Human Vav1 Expression in Hematopoietic and Cancer Cell Lines Is Regulated by c-Myb and by CpG Methylation

Vav1 is a signal transducer protein that functions as a guanine nucleotide exchange factor for the Rho/Rac GTPases in the hematopoietic system where it is exclusively expressed. Recently, Vav1 was shown to be involved in several human malignancies including neuroblastoma, lung cancer, and pancreatic ductal adenocarcinoma (PDA). Although some factors that affect vav1 expression are known, neither the physiological nor pathological regulation of vav1 expression is completely understood. We demonstrate herein that mutations in putative transcription factor binding sites at the vav1 promoter affect its transcription in cells of different histological origin. Among these sites is a consensus site for c-Myb, a hematopoietic-specific transcription factor that is also found in Vav1-expressing lung cancer cell lines. Depletion of c-Myb using siRNA led to a dramatic reduction in vav1 expression in these cells. Consistent with this, co-transfection of c-Myb activated transcription of a vav1 promoter-luciferase reporter gene construct in lung cancer cells devoid of Vav1 expression. Together, these results indicate that c-Myb is involved in vav1 expression in lung cancer cells. We also explored the methylation status of the vav1 promoter. Bisulfite sequencing revealed that the vav1 promoter was completely unmethylated in human lymphocytes, but methylated to various degrees in tissues that do not normally express vav1. The vav1 promoter does not contain CpG islands in proximity to the transcription start site; however, we demonstrated that methylation of a CpG dinucleotide at a consensus Sp1 binding site in the vav1 promoter interferes with protein binding in vitro. Our data identify two regulatory mechanisms for vav1 expression: binding of c-Myb and CpG methylation of 5′ regulatory sequences. Mutation of other putative transcription factor binding sites suggests that additional factors regulate vav1 expression as well

Runx1 is required for the endothelial to haematopoietic cell transition but not thereafter

HSCs are the founder cells of the adult hematopoietic system, and thus knowledge of the molecular program directing their generation during development is important for regenerative hematopoietic strategies. Runx1 is a pivotal transcription factor required for HSC generation in the vascular regions of the mouse conceptus - the aorta, vitelline and umbilical arteries, yolk sac and placenta 1, 2. It is thought that HSCs emerge from vascular endothelial cells through the formation of intra-arterial clusters 3 and that Runx1 functions during the transition from ‘hemogenic endothelium’ to HSCs 4, 5. Here we show by conditional deletion that Runx1 activity in vascular endothelial cadherin (VEC) positive endothelial cells is indeed essential for intra-arterial cluster, hematopoietic progenitor, and HSC formation. In contrast, Runx1 is not required in cells expressing Vav, one of the first pan-hematopoietic genes expressed in HSCs. Collectively these data show that Runx1 function is essential in endothelial cells for hematopoietic progenitor and HSC formation from the vasculature, but its requirement ends once or before Vav is expressed

Measurement of the time-integrated CPCP asymmetry in D0→KS0KS0D^0 \to K^0_S K^0_S decays

The time-integrated $CP$ asymmetry in the decay $D^0 \to K^0_S K^0_S$ is measured using $3 fb^{-1}$ of proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The flavour of the $D^0$ meson is determined by use of the decay $D^{*+} \to D^0 \pi^+$ and its charge conjugate mode. The result is $${\cal A}_{CP} = -0.029 \pm 0.052 \pm 0.022,$$ where the first uncertainty is statistical and the second systematic. The result is consistent with Standard Model expectations and improves the uncertainty with respect to the only previous measurement of this quantity by more than a factor of three.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-030.htm

Measurement of the electron reconstruction efficiency at LHCb

The single electron track-reconstruction efficiency is calibrated using a sample corresponding to 1.3 fb−1 of pp collision data recorded with the LHCb detector in 2017. This measurement exploits B+→ J/ψ(e+e−)K+ decays, where one of the electrons is fully reconstructed and paired with the kaon, while the other electron is reconstructed using only the information of the vertex detector. Despite this partial reconstruction, kinematic and geometric constraints allow the B meson mass to be reconstructed and the signal to be well separated from backgrounds. This in turn allows the electron reconstruction efficiency to be measured by matching the partial track segment found in the vertex detector to tracks found by LHCb's regular reconstruction algorithms. The agreement between data and simulation is evaluated, and corrections are derived for simulated electrons in bins of kinematics. These correction factors allow LHCb to measure branching fractions involving single electrons with a systematic uncertainty below 1%

Study of the ψ2(3823)ψ_2(3823) and χc1(3872)χ_{c1}(3872) states in B+→(Jψπ+π−)K+B^+ \rightarrow \left( Jψπ^+π^-\right)K^+ decays

The decays $B^+\rightarrow J/\psi \pi^+ \pi^- K^+$ are studied using a data set corresponding to an integrated luminosity of 9fb$^{-1}$ collected with the LHCb detector in proton-proton collisions between 2011 and 2018. Precise measurements of the ratios of branching fractions with the intermediate $\psi_2(3823)$, $\chi_{c1}(3872)$ and $\psi(2S)$ states are reported. The decay of $B^+\rightarrow \psi_2(3823)K^+$ with $\psi_2(3823)\rightarrow J\psi\pi^+\pi^-$ is observed for the first time with a significance of 5.1 standard deviations. The mass differences between the $\psi_2(3823)$, $\chi_{c1}(3872)$ and $\psi(2S)$ states are measured to be $$\begin{array}{rcl} m_{\chi_{c1(3872)}} - m_{\psi_2(3823)} &= & 47.50 \pm 0.53 \pm 0.13\,\mathrm{MeV/}c^2\,, \\ m_{\psi_2(3823)} - m_{\psi(2S)} &= & 137.98 \pm 0.53 \pm 0.14\,\mathrm{MeV/}c^2\,, \\ m_{\chi_{c1}(3872)} - m_{\psi(2S)} &= & 185.49 \pm 0.06 \pm 0.03\,\mathrm{MeV/}c^2\,, \end{array}$$ resulting in the most precise determination of the $\chi_{c1}(3782)$ mass. The width of the $\psi_2(3823)$ state is found to be below 5.2MeV at 90\% confidence level. The Breit-Wigner width of the $\chi_{c1}(3872)$ state is measured to be $$\Gamma^{\mathrm{BW}}_{\chi_{c1}(3872)} = 0.96^{+0.19}_{-0.18}\pm0.21 \mathrm{MeV},$$ which is inconsistent with zero by 5.5 standard deviations

Umbilical venous IGF-1 concentration, neonatal bone mass, and body composition

IGF-1 is a key growth factor during fetal life. Using DXA, we found that the concentration of IGF-1 in umbilical cord serum is strongly related to neonatal whole body bone mineral content, lean mass, and fat mass. However IGF-1 did not explain the relationships of maternal smoking, fat mass, and physical activity with neonatal bone mass. The study supports a direct role for circulating IGF-1 in growth of the fetal skeleton. INTRODUCTION: Evidence is accumulating that the risk of osteoporosis in later life may be determined in part by environmental influences during intrauterine and early postnatal life. We previously reported that maternal birthweight, smoking, fat stores, and physical activity during pregnancy predict neonatal bone mass. While the growth hormone/insulin-like growth factor 1 (GH/IGF-1) axis is an important determinant of postnatal skeletal growth, there are few data relating the concentration of growth factors in umbilical cord blood to bone mineral content (BMC) and other indices of body composition in the newborn infant. MATERIALS AND METHODS: We conducted a population-based study in a cohort of full-term, newborn infants whose mothers were characterized for lifestyle, body composition, and nutrition through their normal pregnancies. In a sample of 119 infants from the cohort, we related cord serum IGF-1 and insulin-like growth factor binding protein (IGFBP)-3 concentrations to neonatal body composition measured by DXA and evaluated the extent to which this cytokine mediates the previously reported effects of maternal diet and lifestyle on neonatal bone mass. RESULTS: There were strong positive associations between cord serum IGF-1 concentration and whole body BMC (r = 0.38, p < 0.001), whole body lean mass (r = 0.40, p < 0.001), and whole body fat mass (r = 0.50, p < 0.001) after adjusting for gestational age and sex. There was no association between cord serum IGF-1 and BMC adjusted for bone size. Neither cord serum IGF-1 nor IGFBP-3 explained the relationships that we previously reported between maternal influences and neonatal bone mass. CONCLUSIONS: Cord serum IGF-1 is more closely related to the size of the neonatal skeleton than to its degree of mineralization. Documented maternal determinants of neonatal bone mass seem to mediate their effects independently of variations in cord serum IGF-1 in healthy pregnancies