Biomedical subjects

Hong Chen

Publications and source records attributed to Hong Chen.

At least 19 recordsLinked to original sources

PubMed2026

Effect of a digitally augmented general health promotion intervention on abstinence from health-risk behaviors among emergency department discharge patients: A randomized controlled trial.

BACKGROUND: Noncommunicable diseases (NCDs) are the leading global cause of death and are driven by modifiable behaviors, such as tobacco use, harmful alcohol consumption, unhealthy diet, and physical inactivity. Recognizing that emergency department (ED) visits represent a unique opportunity to promote behavior change, this trial evaluated a digitally augmented, theory based general health promotion approach, combining a brief telephone-based intervention with mobile instant messaging support, to help discharged ED patients abstain from health risk behaviors. METHODS AND FINDINGS: This assessor-blinded randomized controlled trial was conducted in a major public hospital ED in Hong Kong. Adults (18-65 years) triaged as semi-urgent or non-urgent and with ≥1 health-risk behavior and smartphone access were randomized to receive a digitally augmented, theory‑based general health‑promotion intervention consisting of a brief telephone‑based AWARD‑model intervention (Ask, Warn, Advise, Refer, and Do-it-again) followed by weekly WhatsApp or WeChat messages for 6 months, or to a control group receiving brief telephone advice only. The primary outcome was self-report abstinence from ≥1 health-risk behavior at 6 months; secondary outcomes included the proportion of participants who achieved self-reported abstinence from ≥1 health-risk behavior at 12 months and reduction in the number of behaviors at 6 and 12 months. Of the 2,134 screened patients, 572 were enrolled (286 per group). At 6 months, 30.1% of the intervention participants versus 19.9% of the controls achieved self-reported abstinence (RR = 1.51; 95% CI, 1.13-2.02; P = 0.006). The intervention also significantly increased the likelihood of fewer risky behaviors at 6 (RR = 1.54; P = 0.01) and 12 (RR = 1.48; P = 0.02) months. Physical inactivity showed the greatest improvement at 6 months (31.7% versus 16.2%; P < 0.001). The effects attenuated after cessation of booster messaging. Limitations include reliance on self-reported outcomes, the single-center study design, and loss to follow-up, which may have affected the generalizability of the results. CONCLUSIONS: A digitally augmented, theory-based general health promotion strategy delivered at ED discharge through brief telephone intervention and mobile instant messaging support demonstrated short-term benefits in promoting self-reported abstinence and reducing health-risk behaviors at 6 months. However, the absence of a sustained effect at 12 months suggests that extended support or maintenance strategies may be required to maintain these improvements over time. Multicenter trials with longer follow-up are warranted to evaluate long-term effectiveness. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov (Registration No: NCT06077565).

Humans↗

PubMed2026

A species-discriminatory aerA TaqMan qPCR assay for rapid quantification of Aeromonas veronii in fish tissues and aquaculture water.

Aeromonas veronii is a major bacterial pathogen in freshwater aquaculture, yet rapid species-level quantification remains challenging within the genetically complex genus Aeromonas. We developed a singleplex hydrolysis-probe (TaqMan) quantitative PCR (qPCR) assay targeting an A. veronii-discriminatory region of the aerolysin gene (aerA) and validated it according to MIQE recommendations. Plasmid standards gave a linear range of 2 to 2 × 106 copies/reaction (R2 = 0.9962) with 100.5% amplification efficiency. The endpoint limit of detection was 2 copies per reaction, and 20 copies per reaction was set as the practical reporting limit based on reproducible detection and low intra- and inter-assay variation. Analytical specificity was evaluated with genomic DNA from an 18-strain panel, with reproducible amplification observed only for A. veronii. The assay was further tested in 55 fish-tissue and 11 aquaculture-water DNA extracts. NH8B-1D2 sample-process monitoring was used for matrix-level recovery correction, and tissue and water extraction blanks were undetermined. The aerA target was detected in all tested gill, stomach/intestine, spleen, kidney/head kidney, pond-water filter and Xiamen seawater filter extracts, and in 10/11 liver extracts. Median NH8B-corrected loads were highest in gill among tissues and higher in pond-water filters than in Xiamen seawater filters. A separate Vibrio harveyi inhibition-check assay indicated no obvious amplification-stage inhibition. This assay supports rapid quantification of aerA-positive A. veronii in fish and aquaculture-water matrices.

Animals↗

PubMed2026

ITPRIPL1: A tumor immune-associated biomarker with prognostic and therapeutic implications in gastrointestinal cancer.

Inositol 1,4,5-trisphosphate receptor-interacting protein-like 1(ITPRIPL1) has recently been implicated in tumor-immune regulation, yet its tumor-type specificity and clinical relevance in gastrointestinal malignancies remain unclear. Here, we performed an integrative analysis of ITPRIPL1 across stomach adenocarcinoma (STAD), colon adenocarcinoma (COAD), rectal adenocarcinoma (READ), and esophageal carcinoma (ESCA) using bulk transcriptomics, immune pathway analyses, survival modeling, single-cell RNA sequencing, immunofluorescence validation, and therapeutic correlation analyses. Although ITPRIPL1 was upregulated across gastrointestinal cancers, its prognostic significance was highly tumor-specific, with elevated expression consistently predicting unfavorable survival only in STAD. In gastric cancer, ITPRIPL1 expression was closely associated with immune-related pathways and genomic instability features, and its prognostic association varied across immune contexts, particularly according to CD8⁺/CD4⁺ T-cell abundance, with an exploratory association also observed for zeta-chain-associated protein kinase 70 (ZAP70) expression. Single-cell and immunofluorescence analyses demonstrated preferential enrichment of ITPRIPL1 in T cells and tumor-adjacent immune structures. Notably, Exploratory analyses further showed that higher ITPRIPL1 expression was associated with favorable survival outcomes in selected external pretreatment immunotherapy cohorts and with lower IC50 values for several agents in cancer cell-line pharmacogenomic datasets. Collectively, these findings identify ITPRIPL1 as an immune-associated biomarker with primary clinical relevance in gastric cancer.

Humans↗

PubMed2026

A smartphone-integrated Pt@Cu-HCF nanozyme-based paper sensor for on-site determination of total antioxidant capacity in marine oils.

Total antioxidant capacity (TAC) serves as a key indicator for evaluating the nutritional quality of foods. In this study, we designed a platinum-embedded copper hexacyanoferrate (denoted as Pt@Cu-HCF) nanozyme that exhibits high oxidase-like activity, efficiently catalyzing the oxidation of chromogenic substrates to generate robust colorimetric signals. Antioxidants quench hydroxyl radicals (∙OH) produced during the catalytic process, leading to a concentration-dependent suppression of the color signal. Leveraging this mechanism, a smartphone-integrated, colorimetric paper sensor for on-site TAC quantification was developed, using vitamin E as the calibration standard. The sensor was applied to determine TAC in fish oil, algal oil, and krill oil, demonstrating a linear response range of 9.78-312.5 μM and a limit of detection (LOD) of 6.41 μM. Validation using real-world marine oil samples showed excellent agreement with a commercial assay kit, confirming the reliability and practical applicability of this portable sensor for TAC measurement in complex biological matrices.

Antioxidants↗

PubMed2026

Depressive Symptoms and Smoking Cessation Among Adolescents and Young Adults Who Smoke: A Prospective Cohort Study.

PURPOSE: This study examined the bidirectional prospective associations between depressive symptoms and smoking cessation among adolescent and young adults who smoke. METHODS: Data on 1,151 participants aged ≤25 years who smoke and receive peer-led quitline counseling in Hong Kong (2016-2022) were analyzed. Exposures included baseline depressive symptoms and smoking cessation (self-reported 7-day abstinence) at 1, 3, and 6 months; Outcome measures included smoking cessation at 1, 3, and 6 months and depressive symptoms at 6 months. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression Scale, with a score ≥16 indicating at risk for depression. RESULTS: More severe baseline depressive symptoms were associated with lower odds of smoking cessation at 1, 3, and 6 months, which reversely was associated with lower depressive symptoms at 6 months (all p < .05). Similarly, being at risk for depression at baseline was associated with lower odds of smoking cessation at 1 (adjusted odds ratio [aOR] .66, 95% confidential interval [CI] .47-.93) and 3 months (aOR .71, 95% CI .52-.97). Conversely, smoking cessation at 1 (aOR .40, 95% CI .23-.69), 3 (aOR .58, 95% CI .37-.92), and 6 months (aOR .44, 95% CI .29-.69) was associated with lower odds of at risk for depression at 6 months. DISCUSSION: More severe depressive symptoms were prospectively associated with lower odds of smoking cessation, while smoking cessation was associated with lower depressive symptoms and risk for depression. Integrated interventions simultaneously addressing psychological needs and smoking are warranted, when delivered in smoking cessation programs or embedded within mental health services for youth who smoke.

Humans↗

PubMed2026

FOXC2 and WT1 regulate transcriptional reprogramming during the podocyte response to injury.

Transcriptional reprogramming has an important role in kidney glomerular disease. Using in vivo murine models of podocyte injury, we studied the roles of the FOXC2 and WT1 transcription factors (TFs) in podocyte injury. Podocytes are a crucial cell type of glomeruli, the filtration units of each nephron. Podocyte injury is often the incipient event leading to chronic kidney disease. It is well established that the TFs FOXC2 and WT1 are required in podocytes to maintain the glomerular filtration barrier. Their role in the response to injury is less well understood. Here, we tested the hypothesis that FOXC2 and WT1 act together to mediate transcriptional reprogramming in response to podocyte injury. Similarly to that of WT1, genome-wide FOXC2 binding to target genes is dynamic during the course of injury, initially increasing, but late in injury there is a dramatic decrease in FOXC2 expression and in its binding to target genes. Podocyte-specific inactivation of FoxC2 or Wt1 in adult mice limits the transcriptional response to injury. Correlating FOXC2 and WT1 ChIP-seq analyses demonstrated that they co-bind many genes expressed in podocytes. Thus, reprogramming the transcriptome involves dynamic changes in the binding of FOXC2 and WT1 to their target genes during a reparative injury response.

Animals↗

PubMed2026

PIEZO1 Mediates Myoblast Proliferation Under Simulated Microgravity.

Skeletal muscle atrophy is a major health risk of prolonged spaceflight, yet how microgravity reshapes muscle cells through mechanotransduction remains poorly understood. Here, we examined the mechanosensitive cation channel PIEZO1 in myoblast proliferation under simulated microgravity. Using a two-dimensional clinostat combined with Hi-C-based 3D genomics, transcriptomics, and functional assays, we found that simulated microgravity promotes C2C12 myoblast proliferation and upregulates Piezo1. Piezo1 mRNA knockdown reduced both proliferation and depolarization-induced Ca2 + influx, each partially restored under simulated microgravity, consistent with PIEZO1 being a central mediator of the response. Simulated microgravity also drove extensive 3D genome reorganization alongside changes in proliferation-related gene expression. Integrating chromatin architecture with transcriptomics, we found that PIEZO1 inhibition increased Elavl2 mRNA expression, PIEZO1 activation suppressed Elavl2 mRNA expression, and Elavl2 mRNA knockdown enhanced cell proliferation. These findings define a PIEZO1-ELAVL2 mechanotransduction axis, coupled to 3D chromatin remodeling, that regulates myoblast proliferation under simulated microgravity, and thus may be a target for countering spaceflight-associated muscle dysfunction.

Cell Proliferation↗

PubMed2024

Angiopoietin-like protein 8 directs DNA damage responses towards apoptosis by stabilizing PARP1-DNA condensates.

Upon genotoxic stresses, cells employ various DNA damage responses (DDRs), including DNA damage repair or apoptosis, to safeguard genome integrity. However, the determinants among different DDRs choices are largely unknown. Here, we report angiopoietin-like protein 8 (ANGPTL8), a secreted regulator of lipid metabolism, localizes to the nucleus and acts as a dynamic switch that directs DDRs towards apoptosis rather than DNA repair after genotoxin exposure. ANGPTL8 deficiency alleviates DNA damage and apoptosis in cells exposed to genotoxins, as well as in the liver or kidney of mice injured by hepatic ischemia/reperfusion or cisplatin treatment. Mechanistically, ANGPTL8 physically interacts with Poly (ADP-ribose) polymerase 1 (PARP1), in a PARylation-independent manner, and reduces the fluidity of PARP1-DNA condensates, thereby enhancing the pro-apoptotic accumulation of PARP1 and PAR chains on DNA lesions. However, the transcription of ANGPTL8 is gradually decreased following genotoxin treatment, partly due to downregulation of CCAAT enhancer binding protein alpha (CEBPA), presumably to avoid further cytotoxicity. Together, we provide new insights by which genotoxic stress induced DDRs are channeled to suicidal apoptosis to safeguard genome integrity.

Animals↗

PubMed2017

Circular RNA profiling reveals an abundant circLMO7 that regulates myoblasts differentiation and survival by sponging miR-378a-3p.

Circular RNAs (circRNAs) have been identified from various tissues and species, but their regulatory functions during developmental processes are not well understood. We examined circRNA expression profiles of two developmental stages of bovine skeletal muscle (embryonic and adult musculus longissimus) to provide first insights into their potential involvement in bovine myogenesis. We identified 12 981 circRNAs and annotated them to the Bos taurus reference genome, including 530 circular intronic RNAs (ciRNAs). One parental gene could generate multiple circRNA isoforms, with only one or two isoforms being expressed at higher expression levels. Also, several host genes produced different isoforms when comparing development stages. Most circRNA candidates contained two to seven exons, and genomic distances to back-splicing sites were usually less than 50 kb. The length of upstream or downstream flanking introns was usually less than 105 nt (mean≈11 000 nt). Several circRNAs differed in abundance between developmental stages, and real-time quantitative PCR (qPCR) analysis largely confirmed differential expression of the 17 circRNAs included in this analysis. The second part of our study characterized the role of circLMO7-one of the most down-regulated circRNAs when comparing adult to embryonic muscle tissue-in bovine muscle development. Overexpression of circLMO7 inhibited the differentiation of primary bovine myoblasts, and it appears to function as a competing endogenous RNA for miR-378a-3p, whose involvement in bovine muscle development has been characterized beforehand. Congruent with our interpretation, circLMO7 increased the number of myoblasts in the S-phase of the cell cycle and decreased the proportion of cells in the G0/G1 phase. Moreover, it promoted the proliferation of myoblasts and protected them from apoptosis. Our study provides novel insights into the regulatory mechanisms underlying skeletal muscle development and identifies a number of circRNAs whose regulatory potential will need to be explored in the future.

Animals↗

PubMed2007

Activation of the ATF3 gene through a co-ordinated amino acid-sensing response programme that controls transcriptional regulation of responsive genes following amino acid limitation.

Expression of ATF3 (activating transcription factor 3) is induced by a variety of environmental stress conditions, including nutrient limitation. In the present study, we demonstrate that the increase in ATF3 mRNA content following amino acid limitation of human HepG2 hepatoma cells is dependent on transcriptional activation of the ATF3 gene, through a highly co-ordinated amino acid-responsive programme of transcription factor synthesis and action. Studies using transient over-expression and knockout fibroblasts showed that several ATF and C/EBP (CCAAT/enhancer-binding protein) family members contribute to ATF3 regulation. Promoter analysis showed that a C/EBP-ATF composite site at -23 to -15 bp relative to the transcription start site of the ATF3 gene functions as an AARE (amino acid response element). Chromatin immunoprecipitation demonstrated that amino acid limitation increased ATF4, ATF3, and C/EBPbeta binding to the ATF3 promoter, but the kinetics of each was markedly different. Immediately following histidine removal, there was a rapid increase in histone H3 acetylation prior to an enhancement in ATF4 binding and in histone H4 acetylation. These latter changes closely paralleled the initial increase in RNA pol II (RNA polymerase II) binding to the promoter and in the transcription rate from the ATF3 gene. The increase in ATF3 and C/EBPbeta binding was considerably slower and more closely correlated with a decline in transcription rate. A comparison of the recruitment patterns between ATF and C/EBP transcription factors and RNA polymerase II at the AARE of several amino acid-responsive genes revealed that a highly co-ordinated response programme controls the transcriptional activation of these genes following amino acid limitation.

Activating Transcription Factor 3↗

PubMed2007

Targeting the exogenous htPAm gene on goat somatic cell beta-casein locus for transgenic goat production.

Combining gene targeting of animal somatic cells with nuclear transfer technique has provided a powerful method to produce transgenic animal mammary gland bioreactor. The objective of this study is to make an efficient and reproducible gene targeting in goat fetal fibroblasts by inserting the exogenous htPAm cDNA into the beta-casein locus with liposomes or electroporation so that htPAm protein might be produced in gene-targeted goat mammary gland. By gene-targeting technique, the exogenous htPAm gene was inserted to milk goat beta-casein gene sequences. Fetal fibroblasts were isolated from Day 35 fetuses of Guanzhong milk goats, and transfected with linear gene-targeting vector pGBC4htPAm using Lipefectamin-2000 and electoporation, respectively. Forty-eight gene-targeted cell colonies with homologous recombination were obtained, and three cell colonies were verified by DNA sequence analysis within the homologous recombination region. Using gene-targeted cell lines as donor cells for nuclear transfer, a total of 600 reconstructed embryos had been obtained, and 146 developed cloned embryos were transferred to 16 recipient goats, and finally three goats showed pregnancy at Day 90.

Animals↗

PubMed2007

mtDNA diversity and genetic lineages of eighteen cattle breeds from Bos taurus and Bos indicus in China.

In order to clarify the origin and genetic diversity of indigenous cattle breeds in China, we carried out phylogenetic analysis of representatives of those breeds by employing mitochondrial gene polymorphism. Complete cyt b gene sequences, 1140 bp in length, were determined for a total of 136 individuals from 18 different breeds and these sequences were clustered into two distinct genetic lineages: taurine (Bos taurus) and zebu (Bos indicus). In analysis of the cyt b gene diversity, Chinese cattle showed higher nucleotide (0.00923) and haplotype diversity (0.848) than the reports from other studies, and the animals from the taurine lineage indicated higher nucleotide diversity (0.00330) and haplotype diversity (0.746) than the ones from the zebu lineage (0.00136; 0.661). The zebu mtDNA dominated in the southern breeds (63.3-100%), while the taurine dominated in the northern breeds (81.8-100%). Six cattle breeds from the central area of China exhibited intermediate frequencies of zebu mtDNA (25-71.4%). This polymorphism revealed a declining south-to-north gradient of female zebu introgression and a geographical hybrid zone of Bos taurus and Bos indicus in China.

Animals↗

PubMed2006

Assay and characterization of a strong promoter element from B. subtilis.

A new strong promoter fragment isolated from Bacillus subtilis was identified and characterized. Using the heat stable beta-galactosidase as reporter, the promoter fragment exhibited high expression strength both in Escherichia coli and B. subtilis. The typical prokaryotic promoter conservation regions were found in the promoter fragment and the putative promoter was identified as the control element of yxiE gene via sequencing assay and predication of promoter. To further verify and characterize the cloned strong promoter, the putative promoter was sub-cloned and the beta-Gal directed by the promoters was high-level expressed both in E. coli and B. subtilis. By means of the isolated promoter, an efficient expression system was developed in B. subtilis and the benefit and usefulness was demonstrated through expression of three heterologous and homogenous proteins. Thus, we identified a newly strong promoter of B. subtilis and provided a robust expression system for genetic engineering of B. subtilis.

Bacillus subtilis↗

PubMed2006

Structure-function analysis reveals discrete beta3 integrin inside-out and outside-in signaling pathways in platelets.

A unique aspect of integrin receptor function is the transmission of bidirectional signals. In platelets alphaIIbbeta3 integrins require "inside-out" signals to bind fibrinogen and form thrombi. Following ligand binding, alphaIIbbeta3 integrins generate "outside-in" signals that contribute to thrombus stability. Because integrin cytoplasmic tails are short and lack enzymatic activity, bidirectional signals are believed to be mediated by interactions with intracellular proteins, but the molecular basis for integrin signal transduction remains poorly understood. In the present study we have used retroviral vectors to express alphaIIbbeta3 integrins with mutant beta3 tails in mouse platelets and test mechanisms of bidirectional signaling. Using this approach we identify mutations (eg, beta3Y747A) that confer loss of signaling in both directions and others (eg, beta3T762A) that confer a selective loss of outside-in signals. These results reveal the presence of discrete bidirectional signaling pathways controlled by integrin beta subunits in platelets and describe a high-throughput means of further investigating these pathways in vivo.

Animals↗

PubMed2006

Preparation of Au coated polystyrene beads and their application in an immunoassay.

A novel immunoassay method based on polystyrene beads coated with Au nanoparticles (Au@PS) is described. Au nanoparticles were prepared by reductive reaction, and then deposited on the surface of polystyrene beads to form Au coatings. Results indicated that the Au coatings had good stability and that human IgG was immobilized at a concentration of 16 microg/g Au@PS. FITC-labeled rabbit-anti-human IgG and FITC-labeled rabbit-anti-goat IgG were employed to react with the human IgG on Au@PS. Fluorescence imaging results showed that the reaction had good immuno-specificity. In addition, further experiments at the single-bead level indicated that the linear range was 0.05-15 microg/ml, and that the FITC signal could be detected even when the target antibody concentration was as low as 0.01 microg/ml. The assay results were compared with an enzyme-linked immunosorbent assay (ELISA), and showed relatively good reliability.

Animals↗

PubMed2006

Expression, purification, and characterization of secreted recombinant human insulin-like growth factor-binding protein-6 in methylotrophic yeast Pichia pastoris.

The mitogenic and metabolic activities of insulin-like growth factors (IGF) are modulated by a family of six high-affinity IGF-binding proteins (IGFBPs). This study describes the secretion and purification of the recombinant human IGFBP-6 expressed in methylotrophic yeast Pichia pastoris. In this research, a multicopy expression plasmid pA-O815/3xIGFBP-6 containing 3 copies of human IGFBP-6 expression cassette was constructed and transformed into P. pastoris GS115. The encoding sequence of alpha-factor leading peptide fused in-frame at the 5' end of human IGFBP-6 open reading frame and led expressed IGFBP-6 into the secretory pathway. After transformed cells were induced with methanol, medium supernatant was analyzed by SDS-PAGE and Western blotting. The two major protein bands of approximately 30 and approximately 18kDa were detected. The protein of approximately 30kDa was confirmed to be the glycosylated recombinant human IGFBP-6 (rhIGFBP-6), which was partially proteolyzed by protease Kex2 to produce a approximately 18kDa fragment. Approximately 95% homogeneity of the soluble form of 30kDa rhIGFBP-6 were achieved by two-step purification procedure using ion-exchange chromatography and then hydrophobic-interaction chromatography. The rhIGFBP-6 could be distributed to all of the cell body when cultured MDA-MB-231 cell with rhIGFBP-6 and the activities of rhIGFBP-6 were assayed by [(3)H]thymidine incorporation, which revealed that rhIGFBP-6 inhibited IGF-II-stimulated cell proliferation. Our results demonstrated that functional rhIGFBP-6 can be produced in sufficient quantities by using P. pastoris for further structural and functional studies.

Gene Expression↗

PubMed2006

High-speed observation of cavitation bubble cloud structures in the focal region of a 1.2 MHz high-intensity focused ultrasound transducer.

Cavitation bubble clouds in the focal region of HIFU play important roles in therapeutic applications of HIFU. Temporal evolution and spatial distribution of cavitation bubble clouds generated in the focal region of a 1.2 MHz single element concave HIFU transducer in water are investigated by high-speed photography. It is found that during the initial 600 micro s insonation cavitation bubble clouds organize to the "screw-like structure" or "cap-like structure". The screw-like structure is characterized by a nearly fixed tip at the geometrical focus of the HIFU transducer, and the cap-like structure is marked by a dent formed in the direction of ultrasound transmission. After 600 micro s, another two structures are recorded - "streamer structure" and "cluster structure". The streamer structure is also featured by a nearly fixed bottom position at the focus, while the cluster structure is distinguished by agglomerations of bubbles around the focus.

Journal Article↗

PubMed2006

Functional characterization of heterogeneous nuclear ribonuclear protein C1/C2 in vitamin D resistance: a novel response element-binding protein.

Clinically apparent hereditary vitamin D-resistant rickets (HVDRR) usually results from a loss of function mutation in the vitamin D receptor (VDR). We recently described a human with the classical HVDRR phenotype but normal VDR function. Hormone resistance resulted from constitutive overexpression of heterogeneous nuclear ribonucleoprotein (hnRNP) that competed with a normally functioning VDR-retinoid X receptor (RXR) dimer for binding to the vitamin D response element (VDRE). Here we describe the purification, molecular cloning, and expression of this vitamin D resistance-causing, competitive response element-binding protein (REBiP) hnRNP C1/C2. When overexpressed in vitamin D-responsive cells, cDNAs for both hnRNPC1 and hnRNPC2 inhibited VDR-VDRE-directed transactivation (28 and 43%, respectively; both p < 0.005). By contrast, transient expression of an hnRNP C1/C2 small interfering RNA increased VDR transactivation by 39% (p < 0.005). Chromatin immunoprecipitation of nucleoproteins bound to the transcriptionally active 1,25-dihydroxy vitamin D-driven CYP24 promoter revealed the presence of REBiP in vitamin D-responsive human cells and indicated that the normal pattern of 1,25-dihydroxy vitamin D-initiated cyclical movement of the VDR on and off the VDRE is legislated by competitive, reciprocal occupancy of the VDRE by hnRNP C1/C2. The temporal and reciprocal pattern of VDR and hnRNPC1/C2 interaction with the VDRE was lost in HVDRR cells overexpressing the hnRNP C1/C2 REBiP. These observations provide further evidence for the functional importance of REBiP as a component of the multiprotein complex involved in the regulation of vitamin D-mediated transcription. In particular, chromatin immunoprecipitation data suggest that, in addition to its RNA-processing functions, hnRNP C1/C2 may be a key determinant of the temporal patterns of VDRE occupancy.

Amino Acid Sequence↗