Developmental programming of tumor suppressor gene penetrance

Epidemiological studies have led to the hypothesis that major risk factors for developing diseases such as hypertension, cardiovascular disease and adult-onset diabetes are established during development. This developmental programming hypothesis proposes that exposure to an adverse stimulus or insult at critical, sensitive periods of development can induce permanent alterations in normal physiological processes that lead to increased disease risk later in life. For cancer, inheritance of a tumor suppressor gene defect confers a high relative risk for disease development. However, these defects are rarely 100% penetrant. Traditionally, gene-environment interactions are thought to contribute to the penetrance of tumor suppressor gene defects by facilitating or inhibiting the acquisition of additional somatic mutations required for tumorigenesis. The studies presented herein identify developmental programming as a distinctive type of gene-environment interaction that can enhance the penetrance of a tumor suppressor gene defect in adult life. Using rats predisposed to uterine leiomyoma due to a germ-line defect in one allele of the tuberous sclerosis complex 2 (Tsc-2) tumor suppressor gene, these studies show that early-life exposure to the xenoestrogen, diethylstilbestrol (DES), during development of the uterus increased tumor incidence, multiplicity and size in genetically predisposed animals, but failed to induce tumors in wild-type rats. Uterine leiomyomas are ovarian-hormone dependent tumors that develop from the uterine myometrium. DES exposure was shown to developmentally program the myometrium, causing increased expression of estrogen-responsive genes prior to the onset of tumors. Loss of function of the normal Tsc-2 allele remained the rate-limiting event for tumorigenesis; however, tumors that developed in exposed animals displayed an enhanced proliferative response to ovarian steroid hormones relative to tumors that developed in unexposed animals. Furthermore, the studies presented herein identify developmental periods during which target tissues are maximally susceptible to developmental programming. These data suggest that exposure to environmental factors during critical periods of development can permanently alter normal physiological tissue responses and thus lead to increased disease risk in genetically susceptible individuals. ^

Cis-acting elements and developmental regulators govern toxin gene expression in Bacillus anthracis

Expression of the structural genes for the anthrax toxin proteins is coordinately controlled by host-related signals such as elevated CO2 , and the trans-acting positive regulator, AtxA. No specific binding of AtxA to the toxin gene promoters has been demonstrated and no sequence-based similarities are apparent in the promoter regions of toxin genes. We hypothesized that the toxin genes possess common structural features that are required for positive regulation. To test this hypothesis, I performed an extensive characterization of the toxin gene promoters. I determined the minimal sequences required for atxA-mediated toxin gene expression and compared these sequences for structural similarities. In silico modeling and in vitro experiments indicated significant curvature within these regions. Random mutagenesis revealed that point mutations associated with reduced transcriptional activity, mostly mapped to areas of high curvature. This work enabled the identification of two potential cis-acting elements implicated in AtxA-mediated regulation of the toxin genes. In addition to the growth condition requirements and AtxA, toxin gene expression is under growth phase regulation. The transition state regulator AbrB represses atxA expression to influence toxin synthesis. Here I report that toxin gene expression also requires sigH, a gene encoding the RNA polymerase sigma factor associated with development in B. subtilis. In the well-studied B. subtilis system, σH is part of a feedback control pathway that involves AbrB and the major response regulator of sporulation initiation, Spo0A. My data indicate that in B. anthracis, regulatory relationships exist between these developmental regulators and atxA . Interestingly, during growth in toxin-inducing conditions, sigH and abrB expression deviates from that described for B. subtilis, affecting expression of the atxA gene. These findings, combined with previous observations, suggest that the steady state level of atxA expression is critical for optimal toxin gene transcription. I propose a model whereby, under toxin-inducing conditions, control of toxin gene expression is fine-tuned by the independent effects of the developmental regulators on the expression of atxA . The growth condition-dependent changes in expression of these regulators may be crucial for the correct timing and uninterrupted expression of the toxin genes during infection. ^

The relationship between risk perception and ethnicity as an explanation for late stage skin cancer diagnosis in Black and Hispanic populations: An analysis using data from the 2005 Health Information and National Trends Survey

Objective. The purpose of this study was to determine the relationship between ethnicity and skin cancer risk perception while controlling for other risk factors: education, gender, age, access to healthcare, family history of skin cancer, fear, and worry. ^ Methods. This study utilized the Health Information National Trends Survey (HINTS) dataset, a nationally representative sample of 5,586 individuals 18 years of age or older. One third of the respondents were chosen at random and asked questions involving skin cancer. Analysis was based on questions that identified skin cancer risk perception, fear of finding skin cancer, and frequency of worry about skin cancer and a variety of sociodemographic factors. ^ Results. Ethnicity had a significant impact on risk perception scores while controlling for other risk factors. Other risk factors that also had a significant impact on risk perception scores included family history of skin cancer, age, and worry. ^

A descriptive study of the sociodemographic, health and developmental factors associated with slow learning in children from upper to middle social class families in Texas

"Slow Learners" is a term used to describe children with an IQ range of 70-89 on a standardized individual intelligence test (i.e. with a standard deviation of either 15 or 16). They have above retarded, but below average intelligence and potential to learn. If the factors associated with the etiology of slow learning in children can be identified, it may be possible to hypothesize causal relationships which can be tested by intervention studies specifically designed to prevent slow learning. If effective, these may ultimately reduce the incidence of school dropouts and their cost to society. To date, there is little information about variables which may be etiologically significant. In an attempt to identify such etiologic factors this study examines the sociodemographic characteristics, prenatal history (hypertension, smoking, infections, medication, vaginal bleeding, etc.), natal history (length of delivery, Apgar score, birth trauma, resuscitation, etc.), neonatal history (infections, seizures, head trauma, etc.), developmental history (health problems, developmental milestones and growth during infancy and early childhood), and family history (educational level of the parents, occupation, history of similar condition in the family, etc.) of a series of children defined as slow learners. The study is limited to children from middle to high socioeconomic families in order to exclude the possible confounding variable of low socioeconomic status, and because a descriptive study of this group has not been previously reported. ^

Developmental functions of XKaiso, a transcriptional repressor associating with the p120 catenin in Xenopus laevis

The Armadillo family catenin proteins function in multiple capacities including cadherin-mediated cell-cell adhesion and nuclear signaling. The newest catenin, p120 catenin, differs from the classical catenins and binds to the membrane-proximal domain of cadherins. Recently, a novel transcription factor Kaiso was found to interact with p120 catenin, suggesting that p120 catenin also possesses a nuclear function. We isolated the Xenopus homolog of Kaiso, XKaiso, from a Xenopus stage 17 cDNA library. XKaiso contains an amino-terminal BTB/POZ domain and three carboxyl-terminal zinc fingers. The XKaiso transcript was present maternally and expressed throughout early embryonic development. XKaiso's spatial expression was defined via in situ hybridization and was found localized to the brain, eye, ear, branchial arches, and spinal cord. Co-immunoprecipitation of Xenopus p120 catenin and XKaiso demonstrated their mutual association, while related experiments employing differentially epitope-tagged XKaiso constructs suggest that XKaiso also self-associates. On the functional level, reporter assays employing a chimera of XKaiso fused to the GAL4 DNA binding domain indicated that XKaiso is a transcriptional repressor. To better understand the significance of the Kaiso-p120 catenin complex in vertebrate development, Kaiso knock-down experiments were undertaken, and the modulatory role of p120 catenin in Kaiso function examined during Xenopus development. Using morpholino antisense oligonucleotides to block translation of XKaiso, XKaiso was found to be essential for Xenopus gastrulation, being required for correct morphogenetic movements in early embryogenesis. Molecular marker analyses indicated that one target gene of the Wnt/β-catenin pathway, Siamois, is significantly increased in embryos depleted for XKaiso, while other dorsal, ventral, and mesodermal cell fate markers were unaltered. In addition, the non-canonical Wnt-11, known to participate in planar cell polarity/convergent extension processes, was significantly upregulated following depletion of XKaiso. Such increased Wnt-11 expression likely contributed to the XKaiso depletion phenotype because a dominant negative form of Wnt-11 or of the downstream effector Dishevelled partially rescued the observed gastrulation defects. These results show that XKaiso is essential for proper gastrulation movements, resulting at least in part from its modulation of non-canonical Wnt signaling. The significance of the XKaiso-p120 catenin interaction has yet to be determined, but appears to include a role in modulating genes promoting canonical and non-canonical Wnt signals. ^

Elevated pCO2 causes developmental delay in early larval Pacific oysters, Crassostrea gigas

Increasing atmospheric CO2 equilibrates with surface seawater, elevating the concentration of aqueous hydrogen ions. This process, ocean acidification, is a future and contemporary concern for aquatic organisms, causing failures in Pacific oyster (Crassostrea gigas) aquaculture. This experiment determines the effect of elevated pCO2 on the early development of C. gigas larvae from a wild Pacific Northwest population. Adults were collected from Friday Harbor, Washington, USA (48°31.7' N, 12°1.1' W) and spawned in July 2011. Larvae were exposed to Ambient (400 µatm CO2), MidCO2 (700 µatm), or HighCO2 (1,000 µatm). After 24 h, a greater proportion of larvae in the HighCO2 treatment were calcified as compared to Ambient. This unexpected observation is attributed to increased metabolic rate coupled with sufficient energy resources. Oyster larvae raised at HighCO2 showed evidence of a developmental delay by 3 days post-fertilization, which resulted in smaller larvae that were less calcified.

Spider crab Hyas araneus larval dry weight, C/N ratio and developmental time during experiments from different latitudes (54° vs 79°N), 2010

The combined impacts of future scenarios of ocean acidification and global warming on the larvae of a cold-eurythermal spider crab, Hyas araneus L., were investigated in one of its southernmost populations (living around Helgoland, southern North Sea, 54°N) and one of the northernmost populations (Svalbard, North Atlantic, 79°N). Larvae were exposed at temperatures of 3, 9 and 15°C to present day normocapnia (380 ppm CO2) and to CO2 conditions expected for the near or medium-term future (710 ppm by 2100 and 3000 ppm CO2 by 2300 and beyond). Larval development time and biochemical composition were studied in the larval stages Zoea I, II, and Megalopa. Permanent differences in instar duration between both populations were detected in all stages, likely as a result of evolutionary temperature adaptation. With the exception of Zoea II at 3°C and under all CO2 conditions, development in all instars from Svalbard was delayed compared to those from Helgoland, under all conditions. Most prominently, development was much longer and fewer specimens morphosed to the first crab instar in the Megalopa from Svalbard than from Helgoland. Enhanced CO2 levels (710 and particularly 3000 ppm), caused extended duration of larval development and reduced larval growth (measured as dry mass) and fitness (decreasing C/N ratio, a proxy of the lipid content). Such effects were strongest in the zoeal stages in Svalbard larvae, and during the Megalopa instar in Helgoland larvae.

Human midbrain precursors activate the expected developmental genetic program and differentiate long-term to functional A9 dopamine neurons in vitro. Enhancement by Bcl-XL

Understanding the molecular programs of the generation of human dopaminergic neurons (DAn) from their ventral mesencephalic (VM) precursors is of key importance for basic studies, progress in cell therapy, drug screening and pharmacology in the context of Parkinson's disease. The nature of human DAn precursors in vitro is poorly understood, their properties unstable, and their availability highly limited. Here we present positive evidence that human VM precursors retaining their genuine properties and long-term capacity to generate A9 type Substantia nigra human DAn (hVM1 model cell line) can be propagated in culture. During a one month differentiation, these cells activate all key genes needed to progress from pro-neural and prodopaminergic precursors to mature and functional DAn. For the first time, we demonstrate that gene cascades are correctly activated during differentiation, resulting in the generation of mature DAn. These DAn have morphological and functional properties undistinguishable from those generated by VM primary neuronal cultures. In addition, we have found that the forced expression of Bcl-XL induces an increase in the expression of key developmental genes (MSX1, NGN2), maintenance of PITX3 expression temporal profile, and also enhances genes involved in DAn long-term function, maintenance and survival (EN1, LMX1B, NURR1 and PITX3). As a result, Bcl-XL anticipates and enhances DAn generation.

Developmental Expression of Kv Potassium Channels at the Axon Initial Segment of Cultured Hippocampal Neurons

Axonal outgrowth and the formation of the axon initial segment (AIS) are early events in the acquisition of neuronal polarity. The AIS is characterized by a high concentration of voltage-dependent sodium and potassium channels. However, the specific ion channel subunits present and their precise localization in this axonal subdomain vary both during development and among the types of neurons, probably determining their firing characteristics in response to stimulation. Here, we characterize the developmental expression of different subfamilies of voltage-gated potassium channels in the AISs of cultured mouse hippocampal neurons, including subunits Kv1.2, Kv2.2 and Kv7.2. In contrast to the early appearance of voltage-gated sodium channels and the Kv7.2 subunit at the AIS, Kv1.2 and Kv2.2 subunits were tethered at the AIS only after 10 days in vitro. Interestingly, we observed different patterns of Kv1.2 and Kv2.2 subunit expression, with each confined to distinct neuronal populations. The accumulation of Kv1.2 and Kv2.2 subunits at the AIS was dependent on ankyrin G tethering, it was not affected by disruption of the actin cytoskeleton and it was resistant to detergent extraction, as described previously for other AIS proteins. This distribution of potassium channels in the AIS further emphasizes the heterogeneity of this structure in different neuronal populations, as proposed previously, and suggests corresponding differences in action potential regulation.

Iron distribution through the developmental stages of Medicago truncatula nodules.

Paramount to symbiotic nitrogen fixation (SNF) is the synthesis of a number of metalloenzymes that use iron as a critical component of their catalytical core. Since this process is carried out by endosymbiotic rhizobia living in legume root nodules, the mechanisms involved in iron delivery to the rhizobia-containing cells are critical for SNF. In order to gain insight into iron transport to the nodule, we have used synchrotron-based X-ray fluorescence to determine the spatio-temporal distribution of this metal in nodules of the legume Medicago truncatula with hitherto unattained sensitivity and resolution. The data support a model in which iron is released from the vasculature into the apoplast of the infection/differentiation zone of the nodule (zone II). The infected cell subsequently takes up this apoplastic iron and delivers it to the symbiosome and the secretory system to synthesize ferroproteins. Upon senescence, iron is relocated to the vasculature to be reused by the shoot. These observations highlight the important role of yet to be discovered metal transporters in iron compartmentalization in the nodule and in the recovery of an essential and scarce nutrient for flowering and seed production.

Explanation of changes in real estate stock market

The aim of this study is to explain the changes in the real estate prices as well as in the real estate stock market prices, using some macro-economic explanatory variables, such as the gross domestic product (GDP), the real interest rate and the unemployment rate. Several regressions have been carried out in order to express some types of incremental and absolute deflated real estate lock market indexes in terms of the macro-economic variables. The analyses are applied to the Swedish economy. The period under study is 1984-1994. Time series on monthly data are used. i.e. the number of data-points is 132. If time leads/lags are introduced in the e regressions, significant improvements in the already high correlations are achieved. The signs of the coefficients for IR, UE and GDP are all what one would expect to see from an economic point of view: those for GDP are all positive, those for both IR and UE are negative. All the regressions have high R2 values. Both markets anticipate change in the unemployment rate by 6 to 9 months, which seems reasonable because such change can be forecast quite reliably. But, on the contrary, there is no reason why they should anticipate by 3-6 months changes in the interest rate that can hardly be reliably forecast so far in advance.