Tube-like structures within the ovarian follicle of Hydrolagus colliei indicate the early origins of follicle cell processes.

Follicle cell processes (FCP) are actin-based, tube-like structures that connect the developing oocyte to the follicle cells throughout oogenesis. They were first described in Selachians (sharks) where their suggested roles were facilitating the transport of metabolites to the developing oocyte and providing structural support to the large egg cells of sharks, an early stage in the evolution of viviparity. Subsequent studies found that FCP are absent in Rajiformes (skates), suggesting that FCP may have been novel structures specific to the sharks. Here, FCP in Hydrolagus colliei, a Chimaeriform, were described. The FCP of H. colliei differ morphologically from those previously described in sharks, but as they also contain actin, they presumably play similar roles provisioning the developing oocyte and providing structural support. The presence of FCP in the order Chimaeriformes suggests that their origin predates the split of the elasmobranchs and the holocephalans.

Glyceollin I Reverses Epithelial to Mesenchymal Transition in Letrozole Resistant Breast Cancer through ZEB1.

Although aromatase inhibitors are standard endocrine therapy for postmenopausal women with early-stage metastatic estrogen-dependent breast cancer, they are limited by the development of drug resistance. A better understanding of this process is critical towards designing novel strategies for disease management. Previously, we demonstrated a global proteomic signature of letrozole-resistance associated with hormone-independence, enhanced cell motility and implications of epithelial mesenchymal transition (EMT). Letrozole-resistant breast cancer cells (LTLT-Ca) were treated with a novel phytoalexin, glyceollin I, and exhibited morphological characteristics synonymous with an epithelial phenotype and decreased proliferation. Letrozole-resistance increased Zinc Finger E-Box Binding Homeobox 1 (ZEB1) expression (4.51-fold), while glyceollin I treatment caused a -3.39-fold reduction. Immunofluorescence analyses resulted of glyceollin I-induced increase and decrease in E-cadherin and ZEB1, respectively. In vivo studies performed in ovariectomized, female nude mice indicated that glyceollin treated tumors stained weakly for ZEB1 and N-cadherin and strongly for E-cadherin. Compared to letrozole-sensitive cells, LTLT-Ca cells displayed enhanced motility, however in the presence of glyceollin I, exhibited a 68% and 83% decrease in invasion and migration, respectively. These effects of glyceollin I were mediated in part by inhibition of ZEB1, thus indicating therapeutic potential of glyceollin I in targeting EMT in letrozole resistant breast cancer.

The Wnt signaling mediator tcf1 is required for expression of foxd3 during Xenopus gastrulation.

TCF1 belongs to the family of LEF1/TCF transcription factors that regulate gene expression downstream of Wnt/ß-catenin signaling, which is crucial for embryonic development and is involved in adult stem cell regulation and tumor growth. In early Xenopus embryos, tcf1 plays an important role in mesoderm induction and patterning. Foxd3 emerged as a potential tcf1 target gene in a microarray analysis of gastrula stage embryos. Because foxd3 and tcf1 are coexpressed during gastrulation, we investigated whether foxd3 is regulated by tcf1. By using morpholino-mediated knockdown, we show that during gastrulation foxd3 expression is dependent on tcf1. By chromatin immunoprecipitation, we also demonstrate direct interaction of ß-catenin/tcf complexes with the foxd3 gene locus. Hence, our results indicate that tcf1 acts as an essential activator of foxd3, which is critical for dorsal mesoderm formation in early embryos.

High-glucose-induced endothelial cell injury is inhibited by a Peptide derived from human apolipoprotein E.

Although the importance of human apolipoprotein E (apoE) in vascular diseases has clearly been established, most of the research on apoE has focused on its role in cholesterol metabolism. In view of the observation that apoE and its functional domains impact extracellular matrix (ECM) remodeling, we hypothesized that apoE could also confer protection against ECM degradation by mechanisms independent of its role in cholesterol and lipoprotein transport. The ECM degrading enzyme, heparanase, is secreted by cells as pro-heparanase that is internalized through low-density lipoprotein (LDL) receptor-related protein-1 (LRP-1) to become enzymatically active. Both apoE and pro-heparanase bind the LRP-1. We further hypothesized that an apoE mimetic peptide (apoEdp) would inhibit the production of active heparanase by blocking LRP-1-mediated uptake of pro-heparanase and thereby decrease degradation of the ECM. To test this hypothesis, we induced the expression of heparanase by incubating human retinal endothelial cells (hRECs) with high glucose (30 mM) for 72 hours. We found that elevated expression of heparanase by high glucose was associated with increased shedding of heparan sulfate (ΔHS) and the tight junction protein occludin. Treatment of hRECs with 100 µM apoEdp in the presence of high glucose significantly reduced the expression of heparanase, shedding of ΔHS, and loss of occludin as detected by Western blot analysis. Either eye drop treatment of 1% apoEdp topically 4 times a day for 14 consecutive days or intraperitoneal injection (40 mg/kg) of apoEdp daily for 14 consecutive days in an in vivo mouse model of streptozotocin-induced diabetes inhibited the loss of tight junction proteins occludin and zona occludin- 1 (ZO-1). These findings imply a functional relationship between apoE and endothelial cell matrix because the deregulation of these molecules can be inhibited by a short peptide derived from the receptor-binding region of apoE. Thus, strategies targeting ECM-degrading enzymes could be therapeutically beneficial for treating diabetic retinopathy.

A novel set of structures within the elasmobranch, ovarian follicle.

Elasmobranch fishes produce some of the largest oocytes known, exceeding 10 cm in diameter. Using various microscopy techniques we investigated the structural adaptations which facilitate the production of these large egg cells in three species of shark: the Atlantic sharpnose shark, Rhizoprionodon terraenovae, dusky smoothound, Mustelus canis and the little gulper shark, Centrophorus uyato. The ovarian follicle of elasmobranchs follows the typical vertebrate pattern, with one notable exception; the zona pellucida reaches extreme widths, over 70 µm, during early oogenesis. Contact between the follicle cells and the oocyte across the zona pellucida is necessary for oogenesis. We describe here a novel set of large, tube-like structures, which we named follicle cell processes that bridge this gap. The follicle cell processes are more robust than the microvilli associated with the follicle cells and the oocyte plasma membrane and much longer. During early oogenesis the follicle increases in size relatively quickly resulting in a wide zona pellucida. At this stage the follicle cell processes appear taut, uniform and radially oriented. As oogenesis continues the zona pellucida narrows and the follicle cell processes change their orientation, appearing to wrap around the oocyte. The presence of the contractile protein actin within the follicle cell processes and their change in orientation may well be an adaptation for maintaining the integrity of these large oocytes. The follicle cell processes also contain electron dense material, identical to material found within the follicle cells, suggesting a role in the transport of metabolites to the developing oocyte.

Wnt6 expression in epidermis and epithelial tissues during Xenopus organogenesis.

Here, we report the localization within embryonic tissues of xWnt6 protein; together with the temporal and spatial expression of Xenopus laevis Wnt6 mRNA. Wnt6 expression in Xenopus embryos is low until later stages of neurulation, when it is predominantly found in the surface ectoderm. Wnt6 expression increases during early organogenesis in the epidermis overlaying several developing organs, including the eye, heart, and pronephros. At later stages of development, Wnt6 mRNA and protein generally localize in epithelial tissues and specifically within the epithelial tissues of these developing organs. Wnt6 localization correlates closely with sites of both epithelial to mesenchymal transformations and mesenchymal to epithelial transformations. Xenopus Wnt6 sequence and its expression pattern are highly conserved with other vertebrates. Xenopus embryos, therefore, provide an excellent model system for investigating the function of vertebrate Wnt6 in organ development and regulation of tissue architecture.