Biomedical subjects

Yingli Wang

Publications and source records attributed to Yingli Wang.

10 recordsLinked to original sources

PubMed2006

Identification of a novel human lysophosphatidic acid acyltransferase, LPAAT-theta, which activates mTOR pathway.

Lysophosphatidic acid acyltransferase (LPAAT) is an intrinsic membrane protein that catalyzes the synthesis of phosphatidic acid (PA) from lysophosphatidic acid (LPA). It is well known that LPAAT is involved in lipid biosynthesis, while its role in tumour progression has been of emerging interest in the last few years. To date, seven members of the LPAAT gene family have been found in human. Here we report a novel LPAAT member, designated as LPAAT-theta, which was 2728 base pairs in length and contained an open reading frame (ORF) encoding 434 amino acids. The LPAAT-theta gene consisted of 12 exons and 11 introns, and mapped to chromosome 4q21.23. LPAAT-theta was ubiquitously expressed in 18 human tissues by RT-PCR analysis. Subcellular localization of LPAAT-theta-EGFP fusion protein revealed that LPAAT-theta was distributed primarily in the endoplasmic reticulum (ER) of COS-7 cells. Furthermore, we found that the overexpression of LPAAT-theta can induce mTOR-dependent p70S6K phosphorylation on Thr389 and 4EBP1 phosphorylation on Ser65 in HEK293T cells.

Acyltransferases↗

PubMed2006

BRSK2 is activated by cyclic AMP-dependent protein kinase A through phosphorylation at Thr260.

Brain selective kinase 2 (BRSK2) has been identified as a member of AMPK related kinases. LKB1 can phosphorylate the Thr174 of BRSK2, increasing its activity >50-fold. In this study, we identified cAMP-dependent protein kinase A (PKA) as another upstream kinase of BRSK2, which can phosphorylate BRSK2 at Thr260. The association between these two proteins was confirmed by GST pull-down. Furthermore, our study indicated that the kinase activity of BRSK2 can be increased through phosphorylation by PKA.

Amino Acid Sequence↗

PubMed2006

Transcriptional inhibition by an oxidized abasic site in DNA.

2-Deoxyribonolactone (dL) is an oxidized abasic site in DNA that can be induced by gamma-radiolysis, ultraviolet irradiation, and numerous antitumor drugs. Although this lesion is incised by AP endonucleases, suggesting a base-excision repair mechanism for dL removal, subsequent excision and repair synthesis by DNA polymerase beta is inhibited due to accumulation of a protein-DNA cross-link. This raises the possibility that additional repair pathways might be required to eliminate dL from the genome. Transcription-coupled repair (TCR) is a pathway of excision repair specific to DNA lesions present in transcribed strands of expressed genes. A current model proposes that transcription arrest at the site of DNA damage is required to initiate TCR. In support of this model, a strong correlation between transcription arrest by a lesion in vitro and TCR of the lesion in vivo has been found in most cases analyzed. To assess whether dL might be subject to TCR, we have studied the behavior of bacteriophage T3 and T7 RNA polymerases (T3RNAP, T7RNAP) and of mammalian RNA polymerase II (RNAPII) when they encounter a dL lesion or its "caged" precursor located either in the transcribed or in the nontranscribed strand of template DNA. DNA plasmids containing a specifically located dL downstream of the T3, T7 promoter or the Adenovirus major late promoter were constructed and used for in vitro transcription with purified proteins. We found that both dL and its caged precursor located in the transcribed strand represented a complete block to transcription by T3- and T7RNAP. Similarly, they caused more than 90% arrest when transcription was carried out with mammalian RNAPII. Furthermore, RNAPII complexes arrested at dL were subject to the transcript cleavage reaction mediated by elongation factor TFIIS, indicating that these complexes were stable. A dL in the nontranscribed strand did not block either polymerase.

Animals↗

PubMed2006

Optical image processing using the photoinduced anisotropy of pyrrylfulgide.

A synthesized photochromic compound-pyrrylfulgide--is prepared as a thin film doped in a polymethylmethacrylate (PMMA) matrix. Under irradiation by UV light, the film converts from the bleached state into a colored state that has a maximum absorption at 635 nm and is thermally stable at room temperature. When the colored state is irradiated by a linearly polarized 650 nm laser, the film returns to the bleached state; photoinduced anisotropy is produced during this process. Application of optical image processing methods using the photoinduced anisotropy of the pyrrylfulgide/PMMA film is described. Examples in non-Fourier optical image processing, such as contrast reversal and image subtraction and summation, as well as in Fourier optical image processing, such as low-pass filtering and edge enhancement, are presented.

Anisotropy↗

PubMed2005

Polarization holographic high-density optical data storage in bacteriorhodopsin film.

Optical films containing the genetic variant bacteriorhodopsin BR-D96N were experimentally studied in view of their properties as media for holographic storage. Different polarization recording schemes were tested and compared. The influence of the polarization states of the recording and readout waves on the retrieved diffractive image's intensity and its signal-to-noise ratio were analyzed. The experimental results showed that, compared with the other tested polarization relations during holographic recording, the discrimination between the polarization states of diffracted and scattered light is optimized with orthogonal circular polarization of the recording beams, and thus a high signal-to-noise ratio and a high diffraction efficiency are obtained. Using a He-Ne laser (633 nm, 3 mW) for recording and readout, a spatial light modulator as a data input element, and a 2D-CCD sensor for data capture in a Fourier transform holographic setup, a storage density of 2 x 10(8) bits/cm2 was obtained on a 60 x 42 microm2 area in the BR-D96N film. The readout of encoded binary data was possible with a zero-error rate at the tested storage density.

Journal Article↗

PubMed2005

Polarization multiplexed write-once-read-many optical data storage in bacteriorhodopsin films.

In polymeric films of bacteriorhodopsin (BR) a photoconversion product, which was named the F620 state, was observed on excitation of the film with 532 nm nanosecond laser pulses. This photoproduct shows a strong nonlinear absorption. Such BR films can be used for write-once-read-many (WORM) optical data storage. We demonstrate that a photoproduct similar or even identical to that obtained with nanosecond pulses is generated on excitation with 532 nm femtosecond pulses. This photoproduct also shows strong anisotropic absorption, which facilitates polarization storage of data. The product is thermally stable and is irretrievable to the initial B state either by photochemical reaction or through a thermal pathway. The experimental results indicate that the product is formed by a two-photon absorption process. Optical WORM storage is demonstrated by use of two polarization states, but more polarization states may be used. The combination of polarization data multiplexing and extremely short recording time in the femtosecond range enables very high data volumes to be stored within a very short time.

Journal Article↗

PubMed2005

Abnormalities in cartilage and bone development in the Apert syndrome FGFR2(+/S252W) mouse.

Apert syndrome is an autosomal dominant disorder characterized by malformations of the skull, limbs and viscera. Two-thirds of affected individuals have a S252W mutation in fibroblast growth factor receptor 2 (FGFR2). To study the pathogenesis of this condition, we generated a knock-in mouse model with this mutation. The Fgfr2(+/S252W) mutant mice have abnormalities of the skeleton, as well as of other organs including the brain, thymus, lungs, heart and intestines. In the mutant neurocranium, we found a midline sutural defect and craniosynostosis with abnormal osteoblastic proliferation and differentiation. We noted ectopic cartilage at the midline sagittal suture, and cartilage abnormalities in the basicranium, nasal turbinates and trachea. In addition, from the mutant long bones, in vitro cell cultures grown in osteogenic medium revealed chondrocytes, which were absent in the controls. Our results suggest that altered cartilage and bone development play a significant role in the pathogenesis of the Apert syndrome phenotype.

Acrocephalosyndactylia↗

PubMed2003

Characteristics and mechanisms of the two types of photoelectric differential response of bacteriorhodopsin-based photocell.

Bacteriorhodopsin (BR)-based photocells have been assigned possessing differential photoelectric response. But recently we found that the differential response described before, which occurred in milliseconds to seconds, outputting a positive pulse when light was on and a negative pulse when light was off, was not the intrinsic property of the BR molecule. It was partially caused by the measuring circuit. By measuring the photoelectric response signal of the BR film photocell to a short laser pulse, the impulse response function of the BR film photocell was obtained by data fitting with MATLAB software. A simulation system was accordingly developed. The output response signals of the BR film photocell under different stepping incident light were calculated. By simulation and analysis, it was concluded that the differential response caused by the intrinsic property of the BR molecule happened in microseconds time scale, and it produced a negative pulse when light was on and a positive pulse when light was off. It was much faster but much weaker than that described before.

Bacteriorhodopsins↗

PubMed2002

Mechanisms of pulse response and differential response of bacteriorhodopsin and their relations.

Bacteriorhodopsin (BR) films are oriented and deposited on indium tin oxide conductive glass by using electrophoretic sedimentation and Langmuir-Blodgett methods to construct sandwich-type photocells, respectively. The pulse response photoelectric signal of the BR photocell under pulsed laser and the differential response photoelectric signal under irradiation of interval light are measured. The origins of these two types of photoelectric responses and their correlations are analyzed. The pulse response signal initiates from the ultrafast charge separation of the retinal and the proton translocation followed by the deprotonation and reprotonation of the Schiff base and its surrounding amino acids. This is a quick response and is the preceding reaction of the differential response. The differential response signal is caused by the charging and discharging of the continuous proton current of the BR light-driven proton pump at light-on and light-off, which is a slow process. The differential response is related to not only the construction of the BR photocell but also the coupling mode of measurement. To observe the differential response signal, the BR photocell must have large enough B3 and B3' components in its pulse response as well as an alternative coupling mode to measure it.

Bacteriorhodopsins↗

PubMedDate not supplied

Chemoenzymatic synthesis and antibody detection of DNA glycoconjugates.

A chemoenzymatic approach for the efficient synthesis of DNA-carbohydrate conjugates was developed and applied to an antibody-based strategy for the detection of DNA glycoconjugates. A phosphoramidite derivative of N-acetylglucosamine (GlcNAc) was synthesized and utilized to attach GlcNAc sugars to the 5'-terminus of DNA oligonucleotides by solid-phase DNA synthesis. The resulting GlcNAc-DNA conjugates were used as substrates for glycosyl transferase enzymes to synthesize DNA glycoconjugates. Treatment of GlcNAc-DNA with beta-1,4-galactosyl transferase (GalT) and UDP-Gal produced N-acetyllactosamine-modified DNA (LacNAc-DNA), which could be converted quantitatively to the trisaccharide Lewis X (LeX)-DNA conjugate by alpha-1,3-fucosyltransferase VI (FucT) and GDP-Fuc. The facile enzymatic synthesis of LeX-DNA from GlcNAc-DNA also was accomplished in a one-pot reaction by the combined action of GalT and FucT. The resulting glycoconjugates were characterized by gel electrophoresis, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), and glycosidase digestion experiments. Covalent modification of the 5'-terminus of DNA with carbohydrates did not interfere with the ability of DNA glycoconjugates to hybridize with complementary DNA, as indicated by UV thermal denaturation analysis. The trisaccharide DNA glycoconjugate, LeX-DNA, was detected by a dual DNA hybridization/monoclonal antibody (mAb) detection protocol ("Southwestern"): membrane-immobilized LeX-DNA was visualized by Southern detection with a radiolabeled complementary DNA probe and by Western chemiluminescence detection with a mAb specific for the LeX antigen. The efficient chemoenzymatic synthesis of DNA glycoconjugates and the Southwestern detection protocol may facilitate the application of glycosylated DNA to cellular targeting and DNA glycoconjugate detection strategies.

Acetylglucosamine↗