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Biomedical subjects

Jin Ye

Publications and source records attributed to Jin Ye.

At least 19 recordsLinked to original sources
PubMed2006

Sterol-regulated degradation of Insig-1 mediated by the membrane-bound ubiquitin ligase gp78.

Insig-1 and Insig-2, closely related endoplasmic reticulum membrane proteins, mediate transcriptional and post-transcriptional mechanisms that assure cholesterol homeostasis through their sterol-induced binding to Scap (SREBP cleavage-activating protein) and 3-hydroxy-3-methylglutaryl coenzyme A reductase. Recent studies show that Insig-1 (but not Insig-2) is ubiquitinated and rapidly degraded when cells are depleted of sterols. Conversely, ubiquitination of Insig-1 is blocked, and the protein is stabilized when intracellular sterols accumulate. Here, we report that the ubiquitin ligase gp78, which binds with much higher affinity to Insig-1 than Insig-2, is required for ubiquitination and degradation of Insig-1 in sterol-depleted cells. Sterols prevent Insig-1 ubiquitination and degradation by displacing gp78 from Insig-1, an event that results from sterol-induced binding of Scap to Insig-1. In addition to providing a mechanism for sterol-regulated degradation of Insig-1, these results help to explain why Scap is subject to endoplasmic reticulum retention upon Insig-1 binding, whereas 3-hydroxy-3-methylglutaryl coenzyme A reductase is ubiquitinated and degraded.

Cell Line↗
PubMed2006

Juxtamembranous aspartic acid in Insig-1 and Insig-2 is required for cholesterol homeostasis.

Insig-1 and Insig-2 are closely related proteins of the endoplasmic reticulum (ER) that mediate feedback control of cholesterol synthesis by sterol-dependent binding to the following two membrane proteins: the escort protein Scap, thus preventing proteolytic processing of sterol regulatory element-binding proteins; and the cholesterol biosynthetic enzyme 3-hydroxy-3-methylglutaryl CoA reductase, thus inducing the ubiquitination and ER-associated degradation of the enzyme. Here, we report that the conserved Asp-205 in Insig-1, which abuts the fourth transmembrane helix at the cytosolic side of the ER membrane, is essential for its dual function. When Asp-205 was mutated to alanine, the mutant Insig-1 lost the ability to bind to Scap and, thus, was unable to suppress the cleavage of sterol regulatory element-binding proteins. The mutant Insig-1 was ineffective also in accelerating sterol-stimulated degradation of 3-hydroxy-3-methylglutaryl CoA reductase. Alanine substitution of the corresponding aspartic acid in Insig-2 produced the same dual defects. These studies identify a single amino acid residue that is crucial for the function of Insig proteins in regulating cholesterol homeostasis in mammalian cells.

Amino Acid Sequence↗
PubMed2006

Proteasomal degradation of ubiquitinated Insig proteins is determined by serine residues flanking ubiquitinated lysines.

Insig-1 and Insig-2 are closely related proteins of the endoplasmic reticulum that play crucial roles in cholesterol homeostasis by inhibiting excessive cholesterol synthesis and uptake. In sterol-depleted cells Insig-1 is degraded at least 15 times more rapidly than Insig-2, owing to ubiquitination of Lys-156 and Lys-158 in Insig-1. In this study, we use domain-swapping methods to localize amino acid residues responsible for this differential degradation. In the case of Insig-2, Glu-214 stabilizes the protein by preventing ubiquitination. When Glu-214 is changed to alanine, Insig-2 becomes ubiquitinated, but it is still not degraded as rapidly as ubiquitinated Insig-1. The difference in the degradation rates is traced to two amino acids: Ser-149 in Insig-1 and Ser-106 in Insig-2. Ser-149, which lies NH(2)-terminal to the ubiquitination sites, accelerates the degradation of ubiquitinated Insig-1. Ser-106, which is COOH-terminal to the ubiquitination sites, retards the degradation of ubiquitinated Insig-2. The current studies indicate that the degradation of ubiquitinated Insigs is controlled by serine residues flanking the sites of ubiquitination.

Amino Acid Sequence↗
PubMed2006

Sterol-regulated ubiquitination and degradation of Insig-1 creates a convergent mechanism for feedback control of cholesterol synthesis and uptake.

This paper describes a convergent mechanism for the feedback control of cholesterol synthesis and uptake mediated by SREBPs, membrane bound transcription factors. Endoplasmic reticulum (ER) bound SREBPs form complexes with Scap, a polytopic ER protein. In sterol-overloaded cells, Scap/SREBP binds to Insig-1, which retains the complex in the ER. Upon sterol deprivation, the Scap/SREBP complex dissociates from Insig-1, which is then ubiquitinated on lysines 156 and 158 and degraded in proteasomes. Scap/SREBP moves to the Golgi, where SREBP is processed to liberate a nuclear fragment that activates genes for cholesterol synthesis and uptake and the gene for Insig-1. Ubiquitination is not necessary for release of Scap/SREBP from Insig-1, but it establishes a requirement for synthesis of new Insig-1 for feedback inhibition. When the new Insig-1 and cholesterol converge on Scap, Scap/SREBP binds to Insig-1, preventing ubiquitination. The Insig-1/Scap/SREBP complex accumulates in the ER, ready for liberation when the cell is again sterol deprived.

Animals↗
PubMed2006

[Investigation of GR mRNA quantu expression in chronic sinusitis and nasal polyps].

OBJECTIVE: To detect the expression of the glucocorticoid receptor-alpha/beta (GR-alpha/beta) mRNA in nasal polyp and normal nasal mucosa and investigate the significance of receptor-alpha/beta in GC-insensitive and GC-sensitive patients. METHODS: The expression of GR-alpha/beta mRNA in 40 samples of nasal polyp and 30 normal nasal mucosa was examined by using Fluorescent quantitative PCR. RESULTS: Forty cases were screened from the 80 cases after follow-up, including 26 cases of GC-sensitive and 14 cases of GC-insensitive. the levels of GR-beta mRNA in group of GC-insensitive [(5.72 +/- 0.58) x 10(2) copy/microg] were significantly higher than that of GC-sensitive [(4.82 +/- 0.28) x 10(2) copy/microg, t = -6.65, P < 0.01] and normal nasal mucosa [(4.44 +/- 0.35) x 10(2) copy/microg, t = -9.19, P < 0.01]. There was difference between group of GC-insensitive and other two groups of GC-sensitive and normal nasal mucosa (P < 0.01). The ratio of GR-alpha/GR-beta showed significant difference between the group of GC-sensitive (829.42 +/- 67.36) and that of GC-insensitive (535.70 +/- 89. 00, t = 11.74, P < 0.01). CONCLUSIONS: The high expression of GR-beta mRNA and low expression of GR-alpha mRNA in nasal polyp show the status of "insensitive" in chronic sinusitis and nasal polyp. The GR-beta may play an important role in evaluating the effect of glucocorticoid in chronic sinusitis and nasal polyps.

Adult↗
PubMed2005

Activation of membrane cholesterol by displacement from phospholipids.

We tested the hypothesis that certain membrane-intercalating agents increase the chemical activity of cholesterol by displacing it from its low activity association with phospholipids. Octanol, 1,2-dioctanoyl-sn-glycerol (a diglyceride), and N-hexanoyl-D-erythrosphingosine (a ceramide) were shown to increase both the rate of transfer and the extent of equilibrium partition of human red blood cell cholesterol to methyl-beta-cyclodextrin. These agents also promoted the interaction of the sterol with two cholesterol-specific probes, cholesterol oxidase and saponin. Expanding the pool of bilayer phospholipids with lysophosphatides countered these effects. The three intercalators also protected the red cells against lysis by cholesterol depletion as if substituting for the extracted sterol. As is the case for excess plasma membrane cholesterol, treating human fibroblasts with octanol, diglyceride, or ceramide stimulated the rapid inactivation of their hydroxymethylglutaryl-CoA reductase, presumably through an increase in the pool of endoplasmic reticulum cholesterol. These data supported the stated hypothesis and point to competition between cholesterol and endogenous and exogenous intercalators for association with membrane phospholipids. We also describe simple screens using red cells in a microtiter well format to identify intercalating agents that increase or decrease the activity of membrane cholesterol.

Binding, Competitive↗
PubMed2005

Identification of FBL2 as a geranylgeranylated cellular protein required for hepatitis C virus RNA replication.

We recently reported that Hepatitis C virus (HCV) RNA replication requires one or more geranylgeranylated host proteins. Using a combination of [(3)H]mevalonate labeling, coimmunoprecipitation, and bioinformatic search, we identified a geranylgeranylated host protein required for HCV RNA replication. This protein, FBL2, contains an F box domain and a CAAX motif (CVIL). It forms a stable immunoprecipitable complex with the HCV nonstructural protein 5A (NS5A). The association of FBL2 with NS5A requires the CAAX motif of FBL2, but not the F box. Deletion of the F box created a dominant-negative protein that inhibited replication of HCV RNA when overexpressed in Huh7-K2040 cells; this inhibition was overcome by coexpression of NS5A. siRNA-mediated knockdown of FBL2 mRNA by 70% in Huh7-HP cells reduced HCV RNA by 65%; this reduction was overcome by expression of a cDNA encoding a wobble mutant of FBL2. The current data indicate that geranylgeranylated FBL2 binds to NS5A in a reaction crucial for HCV RNA replication.

Cell Cycle Proteins↗
PubMed2005

[Effect of puerarin on the expression of Hsp70 in the rats with cerebral injury induced by acute local ischemia].

OBJECTIVE: To study the effect of puerarin on the expression of Hsp (heat shock protein) 70 in the rats with cerebral injury induced by acute local ischemia. METHOD: Rat model of acute local cerebral ischemia was made by ligating middle cerebral artery. The Hsp70 expression in brain tissue was detected by SP method of immunohistochemistry. RESULT: The expression of Hsp70 was significantly higher in puerarintreated rats than those in the rats with cerebral ischemia. CONCLUSION: Puerarin can enhance the level of Hsp70 expression in the rats with cerebral injury induced by acute local ischemia.

Animals↗
PubMed2005

[Study on purification of total peony glycoside with D140 macroporous resin].

OBJECTIVE: To study the extraction process of total peony glycoside from Paeonia veitchii Lynvh. METHODS: The extraction process of total peony glycoside with D140 macroporous resin adsorbent was selected with different condence of ethanol for gradient elution. RESULTS: The optimum condence was 35% ethanol. CONCLUSION: The extraction ratio of paeoniflorin was >50%, and the extraction process is simple and convenient. The regenaration of resin is easy, this method is advisible.

Chromatography, High Pressure Liquid↗
PubMed2005

[Detection of glucocorticoid receptor-alpha mRNA expression using FQ-RT-PCR in nasal polyp].

OBJECTIVE: To detect the expression of the glucocorticoid receptor-alpha (GR-alpha) mRNA in nasal polyp and normal nasal mucosa and investigate the significance of GR-alpha in progression of nasal polyp. METHOD: The expression of GR-alpha mRNA in 36 samples of nasal polyp and 31 samples of normal nasal mucosa was examined by using fluorescent quantitative PCR(FQ RT-PCR). RESULT: The GR-alpha mRNA levels in normal nasal mucosa [(135.4 +/- 5.2) x 10(10) copy/g] were significantly higher than those in nasal polyp [(25.5 +/- 5.0) x 10(10) copy/g] (P < 0.01). CONCLUSION: The low expression of GR-alpha mRNA in nasal polyp is related to the progression of nasal polyp.

Adult↗
PubMed2004

Proteolytic activation of sterol regulatory element-binding protein induced by cellular stress through depletion of Insig-1.

Insig-1 and Insig-2 are closely related proteins of the endoplasmic reticulum (ER) that block proteolytic activation of sterol regulatory element-binding proteins (SREBPs), membrane-bound transcription factors that activate synthesis of cholesterol and fatty acids in animal cells. When cellular cholesterol levels are high, Insig proteins bind to SREBP cleavage-activating protein, retaining it in the ER and preventing it from escorting SREBPs to the site of proteolytic activation in the Golgi complex. Here we report that hypotonic stress reverses the sterol-mediated inhibition of SREBP proteolytic activation by reducing the level of Insig-1 but not Insig-2. The reduction of Insig-1, a protein with a rapid turnover rate, results from a general inhibition of protein synthesis mediated by hypotonic stress. Insig-2 is not affected by hypotonic stress because of its slower turnover rate. Inhibition of protein synthesis by hypotonic shock has not been reported previously. Thapsigargin, an activator of the ER stress response, also inhibits protein synthesis and activates proteolysis of SREBP. Such activation also correlates with the disappearance of Insig-1. The current study demonstrates that animal cells, in response to either hypotonic shock or ER stress, can bypass the cholesterol inhibition of SREBP processing, an effect that is attributable to the rapid turnover of Insig-1.

Animals↗
PubMed2004

How cholesterol homeostasis is regulated by plasma membrane cholesterol in excess of phospholipids.

How do cells sense and control their cholesterol levels? Whereas most of the cell cholesterol is located in the plasma membrane, the effectors of its abundance are regulated by a small pool of cholesterol in the endoplasmic reticulum (ER). The size of the ER compartment responds rapidly and dramatically to small changes in plasma membrane cholesterol around the normal level. Consequently, increasing plasma membrane cholesterol in vivo from just below to just above the basal level evoked an acute (<2 h) and profound ( approximately 20-fold) decrease in ER 3-hydroxy-3-methylglutaryl-CoA reductase activity in vitro. We tested the hypothesis that the sharply inflected ER response to cholesterol is governed by the thermodynamic activity (fugacity) of plasma membrane cholesterol. The following two independent measures of plasma membrane cholesterol activity in human red cells and fibroblasts were used: susceptibility to cholesterol oxidase and cholesterol transfer to cyclodextrin. Both indicators revealed a threshold at the physiologic set point of plasma membrane cholesterol. Incrementing the phospholipid compartment in the plasma membrane with lysophosphatidylcholine, previously shown to decrease cholesterol oxidase susceptibility, reduced the transfer of plasma membrane cholesterol to cyclodextrin and to the ER. Conversely, the membrane intercalator, n-octanol, increased cholesterol oxidation, transfer, and ER pool size, perhaps by displacing cholesterol from plasma membrane phospholipids. We conclude that the activity of the fraction of cholesterol in excess of other plasma membrane lipids sets the cholesterol level in the ER. Cholesterol-sensitive elements therein respond by nulling the active plasma membrane pool, thereby keeping the cholesterol matched to the other plasma membrane lipids.

Biological Transport↗
PubMed2004

[The effect of all-trans retinoid acid and sodium selenite (Na2SeO3) on VEGF and its receptor expression in HL-60 cells].

In order to investigate the effect of non-medullar toxicity drug - all trans retinoid acid (ATRA) and cancer preventive trace element-selenium compound - sodium selenite (Na(2)SeO(3)) on the expression of vascular endothelial growth factor (VEGF) and its receptor in HL-60 cells, the expression of VEGF and its receptor in HL-60 cells were detected by ELISA technique and flow cytometry before and after treatment with two drugs. The results showed that the mean VEGF concentrations in the cultural supernatant of 5 and 10 micro mol/L ATRA-treated HL-60 cells for 48 and 72 hours were lower than those of the control group without adding ATRA. The differences between the ATRA-treated groups and the control group were statistically significant (P = 0.001, P = 0.000, P < 0.01, respectively). The levels of VEGF-R on the surface of HL-60 cells also decreased after treatment with ATRA of 5 and 10 micro mol/L for 72 hours, but at 48 hours the expression rates of VEGF-R on HL-60 cells of the two ATRA treated groups were not significantly decreased. At 48 and 72 hours, Na(2)SeO(3) of 5 and 10 micro mol/L had no obvious effect on HL-60 secreting VEGF, but notablely inhibited the expression of VEGF-R. In conclusion, ATRA could inhibit the expression of VEGF and its receptor in HL-60 cell. Na(2)SeO(3) could not inhibit the expression of VEGF in HL-60 cell, but could decrease the receptor expression of VEGF, which mechanism should be further studied. ATRA and Na(2)SeO(3) had not obvious medullar-inhibition, but anti-angiogenesis activity. It is suggested that combination of two drugs with conventional therapy may enhance the effect of radiotherapy and chemotherapy, and reduce the dose and thus toxicity of chemotherapeutic agents.

Dose-Response Relationship, Drug↗
PubMed2004

[Computer tomography characteristics of chronic invasive fungal rhinosinusitis in early stage].

OBJECTIVE: To discuss the computer tomography (CT) characteristics of chronic invasive fungal rhinosinusitis in early stage and their diagnostic value. METHOD: The CT characteristics of 18 cases of chronic invasive fungal rhinosinusitis in early stage and 35 noninvasive fungal rhinosinusitis diagnosed with pathologic examination were retrospectively analyzed and compared. RESULT: On sinus CT scan of chronic invasive fungal rhinosinusitis in early stage, 78% (14/18) were single-sinus lesioned. The maxillary sinus was the most commonly lesioned sinus, followed by the sphenoid sinus and ethmoid sinus. 22% (4/18) were poly-sinus lesioned. All infected sinus showed complete or subtotal heterogeneous opacity. In 62% (12/18) cases the lesion expanded into the adjacent sinus or nasal cavity. 78%(14/18)had calcification spots or points (CT number between 80 Hu and 160 Hu) in the soft tissue window. Bony destruction occurred in 6 cases (33%), in which lamina papyracea and middle turbinates were mostly destructed simultaneously each in 2 cases. Chronic invasive fungal rhinosinusitis had more poly-sinus lesioned cases and bony destructed cases than noninvasive fungal rhinosinusitis and its bone lesion degree was higher too. CONCLUSION: Chronic invasive fungal rhinosinusitis in early stage has more poly-sinus lesioned cases and higher bony destruction ratio and degree. But its total CT characteristics are similar with noninvasive fungal rhinosinusitis. So sinus CT scan has no specific meaning in diagnosing of chronic invasive rhinosinusitis in early stage.

Adult↗
PubMed2003

Disruption of hepatitis C virus RNA replication through inhibition of host protein geranylgeranylation.

Hepatitis C virus (HCV) RNA replication depends on viral protein association with intracellular membranes, but the influence of membrane composition on viral replication is unclear. We report that HCV RNA replication and assembly of the viral replication complex require geranylgeranylation of one or more host proteins. In cultured hepatoma cells, HCV RNA replication was disrupted by treatment with lovastatin, an inhibitor of 3-hydroxy-3-methyglutaryl CoA reductase, or with an inhibitor of protein geranylgeranyl transferase I, each of which induced the dissolution of the HCV replication complex. Viral replication was not affected by treatment of cells with an inhibitor of farnesyl transferase. When added to lovastatin-treated cells, geranylgeraniol, but not farnesol, restored replication complex assembly and viral replication. Inasmuch as the HCV genome does not encode a canonical geranylgeranylated protein, the data suggest the involvement of a geranylgeranylated host protein in HCV replication. Inhibition of its geranylgeranylation affords a therapeutic strategy for treatment of HCV infection.

Antiviral Agents↗
PubMed2003

[A clinical study on improving phonation function of larynx after partial laryngectomy].

OBJECTIVE: To analyse the clinical results of reconstruction of vocal cord using sternohyoid muscle flap after partial laryngectomy and research a new repairing method to improve laryngeal function and living quality of patient. METHOD: The pronunciation of larynx is on the basic of the vibration of the vocal cord by air current. The laryngeal appearance and the function of opposite side vocal cord is very important for improving the quality of pronunciation. We developed a technique of thyroid cartilage membrane and sternohyoid muscle flap to repair the defect left by a vertical laryngectomy and reconstructed the vocal cord. The thyroid cartilage membrane was used to bridge over the upper part defect of laryngeal cavity, the sternohyoid muscle flap forming the opposite side was made a 90 degree bent toward the laryngeal cavity to repaired the lower part defect of laryngeal cavity and reconstruct a new vocal cord. The repaired larynx recovered the normal appearance. The new vocal cord participated speech. The anterior 2/3 part of both vocal cored could contacted in pronunciation of patient. The phonation function of larynx was restored. RESULT: Sixty-one cases partial laryngectomy was taken including vertical partial laryngectomy in 37 cases, extended vertical partial laryngectomy in 24. During their operations, the laryngeal defect was repaired with thyroid cartilage membrane and sternohyoid muscle flap, and a vocal cord was reconstructed in the same time. After operation, the laryngeal cavity repaired has a normal appearance, and the laryngeal satisfactory phonation effect has been obtained. 93.4% of the patients enjoyed a socially acceptable voice and rejoined normal working. CONCLUSION: A technique of thyroid cartilage and sternohyoid muscle flap to repair the defect and reconstructive vocal cord after partial laryngectomy make patient recover normal laryngeal appearance and obtain satisfactory phonation effect. Among the method of repairation for partial laryngectomy sternohyoid muscle flap should be first considered owing to its various merits: 1. abundant material. 2. convenient procedures. 3. smaller trauma. 4. satisfactory effect.

Adult↗
PubMed2003

[The expression of vascular endothelial growth factor and its receptor in hematopoietic malignant cell lines HL-60 and Raji].

In order to explore the effect of vascular endothelial growth factor (VEGF) in hematological malignancies, the expression of VEGF and its receptor was detected in HL-60 and Raji cells by reverse transcriptase-polymerase chain reaction (RT-PCR), enzyme linked immunosorbent assay (ELISA) and immunohistochemistry. The results showed that VEGF-mRNA expressed in both HL-60 and Raji cells, and the mean VEGF concentrations in the cultural supernatant of both cell lines were significantly higher than that of normal peripheral blood mononuclear cell respectively. There was expression of VEGF-R (Flt-1) on the surfaces of both HL-60 and Raji cells. The research results demonstrated that VEGF-mRNA was expressed in hematopoietic malignant cell lines (HL-60 and Raji), and the corresponding protein was secreted into the extracellular microenvironment, the both cell lines expressed VEGF-R on the cell surface. VEGF affects not only vascular endothelial cells, but also leukemic and lymphoma cells themselves. It is suggested that an autocrine pathway of VEGF existed in the both cell lines other than the paracrine pathway. The autocrine pathway of VEGF works as basis of tumor invasion. In conclusion, to restrain expression of VEGF and its receptor may inhibit tumor growth, and helps to block the reciprocal loop between VEGF and endothelial cells, and decrease the tumor specialities of hyperproliferation, anti-apoptosis and invation, that may make the tumor more susceptible to chemotherapy.

Enzyme-Linked Immunosorbent Assay↗