| 1. |
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| 2. |
- Dubbaka Venu, Pradeep Reddy, 1982-
(författare)
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Molecular studies of intra-oocyte phosphatidylinositol 3 kinase (PI3K) signaling pathway in controlling female fertility
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The primordial follicle pool is the main source of developing follicles in the ovary. The length of reproductive life and the onset of menopause are governed by the amount of primordial follicles in the ovary. The genetic factors and molecular mechanisms that maintain the primordial follicles in a dormant and surviving state for the whole of reproductive life are not well understood. The phosphatidylinositol 3 kinase (PI3K) signaling pathways in the oocyte that control oocyte growth and early follicular development are largely unknown. The major aim of this thesis was to investigate the functional role of the intra-oocyte PI3K pathway in the regulation of primordial follicle activation and survival. Phosphatase and tensin homolog deleted on chromosome ten (PTEN) is a major negative regulator of PI3K. The conditional deletion of Pten in the oocytes of primordial follicles led to the overgrowth of oocytes and activation of the entire pool of primordial follicles. There were higher numbers of activated primordial follicles at postnatal day 8 (PD8) in ovaries lacking PTEN in oocytes; by PD35 all the primordial follicles were activated and all the follicles were depleted by 12 weeks, causing premature ovarian failure (POF). In addition, the rate of follicular death that occurs during sexual maturity is reduced in ovaries that lack PTEN in oocytes. Further mechanistic studies revealed that loss of Pten in oocytes resulted in elevated Akt signaling and upregulation of both expression and activation of ribosomal protein S6 (rpS6). The overactivation of primordial follicles in ovaries that lack PTEN in oocytes is believed to be due to elevated expression and activation of rpS6. PTEN in oocytes is indispensable for the maintenance of primordial follicles in dormancy. To study the role of the intra-oocyte PI3K signaling pathway in controlling the survival and maintenance of primordial follicles, 3-phosphoinositide-dependent protein kinase-1 (PDK1) was deleted in oocytes of primordial follicle. The loss of Pdk1 in oocytes led to the depletion of most primordial follicles around the onset of sexual maturity, causing POF during early adulthood. Furthermore, the activation of Akt, p70 S6 kinase 1 (S6K1), and rpS6 was impaired in oocytes that lacked PDK1. The suppressed PDK1–Akt–S6K1–rpS6 signaling in oocytes appears to be responsible for the loss of primordial follicles. The excessive activation of primordial follicles seen in the absence of Pten in oocytes could be reversed by concurrent deletion of Pdk1. In addition, the elevated activation of Akt and S6K1 in the absence of PTEN in oocytes was not observed in PTEN and PDK1 double mutant mice. Similarly, the hyperphosphorylation of rpS6 in oocytes that lack PTEN was prevented in double mutant mice, which was most likely due to downregulation of S6K1 activation. Thus, inactivation of rpS6 in double mutant mice might be the reason for the prevention of excessive primordial follicular activation and survival. PTEN and PDK1 in oocytes are essential for the maintenance of quiescence and survival of primordial follicles. The molecular network involving PI3K/PTEN–PDK1 signaling in oocyte controls the survival, loss, and activation of primordial follicles, which together govern reproductive aging and determine the length of reproductive life in females. The results of the above studies indicate that the mammalian oocyte serves as the seat of programming of follicular activation and survival.
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| 3. |
- Dubbaka Venu, Pradeep Reddy, 1982-, et al.
(författare)
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Oocyte-specific deletion of Pten causes premature activation of the primordial follicle pool
- 2008
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 319:5863, s. 611-613
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Tidskriftsartikel (refereegranskat)abstract
- In the mammalian ovary, progressive activation of primordial follicles from the dormant pool serves as the source of fertilizable ova. Menopause, or the end of female reproductive life, occurs when the primordial follicle pool is exhausted. However, the molecular mechanisms underlying follicle activation are poorly understood. We provide genetic evidence that in mice lacking PTEN (phosphatase and tensin homolog deleted on chromosome 10) in oocytes, a major negative regulator of phosphatidylinositol 3-kinase (PI3K), the entire primordial follicle pool becomes activated. Subsequently, all primordial follicles become depleted in early adulthood, causing premature ovarian failure (POF). Our results show that the mammalian oocyte serves as the headquarters of programming of follicle activation and that the oocyte PTEN-PI3K pathway governs follicle activation through control of initiation of oocyte growth.
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| 4. |
- Dubbaka Venu, Pradeep Reddy, 1982-, et al.
(författare)
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PDK1 signaling in oocytes controls reproductive aging and lifespan by manipulating the survival of primordial follicles
- 2009
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 18:15, s. 2813-2824
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Tidskriftsartikel (refereegranskat)abstract
- The molecular mechanisms that control reproductive aging and menopausal age in females are poorly understood. Here, we provide genetic evidence that 3-phosphoinositide-dependent protein kinase-1 (PDK1) signaling in oocytes preserves reproductive lifespan by maintaining the survival of ovarian primordial follicles. In mice lacking the PDK1-encoding gene Pdk1 in oocytes, the majority of primordial follicles are depleted around the onset of sexual maturity, causing premature ovarian failure (POF) during early adulthood. We further showed that suppressed PDK1-Akt-p70 S6 kinase 1 (S6K1)-ribosomal protein S6 (rpS6) signaling in oocytes appears to be responsible for the loss of primordial follicles, and mice lacking the Rps6 gene in oocytes show POF similar to that in Pdk1-deficient mice. In combination with our earlier finding that phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in oocytes suppresses follicular activation, we have now pinpointed the molecular network involving phosphatidylinositol 3 kinase (PI3K)/PTEN-PDK1 signaling in oocytes that controls the survival, loss and activation of primordial follicles, which together determine reproductive aging and the length of reproductive life in females. Underactivation or overactivation of this signaling pathway in oocytes is shown to cause pathological conditions in the ovary, including POF and infertility.
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| 5. |
- Gorgolewski, Krzysztof J., et al.
(författare)
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BIDS apps: Improving ease of use, accessibility, and reproducibility of neuroimaging data analysis methods
- 2017
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Ingår i: PloS Computational Biology. - : Public Library of Science (PLoS). - 1553-734X .- 1553-7358. ; 13:3
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Tidskriftsartikel (refereegranskat)abstract
- The rate of progress in human neurosciences is limited by the inability to easily apply a wide range of analysis methods to the plethora of different datasets acquired in labs around the world. In this work, we introduce a framework for creating, testing, versioning and archiving portable applications for analyzing neuroimaging data organized and described in compliance with the Brain Imaging Data Structure (BIDS). The portability of these applications (BIDS Apps) is achieved by using container technologies that encapsulate all binary and other dependencies in one convenient package. BIDS Apps run on all three major operating systems with no need for complex setup and configuration and thanks to the comprehensiveness of the BIDS standard they require little manual user input. Previous containerized data processing solutions were limited to single user environments and not compatible with most multi-tenant High Performance Computing systems. BIDS Apps overcome this limitation by taking advantage of the Singularity container technology. As a proof of concept, this work is accompanied by 22 ready to use BIDS Apps, packaging a diverse set of commonly used neuroimaging algorithms.
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| 6. |
- Jagarlamudi, Krishna, et al.
(författare)
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Genetically modified mouse models for premature ovarian failure (POF)
- 2010
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Ingår i: Molecular and Cellular Endocrinology. - : Elsevier BV. - 0303-7207 .- 1872-8057. ; 315:1-2, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Premature ovarian failure (POF) is a complex disorder that affects approximately 1% of women. POF is characterized by the depletion of functional ovarian follicles before the age of 40 years, and clinically, patients may present with primary amenorrhea or secondary amenorrhea. Although some genes have been hypothesized to be candidates responsible for POF, the etiology of most of the cases is idiopathic, with the underlying causes still unidentified because of the heterogeneity of the disease. In this review, we consider some mutant mouse models that exhibit phenotypes which are comparable to human POF, and we suggest that the use of these mouse models may help us to gain a better understanding of the molecular mechanisms underlying POF in humans.
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| 7. |
- Jagarlamudi, Krishna, 1980-, et al.
(författare)
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Oocyte-specific deletion of Pten in mice reveals a stage-specific function of PTEN/PI3K signaling in oocytes in controlling follicular activation
- 2009
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 4:7, s. e6186-
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Tidskriftsartikel (refereegranskat)abstract
- Immature ovarian primordial follicles are essential for maintenance of the reproductive lifespan of female mammals. Recently, it was found that overactivation of the phosphatidylinositol 3-kinase (PI3K) signaling in oocytes of primordial follicles by an oocyte-specific deletion of Pten (phosphatase and tensin homolog deleted on chromosome ten), the gene encoding PI3K negative regulator PTEN, results in premature activation of the entire pool of primordial follicles, indicating that activation of the PI3K pathway in oocytes is important for control of follicular activation. To investigate whether PI3K signaling in oocytes of primary and further developed follicles also plays a role at later stages in follicular development and ovulation, we conditionally deleted the Pten gene from oocytes of primary and further developed follicles by using transgenic mice expressing zona pellucida 3 (Zp3) promoter-mediated Cre recombinase. Our results show that Pten was efficiently deleted from oocytes of primary and further developed follicles, as indicated by the elevated phosphorylation of the major PI3K downstream component Akt. However, follicular development was not altered and oocyte maturation was also normal, which led to normal fertility with unaltered litter size in the mutant mice. Our data indicate that properly controlled PTEN/PI3K-Akt signaling in oocytes is essential for control of the development of primordial follicles whereas overactivation of PI3K signaling in oocytes does not appear to affect the development of growing follicles. This suggests that there is a stage-specific function of PTEN/PI3K signaling in mouse oocytes that controls follicular activation.
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| 8. |
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| 9. |
- Liu, Lian, et al.
(författare)
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Infertility caused by retardation of follicular development in mice with oocyte-specific expression of Foxo3a
- 2007
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Ingår i: Development. - : The Company of Biologists. - 0950-1991 .- 1477-9129. ; 134:1, s. 199-209
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, mammalian oocytes have been proposed to have important roles in the orchestration of ovarian follicular development and fertility. To determine whether intra-oocyte Foxo3a, a component of the phosphatidylinositol 3-kinase (PI3K) signaling pathway, influences follicular development and female fertility, a transgenic mouse model was generated with constitutively active Foxo3a expressed in oocytes. We found that the female transgenic mice were infertile, which was caused by retarded oocyte growth and follicular development, and anovulation. Further mechanistic studies revealed that the constitutively active Foxo3a in oocytes caused a dramatic reduction in the expression of bone morphogenic protein 15 (Bmp15), connexin 37 and connexin 43, which are important molecules for the establishment of paracrine and gap junction communications in follicles. Foxo3a was also found to facilitate the nuclear localization of p27(kip1) in oocytes, a cyclin-dependent kinase (Cdk) inhibitor that may serve to inhibit oocyte growth. The results from the current study indicate that Foxo3a is an important intra-oocyte signaling molecule that negatively regulates oocyte growth and follicular development. Our study may therefore give some insight into oocyte-borne genetic aberrations that cause defects in follicular development and anovulation in human diseases, such as premature ovarian failure.
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| 10. |
- Liu, Lian, et al.
(författare)
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Phosphorylation and inactivation of glycogen synthase kinase-3 by soluble kit ligand in mouse oocytes during early follicular development.
- 2007
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Ingår i: Journal of Molecular Endocrinology. - : Bioscientifica. - 0952-5041 .- 1479-6813. ; 38:1-2, s. 137-146
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Tidskriftsartikel (refereegranskat)abstract
- Communication between mammalian oocytes and their surrounding granulosa cells through the Kit-Kit ligand (KL, or stem cell factor, SCF) system has been shown to be crucial for follicular development. Our previous studies (Reddy et al. 2005, Liu et al. 2006) have indicated that the intra-oocyte KL-Kit-PI3 kinase (PI3K)-Akt-Foxo3a cascade may play an important role in follicular activation and early development. In the present study, using in situ hybridization and in vitro culture of growing oocytes from 8-day-old postnatal mice, we have demonstrated that another Akt substrate, glycogen synthase kinase-3 (GSK-3), is expressed in growing oocytes. Also, treatment of cultured mouse oocytes with soluble KL not only leads to increased Akt kinase activity in the oocytes, which can phosphorylate recombinant GSK-3 in vitro, but also leads to phosphorylation of oocyte GSK-3alpha and GSK-3beta, which can result in the inactivation of GSK-3 function in oocytes. In addition, we have shown that the regulation of GSK-3alpha and GSK-3beta in cultured oocytes by soluble KL is accomplished through PI3K, since the PI3K-specific inhibitor LY294002 completely abolished the KL-induced phosphorylation of GSK-3alpha and GSK-3beta. Moreover, blockage of the Kit signaling pathway by a Kit function-blocking antibody, ACK2, resulted in reduced phosphorylation of GSK-3. Taken together, our data suggest that the cascade from granulosa cell-derived KL to Kit-PI3K-Akt-GSK-3 in oocytes may take part in regulation of oocyte growth and early ovarian follicular development.
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| 11. |
- Rajareddy, Singareddy, et al.
(författare)
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p27kip1 (cyclin-dependent kinase inhibitor 1B) controls ovarian development by suppressing follicle endowment and activation and promoting follicle atresia in mice
- 2007
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Ingår i: Molecular Endocrinology. - : The Endocrine Society. - 0888-8809 .- 1944-9917. ; 21:9, s. 2189-2202
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Tidskriftsartikel (refereegranskat)abstract
- In humans, the molecular mechanisms underlying ovarian follicle endowment and activation, which are closely related to the control of female reproduction, occurrence of menopause, and related diseases such as premature ovarian failure, are poorly understood. In the current study, we provide several lines of genetic evidence that the cyclin-dependent kinase (Cdk) inhibitor 1B (commonly known as p27kip1 or p27) controls ovarian development in mice by suppressing follicle endowment and activation, and by promoting follicle death. In p27-deficient (p27−/−) mice, postnatal follicle assembly was accelerated, and the number of endowed follicles was doubled as compared with p27+/+ mice. Moreover, in p27−/− ovaries the primordial follicle pool was prematurely activated once it was endowed, and at the same time the massive follicular death that occurs before sexual maturity was rescued by loss of p27. In early adulthood, however, the overactivated follicular pool in p27−/− ovaries was largely depleted, causing premature ovarian failure. Furthermore, we have extensively studied the molecular mechanisms underlying the above-mentioned phenotypes seen in p27−/− ovaries and have found that p27 controls follicular development by several distinct mechanisms at different stages of development of the ovary. For example, p27 controls oocyte growth by suppressing the functions of Cdk2/Cdc2-cyclin A/E1 in oocytes that are arrested at the diplotene stage of meiosis I. This function of p27 is distinct from its well-known role as a suppressor of cell cycle progression. In addition, we have found that p27 activates the caspase-9-caspase-3-caspase-7-poly (ADP-ribose) polymeraseapoptotic cascade by inhibiting Cdk2/Cdc2-cyclin A/B1 kinase activities in follicles, thereby inducing follicle atresia. Our results suggest that the p27 gene is important in determining mammalian ovarian development. This study therefore provides insight into ovary-borne genetic aberrations that cause defects in folliculogenesis and infertility in humans.
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| 12. |
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| 13. |
- Reddy, Pradeep, et al.
(författare)
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Formation of E-cadherin-mediated cell-cell adhesion activates AKT and mitogen activated protein kinase via phosphatidylinositol 3 kinase and ligand-independent activation of epidermal growth factor receptor in ovarian cancer cells
- 2005
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Ingår i: Mol Endocrinol. - : The Endocrine Society. - 0888-8809. ; 19:10, s. 2564-2578
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Tidskriftsartikel (refereegranskat)abstract
- E-cadherin is a well characterized adhesion molecule that plays a major role in epithelial cell adhesion. Based on findings that expression of E-cadherin is frequently lost in human epithelial cancers, it has been implicated as a tumor suppressor in carcinogenesis of most human epithelial cancers. However, in ovarian cancer development, our data from the current study showed that E-cadherin expression is uniquely elevated in 86.5% of benign, borderline, and malignant ovarian carcinomas irrespective of the degree of differentiation, whereas normal ovarian samples do not express E-cadherin. Thus, we hypothesize that E-cadherin may play a distinct role in the development of ovarian epithelial cancers. Using an E-cadherin-expressing ovarian cancer cell line OVCAR-3, we have demonstrated for the first time that the establishment of E-cadherin mediated cell-cell adhesions leads to the activation of Akt and MAPK. Akt activation is mediated through the activation of phosphatidylinositol 3 kinase, and both Akt and MAPK activation are mediated by an E-cadherin adhesion-induced ligand-independent activation of epidermal growth factor receptor. We have also demonstrated that suppression of E-cadherin function leads to retarded cell proliferation and reduced viability. We therefore suggest that the concurrent formation of E-cadherin adhesion and activation of downstream proliferation signals may enhance the proliferation and survival of ovarian cancer cells. Our data partly explain why E-cadherin is always expressed during ovarian tumor development and progression.
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| 14. |
- Reddy, Pradeep, et al.
(författare)
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Mechanisms maintaining the dormancy and survival of mammalian primordial follicles
- 2010
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Ingår i: Trends in endocrinology and metabolism. - : Elsevier BV. - 1043-2760 .- 1879-3061. ; 21:2, s. 96-103
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Tidskriftsartikel (refereegranskat)abstract
- To preserve the length of a woman's reproductive life it is essential that the majority of her ovarian primordial follicles are maintained in a quiescent state to provide a reserve for continuous reproductive success. The mechanisms maintaining the dormancy and survival of primordial follicles have been a mystery for decades. In recent years information provided by genetically modified mouse models has revealed a number of molecules whose functions are indispensable for the maintenance of follicular quiescence (including PTEN, Tsc1, Tsc2, Foxo3a, p27) and survival (PI3K signaling). Here we summarize this updated information, which hopefully will lead to a better understanding of the pathophysiology of the human ovary and provide potential therapeutic options for some types of infertility.
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| 15. |
- Bravo, L, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 16. |
- Tabiri, S, et al.
(författare)
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- 2021
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swepub:Mat__t
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