Biology subjects

Chen, R.

Publications and source records attributed to Chen, R..

At least 307 records · Page 17Linked to original sources

bioRxiv2021

Retinal organoids derived from rhesus macaque iPSCs undergo accelerated differentiation compared to human stem cells

PurposeTo compare the timing and efficiency of the development of non-human primate (NHP) derived retinal organoids in comparison to those derived from human embryonic stem cells. MethodsHuman embryonic stem cells (hESCs) and induced-pluripotent stem cells (rhiPSCs) derived from non-human primates (Macaca mulatta) were differentiated into retinal organoids by using an established differentiation protocol. Briefly, embryoid bodies were formed from pluripotent stem cells and induced into a neural lineage with neural induction media with the addition of BMP4. Thereafter, self-formation of optic vesicles was allowed to form in a 2D culture in retinal differentiation media (RDM). Optic vesicles were then manually harvested and cultured in suspension in 3D-RDM media until analysis. Differences in the timing of differentiation and efficiency of retinal organoid development were assessed by light microscopy, electron microscopy, immunocytochemistry, and single-cell transcriptomics. ResultsGeneration of retinal organoids was achieved from both human and several NHP pluripotent stem cells lines. All rhiPSC lines resulted in retinal differentiation with the formation of optic vesicle-like structures similar to what has been observed in hESC retinal organoids. NHP retinal organoids had laminated structure and were composed of mature retinal cell types including cone and rod photoreceptors. Single cell RNA sequencing was conducted at two time points, which allowed identification of cell types and characterization of developmental trajectory in the developing organoid. Important differences between rhesus and human cells were measured regarding the timing and efficiency of retinal organoid differentiation. While the culture of NHP-derived iPSCs is relatively difficult compared to human stem cells, the generation of retinal organoids is feasible and may be less time consuming due to an intrinsically faster timing of retinal differentiation. ConclusionsRetinal organoids produced from iPSCs derived from Rhesus monkey using established protocols differentiate through the stages of organoid development faster than those derived from human stem cells. The production of NHP retinal organoids may be advantageous to reduce experimental time and cost for basic biology studies in retinogenesis as well as for preclinical trials in NHPs studying retinal allograft transplantation.

cell biology↗

bioRxiv2021

Validated machine learning algorithm with sub-clonal sensitivity reveals widespread pan-cancer human leukocyte antigen loss of heterozygosity

Human leukocyte antigen loss of heterozygosity (HLA LOH) allows cancer cells to escape immune recognition by deleting HLA alleles, causing the suppressed presentation of tumor neoantigens that would otherwise bind to them. Despite its importance in immunotherapy response, few methods exist to detect HLA LOH, and their accuracy is not well understood. Here, we develop DASH (Deletion of Allele-Specific HLAs), a novel machine learning-based algorithm to detect HLA LOH from paired tumor-normal sequencing data. Through validation with cell line mixtures and patient-specific digital PCR, we demonstrate increased sensitivity compared to previously published tools and pave the way for clinical utility. Using DASH on 611 patients across 15 tumor types, we found that 18% of patients had HLA LOH. Moreover, we show inflated HLA LOH rates compared to genome-wide LOH and correlations between CD274 (PD-L1) expression and MSI status, suggesting the HLA LOH is a key immune resistance strategy.

bioinformatics↗

bioRxiv2021

CD147 antibody specifically and effectively inhibits infection and cytokine storm of SARS-CoV-2 variants

SARS-CoV-2 and its variants are raging worldwide. Unfortunately, the global vaccination is not efficient enough to attain a vaccine-based herd-immunity and yet no special and effective drug is developed to contain the spread of the disease. Previously we have identified CD147 as a novel receptor for SARS-CoV-2 infection. Here, we demonstrated that CD147 antibody effectively inhibits infection and cytokine storm caused by SARS-CoV-2 variants. In CD147KO VeroE6 cells, infections of SARS-CoV-2, its variants (B.1.1.7, B.1.351) and pseudovirus mutants (B.1.1.7, B.1.351, B.1.525, B.1.526 (S477N), B.1.526 (E484K), P.1, P.2, B.1.617.1, B.1.617.2) were decreased. Meanwhile, CD147 antibody effectively blocked the entry of variants and pseudomutants in VeroE6 cells, and inhibited the expression of cytokines. A model of SARS-CoV-2-infected hCD147 transgenic mice was constructed, which recapitulated the features of exudative diffuse alveolar damage and dynamic immune responses of COVID-19. CD147 antibody could effectively clear the virus and alveolar exudation, resolving the pneumonia. We found the elevated level of cyclophilin A (CyPA) in plasma of severe/critical cases, and identified CyPA as the most important proinflammatory intermediate causing cytokine storm. Mechanistically, spike protein of SARS-CoV-2 bound to CD147 and initiated the JAK-STAT pathway, which induced expression of CyPA. CyPA reciprocally bound to CD147, triggered MAPK pathway and consequently mediated the expression of cytokine and chemokine. In conclusion, CD147 is a critical target for SARS-CoV-2 variants and CD147 antibody is a promising drug to control the new wave of COVID-19 epidemic.

immunology↗

bioRxiv2021

Single-molecule mechanical unfolding kinetics of unmodified Saccharomyces cerevisiae tRNAPhe: a hint to the tRNA chaperone-tRNA interaction mechanism

The biological activity of tRNA is closely related to its mechanical folding properties. Although previous studies focused on the folding and unfolding mechanism of tRNA, its kinetics are largely unknown. In this study, combining optical tweezers and molecule dynamics simulations, we characterized the mechanical folding and unfolding processes of a single unmodified Saccharomyces cerevisiae tRNAphe. We identified the intermediates and pathways for tRNA mechanical folding and unfolding in the presence of Mg2+, discovering that the folding/unfolding kinetics of D stem-loop and T stem-loop but not the anti-codon stem-loop significantly affected by their upstream and downstream structures. The cooperative unfolding of the tRNA in the presence of Mg2+ lead to a large hysteresis between the folding and unfolding pathway, and such hysteresis and unfolding cooperativity are significantly reduced by lowering the Mg2+ concentration or mutating the nucleotides forming the elbow structure. Moreover, both steered molecular dynamics simulation and optical tweezers experiment results support that, formation of tertiary interactions in the elbow region increases energy barriers of the mechanical unfolding pathway, including those in between intermediates, and determines the overall unfolding cooperativity. Our studies may shed light on the detailed tRNA chaperone mechanism of TruB and TrmA.

biophysics↗

bioRxiv2021

Precision neoantigen discovery using large-scale immunopeptidomes and composite modeling of MHC peptide presentation

Major histocompatibility complex (MHC)-bound peptides that originate from tumor-specific genetic alterations, known as neoantigens, are an important class of anti-cancer therapeutic targets. Accurately predicting peptide presentation by MHC complexes is a key aspect of discovering therapeutically relevant neoantigens. Technological improvements in mass-spectrometry-based immunopeptidomics and advanced modeling techniques have vastly improved MHC presentation prediction over the past two decades. However, improvement in the sensitivity and specificity of prediction algorithms is needed for clinical applications such as the development of personalized cancer vaccines, the discovery of biomarkers for response to checkpoint blockade and the quantification of autoimmune risk in gene therapies. Toward this end, we generated allele-specific immunopeptidomics data using 25 mono-allelic cell lines and created Systematic HLA Epitope Ranking Pan Algorithm (SHERPA), a pan-allelic MHC-peptide algorithm for predicting MHC-peptide binding and presentation. In contrast to previously published large-scale mono-allelic data, we used an HLA-null K562 parental cell line and a stable transfection of HLA alleles to better emulate native presentation. Our dataset includes five previously unprofiled alleles that expand MHC binding pocket diversity in the training data and extend allelic coverage in underprofiled populations. To improve generalizability, SHERPA systematically integrates 128 mono-allelic and 384 multi-allelic samples with publicly available immunoproteomics data and binding assay data. Using this dataset, we developed two features that empirically estimate the propensities of genes and specific regions within gene bodies to engender immunopeptides to represent antigen processing. Using a composite model constructed with gradient boosting decision trees, multiallelic deconvolution and 2.15 million peptides encompassing 167 alleles, we achieved a 1.44 fold improvement of positive predictive value compared to existing tools when evaluated on independent mono-allelic datasets and a 1.15 fold improvement when evaluating on tumor samples. With a high degree of accuracy, SHERPA has the potential to enable precision neoantigen discovery for future clinical applications.

bioinformatics↗

bioRxiv2021

SmProt: a reliable repository with comprehensive annotation of small proteins identified from ribosome profiling

Small proteins specifically refer to proteins consisting of less than 100 amino acids translated from small open reading frames (sORFs), which were usually missed in previous genome annotation. The significance of small proteins has been revealed in current years, along with the discovery of their diverse functions. However, systematic annotation of small proteins is still insufficient. SmProt was specially developed to provide valuable information on small proteins for scientific community. Here we present the update of SmProt, which emphasizes reliability of translated sORFs, genetic variants in translated sORFs, disease-specific sORFs translation events or sequences, and significantly increased data volume. More components such as non-AUG translation initiation, function, and new sources are also included. SmProt incorporated 638,958 unique small proteins curated from 3,165,229 primary records, which were computationally predicted from 419 ribosome profiling (Ribo-seq) datasets and collected from the literature and other sources originating from 370 cell lines or tissues in 8 species (Homo sapiens, Mus musculus, Rattus norvegicus, Drosophila melanogaster, Danio rerio, Saccharomyces cerevisiae, Caenorhabditis elegans, and Escherichia coli). In addition, small protein families identified from human microbiomes were collected. All datasets in SmProt are free to access, and available for browse, search, and bulk downloads at http://bigdata.ibp.ac.cn/SmProt/.

bioinformatics↗

bioRxiv2021

AIE nanoparticles camouflaged with tumor cell-derived exosomes for NIR-II imaging-guided photothermal therapy

Nanoparticles (NPs) assisted photothermal therapy (PTT) is a promising cancer treatment modality and has attracted the attention of the scientific mainstream. However, developing NPs that exhibit efficient optical properties and specific tumor targeting capability simultaneously is difficult. Herein, we develop hybrid nanovesicles consisting of tumor cell-derived exosomes (EXO) and organic aggregation-induced emission (AIE) nanoparticles (TT3-oCB NP@EXOs) with enhanced second near-infrared (NIR-II, 900-1700 nm) fluorescence property and PTT functionality. Compared with TT3-oCB NPs, TT3-oCB NP@EXOs exhibit excellent biocompatibility, specific targeting ability in vitro, homing to homologous tumors in vivo, and prolonged circulation time. Furthermore, TT3-oCB NP@EXOs were utilized as biomimetic NPs for NIR-II fluorescence imaging-guided PTT of tumors, due to their high and stable photothermal conversion capacity under 808 nm irradiation. Therefore, the tumor cell-derived EXO/AIE NP hybrid nanovesicles may provide an alternative artificial targeting strategy for improving tumor diagnosis and PTT.

bioengineering↗

bioRxiv2021

Cytostatic hypothermia and its impact on glioblastoma and survival

Novel therapeutic approaches are needed for patients with glioblastoma (GBM) who otherwise have limited options. Here we studied and deployed non-freezing cytostatic hypothermia to stunt GBM growth. This contrasts with ablative, cryogenic hypothermia: a double-edged sword against tumors infiltrating otherwise healthy tissue. We investigated three grades of hypothermia in vitro and identified a cytostatic window of 20-25{degrees}C. For some glioma lines, 18 h/d of cytostatic hypothermia was sufficient to halt division in vitro. Cytostatic hypothermia induced cell cycle arrest, reduced metabolite production and consumption, and reduced inflammatory cytokine synthesis. Next, we fabricated an experimental device to test local cytostatic hypothermia in vivo in two rodent models of GBM: utilizing the rat F98 and the human U-87 MG lines. Hypothermia more than doubled the median survival of F98 bearing rats from 3.9 weeks to 9.7 weeks and two rats survived through 12 weeks. All U-87 MG bearing rats that successfully received cytostatic hypothermia survived their study period. Thus, this approach lengthened survival without chemical interventions. Unlike targeted therapeutics that are successful in preclinical models but fail in clinical trials, cytostatic hypothermia affects multiple cellular processes simultaneously. This, alongside reduced cellular division, suggests that opportunities for tumor evolution are reduced and the likelihood of translation to larger species may be more likely. In addition, based on our work, designs, and the literature, engineering a patient-centric device is tangible. Taken together, cytostatic hypothermia could be a novel approach to cancer therapy and eventually serve a valuable role to patients with GBM. One Sentence SummaryHypothermia influences multiple cellular pathways, can be a safe and effective approach to halt glioblastoma growth, and holds translational promise.

bioengineering↗

bioRxiv2021

SMARCA4 regulates spatially restricted metabolic plasticity in 3D multicellular tissue

SWI/SNF and related chromatin remodeling complexes act as tissue-specific tumor suppressors and are frequently inactivated in different cancers. Although many regulatory activities of SWI/SNF have been identified using 2D cell culture, the effects of SWI/SNF alterations in more complex 3D tissues have remained poorly understood. Here we employed 3D cell culture conditions that yield transcriptomic states mirroring primary lung adenocarcinoma (LUAD) specimens better than 2D culture. By analyzing spatial patterns of gene expression and DNA accessibility in 3D spheroids using single-cell RNA-seq and ATAC-seq, we find that the SWI/SNF ATPase SMARCA4 (BRG1) induces state-specific changes to DNA accessibility that influence spatially heterogeneous expression patterns and metabolism. In 3D conditions, SMARCA4 promotes accessibility for AP-1 transcription factors, including ATF3, a regulator of metabolism and repressor of NRF2 antioxidant signaling. These changes reduce expression of SLC7A11 in a distinct portion of cells, which sensitizes A549 spheroids to cell death via ferroptosis under oxidizing conditions. Consistent with these results, we find that SMARCA4 alterations are associated with derepression of NRF2 targets in human tumors independently of NRF2/KEAP1 status. Our work reveals new 3D-specific features and unanticipated spatial complexity associated with chromatin remodeling in multicellular tissues.

systems biology↗

bioRxiv2021

Evolutionary Analysis of Transcriptional Regulation Mediated by Cdx2 in Rodents

Differences in gene expression, which can arise from divergence in cis-regulatory elements or alterations in transcription factors binding specificity, are one of the most important causes of phenotypic diversity during evolution. By protein sequence analysis, we observed high sequence conservation in the DNA binding domain (DBD) of the transcription factor Cdx2 across many vertebrates, whereas three amino acid changes were exclusively found in mouse Cdx2 (mCdx2), suggesting potential positive selection in the mouse lineage. Multi-omics analyses were then carried out to investigate the effects of these changes. Surprisingly, there were no significant functional differences between mCdx2 and its rat homologue (rCdx2), and none of the three amino acid changes had any impact on its function. Finally, we used rat-mouse allodiploid embryonic stem cells (RMES) to study the cis effects of Cdx2-mediated gene regulation between the two rodents. Interestingly, whereas Cdx2 binding is largely divergent between mouse and rat, the transcriptional effect induced by Cdx2 is conserved to a much larger extent. Author summaryOur study 1) represented a first systematic analysis of species-specific adaptation in DNA binding pattern of transcription factor. Although the mouse-specific amino acid changes did not manifest functional impact in our system, several explanations may account for it (See Discussion part for the detail); 2) represented a first study of cis-regulation between two reproductively isolated species by using a novel allodiploid system; 3) demonstrated a higher conservation of transcriptional output than that of DNA binding, suggesting the evolvability/plasticity of the latter; 4) finally provided a rich data resource for Cdx2 mediated regulation, including gene expression, chromatin accessibility and DNA binding etc.

evolutionary biology↗

bioRxiv2021

Competitive coordination of the dual roles of the Hedgehog co-receptor in homophilic adhesion and signal reception

Hedgehog (Hh) signaling patterns embryonic tissues and contributes to homeostasis in adults. In Drosophila, Hh transport and signaling are thought to occur along a specialized class of actin-rich filopodia, termed cytonemes. Here, we report that Interference hedgehog (Ihog) not only forms a Hh receptor complex with Patched to mediate intracellular signaling, but Ihog also engages in trans-homophilic binding leading to cytoneme stabilization in a manner independent of its role as the Hh receptor. Both functions of Ihog (trans-homophilic binding for cytoneme stabilization and Hh binding for ligand sensing) involve a region of the first fibronectin repeat of the extracellular domain. Thus, the Ihog-Ihog interaction and the Hh-Ihog interaction cannot occur simultaneously for a single Ihog molecule. By combining experimental data and mathematical modeling, we determined that Hh-Ihog heterophilic interaction dominates and Hh can disrupt and displace Ihog molecules involved in trans-homophilic binding. Consequently, we proposed that the weaker Ihog-Ihog trans interaction promotes and stabilizes direct membrane contacts along cytonemes and that, as the cytoneme encounters secreted Hh ligands, the ligands trigger release of Ihog from trans Ihog-Ihog complex enabling transport or internalization of the Hh ligand-Ihog-Patched -receptor complex. Thus, the seemingly incompatible functions of Ihog in homophilic adhesion and ligand binding cooperate to assist Hh transport and reception along the cytonemes. One-sentence summaryApparently incompatible functions of Ihog in homophilic adhesion and ligand binding cooperate in Hh transport and reception.

bioinformatics↗

bioRxiv2021

Hydroxide ions amplified by water entanglement underly the mechanism of general anesthesia

It is believed that inhaled anesthetics occupy hydrophobic pockets within target proteins, but how inhaled anesthetics with diverse shapes and sizes fit into highly structurally selective pockets is unknown. For hydroxide ions are hydrophobic, we determined whether hydroxide ions could bridge inhaled anesthetics and protein pockets. We found that small additional load of cerebral hydroxide ions decreases anesthetic potency. Multiple-water entanglement network, derived from Ising model, has a great ability to amplify ultralow changes in the cerebral hydroxide ion concentration, and consequently, amplified hydroxide ions account for neural excitability. Molecular dynamics simulations showed that inhaled anesthetics produce anesthesia by attenuating the formation of multiple-water entanglement network. This work suggests amplified hydroxide ions underlying a unified mechanism for the anesthetic action of inhaled anesthetics.

animal behavior and cognition↗

bioRxiv2021

Genetic and structural basis for recognition of SARS-CoV-2 spike protein by a two-antibody cocktail

The SARS-CoV-2 pandemic has led to an urgent need to understand the molecular basis for immune recognition of SARS-CoV-2 spike (S) glycoprotein antigenic sites. To define the genetic and structural basis for SARS-CoV-2 neutralization, we determined the structures of two human monoclonal antibodies COV2-2196 and COV2-21301, which form the basis of the investigational antibody cocktail AZD7442, in complex with the receptor binding domain (RBD) of SARS-CoV-2. COV2-2196 forms an "aromatic cage" at the heavy/light chain interface using germline-encoded residues in complementarity determining regions (CDRs) 2 and 3 of the heavy chain and CDRs 1 and 3 of the light chain. These structural features explain why highly similar antibodies (public clonotypes) have been isolated from multiple individuals1-4. The structure of COV2-2130 reveals that an unusually long LCDR1 and HCDR3 make interactions with the opposite face of the RBD from that of COV2-2196. Using deep mutational scanning and neutralization escape selection experiments, we comprehensively mapped the critical residues of both antibodies and identified positions of concern for possible viral escape. Nonetheless, both COV2-2196 and COV2-2130 showed strong neutralizing activity against SARS-CoV-2 strain with recent variations of concern including E484K, N501Y, and D614G substitutions. These studies reveal germline-encoded antibody features enabling recognition of the RBD and demonstrate the activity of a cocktail like AZD7442 in preventing escape from emerging variant viruses.

immunology↗

bioRxiv2021

P4HA2-induced prolyl hydroxylation suppresses YAP1-mediated prostate cancer cell migration, invasion, and metastasis

Yes-associated protein 1 (YAP1), a key player in the Hippo pathway, has been shown to play a critical role in tumor progression. However, the role of YAP1 in prostate cancer cell invasion, migration, and metastasis is not well defined. Through functional, transcriptomic, epigenomic, and proteomic analyses, we showed that prolyl hydroxylation of YAP1 plays a critical role in the suppression of cell migration, invasion, and metastasis in prostate cancer. Knockdown (KD) or knockout (KO) of YAP1 led to an increase in cell migration, invasion, and metastasis in prostate cancer cells. Microarray analysis showed that the EMT pathway was activated in Yap1-KD cells. ChIP-seq analysis showed that YAP1 target genes are enriched in pathways regulating cell migration. Mass spectrometry analysis identified P4H prolyl hydroxylase in the YAP1 complex and YAP1 was hydroxylated at multiple proline residues. Proline-to-alanine mutations of YAP1 isoform 3 identified proline 174 as a critical residue, and its hydroxylation suppressed cell migration, invasion, and metastasis. KO of P4ha2 led to an increase in cell migration and invasion, which was reversed upon Yap1 KD. Our study identified a novel regulatory mechanism of YAP1 by which P4HA2-dependent prolyl hydroxylation of YAP1 determines its transcriptional activities and its function in prostate cancer metastasis.

cancer biology↗

bioRxiv2021

Decoding the single-cell landscape and intercellular crosstalk in the transplanted liver: a 4-dimension mouse model

Graft remodeling after transplantation maintains graft functionality and determines graft survival. However, a comprehensive understanding of cellular diversity and interplay during graft remodeling remains to be fully characterized. In this study, we established a well tolerant C57BL/6 to C57BL/6 orthotopic liver transplantation (LT) mice model and observed two stages of graft recovery including an acute phase and a steady phase. We next performed single-cell RNA sequencing (scRNA-seq) and cytometry by time-of-flight (CyTOF) and recorded the cellular hierarchy in the transplanted liver during the two stages. Besides the dynamic change of cell proportion, it was notable that recipient-derived cells took over the transplanted liver in most cell types (e.g., B cells, T cells, dendritic cells, granulocytes and monocytes) except CD206+ MerTK+ macrophages and CD161+ CD49a+ CD49b-natural killer cells. We then focused on macrophages and captured 5 distinct transcriptional signatures to define novel subclusters. Using a ligand-receptor interaction strategy, we identified specific macrophage-hepatocyte interactions during the acute and stable phases, causing metabolic remodeling in the transplanted liver. Our results delineated a 4-dimension cell atlas (type-proportion-source-time) of the transplanted liver, which sheds light on the physiological process of liver graft maintenance and graft-recipient crosstalk.

immunology↗

bioRxiv2020

Quantitative Control of Noise in Mammalian Gene Expression by Dynamic Histone Regulations

Fluctuation ( noise) in gene expression is critical for mammalian cellular processes. Numerous mechanisms contribute to its origins, yet large noises induced by single transcriptional activator species remain to be experimentally understood. Here, we combined the dynamic regulation of transcriptional activator binding, histone regulator inhibitors, and single-cell quantification of chromatin accessibility, mRNA, and protein to probe putative mechanisms. Using a light-induced expression system, we show that the transcriptional activator forms a positive feedback loop with histone acetyltransferases CBP/p300. It generates epigenetic bistability in H3K27ac, which contributes to large noise. Disable of the positive feedback loop by CBP/p300 and HDAC4/5 inhibitors also reduces heterogeneity in endogenous genes, suggesting a universal mechanism. We showed that the noise was reduced by pulse-wide modulation of transcriptional activator binding due to alternating the system between high and low monostable states. Our findings could provide a mechanism-based approach to modulate noise in synthetic and endogenous gene expressions.

molecular biology↗

bioRxiv2020

Sterilizing immunity against SARS-CoV-2 in hamsters conferred by a novel recombinant subunit vaccine

A safe and effective SARS-CoV-2 vaccine is essential to avert the on-going COVID-19 pandemic. Here, we developed a subunit vaccine, which is comprised of CHO-expressed spike ectodomain protein (StriFK) and nitrogen bisphosphonates-modified zinc-aluminum hybrid adjuvant (FH002C). This vaccine candidate rapidly elicited the robust humoral response, Th1/Th2 balanced helper CD4 T cell and CD8 T cell immune response in animal models. In mice, hamsters, and non-human primates, 2-shot and 3-shot immunization of StriFK-FH002C generated 28- to 38-fold and 47- to 269-fold higher neutralizing antibody titers than the human COVID-19 convalescent plasmas, respectively. More importantly, the StriFK-FH002C immunization conferred sterilizing immunity to prevent SARS-CoV-2 infection and transmission, which also protected animals from virus-induced weight loss, COVID-19-like symptoms, and pneumonia in hamsters. Vaccine-induced neutralizing and cell-based receptor-blocking antibody titers correlated well with protective efficacy in hamsters, suggesting vaccine-elicited protection is immune-associated. The StriFK-FH002C provided a promising SARS-CoV-2 vaccine candidate for further clinical evaluation.

microbiology↗

bioRxiv2020

Oxidized LDL but not angiotensin II induces the interaction between LOX-1 and AT1 receptors

Oxidized low-density lipoprotein (Ox-LDL) can induce cardiac hypertrophy, but the mechanism is still unclear. Here we elucidate the role of angiotensin II (AngII) receptor (AT1-R) in Ox-LDL-induced cardiomycyte hypertrophy. Inhibition of Ox-LDL receptor LOX-1 and AT1-R rather than AngII abolished Ox-LDL-induced hypertrophic responses. Similar results were obtained from the heart of mice lacking endogenous Ang II and their cardiomyocytes. Ox-LDL but not AngII induced binding of LOX-1 to AT1-R, and the inhibition of LOX-1 or AT1-R rather than AngII abolished the association of these two receptors. Ox-LDL-induced ERKs phosphorylation in LOX-1 and AT1-R-overexpression cells and the binding of both receptors were suppressed by the mutants of LOX-1 (Lys266Ala/Lys267Ala) or AT1-R (Glu257Ala), however, the AT1-R mutant lacking Gq protein-coupling ability only abolished the ERKs phosphorylation. The phosphorylation of ERKs induced by Ox-LDL in LOX-1 and AT1-R-overexpression cells was abrogated by Gq protein inhibitor but not by Jak2, Rac1 and RhoA inhibitors. Therefore, the direct interaction between LOX-1 and AT1-R and the downstream Gq protein activation are important mechanisms for Ox-LDL-but not AngII-induced cardiomyocyte hypertrophy.

cell biology↗