The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Aleksandar Rajkovic - One of the best experts on this subject based on the ideXlab platform.
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TAF4b targets the promoters of critical meiosis and oogenesis regulators.
2016Co-Authors: Kathryn J. Grive, Aleksandar Rajkovic, Kayla Golnoski, Eric A. Gustafson, Kimberly A. Seymour, Melody Baddoo, Christoph Schorl, Alexander S. Brodsky, Richard N. FreimanAbstract:(A) Wild-type E18.5 ovarian chromatin pulled down by antibodies against TAF4b or IgG and then qPCR-amplified using primers against the proximal promoters of Stra8, Dazl, Figlα, NOBOX and a non-genic region upstream of NOBOX. qPCR demonstrates enriched recovery of these proximal promoters with TAF4b-precipitated chromatin relative to IgG. (B) The NOBOX proximal promoter, in particular, demonstrates enrichment for TAF4b, in contrast to a non-genic region upstream of the promoter. For all analyses, data from each primer set were normalized to the E18.5 mouse ovary genomic DNA input levels and represented as a percentage of that DNA input. Each qPCR reaction was performed in triplicate and averaged. Error bars indicate the normalized standard deviation resulting from experimental triplicate qPCR reactions.
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TAF4b Regulates Oocyte-Specific Genes Essential for Meiosis
2016Co-Authors: Kathryn J. Grive, Aleksandar Rajkovic, Kayla Golnoski, Eric A. Gustafson, Kimberly A. Seymour, Melody Baddoo, Christoph Schorl, Alexander S. Brodsky, Richard N. FreimanAbstract:TAF4b is a gonadal-enriched subunit of the general transcription factor TFIID that is implicated in promoting healthy ovarian aging and female fertility in mice and humans. To further explore the potential mechanism of TAF4b in promoting ovarian follicle development, we analyzed global gene expression at multiple time points in the human fetal ovary. This computational analysis revealed coordinate expression of human TAF4B and critical regulators and effectors of meiosis I including SYCP3, YBX2, STAG3, and DAZL. To address the functional relevance of this analysis, we turned to the embryonic Taf4b-deficient mouse ovary where, for the first time, we demonstrate, severe deficits in prophase I progression as well as asynapsis in Taf4b-deficient oocytes. Accordingly, TAF4b occupies the proximal promoters of many essential meiosis and oogenesis regulators, including Stra8, Dazl, Figla, and NOBOX, and is required for their proper expression. These data reveal a novel TAF4b function in regulating a meiotic gene expression program in early mouse oogenesis, and support the existence of a highly conserved TAF4b-dependent gene regulatory network promoting early oocyte development in both mice and women.
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lhx8 regulates primordial follicle activation and postnatal folliculogenesis
BMC Biology, 2015Co-Authors: Hitomi Suzuki, Krishna Jagarlamudi, Kayla Golnoski, Megan M Mcguire, Rita Lopes, Vassilis Pachnis, Aleksandar RajkovicAbstract:Background The early stages of ovarian follicle formation—beginning with the breakdown of germ cell cysts and continuing with the formation of primordial follicles and transition to primary and secondary follicles—are critical in determining reproductive life span and fertility. Previously, we discovered that global knockouts of germ cell-specific transcriptional co-regulators Sohlh1, Sohlh2, Lhx8, and NOBOX, cause rapid oocyte loss and ovarian failure. Also factors such as NOBOX and Sohlh1 are associated with human premature ovarian failure. In this study, we developed a conditional knockout of Lhx8 to study oocyte-specific pathways in postnatal folliculogenesis.
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premature ovarian failure in NOBOX deficient mice is caused by defects in somatic cell invasion and germ cell cyst breakdown
Journal of Assisted Reproduction and Genetics, 2011Co-Authors: Agnieszka Lechowska, Youngsok Choi, Szczepan M Bilinski, Yonghyun Shin, Malgorzata Kloc, Aleksandar RajkovicAbstract:PURPOSE: To understand the mechanism of premature ovarian failure (POF). METHODS: The ultrastructural (electron microscopy) analysis of primordial ovarian follicles in NOBOX deficient mice. RESULTS: We studied, for the first time, the fate of oogonia in embryonic (prenatal) mouse ovaries and showed that the abolishment of the transition from germ cell cysts to primordial follicles in the ovaries of NOBOX deficient mice is caused by defects in germ cell cyst breakdown, leading to the formation of syncytial follicles instead of primordial follicles. CONCLUSIONS: These results indicate that POF syndrome in NOBOX deficient mice results from the faulty signaling between somatic and germ line components during embryonic development. In addition, the extremely unusual and abnormal presence of adherens junctions between unseparated oocytes within syncytial follicles indicates that faulty communication between somatic and germ cells is involved in, or leads to, abnormalities in the cell adhesion program.
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germ cell specific transcriptional regulator sohlh2 is essential for early mouse folliculogenesis and oocyte specific gene expression
Biology of Reproduction, 2008Co-Authors: Youngsok Choi, Daniel Yuan, Aleksandar RajkovicAbstract:We previously discovered a germ cell-specific spermatogenesis and oogenesis basic helix-loop-helix transcription factor, Sohlh2. We generated Sohlh2-deficient mice to understand physiologic consequences of Sohlh2 deletion. We discovered that Sohlh2-knockout adult female mice are infertile due to lack of ovarian follicles. Sohlh2-deficient ovaries can form primordial follicles and, despite limited oocyte growth, do not differentiate surrounding granulosa cells into cuboidal and multilayered structures. Oocytes are rapidly lost in Sohlh2-deficient ovaries, and few are present by 14 days of postnatal life. However, the primordial oocytes are abnormal at the molecular level because they misexpress numerous germ cell- and oocyte-specific genes, including Sohlh1, NOBOX, Figla, Gdf9, Pou5f1, Zp1, Zp3, Kit, Oosp1, Nlrp14, H1foo, and Stra8. Our findings show that Sohlh2 is a critical factor for maintenance and differentiation of the oocyte during early oogenesis.
Cory D Champagne - One of the best experts on this subject based on the ideXlab platform.
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glucose oxidation and nonoxidative glucose disposal during prolonged fasts of the northern elephant seal pup mirounga angustirostris
American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2012Co-Authors: Dorian S Houser, Daniel E Crocker, Michael S Tift, Cory D ChampagneAbstract:Elephant seal weanlings demonstrate rates of endogenous glucose production (EGP) during protracted fasts that are higher than predicted on the basis of mass and time fasting. To determine the nonox...
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glucose oxidation and nonoxidative glucose disposal during prolonged fasts of the northern elephant seal pup mirounga angustirostris
American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2012Co-Authors: Dorian S Houser, Daniel E Crocker, Michael S Tift, Cory D ChampagneAbstract:Elephant seal weanlings demonstrate rates of endogenous glucose production (EGP) during protracted fasts that are higher than predicted on the basis of mass and time fasting. To determine the nonox...
Youngsok Choi - One of the best experts on this subject based on the ideXlab platform.
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DOI 10.1095/biolreprod.108.069393 Lim Homeobox Gene, Lhx8, Is Essential for Mouse Oocyte Differentiation and Survival1
2016Co-Authors: Youngsok Choi, Daniel J Ballow, Yun Xin, Ar RajkovicAbstract:Lhx8 is a member of the LIM-homeobox transcription factor family and preferentially expressed in oocytes and germ cells within the mouse ovary. We discovered that Lhx8 knockout females lose oocytes within 7 days after birth. At the time of birth, histological examination shows that Lhx8-deficient (Lhx8/) ovaries are grossly similar to the newborn wild-type ovaries. Lhx8/ ovaries fail to maintain the primordial follicles, and the transition from primordial to growing follicles does not occur. Lhx8/ ovaries misexpress oocyte-specific genes, such as Gdf9, Pou5f1, and NOBOX. Very rapid loss of oocytes may partly be due to the drastic downregulation of Kit and Kitl in Lhx8/ ovaries. We compared Lhx8/ and wild-type ovaries using an Affymetrix 430 2.0 microarray platform. A total of 80 (44%) of 180 of the genes downregulated more than 5-fold in Lhx8/ ovaries were preferentially expressed in oocytes, whereas only 3 (2%) of 146 genes upregulated more than 5-fold in the absence of Lhx8 were preferentially expressed in oocytes. In addition, the comparison of genes regulated in Lhx8/ and NOBOX/ newborn ovaries discovered a common set of 34 genes whose expression level was affected in both Lhx8- and NOBOX-deficient mice. Our findings show that Lhx8 is a critical factor for maintenance and differentiation of the oocyte during early oogenesis, and it acts in part by downregulating the NOBOX pathway. developmental biology, gamete biology, gene regulation, KIT
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1 Microarray analyses of newborn mouse ovaries lacking NOBOX
2016Co-Authors: Youngsok Choi, Daniel J Ballow, Yingying Qin, Michael F. Berger, Martha LAbstract:Short Title: NOBOX regulates expression of oocyte-specific genes Summary Sentence: NOBOX activates expression of oocyte-specific genes and represses transcription of genes preferentially expressed in testes
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premature ovarian failure in NOBOX deficient mice is caused by defects in somatic cell invasion and germ cell cyst breakdown
Journal of Assisted Reproduction and Genetics, 2011Co-Authors: Agnieszka Lechowska, Youngsok Choi, Szczepan M Bilinski, Yonghyun Shin, Malgorzata Kloc, Aleksandar RajkovicAbstract:PURPOSE: To understand the mechanism of premature ovarian failure (POF). METHODS: The ultrastructural (electron microscopy) analysis of primordial ovarian follicles in NOBOX deficient mice. RESULTS: We studied, for the first time, the fate of oogonia in embryonic (prenatal) mouse ovaries and showed that the abolishment of the transition from germ cell cysts to primordial follicles in the ovaries of NOBOX deficient mice is caused by defects in germ cell cyst breakdown, leading to the formation of syncytial follicles instead of primordial follicles. CONCLUSIONS: These results indicate that POF syndrome in NOBOX deficient mice results from the faulty signaling between somatic and germ line components during embryonic development. In addition, the extremely unusual and abnormal presence of adherens junctions between unseparated oocytes within syncytial follicles indicates that faulty communication between somatic and germ cells is involved in, or leads to, abnormalities in the cell adhesion program.
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germ cell specific transcriptional regulator sohlh2 is essential for early mouse folliculogenesis and oocyte specific gene expression
Biology of Reproduction, 2008Co-Authors: Youngsok Choi, Daniel Yuan, Aleksandar RajkovicAbstract:We previously discovered a germ cell-specific spermatogenesis and oogenesis basic helix-loop-helix transcription factor, Sohlh2. We generated Sohlh2-deficient mice to understand physiologic consequences of Sohlh2 deletion. We discovered that Sohlh2-knockout adult female mice are infertile due to lack of ovarian follicles. Sohlh2-deficient ovaries can form primordial follicles and, despite limited oocyte growth, do not differentiate surrounding granulosa cells into cuboidal and multilayered structures. Oocytes are rapidly lost in Sohlh2-deficient ovaries, and few are present by 14 days of postnatal life. However, the primordial oocytes are abnormal at the molecular level because they misexpress numerous germ cell- and oocyte-specific genes, including Sohlh1, NOBOX, Figla, Gdf9, Pou5f1, Zp1, Zp3, Kit, Oosp1, Nlrp14, H1foo, and Stra8. Our findings show that Sohlh2 is a critical factor for maintenance and differentiation of the oocyte during early oogenesis.
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lim homeobox gene lhx8 is essential for mouse oocyte differentiation and survival
Biology of Reproduction, 2008Co-Authors: Youngsok Choi, Daniel J Ballow, Yun Xin, Aleksandar RajkovicAbstract:Lhx8 is a member of the LIM-homeobox transcription factor family and preferentially expressed in oocytes and germ cells within the mouse ovary. We discovered that Lhx8 knockout females lose oocytes within 7 days after birth. At the time of birth, histological examination shows that Lhx8-deficient (Lhx8−/−) ovaries are grossly similar to the newborn wild-type ovaries. Lhx8−/− ovaries fail to maintain the primordial follicles, and the transition from primordial to growing follicles does not occur. Lhx8−/− ovaries misexpress oocyte-specific genes, such as Gdf9, Pou5f1, and NOBOX. Very rapid loss of oocytes may partly be due to the drastic downregulation of Kit and Kitl in Lhx8−/− ovaries. We compared Lhx8−/− and wild-type ovaries using an Affymetrix 430 2.0 microarray platform. A total of 80 (44%) of 180 of the genes downregulated more than 5-fold in Lhx8−/− ovaries were preferentially expressed in oocytes, whereas only 3 (2%) of 146 genes upregulated more than 5-fold in the absence of Lhx8 were preferentially expressed in oocytes. In addition, the comparison of genes regulated in Lhx8−/− and NOBOX−/− newborn ovaries discovered a common set of 34 genes whose expression level was affected in both Lhx8- and NOBOX-deficient mice. Our findings show that Lhx8 is a critical factor for maintenance and differentiation of the oocyte during early oogenesis, and it acts in part by downregulating the NOBOX pathway.
Ryunosuke Yoshino - One of the best experts on this subject based on the ideXlab platform.
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non steroidal inhibitors of drosophila melanogaster steroidogenic glutathione s transferase noppera bo
Journal of Pesticide Science, 2021Co-Authors: Kotaro Koiwai, Kazue Inaba, Kana Morohashi, Hirotatsu Kojima, Takayoshi Okabe, Ryunosuke Yoshino, Kana Ebihara, Takatsugu Hirokawa, Taiki Nampo, Yuuta FujikawaAbstract:Insect growth regulators (IGRs) can be developed by elucidating the molecular mechanisms of insect-specific biological events. Because insect molting, and metamorphosis are controlled by ecdysteroids, their biosynthetic pathways can serve as targets for IGR development. The glutathione S-transferase Noppera-bo (Nobo), which is conserved in dipteran and lepidopteran species, plays an essential role in ecdysteroid biosynthesis. Our previous study using 17β-estradiol as a molecular probe revealed that Asp113 of Drosophila melanogaster Nobo (DmNobo) is essential for its biological function. However, to develop IGRs with a greater Nobo inhibitory activity than 17β-estradiol, further structural information is warranted. Here, we report five novel non-steroidal DmNobo inhibitors. Analysis of crystal structures of complexes revealed that DmNobo binds these inhibitors in an Asp113-independent manner. Among amino acid residues at the substrate-recognition site, conformation of conserved Phe39 was dynamically altered upon inhibitor binding. Therefore, these inhibitors can serve as seed compounds for IGR development.
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an integrated approach to unravel a crucial structural property required for the function of the insect steroidogenic halloween protein noppera bo
Journal of Biological Chemistry, 2020Co-Authors: Kotaro Koiwai, Kazue Inaba, Kana Morohashi, Sora Enya, Reina Arai, Hirotatsu Kojima, Takayoshi Okabe, Yuuta Fujikawa, Hideshi Inoue, Ryunosuke YoshinoAbstract:Ecdysteroids are the principal steroid hormones essential for insect development and physiology. In the last 18 years, several enzymes responsible for ecdysteroid biosynthesis encoded by Halloween genes were identified and genetically and biochemically characterized. However, the tertiary structures of these proteins have not yet been characterized. Here, we report the results of an integrated series of in silico, in vitro, and in vivo analyses of the Halloween GST protein Noppera-bo (Nobo). We determined crystal structures of Drosophila melanogaster Nobo (DmNobo) complexed with GSH and 17β-estradiol, a DmNobo inhibitor. 17β-Estradiol almost fully occupied the putative ligand-binding pocket and a prominent hydrogen bond formed between 17β-estradiol and Asp-113 of DmNobo. We found that Asp-113 is essential for 17β-estradiol–mediated inhibition of DmNobo enzymatic activity, as 17β-estradiol did not inhibit and physically interacted less with the D113A DmNobo variant. Asp-113 is highly conserved among Nobo proteins, but not among other GSTs, implying that this residue is important for endogenous Nobo function. Indeed, a homozygous nobo allele with the D113A substitution exhibited embryonic lethality and an undifferentiated cuticle structure, a phenocopy of complete loss-of-function nobo homozygotes. These results suggest that the nobo family of GST proteins has acquired a unique amino acid residue that appears to be essential for binding an endogenous sterol substrate to regulate ecdysteroid biosynthesis. To the best of our knowledge, ours is the first study describing the structural characteristics of insect steroidogenic Halloween proteins. Our findings provide insights relevant for applied entomology to develop insecticides that specifically inhibit ecdysteroid biosynthesis.
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an integrated approach unravels a crucial structural property for the function of the insect steroidogenic halloween protein noppera bo
bioRxiv, 2019Co-Authors: Kotaro Koiwai, Kazue Inaba, Kana Morohashi, Sora Enya, Reina Arai, Hirotatsu Kojima, Takayoshi Okabe, Yuuta Fujikawa, Hideshi Inoue, Ryunosuke YoshinoAbstract:Abstract Ecdysteroids are the principal insect steroid hormones essential for insect development and physiology. In the last 18 years, several enzymes responsible for ecdysteroid biosynthesis, encoded by Halloween genes, have been identified and well characterized, both genetically and biochemically. However, none of these proteins have yet been characterized at the tertiary structure level. Here, we report an integrated in silico, in vitro, and in vivo analyses of the Halloween glutathione S-transferase (GST) protein, Noppera-bo (Nobo). We determine crystal structures of Drosophila melanogaster Nobo (DmNobo) complexed with glutathione and 17β-estradiol, a DmNobo inhibitor. 17β-estradiol almost fully occupied the putative ligand-binding pocket, and a prominent hydrogen bond formed between Asp113 of DmNobo and 17β-estradiol. Asp113 is essential for inhibiting DmNobo enzymatic activity by 17β-estradiol, as 17β-estradiol does not inhibit and physically interacts less with the Asp113Ala DmNobo point mutant. Asp113 is highly conserved among Nobo proteins, but not among other GSTs, implying that Asp113 is important for endogenous Nobo function. Indeed, a homozygous nobo allele possessing the Asp113Ala point mutation exhibits embryonic lethality with undifferentiated cuticle structure, a phenocopy of complete loss-of-function nobo homozygotes. These results suggest that the nobo family of GST proteins has acquired a unique amino acid residue, which seems to be essential for binding an endogenous sterol substrate to regulate ecdysteroid biosynthesis. This is the first study to reveal the structural characteristics of insect steroidogenic Halloween proteins. This study also provides basic insight into applied entomology for developing a new type of insecticides that specifically inhibit ecdysteroid biosynthesis. Significance Statement Insect molting and metamorphosis are drastic and dynamic biological processes and, therefore, have fascinated many scientists. Ecdysteroids represent one class of insect hormones that are indispensable for inducing molting and metamorphosis. It is well known that proteins responsible for catalyzing ecdysteroid biosynthesis reactions are encoded by “Halloween” genes, most of which have names of ghosts and phantoms. However, no studies have focused on the structural properties of these biosynthetic proteins. In this study, we addressed this unsolved issue and successfully unraveled a structural property that is crucial for the function of the fruit fly Halloween protein, Noppera-bo (a Japanese faceless ghost). This is the first study to reveal the structural characteristics of an insect steroidogenic Halloween protein.
Dorian S Houser - One of the best experts on this subject based on the ideXlab platform.
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glucose oxidation and nonoxidative glucose disposal during prolonged fasts of the northern elephant seal pup mirounga angustirostris
American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2012Co-Authors: Dorian S Houser, Daniel E Crocker, Michael S Tift, Cory D ChampagneAbstract:Elephant seal weanlings demonstrate rates of endogenous glucose production (EGP) during protracted fasts that are higher than predicted on the basis of mass and time fasting. To determine the nonox...
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glucose oxidation and nonoxidative glucose disposal during prolonged fasts of the northern elephant seal pup mirounga angustirostris
American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2012Co-Authors: Dorian S Houser, Daniel E Crocker, Michael S Tift, Cory D ChampagneAbstract:Elephant seal weanlings demonstrate rates of endogenous glucose production (EGP) during protracted fasts that are higher than predicted on the basis of mass and time fasting. To determine the nonox...