Biomedical subjects

Jie Zheng

Publications and source records attributed to Jie Zheng.

At least 19 recordsLinked to original sources

PubMed2026

Effects of intensive blood pressure control on cardio-kidney outcomes by KDIGO risk categories: a Post Hoc analysis of ACCORD-BP and SPRINT trials.

The effects of intensive systolic blood pressure (SBP) control on cardiovascular (CV) and kidney outcomes across different Kidney Disease Improving Global Outcomes (KDIGO) risk categories remain unclear. We performed a secondary analysis of the Systolic Blood Pressure Intervention Trial (SPRINT) and the SPRINT-eligible Action to Control Cardiovascular Risk in Diabetes Blood Pressure (ACCORD-BP) trial. Participants were categorized into low, moderate, and high/very-high KDIGO risk groups. The primary outcomes were composite adverse CV events (defined as nonfatal myocardial infarction (MI), nonfatal stroke, fatal or hospitalized heart failure (HF), and CV mortality) and composite adverse kidney events (defined as a sustained decline in eGFR of ≥ 40% and end-stage kidney disease (ESKD)). We found that intensive BP control reduced the risk of composite CV events (HR 0.68; 95% CI 0.59-0.78), with attenuated benefits in higher KDIGO risk categories (P for interaction = 0.055). This interaction was mainly driven by nonfatal MI and fatal or hospitalized HF (both P for interaction < 0.05). Intensive BP control increased the risk of composite kidney events (HR 1.88; 95% CI 1.52-2.33), mainly in low- and moderate-risk groups rather than in high/very-high risk groups (P for interaction = 0.04). Similar patterns were observed for sustained eGFR decline (P for interaction = 0.03), but not for ESKD (HR 1.05; 95% CI 0.74-1.48; P for interaction = 0.71). The KDIGO risk classification modified the effects of intensive BP control. Balancing CV benefits against potential kidney impacts in patients with different KDIGO risks during intensive BP treatment is recommended. Trial Registration: ClinicalTrials.gov Identifiers: NCT01206062 (SPRINT) and NCT00000620 (ACCORD).

Cardiovascular outcome↗

PubMed2026

The association between GLP-1R expression and cardiovascular-kidney-metabolic-related diseases in non-diabetic and non-obese population: evidence triangulation using Mendelian randomization, observational and polygenic score association analysis.

BACKGROUND: Glucagon-like peptide-1 receptor (GLP-1R) agonists are emerging as promising therapies for cardiovascular-kidney-metabolic (CKM) related diseases in individuals with type 2 diabetes mellitus (T2DM) or obesity. But their effects in non-obese and non-diabetic individuals are unclear. This study triangulates evidence using Mendelian randomization (MR), polygenic scores (PGS) and observational analyses to estimate the associations of GLP-1R expression with chronic kidney disease (CKD), heart failure (HF) and metabolic dysfunction-associated steatotic liver disease (MASLD). METHODS: For the MR analysis, instruments mimicking GLP-1R expression were identified using pancreas-specific cis-expression quantitative trait loci from GTEx (N ≤ 305). MR-Robust method was used as the primary MR approach. PGS and observational analyses were performed both in non-diabetic and non-obese individuals separately. A genome-wide association study (GWAS) for MASLD (14,231 cases and 348,091 controls) was performed in the general population using data from UK Biobank. RESULTS: GLP-1R expression showed robust effects on CKD (odds ratio [OR] 0.96, 95%CI 0.95 to 0.97, q = 1.7 × 10- 10 ), HF (OR = 0.96, 95%CI 0.94 to 0.97, q = 2.5 × 10- 8) and MASLD (OR = 0.96, 95%CI 0.93 to 0.98, q = 1.3 × 10- 3) in the general population. Consistent results were observed in validation analyses. Furthermore, PGS and observational analyses among non-T2DM and non-obese individuals found little evidence to support its association with CKD, HF or MASLD. GWAS analysis identified eight conditionally independent variants associated with MASLD, in which rs563199662 was a new signal located at TFPI region. CONCLUSIONS: This study provides multilayered evidence for GLP-1R expression in mitigating CKD, HF and MASLD risks in the general population, while de-prioritized its effect on CKM-related diseases in non-obese and non-diabetic individuals. Further clinical trials are needed to validate the effects of GLP-1R agonists in relative health population.

Humans↗

PubMed2026

The tissue-specific effects of glucose-lowering drug targets on aging mediated through DNA methylation: a multi-omics genetic study.

BACKGROUND: DNA methylation plays a key role in mediating the anti-aging effects of glucose-lowering drugs. This study aims to systematically explore the potential anti-aging effects of target genes of FDA-approved glucose-lowering drugs and the underlying epigenetic mediators. METHODS: We conducted a two-sample Mendelian randomization (MR) study to investigate the putative causal relationships between the gene expression levels of glucose-lowering drug targets and 10 aging-related phenotypes, followed by a two-step MR to estimate the mediation effect of DNA methylation. Drug candidates were selected according to the latest review of clinical drug use for type 2 diabetes, and their target genes were obtained from the DGIdb. Tissue-specific cis-expression quantitative trait loci (eQTLs) from GTEx Consortium were selected as genetic instruments to proxy the expression level of drug-target genes. Glycemic phenotypes were used as positive controls to validate the instruments. The cis- and trans-methylation QTLs of Cytosine-phosphate-Guanine sites near the drug target genes were obtained from GoDMC Consortium. Additionally, we performed enrichment analyses focused on tissue specificity and aging pathways to further corroborate our findings. RESULTS: We obtained 194 target genes interacting with 36 FDA-approved anti-diabetic drugs, of which the tissue-specific eQTLs were used to proxy the drug target effects. MR showed strong evidence that nine interacting genes of six glucose-lowering drugs showed anti-aging potential on one or more aging-related phenotypes mediated by DNA methylation: EHMT2, HSPA4, IGF2BP2, IRS1, LPL, NDUFAF1, NDUFS3, SLC22A3, and TCF7L2. These genes were distributed in 17 tissues, especially in the central nervous system, suggesting a potential neural component in their anti-aging effects. For instance, expression of EHMT2 in several brain basal ganglia regions, where the gene interacted with Tolazamide, showed a protective effect on frailty (odds ratio (OR) in caudate = 1.02, 95%CI = 1.01-1.04, FDR adjusted P = 1.69 × 10-2; OR in putamen = 1.02, 95% CI = 1.01-1.03, PFDR = 3.37 × 10-2, OR in nucleus accumbens = 1.02, 95% CI = 1.01-1.04, PFDR = 3.37 × 10-2). These associations were externally validated by searching literature evidence in existing EWAS and TWAS studies, as well as evidence from enrichment analyses. CONCLUSIONS: This study prioritizes nine glucose-lowering genes as anti-aging drug targets in specific tissues and prioritizes their epigenetic regulation through DNA methylation for future drug development.

DNA Methylation↗

PubMed2026

Life-course influence of birthweight and subsequent pathways on healthy aging: a Mendelian randomization study.

BACKGROUND: Birthweight readily measurable marker of fetal growth that may influence health across the lifespan. We aimed to investigate the potential causal association between birthweight and healthy aging and to identify the mediating roles of subsequent socioeconomic, behavioral, functional, and disease-related factors to inform life-course strategies to promote healthy aging and reduce health inequities. METHODS: We performed two-sample Mendelian randomization analyses in European-ancestry participants to estimate the effect of birthweight (n = 298,142-423,683) on two robust, composite healthy aging phenotypes (genetically independent phenotype of aging (aging-GIP) and multivariate aging-related genetic factor (mvAge)) and six individual aging phenotypes, including healthspan, resilience, parental lifespan, self-rated health, phenotypic age deceleration, and 90th percentile self-longevity (n = 34,710-1,958,774), and screened for 100 candidate mediators (n = 14,267-1,812,017) using a two-step mediation analysis. RESULTS: Genetically determined each 1-SD higher birthweight was associated with higher aging-GIP (β [95% CI] in different models ranging from 0.131 [0.066-0.196] to 0.162 [0.089-0.235] SDs) and mvAge (0.036 [0.010-0.063] to 0.045 [0.024-0.067]), independent of later-life obesity indicators; also with more interpretable benefits, including 12%-16% higher odds of longer healthspan, a 0.079-0.089 SD improvement in resilience, and a 1.22-1.74 year increase in parental lifespan. Of 100 candidates, 26 and 25 mediated the effect of birthweight on aging-GIP and mvAge, respectively, including socioeconomic indicators (education, household income, occupational attainment; individual mediation proportion: 12.72%-27.79%); behaviors (e.g., cheese intake, age at first sex; 10.38%-29.56%); physical functions (e.g., blood pressure, grip strength; 7.57%-42.65%); and cardiometabolic diseases (e.g., type 2 diabetes, cardiovascular diseases; 25.02%-70.11%). CONCLUSIONS: Higher birthweight within the normal range directly promotes healthy aging, mediated by multifaceted modifiable factors. Our findings advocate adopting a life-course approach to foster healthy aging, starting with optimal birthweight and extending to interventions that enhance socioeconomic status, promote healthy behaviors, strengthen physical functions, and prevent cardiometabolic diseases.

Mendelian Randomization Analysis↗

PubMed2026

DrdR Negatively Modulates the Expression of Flagellar Genes via Interaction With FleQ in Xanthomonas campestris.

Response regulators (RRs) of two-component signalling systems (TCSs) containing tandem receiver (REC) domains are widespread in bacteria, yet their functions and regulatory mechanisms remain poorly understood. In our previous study, DrdR, one such RR in the cruciferous black rot disease pathogen Xanthomonas campestris pv. campestris (Xcc) was demonstrated to positively regulate pilus-dependent motility and negatively regulate flagellum-dependent motility. We showed that DrdR modulates the ATPase activities of pili motor proteins PilT and PilB, thereby enhancing bacterial pilus-dependent swarming motility. However, how DrdR represses flagellar motility remained unknown. Here, we demonstrate that DrdR acts as a transcriptional repressor of flagellar gene expression. We used in vitro and in vivo approaches to identify FleQ, the master transcriptional regulator of flagellar genes, as a novel interaction partner of DrdR. Biochemical analyses revealed that DrdR binding inhibits FleQ's ATPase activity, which is essential for its transcriptional activation function. Microscale thermophoresis assays showed that DrdR reduces FleQ's DNA-binding capability to its cognate promoter. These findings collectively indicate that DrdR modulates FleQ transcriptional activity by reducing both its DNA-binding ability and ATPase activity. Our results demonstrate that DrdR serves as a specialized modulator of FleQ that acts upstream in the signalling cascade controlling the expression of flagellar genes in Xcc. This study exhibits a previously unknown mechanism whereby DrdR regulates bacterial motility. Combined with our previous finding, our data suggest that DrdR most likely acts as a conversion regulator between flagellum-dependent and pilus-dependent motility in Xcc.

Flagella↗

PubMed2025

Structure-activity relationships study on inhibition of CRISPR-Cas9 by glycosaminoglycans.

The CRISPR-Cas9 system is a revolutionary genome editing system known for its precision, simplicity and efficiency, playing a crucial role in gene-editing. It has enabled applications ranging from biomedicine to agriculture. However, the uncontrollable activity of Cas9 has raised significant safety concerns in clinical settings, limiting its broader application. Consequently, regulating CRISPR-Cas9 activity holds substantial promise for enhancing the safety and efficacy of gene-editing technologies. In this study, we demonstrated that sulfated glycosaminoglycans (GAGs) exhibit inhibitory effects of Cas9. Specifically, both chondroitin sulfate (CS) and heparin (HP) can inhibit CRISPR/Cas9 activity, with heparin showing a stronger inhibitory effect that correlates positively with its concentration. Molecular dynamics simulations indicate that sulfated heparin residues might inhibit Cas9 function by binding to essential DNA-binding sites, which are crucial for functional interactions, potentially impairing activity. Additionally, higher molecular weight GAGs exhibit enhanced inhibitory effects under the same sulphation. Notably, the sulfation site also influenced activity. C6-sulfation of chondroitin sulfate is more favorable for Cas9 inhibition, and N-sulfation of heparin enhances its inhibitory effect on Cas9 activity. These findings provide valuable insights into the development of carbohydrate-based inhibitors for CRISPR-Cas9, offering a foundation for further exploration in this field.

CRISPR-Cas Systems↗

PubMed2006

[Comparison of three staining methods for hepatitis B virus].

OBJECTIVE: To compare the advantages and disadvantages of three staining methods of HBV. METHODS: Normal Liver tissue and HBV-infected, HCV-infected, or dually infected (HBV and HCV) liver tissues were selected for this study. Formalin-fixed, paraffin-embedded sections (4 microm) were prepared. Each of the liver tissue specimens was detected by three staining methods, including immunohistochemical methods, Shikata's orcein stain and Victoria blue stain,respectively. RESULTS: In the three methods, all of six HBV-infected cases showed intense staining, and three cases with dual infection (HBV and HCV) were weakly positive. However, both normal and HCV-infected liver tissues showed no staining. HBsAg stained dark brown with Immunohistochemical stain; HBsAg containing ground-glass hepatocytes stained magenta with Shikata's orcein stain; HBsAg stained blue with Victoria blue. CONCLUSION: Each of three methods has its own advantages and disadvantages: high specificity and sensitivity, but high cost for immunohistochemical methods; complicated and overelaborate procedure for preparation of solutions, lower specificity and sensitivity, but low cost, for special staining methods.

Hepatitis B↗

PubMed2006

The influence of phosphorylation on the activity and structure of the neuronal IQ motif protein, PEP-19.

PEP-19 is a 7.6 kDa neuronally expressed polypeptide that contains a single calmodulin-binding IQ motif. The calmodulin-binding activity of several neuronal IQ motif proteins is regulated by phosphorylation of a conserved serine. We propose that the serine residue within the IQ motif of PEP-19 is phosphorylated, and that phosphorylation modifies the activity of PEP-19. Camstatin, a functionally active 25-residue fragment of PEP-19's IQ motif, binds calmodulin and inhibits neuronal nitric oxide synthase. A truncated camstatin-in which the IQ motif serine is the only phosphorylatable residue-was screened against 42 different kinases. Truncated camstatin is selectively phosphorylated by four isoforms of protein kinase C. Furthermore, treatment of full-length PEP-19 with PKCgamma catalyzes phosphorylation of the same serine residue. Fluorescent anisotropy shows that phosphorylation of camstatin inhibits its binding to calmodulin. NMR solution structures indicate that both camstatin and phospho-camstatin exist in similar dynamic turn-like conformations. This suggests that camstatin's greater affinity for calmodulin is due not to a change in the conformation of the phospho-peptide, but rather, to a disruption of hydrophobic interactions between phospho-camstatin and calmodulin caused by the presence of the hydrophilic phosphate group. The H(alpha) chemical shifts and the circular dichroism spectra of the camstatins are consistent with those of "nascent helices". We submit that PEP-19 is a PKC substrate, and that the phosphorylation state of PEP-19 may play a role in the modulation of calmodulin-dependent signaling.

Amino Acid Motifs↗

PubMed2006

The third 20 amino acid repeat is the tightest binding site of APC for beta-catenin.

Adenomatous polyposis coli (APC) plays a critical role in the Wnt signaling pathway by tightly regulating beta-catenin turnover and localization. The central region of APC is responsible for APC-beta-catenin interactions through its seven 20 amino acid (20aa) repeats and three 15 amino acid (15aa) repeats. Using isothermal titration calorimetry, we have determined the binding affinities of beta-catenin with an APC 15aa repeat fragment and each of the seven 20aa repeats in both phosphorylated and unphosphorylated states. Despite sequence homology, different beta-catenin binding repeats of APC have dramatically different binding affinities with beta-catenin and thus may play different biological roles. The third 20aa repeat is by far the tightest binding site for beta-catenin among all the repeats. The fact that most APC mutations associated with colon cancers have lost the third 20aa repeat underlines the importance of APC-beta-catenin interaction in Wnt signaling and human diseases. For every 20aa repeat, phosphorylation dramatically increases its binding affinity for beta-catenin, suggesting phosphorylation has a critical regulatory role in APC function. In addition, our CD and NMR studies demonstrate that the central region of APC is unstructured in the absence of beta-catenin and Axin, and suggest that beta-catenin may interact with each of the APC 15aa and 20aa repeats independently.

Adenomatous Polyposis Coli↗

PubMed2006

Structural stability and dynamics of an amyloid-forming peptide GNNQQNY from the yeast prion sup-35.

A seven amino acid yeast prion sup-35 fragment (GNNQQNY) forms amyloid fibrils. The availability of its detailed atomic oligomeric structure makes it a good model for studying the early stage of aggregation. Here we perform long all-atom explicit solvent molecular simulations of various sizes and arrangements of oligomer seeds of the wild-type and its mutants to study its stability and dynamics. Previous studies have suggested that the early stage rate-limiting step of oligomer formation occurs in high-order oligomers. Our simulations show that with the increase in the number of strands even from a dimer to a trimer, oligomer stability increases dramatically. This suggests that the minimal nucleus seed for GNNQQNY fibril formation could be small and is likely three or four peptides, in agreement with experiment, and that higher-order oligomers do not dissociate quickly since they have small diffusion coefficients and thus slow kinetics. Further, for the hydrophilic polar GNNQQNY, there are no hydrogen bonds and no hydrophobic interactions between adjacent beta-sheets. Simulations suggest that within the sheet, the driving forces to associate and stabilize are interstrand backbone-backbone and side chain-side chain hydrogen bonds, whereas between the sheets, shape-complementary by the dry polar steric zipper via the side chains of Asn-2, Gln-4, and Asn-6 holds the sheets together, as proposed in an earlier study. Since the polar side chains of Asn-2, Gln-4, and Asn-6 act as a hook to bind two neighboring sheets together, these geometric restraints reduce the conformational search for the correct side chain packing to a two-dimensional problem of intersheet side chain interactions. Mutant simulations show that substitution of Asn-2, Gln-4, or Asn-6 by Ala would disrupt this steric zipper, leading to unstable oligomers.

Amino Acid Sequence↗

PubMed2006

Designing a nanotube using naturally occurring protein building blocks.

Here our goal is to carry out nanotube design using naturally occurring protein building blocks. Inspection of the protein structural database reveals the richness of the conformations of proteins, their parts, and their chemistry. Given target functional protein nanotube geometry, our strategy involves scanning a library of candidate building blocks, combinatorially assembling them into the shape and testing its stability. Since self-assembly takes place on time scales not affordable for computations, here we propose a strategy for the very first step in protein nanotube design: we map the candidate building blocks onto a planar sheet and wrap the sheet around a cylinder with the target dimensions. We provide examples of three nanotubes, two peptide and one protein, in atomistic model detail for which there are experimental data. The nanotube models can be used to verify a nanostructure observed by low-resolution experiments, and to study the mechanism of tube formation.

HIV-1↗

PubMed2006

Multipotential differentiation ability of GATA-1-null erythroid-committed cells.

GATA-1, a zinc finger transcription factor, has been believed to be indispensable for the survival of proerythroblasts. However, we found that GATA-1-null proerythroblasts could survive and proliferate on OP9 stroma cells in the presence of erythropoietin. Furthermore, myeloid and mast cells were induced from the GATA-1-null proerythroblasts by the stimulation of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3), respectively, but lymphoid differentiation was not achieved by in vivo transfer. Thus, without activity of the transcription factor required for terminal differentiation, even relatively mature and committed cells proliferate continuously with the differentiation capacity to other lineages. Our data suggest that GATA-1 is a critical transcription factor to fix erythroid progenitors to the erythroid lineage.

Animals↗

PubMed2006

GFP-based FRET analysis in live cells.

Fluorescence resonance energy transfer (FRET) is a widely utilized optical technique for measuring small distances of 1-10 nm in live cells. In recent years, its application has been greatly popularized by the discovery of green fluorescent protein (GFP) and many improved variants which make good donor-acceptor fluorophore pairs. GFP-based proteins are structurally stable, relatively inert, and can be reliably attached to points of interest. The combination of easy access to the GFP-based FRET technique and its obvious usefulness in many applications can lead to complacency. Potential problems such as light contaminants, e.g., bleed-through and cross-talk, and inconsistent donor and acceptor concentrations are easily overlooked and can lead to errors in FRET calculation and data interpretation. In this article, we outline possible pitfalls of GFP-based FRET and approaches that address these issues, including a "Spectra FRET" technique that can be easily applied to live cell studies.

Animals↗

PubMed2006

Concepts and schemes for the re-engineering of physical protein modules: generating nanodevices via targeted replacements with constrained amino acids.

Physically building complex multi-molecular structures from naturally occurring biological macromolecules has aroused a great deal of interest. Here we focus on nanostructures composed of re-engineered, natural 'foldamer' building blocks. Our aim is to provide some of the underlying concepts and schemes for crafting structures utilizing such conformationally relatively stable molecular components. We describe how, via chemical biology strategies, it is further possible to chemically manipulate the foldamer building blocks toward specific shape-driven structures, which in turn could be used toward potential-designed functions. We outline the criteria in choosing candidate foldamers from the vast biological repertoire, and how to enhance their stability through selected targeted replacements by non-proteinogenic conformationally constrained amino acids. These approaches combine bioinformatics, high performance computations and mathematics with synthetic organic chemistry. The resulting artificially engineered self-organizing molecular scale structures take advantage of nature's nanobiology toolkit and at the same time improve on it, since their new targeted function differs from that optimized by evolution. The major challenge facing nanobiology is to be able to exercise fine control over the performance of these target-specific molecular machines.

Combinatorial Chemistry Techniques↗

PubMed2006

Large-scale sequence analysis of avian influenza isolates.

The spread of H5N1 avian influenza viruses (AIVs) from China to Europe has raised global concern about their potential to infect humans and cause a pandemic. In spite of their substantial threat to human health, remarkably little AIV whole-genome information is available. We report here a preliminary analysis of the first large-scale sequencing of AIVs, including 2196 AIV genes and 169 complete genomes. We combine this new information with public AIV data to identify new gene alleles, persistent genotypes, compensatory mutations, and a potential virulence determinant.

Animals↗

PubMed2006

OligoSpawn: a software tool for the design of overgo probes from large unigene datasets.

BACKGROUND: Expressed sequence tag (EST) datasets represent perhaps the largest collection of genetic information. ESTs can be exploited in a variety of biological experiments and analysis. Here we are interested in the design of overlapping oligonucleotide (overgo) probes from large unigene (EST-contigs) datasets. RESULTS: OLIGOSPAWN is a suite of software tools that offers two complementary services, namely (1) the selection of "unique" oligos each of which appears in one unigene but does not occur (exactly or approximately) in any other and (2) the selection of "popular" oligos each of which occurs (exactly or approximately) in as many unigenes as possible. In this paper, we describe the functionalities of OLIGOSPAWN and the computational methods it employs, and we report on experimental results for the overgo probes designed with it. CONCLUSION: The algorithms we designed are highly efficient and capable of processing unigene datasets of sizes on the order of several tens of Mb in a few hours on a regular PC. The software has been used to design overgo probes employed to screen a barley BAC library (Hordeum vulgare). OLIGOSPAWN is freely available at http://oligospawn.ucr.edu/.

Base Sequence↗

PubMed2006

Improvement of quantification of myocardial first-pass perfusion mapping: a temporal and spatial wavelet denoising method.

Mapping of myocardial blood flow (MBF) with first-pass perfusion imaging is becoming an important tool in the study of coronary artery disease. In this study a wavelet-based denoising method was developed to improve the accuracy of pixel-by-pixel MBF maps. We performed an in vivo study in five stenotic dogs with 70% stenosis in the left coronary arteries. First-pass perfusion imaging sessions were performed by administering the intravascular contrast agent Gadomer at rest and during dipyridamole-induced vasodilation. Color microspheres (MS) were injected into the dogs to measure MBF at the same time. After denoising was performed, the signal-to-noise ratio (SNR) of the first-pass perfusion image improved by approximately 180%, whereas spatial variation of MBF maps decreased 38%. It was also found that the correlation of MBFs measured by MRI with the MS method indicates a significant improvement with the denoising method (R2 increased from 0.24 to 0.78, P < .001). This suggests that the wavelet denoising method may be an effective way to increase the accuracy of pixel-by-pixel MBF quantification and reduce spatial variation, and may be applicable to other forms of noise-sensitive image analysis.

Animals↗

PubMed2006

Rational design and applications of a Rac GTPase-specific small molecule inhibitor.

Rac GTPases are involved in the regulation of multiple cell functions and have been implicated in the pathology of certain human diseases. Dominant negative mutants of Rac have been the tool of choice in studying Rac function in cells. Given the difficulty of introducing high concentrations of the Rac mutants into primary cells and nonspecific effects of the mutants on Rho guanine nucleotide exchange factor (GEF) activities, it is desirable to develop small molecule inhibitors that could specifically inhibit Rac activities. Here we describe the rational design, characterization, and applications of a first-generation Rac-specific small molecule inhibitor. On the basis of the structure-function information of Rac interaction with GEFs, in a computer-based virtual screening we have identified NSC23766, a highly soluble and membrane permeable compound, as a specific inhibitor of a subset of GEF binding to Rac and, therefore, Rac activation by these GEFs. In fibroblast cells, NSC23766 inhibited Rac1 GTP-loading without affecting Cdc42 or RhoA activity and suppressed cell proliferation induced by a Rac GEF Tiam1. It has little effect on cell growth induced by a constitutively active Rac1 mutant. In addition, NSC23766 inhibited: (1) the anchorage-independent growth and invasion phenotypes of human prostate cancer PC-3 cells; (2) Rac activation and Rac-dependent aggregation of platelets stimulated by thrombin; and (3) Rac1 and Rac2 activities of hematopoietic stem/progenitor cells and induced their mobilization from mouse bone marrow to peripheral blood. Thus, NSC23766 is a lead small molecule inhibitor of Rac activity and could be useful for studying Rac-mediated cellular functions and for modulating pathological conditions in which Rac-deregulation may play a role.

Adenocarcinoma↗