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result(s) for
"Lu, A.T."
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Allowing for sex differences increases power in a GWAS of multiplex Autism families
2012
Current genomewide association studies account for only a small fraction of the estimated heritabilities of genetically complex neuropsychiatric disorders, indicating they are likely to result from the small effects of numerous predisposing variants, many of which have gone undetected. The statistical power to detect associations of common variants with small effects is increased by conducting joint association tests of a single nucleotide polymorphism (SNP), an additional risk factor (
F
), and their interaction.
F
can represent an environmental exposure, another genotype or any source of genetic heterogeneity. In case and control studies, logistic regression makes joint tests straightforward. This analytic method cannot be employed directly when SNP transmission tests are used to detect associations in parent/affected child trios and multiplex families. However, the method can be implemented using the case/pseudocontrol approach. We applied this approach to analyze data from a genomewide association study of multiplex families ascertained for Autism Spectrum Disorder, where sex was used to define the
F
. Joint analyses revealed two associations exceeding genomewide significance. One novel gene, Ryandine Receptor 2, implicated in calcium channel defects, was identified with a joint
P
-value of 3.9E−11. Calcium channel defects have been connected to Autism spectrum disorder (ASD) by Timothy Syndrome, which is Mendelian, and a previous targeted sex-specific association analysis of idiopathic Autism. A second gene, uridine phosphorylase 2, with a joint
P
-value of 2.3E−9, has been previously linked and associated with Autism in independent samples. These findings highlight two Autism candidate genes for follow-up studies.
Journal Article
QTL replication and targeted association highlight the nerve growth factor gene for nonverbal communication deficits in autism spectrum disorders
2013
Autism Spectrum Disorder (ASD) has a heterogeneous etiology that is genetically complex. It is defined by deficits in communication and social skills and the presence of restricted and repetitive behaviors. Genetic analyses of heritable quantitative traits that correlate with ASD may reduce heterogeneity. With this in mind, deficits in nonverbal communication (NVC) were quantified based on items from the Autism Diagnostic Interview Revised. Our previous analysis of 228 families from the Autism Genetics Research Exchange (AGRE) repository reported 5 potential quantitative trait loci (QTL). Here we report an NVC QTL replication study in an independent sample of 213 AGRE families. One QTL was replicated (
P
<0.0004). It was investigated using a targeted-association analysis of 476 haplotype blocks with 708 AGRE families using the Family Based Association Test (FBAT). Blocks in two QTL genes were associated with NVC with a
P
-value of 0.001. Three associated haplotype blocks were intronic to the Nerve Growth Factor (
NGF
) gene (
P
=0.001, 0.001, 0.002), and one was intronic to
KCND3
(
P
=0.001). Individual haplotypes within the associated blocks drove the associations (0.003, 0.0004 and 0.0002) for
NGF
and 0.0001 for
KCND3
. Using the same methods, these genes were tested for association with NVC in an independent sample of 1517 families from an Autism Genome Project (AGP). NVC was associated with a haplotype in an adjacent
NGF
block (
P
=0.0005) and one 46 kb away from the associated block in
KCND3
(0.008). These analyses illustrate the value of QTL and targeted association studies for genetically complex disorders such as ASD.
NGF
is a promising risk gene for NVC deficits.
Journal Article
Cell surface expression of single chain antibodies with applications to imaging of gene expression in vivo
by
Osen, Maureen
,
Li, King C.
,
Northrop, Jeffrey P.
in
Animals
,
Antibodies - immunology
,
Cell Membrane - metabolism
2003
Imaging of gene expression in vivo has many potential uses for biomedical research and drug discovery, ranging from the study of gene regulation and cancer to the non-invasive assessment of gene therapies. To streamline the development of imaging marker gene technologies for nuclear medicine, we propose a new approach to the design of reporter/probe pairs wherein the reporter is a cell surface-expressed single chain antibody variable fragment that has been raised against a low molecular weight imaging probe with optimized pharmacokinetic properties. Proof of concept of the approach was achieved using a single chain antibody variable fragment that binds with high affinity to fluorescein and an imaging probe consisting of fluorescein isothiocyanate coupled to the chelator diethylene triamine penta-acetic acid labeled with the gamma-emitter (111)In. We demonstrate specific high-affinity binding of this probe to the cell surface-expressed reporter in vitro and assess the in vivo biodistribution of the probe both in wild-type mice and in mice harboring tumor xenografts expressing the reporter. Specific uptake of the probe by, and in vivo imaging of, tumors expressing the reporter are shown. Since ScFvs with high affinities can be raised to almost any protein or small molecule, the proposed methodology may offer a new flexibility in the design of imaging tracer/reporter pairs wherein both probe pharmacokinetics and binding affinities can be readily optimized.
Journal Article
DNA Methylation Networks Underlying Mammalian Traits
2021
Summary Epigenetics has hitherto been studied and understood largely at the level of individual organisms. Here, we report a multi-faceted investigation of DNA methylation across 11,117 samples from 176 different species. We performed an unbiased clustering of individual cytosines into 55 modules and identified 31 modules related to primary traits including age, species lifespan, sex, adult species weight, tissue type and phylogenetic order. Analysis of the correlation between DNA methylation and species allowed us to construct phyloepigenetic trees for different tissues that parallel the phylogenetic tree. In addition, while some stable cytosines reflect phylogenetic signatures, others relate to age and lifespan, and in many cases responding to anti-aging interventions in mice such as caloric restriction and ablation of growth hormone receptors. Insights uncovered by this investigation have important implications for our understanding of the role of epigenetics in mammalian evolution, aging and lifespan. Competing Interest Statement SH is a founder of the non-profit Epigenetic Clock Development Foundation which plans to license several patents from his employer UC Regents. These patents list SH and JE as inventors. The other authors declare no conflicts of interest.
Epigenetic predictors of maximum lifespan and other life history traits in mammals
2021
Maximum lifespan of a species is the oldest that individuals can survive, reflecting the genetic limit of longevity in an ideal environment. Here we report methylation-based models that accurately predict maximum lifespan (r=0.89), gestational time (r=0.96), and age at sexual maturity (r=0.87), using cytosine methylation patterns collected from over 12,000 samples derived from 192 mammalian species. Our epigenetic maximum lifespan predictor corroborated the extended lifespan in growth hormone receptor knockout mice and rapamycin treated mice. Across dog breeds, epigenetic maximum lifespan correlates positively with breed lifespan but negatively with breed size. Lifespan-related cytosines are located in transcriptional regulatory regions, such as bivalent chromatin promoters and polycomb-repressed regions, which were hypomethylated in long-lived species. The epigenetic estimators of maximum lifespan and other life history traits will be useful for characterizing understudied species and for identifying interventions that extend lifespan.
Pressure-induced emission of cesium lead halide perovskite nanocrystals
2018
Metal halide perovskites (MHPs) are of great interest for optoelectronics because of their high quantum efficiency in solar cells and light-emitting devices. However, exploring an effective strategy to further improve their optical activities remains a considerable challenge. Here, we report that nanocrystals (NCs) of the initially nonfluorescent zero-dimensional (0D) cesium lead halide perovskite Cs
4
PbBr
6
exhibit a distinct emission under a high pressure of 3.01 GPa. Subsequently, the emission intensity of Cs
4
PbBr
6
NCs experiences a significant increase upon further compression. Joint experimental and theoretical analyses indicate that such pressure-induced emission (PIE) may be ascribed to the enhanced optical activity and the increased binding energy of self-trapped excitons upon compression. This phenomenon is a result of the large distortion of [PbBr
6
]
4−
octahedral motifs resulting from a structural phase transition. Our findings demonstrate that high pressure can be a robust tool to boost the photoluminescence efficiency and provide insights into the relationship between the structure and optical properties of 0D MHPs under extreme conditions.
The potential optoelectronic applications of metal halide perovskites make exploration and tuning of their optical properties of great interest. Here the authors show that non-emitting zero-dimensional cesium lead halide perovskites become strongly fluorescent under high pressure, due to distortion-induced effects.
Journal Article
Endoplasmic reticulum ribosome-binding protein 1 (RRBP1) overexpression is frequently found in lung cancer patients and alleviates intracellular stress-induced apoptosis through the enhancement of GRP78
2013
Lung cancer is the leading cause of cancer deaths and is the most occurring malignancy worldwide. Unraveling the molecular mechanisms involved in lung tumorigenesis will greatly improve therapy. During early tumorigenesis, rapid proliferating tumor cells require increased activity of endoplasmic reticulum (ER) for protein synthesis, folding and secretion, thereby are subjected to ER stress. Ribosome-binding protein 1 (RRBP1) was originally identified as a ribosome-binding protein located on the rough ER and associated with unfolding protein response (UPR). In this report, we investigated the role of RRBP1 in lung cancer. RRBP1 was highly expressed in lung cancer tissue, as compared with adjacent normal tissues as assessed by immunohistochemistry (IHC) using lung cancer tissue array (
n=
87). Knockdown of RRBP1 by short-hairpin RNAs caused ER stress and significantly reduced cell viability and tumorigenicity. This effect was associated with a significant reduction in the expression of glucose-regulated protein 78 (GRP78). UPR regulator GRP78, an anti-apoptotic protein that is widely upregulated in cancer, has a critical role in chemotherapy resistance in some cancers. According to our results, cells with a higher level of RRBP1 were more resistant to ER stress. Ectopic expression of RRBP1 alleviated apoptosis that was induced by the ER-stress agent tunicamycin, 2-deoxy-
D
-glucose (2DG) or doxorubicin via enhancing GRP78 protein expression. A strong correlation was observed between the expression of RRBP1 and GRP78 in tumor biopsies using the database GSE10072. Our results also indicated that RRBP1 may involve in the regulation of mRNA stability of UPR components including ATF6 and GRP78. Taken together, RRBP1 could alleviate ER stress and help cancer cell survive. RRBP1 is critical for tumor cell survival, which may make it a useful target in lung cancer treatment and a candidate for the development of new targeted therapeutics.
Journal Article
Electrical Wind Force-Driven and Dislocation-Templated Amorphization in Phase-Change Nanowires
by
Li, Ju
,
Jung, Yeonwoong
,
Johnson, A.T. Charlie
in
computer hardware
,
Computer Storage Devices
,
Condensed matter: structure, mechanical and thermal properties
2012
Phase-change materials undergo rapid and reversible crystalline-to-amorphous structural transformation and are being used for nonvolatile memory devices. However, the transformation mechanism remains poorly understood. We have studied the effect of electrical pulses on the crystalline-to-amorphous phase change in a single-crystalline Ge₂Sb₂Te₂ (GST) nanowire memory device by in situ transmission electron microscopy. We show that electrical pulses produce dislocations in crystalline GST, which become mobile and glide in the direction of hole-carrier motion. The continuous increase in the density of dislocations moving unidirectionally in the material leads to dislocation jamming, which eventually induces the crystalline-to-amorphous phase change with a sharp interface spanning the entire nanowire cross section. The dislocation-templated amorphization explains the large on/off resistance ratio of the device.
Journal Article
14-3-3σ Regulates Keratinocyte Proliferation and Differentiation by Modulating Yap1 Cellular Localization
by
Xue, Lei
,
Dean, Douglas C.
,
Lu, Qingxian
in
14-3-3 Proteins - metabolism
,
9,10-Dimethyl-1,2-benzanthracene
,
Active Transport, Cell Nucleus
2015
The homozygous repeated epilation (Er/Er) mouse mutant of the gene encoding 14-3-3σ displays an epidermal phenotype characterized by hyperproliferative keratinocytes and undifferentiated epidermis. Heterozygous Er/+ mice develop spontaneous skin tumors and are highly sensitive to tumor-promoting 7,12-dimethylbenzanthracene/12-O-tetradecanoyl-phorbol-13-acetate induction. The molecular mechanisms underlying 14-3-3σ regulation of epidermal proliferation, differentiation, and tumor formation have not been well elucidated. In this study, we found that Er/Er keratinocytes failed to sequester Yap1 in the cytoplasm, leading to its nuclear localization during epidermal development in vivo and under differentiation-inducing culture conditions in vitro. In addition, enhanced Yap1 nuclear localization was also evident in 7,12-dimethylbenzanthracene/12-O-tetradecanoyl-phorbol-13-acetate–induced tumors from Er/+ skin. Furthermore, short hairpin RNA (shRNA) knockdown of Yap1 expression in Er/Er keratinocytes inhibited their proliferation, suggesting that YAP1 functions as a downstream effector of 14-3-3σ controlling epidermal proliferation. We then demonstrated that keratinocytes express all seven 14-3-3 protein isoforms, some of which form heterodimers with 14-3-3σ, either full-length wild type (WT) or the mutant form found in Er/Er mice. However, Er 14-3-3σ does not interact with Yap1, as demonstrated by coimmunoprecipitation. We conclude that Er 14-3-3σ disrupts the interaction between 14-3-3 and Yap1, and thus fails to block Yap1 nuclear transcriptional function, causing continued progenitor expansion and inhibition of differentiation in the Er/Er epidermis.
Journal Article
The Rise of People-Centric Sensing
2008
Technological advances in sensing, computation, storage, and communications will turn the near-ubiquitous mobile phone into a global mobile sensing device. People-centric sensing will help drive this trend by enabling a different way to sense, learn, visualize, and share information about ourselves, friends, communities, the way we live, and the world we live in. It juxtaposes the traditional view of mesh sensor networks with one in which people, carrying mobile devices, enable opportunistic sensing coverage. In the MetroSense Project's vision of people-centric sensing, users are the key architectural system component, enabling a host of new application areas such as personal, public, and social sensing.
Journal Article