The role of transforming growth factor-beta (TGF-beta) during ovarian follicular development in sheep

BACKGROUND: Recently, several members of the transforming growth factor-beta (TGF-beta) superfamily have been shown to be essential for regulating the growth and differentiation of ovarian follicles and thus fertility. METHODS: Ovaries of neonatal and adult sheep were examined for expression of the TGF-betas 1–3 and their receptors (RI and RII) by in situ hybridization using ovine cDNAs. The effects of TGF-beta 1 and 2 on proliferation and differentiation of ovine granulosa cells in vitro were also studied. RESULTS: The expression patterns of TGF-beta 1 and 2 were similar in that both mRNAs were first observed in thecal cells of type 3 (small pre-antral) follicles. Expression of both mRNAs continued to be observed in the theca of larger follicles and was also present in cells within the stroma and associated with the vascular system of the ovary. There was no evidence for expression in granulosa cells or oocytes. Expression of TGF-beta 3 mRNA was limited to cells associated with the vascular system within the ovary. TGFbetaRI mRNA was observed in oocytes from the type 1 (primordial) to type 5 (antral) stages of follicular growth and granulosa and thecal cells expressed this mRNA at the type 3 (small pre-antral) and subsequent stages of development. The TGFbetaRI signal was also observed in the ovarian stroma and vascular cells. In ovarian follicles, mRNA encoding TGFbetaRII was restricted to thecal cells of type 3 (small pre-antral) and larger follicles. In addition, expression was also observed in some cells of the surface epithelium and in some stromal cells. In granulosa cells cultured for 6 days, both TGF-beta 1 and 2 decreased, in a dose dependent manner, both the amount of DNA and concentration of progesterone. CONCLUSION: In summary, mRNA encoding both TGF-beta 1 and 2 were synthesized by ovarian theca, stroma and cells of the vascular system whereas TGF-beta 3 mRNA was synthesized by vascular cells. Luteinizing granulosa cells also responded to both TGF-beta 1 and beta 2 in vitro. These findings in sheep are consistent with TGF-beta potentially being an important autocrine regulator of thecal cell function and possibly a paracrine regulator of ovarian cell function at various development stages

The negotiation and co-construction of meaning and understanding within a postgraduate online learning community

There is an increasing development of courses and course components taught through teaching and learning dialogues online yet there is little secure knowledge regarding the educational quality and outcomes of these dialogues. Drawing on contemporary socio-cultural research, this paper adapts a well-established analytical framework (see Mercer, 1995) that has been developed to understand face to face educational dialogues to the new context of asynchronous electronic conferencing. The work reported is derived from an in-depth case study of a tutorial group of 11 students enrolled on a course within the Open University's MA in Open and Distance Learning. The course was taught on-line to an international cohort of students from wide-ranging academic backgrounds. The analyses of electronic conference archives presented here focus on understanding the students’ on-line collaborative work and the ways in which they constructed meaning, negotiated shared understanding and supported each other in the process of learning at a distance. The implications of the findings for educational practice are considered

UCT943, a next generation Plasmodium falciparum PI4K inhibitor preclinical candidate for the treatment of malaria

The 2-aminopyridine MMV048 was the first drug candidate inhibiting; Plasmodium; phosphatidylinositol 4-kinase (PI4K), a novel drug target for malaria, to enter clinical development. In an effort to identify the next generation of PI4K inhibitors, the series was optimized to improve properties such as solubility and antiplasmodial potency across the parasite life cycle, leading to the 2-aminopyrazine UCT943. The compound displayed higher asexual blood stage, transmission-blocking, and liver stage activities than MMV048 and was more potent against resistant; Plasmodium falciparum; and; Plasmodium vivax; clinical isolates. Excellent; in vitro; antiplasmodial activity translated into high efficacy in; Plasmodium berghei; and humanized; P. falciparum; NOD-; scid IL-2R; γ; null; mouse models. The high passive permeability and high aqueous solubility of UCT943, combined with low to moderate; in vivo; intrinsic clearance, resulted in sustained exposure and high bioavailability in preclinical species. In addition, the predicted human dose for a curative single administration using monkey and dog pharmacokinetics was low, ranging from 50 to 80 mg. As a next-generation; Plasmodium; PI4K inhibitor, UCT943, based on the combined preclinical data, has the potential to form part of a single-exposure radical cure and prophylaxis (SERCaP) to treat, prevent, and block the transmission of malaria

The Role of Oocyte Organelles in Determining Developmental Competence

The ability of an oocyte to undergo successful cytoplasmic and nuclear maturation, fertilization and embryo development is referred to as the oocyte’s quality or developmental competence. Quality is dependent on the accumulation of organelles, metabolites and maternal RNAs during the growth and maturation of the oocyte. Various models of good and poor oocyte quality have been used to understand the essential contributors to developmental success. This review covers the current knowledge of how oocyte organelle quantity, distribution and morphology differ between good and poor quality oocytes. The models of oocyte quality are also described and their usefulness for studying the intrinsic quality of an oocyte discussed. Understanding the key critical features of cytoplasmic organelles and metabolites driving oocyte quality will lead to methods for identifying high quality oocytes and improving oocyte competence, both in vitro and in vivo

The potential role of transforming growth factor beta family ligand interactions in prostate cancer

The transforming growth factor beta (TGF-β) family plays an important role in embryonic development and control of the cell cycle. Members of the TGF-β family have pleiotropic functions and are involved in both the inhibition and progression of various cancers. In particular, deregulation of the TGF-β family has been associated with prostate cancer, as both a mechanism of disease progression and a possible therapeutic target. This review concentrates on the TGF-βs, activins and inhibins, bone morphogenetic proteins and NODAL and their connection to prostate cancer. Whilst most studies examine the family members in isolation, there are multiple interactions that may occur between members which can alter their function. Such interactions include ligand competition for receptor binding and shared intracellular pathways such as the Mothers against decapentaplegic (SMAD) proteins. Another mechanism for interaction within the TGF-β family is facilitated by their dimeric structure; heterodimers can form which exhibit different functional capabilities to their homodimeric counterparts. The potential formation of TGF-β family heterodimers has not been well examined in prostate cancer. The multiple methods of interrelations between members highlights the need for gross analysis of the TGF-β family and related factors in association with prostate cancer, in order to discover possible future avenues for TGF-β based diagnosis and treatments of the disease. This review describes the role of the TGF-β family of proteins in cancer and, in particular, prostate cancer. After a brief overview, the role of individual members of the family is considered and how these members may be involved in prostate cancer growth is discussed. The review highlights the complex interactions that occur between family members and that may contribute to the progression of prostate cancer

Signalling pathways involved in the synergistic effects of human growth differentiation factor 9 and bone morphogenetic protein 15

Growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) act synergistically to regulate granulosa cell proliferation and steroid production in several species. Several non-Sma and mothers against decapentaplegic (SMAD) signalling pathways are involved in the action of murine and ovine GDF9 and BMP15 in combination, with the pathways utilised differing between the two species. The aims of this research were to determine if human GDF9 and BMP15 also act in a synergistic manner to stimulate granulosa cell proliferation and to identify which non-SMAD signalling pathways are activated. Human GDF9 with BMP15 (GDF9 + BMP15) stimulated an increase in 3H-thymidine incorporation (P < 0.001), which was greater than the increase with BMP15 alone, while GDF9 alone had no effect. The stimulation of 3H-thymidine incorporation by GDF9 + BMP15 was reduced by the addition of inhibitors to the SMAD2/3, nuclear factor-KB (NF-KB) and c-Jun N-terminal kinase (JNK) signalling pathways. Inhibitors to the SMAD1/5/8, extracellular signal-regulated kinase mitogen-activated protein kinase (ERK-MAPK) or p38-MAPK pathways had no effect. The addition of the BMP receptor 2 (BMPR2) extracellular domain also inhibited stimulation of 3H-thymidine incorporation by GDF9 + BMP15. In conclusion, human GDF9 and BMP15 act synergistically to stimulate granulosa cell proliferation, a response that also involves species-specific non-SMAD signalling pathways

Bone morphogenetic protein 15 and growth differentiation factor 9 co-operate to regulate granulosa cell function

The oocyte-secreted polypeptide growth factors, growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15, also known as GDF9B) have both been shown to be essential for ovarian follicular growth and function. The effects of murine (m) and ovine (o) GDF9 as well as oBMP15, alone or together, on 3H-thymidine uptake and progesterone and inhibin production by granulosa cells from rats were determined. Murine GDF9 stimulated thymidine incorporation by granulosa cells whereas oGDF9 and oBMP15 alone had no effect. However, oBMP15 given together with mGDF9 or oGDF9 was very potent in stimulating 3H-thymidine incorporation by granulosa cells with a greater than 3-fold stimulation compared with any growth factor alone. The synergistic effect of oBMP15 and oGDF9 was almost completely blocked by antibodies generated against these growth factors when administered either alone or in combination. While neither GDF9 (murine or ovine) nor oBMP15 were able to modulate FSH-stimulated progesterone production on their own, FSH-stimulated progesterone production by granulosa cells was potently inhibited when BMP15 and GDF9 were administered together. Immunoreactive -inhibin levels increased more than 15-fold from granulosa cells when BMP15 and GDF9 were given together whereas consistent stimulatory effects of either growth factor alone were not observed. The effects of GDF9 and BMP15, when added together, were different than those observed for the growth factors alone. Therefore, we hypothesize that within the ovary, these oocyte-secreted growth factors co-operate to regulate proliferation and gonadotropin-induced differentiation of granulosa cells in mammals.Kenneth P McNatty, Jennifer L Juengel, Karen L Reader, Stan Lun, Samu Myllymaa, Steve B Lawrence, Andrea Western, Mohamed F Meerasahib, David G Mottershead, Nigel P Groome, Olli Ritvos and Mika P E Laitine