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At least 721 records · Page 40

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DOE OSTI2017

The forkhead-like transcription factor (Fhl1p) maintains yeast replicative lifespan by regulating ribonucleotide reductase 1 (RNR1) gene transcription

In eukaryotes, numerous genetic factors contribute to the lifespan including metabolic enzymes, signal transducers, and transcription factors. As previously reported, the forkhead-like transcription factor (FHL1) gene was required for yeast replicative lifespan and cell proliferation. To determine how Fhl1p regulates the lifespan, we performed a DNA microarray analysis of a heterozygous diploid strain deleted for FHL1. We discovered numerous Fhl1p-target genes, which were then screened for lifespan-regulating activity. We identified the ribonucleotide reductase (RNR) 1 gene (RNR1) as a regulator of replicative lifespan. RNR1 encodes a large subunit of the RNR complex, which consists of two large (Rnr1p/Rnr3p) and two small (Rnr2p/Rnr4p) subunits. Heterozygous deletion of FHL1 reduced transcription of RNR1 and RNR3, but not RNR2 and RNR4. Chromatin immunoprecipitation showed that Fhl1p binds to the promoter regions of RNR1 and RNR3. Cells harboring an RNR1 deletion or an rnr1-C428A mutation, which abolishes RNR catalytic activity, exhibited a short lifespan. In contrast, cells with a deletion of the other RNR genes had a normal lifespan. Overexpression of RNR1, but not RNR3, restored the lifespan of the heterozygous FHL1 mutant to the wild-type (WT) level. The Δfhl1/FHL1 mutant conferred a decrease in dNTP levels and an increase in hydroxyurea (HU) sensitivity. These findings reveal that Fhl1p regulates RNR1 gene transcription to maintain dNTP levels, thus modulating longevity by protection against replication stress. - Highlights: • Fhl1p regulates replicative lifespan and transcription of RNR large subunit genes. • Rnr1p uniquely acts as a lifespan regulator independent of the RNR complex. • dNTP levels modulate longevity by protection against replication stress.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2017

miR-141-3p functions as a tumor suppressor modulating activating transcription factor 5 in glioma

Glioma is the most common malignant primary brain tumor which arises from the central nervous system. Our studies reported that an anti-apoptotic factor, activating transcription factor 5 (ATF5), is highly expressed in malignant glioma specimens and cell lines. Downregulation by dominant-negetive ATF5 could repress glioma cell proliferation and accelerate apoptosis. Here, we further investigate the upstream factor which regulates ATF5 expression. Bioinformatic analysis showed that ATF5 was a potential target of miR-141-3p. Luciferase reporter assay verified that miR-141-3p specifically targeted the ATF5 3′-UTR in glioma cells. Functional studied suggested that miR-141-3p overexpression inhibited proliferation and promoted apoptosis of glioma cells (U87MG and U251). Xenograft experiments proved the inhibition of miR-141-3p on glioma growth in vivo. Moreover, exogenous ATF5 without 3′-UTR restored the cell proliferation inhibition triggered by miR-141-3p. Taken together, we put forward that miR-141-3p is a new upstream target towards ATF5. It can serve as a crucial tumor suppressor in regulating the ATF5-regulated growth of malignant glioma. - Highlights: • ATF5 was highly expressed in gliomas and was essential for cell proliferation and apoptosis. • MiR-141-3p specifically targeted the ATF5 3′-UTR in glioma cells. • MiR-141-3p was significantly downregulated in glioma tissues and cell lines. • MiR-141-3p inhibited glioma growth through repressing ATF5 expression in vitro and in vivo. • Exogenous expression of ATF5 rescued cells from proliferation inhibition triggered by miR-141-3p.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2018

An AT-hook protein DEPRESSED PALEA1 physically interacts with the TCP Family transcription factor RETARDED PALEA1 in rice

Highlights: • The AT-hook protein DP1 physically interacts with the TCP family transcription factor REP1 in rice. • In maize, the AT-hook protein BAD1 physically interacts with the TCP family transcription factor BAF1. • The interaction between AT-hook proteins and TCP proteins may be conserved in rice and maize. The cereal crops (such as rice and maize) which belong to the grass family, are the most important grain crops for human beings, and the development of their flower and inflorescence architecture has attracted extensive attention. Although multiple genes involved in the regulation of floral and inflorescence organogenesis have been identified, the underlying molecular mechanisms are largely unknown. Previously, we identified rice depressed palea1 (dp1) mutants with defects in main structure of palea and its enhancer RETARDED PALEA1 (REP1). DP1 is an AT-hook protein while REP1 is a TCP transcription factor, both of which are important regulators of palea development. However, the relationship of these two proteins has not been elucidated yet. Here, we demonstrated that DP1 interacts physically with REP1 both in yeast and in rice protoplasts. Considering the close phylogenetic relationship between maize and rice, we further hypothesize that their orthologs in maize, BARREN STALK FASTIGIATE (BAF1) and BRANCH ANGLE DEFECTIVE 1 (BAD1), may interact physically. Subsequently, we verified their physical interaction, indicating that the interaction between AT-hook proteins and TCP proteins is conserved in rice and maize. Our findings may reveal a novel molecular mechanism of floral and inflorescence development in grasses.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2018

Kruppel-like factor 4 (KLF-4) plays a crucial role in simvastatin (SVT)-induced differentiation of rabbit articular chondrocytes

Highlights: • SVT was shown to exhibit a protective effect on chondrocytes. • KLF-4 regulates the SVT-mediated differentiation of chondrocytes. • KLF-4 plays critical role in SVT-mediated chondrocyte differentiation. Simvastatin is a cholesterol-lowing reagent that is derived synthetically from the fermentation of Aspergillus terreus. Recently, SVT has been shown to possess a protective effect of chondrocytes. Kruppel-like factor 4 (KLF-4) is a zinc finger transcription factor that plays crucial roles during the development and maintenance of multiple organs. However, the roles of KLF-4 in chondrocytes have not been well unknown. Here, we investigated whether KLF-4 regulates SVT-caused differentiated phenotype of chondrocytes. A KLF-4 cDNA or KLF-4 siRNA was transfected into SVT-treated chondrocytes. Western blot analysis, RT-PCR and immunofluorescence staining analyzed expression of type II collagen and SOX-9, marker proteins of differentiation. The results showed overexpression of KLF-4 accelerates SVT-induced type II collagen expression, as determined by western blot analysis and causes sulfated-proteoglycan synthesis, as detected by Alcian blue staining. RT-PCR revealed that ectopic expression of KLF-4 induces SVT-caused SOX-9, a transcription factor of type II collagen, expression. Transfection of KLF-4 siRNA reversed SVT-caused type II collagen and SOX-9 expression and inhibited SVT-induced sulfated proteoglycan production. This study indicates that KLF-4 plays critical role in SVT-caused chondrocytes differentiation.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2018

Fibroblast growth factor 19 protects the heart from oxidative stress-induced diabetic cardiomyopathy via activation of AMPK/Nrf2/HO-1 pathway

Highlights: • FGF19 Improves Cardiac Dysfunction and Fibrosis in Diabetic Cardiomyopathy. • FGF19 Prevent Cardiac Oxidative Stress in the Diabetic Heart. • FGF 19 induces expression Nrf2/HO-1 signaling axis through activation of AMPK. Diabetes affects cardiac structure and function, where it leads to diabetic cardiomyopathy. Reactive oxygen species (ROS) produced by oxidative stress play an important role in the development of diabetic cardiomyopathy. Fibroblast growth factor (FGF) 19, an enterokine, is synthesized and released into the ileum. In the present study, we revealed that FGF19 induced an antioxidant response through stimulating the expression of nuclear erythroid factor 2 (NE-F2)-related factor 2 (Nrf2) and as well as reducing ROS production through the AMPK signaling pathway. Additionally, AMPK inhibition by the AMPK-specific inhibitor compound C decreased Nrf2 and heme oxygenase-1 (HO-1) protein expression. Taken together, these results suggested that FGF19, through the anti-oxidative defense system, attenuated the development of diabetic cardiomyopathy and restored cardiac function.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2018

The cytoskeletal protein Zyxin interacts with the zinc-finger transcription factor Zic1 and plays the role of a scaffold for Gli1 and Zic1 interactions during early development of Xenopus laevis

Highlights: • Zyxin can interact with the transcription factor Zic1. • Zyxin, Zic1 and Gli1 can form a triple complex in the nucleus. • Triple complex Gli1 + Zic + Zyxin enhances the activity of Gli1 + Zic complex. We have shown recently that the cytoskeletal protein Zyxin participates in the fine tuning of the neural plate pattering in Xenopus laevis embryos by modulating activity of one of the effectors of Hedgehog (Shh) signaling cascade, the transcription factor Gli1. In the present work, we show that Zyxin can also interact with the potential modulator of the Shh pathway, the transcription factor Zic1. The interaction of proteins occurs primarily by mean of the zinc-finger domain of Zic1 and 2nd LIM domain of Zyxin. Moreover, we have also revealed the ability of the Zyxin, Zic1 and Gli1 to form a ternary complex. The activity of this complex resembles that of the previously described by other authors protein complex formed by Gli1 and Zic1, amplifying effect of the latter. The data obtained provide evidence for the scaffolding role of Zyxin for Gli1 and Zic1 interactions and confirm its role in the regulation of Shh signaling cascade.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2018

p-Coumaric acid stimulates longitudinal bone growth through increasing the serum production and expression levels of insulin-like growth factor 1 in rats

The aim of the present study was to examine the effects of p-coumaric acid on the longitudinal growth of the long bone in adolescent male rats. Teatment with p-coumaric acid significantly increased the tibial length and the height of each growth plate zone and the ratio of 5-bromo-2′-deoxyuridine-positive cells relative to total proliferative cells. Expression of insulin-like growth factor 1 and its receptor in the proliferative and hypertrophic zones, and serum levels of growth hormone and insulin-like growth factor 1 were significantly increased as well in the p-coumaric acid-treated group. Via increasing both the serum level of insulin-like growth factor 1 and its expression, p-coumaric acid could promote cell proliferation in growth plate zones. These results suggest that p-coumaric acid has the potential to increase height and may be a feasible alternative to growth hormone therapy.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2018

Transforming growth factor alpha promotes tumorigenesis and regulates epithelial-mesenchymal transition modulation in colon cancer

Highlights: • TGFα facilitates short-term and long-term proliferations of colon cancer cells. • TGFα was suggested as a migration-and-invasion promoting factor of colon cancer. • TGFα modulates epithelial-mesenchymal transition markers and NFκB signaling pathway in colon cancer cells. Colon cancer is one of the most common cancers in the developed countries. The association between transforming growth factor TGFα and human cancer incidence has been suggested, yet, the regulatory roles of TGFα and the molecular mechanisms remain unknown, especially in colon cancer. We aim to investigate the functional regulations of TGFα in colon cancer progression. Two colon cancer cell lines were applied, and plasmid overexpression and siRNA-mediated depletion techniques were used to verify the role of TGFα in colon cancer. Cell proliferation was analyzed by MTS assay and colony formation assay, and western blot assay was used to examine protein expression. Migration, invasion, and reporter assays were also carried out to study the regulations of TGFα in colon cancer. Our results evidenced that expression of TGFα facilitates short-term and long-term proliferations of colon cancer cells. Moreover, TGFα was suggested as a migration-and-invasion promoting factor of colon cancer. Finally, our data indicated that TGFα modulates epithelial-mesenchymal transition (EMT) markers and NFκB signaling pathway in colon cancer cells. We provide the first time evidence of the promoting role TGFα plays in colon cancer tumorigenesis with proposed regulatory mechanisms involving EMT alteration and NFκB signaling pathway.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2018

Insulin-like growth factor binding Protein-3 suppresses osteoblast differentiation via bone morphogenetic protein-2

Highlights: • The maintenance of bone mass after induction of bone formation is difficult. • Insulin-like growth factor (IGF)-1 regulates bone mass including osteogenesis. • IGF-binding proteins (IGFBPs) are important for IGF-1 stability. • Bone morphogenetic protein-2 (BMP-2) induces osteoblast differentiation. • IGFBP-3 counteracts the effect of BMP-2 and suppresses bone formation. Bone augmentation therapy is used in dental implantation. While techniques to induce bone formation are generally successful, the maintenance of bone mass is more difficult. Therefore, it is important to understand the mechanisms that regulate this process. Insulin-like growth factor-1 (IGF-1) is one of the most abundant growth factors that regulate bone mass, promote osteoblast differentiation, and accelerate bone formation. The activity of IGF-1 is regulated by IGF-binding proteins (IGFBPs). IGFBP-3 forms a ternary complex with IGF-1, extending its half-life in the circulating system. Therefore, IGFBP-3 acts as a stabilizer and transporter of IGF-1. Recent studies reported new IGF-1-independent functions of IGFBP-3 related with bone metabolism. In this study, we investigated the function of IGFBP-3 in osteoblast differentiation. Our results showed that IGFBP-3 decreases the expression of osteoblast differentiation markers, whose expression is enhanced by bone morphogenetic protein-2 (BMP-2). IGFBP-3 also reduced BMP-2 effect on ALP activity and mineral nodule formation. In addition, IGFBP-3 suppresses the activity of the Smad Binding Element (SBE) reporter, induced by BMP-2 signaling. These results suggest that IGFBP-3 inhibits osteoblast differentiation through the BMP-2 signal pathway, and that IGFBP-3 might play a role in bone mass maintenance in an IGF-1-dependent and -independent manner.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2020

The impacts of building characteristics, social psychological and cultural factors on indoor environment quality productivity belief

Indoor environmental quality (IEQ) plays a key role in determining occupants' productivity at work; however, analyses of the interconnected factors among building physical, attitudinal, social and demographic components in one study are lacking. To fill this research gap, this study investigates these interconnected factors' influence on occupants’ IEQ-productivity belief, defined as a personal, subjective evaluation of the linkage between the impacts of five IEQ aspects (the quality of indoor temperature, air, natural and electric lighting, and acoustics) and productivity. A cross-sectional survey data was collected in university offices from six countries (Brazil, Italy, Poland, Switzerland, Taiwan and the U.S.). Results of multiple linear regression models indicate that IEQ satisfaction is the strongest positive predictor of the IEQ-productivity belief and this relationship is stronger in private offices. Country of residence is the second primary predictor. Several attitudinal-behavioral factors, including thermal comfort, perceived ease of controlling indoor environmental features, and attitudes toward sharing controls are all positively associated with IEQ-productivity belief. Interestingly, the level of control accessibility to light switches has the strongest impact as opposed to other controls. On the other hand, group norms and conformity intention are not significant predictors. Regarding demographics, men are more likely than women to perceive the IEQs to have positive impacts on their productivity, without considering other variables in the regression model; however, women are more likely than men to consider all IEQs as having positive impacts on productivity, after considering other variables. Furthermore, our findings provide suggestions for prioritizing wellness in the workplace since the early design stage.

99 GENERAL AND MISCELLANEOUS↗

DOE OSTI2022

Chronological changes in soil biogeochemical properties of the glacier foreland of Midtre Lovénbreen, Svalbard, attributed to soil-forming factors

We report that Glacier forelands provide an excellent opportunity to investigate vegetation succession and soil development along the chronosequence; however, there are few studies on soil biogeochemical changes from environmental factors, aside from time. This study aimed to investigate soil development and biogeochemical changes in the glacier foreland of Midtre Lovenbreen, Svalbard, by considering various factors, including time. Eighteen vegetation and soil variables were measured at 38 different sampling sites of varying soil age, depth, and glacio-fluvial activity. Soil organic matter (SOM) was quantitatively measured, and the compositional changes in SOM were determined following size-density fractionation. In the topsoil, the soil organic carbon (SOC) and total nitrogen (N) content was found to increase along the soil chronosequence and were highly correlated with vegetation-associated variables. These findings suggest that plant-derived material was the main driver of the light fraction of SOM accumulation in the topsoil. The heavy fractions of SOM were composed of microbially transformed organic compounds, eventually contributing to SOM stabilization within short 90-yr deglaciation under harsh climatic conditions. In addition to time, the soil vertical profiles showed that other environmental parameters, also affected the soil biogeochemical properties. The high total phosphorous (P) content and electrical conductivity in the topsoil were attributed to unweathered subglacial materials and a considerable amount of inorganic ions from subglacial meltwater. The high P and magnesium content in the subsoil were attributed to parent materials, while the high sodium and potassium content in the surface soil were a result of sea-salt deposition. Glacio-fluvial runoff hampered ecosystem development by inhibiting vegetation development and SOM accumulation. This study emphasizes the importance of considering various soil-forming factors, including parent/subglacial materials, aeolian deposition, and glacio-fluvial runoff, as well as soil age, to obtain a comprehensive understanding of the ecosystem development in glacier forelands.

glacio-fluvial runoff↗

DOE OSTI2024

Structural basis for inhibition of coagulation factor VIII reveals a shared antigenic hotspot on the C1 domain

Hemophilia A arises from dysfunctional or deficient coagulation factor (F)VIII and leads to inefficient fibrin clot formation and uncontrolled bleeding events. The development of antibody inhibitors is a clinical complication in hemophilia A patients receiving FVIII replacement therapy. LE2E9 is an anti-C1 domain inhibitor previously isolated from a mild/moderate hemophilia A patient and disrupts FVIII interactions with von Willebrand factor and FIXa, though the intermolecular contacts that underpin LE2E9-mediated FVIII neutralization are undefined. To determine the structure of the complex between FVIII and LE2E9 and characterize its mechanism of inhibition. FVIII was bound to the antigen binding fragment (Fab) of NB2E9, a recombinant construct of LE2E9, and its structure was determined by cryogenic electron microscopy. Here, this report communicates the 3.46 Å structure of FVIII bound to NB2E9, with its epitope comprising FVIII residues S2040 to Y2043, K2065 to W2070, and R2150 to H2155. Structural analysis reveals that the LE2E9 epitope overlaps with portions of the epitope for 2A9, a murine-derived inhibitor, suggesting that these residues represent a shared antigenic region on the C1 domain between FVIII –/– mice and hemophilia A patients. Furthermore, the FVIII:NB2E9 structure elucidates the orientation of the LE2E9 glycan, illustrating how the glycan sterically blocks interactions between the FVIII C1 domain and the von Willebrand factor D' domain. A putative model of the FVIIIa:FIXa complex suggests potential clashing between the NB2E9 glycan and FIXa light chain. These results describe an antigenic “hotspot” on the FVIII C1 domain and provide a structural basis for engineering FVIII replacement therapeutics with reduced antigenicity.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2026

Absorption dissymmetry factor enhancement: A data-driven approach to unravel the synthesis knobs of chiral 2D perovskites

Chiral 2D metal halide perovskites (MHPs) are promising for spin-optoelectronic applications, yet their absorption dissymmetry factor (g abs ) exhibits significant variability due to complex, co-dependent structural and experimental factors. Here, we established a data-driven framework using Pearson’s correlation, ANOVA, and Gaussian process regression to identify and model key synthesis “knobs” governing these properties. The analysis revealed that solvent choice is the primary factor driving variability. For acetonitrile-based films, g abs was maximized by optimizing annealing temperature and film thickness. Conversely, films from higher boiling point solvents showed complex dependencies on annealing temperature, excitonic integral intensity, and film texture. These statistical correlations provide a roadmap for the rational design of high-performance chiral MHPs and establish a foundation for future machine learning-driven material exploration.

ANOVA↗

DOE OSTI2025

Probing hard/soft factorization via beam-spin asymmetry in exclusive pion electroproduction from the proton

Deep exclusive meson production (DEMP) reactions, such as $p(\vec{e}, e' π^+)n$, provide opportunities to study the three-dimensional structure of the nucleon through differential cross section and beam- and target-spin asymmetry measurements. This work aims to probe the onset of the hard/soft factorization regime through the exclusive $p(\vec{e}, e' π^+)n$ reaction, as measured in the KaonLT experiment at Jefferson Lab Hall C. A 10.6 GeV longitudinally polarized electron beam was incident on an unpolarized liquid hydrogen target, and the scattered electron and produced meson were detected in two magnetic focusing spectrometers, enabling precision cross section measurements. The cross section ratio $σ_{LT'}/σ_0$ was extracted from the beam-spin asymmetry $A_{LU}$. The t -dependence of $σ_{LT'}/σ_0$ was determined at fixed $Q^2$ and $x_B$ over a range of kinematics from 2 < $Q^2$ < 6 GeV$^2$ above the resonance region ($W$ > 2 GeV). Furthermore, these data are combined with recent results from CLAS/CLAS12 to determine the $Q^2$-dependence of at two $(x_B, t)$ settings. This was fairly flat, with $Q^2$ not having a measurable effect on the value of in the range explored. Results are compared to predictions from the generalized parton distribution (GPD) formalism, which relies explicitly on hard/soft factorization, and Regge formalism. The Regge models better predict $σ_{LT'}/σ_0$, which suggests that the factorization regime is not yet reached.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2022

Convective heat transfer and friction factor characteristics of molten salts in spirally fluted tubes

Spirally fluted tubes have been widely used for heat exchangers due to their superior heat transfer enhancement. However, most of the previous studies focused on the effects of a limited number of geometric parameters, i.e., the flute pitch and flute depth, on convective heat transfer and friction factor characteristics of low-Prandtl-number fluids, i.e., air and water. The correlations developed in these studies may not be accurate or applicable for medium-Prandtl-number fluids, such as molten salts. A numerical analysis using a Computational Fluid Dynamics (CFD) tool, STAR–CCM+, is therefore carried out in this study to systematically investigate the effects of four geometric parameters, including the flute pitch ρ, flute depth e, flute start number N s (or flute helix angle θ), and trough length L tr on convective heat transfer and friction factor characteristics of a medium-Prandtl-number fluid, FLiNaK (46.5LiF-11.5NaF-42KF mol %), in spirally fluted tubes. Additionally, the convective heat transfer and Darcy friction factor correlations are proposed and validated, with ± 20% uncertainties, for medium-Prandtl-number fluids under the following conditions: Re = 88–1600, Pr = 2.5–40, ρ/D c = 0.44–3.51, e/D c = 0.10–0.40, θ/90= 0.20–0.81, and L tr /D c = 0.71–2.16. The correlations proposed help improve the design of spirally fluted-tube heat exchangers.

42 ENGINEERING↗

DOE OSTI2024

Enhancement of disposal efficiency for deep geological repositories based on three design factors - Decay heat optimization, increased thermal limit of the buffer and double-layer concept

This study investigates the enhancement of disposal efficiency for deep geological repositories (DGRs) based on three design factors: decay heat optimization, increased thermal limit of the buffer, and double-layer concept using coupled thermo-hydro-mechanical (THM) numerical simulations. Decay heat optimization is achieved by iteratively emplacing spent nuclear fuels having the maximum and minimum decay heat in a canister. Disposal areas can be reduced by 20 % to 40 % compared to the current reference disposal system in Korea (KRS+) in accordance with the combinations of the three design factors, alleviating challenges in site selection for the DGR. This study additionally identifies an optimal layer spacing of 500 m for the double-layer concept in the viewpoint of the buffer temperature, where thermal interaction between the upper and lower layers nearly disappears. However, determining the ultimate disposal and layer spacing requires engineering judgement, considering not only the thermal performance of the DGR but also various factors such as cost and difficulties of the construction and rock mass stability. DGRs designed with an increased thermal limit of the buffer poses a greater probability of rock mass failure around disposal tunnels and deposition holes due to elevated thermal stresses. Densely arranged heat sources for the DGRs with enhanced disposal efficiency lead to larger temperature increase even at the far-field scale, raising a possibility of thermally driven fracture shear activation with associated hydraulic, mechanical, and seismic changes.

58 GEOSCIENCES↗

DOE OSTI2021

HAND transcription factors cooperatively specify the aorta and pulmonary trunk

Congenital heart defects (CHDs) affecting the cardiac outflow tract (OFT) constitute a significant cause of morbidity and mortality. The OFT develops from migratory cell populations which include the cardiac neural crest cells (cNCCs) and secondary heart field (SHF) derived myocardium and endocardium. The related transcription factors HAND1 and HAND2 have been implicated in human CHDs involving the OFT. Although Hand1 is expressed within the OFT, Hand1 NCC-specific conditional knockout mice (H1CKOs) are viable. Here we show that these H1CKOs present a low penetrance of OFT phenotypes, whereas SHF-specific Hand1 ablation does not reveal any cardiac phenotypes. Further, HAND1 and HAND2 appear functionally redundant within the cNCCs, as a reduction/ablation of Hand2 on an NCC-specific H1CKO background causes pronounced OFT defects. Double conditional Hand1 and Hand2 NCC knockouts exhibit persistent truncus arteriosus (PTA) with 100% penetrance. NCC lineage-tracing and Sema3c in situ mRNA expression reveal that Sema3c-expressing cells are mis-localized, resulting in a malformed septal bridge within the OFTs of H1CKO;H2CKO embryos. Interestingly, Hand1 and Hand2 also genetically interact within the SHF, as SHF H1CKOs on a heterozygous Hand2 background exhibit Ventricular Septal Defects (VSDs) with incomplete penetrance. Previously, we identified a BMP, HAND2, and GATA-dependent Hand1 OFT enhancer sufficient to drive reporter gene expression within the nascent OFT and aorta. Using these transcription inputs as a probe, we identify a novel Hand2 OFT enhancer, suggesting that a conserved BMP-GATA dependent mechanism transcriptionally regulates both HAND factors. These findings support the hypothesis that HAND factors interpret BMP signaling within the cNCCs to cooperatively coordinate OFT morphogenesis.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2015

Pregnane and Xenobiotic Receptor gene expression in liver cells is modulated by Ets-1 in synchrony with transcription factors Pax5, LEF-1 and c-jun

Nuclear receptor PXR is predominantly expressed in liver and intestine. Expression of PXR is observed to be dysregulated in various metabolic disorders indicating its involvement in disease development. However, information available on mechanisms of PXR self-regulation is fragmentary. The present investigation identifies some of the regulatory elements responsible for its tight regulation and low cellular expression. Here, we report that the PXR-promoter is a target for some key transcription factors like PU.1/Ets-1, Pax5, LEF-1 and c-Jun. Interestingly, we observed that PXR-promoter responsiveness to Pax5, LEF-1 and c-Jun, is considerably enhanced by Ets transcription factors (PU.1 and Ets-1). Co-transfection of cells with Ets-1, LEF-1 and c-Jun increased PXR-promoter activity by 5-fold and also induced expression of endogenous human PXR. Site-directed mutagenesis and transfection studies revealed that two Ets binding sites and two of the three LEF binding sites in the PXR-promoter are functional and have a positive effect on PXR transcription. Results suggest that expression of Ets family members, in conjunction with Pax5, LEF-1 and c-Jun, lead to coordinated up-regulation of PXR gene transcription. Insights obtained on the regulation of PXR gene have relevance in offering important cues towards normal functioning as well as development of several metabolic disorders via PXR signaling. - Highlights: • The study identified cis-regulatory elements in the nuclear receptor PXR promoter. • Several trans-acting factors modulating the PXR-promoter have been identified. • PU.1/Ets-1, Pax5, LEF-1, c-Jun, LyF-VI and NF-1 act as modulators of the PXR-promoter. • Ets-1 in conjunction with LEF-1 and c-Jun exhibit 5-fold activation of the PXR-promoter. • Insights into PXR-regulation have relevance in normal and pathological conditions.

60 APPLIED LIFE SCIENCES↗