Mouse 24p3 protein has an effect on L929 cell viability

It is well known that mouse uterine 24p3 protein, is an acute phase protein, secreted from the L929 cell line, and that it will be induced by the dexamethasone stimulation of the cell. We investigated the possible effects of 24p3 protein on the L929 cell line, by observing its morphological change, ROS increase and viability decrease, by the process of culturing in a 24p3 protein-supplemented medium. Following the L929 cells' exposure to the 24p3 protein supplement for a period of 72 hours, S-phase cells accumulated to a significant degree, suggesting that the entry into the G2/M phase from the S phase, in the cell cycle progression, was blocked. There was a significant decrease in cell numbers and increased DNA damage within the cells in the presence of 24p3 protein within the medium for 96 hours, implying that they have undergone pathway of cell death. After 96h incubation in low concentration of 24p3 protein, the result of PI/annexin V double staining showed cell death obviously. These results suggest that 24p3 protein-induced S phase arrest in the cell cycle, would cause DNA damage, followed by cell death in the L929 cells.     

Retinoic acid has an antiestrogenic effect on different regulated estrogen genes in different cellular types]

In this paper, we confirmed that retinoic acid is an antiestrogenic compound with respect to different chimaeric estrogenic responses and with respect to different cellular types. This was shown by transient transfection of MCF-7 cells with plasmids driving the chloramphenicol acetyl-transferase gene via different estrogenic regulatory part (pS2) and the first promotor of the progesterone receptor gene (PR1); an identical conclusion was obtained in HeLa cells by cotransfecting a plasmid expressing the estrogen receptor. In addition, the inhibitory effect of retinoic acid was not observed for genes regulated by the progesterone receptor and the glucocorticoid receptor. As the antiestrogenic effect of retinoic acid was increased by cotransfecting acid receptor(s) RAR alpha, beta, gamma, we concluded that RAR(s) is(are) involved in the antiestrogenic effect of retinoic acid.     

Thermal manipulation during the middle incubation stage has a repressive effect on the immune organ development of Peking ducklings

Avian embryos are easily influenced by their environment during incubation. Previous studies have demonstrated that incubation temperature changes could influence muscle development and body weight, which subsequently determine the adult phenotype. The objective of this study was to investigate whether the development of immune organs in ducklings could be influenced by thermal manipulation during the middle stage of incubation. To evaluate this hypothesis, a control group was incubated under a normal temperature from E11 to E24, while the incubation temperature of the experimental group was increased by 1 °C. Our results indicated that slight changes in the incubation temperature significantly repressed the bursa of Fabricius index of the duck embryo on E25 (F1, 58=122.51, P<0.0001) and significantly repressed the spleen index of neonatal ducklings (F1, 58=74.38, P<0.0001). At 0 day posthatching (dph) and 14 dph, ducklings hatched from eggs incubated under the higher temperature had a lower percentage of globulin than the control group (F1, 10=19.97, P=0.0111; F1, 10=9.8, P=0.0352). The IFN-γ concentration of ducklings at 14 dph displayed the same trend (F1, 10=284.49, P<0.0001). These results suggested that thermal manipulation during the middle stage of incubation had a repressive effect on the development of immune organs and reduced the concentrations of serum globulin and IFN-γ. These results demonstrated that the subtle alteration of incubation temperature may weaken ducklings' immunity.     

New hepatitis B virus of cranes that has an unexpected broad host range

All hepadnaviruses known so far have a very limited host range, restricted to their natural hosts and a few closely related species. This is thought to be due mainly to sequence divergence in the large envelope protein and species-specific differences in host components essential for virus propagation. Here we report an infection of cranes with a novel hepadnavirus, designated CHBV, that has an unexpectedly broad host range and is only distantly evolutionarily related to avihepadnaviruses of related hosts. Direct DNA sequencing of amplified CHBV DNA as well a sequencing of cloned viral genomes revealed that CHBV is most closely related to, although distinct from, Ross' goose hepatitis B virus (RGHBV) and slightly less closely related to duck hepatitis B virus (DHBV). Phylogenetically, cranes are very distant from geese and ducks and are most closely related to herons and storks. Naturally occurring hepadnaviruses in the last two species are highly divergent in sequence from RGHBV and DHBV and do not infect ducks or do so only marginally. In contrast, CHBV from crane sera and recombinant CHBV produced from LMH cells infected primary duck hepatocytes almost as efficiently as DHBV did. This is the first report of a rather broad host range of an avihepadnavirus. Our data imply either usage of similar or identical entry pathways and receptors by DHBV and CHBV, unusual host and virus adaptation mechanisms, or divergent evolution of the host genomes and cellular components required for virus propagation.     

Licochalcone E has an antidiabetic effect

Licochalcone E (lico E) is a retrochalcone isolated from the root of Glycyrrhiza inflata. Retrochalcone compounds evidence a variety of pharmacological profiles, including anticancer, antiparasitic, antibacterial, antioxidative and superoxide-scavenging properties. In this study, we evaluated the biological effects of lico E on adipocyte differentiation in vitro and obesity-related diabetes in vivo. We employed 3T3-L1 preadipocyte and C3H10T1/2 stem cells for in vitro adipocyte differentiation study and diet-induced diabetic mice for in vivo study. The presence of lico E during adipogenesis induced adipocyte differentiation to a significant degree, particularly at the early induction stage. Licochalcone E evidenced weak, but significant, peroxisome proliferator-activated receptor gamma (PPARγ) ligand-binding activity. Two weeks of lico E treatment lowered blood glucose levels and serum triglyceride levels in the diabetic mice. Additionally, treatment with lico E resulted in marked reductions in adipocyte size and increases in the mRNA expression levels of PPARγ in white adipose tissue (WAT). Licochalcone E was also shown to significantly stimulate Akt signaling in epididymal WAT. In conclusion, lico E increases the levels of PPARγ expression, at least in part, via the stimulation of Akt signals and functions as a PPARγ partial agonist, and this increased PPARγ expression enhances adipocyte differentiation and increases the population of small adipocytes, resulting in improvements in hyperglycemia and hyperlipidemia under diabetic conditions.     

Regulation of specific genes during the cell cycle

Evidence for differential gene expresion during the cell cycle and approaches for studying cell-cycle-stage specific gene expression are summarized. Attention is focused on regulation of histone gene expression during the cell cycle of continuously dividing cells and after stimulation of nondividing cells to proliferate. The level(s) at which control of histone gene expression occurs and the possible involvement of chromosomal proteins in the regulation of histone gene expression are discussed. The preparation of cloned human histone sequences and their use in studying the structural and functional properties of human histone genes are presented.     

Altered differentiation and clustering of Sertoli cells in transgenic mice showing a Sertoli cell specific knockout of the connexin 43 gene

Histological analysis revealed that Sertoli cell specific knockout of the predominant testicular gap junction protein connexin 43 results in a spermatogenic arrest at the level of spermatogonia or Sertoli cell-only syndrome, intratubular cell clusters and still proliferating adult Sertoli cells, implying an important role for connexin 43 in the Sertoli and germ cell development. This study aimed to determine the (1) Sertoli cell maturation state, (2) time of occurrence and (3) composition, differentiation and fate of clustered cells in knockout mice. Using immunohistochemistry connexin 43 deficient Sertoli cells showed an accurate start of the mature markers androgen receptor and GATA-1 during puberty and a vimentin expression from neonatal to adult. Expression of anti-Muellerian hormone, as a marker of Sertoli cell immaturity, was finally down-regulated during puberty, but its disappearance was delayed. This observed extended anti-Müllerian hormone synthesis during puberty was confirmed by western blot and Real-Time PCR and suggests a partial alteration in the Sertoli cell differentiation program. Additionally, Sertoli cells of adult knockouts showed a permanent and uniform expression of GATA-1 at protein and mRNA level, maybe caused by the lack of maturing germ cells and missing negative feedback signals. At ultrastructural level, basally located adult Sertoli cells obtained their mature appearance, demonstrated by the tripartite nucleolus as a typical feature of differentiated Sertoli cells. Intratubular clustered cells were mainly formed by abnormal Sertoli cells and single attached apoptotic germ cells, verified by immunohistochemistry, TUNEL staining and transmission electron microscopy. Clusters first appeared during puberty and became more numerous in adulthood with increasing cell numbers per cluster suggesting an age-related process. In conclusion, adult connexin 43 deficient Sertoli cells seem to proliferate while maintaining expression of mature markers and their adult morphology, indicating a unique and abnormal intermediate phenotype with characteristics common to both undifferentiated and differentiated Sertoli cells.     

Prenylation has a compound specific effect on the estrogenicity of naringenin and genistein

A variety of plant derived substances, so-called phytoestrogens (PEs), although structurally not related to steroids, produce effects similar to the mammalian estradiol. However, little is known so far about the structural requirements which determine PE activities. Taking into consideration that prenylation reactions are relatively common in plant secondary metabolism, the activity of a set of three PE derivatives of genistein and naringenin, namely genistein, 8-prenylgenistein (8PG), 6-(1,1-dimethylallyl)genistein (6DMAG), naringenin, 8-prenylnaringenin (8PN) and 6-(1,1-dimethylallyl)naringenin (6DMAN) was compared regarding structure–estrogenicity relationships in three functionally different estrogen receptor assays.Strong estrogenic activities were recorded for 6DMAN and 8PN in all assays used, while the parent compound naringenin showed only very weak estrogenicity.In contrast, in the case of genistein derivatives, only genistein itself exhibited estrogenic activity in a yeast based assay. In MVLN breast cancer cells, a bioluminescent MCF-7-derived cell line, the estrogenic activity of all three genistein derivatives was similar. Studying alkaline phosphatase activity in Ishikawa endometrial cancer cells as an estrogenic response marker revealed a similar pattern of estrogenicity of the genistein derivatives compared to the yeast based assay although a slight estrogenic effect of 6DMAG and 8PG was apparent.In summary, this study demonstrates that prenylation often found in plant secondary metabolism differentially modifies estrogenic properties of PEs depending on the basic structure of the respective PE.     

Quorum sensing has an unexpected role in virulence in the model pathogen Citrobacter rodentium

The bacterial mouse pathogen Citrobacter rodentium causes attaching and effacing (AE) lesions in the same manner as pathogenic Escherichia coli, and is an important model for this mode of pathogenesis. Quorum sensing (QS) involves chemical signalling by bacteria to regulate gene expression in response to cell density. E. coli has never been reported to have N-acylhomoserine lactone (AHL) QS, but it does utilize luxS-dependent signalling. We found production of AHL QS signalling molecules by an AE pathogen, C. rodentium. AHL QS is directed by the croIR locus and a croI mutant is affected in its surface attachment, although not in Type III secretion. AHL QS has an important role in virulence in the mouse as, unexpectedly, the QS mutant is hypervirulent; by contrast, we detected no impact of luxS inactivation. Further study of QS in Citrobacter should provide new insights into AE pathogenesis. As the croIR locus might have been horizontally acquired, AHL QS might exist in some strains of pathogenic E. coli.     

Short-term stimulatory effect of Sertoli cell conditioned medium on Leydig cell steroidogenesis is not mediated by inhibin

Addition of concentrated rat Sertoli cell conditioned medium (rSCCM) to isolated Leydig cells from immature rats stimulated steroid production more than 13-fold within 4 h. LH-stimulated steroidogenesis was not enhanced by addition of rSCCM. The biological activity of the concentrated rSCCM was higher after incubation of Sertoli cells with FSH, whereas FSH alone did not stimulate steroid production. This effect of rSCCM was not due to inhibin, since highly purified 32 kDa rat inhibin, in doses equivalent to those present in rSCCM, had no effect on steroidogenesis during the 4 h incubation period. Furthermore, inhibin could be separated from the Leydig cell stimulating factor by anion-exchange chromatography. These results indicate a short-term paracrine control of Leydig cell steroidogenesis by Sertoli cell derived factors, which differ from inhibin.     

Experimental ectoparasite removal has a sex‐specific effect on nestling telomere length

Parasites are a strong selective force that can influence fitness‐related traits. The length of chromosome‐capping telomeres can be used to assess the long‐term costs of parasitism, as telomere loss accelerates in response to environmental stressors and often precedes poorer survival prospects. Here, we explored the sex‐specific effects of ectoparasite removal on morphology and telomere length in nestling tree swallows (Tachycineta bicolor). To do so, we experimentally removed blow fly (Protocalliphora spp.) larvae from nests using Permethrin, a broad‐spectrum insecticide. Compared to water‐treated controls, insecticide treatment of nests had a sex‐biased effect on blood telomere length: ectoparasite removal resulted in significantly longer telomeres in males but not females. While this treatment did not influence nestling body mass, it was associated with reduced feather development regardless of sex. This may reflect a relaxed pressure to fledge quickly in the absence of parasites, or alternatively, could be a negative side effect of permethrin on morphology. Exploring robust sex‐specific telomere dynamics in response to early‐life environmental pressures such as parasitism will shed light on sexual dimorphism in adult life histories and aging.     

An unexpected effect of capsaicin on spontaneous GABA-ergic IPSCS in hippocampal cell cultures

Vanilloid receptors 1 (VRs1) expressed in a subpopulation of sensory neurons and responsible for processing of chemical and thermal noxious stimuli were also shown to be expressed in several cerebral structures and to be involved in the regulation of glutamatergic synaptic transmission. In this study, we started to investigate the possibility that VRs1 are also involved in the regulation of GABA-ergic synaptic transmission. For this purpose, the effect of a VR1 agonist, capsaicin, on spontaneous GABA-ergic inhibitory postsynaptic currents (IPSCs) was studied in hippocampal cell cultures using a patch-clamp technique. It was found that capsaicin (10 μM) decreased both the frequency and amplitude of spontaneous IPSCs. This finding suggests the involvement of VRs1 in the regulation of neuronal firing in some GABA-ergic interneurons and in the modulation of the efficacy of GABA-ergic synaptic transmission. However, considering the direction of the effect (a decrease in the IPSC frequency) and lack of its desensitization, the involvement of other receptor(s) also cannot currently be ruled out. Neirofiziologiya/Neurophysiology, Vol. 38, No. 4, pp. 364–367, July–August, 2006.     

Cortactin has an essential and specific role in osteoclast actin assembly

Osteoclasts are essential for bone dynamics and calcium homeostasis. The cells form a tight seal on the bone surface, onto which they secrete acid and proteases to resorb bone. The seal is associated with a ring of actin filaments. Cortactin, a c-Src substrate known to promote Arp2/3-mediated actin assembly in vitro, is expressed in osteoclasts and localizes to the sealing ring. To address the role of cortactin and actin assembly in osteoclasts, we depleted cortactin by RNA interference. Cortactin-depleted osteoclasts displayed a complete loss of bone resorption with no formation of sealing zones. On nonosteoid surfaces, osteoclasts flatten with a dynamic, actin-rich peripheral edge that contains podosomes, filopodia, and lamellipodia. Cortactin depletion led to a specific loss of podosomes, revealing a tight spatial compartmentalization of actin assembly. Podosome formation was restored in cortactin-depleted cells by expression of wild-type cortactin or a Src homology 3 point mutant of cortactin. In contrast, expression of a cortactin mutant lacking tyrosine residues phosphorylated by Src did not restore podosome formation. Cortactin was found to be an early component of the nascent podosome belt, along with dynamin, supporting a role for cortactin in actin assembly.     

Decorin has an appetite for endothelial cell autophagy

DCN (decorin), an extracellular matrix constituent and archetypical small leucine-rich proteoglycan (SLRP), acts as a soluble tumor repressor. DCN exerts high-affinity binding interactions with receptor tyrosine kinases and evokes receptor internalization consequent with lysosomal degradation for tumorigenic and angiogenic suppression. In our recent study, we discovered that DCN evokes synthesis of PEG3 (paternally expressed 3), an imprinted gene often silenced in various forms of cancer. Upon DCN stimulation, PEG3 relocalizes to BECN1- and LC3-positive phagophores. Importantly, PEG3 physically associates with BECN1- and LC3-containing supramolecular complexes, in a DCN-inducible manner, and PEG3 is necessary to maintain homeostatic levels of BECN1. Furthermore, DCN evokes a protracted autophagic program via transactivation of the BECN1 and MAPLC3A loci that is critically dependent on PEG3 expression. Mechanistically, DCN directly binds to the Ig domains 3–5 of the KDR/VEGFR2 ectodomain, in a region that partially overlaps with the canonical binding site for VEGFA. Therefore, we have unveiled a novel mechanism for a secreted proteoglycan to induce endothelial cell autophagy in a PEG3-dependent manner. These findings are consistent with earlier preclinical studies focusing on DCN-mediated tumorigenic and angiogenic suppression and may represent the mechanism of action to achieve these effects. Therefore, DCN and perhaps other members of this class of matrix constituents may represent a novel control of autophagy from the outside of the cells.     

Sertoli cell transplants: their use in the treatment of neurodegenerative disease

The efficacy of treating neurodegenerative diseases with the transplantation of fetal tissue has been demonstrated in animal models of Parkinson's disease, Huntington's disease and stroke. In the clinical setting, neural transplantation as a treatment for patients with Parkinson's disease has shown promising results. However, for this treatment method to be effective neuronal survival needs to be improved through either trophic support or localized immunoprotection. Co-transplanting Sertoli cells, which express many nutritive, regulatory, trophic and immunosuppressive factors, with fetal neural cells could provide both of these requirements. Such a strategy could enhance the recovery benefits associated with transplantation and decrease the need for, and the risks associated with, long-term systemic immunosuppression.