Placental-Derived Regulators and the Complex Control of Luteal Cell Function

Gibori, Geula; Khan, Iqbal; Ml, Warshaw; Mp, McLean; Tk, Puryear; Nelson, Scott E.; Tj, Durkee; Azhar, Salman; Steinschneider, Assaf; Mc, Rao

doi:10.1016/b978-0-12-571144-9.50016-8

Cited by 73 publications

(78 citation statements)

References 165 publications

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“…Luteal cell function is greatly affected by locally produced estradiol, which stimulates both progesterone biosynthesis and luteal cell hypertrophy [67]. As shown in figure 3, luteal aromatase mRNA content is low on day 4 of pregnancy, increases progressively to reach high levels of expression between days 14 and 19, and decreases from day 20 to reach undetectable levels on day 23, the day of parturition [68][69][70].…”

Section: Pregnant Ratsmentioning

confidence: 99%

Aromatase expression in the ovary: Hormonal and molecular regulation

2008

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Summary-Estrogens are synthesized by the aromatase enzyme encoded by the Cyp19a1 gene, which contains an unusually large regulatory region. In most mammals, aromatase expression is under the control of two distinct promoters a gonad-and a brain-specific promoter. In humans, this gene contains 10 tissue-specific promoters that are alternatively used in various cell types and tumors. Each promoter is regulated by a distinct set of regulatory sequences and transcription factors that bind to these specific sequences. The cAMP/PKA/CREB pathway is considered to be the primary signaling cascade through which the gonad Cyp19 promoter is regulated. Very interestingly, in rat luteal cells, the proximal promoter is not controlled in a cAMP dependent manner. Strikingly, these cells express aromatase at high levels similar to those found in preovulatory follicles, suggesting that alternative and powerful mechanisms control aromatase expression in luteal cells and that the rat corpus luteum represents an important paradigm for understanding alternative controls of the aromatase gene. Here, the molecular and cellular mechanisms controlling the expression of the aromatase gene in granulosa and luteal cells are discussed.

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Section: Pregnant Ratsmentioning

confidence: 99%

Aromatase expression in the ovary: Hormonal and molecular regulation

2008

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“…Many attempts have been done to demonstrate the luteotropic action of PRL [13]. Indeed, PRL was proved to have luteotropic activity during pseudopregnancy and in early pregnancy [6,7].…”

Section: Discussionmentioning

confidence: 99%

“…But maternal PRL secretion, which is characterized by two daily surges, is not continued and ceases at mid-pregnancy [25,26] when placental lactogens start to be secreted. The member of the placental PRL family has been assumed to be one of the luteotropic factors during pregnancy after placentation [13]. In accord with this concept, the mid-pregnancy-specific PLs are secreted again in late pregnancy and are associated with the prolonged secretion of progesterone from the corpora lutea beyond the normal pregnancy period in the prolonged pregnancy model, which is developed by induction of a new set of corpora lutea following successive treatment with PMSG and hCG at mid-pregnancy [1,27].…”

Section: Discussionmentioning

confidence: 99%

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Characterization of Rat Mid-Pregnancy-Specific Placental Lactogen Produced by Baculovirus / Insect Cell Expression System

Hirosawa-Takamori

Matsruura

Tanaka

et al. 1999

Journal of Reproduction and Development

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Abstract. The placenta produces prolactin (PRL)-or growth hormone-like hormones known as placental lactogens (PLs) which play roles in the maternal endocrine system and fetal growth development. We previously cloned a cDNA encoding a novel rat PL, PL-I mosaic (PL-Im), which is specifically expressed at mid-pregnancy. In this study, the biological activity of PL-Im was evaluated by producing the recombinant protein (recPL-Im) by means of a baculovirus/insect cell expression system. RecPL-Im demonstrated binding activity for PRL receptor in a radioreceptor assay (RRA) system with rat liver membrane fraction and 125 I-ovine PRL (oPRL). In addition, the activity of recPL-Im is comparable to oPRL in the Nb2 cell proliferation assay. Interestingly, recPLIm stimulated progesterone secretion in a concentration-dependent manner in a primary culture of luteal cells from pregnant rat, whereas oPRL had no effect on luteal cells. The luteotropic function of recPL-Im was accompanied by suppression of the secretion of 20α-dihydroprogesterone (20α-OHP) in the culture. PL-Im therefore has ability to bind PRL-receptor and express PRL-like activity. In addition, recPL-Im has luteotropic hormone (LTH) activity and its activity is qualitatively different from that of PRL.

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“…In contrast, protein phosphatase activity declined between days 7 and 10 of pregnancy and remained low for the remainder of pregnancy (Eyster et al 1998). Both the rise in PKC activity and the decline in protein phosphatase activity in the rat ovary occurred near mid-pregnancy at the time that the control of progesterone synthesis shifts from the pituitary to the placenta (Gibori et al 1988). We had reasoned that since the endogenous inhibitor of PKC is present throughout pregnancy (Eyster 1993), the ovarian protein phosphatase activity must be subject to endogenous regulation in order for changes in PKC activity or content to be recognized by the cell.…”

Section: Introductionmentioning

confidence: 96%

Expression of type 1 and 2A protein phosphatase subunits in the rat corpus luteum across pregnancy

Sheth

Mark

Eyster

2007

Journal of Endocrinology

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This study was undertaken to test the hypothesis that the reduction in protein phosphatase activity that had been observed at mid-pregnancy in the rat corpus luteum (CL) was due to a decrease in expression of one of the catalytic subunits or an increase in one of the B regulatory subunits of the type 2A protein phosphatase (PP2A). Ovaries were collected from rats on days (d) 1, 3, 7, 14, 20, and 21 of pregnancy, and on day 21 after progesterone treatment on day 20 (nZ6). Realtime RT-PCR was used to analyze the expression of the a and b isoforms of the catalytic subunit, the structural A subunit, and three B regulatory subunits of PP2A, as well as the catalytic subunit of PP1. Expression of the a and b catalytic subunits of PP2A was progesterone responsive. Expression of the PP1 catalytic subunit correlated with the previously reported protein phosphatase activity, but PP2A subunits did not. The data suggest that the decreased protein phosphatase activity at mid-pregnancy was due to a decline in expression of the catalytic subunits of PP1 rather than changes in expression of PP2A subunits.

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Placental-Derived Regulators and the Complex Control of Luteal Cell Function

Cited by 73 publications

References 165 publications

Aromatase expression in the ovary: Hormonal and molecular regulation

Aromatase expression in the ovary: Hormonal and molecular regulation

Characterization of Rat Mid-Pregnancy-Specific Placental Lactogen Produced by Baculovirus / Insect Cell Expression System

Expression of type 1 and 2A protein phosphatase subunits in the rat corpus luteum across pregnancy

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