A Tet-on system for DRD1-expressing cells

Inducible overexpression of a FAM3C/ILEI transgene has pleiotropic effects with shortened life span, liver fibrosis and anemia in mice

FAM3C/ILEI is an important factor in epithelial-to-mesenchymal transition (EMT) induction, tumor progression and metastasis. Overexpressed in many cancers, elevated ILEI levels and secretion correlate with poor patient survival. Although ILEI's causative role in invasive tumor growth and metastasis has been demonstrated in several cellular tumor models, there are no available transgenic mice to study these effects in the context of a complex organism. Here, we describe the generation and initial characterization of a Tet-ON inducible Fam3c/ILEI transgenic mouse strain. We find that ubiquitous induction of ILEI overexpression (R26-ILEIind) at weaning age leads to a shortened lifespan, reduced body weight and microcytic hypochromic anemia. The anemia was reversible at a young age within a week upon withdrawal of ILEI induction. Vav1-driven overexpression of the ILEIind transgene in all hematopoietic cells (Vav-ILEIind) did not render mice anemic or lower overall fitness, demonstrating that no intrinsic mechanisms of erythroid development were dysregulated by ILEI and that hematopoietic ILEI hyperfunction did not contribute to death. Reduced serum iron levels of R26-ILEIind mice were indicative for a malfunction in iron uptake or homeostasis. Accordingly, the liver, the main organ of iron metabolism, was severely affected in moribund ILEI overexpressing mice: increased alanine transaminase and aspartate aminotransferase levels indicated liver dysfunction, the liver was reduced in size, showed increased apoptosis, reduced cellular iron content, and had a fibrotic phenotype. These data indicate that high ILEI expression in the liver might reduce hepatoprotection and induce liver fibrosis, which leads to liver dysfunction, disturbed iron metabolism and eventually to death. Overall, we show here that the novel Tet-ON inducible Fam3c/ILEI transgenic mouse strain allows tissue specific timely controlled overexpression of ILEI and thus, will serve as a versatile tool to model the effect of elevated ILEI expression in diverse tissue entities and disease conditions, including cancer.

Profiling transcriptomic responses of human stem cell-derived medium spiny neuron-like cells to exogenous phasic and tonic neurotransmitters

Transcriptomic responses to neurotransmitters contribute to the complex processes driving memory and addiction. Advances in both measurement methods and experimental models continue to improve our understanding of this regulatory layer. Here we focus on the experimental potential of stem cell derived neurons, currently the only ethical model that can be used in reductionist and experimentally perturbable studies of human cells. Prior work has focused on generating distinct cell types from human stem cells, and has also shown their utility in modeling development and cellular phenotypes related to neurodegeneration. Here we seek an understanding of how stem cell derived neural cultures respond to perturbations experienced during development and disease progression. This work profiles transcriptomic responses of human medium spiny neuron-like cells with three specific goals. We first characterize transcriptomic responses to dopamine and dopamine receptor agonists and antagonists presented in dosing patterns mimicking acute, chronic, and withdrawal regimens. We also assess transcriptomic responses to low and persistent tonic levels of dopamine, acetylcholine, and glutamate to better mimic the in vivo environment. Finally, we identify similar and distinct responses between hMSN-like cells derived from H9 and H1 stem cell lines, providing some context for the extent of variability these types of systems will likely pose for experimentalists. The results here suggest future optimizations of human stem cell derived neurons to increase their in vivo relevance and the biological insights that can be garnered from these models.

How Consistent are Genetic Factors in Explaining Leisure-Time Physical Activity and Sport Participation? The Portuguese Healthy Families Study

This study investigates how consistent genetic factors are, as measured by heritability estimates (h2), in the leisure-time physical activity index (LTPAI) and sport participation index (SPI) from early (10-14 yrs) to late adolescence (15-19 yrs). The sample comprises 12,385 subjects from 3,378 Portuguese nuclear families. Height and weight were measured and body mass index (BMI) was calculated, and the LTPAI and SPI were estimated by questionnaire. Socioeconomic status (SES) was assessed by parental occupation. Analyses were done using S.A.G.E. software. Our results showed that h2 estimates for the LTPAI and SPI in the two age groups (10-14 yrs and 15-19 yrs) were stable: for the LTPAI, h2 = 0.297 and 0.322, respectively; and for the SPI, h2 = 0.413 and 0.428, respectively. Sibling correlations and environmental correlations are higher in the younger age group for both the LTPAI and the SPI. Spousal correlations are higher in the younger age group for the LTPAI and lower for the SPI than the older group. Parent-offspring correlations are similar in both age groups for the LTPAI and SPI. In conclusion, the influence of genetic factors on physical activity and sport participation remains stable across age in adolescence. However, variation in sibling correlations - in particular, environmental correlations - was observed. These findings suggest that shared/non-shared environmental factors express different degrees of importance across age. Future intervention programs aiming to promote change in behaviors need to consider these results to bring about positive changes in physical activity and sport participation behaviors within the family setting.

Sucrose withdrawal induces depression and anxiety-like behavior by Kir2.1 upregulation in the nucleus accumbens

Dieting induces depression and anxiety among other emotional symptoms. Animal models indicate that repeated access to palatable foods such as sugar induces depression and anxiety-like behavior when the food is no longer available. However, the neurobiological mechanisms of how dietary restriction influences mood have not been fully understood. We used the two-bottle sucrose choice paradigm as an overeating and withdrawal model. Withdrawal after lengthy sucrose overeating elicited depression and anxiety-like behavior, which was reversed by sucrose reinstatement. In the nucleus accumbens (NAc) of sucrose withdrawal animals, dopamine levels and cAMP response element binding protein (CREB) activity were significantly reduced, while the inwardly rectifying K⁺ channel, Kir2.1, was significantly elevated. In addition, overexpression of Kir2.1 selectively in neurons expressing dopamine D1 receptors was sufficient to induce negative mood-linked behavior in the absence of sucrose overeating experience. As elevated K⁺ channels reduce neuronal excitability, a sucrose withdrawal-induced increase in Kir2.1 expression is able to decrease NAc activity, which provides a cellular basis for depression and anxiety-like behavior in animals.

Spatiotemporal control of porcine p65RHD expression by advanced Tet-On system in PIEC cells helps regulate NFкB activity

NFкB transcription activation leads to malfunction of endothelial cells, which is the main reason for pig xenograft rejection. Overexpression of a dominant negative mutant of porcine NFκB p65 (pp65RHD) could inhibit NFкB activation in endothelial cells. This study presents an advanced tetracycline-regulated system for pp65RHD spatiotemporal expression in porcine iliac endothelial cell line. In this system, an endothelial specific promoter ICAM-2 is used to improve pTet-On and internal ribosome entry site as well as enhanced green fluorescent protein (EGFP) elements are used to facilitate the result observation in pTRE-Tight. Through transfection and drug selection, we obtained 7 single cell clones containing the advanced Tet-On system, in which pp65RHD expression is under tight regulated by doxycycline and can be visualized easily through EGFP. The distribution of induced pp65RHD was verified by immunocytochemical assays test. Then, NFкB activity was tested. Luciferase reporter assays showed that NFкB activity in two clones was influenced by the Dox-induced pp65RHD expression, but other clones weren't influenced. Therefore, we picked up 2 cell clones from the uninfluenced clones for further investigation by immunocytochemical assays and RT-PCR detection. The final results supported the overexpression of pp65RHD in one clone could successfully inhibit NFкB activity. The success of pp65RHD spatiotemporal expression system is helpful to regulate NFкB activity and conquer cell-mediated immunity and could be used for preparation of transgenic pig, contributing to xenotransplantation.