Faculty Bibliography

UNLABELLED:Obesity and malnutrition are associated with decreased fecundity in women. Impaired reproductive capacity in obese women is often attributed to anovulation. However, obese women with ovulatory cycles also have reduced fertility, but the etiology of their impaired reproduction is only partially understood. Accumulating evidence suggests that obesity directly impairs oocyte and embryo quality as well as endometrial receptivity. In obese women, urinary progesterone metabolite excretion is decreased, but in excess of what can be explained by suppressed gonadotropin secretion, suggesting that apart from its central effect obesity may directly affect progesterone (P4) production. These observations have led to the novel hypothesis that obesity directly affects corpus luteum (CL) function. Similarly, we hypothesize that weight loss may contribute to luteal dysfunction. Here, we propose a non-human primate model, the vervet monkey, to examine the effect of weight gain and loss on menstrual cycle parameters and CL gene expression. In this model, weight gain and loss did not significantly alter menstrual cyclicity; however, both induced alterations in the CL transcriptome. In the weight gain monkey, we observed that impaired mid-luteal P4 secretion was associated with downregulation of steroidogenic pathways in CL. Collectively, these preliminary findings support our hypothesis that weight gain and loss may contribute to CL dysfunction. The vervet model described and preliminary observations provide a basis for a larger study to address this important question. Understanding the mechanisms by which weight gain and loss contribute to reproductive dysfunction can assist in the development of targeted treatments to enhance women's reproductive capability when it is desired. ABBREVIATIONS/BACKGROUND:CL: corpus luteum; P4: progesterone; E2: estradiol; PDG: pregnanediol 3-glucoronide; LH: luteinizing hormone; FSH: follicle-stimulating hormone; GnRH: gonadotropin releasing hormone; BMI: body mass index; qrtPCR: quantitative real-time PCR; PGR: progesterone receptor; ART: assisted reproductive technology; IVF: in vitro fertilization; HPO: hypothalamic-pituitary-ovarian axis; MMPs: matrix metalloproteinases Gene symbols: LH receptor (LHGCR); cholesterol side-chain cleavage enzyme (CYP11A1); 3 beta-hydroxysteroid dehydrogenase type II (HSD3B2); steroidogenic acute regulatory protein (STAR); LDL receptor (LDLR); scavenger receptor B1 (SCARB1); ATP-binding cassette sub-family A member 1 (ABCA1); ATP-binding cassette sub-family G member 1 (ABCG1); apolipoprotein A (APOA1); 24 dehydrocholesterol reductase (DHCR24); 3-hydroxy-3-methylglytaryl-CoA reductase (HMGCR); vascular endothelial growth factor A (VEGFA); vascular endothelial growth factor C (VEGFC); vascular endothelial growth factor receptor 1 (VEGFR1); and TIMP metallopeptidase inhibitor 1 (TIMP1); amphiregulin (AREG); epiregulin (EREG); CCAAT/enhancer binding protein alpha (CEBPBA); cAMP responsive element binding protein 3-like 1 (CREB3L1); ADAM metallopeptidase with thrombospodin type 1 motif 1 (ADAMTS1); matrix metallopeptidase 9 (MMP9); cytochrome b-245 beta polypeptide (CYBB or NOX2); NADH oxidase (NCF2 or NOXA2); Fc fragment of IgG receptor IIb (FCGR2B); Fc fragment of IgG receptor IIb (FCGR2C); ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1); RAB27A member RAS oncofamily (RAB27A); hydroxyprostaglandin dehydrogenase (HPGD); prostaglandin-endoperoxidase synthase 1 (PTGS1); integrin B2 (ITGB2); leukotriene A4 hydrolase (LTA4H); radixin (RDX); ezrin (EZR); nuclear receptor subfamily 5 group A member 2 (NR5A2).

The uterine epithelium of mice and humans undergoes cyclical waves of cell proliferation and differentiation under the regulation of estradiol-17β (E2) and progesterone (P4). These epithelial cells respond to E2 with increased protein and DNA synthesis, whereas P4 inhibits only the E2-induced DNA synthetic response. Here we show that E2 regulates protein synthesis in these epithelial cells through activating PKC that in turn stimulates ERK1/2 to phosphorylate and thereby activate the central regulator of protein synthesis mechanistic target of rapamycin (mTOR). This mTOR pathway is not inhibited by P4. Inhibitor studies with an estrogen receptor (ESR1) antagonist showed the dependence of this mTOR pathway on ESR1 but that once activated, a phosphorylation cascade independent of ESR1 propagates the pathway. E2 also stimulates an IGF1 receptor (IGF1R) to PI3 kinase to AKT to GSK-3β pathway required for activation of the canonical cell cycle machinery that is inhibited by P4. PKC activation did not stimulate this pathway nor does inhibition of PKC or ERK1/2 affect it. These studies therefore indicate a mechanism whereby DNA and protein synthesis are regulated by two ESR1-activated pathways that run in parallel with only the one responsible for the initiation of DNA synthesis blocked by P4. Inhibition of mTOR by rapamycin in vivo resulted in inhibition of E2-induced protein and DNA synthesis. Proliferative diseases of the endometrium such as endometriosis and cancer are common and E2 dependent. Thus, defining this mTOR pathway suggests that local (intrauterine or peritoneal) rapamycin administration might be a therapeutic option for these diseases.

Obese women exhibit decreased fertility, high miscarriage rates and dysfunctional corpus luteum (CL), but molecular mechanisms are poorly defined. We hypothesized that weight gain induces alterations in CL gene expression. RNA sequencing was used to identify changes in the CL transcriptome in the vervet monkey (Chlorocebus aethiops) during weight gain. 10 months of high-fat, high-fructose diet (HFHF) resulted in a 20% weight gain for HFHF animals vs. 2% for controls (p = 0.03) and a 66% increase in percent fat mass for HFHF group. Ovulation was confirmed at baseline and after intervention in all animals. CL were collected on luteal day 7-9 based on follicular phase estradiol peak. 432 mRNAs and 9 miRNAs were differentially expressed in response to HFHF diet. Specifically, miR-28, miR-26, and let-7b previously shown to inhibit sex steroid production in human granulosa cells, were up-regulated. Using integrated miRNA and gene expression analysis, we demonstrated changes in 52 coordinately regulated mRNA targets corresponding to opposite changes in miRNA. Specifically, 2 targets of miR-28 and 10 targets of miR-26 were down-regulated, including genes linked to follicular development, steroidogenesis, granulosa cell proliferation and survival. To the best of our knowledge, this is the first report of dietary-induced responses of the ovulating ovary to developing adiposity. The observed HFHF diet-induced changes were consistent with development of a dysfunctional CL and provide new mechanistic insights for decreased sex steroid production characteristic of obese women. MiRNAs may represent novel biomarkers of obesity-related subfertility and potential new avenues for therapeutic intervention.

The etiology and pathogenesis of endometrial polyps (EPs) are only partially understood. To better understand how sex steroids regulate polyp growth, we investigated the messenger RNA (mRNA) expression of the genes of reproductive steroid hormone receptors (estrogen receptors alpha [ERalpha] and beta [ERbeta], G protein-coupled receptor 30 [GPR30], and progesterone receptor [PR]) in EP tissue and autologous normal appearing endometrium (R) Within each patient, the normal appearing endometrial tissue remote from the site of the endometrial polyp (R) was taken as an internal control. Relative expressions of genes of interest within the endometrial polyp were compared to expressions of respective genes within the internal control tissue (i.e. R). R is the abbreviation for normal appearing endometrium in the later calculation formula. Ten patients diagnosed with EP in a tertiary care center were included in this study. Directed biopsies were obtained under hysteroscopy from the EP and from a normal appearing site remote from EP along the opposite uterine wall in each patient. Quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) was used for gene expression profiling in the paired tissue samples. The relative gene expression between EP and normal appearing endometrium in each patient was analyzed with 2(-DeltaDeltaCt) method. We found that ERalpha, ERbeta, GPR30, and PR were expressed in both normal appearing endometrium and EP in each patient. ERalpha, ERbeta, GPR30, and PR showed no difference in relative expression in EP samples compared with paired normal endometrial samples from the same uterine cavity. However, the relative expression of PR correlated with that of GPR30 (r = .70, P = .023), suggesting that the co-expression of PR and GPR30 may be a contributory mechanism in the pathogenesis of EPs at least in a subset of women.

MicroRNAs (miRNAs), a class of small noncoding RNAs that regulate gene expression, have fundamental roles in biological processes, including cell differentiation and proliferation. These small molecules mainly direct either target messenger RNA (mRNA) degradation or translational repression, thereby functioning as gene silencers. Epithelial cells of the uterine lumen and glands undergo cyclic changes under the influence of the sex steroid hormones estradiol-17beta and progesterone. Because the expression of miRNAs in human endometrium has been established, it is important to understand whether miRNAs have a physiological role in modulating the expression of hormonally induced genes. The studies herein establish concomitant differential miRNA and mRNA expression profiles of uterine epithelial cells purified from endometrial biopsy specimens in the late proliferative and midsecretory phases. Bioinformatics analysis of differentially expressed mRNAs revealed cell cycle regulation as the most significantly enriched pathway in the late proliferative-phase endometrial epithelium (P = 5.7 x 10(-15)). In addition, the WNT signaling pathway was enriched in the proliferative phase. The 12 miRNAs (MIR29B, MIR29C, MIR30B, MIR30D, MIR31, MIR193A-3P, MIR203, MIR204, MIR200C, MIR210, MIR582-5P, and MIR345) whose expression was significantly up-regulated in the midsecretory-phase samples were predicted to target many cell cycle genes. Consistent with the role of miRNAs in suppressing their target mRNA expression, the transcript abundance of predicted targets, including cyclins and cyclin-dependent kinases, as well as E2F3 (a known target of MIR210), was decreased. Thus, our findings suggest a role for miRNAs in down-regulating the expression of some cell cycle genes in the secretory-phase endometrial epithelium, thereby suppressing cell proliferation.

Nucleolar channel systems (NCSs) are membranous organelles appearing transiently in the epithelial cell nuclei of postovulatory human endometrium. Their characterization and use as markers for a healthy receptive endometrium have been limited because they are only identifiable by electron microscopy. Here we describe the light microscopic detection of NCSs using immunofluorescence. Specifically, the monoclonal nuclear pore complex antibody 414 shows that NCSs are present in about half of all human endometrial epithelial cells but not in any other cell type, tissue or species. Most nuclei contain only a single NCS of uniform 1 microm diameter indicating a tightly controlled organelle. The composition of NCSs is as unique as their structure; they contain only a subset each of the proteins of nuclear pore complexes, inner nuclear membrane, nuclear lamina and endoplasmic reticulum. Validation of our robust NCS detection method on 95 endometrial biopsies defines a 6-day window, days 19-24 (+/-1) of an idealized 28 day cycle, wherein NCSs occur. Therefore, NCSs precede and overlap with the implantation window and serve as potential markers of uterine receptivity. The immunodetection assay, combined with the hitherto underappreciated prevalence of NCSs, now enables simple screening and further molecular and functional dissection.

We have previously found evidence for linkage as well as allelic and haplotype association between the myelin basic protein (MBP) gene and multiple sclerosis (MS). These findings have, however, not been reproduced in other populations. Here, we have analyzed association between MBP and MS in a new set of 349 Finnish triad families. Families with a parent born in the Southern Ostrobothnian region in western Finland (Bothnia families, n=98) were analyzed as a separate group since our previous studies included a high proportion of patients and families from this high-incidence region. Other families (n=251) were collected at five hospitals in southern, eastern, and northern Finland. The MBP short tandem repeat was genotyped, and haplotype patterns were verified by sequencing. In the Bothnia families, the previously detected associations with the 1.27 kb allele and haplotype 1.27-B10 were confirmed (P=0.01 and 0.02, respectively), whereas in the other families there was not even a trend toward association. These results demonstrate a geographic/genealogical restriction in the association between MS and the MBP short tandem repeat, highlight the importance of genealogical information in genetic studies of complex traits, and may provide an explanation why the association has not been found in many other populations.

Intercellular adhesion molecule-1 (ICAM-1) is involved in the pathogenesis of multiple sclerosis (MS), whereas sequence variations in the ICAM-1 gene could potentially be responsible for the genetic susceptibility to MS. We studied an association of MS with the 13,848A>G (K469E) polymorphism of the ICAM-1 gene in Finnish and Spanish cases and controls and affected families. An increased risk for the AA (Lys(469)/Lys(469)) genotype was found in both populations. The effect observed was found to be strongest among the HLA-DQB1*0602-positive subjects, which implies genetic heterogeneity of MS. Meta-analysis of all published datasets supports increased risk of MS for the ICAM-1 Lys(469) homozygotes (relative risk = 1.3, p = 0.002).