Factors Influencing Longitudinal Stair Climb Performance from Midlife to Early Late Life: The Study of Women's Health Across the Nation Chicago and Michigan Sites

OBJECTIVES

To quantify the longitudinal change in stair climb performance (a measure indicative of both physical function and muscle power), determine whether physical activity is related to slower decline in performance, and to identify factors that modify the longitudinal change in performance among women from midlife to late life.

DESIGN

Longitudinal cohort study with up to 15 study visits.

SETTING

Two sites of the Study of Women's Health Across the Nation.

PARTICIPANTS

Black (n=411) and white (N=419) women followed from median age 47.0 (44.6-49.6) to 62.0 (55.8-65.3) years.

INTERVENTIONS

N/A.

MEASUREMENTS

Performance on a stair climb test (ascend/descend 4 steps, 3 cycles) was timed. Physical activity (PA) was assessed using the Kaiser Physical Activity Survey (KPAS; possible range 0-15 points). Sociodemographic and health factors were assessed via self-report. BMI was calculated with measured height and weight. Mixed-effects regression modeled longitudinal change in stair climb performance.

RESULTS

Average baseline stair climb time was 18.12 seconds (95% CI: 17.83-18.41), with 0.98% (95% CI: 0.84%-1.11%) annual slowing. In fully adjusted models, higher levels of PA were associated with faster stair climb times (2.09% faster per point higher, 95% CI: -2.87%- -1.30%), and black women had 5.22% (95% CI: 2.43%-8.01%) slower performance compared to white women. Smoking, financial strain, diabetes, osteoarthritis, fair/poor health, and stroke were associated with 3.36% (95% CI: 0.07%-6.65%), 7.56% (95% CI: 4.75%-10.37%), 8.40% (95% CI: 2.89%-13.92%), 8.46% (95% CI: 5.12%-11.79%), 9.16% (95% CI: 4.72%-13.60%), and 16.94% (95% CI: 5.37%-28.51%) slower performance, respectively. In separate models, higher BMI (per 1-unit), osteoarthritis, fair/poor health, and diabetes, were each associated with 0.06% (95% CI:0.04%-0.08%), 0.48% (95% CI:0.12%-0.84%), 0.81% (95% CI:0.35%-1.28%), and 0.84% (95% CI:0.22%-1.46%), additional slowing per year over time.

CONCLUSION

Significant declines in function were evident as women transitioned from midlife to early late life. Declines were amplified by indicators of poor health, emphasizing the importance of health in midlife for promoting healthy aging.

Perceived helpfulness of the individual components of a behavioural weight loss program: results from the Hopkins POWER Trial

Background

Behavioural weight loss programs are effective first‐line treatments for obesity and are recommended by the US Preventive Services Task Force. Gaining an understanding of intervention components that are found helpful by different demographic groups can improve tailoring of weight loss programs. This paper examined the perceived helpfulness of different weight loss program components.

Methods

Participants (n = 236) from the active intervention conditions of the Practice‐based Opportunities for Weight Reduction (POWER) Hopkins Trial rated the helpfulness of 15 different components of a multicomponent behavioural weight loss program at 24‐month follow‐up. These ratings were examined in relation to demographic variables, treatment arm and weight loss success.

Results

The components most frequently identified as helpful were individual telephone sessions (88%), tracking weight online (81%) and coach review of tracking (81%). The component least frequently rated as helpful was the primary care providers' general involvement (50%). Groups such as older adults, Blacks and those with lower education levels more frequently reported intervention components as helpful compared with their counterparts.

Discussion

Weight loss coaching delivered telephonically with web support was well received. Findings support the use of remote behavioural interventions for a wide variety of individuals.

Patient-reported outcomes in the practice-based opportunities for weight reduction (POWER) trial

PURPOSE

To evaluate effects of two behavioral weight-loss interventions (in-person, remote) on health-related quality of life (HRQOL) compared to a control intervention.

METHODS

Four hundred and fifty-one obese US adults with at least one cardiovascular risk factor completed five measures of HRQOL and depression: MOS SF-12 physical component summary (PCS) and mental component summary; EuroQoL-5 dimensions single index and visual analog scale; PHQ-8 depression symptoms; and PSQI sleep quality scores at baseline and 6 and 24 months after randomization. Change in each outcome was analyzed using outcome-specific mixed-effects models controlling for participant demographic characteristics.

RESULTS

PCS-12 scores over 24 months improved more among participants in the in-person active intervention arm than among control arm participants (P < 0.05, ES = 0.21); there were no other statistically significant treatment arm differences in HRQOL change. Greater weight loss was associated with improvements in most outcomes (P < 0.05 to < 0.0001).

CONCLUSIONS

Participants in the in-person active intervention improved more in physical function HRQOL than participants in the control arm did. Greater weight loss during the study was associated with greater improvement in all PRO except for sleep quality, suggesting that weight loss is a key factor in improving HRQOL.

Regulation of plasmin-dependent fibrin clot lysis by annexin II heterotetramer

In a previous report we showed that plasmin-dependent lysis of a fibrin polymer, produced from purified components, was totally blocked if annexin II heterotetramer (AIIt) was present during fibrin polymer formation. Here, we show that AIIt inhibits fibrin clot lysis by stimulation of plasmin autodegradation, which results in a loss of plasmin activity. Furthermore, the C-terminal lysine residues of its p11 subunit play an essential role in the inhibition of fibrin clot lysis by AIIt. We also found that AIIt binds to fibrin with a K(d) of 436 nm and a stoichiometry of about 0.28 mol of AIIt/mol of fibrin monomer. The binding of AIIt to fibrin was not dependent on the C-terminal lysines of the p11 subunit. Furthermore, in the presence of plasminogen, the binding of AIIt to fibrin was increased to about 1.3 mol of AIIt/mol of fibrin monomer, suggesting that AIIt and plasminogen do not compete for identical sites on fibrin. Immunohistochemical identification of p36 and p11 subunits of AIIt in a pathological clot provides important evidence for its role as a physiological fibrinolytic regulator. These results suggest that AIIt may play a key role in the regulation of plasmin activity on the fibrin clot surface.

Fucoidan-dependent conformational changes in annexin II tetramer

Fucoidan, a sulfated fucopolysaccharide, mimics the fucosylated glycans of glycoproteins and has therefore been used as a probe for investigating the role of membrane polysaccharides in cell-cell adhesion. In the present report we have characterized the interaction of fucoidan with the Ca(2+)- and phospholipid-binding protein annexin II tetramer (AIIt). AIIt bound to fucoidan with an apparent K(d) of 1.24 +/- 0.69 nM (mean +/- SD, n = 3) with a stoichiometry of 0.010 +/- 0.001 mol of fucoidan/mol of AIIt (mean +/- SD, n = 3). The binding of fucoidan to AIIt was Ca(2+)-independent. Furthermore, in the presence but not the absence of Ca(2+), the binding of fucoidan to AIIt caused a decrease in the alpha-helical content from 32% to 7%. A peptide corresponding to a region of the p36 subunit of AIIt, F(306)-S(313), which contains a Cardin-Weintraub consensus sequence for heparin binding, was shown to undergo a conformational change upon fucoidan binding. This suggests that heparin and fucoidan bound to this region of AIIt. The binding of fucoidan but not heparin by AIIt also inhibited the ability of AIIt to bind to and aggregate phospholipid liposomes. These results suggest that the binding of AIIt to the carbohydrate conjugates of certain membrane glycoproteins may have profound effects on the structure and biological activity of AIIt.

Regulation of plasmin activity by annexin II tetramer

Annexin II tetramer (AIIt) is a major Ca(2+)-binding protein of the endothelial cell surface which has been shown to stimulate the tissue plasminogen activator (t-PA)-dependent conversion of plasminogen to plasmin. In the present report, we have examined the regulation of plasmin activity by AIIt. The incubation of plasmin with AIIt resulted in a 95% loss in plasmin activity. SDS-PAGE analysis established that AIIt stimulated the autoproteolytic digestion of plasmin heavy and light chains. The kinetics of AIIt-stimulated plasmin autoproteolysis were first-order, suggesting that binding of plasmin to AIIt resulted in the spontaneous autoproteolysis of the bound plasmin. AIIt did not affect the activity of other serine proteases such as t-PA or urokinase-type plasminogen activator. Furthermore, other annexins such as annexin I, II, V, or VI did not stimulate plasmin autoproteolysis. Increasing the concentration of AIIt on the surface of human 293 epithelial cells increased cell-mediated plasmin autoproteolysis. Thus, in addition to stimulating the formation of plasmin, AIIt also promotes plasmin inactivation. These results therefore suggest that AIIt may function to provide the cell surface with a transient pulse of plasmin activity.

Effect of estrogen agonists and antagonists on induction of progesterone receptor in a rat hypothalamic cell line

Estrogen is essential in the hypothalamus for the central regulation of reproduction. To understand the molecular mechanism(s) of estrogen action in the hypothalamus, immortalized rat embryonic hypothalamic cell lines were characterized for steroid receptors and subcloned. Scatchard analysis of the D12 subclone demonstrated one high affinity estrogen receptor-binding site (Kd = 31.3+/-1.9 pM) with a Bmax of 30.8+/-0.8 fmol/mg. Estrogen receptor-alpha protein was identified by Western blot and gel shift analyses. Treatment with estradiol (48 h) stimulated progesterone receptor (PR) messenger RNA expression and binding to [3H]R5020, a synthetic progestin. Because the agonist or antagonist activity of estrogen mimetics can be cell type dependent, the activities of various estrogen mimetics were determined in D12 cells. ICI 182,780 (IC50 = 0.63 nM), raloxifene (IC50 = 1 nM), enclomiphene (IC50 = 77 nM), and tamoxifen (IC50 = 174 nM) inhibited the induction of PR by estradiol, and none of these compounds significantly stimulated PR when given alone. In contrast, 17alpha-ethynyl estradiol (EC50 = 0.014 nM), zuclomiphene (EC50 = 100 nM), and genistein (EC50 = 17.5 nM) functioned as estrogen agonists in these cells. In addition, the estrogen-induced progesterone receptor activated a progesterone response element reporter construct in response to progestins. Thus, the D12 rat hypothalamic cell line provides a useful model for characterizing tissue-selective estrogenic compounds, identifying estrogen- and progesterone-regulated hypothalamic genes, and understanding the molecular mechanisms of steroid action in various physiological processes mediated by the hypothalamus.

Expression of estrogen receptor-beta protein in rodent ovary

Estrogen is an essential hormone for the LH surge and ovulation. The primary source of estrogen is from ovarian granulosa cells and in rats, estrogen, in turn, increases granulosa cell number and enhances FSH-stimulated gene expression in these cells. Thus, rat granulosa cells both respond to and synthesize estrogen. To further elucidate the mechanisms mediating the actions of estrogen in granulosa cells, we have identified and characterized the estrogen receptor-beta (ER-beta) subtype in rodent granulosa cells. ER-beta protein was localized to the nuclei of rat granulosa cells in preantral and antral follicles by immunocytochemistry, coincident with the location of ER-beta messenger RNA (mRNA). Immunoprecipitation and Western blot analysis using ER-beta specific antisera demonstrated a protein of approximately 60 kDa in granulosa cells prepared from PMSG-primed immature mice and estrogen-treated immature rats. Extracts from granulosa cells specifically bound an estrogen response element and the complex was recognized by antisera to ER-beta. A synthetic steroid estrogen radioligand, [125I]-17alpha-iodovinyl-11beta-methoxyestradiol ([125I]-VME2), bound to cytosolic granulosa cell preparations with high affinity (estimated K(D) value of 401 +/- 83 pM, and Bmax value of 102 +/- 9 fmol/mg protein). ER-beta protein levels rapidly declined following hCG treatment consistent with the reported decrease in binding activity and ER-beta mRNA levels by high levels of gonadotropins. Overall, we have demonstrated that 1) ER-beta protein is the dominant estrogen receptor subtype present in rodent granulosa cells, 2) this receptor is functional, and 3) it is regulated by ovulatory doses of gonadotropins. Thus, ER-beta is likely to be a mediator of estrogen action in rodent granulosa cells during follicular development.

Role of annexin II tetramer in plasminogen activation

The enzymatic cascade triggered by activation of plasminogen has been implicated in a variety of normal and pathologic events, such as fibrinolysis, wound healing, tissue remodeling, embryogenesis, and the invasion and spread of transformed tumor cells. Recent data established that the Ca(2+)- and phospholipid-binding protein, annexin II heterotetramer (AIIt) binds tissue-type plasminogen activator (tPA), plasminogen, and plasmin, and dramatically stimulates the tPA-dependent conversion of plasminogen to plasmin in vitro. Interestingly, the binding of plasmin to AIIt can inhibit the activity of the enzyme, suggesting that plasmin bound to the cell surface is regulated by AIIt. The existing experimental evidence suggests that AIIt is the key physiological receptor for plasminogen on the extracellular surface of endothelial cells.

The p11 subunit of the annexin II tetramer plays a key role in the stimulation of t-PA-dependent plasminogen activation

Annexin II tetramer (AIIt) is an important endothelial cell surface protein receptor for plasminogen and t-PA. AIIt, a heterotetramer, is composed of two p36 subunits (called annexin II) and two p11 subunits. In this report, we have compared the ability of the isolated p36 and p11 subunits to stimulate t-PA-dependent [Glu]plasminogen activation. The fluid-phase recombinant p11 subunit stimulated the rate of t-PA-dependent activation of [Glu]plasminogen about 46-fold compared to an approximate stimulation of 2-fold by the recombinant p36 subunit and 77-fold by recombinant AIIt. The stimulation of t-PA-dependent activation of [Glu]plasminogen by the p11 subunit was Ca2+-independent and inhibited by epsilon-aminocaproic acid. [Glu]Plasminogen bound to a p11 subunit affinity column and could be eluted with epsilon-aminocaproic acid. Both AIIt and the p11 subunit protected t-PA and plasmin from inactivation by PAI-1 and alpha2-antiplasmin, respectively. A peptide to the C terminus of the p11 subunit (85-Y-F-V-V-H-M-K-Q-K-G-K-K-96) inhibited the p11-dependent stimulation of t-PA-dependent plasminogen activation. In addition, a deletion mutant of the p11 subunit, missing the last two C-terminal lysine residues, retained only about 15% of the activity of the wild-type p11 subunit. Similarly, a mutant AIIt composed of the wild-type p36 subunit and the p11 subunit deletion mutant possessed about 12% of the wild-type activity. These results, therefore, suggest that the C-terminal lysine residues of the p11 subunit bind plasminogen and participate in the stimulation of t-PA-dependent activation of plasminogen by AIIt.

Expression of growth differentiation factor-9 messenger ribonucleic acid in ovarian and nonovarian rodent and human tissues

Growth differentiation factor-9 (GDF-9) is a member of the transforming growth factor-beta family that is reported to be expressed exclusively in the ovary, specifically in the oocyte. Female mice deficient in GDF-9 are infertile, suggesting that GDF-9 receptor agonists and antagonists may specifically modulate fertility. We now report that GDF-9 messenger RNA (mRNA) is expressed in nonovarian tissues in mice, rats, and humans. GDF-9 mRNA was detected in mouse and rat ovary, testis, and hypothalamus by Northern blot and RT-PCR analyses. The localization of GDF-9 mRNA specifically in oocytes of the mouse ovary was confirmed by in situ hybridization histochemistry. In mouse testis, although localization in Sertoli cell cytoplasm could not be ruled out, mRNA expression was observed in large pachytene spermatocytes and round spermatids. The expression of GDF-9 mRNA in human tissues was assessed by Northern blot and RT-PCR analyses. GDF-9 mRNA was observed in ovary and testis and, surprisingly, in diverse nongonadal tissues, including pituitary, uterus, and bone marrow. Therefore, GDF-9 mRNA expression in rodents is not exclusive to the ovary, but includes the testis and hypothalamus. Furthermore, human GDF-9 mRNA is expressed not only in the gonads, but also in several extragonadal tissues. The function and relevance of nongonadal GDF-9 mRNA are not known, but may affect strategies for contraception and fertility that are based on GDF-9 activity.

The role of annexin II tetramer in the activation of plasminogen

Annexin II tetramer (AIIt) is a major Ca2+-binding protein of endothelial cells which has been shown to exist on both the intracellular and extracellular surfaces of the plasma membrane. In this report, we demonstrate that AIIt stimulates the activation of plasminogen by facilitating the tissue plasminogen activator (t-PA)-dependent conversion of plasminogen to plasmin. Fluid-phase AIIt stimulated the rate of activation of [Glu]plasminogen about 341-fold compared with an approximate 6-fold stimulation by annexin II. AIIt bound to [Glu]plasminogen(S741C-fluorescein) with a Kd of 1. 26 +/- 0.04 microM (mean +/- S.D., n = 3) and this interaction resulted in a large conformational change in [Glu]plasminogen. Kinetic analysis established that AIIt produces a large increase of about 190-fold in the kcat, app and a small increase in the Km,app which resulted in a 90-fold increase in the catalytic efficiency (kcat/Km) of t-PA for [Glu]plasminogen. AIIt also stimulated the t-PA-dependent activation of [Lys]plasminogen about 28-fold. Furthermore, other annexins such as annexin I, V, or VI did not produce comparable activation of t-PA-dependent conversion of [Glu]plasminogen to plasmin. The stimulation of the activation of [Glu]plasminogen by AIIt was Ca2+-independent and inhibited by epsilon-aminocaproic acid. AIIt bound to human 293 cells potentiated t-PA-dependent plasminogen activation. AIIt that was bound to phospholipid vesicles or heparin also stimulated the activation of [Glu]plasminogen 5- or 11-fold, respectively. Furthermore, immunofluorescence labeling of nonpermeabilized HUVEC revealed a punctated distribution of AIIt subunits on the cell surface. These results therefore identify AIIt as a potent in vitro activator of plasminogen.

Annexin II tetramer inhibits plasmin-dependent fibrinolysis

In this paper, we have characterized the regulation of plasmin activity by annexin II tetramer (AIIt). Plasmin activity was measured by a fibrin lysis assay in which a fibrin polymer was produced from purified components and the extent of polymer lysis was determined by following changes in turbidity. Extrinsic lysis of the fibrin polymer, initiated by addition of tissue plasminogen activator (t-PA), was totally blocked if AIIt was present during fibrin polymer formation. Furthermore, fibrin polymer formed in the presence of AIIt was resistant to extrinsic lysis initiated by addition of plasmin. AIIt bound to fibrin polymer under conditions in which polymer lysis was inhibited. Plasmin-dependent extrinsic lysis of the fibrin polymer was also blocked if AIIt was present in the incubation medium, and under these conditions the amidolytic activity of plasmin, measured with an artificial substrate, was inhibited about 5-fold. In contrast, in the absence of fibrin, and at an AIIt/plasmin molar ratio of 526, the amidolytic activity of plasmin was inhibited by only 22.3% +/- 7.4% (mean +/- SD, n = 5) by AIIt. Plasmin-dependent fibrinolysis was only slightly inhibited if fibrin polymer was formed in the presence of annexins I, II, V, or VI. These results identify AIIt as an in vitro regulator of plasmin activity.

Characterization of the heparin binding properties of annexin II tetramer

In this report, we have characterized the interaction of heparin with the Ca2+- and phospholipid-binding protein annexin II tetramer (AIIt). Analysis of the circular dichroism spectra demonstrated that the Ca2+-dependent binding of AIIt to heparin caused a large decrease in the alpha-helical content of AIIt from approximately 44 to 31%, a small decrease in the beta-sheet content from approximately 27 to 24%, and an increase in the unordered structure from 20 to 29%. The binding of heparin also decreased the Ca2+ concentration required for a half-maximal conformational change in AIIt from 360 to 84 microM. AIIt bound to heparin with an apparent Kd of 32 +/- 6 nM (mean +/- S.D., n = 3) and a stoichiometry of 11 +/- 0.9 mol of AIIt/mol of heparin (mean +/- S.D., n = 3). The binding of heparin to AIIt was specific as other sulfated polysaccharides did not elicit a conformational change in AIIt. A region of the p36 subunit of AIIt (Phe306-Ser313) was found to contain a Cardin-Weintraub consensus sequence for glycosaminoglycan recognition. A peptide to this region underwent a conformational change upon heparin binding. Other annexins contained the Cardin-Weintraub consensus sequence, but did not undergo a substantial conformational change upon heparin binding.

Characterization of human recombinant annexin II tetramer purified from bacteria: role of N-terminal acetylation

Annexin II tetramer (AIIt) is a Ca2+-dependent, phosphatidylserine-binding, and F-actin-bundling phosphoprotein which is localized to both the extracellular and cytoplasmic surfaces of the plasma membrane. The tetramer is composed of two p36 heavy chains and two p11 light chains. We have produced prokaryotic cDNA expression constructs for both p36 and p11. Both proteins were expressed in large amounts in Escherichia coli upon induction with IPTG. Electrospray ionization mass spectrometry and amino acid sequence analysis of purified recombinant p36 (rp36) and recombinant p11 (rp11) suggested that the recombinant proteins were identical to their native counterparts except for the lack of N-terminal acetylation of rp36. Furthermore, the non-acetylated rp36 bound rp11 and formed AIIt. The circular dichroism spectra and urea denaturation profiles of acetylated AIIt and non-acetylated rAIIt were identical. In addition, both the acetylated AIIt and non-acetylated rAIIt were similar in their Ca2+ dependence and concentration dependence of phospholipid liposome aggregation, chromaffin granule aggregation, and F-actin bundling. These results suggest that N-terminal acetylation of p36 is not in fact necessary for binding of the protein to p11 and that N-terminal acetylation does not affect the conformational stability of AIIt or the in vitro activities of AIIt. The availability of large amounts of rAIIt will facilitate further characterization of the structure-function relationships of the protein.

Tyrosine phosphorylation of annexin II tetramer is stimulated by membrane binding

In the present article we have examined if the interaction of the Ca2+-binding protein, annexin II tetramer (AIIt) with the plasma membrane phospholipids or with the submembranous cytoskeleton, effects the accessibility of the tyrosine phosphorylation site of AIIt. In the presence of Ca2+, pp60(c-src) catalyzed the incorporation of 0.22 +/- 0.05 mol of phosphate/mol of AIIt (mean +/- S.D., n = 5). The Ca2+-dependent binding of AIIt to purified adrenal medulla plasma membrane or phosphatidylserine vesicles stimulated the pp60(c-src)-dependent phosphorylation of AIIt to 0.62 +/- 0.04 mol of phosphate/mol of AIIt (mean +/- S.D., n = 5) or 0.93 +/- 0.07 mol of phosphate/mol of AIIt (mean +/- S.D., n = 5), respectively. Phosphatidylserine- or phosphatidylinositol-containing vesicles but not vesicles composed of phosphatidylcholine or phosphatidylethanolamine, stimulated the phosphorylation of AIIt. In contrast, the binding of AIIt to F-actin resulted in the incorporation of only 0.04 +/- 0.04 mol of phosphate/mol of AIIt (mean +/- S.D., n = 5). These results suggest that the interaction of AIIt with plasma membrane and not the submembranous cytoskeleton, activates the tyrosine phosphorylation of AIIt by inducing a conformational change in the protein resulting in the enhanced exposure or accessibility of the tyrosine-phosphorylation site.

Expression of aromatase in the ovary: down-regulation of mRNA by the ovulatory luteinizing hormone surge

Aromatase (CYP19) mRNA is induced by follicle-stimulating hormone (FSH) in granulosa cells of preovulatory follicles and subsequently is rapidly diminished as a consequence of the luteinizing hormone (LH) surge. Primary cultures of rat granulosa cells were used to identify some of the cellular mechanisms by which FSH increases and LH decreases steady-state levels of aromatase mRNA. Induction of aromatase mRNA by FSH was increased by cycloheximide but was blocked by alpha-amanitin and the C-kinase activators gonadotropin-releasing hormone (GnRH) and phorbol 12-myristate 13-acetate (PMA). In contrast, the decrease in steady-state levels of aromatase mRNA by LH was mimicked by A-kinase (forskolin) and C-kinase (PMA or GnRH) activators. The decrease in aromatase mRNA was associated with decreased amounts of mRNA and protein for steroidogenic factor-1 (SF-1), a nuclear orphan receptor that binds and trans-activates the aromatase promoter, and with the A-kinase subunit type II (RII beta), which is required for mediating cAMP action in these cells. The down-regulation of aromatase, SF-1, and RII beta by each kinase activator and alpha-amanitin was prevented by cycloheximide when the drug was added in combination with the activator. If, however, cycloheximide was added 2 h after PMA (or LH), the drug did not prevent the rapid loss of mRNA. When granulosa cells were transfected with an aromatase CAT transgene, CAT activity was stimulated 10- to 20-fold by FSH and forskolin but not by PMA. Taken together, these results indicate that the A-kinase but not the C-kinase pathway can trans-activate the aromatase gene in immature granulosa cells, whereas the C-kinase, as well as A-kinase pathways, mimic the LH surge to decrease aromatase mRNA in preovulatory cells. By increasing degradation of aromatase mRNA and by inhibiting transcription, the LH surge rapidly terminates the granulosa cell pattern of gene expression while reprogramming the cells to express genes associated with ovulation and luteinization.

Ovarian cell differentiation: a cascade of multiple hormones, cellular signals, and regulated genes

During the development of preovulatory follicles, tonic levels of FSH (and steroid) induce expression of aromatase, the LH receptor, and RII beta in a coordinate manner. Despite the similar temporal increase in steady-state levels of mRNA encoding these proteins, the cis-acting DNA elements and trans-acting factors regulating each gene are distinct (Richards, 1993). Whereas the aromatase gene has a TATA motif and a single transcriptional initiation site (Fitzpatrick and Richards, 1993), both the LH receptor (Wang et al., 1992; Tsai-Morris et al., 1993) and RII beta (Kurten et al., 1992; Luo et al., 1992) genes have promoters that are GC rich, lack TATA motifs, and initiate transcription at multiple sites. The aromatase promoter appears to be regulated, in part, by SF-1, a CRE-like region, and possibly another or overlapping region binding an Ad3BP-like factor. The RII beta promoter has a region that binds several nuclear proteins, whose identity is not yet known. Likewise, the LH receptor promoter elements have yet to be clearly defined (Figures 2, 4, and 25; Kurten et al., 1992). FSH can also induce the expression of at least three immediate-early genes that encode novel kinases or kinase-like proteins (Figure 25). One of these is called serum-inducible kinase (snk) (Simmons et al., 1992), another is serum and glucocorticoid regulated kinase (sgk) (Webster et al., 1993), and a third is called pole kinase (Clay et al., 1993). Steady-state levels of snk and sgk mRNA are induced rapidly (within a few hours) by FSH in granulosa cells prior to the appearance of transcripts for aromatase, LH receptor, and RII beta (T. Alliston and J. S. Richards, in preparation). The functional role of these kinases in the initial response of granulosa cells to tonic (not surge) levels of FSH remains to be elucidated. The cellular signaling pathways mediating the effects of the LH surge appear equally or more complex (Fig. 25). Based on data presented herein, as well as on analyses of the cloned and expressed LH receptor (Guderman et al., 1992), it is clear that low concentrations of LH stimulate adenylyl cyclase, cAMP production, and activation of protein kinase A. Higher (surge) concentrations of LH also increase IP3 and activation of protein kinase C. GnRH has been used in several studies to examine the ability of the protein kinase C pathway to mimic effects of high LH.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of a cyclic adenosine 3',5'-monophosphate-response element in the rat aromatase promoter that is required for transcriptional activation in rat granulosa cells and R2C leydig cells

Cytochrome P450 aromatase, which converts testosterone to estradiol, is transcriptionally induced by FSH and cAMP during ovarian follicular development. At least one promoter element [-82/-31 base pairs (bp)] required for stimulation of the rat gene in granulosa cells binds steroidogenic factor-1, an orphan steroid receptor. In this paper, we demonstrate that an additional region, -161/-138 bp is required for cAMP regulation. This region shares homology with promoter sequences in the bovine 21-hydroxylase and mouse 11 beta-hydroxylase genes that are also induced by cAMP, yet each binds different proteins in granulosa cell nuclear extracts. The aromatase -161/-138 bp region contains a cAMP-response element (CRE)-like sequence, TGCACGTCA. Deletion or mutation of this sequence reduces promoter activity of chimeric chloramphenicol acetyl transferase (CAT) reporter constructs that are transiently transfected into granulosa cells and R2C Leydig cells. Granulosa cell nuclear proteins and R2C cell nuclear proteins specifically bind the -161/-138 bp region and form three protein/DNA complexes. Recombinant CRE-binding protein (CREB) binds the CRE-like sequence and forms a single band, and a CREB antibody retards the migration of CREB and one granulosa cell protein-aromatase DNA binding complex. Using Western blot analysis, CREB was demonstrated in granulosa cell nuclear extracts from all stages of follicular development. Thus, aromatase is transcriptionally regulated by a hexameric sequence binding SF-1 and a CRE sequence binding CREB and other factors present in granulosa cells and in R2C Leydig cells. The presence of identical SF-1 and CRE-like sequences in the human ovarian aromatase promoter II suggests that the human promoter may also be regulated in a similar manner.

cis-acting elements of the rat aromatase promoter required for cyclic adenosine 3',5'-monophosphate induction in ovarian granulosa cells and constitutive expression in R2C Leydig cells

The cytochrome P450 aromatase gene is transcriptionally regulated by FSH and steroids in granulosa cells of developing ovarian follicles. To characterize the molecular mechanisms by which this regulation occurs, the promoter of the rat aromatase gene has been analyzed by 1) mapping the transcriptional start site, 2) constructing deletion mutant reporter genes for transfection assays, and 3) determining DNA-protein interactions by gel shift assays. Transient transfection assays indicated that promoter sequences between -176 and -31 basepairs (bp) were required for cAMP inducibility of reporter constructs in primary cultures of granulosa cells and for expression in rat R2C Leydig cells, which constitutively express high amounts of aromatase mRNA. Nuclear extract proteins from granulosa cells and R2C Leydig cells specifically bound a labeled -176/13-bp fragment and were competed by cold competitor fragment as well as by a shorter region (-90/-66 bp) containing an AGGTCA hexameric motif. Competition was inhibited by mutation of the central GGs and was affected by adjacent 5' contextual sequences. A possible candidate for the binding activity observed in granulosa cells and R2C cell nuclear extracts binds an oligonucleotide containing the aromatase AGGTCA motif and is an orphan member of the steroid/thyroid hormone superfamily. These results are the first to characterize cis-acting DNA elements in the aromatase promoter, identify a region that confers cAMP inducibility in granulosa cells and constitutive expression in R2C cells, and localize a hexameric sequence within this region that binds at least one member of the orphan receptor class of transcription factors.

Regulation of the rat aromatase gene in ovarian granulosa cells and R2C Leydig cells

Aromatase cytochrome P450 is regulated in granulosa cells of ovarian follicles by the synergistic action of FSH and steroids. The effect of FSH can be mimicked by forskolin suggesting that transcription of the aromatase gene is regulated by cAMP. In contrast, aromatase is constitutively expressed in the rat R2C Leydig cells. To characterize the functional regions of the promoter in these two cell types, a fragment containing 534 bp of the aromatase promoter sequence and various deletion mutants were ligated to a reporter gene, chloramphenicol acetyl transferase and used in transient transfection assays. The results suggest that the region between -176 and -31 bp is essential both for cAMP regulation in granulosa cells and constitutive expression in R2C cells. Nuclear proteins from granulosa and R2C cells specifically bind the -176 fragment in an electrophoretic mobility shift assay. Binding was completed by an oligonucleotide (-90/-66 bp) containing a hexameric sequence, AGGTCA, which has been found in the promoters of other steroidogenic genes. These results suggest that cAMP regulation and constitutive expression of the rat aromatase promoter requires sequences between -176 and -31 bp, particularly the sequence AGGTCA at -82/.-77 and nuclear proteins binding to these sequences.

3-Hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors. 9. The synthesis and biological evaluation of novel simvastatin analogs

Substitution of hydroxy and hydroxyalkyl functionality at C-7 of the hexahydronaphthalene nucleus of simvastatin has provided novel analogs. The synthetic strategy employed epoxidation or Lewis acid-catalyzed aldol reaction of the 8-keto silyl enol ether as a key reactive intermediate. These analogs were evaluated as potential hypocholesterolemic agents via initial determination of their ability to inhibit HMG-CoA reductase in vitro. Oral activity of these compounds was determined in an acute rat model and a three-week study in cholestyramine-primed dogs. Compounds were identified that possessed in vitro and in vivo activity comparable to that of simvastatin.

The human placental lactogen genes: structure, function, evolution and transcriptional regulation

hPL is a member of an evolutionarily related gene family including hGH and hPRL. Expression of hPL is limited to the placenta but its physiological actions are far reaching. hPL has a direct somatotropic effect on fetal tissues, it alters maternal carbohydrate and lipid metabolism to provide for fetal nutrient requirements, and aids in stimulation of mammary cell proliferation. Two hPL genes (hPL3 and hPL4) encoding identical proteins are responsible for the production of up to 1-3 g PL hormone/day. Recent studies have characterized the regulatory controls of hPL expression. At the post transcriptional level, RNA stability may contribute to variable levels of hPL3 vs. hPL4 production. In addition, non-tissue-specific protein-promoter interactions involving the Sp1 transcription factor are necessary for hPL transcription initiation. A transcriptional enhancer located 3' to the hPL3 gene is responsible for the placenta-specific expression of this gene, while an additional enhancer may be located 3' to the hPl4 gene. The hPL enhancer is bound by multiple proteins including at least one placental specific protein that interacts with a TEF-1 motif. Therefore, enhancer-protein interactions most likely play a large part in the high levels of placenta-specific hPL expression.

Regulation of cytochrome P450 aromatase messenger ribonucleic acid and activity by steroids and gonadotropins in rat granulosa cells

Estradiol (E) biosynthesis by the cytochrome P450 aromatase (P450arom) enzyme system increases as preovulatory follicles develop and is subsequently reduced by the ovulatory LH surge. To determine the specific effects of gonadotropins and steroids on expression of P450arom in rat granulosa cells, steady state levels of messenger (m) RNA were examined in vivo and in vitro, with the latter also being related to aromatase enzyme activity and cAMP production. P450arom mRNA and activity were induced in granulosa cells by FSH alone in a dose-, time-, and stage-dependent manner. E enhanced the effects of FSH in vivo and in vitro. The synergistic effect of E with FSH (50 ng/ml) was observed in the absence/presence of serum and was mimicked by a similar concentration (20 nM) of testosterone, dihydrotestosterone, or dexamethasone. In contrast, ovulatory doses of LH (500 ng/ml) or forskolin (10 microM) but not concentrations of progesterone reached in preovulatory follicles (100-1000 nM) acted on differentiated (FSH + E) granulosa cells to cause a rapid loss of P450arom mRNA. Whereas cycloheximide prevented the LH/cAMP-mediated decrease in P450arom mRNA in the differentiated cells, enzyme activity remained unaltered during the same 6-h period. Thus, expression of aromatase mRNA in rat granulosa cells is induced primarily by low FSH/cAMP, enhanced by physiological doses of several steroids (except progesterone), and, once induced, can be rapidly inhibited by elevated gonadotropin/cAMP via a pathway requiring protein synthesis.

DNA sequences involved in the transcriptional activation of a human placental lactogen gene

To identify regulatory elements in the promoter of a human placental lactogen gene (hPL3) that are important for its transcriptional activation, sequences 5' to the start of transcription were linked to the reporter gene chloramphenicol acetyltransferase (CAT) and transiently transfected into JEG-3 cells, a human placental choriocarcinoma cell line. In the presence of the hPL3 enhancer, deletion of the promoter sequence between -142 and -129 basepairs resulted in an 8-fold decrease in CAT activity. Similar results were seen with the SV40 enhancer and the hPL3 promoter in HepG2 liver cells. Nuclear proteins from HepG2, HeLa, and JEG-3 cells formed specific binding complexes with this region of the hPL3 promoter by a gel mobility shift assay, indicating that the DNA-binding protein was not tissue specific. The -142 to -129 basepair region contains a sequence similar to that of a variant binding site for the transcription factor Sp1. An oligonucleotide containing Sp1-binding sites specifically competes for proteins binding the hPL3 promoter, and the methylation interference pattern is similar to that for an Sp1-binding site. This suggests that the hPL3 promoter binds Sp1- or an Sp1-like trans-acting factor, and this binding site is important for transcriptional regulation by the hPL3 enhancer in PL-producing cells.

Human placental lactogen transcriptional enhancer. Tissue specificity and binding with specific proteins

Human placental lactogen (hPL) and growth hormone (hGH) are thought to be derived from a common ancestral gene and have similar nucleotide and amino acid sequences. Although the genes are similar in structure, they are expressed in different tissues. A transcriptional enhancer has been found 2.2 kilobases 3' of the hPL3 gene at the distal extreme of the hPL/hGH gene cluster. This enhancer is at least 20-fold more active in hPL-producing human choriocarcinoma JEG-3 cells than in non-hPL-producing cells. The enhancer is active when linked to either the hPL3 or SV40 promoter. We have localized the hPL enhancer to a 138-base pair (bp) region that retains tissue specificity in transient transfection assays. Gel mobility shift assays showed that the hPL enhancer interacted specifically with nuclear proteins from JEG-3 cells and placental tissue. Within the 138-bp enhancer, a 22-bp region overlapping a TEF-1 binding site was shown to be protected from DNase I digestion by placental and HeLa nuclear extracts. Placental protein(s) binding this region may be instrumental in tissue-specific activity of the hPL enhancer.

Epidermal growth factor binding by breast tumor biopsies and relationship to estrogen receptor and progestin receptor levels

Epidermal growth factor (EGF) may be important in regulating the growth of some breast cancer cells in vivo because of its mitogenic action on some breast cancer cell lines in vitro. Epidermal growth factor receptors (EGF-R) were measured in a series of breast tumors to determine what percentage of breast tumors express EGF-R and whether EGF-R was independent of expression of estrogen receptor and progestin receptor. Specific binding of 125I-EGF to membranes from pooled homogenates of breast tumors reached equilibrium after 45 min at 25 degrees and remained constant. Scatchard analysis of 125I-EGF binding indicated a single class of receptors with an apparent Kd of 2 nM and a binding capacity of 28 fmol/mg of membrane protein, and the binding of 125I-EGF was not effectively competed for by insulin, fibroblast growth factor, growth hormone, or prolactin. Specific binding of 125I-EGF of 1 fmol or greater/mg of membrane protein and 15% or greater specific binding was detected in 48% of 137 unselected primary and metastatic breast tumors. The frequency distribution of EGF binding values was unimodal, with a progressive decrease in the proportion of patients with high EGF binding values. The values of EGF binding ranged from 1 to 121 fmol/mg of protein, with an arithmetic mean of 8.4 fmol/mg of protein and a geometric mean of 3.2 fmol/mg of protein. Forty-two % of 24 metastatic breast tumors were positive for EGF binding, with an arithmetic mean of 6.3 fmol/mg of protein and a geometric mean of 4.1 fmol/mg of protein. The magnitude of EGF binding in individual tumors was independent of either estrogen receptor or progestin receptor levels, although the highest quantities of EGF binding were expressed by tumors lacking steroid receptors. Approximately 20% of the tumors in the study were EGF-R-positive and ER-negative, suggesting that the growth of these tumors may be regulated predominantly by a peptide hormone (EGF) rather than a steroid hormone (estrogen). EGF binding did not correlate significantly with age of the patients. Correlation analysis between EGF binding and the percentage of malignant and nonmalignant cell types present in sections of tumor adjacent to the area assayed for EGF binding indicated that the percentage of malignant cells is an important factor in determining the amount of EGF binding in tumor homogenates. The recent discovery of transforming growth factors which interact with the EGF-receptor system suggests additional roles for EGF receptors in breast cancer.

Characterization of epidermal growth factor receptor and action on human breast cancer cells in culture

Epidermal growth factor (EGF) may play a role in regulating growth of breast cancer cells in vivo. We have examined the action of EGF on breast cancer cells in vitro and characterized the EGF receptor as a model system for its action in vivo. All of the fourteen breast cancer cell lines which grow attached to culture dishes specifically bound EGF, including one purportedly normal breast line (HBL-100). The one cell line examined which grows as a suspension, DU-4475, did not express measurable levels of EGF binding. The number of EGF binding sites per cell for the different cell lines varied from 200 EGF binding sites/cell (for MDA-MB-436) to 700,000 EGF binding sites/cell (for MDA-MB-231), with most cell lines having approximately 10,000 EGF binding sites/cell. Scatchard analysis of EGF binding to four of the breast cell lines indicated a single class of high-affinity binding sites for MDA-MB-231 cells (Kd = 200 pM; n = 220 fmol of EGF bound/mg of cell protein); and for T-47D cells (Kd = 4 nM, n = 85 fmol of EGF bound/mg of cell protein) and curvilinear plots for MCF-7 cells and HBL-100 cells. The EGF binding to MDA-MB-231 cells was specific for EGF and was maximum after 2 hr at 37 degrees, followed by a progressive loss of cell-associated radio-activity, which was prevented by the action of the lysosomal inhibitory agent chloroquine. Specific covalent binding of 125I-EGF to MDA-MB-231 cells indicated that the EGF receptor had molecular weights of 165,000 and 140,000. MCF-7 cells and T-47D cells grown in serum-free medium supplemented with 10 nM EGF for 3 days had significantly increased protein, DNA, and cell number, whereas MDA-MB-231 and ZR-75-1 cells did not respond significantly to EGF. These results indicate that EGF receptors are consistently expressed by breast cells grown attached to a surface but that some cell lines expressing EGF receptors do not respond mitogenically to EGF. The biochemical characteristics of EGF receptors in MDA-MD-231 breast cells are similar to those observed for EGF receptors in other human tissues.