DNA binding were observed in splenocytes from asthma mice induced by OVA at 1 h and 3 h. These results indicated that STAT5 signal pathway played an important role in lymphocyte proliferation of asthma mice induced by OVA.

Animals↗

PubMed2002

Cyclooxygenase-2 increased the angiogenic and metastatic potential of tumor cells.

It seems certain that COX-2 is related to tumor and some data suggested that COX-2 might have relation to tumor malignance and angiogenesis. In order to elucidate the relationship between COX-2 and tumor invasive and angiogenic ability, we transfected human transitional cell carcinoma (TCC) cell line, EJ, permanently with a COX-2 expression vector or the mock vector. The EJ-COX(2) cells, which overexpressed COX-2, acquired increased invasiveness and angiogenic ability by activation of VEGF, uPA, and MMP-2. Increased invasiveness and angiogenic ability were reversed by treatment with either selective COX-2 inhibitor, NS-398, or dual COX inhibitor, indomethacin. These results demonstrate that overexpression of COX-2 can lead to phenotypic changes that alter the metastatic and angiogenic potential of TCC cancer cells.

Carcinoma, Transitional Cell↗