Biomedical subjects

Jianbo Yang

Publications and source records attributed to Jianbo Yang.

10 recordsLinked to original sources

PubMed2006

The Amino-terminal domain of tntegrin beta3 functions as a transcriptional activator in yeast.

A deletion mutant encoding the integrin beta3(4I-F56) with an additional Gln at the carboxyl terminus was found occassionally when we were constructing a counterselection yeast two-hybrid assay modle. This mutant exhibited strong transcriptional activation in yeast cells, bearing the Escherichia coli lacZ reporter gene encoding the beta-galactosidase under the transcriptional control of GAL4 promoter and TATA box. Further analysis revealed that the region between the amino acid residues 23C to S77, an acidic domain involved in the function of several transcriptional activators were critical for optimal level of transactivation.

Amino Acid Sequence↗

PubMed2006

Extraction of biologic particles by pumping effect in a pi-shaped ultrasonic actuator.

This paper presents a new method of extracting biologic particles from a mixture of particles. The method is based on the pumping effect in a pi-shaped ultrasonic actuator, which has a gap between its two vibrating metal plates. An adhesive tape is placed at a proper position in the gap. Due to the pumping effect which is induced by the sound field in the gap, the particles with smaller mass and radius in the mixture can be pumped up to reach the adhesive tape; while the ones with larger mass cannot. Therefore, the particles with smaller mass and radius can be extracted from the mixture. A theoretical model which can well explain the operation principle and experimental phenomena is developed. By the experimental results and the theoretical analyses based on the model, the validity of the method in extracting small particles from a mixture of solid particles in air is confirmed, and the effects of the actuator's vibration, adhesive tape height, contents of the mixture and viscosity of fluid on the extraction are clarified. Also, it is theoretically predicted that the method will work under the microgravity condition in air.

Biopolymers↗

PubMed2006

Ultrasonic collection of small particles by a tapered metal strip.

A pi-shaped ultrasonic actuator can collect small particles by its two sharp edges. However, the collection of particles is weak in air and not very stable in water. In this paper, a refinement to the pi-shaped ultrasonic actuator is made for a more efficient collection of small particles in air and water. In the refined structure, an ultrasonic actuator with a metal strip is used to collect small particles. The metal strip is mechanically driven by one corner of a rectangular, sandwich-shaped ultrasonic transducer operating in the thickness mode vibration. The metal strip is tapered along its length and has a strong vibration at its tip. Small particles in air and water can be attracted to the radiation surface near the end of the metal strip. The dependence of the number of collected particles on driving frequency and voltage is investigated for shrimp eggs, mint seeds, and grass seeds. For a given driving voltage and particle type, the number of collected particles reaches a maximum value at some driving frequency. Increasing driving voltage increases this maximum number to some extent; but too large a driving voltage decreases it. The maximum number also depends on the weight per particle. It increases as the weight per particle decreases for the particles with close densities. Furthermore, the relationship between the number of collected particles and vibration amplitude at the end of the metal strip is investigated for shrimp eggs, mint seeds, and grass seeds. The number is approximately linearly proportional to the vibration amplitude when the vibration amplitude is not too large. In addition to the application in which the length of the metal strip is parallel to gravitation, the actuator also can be used with its length perpendicular to gravitation. However, the latter has a weaker capability of collecting small particles. It is also found that the actuator has a stronger capability to collect particles in water than in air.

Journal Article↗

PubMed2005

NGX6 gene inhibits cell proliferation and plays a negative role in EGFR pathway in nasopharyngeal carcinoma cells.

Nasopharyngeal carcinoma (NPC) is a common cancer in South China but is rare in other parts of the world. A novel NPC-related gene was isolated by location candidate cloning strategy, whose expression was down-regulated in NPC. This gene was designated human NGX6 (Genbank accession AF188239) and encoded a predicted protein of 338 amino acids that harbors an EGF-like domain. The effects of NGX6 on cells from human NPC cell line HNE1 were investigated. The cells transfected with NGX6 had a markedly high expression of NGX6, leading to significant decrease in cell proliferation and the capability to form colonies in soft agar, delaying the G0-G1 cell cycle progression. Flow cytometry assay indicated that the expression of cyclin D1 significantly decreased in NGX6-transfected HNE1 cells as well as cyclin A and E. There was a delay in tumor formation and a dramatic reduction in tumor size when cells transfected with NGX6 were injected into nude mice. In another way, we found NGX6 played a negative role in EGFR Ras/Mek/MAPK pathway. We propose that NGX6, as an EGF-like domain gene, could delay cell cycle G0-G1 progression and thus inhibit cell proliferation by negatively regulating EGFR pathway in NPC cells and down-regulating the expression of cyclin D1 and E.

Animals↗

PubMed2004

Role of a novel EGF-like domain-containing gene NGX6 in cell adhesion modulation in nasopharyngeal carcinoma cells.

The epidermal growth factor (EGF)-like domain is involved in receptor-ligand interactions, extracellular matrix formation, cell adhesion and chemotaxis. Nasopharyngeal carcinoma associated gene 6 (NGX6) is a novel EGF-like domain-containing gene located at the high frequent loss of heterozygosity (LOH) region 9p21-22 associated with nasopharyngeal carcinoma (NPC). It is down-regulated in NPC and its over-expression can delay the cell cycle G(0)-G(1) progression in NPC cells. In the present study, in situ hybridization analysis, using NPC tissue microarrays, showed that loss of NGX6 expression was associated with NPC lymph node metastasis. The Tet-on gene expression system and cDNA array techniques were used to profile the potential targets of NGX6. We found that NGX6 can influence the expression of some cell adhesion molecules in NPC cells. NGX6 can associate with ezrin, a linkage between the cell membrane and cytoskeleton. The NGX6 protein was expressed on the cell surface as a glycoprotein. Ectopic induction of NGX6 can impair NPC cell migration and invasive ability as well as improve cell adhesion and gap junctional intercellular communication, and can suppress tumor formation in vivo. The data revealed that NGX6 plays a role in cell adhesion modulation in NPC cells.

Animals↗

PubMed2004

Melanoma chondroitin sulfate proteoglycan enhances FAK and ERK activation by distinct mechanisms.

Melanoma chondroitin sulfate proteoglycan (MCSP) is an early cell surface melanoma progression marker implicated in stimulating tumor cell proliferation, migration, and invasion. Focal adhesion kinase (FAK) plays a pivotal role in integrating growth factor and adhesion-related signaling pathways, facilitating cell spreading and migration. Extracellular signal-regulated kinase (ERK) 1 and 2, implicated in tumor growth and survival, has also been linked to clinical melanoma progression. We have cloned the MCSP core protein and expressed it in the MCSP-negative melanoma cell line WM1552C. Expression of MCSP enhances integrin-mediated cell spreading, FAK phosphorylation, and activation of ERK1/2. MCSP transfectants exhibit extensive MCSP-rich microspikes on adherent cells, where it also colocalizes with alpha4 integrin. Enhanced activation of FAK and ERK1/2 by MCSP appears to involve independent mechanisms because inhibition of FAK activation had no effect on ERK1/2 phosphorylation. These results indicate that MCSP may facilitate primary melanoma progression by enhancing the activation of key signaling pathways important for tumor invasion and growth.

Amino Acid Sequence↗

PubMed2002

Selective activation of small GTPase RhoA by tyrosine kinase Etk through its pleckstrin homology domain.

Etk/Bmx is a member of the Btk family tyrosine kinase, which contains an N-terminal pleckstrin homology domain. Etk has been shown to play a pivotal role in the regulation of various cellular processes including differentiation, apoptosis, and cell motility. Here we present evidence that Etk is a modulator of the small GTPase RhoA. Etk and RhoA both are translocated to the plasma membrane and can form a complex upon serum stimulation in C2C12 cells. Etk interacts with RhoA but not other closely related small GTPases such as Cdc42 and Rac1, suggesting a specific modulation of RhoA by Etk. Our results demonstrate that Etk activates RhoA and enhances Rho-mediated stress fiber formation and transcription activity in a pleckstrin homology domain-dependent manner. Furthermore, Etk disrupts the interaction between RhoA and Rho-GDI (guanine nucleotide dissociation inhibitor) and promotes the membrane translocation of RhoA. Our data suggest that Etk plays an important role in regulation of RhoA-mediated signaling.

Animals↗

PubMed2002

Interaction between tyrosine kinase Etk and a RUN domain- and FYVE domain-containing protein RUFY1. A possible role of ETK in regulation of vesicle trafficking.

Etk/BMX tyrosine kinase is involved in regulation of various cellular processes including proliferation, differentiation, motility, and apoptosis. Through a yeast two-hybrid screening for the effectors of Etk, a new gene family designated as RUFY was identified. The RUFY gene family (RUFY1 and RUFY2) contains an N-terminal RUN domain and a C-terminal FYVE domain with two coiled-coil domains in-between. They appear to be homologues of a recently identified mouse Rabip4 (Cormant, M., Mari, M., Galmiche, A., Hofman, P., and Le Marchand-Brustel, Y. (2001) Proc. Natl. Acad. Sci. U. S. A. 98, 1637-1642). RUFY proteins are localized predominantly to endosomes as evidenced by their co-localization with early endosome antigen marker (EEA1). Etk interacts with RUFY1 through its SH3 and SH2 domains. RUFY1 is tyrosine-phosphorylated and appears to be a substrate of Etk. The RUFY1 mutant lacking the phosphorylation sites failed to go to the endosomes. Furthermore, overexpression of Etk in COS-1 and B82L cells resulted in increased plasma membrane localization of the epidermal growth factor receptor and delayed its induced endocytosis in COS-1 cells. The effects of Etk were blocked by the FYVE domain of RUFY1. Interestingly, the FYVE domain of RUFY1 is targeted to the plasma membrane through an interaction between its proline-rich motif and the SH3 domain of Etk or possibly some other membrane-associated SH3 domain-containing protein(s), whereas the lipid binding activity of the FYVE domain is not required. Our data suggest that Etk may be involved in regulation of endocytosis through its interaction with an endosomal protein RUFY1.

Adaptor Proteins, Signal Transducing↗

PubMed2002

[Benign symmetric lipomatosis].

OBJECTIVE: To explore the clinical feature of benign symmetric lipomatosis (BSL) so as to improve its diagnosis and treatment. METHOD: 28 patients of BSL treated in our hospital were analyzed and literature was reviewed. Surgical management is used in all patients. RESULT: There were no patients died. All patients were satisfactory with their appearance and function improved. 28 patients were followed up for 2-15 years (average 6 years and 5 months), only 5 cases recurred. CONCLUSION: BSL usually occurs in middle age men. Patients have a striking appearance "hump back" because of a diffuse, symmetric distribution of the lipomatous tissue in the cervical region. The etiology is related to alcohol abuse. Operation is the most effective treatment. The radical surgical therapy should not be emphasized because the important anatomic structures may be damaged. Abstaining from alcohol may help to reduce the rate of recurrence.

Adult↗

PubMed2001

Wave propagation in distributed media.

The problem of chemical reaction-diffusion wave propagation through a random, heterogeneous medium is considered using a model based on cubic autocatalysis with decay. The autocatalyst is taken to diffuse and react through a reactant loaded at constant initial concentration in a reaction domain except that there may be gaps of arbitrary width in which the reactant concentration is zero. We first study the propagation of a permanent-form wave across a single gap and determine the critical width of the gap in terms of the kinetic parameters in the system. The numerical results are compared with an analytical estimate. Next, the critical conditions for propagation across two gaps separated by a domain are determined numerically, and this is extended to a series of three gaps. From these results, a series of "rules" is established to allow us to predict whether a wave will pass through an arbitrary random array of gaps of a given size subject to some imposed total void fraction for the material. (c) 2001 American Institute of Physics.

Journal Article↗