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1.
BMC Med Ethics ; 23(1): 105, 2022 11 01.
Article in English | MEDLINE | ID: mdl-36319979

ABSTRACT

BACKGROUND: Residual dried blood spots (rDBS) from newborn screening programmes represent a valuable resource for medical research, from basic sciences, through clinical to public health. In Hong Kong, there is no legislation for biobanking. Parents' view on the retention and use of residual newborn blood samples could be cultural-specific and is important to consider for biobanking of rDBS. OBJECTIVE: To study the views and concerns on long-term storage and secondary use of rDBS from newborn screening programmes among Hong Kong Chinese parents. METHODS: A mixed-method approach was used to study the views and concerns on long-term storage and secondary use of rDBS from newborn screening programmes among Hong Kong Chinese parents of children 0-3 years or expecting parents through focus groups (8 groups; 33 participants) and a survey (n = 1012, 85% mothers) designed with insights obtained from the focus groups. We used framework analysis to summarise the themes as supportive factors, concerns and critical arguments for retention and secondary use of rDBS from focus group discussion. We used multiple logistic regression to assess factors associated with support for retention and secondary use of rDBS in the survey. RESULTS: Both in focus groups and survey, majority of parents were not aware of the potential secondary use of rDBS. Overall secondary use of rDBS in medical research was well accepted by a large proportion of Hong Kong parents, even if all potential future research could not be specified in a broad consent. However parents were concerned about potential risks of biobanking rDBS including leaking of data and mis-use of genetic information. Parents wanted to be asked for permission before rDBS are stored and mainly did not accept an "opt-out" approach. The survey showed that parents born in mainland China, compared to Hong Kong born parents, had lower awareness of newborn screening but higher support in biobanking rDBS. Higher education was associated with support in rDBS biobanking only among fathers. CONCLUSION: Long-term storage and secondary use of rDBS from newborn screening for biomedical research and a broad consent for biobanking of rDBS are generally acceptable to Hong Kong parents given their autonomy is respected and their privacy is protected, highlighting the importance of an accountable governance and a transparent access policy for rDBS biobanks.


Subject(s)
Biological Specimen Banks , Neonatal Screening , Infant, Newborn , Child , Female , Humans , Neonatal Screening/methods , Hong Kong , Parents , Mothers
2.
Zhonghua Xue Ye Xue Za Zhi ; 42(9): 747-751, 2021 Sep 14.
Article in Chinese | MEDLINE | ID: mdl-34753229

ABSTRACT

Objective: To evaluate the effects of glucocorticoids (dexamethasone and methylprednisolone) on the proliferation of CD19 Chimeric antigen receptor (CAR) modified T cells in vitro. Methods: Peripheral blood mononuclear cells from healthy volunteers were collected as T cells. CD19 CAR-T cells were prepared by CD3 magnetic beads sorting and CD19 CAR lentivirus transfection. The transfection rates and the proportion of CD19 CAR-T cells in the culture system were analyzed using a flow cytometer. The mean fluorescence intensity (MFI) of CD19 CAR-T cells was measured after staining with Carboxyfluorescein diacetate succinimidyl ester cell proliferation tracer fluorescent probe, Lactate dehydrogenase (LDH) cytotoxicity assay was used to detect the effects of different concentrations of glucocorticoid on the killing activity of B-cell tumor cell lines. Results: In this study, the CD19 CAR transfection rate of CD19 CAR-T cells was (51.34±5.28) %. The killing activities of different doses of methylprednisolone on Nalm6, Pfeiffer, and U2932 tumor cells were higher than that of dexamethasone at 24 h. The killing activities of 4 mg/mL methylprednisolone on Nalm6, Pfeiffer, and U2932 were higher than that of 0.75 mg/ml group, while the killing activity of 12 mg/ml methylprednisolone was lower than that of 2.25 mg/ml dexamethasone at 48 h. However, the killing activities of different doses of methylprednisolone on EHEB tumor cells were lower than those of different doses of dexamethasone at 24 and 48 h. The average MFI and proportion of CD19 CAR-T cells under different concentrations of glucocorticoid the proliferation inhibition of CD19 CAR-T cells by dexamethasone was higher than that of methylprednisolone. The proliferation inhibition of CD19 CAR-T cells of the two glucocorticoids in high concentration groups were more obvious than that in low concentration groups. When CD19 CAR-T cells were co-cultured with different tumor cells, the proportion and average MFI of CD19 CAR-T cells showed that the proliferation inhibition of dexamethasone was higher than that of methylprednisolone. The proliferation inhibition of CD19 CAR-T cells of the two glucocorticoids in high concentration groups was more obvious than that in low concentration groups. Conclusion: Dexamethasone inhibits the cell proliferation of CD19 CAR-T cells more than methylprednisolone during the targeting of different tumor cell lines. The inhibition effect of dexamethasone on the proliferation and amplification of CD19 CAR-T cells was greater than that of methylprednisolone during the targeting of CD19 CAR-T cells to different tumor cell lines. Moreover, the inhibition effect of the high dose group was more obvious.


Subject(s)
Glucocorticoids , Leukocytes, Mononuclear , Antigens, CD19 , B-Lymphocytes , Cell Line, Tumor , Cell Proliferation , Glucocorticoids/pharmacology , Humans , Immunotherapy, Adoptive , T-Lymphocytes
3.
Zhonghua Xue Ye Xue Za Zhi ; 42(7): 570-576, 2021 Jul 14.
Article in Chinese | MEDLINE | ID: mdl-34455744

ABSTRACT

Objective: To observe the local reactions and efficacy of CD19 CAR-T therapy in recurrence/refractory B-cell non-Hodgkin's lymphoma (R/R NHL) patients with >7.5 cm lesions. Methods: 32 R/R NHL patients with >7.5 cm lesions were enrolled and injected with CD19 CAR-T cells. Flow cytometry was used to detect and observe the amplification of CD19 CAR-T cells in vivo. Enzyme-linked immunosorbent assay (ELISA) was used to detect cytokines in peripheral blood of patients. The side effects of CD19 CAR-T cell therapy included systemic side effects and local reactions of tumor. The local side effects were observed by Ultrasound, Computed tomography and Magnetic resonance imaging. Treatment options included glucocorticoid, interleukin-6 antibody and drainage of exudate. Overall response rate (ORR) and overall survival rate (OS) were observed. Results: ①Among the 32 patients, CR (40.63%) , PR (31.25%) and ORR (71.88%) were 13, 10 and 23, respectively. ②In all 23 patients received ORR, 13 patients had grade 1-2 CRS, while 10 patients had grade 3-4 CRS. All the 9 patients in the SD+PD group had grade 1-2 CRS (P=0.030) . ③A total of 15 patients with tumor local reactions, included 9 patients with CR, 5 patients with PR and 1 patient with SD. The local reactions of the tumor included that the diameter of the superficial lesions increased with redness, swelling and heat pain. The deep lesions presented abdominal pain, abdominal distension, suffocation and local pain, and burning of the tumor. The deep lesions were enlarged or accompanied by local edema. The local exudative lesions were found in the abdominal cavity and pleural cavity. ④ Peak proportion of CD19 CAR-T cells in ORR group was higher than that of in SD+PD group[16.8% (5.3%-48.2%) vs 2.9% (1.5%-5.7%) , z=-4.297, P<0.001]. The peak proportion of CD19 CAR-T cells in ORR group with local reactions was higher than that of in patients without local reactions [22.2% (10.5%-48.2%) vs 12.6% (5.3%-21.6%) , z=-3.213, P=0.001]. The peak proportion of CD19 CAR-T cells in multiple lesion group was higher than that of in single lesion group [35.8% (1.5%-48.2%) vs 16.8% (10.5%-18.5%) , z=-2.023, P=0.040]. ⑤Occurrence of local reactions and tumor shrinkage time were both delayed compared with systemic side effects. ⑥In the ORR group, the OS of patients with tumor local reactions was longer than that of patients without tumor local reactions, but there was no difference in the two groups (75% vs 34.6%, P=0.169) . Conclusions: CD19 CAR-T cell therapy in R/R NHL patients with >7.5 cm lesions might cause tumor local reactions later than systemic side effects. Clinicaltrial:: ChiCTR1800018059.


Subject(s)
Lymphoma, B-Cell , Receptors, Chimeric Antigen , Antigens, CD19 , Humans , Lymphoma, B-Cell/therapy , Neoplasm Recurrence, Local , T-Lymphocytes
4.
Zhonghua Zhong Liu Za Zhi ; 42(12): 1007-1013, 2020 Dec 23.
Article in Chinese | MEDLINE | ID: mdl-33342156

ABSTRACT

Objective: To explore the potential mechanism of sorafenib resistance associated long non-coding RNA (lncRNA-SRLR) promoted invasion and metastasis in U2OS osteosarcoma cells. Methods: We transfected U2OS cells with negative control lentivirus (LV-NC) or lncRNA-SRLR overexpressed lentivirus (LV-over/SRLR) particles. LV-NC and LV-over/SRLR stable transfected cells (U20S/NC and U20S/SRLR) were selected by primary cell culture medium containing puromycin. The mRNA expressions of lncRNA-SRLR and procollagen-lysine, procollagen-lysine 2-oxoglutarate 5-dioxygenase 2 (PLOD2) were detected by quantitative real-time polymerase chain reaction (qRT-PCR). The effect of lncRNA-SRLR on the invasion of U2OS cells were determined by wound-healing assay and Transwell migration assay. The effect of SRLR on the interleukin-6 (IL-6) secretion of U2OS cells was evaluated by enzyme-linked immunosorbent assay (ELISA) analysis. The subcellular distribution of SRLR in U2OS cells was detected by fluorescence in situ hybridization (FISH) analysis.The expression of PLOD2 in cells was detected by immunofluorescence (IF). The expressions of PLOD2 and focal adhesion kinase (FAK)/signal transducer and activator of transcription 3 (STAT3) signal pathway related proteins in U2OS/NC and U2OS/SRLR cells were detected by western blotting. Results: qRT-PCR assay showed that mRNA expressions of lncRNA-SRLR and PLOD2 in U2OS/SRLR cells were (3 964.97±0.05) and (2.77±0.11), respectively, significantly higher than those in U2OS/NC cells (P<0.001 or P<0.01). The results of wound-healing and Transwell migration assay showed that over-expression of SRLR markedly promoted the invasion ability of U2OS cells (P<0.05). The result of ELISA analysis showed that the IL-6 secretions in U2OS/NC or U2OS/SRLR cells were (125.38±11.22) pg/ml or (119.97±13.43) pg/ml, without statistical significance (P>0.05). The subcellular distribution assay revealed that lncRNA-SRLR is predominately located in the nucleus. The result of IF showed that compared with U2OS/NC cells, the expression of PLOD2 was up-regulated in U2OS/SRLR cells. The result of western blotting showed that over-expression of SRLR significantly increased the expression levels of PLOD2, phosphorylation (p)-FAK and p-STAT3 in U2OS cells (P<0.01). Conclusion: lncRNA-SRLR promotes invasion and metastasis of osteosarcoma by activating PLOD2-FAK/STAT3 signal axis.


Subject(s)
Bone Neoplasms , Osteosarcoma , RNA, Long Noncoding , Bone Neoplasms/genetics , Bone Neoplasms/metabolism , Drug Resistance, Neoplasm/genetics , Humans , Neoplasm Invasiveness/genetics , Neoplasm Metastasis/genetics , Osteosarcoma/genetics , Osteosarcoma/metabolism , RNA, Long Noncoding/metabolism , Sorafenib/pharmacology
5.
Clin Transl Oncol ; 21(2): 197-205, 2019 Feb.
Article in English | MEDLINE | ID: mdl-29948972

ABSTRACT

PURPOSE: Detecting different molecular markers in primary tumors and metastases may provide therapeutic information. Here we investigated differences between primary tumors and four metastatic sites of lung adenocarcinoma in the biomarkers' features and discussed potential therapeutic implications. METHODS: A total of 228 patients with metastatic lung adenocarcinoma were analyzed for EGFR, KRAS, BRAF and PIK3CA mutations detected by xTAG liquidchip technology (xTAG-LCT), as well as ERCC1, TYMS, RRM1, TUBB3, STMN1, TOP2A and VEGFR1-3 mRNA expression detected by branched DNA-liquidchip technology (bDNA-LCT). RESULTS: Higher rates of low ERCC1 (35.6 vs. 20.3%, P = 0.0105), RRM1 (23.3 vs. 13.0%, P = 0.0437), STMN1 (72.2 vs. 42.8%, P = 0.0000) and high VEGFR2 (34.4 vs. 18.8%, P = 0.0078) mRNA expression were found in EGFR-mutated tumors, suggesting possible benefit from platinum, gemcitabine, taxanes or VEGFR2 inhibitors. Primary lesions showed low ERCC1 (31.6 vs. 18.5%, P = 0.0271), TYMS (17.6 vs. 7.6%, P = 0.0300), TUBB3 (16.9 vs. 7.6%, P = 0.0415), STMN1 (62.1 vs. 42.9%, P = 0.0065) and high TOP2A (48.7 vs. 33.1%, P = 0.0262) mRNA expression and higher KRAS mutations (25.7 vs. 14.1%, P = 0.0350), suggesting platinum, taxanes, pemetrexed, anti-TOP2A agents and resistant to anti-EGFR therapies. Liver metastases showed absence of low TYMS expression, indicating insensitivity to pemetrexed-based regimen. Pleura metastases harbored higher rates of high VEGFR2 expression (50.0 vs. 19.1%, P = 0.0127). Lymph node metastases presented higher rates of high VEGFR2 expression (37.5 vs. 19.1%, P = 0.0253) and EGFR mutations (59.4 vs. 34.4%, P = 0.0011), suggesting use of anti-VEGFR2 and anti-EGFR therapies. CONCLUSION: Molecular profiling of 228 lung adenocarcinomas determined a significant difference between biomarkers such as EGFR and KRAS subtypes at primary and metastatic sites. Our results serve as a reference for individual treatment based on different potential targets in metastatic lung adenocarcinoma directed by molecular profiling.


Subject(s)
Adenocarcinoma of Lung/secondary , Biomarkers, Tumor/analysis , Lung Neoplasms/pathology , Neoplasm Metastasis/pathology , Adenocarcinoma of Lung/genetics , Adult , Aged , Female , Humans , Lung Neoplasms/genetics , Male , Middle Aged , Molecular Targeted Therapy , Neoplasm Metastasis/genetics
6.
Carbohydr Polym ; 174: 464-473, 2017 Oct 15.
Article in English | MEDLINE | ID: mdl-28821093

ABSTRACT

In order to understand the chemical structure of chitin-based acrylate superabsorbent polymers (SAP), chitin was dissolved in NaOH aqueous solution via freezing-thawing cyclic treatment without urea, subsequently, a transparent hydrogel was prepared by copolymerizing the alkali-chitin solution and acrylic acid directly. The effects of the degree of deacetylation (DDA) and the molecular weight (Mw) of chitin on the properties of SAP were investigated in detail. With increasing the DDA and Mw, the yield improved while the water absorbency decreased, yet the effect of DDA is insignificant if the Mw is smaller enough. The structures were characterized by FT-IR, XRD, TG, DSC, XPS, solid-state 13C NMR and elemental analyses. The results indicated that the poly(acrylic acid) chains were successfully grafted onto the chitin backbones, and the reaction sites were the NH2 on the chitosan units. The possible mechanism was further discussed, which was similar to that suggested for chitosan-g-poly(acrylic acid) SAP.

7.
Neoplasma ; 64(2): 182-191, 2017.
Article in English | MEDLINE | ID: mdl-28043144

ABSTRACT

The activation of AKT is one of the causes of resistance to epidermal growth factor receptor (EGFR)- tyrosine kinase inhibitors (TKIs). Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) combines with related receptors to trigger apoptosis or protect the cells against TRAIL apoptosis. This research focused on the association of EGFR and KRAS mutations with expression of AKT, p-AKT, DR5 and DcR1 in non-small cell lung cancer. 82 NSCLC patients were included in the study. xTAG liquichip techonolgy (xTAG-LCT) was applied to investigate the genetic mutation of EGFR and KRAS, Quantitative Real-time PCR was used to test the mRNA expression of AKT, DR5 and DcR1 and Western Blot was applied to test the protein expression of AKT, p-AKT, DR5, and DcR1. We found that of 82 patients, 31 cases had EGFR-activating mutations, more common in female, adenocarcinoma, and non-smoker patients; 9 cases had KRAS mutations, frequently found in patients with smoking history. The expression of AKT and p-AKT correlated with staging, tumor differentiation, and lymph node metastasis. The expression of DR5 in phase III and low differentiation tumor was significantly higher than that in phase I+II and high and median differentiation tumor; the expression of DcR1 in phase III and low differentiation tumor was significantly lower than that in phase I+II and high and median differentiation tumor. Compared with EGFR and KRAS wild type, in NSCLC tissue with EGFR and KRAS mutations, the expression of AKT and p-AKT was significantly higher. These results suggest that EGFR and KRAS mutation status was associated with the expression of AKT and p-AKT. AKT, p-AKT, DR5, and DcR1 all took part in the occurrence and development of NSCLC, and may become a reference index to evaluate the prognosis of NSCLC.


Subject(s)
Carcinoma, Non-Small-Cell Lung/genetics , Lung Neoplasms/genetics , Proto-Oncogene Proteins p21(ras)/genetics , ErbB Receptors/genetics , Female , GPI-Linked Proteins/genetics , GPI-Linked Proteins/metabolism , Humans , Male , Mutation , Proto-Oncogene Proteins c-akt/genetics , Proto-Oncogene Proteins c-akt/metabolism , Receptors, TNF-Related Apoptosis-Inducing Ligand/genetics , Receptors, TNF-Related Apoptosis-Inducing Ligand/metabolism , Receptors, Tumor Necrosis Factor, Member 10c/genetics , Receptors, Tumor Necrosis Factor, Member 10c/metabolism
8.
Expert Rev Cardiovasc Ther ; 12(6): 659-66, 2014 Jun.
Article in English | MEDLINE | ID: mdl-24697521

ABSTRACT

Fibroblast growth factor 21 (FGF21) is a peptide hormone secreted by the liver, adipocytes, pancreas and skeletal muscle. It acts locally but is also a circulating hormone. Administration of FGF21 in animals and humans results in a decrease in body weight, blood triglycerides and LDL-cholesterol, with improvement in insulin sensitivity. FGF21 is known to play an important role during fasting and starvation by stimulating gluconeogenesis in the liver and inducing lipolysis in white adipose tissues. FGF21 expression is mediated by the peroxisome proliferator-activated receptor-α, while its biological actions are mediated through binding to a complex formed by its receptors and an essential coreceptor, ß-Klotho. Serum FGF21 levels are paradoxically elevated in obesity, suggesting a decreased responsiveness. Recent data showed that serum FGF21 level is elevated in hypertension, atherosclerosis and coronary artery disease, raising the possibility that FGF21 plays a role in the pathophysiology of these diseases.


Subject(s)
Fibroblast Growth Factors/metabolism , Obesity/physiopathology , Animals , Atherosclerosis/physiopathology , Body Weight/physiology , Coronary Artery Disease/physiopathology , Fibroblast Growth Factors/blood , Humans , Hypertension/physiopathology , Klotho Proteins , Membrane Proteins/metabolism , Obesity/complications , PPAR alpha/metabolism
9.
Neoplasma ; 59(1): 18-29, 2012.
Article in English | MEDLINE | ID: mdl-22017589

ABSTRACT

The death ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can selectively induce apoptosis in tumor cells. But studies have demonstrated that many tumor cells were resistant to TRAIL-induced apoptosis. CYLD is recognized as a negative regulator of nuclear factor-kappa B(NF-κB) activity. To explore a correlation between CYLD expression and responsiveness to TRAIL in lung cancer cell lines, we established lung cancer cell lines that stably express CYLD. Our data provided the first evidence that increased expression of CYLD directly blocks TRAIL-induced NF-κB activation, and consequently increases TRAIL-induced apoptosis in lung cancer cells. CYLD may act as a therapeutic target of lung cancer. Targeting CYLD, in combination with TRAIL, may be a new strategy to treat lung cancer with high NF-κB activity.


Subject(s)
Adenocarcinoma/pathology , Lung Neoplasms/pathology , NF-kappa B/metabolism , Neoplasm Proteins/physiology , TNF-Related Apoptosis-Inducing Ligand/pharmacology , Tumor Suppressor Proteins/physiology , Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Cell Line, Tumor/drug effects , Cell Line, Tumor/metabolism , Clinical Trials as Topic , Deubiquitinating Enzyme CYLD , Down-Regulation , Drug Resistance, Neoplasm , Gene Expression Regulation, Neoplastic , Genetic Vectors , Humans , Inhibitor of Apoptosis Proteins/biosynthesis , Inhibitor of Apoptosis Proteins/genetics , Lentivirus , Molecular Targeted Therapy , Real-Time Polymerase Chain Reaction , Recombinant Fusion Proteins/pharmacology , Recombinant Fusion Proteins/physiology , Signal Transduction/drug effects
10.
Brain Res ; 898(2): 204-14, 2001 Apr 20.
Article in English | MEDLINE | ID: mdl-11306006

ABSTRACT

By metabolically labeling tissue slices from striatum and thalamus with [32P]orthophosphoric acid and immunoprecipitating the receptor with mu receptor-specific antiserum, we found that the endogenous mu receptor in the brain tissue did undergo phosphorylation. The phosphorylation occurred at basal level (no drug treatment) and was enhanced with DAMGO-treatment. The enhancement of the phosphorylation was blocked by naloxone. Morphine stimulation also increased the phosphorylation, but the amount of enhancement was less than that caused by DAMGO-treatment. Mu receptor phosphorylation in the thalamus was much greater than the striatum, while no phosphorylation of the mu receptor in the cerebellum was detected, even with DAMGO treatment. The extent of mu receptor phosphorylation identified in the thalamus, striatum and cerebellum is consistent with the previous studies of mu receptor distribution. The time course and dose-response studies demonstrated that mu receptor phosphorylation was a rapid event, exhibited a positive dose-dependent response, and was similar to that observed in the cloned mu receptor in CHO cells. Furthermore, we correlated the change of mu receptor phosphorylation with the desensitization of the mu receptor function, specifically, inhibition of adenylyl cyclase activity in the thalamus of morphine-tolerant rats. We found that in the thalamus of rats chronically treated with morphine, the enhancement of mu receptor phosphorylation in basal and DAMGO-treated samples paralleled the desensitization of DAMGO-mediated inhibition of adenylyl cyclase. Our results suggest that mu receptor phosphorylation in vivo may play an important role in the modulation of mu receptor function following both acute exposure to morphine and during the development of morphine tolerance.


Subject(s)
Narcotics/pharmacology , Receptors, Opioid, mu/agonists , Thalamus/drug effects , Adenylyl Cyclases/drug effects , Adenylyl Cyclases/metabolism , Analgesics, Opioid/pharmacology , Animals , Cerebellum/drug effects , Cerebellum/metabolism , Dose-Response Relationship, Drug , Drug Administration Schedule , Drug Tolerance/physiology , Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology , Immunohistochemistry , Male , Morphine/pharmacology , Naloxone/pharmacology , Narcotic Antagonists/pharmacology , Neostriatum/drug effects , Neostriatum/metabolism , Organ Culture Techniques , Phosphorylation/drug effects , Rats , Rats, Sprague-Dawley , Receptors, Opioid, mu/metabolism , Thalamus/metabolism , Time Factors
11.
Biochemistry ; 39(18): 5492-9, 2000 May 09.
Article in English | MEDLINE | ID: mdl-10820022

ABSTRACT

Determining which domains and amino acid residues of the mu opioid receptor are phosphorylated is critical for understanding the mechanism of mu opioid receptor phosphorylation. The role of the C-terminus of the receptor was investigated by examining the C-terminally truncated or point-mutated mu opioid receptors in receptor phosphorylation and desensitization. Both wild-type and mutated receptors were stably expressed in Chinese hamster ovary (CHO) cells. The receptor expression was confirmed by receptor radioligand binding and immunoblottting. After exposure to 5 microM of DAMGO, phosphorylation of the C-terminally truncated receptor and the mutant receptor T394A was reduced to 40 and 10% of that of the wild-type receptor, respectively. Mutation effects on agonist-induced desensitization were studied using adenylyl cyclase inhibition assays. The C-terminally truncated receptor and mutant receptor T394A both showed complete loss of DAMGO-induced desensitization, while the mutant T/S-7A receptor only lost part of its ability to desensitize. Taken together, these results suggest that the C-terminus of the mu opioid receptor participates in receptor phosphorylation and desensitization with threonine 394, a crucial residue for both features. DAMGO-induced mu opioid receptor phosphorylation and desensitization are associated and appear to involve both the mu opioid receptor C-terminus and other domains of the receptor.


Subject(s)
Receptors, Opioid, mu/genetics , Adenylyl Cyclases/metabolism , Amino Acid Sequence , Animals , CHO Cells , Colforsin/pharmacology , Cricetinae , Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/metabolism , Humans , Molecular Sequence Data , Mutation , Phosphorylation , Protein Binding/genetics , Receptors, Opioid, mu/chemistry , Transfection
12.
J Pharmacol Exp Ther ; 293(1): 113-20, 2000 Apr.
Article in English | MEDLINE | ID: mdl-10734160

ABSTRACT

The effects of sulfhydryl-specific methanethiosulfonate (MTS) derivatives on mu-opioid receptor binding were examined in Chinese hamster ovary (CHO) cells that stably express mu-opioid receptors (HmuCHO). Three charged MTS derivatives inhibited the binding of [(3)H][D-Ala(2),N-MePhe(4),Gly-ol(5)]-enkephalin to mu-opioid receptors with IC(50) values ranging from 0.12 to 13 mM. Further characterization of the mu-opioid receptor interactions with ethylammonium MTS (the most potent among tested MTS reagents) revealed that ethylammonium MTS inhibition of ligand binding to the receptor was irreversible, with both the maximal receptor binding (B(max)) and the binding affinity (K(d)) being changed. Preincubation of HmuCHO cells with [D-Ala(2),N-MePhe(4), Gly-ol(5)]-enkephalin or naloxone prevented the receptor inactivation normally caused by MTS derivatives, indicating that the reactions may occur within or near the ligand-binding pocket on the receptor. To identify the susceptible sulfhydryl groups, each of the cysteine residues in the mu-receptor transmembrane domains were substituted with serine by site-directed mutagenesis. All of the mutant receptors transiently expressed in COS cells had receptor binding properties similar to the wild-type receptors. However, four mutant receptors with a serine substitution in transmembrane domain III (C161S), IV (C192S), V (C237S), or VII (C332S) displayed significant resistance against MTS inhibition compared with the wild-type receptor. We conclude that these four cysteine residues react with MTS reagents and are responsible for the effect of the MTS reagents on mu-opioid receptor binding.


Subject(s)
Cysteine/chemistry , Receptors, Opioid, mu/drug effects , Sulfhydryl Reagents/pharmacology , Alanine/chemistry , Amino Acid Sequence , Amino Acid Substitution , Animals , CHO Cells , COS Cells/drug effects , Cricetinae , Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/metabolism , Ethyl Methanesulfonate/analogs & derivatives , Ethyl Methanesulfonate/chemistry , Ethyl Methanesulfonate/pharmacology , Humans , Ligands , Membranes/chemistry , Membranes/drug effects , Membranes/metabolism , Mesylates/chemistry , Mesylates/pharmacology , Molecular Sequence Data , Mutagenesis, Site-Directed , Naloxone/metabolism , Narcotic Antagonists/metabolism , Radioligand Assay , Receptors, Opioid, mu/chemistry , Receptors, Opioid, mu/genetics , Sulfhydryl Reagents/chemistry
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