Propofol-mediated circ_0000735 downregulation restrains tumor growth by decreasing integrin-ß1 expression in non-small cell lung cancer.

Propofol, an intravenous anesthetic agent, exerts an anti-tumor peculiarity in multifarious tumors. Circular RNA hsa_circ_0000735 (circ_0000735) is involved in non-small cell lung cancer (NSCLC) progression. The purpose of this study is to investigate whether propofol can curb NSCLC progression via regulating circ_0000735 expression. Cell viability, proliferation, apoptosis, and invasion were detected using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, 5-ethynyl-2'-deoxyuridine, flow cytometry, and transwell assays. Evaluation of protein levels was performed using western blotting or immunohistochemistry. Detection of circ_0000735 in tissue samples and cells was carried out using a real-time quantitative polymerase chain reaction. The molecular mechanisms associated with circ_0000735 were predicted by bioinformatics analysis and verified by dual-luciferase reporter assays. The relationship between propofol and circ_0000735 in vivo was verified by xenograft models. The results showed that circ_0000735 was overexpressed in NSCLC samples and cells. Propofol treatment overtly decreased circ_0000735 expression in NSCLC cells and repressed NSCLC cell viability, proliferation, invasion, and facilitated NSCLC cell apoptosis, but these effects mediated by propofol were counteracted by circ_0000735 overexpression. Circ_0000735 functioned as a miR-153-3p sponge and regulated integrin-ß1 (ITGB1) expression via adsorbing miR-153-3p. ITGB1 overexpression reversed circ_0000735 silencing-mediated effects on NSCLC cell viability, proliferation, invasion, and apoptosis. In conclusion, propofol restrained NSCLC growth by downregulating circ_0000735, which functioned as a miR-153-3p sponge and regulated ITGB1 expression via adsorbing miR-153-3p. This study provides evidence to support that propofol curbs NSCLC progression by regulating circRNA expression.

Therapeutic effect and mechanism of 4-phenyl butyric acid on renal ischemia-reperfusion injury in mice.

The aim of the present study was to explore the effects and possible mechanism of 4-phenylbutyric acid (4-PBA) on renal ischemia-reperfusion injury (RIRI) in mice. A RIRI model of HK-2 cells was constructed using hypoxia/reoxygenation (H/R) treatment. Dexmedetomidine and 4-PBA were used to treat the cells before and after modeling. Apoptosis and expression levels of cyclophilin D (CypD), cytochrome c, eukaryotic translation initiation factor 2α (eIF2α), glucose-regulated protein 78 (GRP78), intercellular adhesion molecule (ICAM)-1 and vascular adhesion molecule (VCAM)-1 were measured using flow cytometry, western blotting and immunohistochemistry. The renal volume, weight and renal arterial resistance index (RRI) were determined using the renal ischemia model. Compared with untreated model cells, 4-PBA treatment significantly decreased apoptosis and the expression levels of CypD, Cytochrome c, eIF2α and GRP78 in HK-2 cells. There was no significant change in renal volume and weight after modeling, but RRI was significantly decreased after 4-PBA treatments in the model. Western blotting and immunohistochemistry analysis demonstrated that 4-PBA treatment also significantly decreased the expression of ICAM-1 and VCAM-1. Overall, 4-PBA had a therapeutic effect on RIRI in mice. This protection may be mediated by decreasing the expression levels of CypD, Cytochrome c, eIF2α and GRP78, and subsequent reduction of cellular oxygen free radicals and apoptosis, leading to an alleviated endoplasmic reticulum stress response and RIRI.

Participation of Mind Bomb-2 in Sevoflurane Anesthesia Induces Cognitive Impairment in Aged Mice via Modulating Ferroptosis.

Postoperative cognitive dysfunction (POCD) is a complication of the central nervous system (CNS) often occurred after surgery or anesthesia in the elder patients. Mind bomb-2 (MIB2) has been reported to modulate neuronal functions. Here, we aimed to study whether MIB2 exerts roles in the effects of sevoflurane anesthesia on mice hippocampal neurons and function, and how. Aging male C57BL/6 mice were subjected to sevoflurane administration, and primary hippocampal neurons were adopted to study sevoflurane effects in vitro. Western blotting and immunohistochemistry assay were used to study the protein expression of MIB2. CCK-8 assay and propidium iodide (PI) staining were performed to evaluate cell viability and cell death, respectively. Ferroptosis-related indicators malondialdehyde (MDA), glutathione (GSH), and iron levels were checked through indicated ELISA kits. Co-immunoprecipitation was adopted to study the binding effects of MIB2 to GPX4. We found that sevoflurane anesthesia increased MIB2 expression in mice hippocampus tissues and neurons. Knockdown of MIB2 alleviated neuron death and ferroptosis induced by sevoflurane exposure. Downregulated MIB2 enhanced GPX4 stability and reduced its ubiquitination. MIB2 was verified to bind to GPX4. The effects of MIB2 knockdown on the neuron death and ferroptosis can be reversed by further siGPX4 transfection. In vivo results also showed that MIB2 knockdown reduced hippocampal neuron death, ferroptosis, and cognitive impairments in the sevoflurane-exposed mice. Taking all together, downregulation of MIB2 could alleviate the sevoflurane-anesthesia-induced cognitive dysfunction and neuron injury through reducing ferroptosis via GPX4. Our results also provide novel directions for POCD treatment using anti-MIB2-related drugs or strategies.

Effects of bilateral Pecto-intercostal Fascial Block for perioperative pain management in patients undergoing open cardiac surgery: a prospective randomized study.

BACKGROUND: Open cardiac surgical patients may experience severe acute poststernotomy pain. The ultrasound-guided Pecto-intercostal Fascial Block (PIFB) can cover anterior branches of intercostal nerves from T2 to T6. The aim of this study was to investigate the effect of bilateral PIFB in patients undergoing open cardiac surgery. METHODS: A group of 108 patients were randomly allocated to either receive bilateral PIFB (PIFB group) or no nerve block (SALI group). The primary endpoint was postoperative pain. The secondary outcome measures included intraoperative and postoperative sufentanil and parecoxib consumption, time to extubation, time to first feces, length of stay in the ICU and the length of hospital stay. Insulin, glucose, insulin resistance and interleukin (IL)-6 at 1, 2, 3 days after surgery were mearsured. The homeostasis model assessment (HOMA-IR) was used to measure perioperative insulin resistance. RESULTS: The PIFB group reported significantly less sufentanil and parecoxib consumption than the SALI group. Compared to the PIFB group, the SALI group had higher Numerical Rating Scale (NRS) pain scores at 24 h after operation both at rest and during coughing. The time to extubation, length of stay in the ICU and length of hospital stay were significantly decreased in the PIFB group compared with the SALI group. The PIFB group had a lower insulin, glucose, IL-6, HOMA-IR level than the SALI group 3 days after surgery. CONCLUSION: Bilateral PIFB provides effective analgesia and accelerates recovery in patients undergoing open cardiac surgery. TRIAL REGISTRATION: This study was registered in the Chinese Clinical Trial Registry ( ChiCTR 2000030609 ) on 08/03/2020.

Downregulation of HOTAIR reduces neuronal pyroptosis by targeting miR-455-3p/NLRP1 axis in propofol-treated neurons in vitro.

Propofol is one of the most common intravenous anesthetics which may cause neuronal cell death in young mice. HOX transcript antisense RNA (HOTAIR) was abnormally expressed in neurodegenerative diseases. However, the effect of HOTAIR on propofol-induced pyroptosis of neurons and related mechanisms are still unknown. In this study, propofol treatment significantly reduced neuronal the viability of neurons, and promoted the expression of inflammation-related factors. Propofol treatment also promoted neuron death and neuronal pyroptosis. All the above effects might be related to the propofol-induced overexpression of HOTAIR. Interestingly, knockdown of HOTAIR by shRNA (sh-HOTAIR) significantly inhibited neuronal pyroptosis, but increased neuronal viability. Further analysis showed that HOTAIR and Nod-like receptor protein1 (NLRP1) were the targets of miR-455-3p, respectively. Notably, propofol treatment decreased the level of miR-455-3p, while increased the level of NLRP1. In addition, sh-HOTAIR increased the level of miR-455-3p, which further inhibited the expression of NLRP1 and the activation of NLRP1 inflammasome, thereby inhibiting neuronal pyroptosis. More importantly, NLRP1 overexpression decreased neuronal viability, and reactivated NLRP1 inflammasome, thus reversing the inhibitory effect of sh-HOTAIR on pyroptosis. Our findings indicated that HOTAIR inhibited propofol-induced pyroptosis of neurons by regulating miR-455-3p/NLRP1 axis, indicating that HOTAIR may be a potential therapeutic target for propofol-induced neurotoxicity.

Acupoint Catgut Embedding Reduces Insulin Resistance in Diabetic Patients Undergoing Open Cardiac Surgery.

OBJECTIVE: Acupoint catgut embedding (ACE) has been used safely for thousands of years in traditional Chinese medicine. The aim of this study was to assess whether ACE can improve insulin resistance and promote rapid recovery after open cardiac surgery. METHODS: A group of 200 patients undergoing cardiac surgery were randomly allocated to receive either ACE (ACE group) or sham ACE (SHAM group). The primary outcome of our trial was insulin resistance assessed 1, 3, 5, and 7 days after surgery. The homeostasis model assessment (HOMA-IR) was used to measure perioperative insulin resistance. Secondary outcomes included insulin, glucose, and inflammatory cytokine (interleukin (IL) 6 and IL-8) levels; time to extubation; incidence of infection; time to first feces; acute kidney injury; incidence of postoperative nausea and vomiting (PONV); length of stay in the ICU; length of hospital stay; and other clinical parameters. RESULTS: The ACE group had lower insulin, glucose, IL-6, IL-8, and HOMA-IR levels than the SHAM group one week after the operation. The incidence of infection, incidence of PONV, time to drain removal, and length of hospital stay significantly were lower in the ACE group than in the SHAM group. CONCLUSION: ACE can improve insulin resistance and promote rapid recovery after open cardiac surgery.

Efficacy of Truncal Plane Blocks in Pediatric Patients Undergoing Subcutaneous Implantable Cardioverter-Defibrillator Placement.

OBJECTIVES: Pediatric patients undergoing subcutaneous implantable cardioverter-defibrillator (S-ICD) placement usually have substantial postoperative pain. The aim of this study was to investigate the effect of the transversus thoracic muscle plane (TTMP) block combined with serratus anterior plane block (SAPB) in patients undergoing S-ICD placement. DESIGN: A double-blind, randomized controlled study. SETTING: First Affiliated Hospital of Nanchang University. PARTICIPANTS: Patients aged nine-to-18 years undergoing S-ICD placement were included. INTERVENTIONS: A group of 102 patients randomly were allocated to either receive combined nerve blocks (NER group) or no nerve block (CON group). MEASUREMENTS AND MAIN RESULTS: The primary endpoint was perioperative fentanyl consumption. The secondary outcome measures included pain at rest and after movement at two, four, six, 12, 24, and 48 hours after extubation; 48-hour acetaminophen administration; time to extubation; length of stay in the postanesthesia care unit (PACU); length of hospital stay; codeine tablet consumption; and percentage of patients who had codeine tablets after discharge. The NER group reported significantly less intraoperative (4.1 µg/kg v 3.1 µg/kg, p = 0.04) and postoperative fentanyl consumption (3.8 µg/kg v 1.5 µg/kg, p = 0.006) than the CON group. Compared with the NER group, the CON group had higher Numerical Rating Scale (NRS) pain scores at 24 hours after surgery both at rest and after movement. The time to extubation (20.5 minutes v 12.6 minutes, p = 0.03) and length of stay in the PACU (30.5 minutes v 15.6 minutes, p = 0.02) were significantly decreased in the NER group compared with the CON group. The CON group had a significantly higher postoperative acetaminophen requirement than did the NER group (32 mg/kg v 16 mg/kg, p = 0.01). CONCLUSION: TTMP block combined with SAPB in pediatric S-ICD placement could provide effective analgesia.

Upregulation of miR-496 Rescues Propofol-induced Neurotoxicity by Targeting Rho Associated Coiled-coil Containing Protein Kinase 2 (ROCK2) in Prefrontal Cortical Neurons.

OBJECTIVE: Early exposure to general anesthesia in children might be a potentially highrisk factor for learning and behavioral disorders. The mechanism of neurotoxicity induced by general anesthesia was not defined. miR-496 could regulate cerebral injury, while the roles of miR- 496 in neurotoxicity were not elucidated. Therefore, we aimed to investigate the effects of miR- 496 in neurotoxicity induced by propofol. METHODS: Primary Prefrontal Cortical (PFC) neurons were isolated from neonatal rats and treated with propofol to induce neurotoxicity. Cell viability was detected by (3-(4,5-Dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and cell apoptosis was assessed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. The target relationship of miR-496 and Rho Associated Coiled-Coil Containing Protein Kinase 2 (ROCK2) was explored using luciferase assays. RESULTS: Propofol decreased cell viability, promoted cell apoptosis, and decreased the expression of miR-496 in PFC neurons in a dose-dependent manner. Overexpression of miR-496 attenuated neurotoxicity induced by propofol in PFC neurons. ROCK2 was a target of miR-496, and miR-496 oppositely modulated the expression of ROCK2. Besides, propofol increased the expression of ROCK2 through inhibiting miR-496 in PFC neurons. Overexpression of miR-496 attenuated propofol- induced neurotoxicity by targeting ROCK2 in PFC neurons. CONCLUSION: miR-496 was decreased in PFC neurons treated with propofol, and overexpression of miR-496 attenuated propofol-induced neurotoxicity by targeting ROCK2. miR-496 and ROCK2 may be promising targets for protecting propofol-induced neurotoxicity.

Efficacy of Bilateral Transversus Thoracis Muscle Plane Block in Pediatric Patients Undergoing Open Cardiac Surgery.

OBJECTIVES: Adequate pain management is crucial for pediatric patients undergoing open cardiac surgery. The aim of the present study was to investigate the effect of a bilateral transversus thoracis muscle plane (TTP) block on open cardiac surgery outcomes. SETTING: First Affiliated Hospital of Nanchang University. PARTICIPANTS: Patients ages 6 to 60 months undergoing cardiac surgical procedures were included. INTERVENTIONS: A group of 100 children were randomly allocated to receive either bilateral TTP block (TTP group) or no nerve block. MEASUREMENTS AND MAIN RESULTS: The primary endpoint was postoperative pain, which was measured with the Modified Objective Pain Score. The secondary outcome measures included intraoperative and postoperative fentanyl consumption; time to extubation; time to first feces; length of stay in the intensive care unit; length of hospital stay; and possible complications such as ropivacaine allergy, pneumothorax, hematomas, infections, and injuries to the internal mammary artery and vein. The TTP group had a significantly lower Modified Objective Pain Score until 24 hours after extubation than the no nerve block group. The TTP group reported significantly less fentanyl consumption. Time to extubation and lengths of stay in the intensive care unit and hospital were significantly decreased in the TTP group. CONCLUSION: Bilateral TTP blocks provide effective analgesia and accelerate recovery in pediatric patients.

Method for Dual Viral Vector Mediated CRISPR-Cas9 Gene Disruption in Primary Human Endothelial Cells.

Human endothelial cells (ECs) are widely used to study mechanisms of angiogenesis, inflammation, and endothelial permeability. Targeted gene disruption induced by Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-CRISPR-Associated Protein 9 (Cas9) nuclease gene editing is potentially an important tool for definitively establishing the functional roles of individual genes in ECs. We showed that co-delivery of adenovirus encoding EGFP-tagged Cas9 and lentivirus encoding a single guide RNA (sgRNA) in primary human lung microvascular ECs (HLMVECs) disrupted the expression of the Tie2 gene and protein. Tie2 disruption increased basal endothelial permeability and prevented permeability recovery following injury induced by the inflammatory stimulus thrombin. Thus, gene deletion via viral co-delivery of CRISPR-Cas9 in primary human ECs provides a novel platform to investigate signaling mechanisms of normal and perturbed EC function without the need for clonal expansion.

Role of the phagosomal redox-sensitive TRP channel TRPM2 in regulating bactericidal activity of macrophages.

Acidification of macrophage phagosomes serves an important bactericidal function. We show here that the redox-sensitive transient receptor potential (TRP) cation channel TRPM2 is expressed in the phagosomal membrane and regulates macrophage bactericidal activity through the activation of phagosomal acidification. Measurement of the TRPM2 current in phagosomes identified TRPM2 as a functional redox-sensitive cation channel localized in the phagosomal membrane. Simultaneous measurements of phagosomal Ca2+ changes and phagosome acidification in macrophages undergoing phagocytosis demonstrated that TRPM2 was required to mediate the efflux of cations and for phagosomal acidification during the process of phagosome maturation. Acidification in phagosomes was significantly reduced in macrophages isolated from Trpm2-/- mice as compared to wild type, and acidification was coupled to reduced bacterial clearance in Trpm2-/- mice. Trpm2+/+ macrophages treated with the vacuolar H+-ATPase inhibitor bafilomycin showed reduced bacterial clearance, similar to that in Trpm2-/- macrophages. Direct activation of TRPM2 using adenosine diphosphate ribose (ADPR) induced both phagosomal acidification and bacterial killing. These data collectively demonstrate that TRPM2 regulates phagosomal acidification, and is essential for the bacterial killing function of macrophages.

PAR1 Scaffolds TGFßRII to Downregulate TGF-ß Signaling and Activate ESC Differentiation to Endothelial Cells.

We studied the function of the G-protein-coupled receptor PAR1 in mediating the differentiation of mouse embryonic stem cells (mESCs) to endothelial cells (ECs) that are capable of inducing neovascularization. We observed that either deletion or activation of PAR1 suppressed mouse embryonic stem cell (mESC) differentiation to ECs and neovascularization in mice. This was mediated by induction of TGFßRII/TGFßRI interaction, forming an active complex, which in turn induced SMAD2 phosphorylation. Inhibition of TGF-ß signaling in PAR1-deficient mESCs restored the EC differentiation potential of mESCs. Thus, PAR1 in its inactive unligated state functions as a scaffold for TGFßRII to downregulate TGF-ß signaling, and thereby promote ESC transition to functional ECs. The PAR1 scaffold function in ESCs is an essential mechanism for dampening TGF-ß signaling and regulating ESC differentiation.

HIF2α signaling inhibits adherens junctional disruption in acute lung injury.

Vascular endothelial barrier dysfunction underlies diseases such as acute respiratory distress syndrome (ARDS), characterized by edema and inflammatory cell infiltration. The transcription factor HIF2α is highly expressed in vascular endothelial cells (ECs) and may regulate endothelial barrier function. Here, we analyzed promoter sequences of genes encoding proteins that regulate adherens junction (AJ) integrity and determined that vascular endothelial protein tyrosine phosphatase (VE-PTP) is a HIF2α target. HIF2α-induced VE-PTP expression enhanced dephosphorylation of VE-cadherin, which reduced VE-cadherin endocytosis and thereby augmented AJ integrity and endothelial barrier function. Mice harboring an EC-specific deletion of Hif2a exhibited decreased VE-PTP expression and increased VE-cadherin phosphorylation, resulting in defective AJs. Mice lacking HIF2α in ECs had increased lung vascular permeability and water content, both of which were further exacerbated by endotoxin-mediated injury. Treatment of these mice with Fg4497, a prolyl hydroxylase domain 2 (PHD2) inhibitor, activated HIF2α-mediated transcription in a hypoxia-independent manner. HIF2α activation increased VE-PTP expression, decreased VE-cadherin phosphorylation, promoted AJ integrity, and prevented the loss of endothelial barrier function. These findings demonstrate that HIF2α enhances endothelial barrier integrity, in part through VE-PTP expression and the resultant VE-cadherin dephosphorylation-mediated assembly of AJs. Moreover, activation of HIF2α/VE-PTP signaling via PHD2 inhibition has the potential to prevent the formation of leaky vessels and edema in inflammatory diseases such as ARDS.

Evidence of a common mechanism of disassembly of adherens junctions through Gα13 targeting of VE-cadherin.

The heterotrimeric G protein Gα13 transduces signals from G protein-coupled receptors (GPCRs) to induce cell spreading, differentiation, migration, and cell polarity. Here, we describe a novel GPCR-independent function of Gα13 in regulating the stability of endothelial cell adherens junctions (AJs). We observed that the oxidant H2O2, which is released in response to multiple proinflammatory mediators, induced the interaction of Gα13 with VE-cadherin. Gα13 binding to VE-cadherin in turn induced Src activation and VE-cadherin phosphorylation at Tyr 658, the p120-catenin binding site thought to be responsible for VE-cadherin internalization. Inhibition of Gα13-VE-cadherin interaction using an interfering peptide derived from the Gα13 binding motif on VE-cadherin abrogated the disruption of AJs in response to inflammatory mediators. These studies identify a unique role of Gα13 binding to VE-cadherin in mediating VE-cadherin internalization and endothelial barrier disruption and inflammation.

G protein subunit Galpha13 binds to integrin alphaIIbbeta3 and mediates integrin "outside-in" signaling.

Integrins mediate cell adhesion to the extracellular matrix and transmit signals within the cell that stimulate cell spreading, retraction, migration, and proliferation. The mechanism of integrin outside-in signaling has been unclear. We found that the heterotrimeric guanine nucleotide-binding protein (G protein) Galpha13 directly bound to the integrin beta3 cytoplasmic domain and that Galpha13-integrin interaction was promoted by ligand binding to the integrin alphaIIbbeta3 and by guanosine triphosphate (GTP) loading of Galpha13. Interference of Galpha13 expression or a myristoylated fragment of Galpha13 that inhibited interaction of alphaIIbbeta3 with Galpha13 diminished activation of protein kinase c-Src and stimulated the small guanosine triphosphatase RhoA, consequently inhibiting cell spreading and accelerating cell retraction. We conclude that integrins are noncanonical Galpha13-coupled receptors that provide a mechanism for dynamic regulation of RhoA.

A molecular switch that controls cell spreading and retraction.

Integrin-dependent cell spreading and retraction are required for cell adhesion, migration, and proliferation, and thus are important in thrombosis, wound repair, immunity, and cancer development. It remains unknown how integrin outside-in signaling induces and controls these two opposite processes. This study reveals that calpain cleavage of integrin beta(3) at Tyr(759) switches the functional outcome of integrin signaling from cell spreading to retraction. Expression of a calpain cleavage-resistant beta(3) mutant in Chinese hamster ovary cells causes defective clot retraction and RhoA-mediated retraction signaling but enhances cell spreading. Conversely, a calpain-cleaved form of beta(3) fails to mediate cell spreading, but inhibition of the RhoA signaling pathway corrects this defect. Importantly, the calpain-cleaved beta(3) fails to bind c-Src, which is required for integrin-induced cell spreading, and this requirement of beta(3)-associated c-Src results from its inhibition of RhoA-dependent contractile signals. Thus, calpain cleavage of beta(3) at Tyr(759) relieves c-Src-mediated RhoA inhibition, activating the RhoA pathway that confines cell spreading and causes cell retraction.

Identification of differentially expressed genes in omental adipose tissues of obese patients by suppression subtractive hybridization.

To identify differentially expressed genes between obese individuals and normal control, we have undertaken suppression subtractive hybridization (SSH). Omental adipose tissues were obtained via abdominal surgery for appendicitis in both 13 obese subjects [BMI (body mass index) >30 kg/m2] and 13 normal subjects (BMI >18 and <25 kg/m2). Following SSH, about one thousand clones were sequenced and found to derive from 426 different genes. These predominately expressed genes included genes involved in lipid metabolism, cytokines, signal transduction, GLUT4 translocation, cell cycle and growth, cytoskeleton, and others. Although more detailed analyses are necessary, it is anticipated that further study of genes identified will provide insights into their specific roles in the etiology of obesity.

A resistin binding peptide selected by phage display inhibits 3T3-L1 preadipocyte differentiation.

BACKGROUND: Resistin, a newly discovered cysteine-rich hormone secreted mainly by adipose tissues, has been proposed to form a biochemical link between obesity and type 2 diabetes. However, the resistin receptor has not yet been identified. This study aimed to identify resistin binding proteins/receptor. METHODS: Three cDNA fragments with the same 11 bp 5' sequence were found by screening a cDNA phage display library of rat multiple tissues. As the reading frames of the same 11 bp 5' sequence were interrupted by a TGA stop codon, plaque lift assay was consequently used to prove the readthrough phenomenon. The stop codon in the same 11 bp 5' sequence was replaced by tryptophan, and the binding activity of the coded peptide [AWIL, which was designated as resistin binding peptide (RBP)] with resistin was identified by the confocal microscopy technique and the affinity chromatography experiment. pDual GC-resistin and pDual GC-resistin binding peptide were co-transfected into 3T3-L1 cells to confirm the function of resistin binding peptide. RESULTS: Three cDNA fragments with the same 11 bp 5' sequence were found. The TGA stop codon in reading frames of the same 11 bp 5' sequence was proved to be readthroughed. The binding activity of RBP with resistin was consequently identified. The expression of the resistin binding peptide in 3T3-L1 preadipocytes expressing pDual GC-resistin significantly inhibited the adipogenic differentiation. CONCLUSION: RBP could effectively rescue the promoted differentiation of resistin overexpressed 3T3-L1 preadipocyte.

A mutation in signal peptide of rat resistin gene inhibits differentiation of 3T3-L1 preadipocytes.

AIM: To detect the resistin expression of white adipose tissue in diet-induced obese (DIO) versus diet-resistant (DR) rats, and to investigate the relationship of mutated resistin and 3T3-L1 preadipocytes differentiation. METHODS: RT-PCR and Western Blot were used to detect gene /protein expression. 3T3-L1 cells were cultured, transfected, and induced to differentiation using 0.5 mmol/L 3-isobutyl-1-methylxanthine (MIX), 1 mg/L insulin, and 1 micromol/L dexamethasone. Oil red O staining was applied to detect the degree of preadipocytes differentiation. RESULTS: Expression of resistin mRNA was upregulated in DIO rats and downregulated in DR rats. However, the expression levels varied greatly within the groups. Sequencing of the resistin genes from DIO and DR rats revealed a Leu9Val (C25G) missense mutation within the signal peptide in one DR rat. The mutant resistin inhibited preadipocyte differentiation. Local experiments and Western blotting with tagged resistin fusion proteins identified both mutant and wild type proteins in the cytoplasm and secreted into the culture medium. Computer predictions using the Proscan and Subloc programs revealed four putative phosphorylation sites and a possible leucine zipper motif within the rat resistin protein. CONCLUSION: Resistin-increased differentiation may be inhibited by the mutation-containing precursor protein, or by the mutant non-secretory resistin isoform.