shengwen lei | Wuhan University (original) (raw)
Papers by shengwen lei
Febs Letters, 1998
Endomorphins were recently identified as endogenous ligands with high selectivity for mu opioid r... more Endomorphins were recently identified as endogenous ligands with high selectivity for mu opioid receptors. We have characterized the ability of endomorphins to bind to and functionally activate the cloned human mu opioid receptor. Both endomorphin-1 and endomorphin-2 exhibited binding selectivity for the mu opioid receptor over the delta and kappa opioid receptors. Both agonists inhibited forskolin-stimulated increase of cAMP in a dose-dependent fashion. When the mu opioid receptor was coexpressed in Xenopus oocytes with G proteinactivated K + channels, application of either endomorphin activated an inward K + current. This activation was dosedependent and blocked by naloxone. Both endomorphins acted as full agonists with efficacy similar to that of [D-Ala P ,N-Me-Phe R ,Gly-ol S ]enkephalin (DAMGO). These data indicate that endomorphins act as full agonists at the human mu opioid receptor, capable of stimulating the receptor to inhibit the cAMP/adenylyl cyclase pathway and activate G-protein-activated inwardly rectifying potassium (GIRK) channels.
Food Chemistry, 2011
The effect of sonication on proteolytic hydrolysis of ovotransferrin and bioactivities of the hyd... more The effect of sonication on proteolytic hydrolysis of ovotransferrin and bioactivities of the hydrolysates were investigated, and the large peptide fragments left in the hydrolysate were characterised. The results showed that sonication could increase the reactive sulphydryl groups in 5% ovotransferrin solution by 50%, although there were no improvements in the overall degree of hydrolysis. Furthermore, SDS–PAGE and reverse-phase HPLC profiles did not show difference of the treated samples. Angiotensin-converting enzyme (ACE) inhibitory activity, but not antioxidant activity, of the thermolysin hydrolysate was improved in a dose dependent manner at prolonged sonication time. Matrix assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF/MS) analysis revealed that thermolysin hydrolysate was composed of 926 peptides, of 99% having masses lower than 10kDa and of 1% larger than 10kDa derived from both N- and C-lobes of ovotransferrin.
Febs Letters, 1996
The weaver mutation in mice has recently been identified as a single base-pair mutation in the Gi... more The weaver mutation in mice has recently been identified as a single base-pair mutation in the Girk2 gene, which encodes a G-protein-activated inwardly rectifying potassium channel, GIRK2. The mutation results in a Gly to Ser substitution at residue 156, in the putative pore-forming region of the potassium channel. In the present study, we used Xenopus oocytes to express mutant GIRK2, and to characterize the effects of the mutation on the channel. The mutation results in a loss of the normal high selectivity for K ÷ over Na ÷, with little effect on other channel properties such as activation by the mu opioid receptor. The resulting increase in basal Na ÷ permeability causes a marked depolarization of oocytes expressing the mutant GIRK2 protein. This result was observed even when the mutant GIRK2 was coexpressed with GIRK1, a situation more analogous to that seen in vivo. Thus, the increased Na ÷ permeability and resulting depolarization may contribute to the pathology of cerebellar granule cells and substantia nigra dopaminergic neurons observed in the weaver mice.
Proceedings of The National Academy of Sciences, 1998
Opioid drugs play important roles in the clinical management of pain, as well as in the developme... more Opioid drugs play important roles in the clinical management of pain, as well as in the development and treatment of drug abuse. The mu opioid receptor is the primary site of action for the most commonly used opioids, including morphine, heroin, fentanyl, and methadone. By sequencing DNA from 113 former heroin addicts in methadone maintenance and 39 individuals with no history of drug or alcohol abuse or dependence, we have identified five different single-nucleotide polymorphisms (SNPs) in the coding region of the mu opioid receptor gene. The most prevalent SNP is a nucleotide substitution at position 118 (A118G), predicting an amino acid change at a putative N-glycosylation site. This SNP displays an allelic frequency of approximately 10% in our study population. Significant differences in allele distribution were observed among ethnic groups studied. The variant receptor resulting from the A118G SNP did not show altered binding affinities for most opioid peptides and alkaloids tested. However, the A118G variant receptor binds -endorphin, an endogenous opioid that activates the mu opioid receptor, approximately three times more tightly than the most common allelic form of the receptor. Furthermore, -endorphin is approximately three times more potent at the A118G variant receptor than at the most common allelic form in agonist-induced activation of G protein-coupled potassium channels. These results show that SNPs in the mu opioid receptor gene can alter binding and signal transduction in the resulting receptor and may have implications for normal physiology, therapeutics, and vulnerability to develop or protection from diverse diseases including the addictive diseases.
BMC Neuroscience, 2003
Background: G protein-coupled receptors (GPCRs) interact with heterotrimeric GTP-binding proteins... more Background: G protein-coupled receptors (GPCRs) interact with heterotrimeric GTP-binding proteins (G proteins) to modulate acute changes in intracellular messenger levels and ion channel activity. In contrast, long-term changes in cellular growth, proliferation and differentiation are often mediated by tyrosine kinase receptors and certain GPCRs by activation of mitogen-activated protein (MAP) kinases. Complex interactions occur between these signaling pathways, but the specific mechanisms of such regulatory events are not well-understood. In particular it is not clear whether GPCRs are modulated by tyrosine kinase receptor-MAP kinase pathways.
The opioid receptor is thought to be the cellular target of opioid narcotics such as morphine and... more The opioid receptor is thought to be the cellular target of opioid narcotics such as morphine and heroin, mediating their effects in both pain relief and euphoria. Its involvement is also implicated in a range of diverse biological processes. Using a mouse model in which the receptor gene was disrupted by targeted homologous recombination, we explored the involvement of this receptor in a number of physiological functions. Mice homozygous for the disrupted gene developed normally, but their motor function was altered. Drug-naive homozygotes displayed reduced locomotor activity, and morphine did not induce changes in locomotor activity observed in wild-type mice. Unexpectedly, lack of a functional receptor resulted in changes in both the host defense system and the reproductive system. We observed increased proliferation of granulocyte-macrophage, erythroid, and multipotential progenitor cells in both bone marrow and spleen, indicating a link between hematopoiesis and the opioid system, both of which are stress-responsive systems. Unexpected changes in sexual function in male homozygotes were also observed, as shown by reduced mating activity, a decrease in sperm count and motility, and smaller litter size. Taken together, these results suggest a novel role of the opioid receptor in hematopoiesis and reproductive physiology, in addition to its known involvement in pain relief.
Based on simplified Extended Kalman Filter (EKF), a novel signal extraction method based on FPGA ... more Based on simplified Extended Kalman Filter (EKF), a novel signal extraction method based on FPGA was presented, which can not only extract rotor position information but also filter fundamental frequency control current. Compared with traditional IIR and FIR filter, the novel EKF, adopting iterative algorithm, has faster filter speed and better filter performance. It can eliminate low-pass filter in control feedback loop. So the dynamic performance and stability of the system is enhanced and the design of system controller is simplified. At the same time, since there is no high frequency signal component in control circuit, the controller affection to high frequency position estimation is decreased. The design of position estimator is unaffected by control regulator and simplified. Finally, Simulation and experiment test was adopted to verify this method.
Ultramicroscopy, 2000
Recent development of atomic force microscopy (AFM) applications in imaging living cells is revie... more Recent development of atomic force microscopy (AFM) applications in imaging living cells is reviewed, focusing on technical progress and application advancements made in the following major areas: (i) high-resolution imaging of cellular structures, (ii) real-time monitoring of cellular dynamic processes, and (iii) detecting micromechanical properties of the cell. Technical and Abbreviations: AFM = atomic force microscopy; PCT = patch clamp technique; NPC = nuclear pore complex; F-S = force versus distance; TMAFM = tapping mode atomic force microscopy; SICM = scanning ionconductance microscope; FIEL = force integration to equal limits; SNOM = scanning near-field optical microscopy experimental difficulties frequently encountered in AFM applications in above areas are presented and possible strategies for overcoming these obstacles are discussed. Significant advances in the AFM study of living cells can be achieved from further development of AFM technology, sample preparation, and innovative applications.
Febs Letters, 1998
Endomorphins were recently identified as endogenous ligands with high selectivity for mu opioid r... more Endomorphins were recently identified as endogenous ligands with high selectivity for mu opioid receptors. We have characterized the ability of endomorphins to bind to and functionally activate the cloned human mu opioid receptor. Both endomorphin-1 and endomorphin-2 exhibited binding selectivity for the mu opioid receptor over the delta and kappa opioid receptors. Both agonists inhibited forskolin-stimulated increase of cAMP in a dose-dependent fashion. When the mu opioid receptor was coexpressed in Xenopus oocytes with G proteinactivated K + channels, application of either endomorphin activated an inward K + current. This activation was dosedependent and blocked by naloxone. Both endomorphins acted as full agonists with efficacy similar to that of [D-Ala P ,N-Me-Phe R ,Gly-ol S ]enkephalin (DAMGO). These data indicate that endomorphins act as full agonists at the human mu opioid receptor, capable of stimulating the receptor to inhibit the cAMP/adenylyl cyclase pathway and activate G-protein-activated inwardly rectifying potassium (GIRK) channels.
Food Chemistry, 2011
The effect of sonication on proteolytic hydrolysis of ovotransferrin and bioactivities of the hyd... more The effect of sonication on proteolytic hydrolysis of ovotransferrin and bioactivities of the hydrolysates were investigated, and the large peptide fragments left in the hydrolysate were characterised. The results showed that sonication could increase the reactive sulphydryl groups in 5% ovotransferrin solution by 50%, although there were no improvements in the overall degree of hydrolysis. Furthermore, SDS–PAGE and reverse-phase HPLC profiles did not show difference of the treated samples. Angiotensin-converting enzyme (ACE) inhibitory activity, but not antioxidant activity, of the thermolysin hydrolysate was improved in a dose dependent manner at prolonged sonication time. Matrix assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF/MS) analysis revealed that thermolysin hydrolysate was composed of 926 peptides, of 99% having masses lower than 10kDa and of 1% larger than 10kDa derived from both N- and C-lobes of ovotransferrin.
Febs Letters, 1996
The weaver mutation in mice has recently been identified as a single base-pair mutation in the Gi... more The weaver mutation in mice has recently been identified as a single base-pair mutation in the Girk2 gene, which encodes a G-protein-activated inwardly rectifying potassium channel, GIRK2. The mutation results in a Gly to Ser substitution at residue 156, in the putative pore-forming region of the potassium channel. In the present study, we used Xenopus oocytes to express mutant GIRK2, and to characterize the effects of the mutation on the channel. The mutation results in a loss of the normal high selectivity for K ÷ over Na ÷, with little effect on other channel properties such as activation by the mu opioid receptor. The resulting increase in basal Na ÷ permeability causes a marked depolarization of oocytes expressing the mutant GIRK2 protein. This result was observed even when the mutant GIRK2 was coexpressed with GIRK1, a situation more analogous to that seen in vivo. Thus, the increased Na ÷ permeability and resulting depolarization may contribute to the pathology of cerebellar granule cells and substantia nigra dopaminergic neurons observed in the weaver mice.
Proceedings of The National Academy of Sciences, 1998
Opioid drugs play important roles in the clinical management of pain, as well as in the developme... more Opioid drugs play important roles in the clinical management of pain, as well as in the development and treatment of drug abuse. The mu opioid receptor is the primary site of action for the most commonly used opioids, including morphine, heroin, fentanyl, and methadone. By sequencing DNA from 113 former heroin addicts in methadone maintenance and 39 individuals with no history of drug or alcohol abuse or dependence, we have identified five different single-nucleotide polymorphisms (SNPs) in the coding region of the mu opioid receptor gene. The most prevalent SNP is a nucleotide substitution at position 118 (A118G), predicting an amino acid change at a putative N-glycosylation site. This SNP displays an allelic frequency of approximately 10% in our study population. Significant differences in allele distribution were observed among ethnic groups studied. The variant receptor resulting from the A118G SNP did not show altered binding affinities for most opioid peptides and alkaloids tested. However, the A118G variant receptor binds -endorphin, an endogenous opioid that activates the mu opioid receptor, approximately three times more tightly than the most common allelic form of the receptor. Furthermore, -endorphin is approximately three times more potent at the A118G variant receptor than at the most common allelic form in agonist-induced activation of G protein-coupled potassium channels. These results show that SNPs in the mu opioid receptor gene can alter binding and signal transduction in the resulting receptor and may have implications for normal physiology, therapeutics, and vulnerability to develop or protection from diverse diseases including the addictive diseases.
BMC Neuroscience, 2003
Background: G protein-coupled receptors (GPCRs) interact with heterotrimeric GTP-binding proteins... more Background: G protein-coupled receptors (GPCRs) interact with heterotrimeric GTP-binding proteins (G proteins) to modulate acute changes in intracellular messenger levels and ion channel activity. In contrast, long-term changes in cellular growth, proliferation and differentiation are often mediated by tyrosine kinase receptors and certain GPCRs by activation of mitogen-activated protein (MAP) kinases. Complex interactions occur between these signaling pathways, but the specific mechanisms of such regulatory events are not well-understood. In particular it is not clear whether GPCRs are modulated by tyrosine kinase receptor-MAP kinase pathways.
The opioid receptor is thought to be the cellular target of opioid narcotics such as morphine and... more The opioid receptor is thought to be the cellular target of opioid narcotics such as morphine and heroin, mediating their effects in both pain relief and euphoria. Its involvement is also implicated in a range of diverse biological processes. Using a mouse model in which the receptor gene was disrupted by targeted homologous recombination, we explored the involvement of this receptor in a number of physiological functions. Mice homozygous for the disrupted gene developed normally, but their motor function was altered. Drug-naive homozygotes displayed reduced locomotor activity, and morphine did not induce changes in locomotor activity observed in wild-type mice. Unexpectedly, lack of a functional receptor resulted in changes in both the host defense system and the reproductive system. We observed increased proliferation of granulocyte-macrophage, erythroid, and multipotential progenitor cells in both bone marrow and spleen, indicating a link between hematopoiesis and the opioid system, both of which are stress-responsive systems. Unexpected changes in sexual function in male homozygotes were also observed, as shown by reduced mating activity, a decrease in sperm count and motility, and smaller litter size. Taken together, these results suggest a novel role of the opioid receptor in hematopoiesis and reproductive physiology, in addition to its known involvement in pain relief.
Based on simplified Extended Kalman Filter (EKF), a novel signal extraction method based on FPGA ... more Based on simplified Extended Kalman Filter (EKF), a novel signal extraction method based on FPGA was presented, which can not only extract rotor position information but also filter fundamental frequency control current. Compared with traditional IIR and FIR filter, the novel EKF, adopting iterative algorithm, has faster filter speed and better filter performance. It can eliminate low-pass filter in control feedback loop. So the dynamic performance and stability of the system is enhanced and the design of system controller is simplified. At the same time, since there is no high frequency signal component in control circuit, the controller affection to high frequency position estimation is decreased. The design of position estimator is unaffected by control regulator and simplified. Finally, Simulation and experiment test was adopted to verify this method.
Ultramicroscopy, 2000
Recent development of atomic force microscopy (AFM) applications in imaging living cells is revie... more Recent development of atomic force microscopy (AFM) applications in imaging living cells is reviewed, focusing on technical progress and application advancements made in the following major areas: (i) high-resolution imaging of cellular structures, (ii) real-time monitoring of cellular dynamic processes, and (iii) detecting micromechanical properties of the cell. Technical and Abbreviations: AFM = atomic force microscopy; PCT = patch clamp technique; NPC = nuclear pore complex; F-S = force versus distance; TMAFM = tapping mode atomic force microscopy; SICM = scanning ionconductance microscope; FIEL = force integration to equal limits; SNOM = scanning near-field optical microscopy experimental difficulties frequently encountered in AFM applications in above areas are presented and possible strategies for overcoming these obstacles are discussed. Significant advances in the AFM study of living cells can be achieved from further development of AFM technology, sample preparation, and innovative applications.