Conjugated linoleic acids attenuate FSH- and IGF1-stimulated cell proliferation; IGF1, GATA4, and aromatase expression; and estradiol-17β production in buffalo granulosa cells involving PPARγ, PTEN, and PI3K/Akt
TL;DR: This study demonstrated the cross talk between downstream signaling of CLA and important hormone regulators of endocrine system, i.e. FSH and IGF1, on buffalo granulosa cell function (proliferation and steroidogenesis) and found that CLA intervenes the IGF1 signaling by decreasing p-Akt.
Abstract: Conjugated linoleic acid (CLA) has drawn much interest in last two decades in the area ranging from anticancer activity to obesity. A number of research papers have been published recently with regard to CLA's additional biological functions as reproductive benefits. However, not much is known how this mixture of isomeric compounds mediates its beneficial effects particularly on fertility. In this study, we demonstrated the cross talk between downstream signaling of CLA and important hormone regulators of endocrine system, i.e. FSH and IGF1, on buffalo granulosa cell function (proliferation and steroidogenesis). Experiments were performed in primary serum-free buffalo granulosa cell culture, where cells were incubated with CLA in combination with FSH (25 ng/ml) and IGF1 (50 ng/ml). Results showed that 10 μM CLA inhibits FSH- and IGF1-induced granulosa cell proliferation; aromatase, GATA4, and IGF1 mRNA; and estradiol-17β production. Western blot analysis of total cell lysates revealed that CLA intervenes the IGF1 signaling by decreasing p-Akt. In addition, CLA was found to upregulate peroxisome proliferator-activated receptor-gamma (PPARG) and phosphatase and tensin homolog (PTEN) level in granulosa cells. Further study using PPARG- and PTEN-specific inhibitors supports the potential role of CLA in granulosa cell proliferation and steroidogenesis involving PPARG, PTEN, and PI3K/Akt pathway.
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TL;DR: Evidence demonstrating a link between obesity and breast cancer has led to the investigation of metabolic pathways as novel regulators of estrogen production, including pathways that can be targeted to inhibit aromatase specifically within the breast.
89 citations
TL;DR: The measurement of levels of PI3K-Akt pathway components in FCs from ovarian follicles carrying oocytes with distinct developmental competences is a useful tool to identify putative molecular pathways involved in the acquisition of oocyte competence.
Abstract: The ovarian follicle encloses oocytes in a microenvironment throughout their growth and acquisition of competence. Evidence suggests a dynamic interplay among follicular cells and oocytes, since they are constantly exchanging "messages". We dissected bovine ovarian follicles and recovered follicular cells (FCs-granulosa and cumulus cells) and cumulus-oocyte complexes (COCs) to investigate whether the PI3K-Akt signaling pathway impacted oocyte quality. Following follicle rupture, COCs were individually selected for in vitro cultures to track the follicular cells based on oocyte competence to reach the blastocyst stage after parthenogenetic activation. Levels of PI3K-Akt signaling pathway components in FCs correlated with oocyte competence. This pathway is upregulated in FCs from follicles with high-quality oocytes that are able to reach the blastocyst stage, as indicated by decreased levels of PTEN and increased levels of the PTEN regulators bta-miR-494 and bta-miR-20a. Using PI3K-Akt responsive genes, we showed decreased FOXO3a levels and BAX levels in lower quality groups, indicating changes in cell cycle progression, oxidative response and apoptosis. Based on these results, the measurement of levels of PI3K-Akt pathway components in FCs from ovarian follicles carrying oocytes with distinct developmental competences is a useful tool to identify putative molecular pathways involved in the acquisition of oocyte competence.
64 citations
TL;DR: The results strongly suggest that deregulation of miR-320a/RUNX2/CYP11A1 (CYP19A1) cascade plays an important role in the development of estrogen deficiency in human CCs.
49 citations
TL;DR: Interaction between immune and endocrine system is a diverse process influencing cellular function and homeostasis in animals, and high IGF-1 levels may combat infection during critical periods like NEB in postpartum dairy animals.
28 citations
TL;DR: This review presents a revised understanding of the effects of different fatty acids on the female reproductive success, which may allow other researchers and clinicians to investigate the mechanisms for treating metabolic stress-induced female infertility.
Abstract: A majority of common metabolic diseases can result in excessive lipolysis, leading to elevated levels of non-esterified fatty acids (NEFAs) in the body fluids. In females, increased NEFA levels in the follicular fluid markedly alter the functions of intrafollicular cells such as granulosa cells (GCs) and oocytes. Therefore, elevated levels of NEFAs have been suggested to be a significant player of subfertility in females of both human and economically important animal species such as cattle, buffalo, sheep, pig, chicken, and dog. However, the effects imposed by saturated and unsaturated fatty acids (SFAs and UFAs) on ovarian follicles are controversial. The present review emphasizes that SFAs induce apoptosis in granulosa and cumulus cells of ovarian follicles in different species. They further could adversely affect oocyte maturation and developmental competence. Many types of UFAs affect steroidogenesis and proliferation processes and could be detrimental for follicular cells, especially when at elevated concentrations. Interestingly, monounsaturated fatty acids (MUFAs) appear to contribute to the etiology of the polycystic ovarian syndrome (PCOS) as they were found to induce the transcription and translation of the androgenic transcription factor SOX9 while downregulating its estrogenic counterpart FOXL2 in GCs. Overall, this review presents our revised understanding of the effects of different fatty acids on the female reproductive success, which may allow other researchers and clinicians to investigate the mechanisms for treating metabolic stress-induced female infertility.
26 citations
Cites background from "Conjugated linoleic acids attenuate..."
...Similar to OA, CLA, an isomer of LA has been found to affect FSH and IGF-1 induced steroidogenesis by downregulating the transcription of CYP19A1, insulin-like growth factor 1 receptor (IGFR1) and GATA4 genes [51]....
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...These observed effects were attributed to decreased levels of Akt phosphorylation and increased protein abundance of PPARG and phosphatase and tensin homolog (PTEN) by CLA in buffalo GCs [51]....
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TL;DR: The results clearly delineate the technical boundaries of current approaches for quantitative analysis of protein expression and reveal that simple deduction from mRNA transcript analysis is insufficient to predict protein expression levels from quantitative mRNA data.
Abstract: The description of the state of a biological system by the quantitative measurement of the system constituents is an essential but largely unexplored area of biology. With recent technical advances including the development of differential display-PCR (21), of cDNA microarray and DNA chip technology (20, 27), and of serial analysis of gene expression (SAGE) (34, 35), it is now feasible to establish global and quantitative mRNA expression profiles of cells and tissues in species for which the sequence of all the genes is known. However, there is emerging evidence which suggests that mRNA expression patterns are necessary but are by themselves insufficient for the quantitative description of biological systems. This evidence includes discoveries of posttranscriptional mechanisms controlling the protein translation rate (15), the half-lives of specific proteins or mRNAs (33), and the intracellular location and molecular association of the protein products of expressed genes (32).
Proteome analysis, defined as the analysis of the protein complement expressed by a genome (26), has been suggested as an approach to the quantitative description of the state of a biological system by the quantitative analysis of protein expression profiles (36). Proteome analysis is conceptually attractive because of its potential to determine properties of biological systems that are not apparent by DNA or mRNA sequence analysis alone. Such properties include the quantity of protein expression, the subcellular location, the state of modification, and the association with ligands, as well as the rate of change with time of such properties. In contrast to the genomes of a number of microorganisms (for a review, see reference 11) and the transcriptome of Saccharomyces cerevisiae (35), which have been entirely determined, no proteome map has been completed to date.
The most common implementation of proteome analysis is the combination of two-dimensional gel electrophoresis (2DE) (isoelectric focusing-sodium dodecyl sulfate [SDS]-polyacrylamide gel electrophoresis) for the separation and quantitation of proteins with analytical methods for their identification. 2DE permits the separation, visualization, and quantitation of thousands of proteins reproducibly on a single gel (18, 24). By itself, 2DE is strictly a descriptive technique. The combination of 2DE with protein analytical techniques has added the possibility of establishing the identities of separated proteins (1, 2) and thus, in combination with quantitative mRNA analysis, of correlating quantitative protein and mRNA expression measurements of selected genes.
The recent introduction of mass spectrometric protein analysis techniques has dramatically enhanced the throughput and sensitivity of protein identification to a level which now permits the large-scale analysis of proteins separated by 2DE. The techniques have reached a level of sensitivity that permits the identification of essentially any protein that is detectable in the gels by conventional protein staining (9, 29). Current protein analytical technology is based on the mass spectrometric generation of peptide fragment patterns that are idiotypic for the sequence of a protein. Protein identity is established by correlating such fragment patterns with sequence databases (10, 22, 37). Sophisticated computer software (8) has automated the entire process such that proteins are routinely identified with no human interpretation of peptide fragment patterns.
In this study, we have analyzed the mRNA and protein levels of a group of genes expressed in exponentially growing cells of the yeast S. cerevisiae. Protein expression levels were quantified by metabolic labeling of the yeast proteins to a steady state, followed by 2DE and liquid scintillation counting of the selected, separated protein species. Separated proteins were identified by in-gel tryptic digestion of spots with subsequent analysis by microspray liquid chromatography-tandem mass spectrometry (LC-MS/MS) and sequence database searching. The corresponding mRNA transcript levels were calculated from SAGE frequency tables (35).
This study, for the first time, explores a quantitative comparison of mRNA transcript and protein expression levels for a relatively large number of genes expressed in the same metabolic state. The resultant correlation is insufficient for prediction of protein levels from mRNA transcript levels. We have also compared the relative amounts of protein and mRNA with the respective codon bias values for the corresponding genes. This comparison indicates that codon bias by itself is insufficient to accurately predict either the mRNA or the protein expression levels of a gene. In addition, the results demonstrate that only highly expressed proteins are detectable by 2DE separation of total cell lysates and that therefore the construction of complete proteome maps with current technology will be very challenging, irrespective of the type of organism.
3,947 citations
"Conjugated linoleic acids attenuate..." refers background in this paper
...Moreover, it is a well-established fact that there is frequently a lack of concordance between mRNA and protein concentration data (Gygi et al. 1999, Schmidt et al. 2007)....
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TL;DR: It is demonstrated that overexpression of PTEN, a putative tumor suppressor, reduced insulin-induced PtdIns(3,4,5)P3 production in human 293 cells without effecting insulin- induced phosphoinositide 3-kinase activation.
3,069 citations
"Conjugated linoleic acids attenuate..." refers background in this paper
...Marei et al. (2009) showed that linoleic acid influenced follicular development....
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TL;DR: While not definitively established, roles for placental lactogen and prolactin are attractive possibilities in homeorhetic regulation of maternal tissues to support pregnancy and the initiation of lactaion, respectively.
1,697 citations
"Conjugated linoleic acids attenuate..." refers background in this paper
...Fertility in postpartum period is a major concern because after parturition most of the nutrients are driven toward milk production than follicular maturation (Baumen & Currie 1980, Leroy et al. 2008)....
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TL;DR: The effects of CLA appear to be due in part to reduced fat deposition and increased lipolysis in adipocytes, possibly coupled with enhanced fatty acid oxidation in both muscle cells and adipocytes.
Abstract: The effects of conjugated linoleic acid (CLA) on body composition were investigated. ICR mice were fed a control diet containing 5.5% corn oil or a CLA-supplemented diet (5.0% corn oil plus 0.5% CLA). Mice fed CLA-supplemented diet exhibited 57% and 60% lower body fat and 5% and 14% increased lean body mass relative to controls (P < 0.05). Total carnitine palmitoyltransferase activity was increased by dietary CLA supplementation in both fat pad and skeletal muscle; the differences were significant for fat pad of fed mice and skeletal muscle of fasted mice. In cultured 3T3-L1 adipocytes CLA treatment (1 x 10(-4)M) significantly reduced heparin-releasable lipoprotein lipase activity (-66%) and the intracellular concentrations of triacylglyceride (-8%) and glycerol (-15%), but significantly increased free glycerol in the culture medium (+22%) compared to control (P < 0.05). The effects of CLA on body composition appear to be due in part to reduced fat deposition and increased lipolysis in adipocytes, possibly coupled with enhanced fatty acid oxidation in both muscle cells and adipocytes.
1,193 citations
"Conjugated linoleic acids attenuate..." refers result in this paper
...A number of studies have supported the role of CLA as anticarcinogenic (Devery et al. 2001, Pariza et al. 2001), antiatherogenic (Lee et al. 1994, Nicolosi et al. 1997), antidiabetic (Houseknecht et al. 1998), and antiobesity (Park et al. 1997) agent....
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TL;DR: The effects of CLA on body composition and growth/feed efficiency appear to be due to separate biochemical mechanisms, and it is shown that a 19-carbon CLA cognate inhibits lipoprotein lipase activity as effectively as CLA in cultured 3T3-L1 adipocytes.
1,077 citations
"Conjugated linoleic acids attenuate..." refers result in this paper
...A number of studies have supported the role of CLA as anticarcinogenic (Devery et al. 2001, Pariza et al. 2001), antiatherogenic (Lee et al. 1994, Nicolosi et al. 1997), antidiabetic (Houseknecht et al. 1998), and antiobesity (Park et al. 1997) agent....
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