An acetyl-methyl switch drives a conformational change in p53

Individual posttranslational modifications (PTMs) of p53 mediate diverse p53-dependent responses; however, much less is known about the combinatorial action of adjacent modifications. Here, we describe crosstalk between the early DNA damage response mark p53K382me2 and the surrounding PTMs that modulate binding of p53 cofactors, including 53BP1 and p300. The 1.8 Å resolution crystal structure of the tandem Tudor domain (TTD) of 53BP1 in complex with p53 peptide acetylated at K381 and dimethylated at K382 (p53K381acK382me2) reveals that the dual PTM induces a conformational change in p53. The α-helical fold of p53K381acK382me2 positions the side chains of R379, K381ac, and K382me2 to interact with TTD concurrently, reinforcing a modular design of double PTM mimetics. Biochemical and nuclear magnetic resonance analyses show that other surrounding PTMs, including phosphorylation of serine/threonine residues of p53, affect association with TTD. Our findings suggest a novel PTM-driven conformation switch-like mechanism that may regulate p53 interactions with binding partners.

Suppression of Inflammatory Responses by Dihydromyricetin, a Flavonoid from Ampelopsis grossedentata, via Inhibiting the Activation of NF-κB and MAPK Signaling Pathways

Ampelopsis grossedentata, an indigenous plant in southern China, has been used for treating pharyngitis in traditional Chinese medicine for hundreds of years. In this study, we explored the anti-inflammatory activity of dihydromyricetin (1), its major bioactive component, and the underlying mechanism of this action. We demonstrated that 1 suppressed the levels of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) as well as increased the level of the anti-inflammatory cytokine interleukin-10 (IL-10) in lipopolysaccharide (LPS)-treated mice. Moreover, 1 was found to markedly inhibit the production of nitric oxide (NO) and the levels of TNF-α, IL-1β, and IL-6, whereas it increased the level of IL-10 in LPS-induced RAW 264.7 macrophage cells. Compound 1 also reduced the protein expression of inducible nitric oxide synthase (iNOS), TNF-α, and cyclooxygenase-2 (COX-2) in macrophage cells. Furthermore, 1 suppressed the phosphorylation of NF-kappa B (NF-κB) and IκBα as well as the phosphorylation of p38 and JNK but not ERK1/2 in LPS-stimulated macrophages. Taken together, the present results suggest that 1 exerts its topical anti-inflammatory action through suppressing the activation of NF-κB and the phosphorylation of p38 and JNK. Thus, 1 may be a potentially useful therapeutic agent for inflammatory-related diseases.

An insight into the heat and mass transfer mechanisms of eggshells hatching broiler chicks and its effects to the hatcher environment

Thermodynamic study of incubated eggs is an important component in the optimisation of incubation processes. However, research on the interaction of heat and moisture transfer mechanisms in eggs is rather limited and does not focus on the hatching stage of incubation. During hatch, both the recently hatched chick and the broken eggshell add extra heat and moisture contents to the hatcher environment. In this study, we have proposed a novel way to estimate thermodynamically the amount of water evaporated from a broken eggshell during hatch. The hypothesis of this study considers that previously reported drops in eggshell temperature during hatching of chicks is the result remaining water content evaporating from the eggshell, released on the inner membrane by the recently hatched wet chick, just before hatch. To reproduce this process, water was sprayed on eggshells to mimic the water-fluid from the wet body of a chick. For each sample of eggshell, the shell geometry and weight, surface area and eggshell temperature were measured. Water evaporation losses and convection coefficient were calculated using a novel model approach considering the simultaneous heat and mass transfer profiles in an eggshell. The calculated average convective coefficient was 23.9 ± 7.5 W/m(2) °C, similar to previously reported coefficients in literature as a function of 0.5-1m/s air speed range. Comparison between measured and calculated values for the water evaporation showed 68% probability accuracy, associated to the use of an experimentally derived single heat transfer coefficient. The results support our proposed modelling approach of heat and mass transfer mechanisms. Furthermore, by estimating the amount of evaporated water in an eggshell post-hatch, air humidity levels inside the hatcher can be optimised to ensure wet chicks dry properly while not dehydrating early hatching chicks.

Effect of species-specific sound stimulation on the development and hatching of broiler chicks

1. Previous research has reported that chicken embryos develop a functionary auditory system during incubation and that prenatal sound may play an important role in embryo development and alter the hatch time. In this study the effects of prenatal auditory stimulation on hatch process, hatch performance, the development of embryo and blood parameters were investigated. 2. Four batches of Ross 308 broiler breeder eggs were incubated either in control or in sound-stimulated groups. The sound-stimulated embryos were exposed to a discontinuous sound of species-specific calls by means of a speaker at 72 dB for 16 h a day: maternal calls from d 10 to d 19 of incubation time and embryo/chick calls from d 19 until hatching. The species-specific sound was excluded from the control group. 3. The onset of hatch was delayed in the sound-stimulated group compared to the controls. This was also supported by comparison of the exact hatching time of individual focal chicks within the two groups. However, the sound-stimulated embryos had a lower hatchability than the control group, mainly due to significantly increased numbers of late deaths. 4. The embryos exhibited a similar growth pattern between the sound-stimulated group and the control group. Although sound exposure decreased body weight at d 16, no consistent effect of sound on body weight at incubation stage was observed. Species-specific sound stimulation also had no impact on chick quality, blood values and plasma corticosterone concentrations during hatch.

Structural plasticity of methyllysine recognition by the tandem tudor domain of 53BP1

p53 is dynamically regulated through various posttranslational modifications (PTMs), which differentially modulate its function and stability. The dimethylated marks p53K370me2 and p53K382me2 are associated with p53 activation or stabilization and both are recognized by the tandem Tudor domain (TTD) of 53BP1, a p53 cofactor. Here we detail the molecular mechanisms for the recognition of p53K370me2 and p53K382me2 by 53BP1. The solution structures of TTD in complex with the p53K370me2 and p53K382me2 peptides show a remarkable plasticity of 53BP1 in accommodating these diverse dimethyllysine-containing sequences. We demonstrate that dimeric TTDs are capable of interacting with the two PTMs on a single p53K370me2K382me2 peptide, greatly strengthening the 53BP1-p53 interaction. Analysis of binding affinities of TTD toward methylated p53 and histones reveals strong preference of 53BP1 for p53K382me2, H4K20me2, and H3K36me2 and suggests a possible role of multivalent contacts of 53BP1 in p53 targeting to and accumulation at the sites of DNA damage.

Depletion of white adipocyte progenitors induces beige adipocyte differentiation and suppresses obesity development

Overgrowth of white adipose tissue (WAT) in obesity occurs as a result of adipocyte hypertrophy and hyperplasia. Expansion and renewal of adipocytes relies on proliferation and differentiation of white adipocyte progenitors (WAP); however, the requirement of WAP for obesity development has not been proven. Here, we investigate whether depletion of WAP can be used to prevent WAT expansion. We test this approach by using a hunter-killer peptide designed to induce apoptosis selectively in WAP. We show that targeted WAP cytoablation results in a long-term WAT growth suppression despite increased caloric intake in a mouse diet-induced obesity model. Our data indicate that WAP depletion results in a compensatory population of adipose tissue with beige adipocytes. Consistent with reported thermogenic capacity of beige adipose tissue, WAP-depleted mice display increased energy expenditure. We conclude that targeting of white adipocyte progenitors could be developed as a strategy to sustained modulation of WAT metabolic activity.

Effect of transportation duration of 1-day-old chicks on postplacement production performances and pododermatitis of broilers up to slaughter age

This experiment studied the effect of transportation duration of 1-d-old chicks on dehydration, mortality, production performance, and pododermatitis during the growout period. Eggs from the same breeder flock (Ross PM3) were collected at 35, 45, and 56 wk of age, for 3 successive identical experiments. In each experiment, newly hatched chicks received 1 of 3 transportation duration treatments from the hatchery before placement in the on-site rearing facility: no transportation corresponding to direct placement in less than 5 min (T00), or 4 (T04) or 10 h (T10) of transportation. The chicks were housed in 35-m(2) pens (650 birds each) and reared until 35 d old. Hematocrit and chick BW were measured on sample chicks before and after transportation. During the growout period, bird weight, feed uptake, and feed conversion ratio were measured weekly until slaughter. Transportation duration affected BW; T00 groups had a significantly higher BW than T04 and T10 transported birds but this effect lasted only until d 21. No clear effect on hematocrit, feed uptake, feed conversion ratio, or mortality was observed for birds transported up to 10 h. The decrease in weight in T10 birds was associated with less severe pododermatitis. Increasing age of the breeder flock was correlated with reduced egg fertility and hatchability, and also with higher quality and BW of hatched chicks. Chicks from older breeders also exhibited reduced mortality during the growout period.

Crystal design using multipolar electrostatic interactions: A concept study for organic electronics

Using a simple synthetic protocol, heterohexacene analogues with a quadrupolar distribution of partial charges are readily available. In contrast to most other acenes, these compounds crystallize with a slipped-stack, brickwork-like packing which is mainly controlled by electrostatic interactions. This type of packing offers an advantage for organic semiconductors, because it allows more isotropic charge transport compared to the “herring bone” stacking observed for other acenes.

Exchange of associated factors directs a switch in HBO1 acetyltransferase histone tail specificity

Histone acetyltransferases (HATs) assemble into multisubunit complexes in order to target distinct lysine residues on nucleosomal histones. Here, we characterize native HAT complexes assembled by the BRPF family of scaffold proteins. Their plant homeodomain (PHD)-Zn knuckle-PHD domain is essential for binding chromatin and is restricted to unmethylated H3K4, a specificity that is reversed by the associated ING subunit. Native BRPF1 complexes can contain either MOZ/MORF or HBO1 as catalytic acetyltransferase subunit. Interestingly, while the previously reported HBO1 complexes containing JADE scaffold proteins target histone H4, the HBO1-BRPF1 complex acetylates only H3 in chromatin. We mapped a small region to the N terminus of scaffold proteins responsible for histone tail selection on chromatin. Thus, alternate choice of subunits associated with HBO1 can switch its specificity between H4 and H3 tails. These results uncover a crucial new role for associated proteins within HAT complexes, previously thought to be intrinsic to the catalytic subunit.

Dido3 PHD modulates cell differentiation and division

Death Inducer Obliterator 3 (Dido3) is implicated in the maintenance of stem cell genomic stability and tumorigenesis. Here, we show that Dido3 regulates the expression of stemness genes in embryonic stem cells through its plant homeodomain (PHD) finger. Binding of Dido3 PHD to histone H3K4me3 is disrupted by threonine phosphorylation that triggers Dido3 translocation from chromatin to the mitotic spindle. The crystal structure of Dido3 PHD in complex with H3K4me3 reveals an atypical aromatic-cage-like binding site that contains a histidine residue. Biochemical, structural, and mutational analyses of the binding mechanism identified the determinants of specificity and affinity and explained the inability of homologous PHF3 to bind H3K4me3. Together, our findings reveal a link between the transcriptional control in embryonic development and regulation of cell division.

MicroRNA-145 inhibits the growth, invasion, metastasis and angiogenesis of neuroblastoma cells through targeting hypoxia-inducible factor 2 alpha

Recent evidence shows that hypoxia-inducible factor 2 alpha (HIF-2α) may have critical roles in the growth and progression of neuroblastoma (NB) under non-hypoxic conditions. However, the underlying mechanisms and clinical potentials of normoxic HIF-2α expression in NB still remain largely unknown. In this study, HIF-2α immunostaining was identified in 26/42 NB tissues, which was correlated with clinicopathological features. In subtotal 20 NB cases, microRNA-145 (miR-145) was downregulated and inversely correlated with HIF-2α expression. Bioinformatics analysis revealed a putative miR-145 binding site in the 3'-untranslated region (3'-UTR) of HIF-2α messenger RNA (mRNA). Overexpression or knockdown of miR-145 responsively altered both the mRNA and protein levels of HIF-2α and its downstream genes, cyclin D1, matrix metalloproteinase 14 and vascular endothelial growth factor, in normoxically cultured NB cell lines SH-SY5Y and SK-N-SH. In a luciferase reporter system, miR-145 downregulated the luciferase activity of HIF-2α 3'-UTR, and these effects were abolished by a mutation in the putative miR-145-binding site. Overexpression of miR-145 suppressed the growth, invasion, metastasis and angiogenesis of SH-SY5Y and SK-N-SH cells in vitro and in vivo, while restoration of HIF-2α expression rescued the tumor cells from miR-145-mediated defects in these biological features. Furthermore, anti-miR-145 inhibitor rescued the HIF-2α knockdown-mediated repression on the growth, migration, invasion and angiogenesis of NB cells. These data indicate that miR-145 suppresses HIF-2α expression via the binding site in the 3'-UTR under normoxic conditions, thus inhibiting the aggressiveness and angiogenesis of NB.

Identification of complex vertebral malformation carriers in Holstein cattle in south China

Complex vertebral malformation (CVM) is a recently described monogenic autosomal recessive hereditary defect of Holstein dairy cattle that causes premature birth, aborted fetuses and stillborn calves. Guanine is substituted by thymine (G>T) in the solute carrier family 35 member A3 gene (SLC35A3). A valine is changed to a phenylalanine at position 180 of uridine 5'-diphosphate-N-acetyl-glucosamine transporter protein. CVM is expected to occur in many countries due to the widespread use of sire semen. We developed a created restriction site PCR (CRS-PCR) method to diagnose CVM in dairy cows. This was tested on 217 cows and 125 bulls selected randomly from a Holstein cattle population in south China. Five Holstein cows and five Holstein bulls were identified to be CVM carriers; the percentages of CVM carriers were estimated to be 2.3, 4.0 and 2.9% in the cows, bulls and entire Holstein cattle sample, respectively.

Deacetylation of FOXO3 by SIRT1 or SIRT2 leads to Skp2-mediated FOXO3 ubiquitination and degradation

Sirtuin deacetylases and FOXO (Forkhead box, class O) transcription factors have important roles in many biological pathways, including cancer development. SIRT1 and SIRT2 deacetylate FOXO factors to regulate FOXO function. Because acetylation and ubiquitination both modify the ɛ-amino group of lysine residues, we investigated whether FOXO3 deacetylation by SIRT1 or SIRT2 facilitates FOXO3 ubiquitination and subsequent proteasomal degradation. We found that SIRT1 and SIRT2 promote FOXO3 poly-ubiquitination and degradation. Proteasome-inhibitor treatment prevented sirtuin-induced FOXO3 degradation, indicating that this process is proteasome dependent. In addition, we demonstrated that E3 ubiquitin ligase subunit Skp2 binds preferentially to deacetylated FOXO3. Overexpression of Skp2 caused poly-ubiquitination of FOXO3 and degradation, whereas knockdown of Skp2 increased the amount of FOXO3 protein. We also present evidence that SCF-Skp2 ubiquitinates FOXO3 directly in vitro. Furthermore, mutating four known acetylated lysine residues (K242, K259, K290 and K569) of FOXO3 into arginines to mimic deacetylated FOXO3 resulted in enhanced Skp2 binding but with inhibition of FOXO3 ubiquitination; this suggests that some or all of these four lysine residues are likely the sites for ubiquitination. In the livers of mice deficient in SIRT1, we detected increased expression of FOXO3, indicating SIRT1 regulates FOXO3 protein levels in vivo. Furthermore, we found that the elevation of SIRT1 and Skp2 expression in malignant PC3 and DU145 prostate cells is responsible for the downregulation of FOXO3 protein levels in these cells. Taken together, our data support the notion that deacetylation of FOXO3 by SIRT1 or SIRT2 facilitates Skp2-mediated FOXO3 poly-ubiquitination and proteasomal degradation.