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Biomedical subjects

Wei Liu

Publications and source records attributed to Wei Liu.

At least 289 records · Page 16Linked to original sources
PubMed2004

Tissue engineering of cartilage with the use of chitosan-gelatin complex scaffolds.

Chitosan has been shown to be a promising scaffold for various applications in tissue engineering. In this study, a chitosan-gelatin complex was fabricated as a scaffold by a freezing and lyophilizing technique. Chitosan's structure and characteristics are similar to those of glycosaminoglycan (GAG) and its analogs, and possesses various biological activities, whereas gelatin can serve as a substrate for cell adhesion, differentiation, and proliferation. With the use of autologous chondrocytes isolated from pig's auricular cartilage and seeded onto the chitosan-gelatin scaffold, elastic cartilages have been successfully engineered at the porcine abdomen subcutaneous tissue. After 16 weeks of implantation, the engineered elastic cartilages have acquired not only normal histological and biochemical, but also mechanical properties. The tissue sections of the engineered elastic cartilages showed that the chondrocytes were enclosed in the lacuna, similar to that of native cartilage. The presence of elastic fibers in the engineered cartilages was also demonstrated by Vehoeff's staining, and immunohistochemical staining confirmed the presence of type II collagen in the engineered cartilages. Quantitatively, the GAG in the engineered cartilages reached 90% of the concentration in native auricular cartilage. Furthermore, biomechanical analysis demonstrated that the extrinsic stiffness of the engineered cartilages reached 85% of the level in native auricular cartilage when it was harvested at 16 weeks. Thus, this study demonstrated that the chitosan-gelatin complex may serve as a suitable scaffold for cartilage tissue engineering.

Animals↗
PubMed2004

[Multicenter, randomized, positive-controlled clinical study for the effects of nerotropin on diabetic neuropathy].

OBJECTIVE: To estimate the effects of Neurotropin in the treatment of neuralgia and numbness in type 2 diabetes mellitus patients with diabetic peripheral neuropathy (DPN), and compare with Methycobal. METHODS: Ninety-five patients with DPN from 4 hospitals in shanghai were randomly assigned to two groups: 49 cases in Neurotropin group (6 ml, IV, QD for 2 weeks, then, 2 tablets, BID for another 2 weeks). 46 cases in Methycobal group (1 ml, IM, QD for 2 weeks, then, 1 tablet TID for another 2 weeks. RESULTS: Neurotropin significantly improved neuralgia in type 2 diabetes mellitus with DPN, the efficacy rate was 67.3% in the first week, and 87.0% in the 4th week, comparing with 34.8% and 68.5% in the control group. The efficacy rate for numbness was 58.7% in the study group after 4 weeks therapy, and 69.5% in control group. In the whole 4 weeks therapeutic course, neuralgia and numbness were improved in the two groups, and the improved rate in Neurotropin group is high than in the control group (P < 0.01). CONCLUSION: Neurotropin had good effects in the treatment of diabetic neuralgia and numbness, the efficacy of Neurotropin in improving the senses of neuralgia is better than Methecobal., and similar with Methecobal in treating numbness.

Aged↗
PubMed2004

MAPKAP kinase-2 is a primary response gene induced by depolarization in PC12 cells and in brain.

Using a combination of targeted differential display for induced protein kinases and differential library screening, we identified mitogen-activated protein kinase activated protein kinase 2 (MAPKAPK2), as a primary response gene whose transcription is stimulated by membrane depolarization and by forskolin in rat PC12 pheochromocytoma cells. MAPKAPK3 was neither induced nor repressed by similar treatments. The increase in MAPKAPK2 mRNA is preceded by an increase in a MAPKAPK2 intron-containing RNA precursor, indicating that the increase in message is due at least in part to increased transcription. The open reading frame of full-length rat MAPKAPK2 cDNA is 99% identical to mouse MAPKAPK2 and 92% identical to human MAPKAPK2. The human MAPKAPK2 predicted protein contains 14 additional amino acids in the proline-rich N-terminal domain, when compared to murine and rat MAPKAPK2 predicted proteins. The MAPKAPK2 form found in PC12 cells corresponds to variant 2 in the human; this ortholog carries a nuclear translocation signal near its C-terminus. MAPKAPK2 message is also induced in the dentate gyrus, CA1, and CA3 of the rat hippocampus between 2-4 hr after the onset of kainic acid-induced seizures.

Amino Acid Sequence↗
PubMed2004

New electrocardiographic criteria for identifying the culprit artery in inferior wall acute myocardial infarction-usefulness of T-wave amplitude ratio in leads II/III and T-wave polarity in the right V5 lead.

ST-segment elevations in the right ventricular lead and those greater in lead III than in lead II strongly suggest that right, rather than left circumflex, coronary arterial occlusion occurs in acute myocardial infarction in the inferior wall. Our study demonstrated that, in the very early stages of infarction, a T-wave amplitude that is greater in lead III than in lead II and an upright or positive biphasic T wave in lead V(5)R are just as predictive as ST-segment changes and are often easier to measure.

Arteries↗
PubMed2004

[Experimental study of in vitro chondrogenesis by co-culture of bone marrow stromal cells and chondrocytes].

OBJECTIVE: Chondrogenic microenvironments play a very important role in chondrogenesis of bone marrow stromal cells (BMSC). This study explored the feasibility of in vitro chondrogenesis by co-culture of BMSC and chondrocytes so as to confirm the hypothesis that chondrocytes can provide chondrogenic microenvironment to induce chondrogenic differentiation of BMSC and thus promote in vitro chondrogenesis of BMSC. METHODS: Porcine BMSC and auricular chondrocytes were in vitro expanded respectively and then were mixed at a ratio of 8:2 (BMSC:chondrocyte). 200 microl mixed cells(5.0 x 10(7)/ml) were seeded onto a polyglycolic acid/polylactic acid (PGA/PLA) scaffold, 9 mm in diameter and 3 mm in thickness, as co-culture group. Chondrocytes and BMSC with the same cell number were seeded respectively onto the scaffolds as positive control (chondrocyte group) and negative control (BMSC group). 200 microl chondrocytes (1.0 x 10(7)/ml, equal to the chondrocyte number of co-culture group) alone were seeded as low concentration chondrocyte group. There were 6 specimens in each group. All specimens were harvested after in vitro culture for 8 weeks in DMEM plus 10% FBS. Gross observation, average wet weight measurement, glycosaminoglycan (GAG) quantification, histology and immunohistochemistry were used to evaluate the results. RESULTS: Cells in all groups had fine adhesion to the scaffolds and could secrete extracellular matrix. In both co-culture group and positive control group, the cell-scaffold constructs could maintain the original size and shape during in vitro culture and formed homogenous mature cartilage after 8 weeks of in vitro culture. Furthermore, the neo-cartilages in both groups were similar to each other in gross appearance and histological features, and abundant type II collagen was also detected by immunohistochemistry in both groups. The average wet weight and GAG content of co-culture group were both more than 80% of those of positive control group. In negative control group, however, the constructs shrunk gradually during in vitro culture and cartilage-like tissue could only be observed at the edge area of the construct. In low concentration chondrocyte group, the constructs also shrunk gradually during in vitro culture and the average wet weight was below 40% of that of the positive control group although histology showed a small amount cartilage formation. CONCLUSION: Chondrocytes can provide a chondrogenic microenvironment to induce a chondrogenic differentiation of BMSC and thus promote the in vitro chondrogenesis of BMSC.

Animals↗
PubMed2004

Functional identification of three receptor activator of NF-kappa B cytoplasmic motifs mediating osteoclast differentiation and function.

Receptor activator of NF-kappa B ligand (RANKL) and its receptor activator of NF-kappa B (RANK) play pivotal roles in osteoclast differentiation and function. However, the structural determinants of the RANK that mediate osteoclast formation and function have not been definitively identified. To address this issue, we developed a chimeric receptor approach that permits a structure/function study of the RANK cytoplasmic domain in osteoclasts. Using this approach, we examined the role of six RANK putative tumor necrosis factor receptor-associated factor-binding motifs (PTM) (PTM1, ILLMT-REE(286-293); PTM2, PSQPS(349-353); PTM3, PFQEP(369-373); PTM4, VYVSQTSQE(537-545); PTM5, PVQEET(559-564); and PTM6, PVQEQG(604-609)) in osteoclast formation and function. Our data revealed that the RANK cytoplasmic domain possesses three functional motifs (PFQEP(369-373), PVQEET(559-564), and PVQEQG(604-609)) capable of mediating osteoclast formation and function. Moreover, we demonstrated that these motifs play distinct roles in activating intracellular signaling. PFQEP(369-373) initiates NF-kappa B, c-Jun N-terminal kinase, extracellular signal-regulated kinase, and p38 signaling pathways and PVQEET(559-564) activates NF-kappa B and p38 pathways in osteoclasts, whereas PVQEQG(604-609) is only capable of activating NF-kappa B pathway. Significantly, the revelation of these functional RANK cytoplasmic motifs has not only laid a foundation for further delineating RANK signaling pathways in osteoclasts, but, more importantly, these RANK motifs themselves represent potential therapeutic targets for bone disorders such as osteoporosis.

Amino Acid Sequence↗
PubMed2004

Differential expression of divalent metal transporter DMT1 (Slc11a2) in the spermatogenic epithelium of the developing and adult rat testis.

Iron is essential for male fertility, and disruptions in iron balance lead to impairment of testicular function. The divalent metal transporter DMT1 is a key modulator of transferrin- and non-transferrin-bound iron homeostasis. As a first step in determining the role of DMT1 in the testis, we have characterized the pattern of DMT1 expression in the developing and adult rat testis. Northern blot analysis and RT-PCR of testis polyadenylated RNA revealed the presence of iron-responsive element (IRE) and non-IRE transcripts. Semiquantitative immunoblotting of immature and adult rat testis uncovered the expression of two distinct DMT1 protein species. Immunohistochemistry showed that DMT1 was widespread throughout each seminiferous tubule and was expressed in the intracellular compartment. In the adult rat testis, DMT1 was immunolocalized to both the Sertoli and germ cells. In contrast to the immature testis, expression was dependent on the stage of the spermatogenic cycle. DMT1 was not detected on any plasma membranes in either the developing or the adult testis, suggesting that DMT1 is not primarily responsible for translocating iron across this epithelium. Our data suggest an important role for DMT1 in intracellular iron handling during spermatogenesis and imply that germ cells have a need for a precisely targeted and timed supply of iron. We suggest that DMT1 may, as it does in other tissues, play a role in transporting iron between intracellular compartments and thus may play an important role in male fertility.

Age Factors↗
PubMed2004

Darbepoetin alfa effectively treats anemia in patients with chronic kidney disease with de novo every-other-week administration.

AIM: This multicenter, open-label study determined safety and efficacy of once-every-other-week administration of darbepoetin alfa for anemia of chronic kidney disease in erythropoietin-naive patients not on dialysis. METHODS: Participants with hemoglobin levels <11.0 g/dl at baseline were administered darbepoetin alfa at an initial dosage of 0.75 microg/kg once every other week. The dose was titrated to achieve and maintain a hemoglobin response, defined as a hemoglobin range of between 11.0 and 13.0 g/dl for up to 24 weeks. The primary end point was the dose of darbepoetin alfa at initial hemoglobin response. RESULTS: Six hundred and eight patients were enrolled, and 463 completed the study; 95% (95% confidence interval: 0.93, 0.97) of the patients who completed treatment achieved a hemoglobin response. The mean darbepoetin alfa dose at the time of response was 63.5 +/- (SD) 16.9 microg, and the mean time to hemoglobin response was 5.7 +/- (SD) 4.5 weeks. Oral iron therapy was administered to 60% and intravenous iron to 16% of the participants. Darbepoetin alfa was well tolerated, and adverse events were consistent with those expected in patients with chronic kidney disease. CONCLUSION: Darbepoetin alfa administered once every other week is effective and safe for achieving and maintaining target hemoglobin levels in anemic patients with chronic kidney disease.

Adult↗
PubMed2004

Vitamin D3 administration induces nuclear p27 accumulation, restores differentiation, and reduces tumor burden in a mouse model of metastatic follicular thyroid cancer.

We have previously demonstrated in vitro that 1alpha,25-dihydroxyvitamin D3 (calcitriol) treatment increases p27 expression and decreases cell proliferation in cultured thyroid carcinoma cell lines. We hypothesized that in vivo treatment with calcitriol would have a beneficial effect on thyroid carcinoma growth and progression. Five x 10(6) WRO (human thyroid follicular carcinoma derived) cells were implanted in the neck in 4- to 5-wk-old female SCID mice in an orthotopic xenograft model. Animals (n = 15) were treated i.p. three times a week for 21 d with 0.75 microg/kg calcitriol or vehicle. Mice were killed 21 d after tumor implantation, tumor volume was measured, and excised tumor tissue was examined by light microscopy and immunohistochemistry for p27 and thyroglobulin reactivity. Average tumor volume in control mice after 21 d of vehicle treatment was 2002 +/- 207 mm3 compared with a mean tumor volume of 1241 +/- 115 mm3 in animals receiving calcitriol, reflecting a 38% reduction in tumor volume size (P < 0.003). Tumors from vehicle-treated animals demonstrated morphological features of epithelial malignancies with characteristics of insular carcinoma and multiple metastases to the lungs. Tumors excised from calcitriol-treated animals demonstrated signs of differentiation with restoration of thyroglobulin staining. This was associated with a marked accumulation of p27 immunoreactivity in the nuclear compartment. These studies demonstrate that in vivo calcitriol administration can effectively restore p27 accumulation in thyroid carcinoma cells, an effect associated with appreciably enhanced cellular differentiation, reduction in tumor burden, and prevention of metastatic growth.

Adenocarcinoma, Follicular↗
PubMed2004

A new zincoborophosphate templated by diethylenetriamine (DETA): synthesis and characterizations of (C4N3H16)-[Zn3B3P6O24].H2O.

The title zincoborophosphate was synthesized hydrothermally from a mixture of ZnO, B2O3, H3PO4 and the structure-directing amine, DETA. Its crystal structure contains helices made up of corner-sharing BO4 and PO4 tetrahedra, which interconnected with ZnO4 tetrahedra to form a three dimensional structure with the CZP topology. The amine and water molecules occupy the free thread of the helices and the center of the channels, respectively. Thermal stability investigations show that this new compound can be dehydrated at 423 K and the product is stable up to 723 K. Furthermore, the as-synthesized title compound and its dehydration product are luminescent, each with a similar broad band between 350 and 550 nm, but the emission of the latter is about three times more intense than that of the former.

Journal Article↗
PubMed2004

[Cartilage-derived morphogenetic protein 1 initiates chondrogenic differentiation of human dermal fibroblasts in vitro].

OBJECTIVE: To investigate the feasibility of human dermal fibroblasts in vitro differentiation into chondrogenic phenotype with induction of cartilage-derived morphogenetic protein (CDMP) growth factor. METHODS: Human dermal fibroblasts were isolated from foreskin and cultured in monolayer ex vivo. Dermal fibroblasts of passage2 was plated at density of 1 x 10(4) cells/cm(2) and induced with CDMP1 (100 ng/ml) in medium of F12 + 10% FBS. After 7 days of induction, morphology of cells was observed under phase-contrast microscopy and the length:width ratio of cells was calculated by Image Plus software analysis. Expression of type I, II, III collagen was detected by immunofluorescence and observed with confocal microscopy. The method of Western-Blot was applied to detect secretion of collagen type II. mRNA expression of chondrogenic related Sox9, Aggrecan as well as collagen type II, IX was detected by RT-PCR. The osteogenic related expression of collagen type X, Alkaline Phosphatase (AKP) was also detected by RT-PCR. Pellet cultured dermal fibroblasts at a density of 2 x 10(7) cells/ml was observed respectively for proteoglycan and collagen type II expression with Alcian blue and immunohistochemistry staining. RESULTS: With the induction of CDMP1, the morphology of cells changed from spindle fibroblastic appearance to that of typical chondrocyte-like polygon shape. By Image Plus software analysis, it was found that the length/width ratio changed significantly from 7.40 +/- 1.30 of preinduction to 1.40 +/- 0.15 of post-induction (P < 0.05). No significant difference was found between the postinduction and normal chondrocyte (1.29 +/- 0.24). By confocal microscope observation, expression of collagen type II was found intracellularly in CDMP1 treated fibroblasts. Western-Blot detection confirmed collagen type II expression by 7 days induction. RT-PCR gene expression analysis of characteristic chondrogenic related genes, such as Sox9, Aggrecan as well as collagen type II, IX, revealed induction of chondrocytic phenotype in monolayered culture upon stimulation with CDMP1 for 7 days. While osteogenic related gene expression of collagen type X, AKP was not detected by RT-PCR, which indicates that osteogenic differentiation was not initiated by CDMP1 in 7 days culture. Histological staining of proteoglycan with Alcian blue and immunohistochemical staining cartilage specific type II collagen revealed deposition of typical cartilage extracellular matrix deposition in pellet cultured fibroblasts. CONCLUSION: These results suggests human dermal derived fibroblast could be differentiated into chondrogenic phenotype with CDMP1 induction in vitro.

Adolescent↗
PubMed2004

Multiple gene differential expression patterns in human ischemic liver: safe limit of warm ischemic time.

AIM: To investigate the multiple gene differential expression patterns in human ischemic liver and to produce the evidence about the hepatic ischemic safety time. METHODS: The responses of cells to hepatic ischemia and hypoxia at hepatic ischemia were analyzed by cDNA microarrary representing 4 000 different human genes containing 200 apoptotic correlative genes. RESULTS: There were lower or normal expression levels of apoptotic correlative genes during the periods of hepatic ischemia for 0-15 min, the maintenance homostatic genes were expressed significantly higher at the same time. But at the hepatic ischemia for 30 min, the expression levels of maintenance homeostatic genes were down-regulated, the expressions of many apoptotic correlative genes and nuclear transcription factors were activated and up-regulated. CONCLUSION: HIF-1, APAF-1, PCDC10, FBX5, DFF40, DFFA XIAP, survivin may be regarded as the signal genes to judge the degree of hepatic ischemic-hypoxic injure, and the apoptotic liver cell injury due to ischemia in different time limits. The safe limit of human hepatic warm ischemic time appears to be generally less then 30 min.

Down-Regulation↗
PubMed2004

Quantification of stenotic mitral valve area with magnetic resonance imaging and comparison with Doppler ultrasound.

OBJECTIVES: The purpose of this study was to evaluate the reliability of the pressure half-time (PHT) method for estimating mitral valve areas (MVAs) by velocity-encoded cardiovascular magnetic resonance (VE-CMR) and to compare the method with paired Doppler ultrasound. BACKGROUND: The pressure half-time Doppler echocardiography method is a practical technique for clinical evaluation of mitral stenosis. As CMR continues evolving as a routine clinical tool, its use for estimating MVA requires thorough evaluation. METHODS: Seventeen patients with mitral stenosis underwent echocardiography and CMR. Using VE-CMR, MVA was estimated by PHT method. Additionally, peak E and peak A velocities were defined. Interobserver repeatability of VE-CMR was evaluated. RESULTS: By Doppler, MVAs ranged from 0.87 to 4.49 cm2; by CMR, 0.91 to 2.70 cm2, correlating well between modalities (r = 0.86). The correlation coefficient for peak E and peak A between modalities was 0.81 and 0.89, respectively. Velocity-encoded CMR data analysis provided robust, repeatable estimates of peak E, peak A, and MVA (r = 0.99, 0.99, and 0.96, respectively). CONCLUSIONS: Velocity-encoded cardiovascular magnetic resonance can be used routinely as a robust tool to quantify MVA via mitral flow velocity analysis with PHT method.

Aged↗
PubMed2004

[Surgical treatment of gliomas involving the supplementary motor area in the superior frontal gyrus].

OBJECTIVE: To explore surgical treatment of gliomas involving the supplementary motor area (SMA) in the superior frontal gyrus. METHODS: Clinical data and follow-up outcome of 16 patients with low graded astrocytomas involving the supplementary motor area were analyzed. RESULTS: SMA syndrome was developed in 6 patients in whom the posterior tumor resection line was at a distance of more than 1 cm from the precentral sulcus and resolved after 12 months. Hemiplegia occurred however in 8 patients in whom the resection line was less than 1 cm to precentral sulcus and only resolved in 3 patients during follow period 12 months. CONCLUSIONS: When the resection is performed at a distance of less than 1 cm from the precentral sulcus, surgery for gliomas of involving the supplementary motor area in the superior frontal gyrus may be result in permanent morbidity.

Adult↗
PubMed2004

Hydrothermal synthesis and characterization of two organically templated cadmium borophosphates with novel structures.

Two organically templated cadmium borophosphates, (C(4)H(16)N(3))[CdClB(2)P(3)O(12)(OH)] (1) and (C(2)H(10)N(2))[CdB(2)P(3)O(12)(OH)] (2), were synthesized hydrothermally in the presence of structure-directing amines. Compound 1 has a complex layered structure (orthorhombic, Pbca (No. 61); a = 9.470(2), b = 12.307(3), c = 27.311(6) A; V = 3183 (1) A(3); Z = 8) with a 9MR channel system, while compound 2 (orthorhombic, Pbca (No. 61); a = 9.286(3), b = 12.459(3), c = 21.626(6) A; V = 2502(1) A(3); Z = 8) presents a 3-dimensional open framework structure of different types of intersecting channels. It is worth noting that both the Cl(-) anions and the organic templates play important and interesting roles in the formation of the structures.

Journal Article↗
PubMed2004

[Repairing porcine knee joint osteochondral defects at non-weight bearing area by autologous BMSC].

OBJECTIVE: To test the possibility of using bone marrow stromal cells (BMSC) and biodegradable polymers to repair articular osteochondral defects at non-weight bearing area of porcine knee joints. METHODS: Bone marrows were harvested from 18 hybrid pigs. BMSC were cultured and in vitro expanded and induced with dexamethasone (group A) or with dexamethasone and transforming growth factor-beta1 (TGF-beta1) (group B) respectively. Immunohistochemistry and RT-PCR were used to evaluate chondrogenic differentiation of induced cells. Part of BMSC of 2 animals were retrovirally-labeled with green fluorescent protein (GFP). After induction and label, cells were seeded on a construct of polyglycolic acid (PGA) and polylactic acid (PLA) and co-cultured for 1 week before implantation. Total 4 osteochondral defects (8 mm in diameter, 5 mm in depth) in each animal were created at the non-weight bearing areas of knee joints on both sides. The defects were repaired with dexamethasone induced BMSC-PGA/PLA construct in group A, with dexamethasone and TGF-beta1 induced BMSC-PGA/PLA construct in group B, with PGA/PLA construct alone (group C) or left untreated (group D) as controls. Animals were sacrificed at 3 months (n = 6) or 6 months (n = 10) post-repair. Gross observation, histology, glycosaminoglycan (GAG) quantification and biomechanical test were applied to analyze the results. The two animals with GFP-labeled cells were sacrificed at 7 months post-repair to observe with confocal microscope the distribution of GFP-labeled cells in repaired tissue. RESULTS: Stronger expression of type II collagen and aggrecan were observed in BMSCs induced with both dexamethasone and TGF-beta1. At both time points, Gross observation and histology showed that the defects in most of group A were repaired by engineered fibrocartilage and cancellous bone with an irregular surface, minority defects were repaired by engineered hyaline cartilage and cancellous bone. However, in most of group B, the defects were completely repaired by engineered hyaline cartilage and cancellous bone. No repair or only fibrous tissue were observed in groups C and D. Besides, the compressive moduli of repaired cartilage in groups A and B reached 30.37% and 43.82% of normal amount at 3 months and 62.69% and 80.27% at 6 months respectively, which was further supported by the high levels of GAG contents in engineered cartilage of group A (78.03% of normal contents) and group B (no statistical difference from normal contents). More importantly, confocal microscope revealed the presence of GFP-labeled cells in engineered cartilage lacuna and repaired underlying cancellous bone. CONCLUSION: The results demonstrated that implanted BMSC can differentiate into either chondrocytes or osteoblasts at different local environments and repair a complex articular defect with both engineered cartilage and bone. TGF-beta1 and dexamethasone in vitro induction can promote chondrogenic differentiation of BMSC and thus improve the results of repairing articular defects.

Animals↗
PubMed2004

Synaptotagmin IV overexpression inhibits depolarization-induced exocytosis in PC12 cells.

Depolarization-induced vesicle exocytosis is a complex mechanism involving a number of proteins. In this process, synaptotagmins work as members of the Ca(2+)-sensing system that triggers the fusion of the synaptic vesicle with the plasma membrane. Synaptotagmin IV (SytIV), an immediate-early gene induced by depolarization in PC12 pheochromocytoma cells and in the hippocampus, has been suggested to work as a negative regulator of neurotransmitter release. Unlike other synaptotagmins, SytIV has an evolutionarily conserved substitution of an aspartate to a serine in the Ca(2+) coordination site of its C2A domain, preventing SytIV from binding anionic lipids in a Ca(2+)-dependent fashion. We used the secretion of human growth hormone (hGH) as a reporter system with which to examine the effects of overexpressing SytIV and other depolarization-induced immediate-early genes (the protein kinases KID-1, SIK, and PIM-1 and the transcription factors rTLE3 and Nurr1) on depolarization-induced vesicle exocytosis in PC12 cells. SytIV overexpression resulted in decreased depolarization-induced hGH release. However, conversion of the unique serine in SytIV to an aspartate eliminated this inhibitory activity. In addition, rTLE3 overexpression produced only a modest increase in spontaneous vesicle exocytosis, whereas KID-1, SIK, PIM-1, and Nurr1 overexpression had no effect on depolarization-induced exocytosis.

Animals↗