Ca(2+)-dependent regulation of the Ca(2+) concentration in the myometrium mitochondria. I. Trifluoperazine effects on mitochondria membranes polarization and [Ca(2+)](m)

Са2+-dependent regulation of Ca2+ exchange in mitochondria is carried out with participation of calmodulin. We have shown previously that calmodulin antagonists reduced the level of mitochondrial membrane polarization and induced increase of the ionized Са concentration in both the mitochondrial matrix and cell cytoplasm. The concentration-dependent influence of trifluoperazine on the level of polarization of mitochondrial membranes has been shown in this work. The coordinates of the Hill graphs were used to calculate the constant K0.5 and the Hill coefficient. K0.5 was 24.4 ± 5 μM (n = 10). The Hill coefficient was 2.0 ± 0.2, indicating the presence of two centers of the trifluoperazine binding. We have also studied [Ca2+]m changes, when incubating mitochondria in mediums of different composition: without ATP and ions of Mg (0-medium), in the presence of 3 mM Mg (Mg-medium) and 3 mM Mg + 3 mM ATP (Mg,ATP-medium). It was shown that the composition of the incubation medium affected the [Ca2+]m values in the absence of exogenous Ca2+ and did not affect them in the presence of the latter. Preincubation of mitochondria in mediums of different composition with 25 μM trifluoperazine did not affect the [Ca2+]m values both before and after the addition of 100 µМ Са2+ to the incubation medium. It was concluded, that trifluoperazine depolarized myometrial mitochondria membranes in concentration-dependent manner. However, mitochondria preincubation with 25 μM trifluope­razine accompanied by 50% decrease in membrane polarization did not affect the [Ca2+]m values.

Calix[4]arene C-90 and its analogs activate ATPase of the myometrium myosin subfragment-1

Numerous female reproductive abnormalities are consequences of disorders in uterus smooth muscle (myometrium) contractile function. In this work, we described activators of ATPase, which could be used for development of effective treatments for correcting this dysfunction. Myosin ATPase localized in the catalytic domain of myosin subfragment-1 transforms a chemical energy deposited in macroergic bonds of ATP into mechanical movement. It was shown that сalix[4]arene C-90 and its structural analogs functionalized at the upper rim of macrocycle with four or at least two N-phenylsulfonуltrifluoroacetamidine groups, are able to activate ATP hydrolysis catalyzed by myometrium myosin subfragment-1. It was shown with the method of computer modeling that N-phenylsulfonуltrifluoroacetamidine groups of calix[4]arene C-90 interact with responsible for binding, coordination and the hydrolysis of ATP amino acid residues of myosin subfragment-1. The results can be used for further research aimed at using calix[4]arene C-90 and its analogs as pharmacological compounds that can effectively normalize myometrium contractile hypofunction.

Prolactin role in the bovine uterus during adenomyosis

Adenomyosis is uterine dysfunction defined as the presence of endometrial glands within the myometrium. It is suggested that adenomyosis is estrogen-dependent pathology, and prolactin (PRL) also affects its development. In the uterus of ruminants, PRL stimulates gland proliferation and function. We hypothesized that in the bovine uterus, the expression of PRL and its receptors (PRLRs) during adenomyosis is disturbed and modulated by estradiol (E₂). Uterine tissues were collected postmortem from cows; epithelial, stromal, and myometrial cells were isolated; and cultured and treated with E₂. Material was divided into 2 groups: control (nonadenomyotic) and uteri with adenomyosis. In adenomyotic uterine tissue, PRL and its long-form receptor protein were increased, as determined by Western blotting. Immunohistostaining showed that during adenomyosis, PRL and its receptors are highly expressed in adenomyotic lesions. In cultured myometrial cells, protein expression of PRL and its receptors was increased during adenomyosis. Estradiol decreased PRLRs protein expression in nonadenomyotic stromal cells and in adenomyotic myometrial cells, and increased PRL secretion by adenomyotic myometrial cells. Moreover, PRL secretion was increased in untreated epithelial and stromal cells during adenomyosis. On the other hand, in stromal cells, PRLRs messenger RNA and protein expression was decreased, as determined by real-time PCR and Western blotting, respectively. Obtained results show that significant changes in PRL and PRLRs expression are observed in uterine tissue and cells during adenomyosis, which were also affected by E₂. These data suggest involvement of PRL in adenomyosis development and the link between PRL and E₂ actions during the dysfunction in cows.

Progesterone Receptor or Cytoskeletal Protein?

Immunoblotting is used to characterize the various nuclear progesterone receptor (nPR) isoforms present in tissues; however, the success of this technique is dependent on the specificity of the primary nPR antibody. The authors investigate the specificity of a frequently used nPR antibody, sc-538, in total protein from human myometrium and a myometrial cell line (PHM1-31). Using immunoblotting, 2 sc-538 immunoreactive bands at 100 and 55 kDa were detected. The bands were extracted and identified by 1-dimensional liquid chromatography mass spectrometry. The predominant protein in the 100-kDa band was alpha-actinin. The dominant proteins in the smaller band were vimentin (57 kDa) and desmin (53 kDa). Myometrial lysate was immunoprecipitated with sc-538, and immunoblotting of the immunoprecipitate with antibodies to alpha-actinin, desmin, and vimentin confirmed the presence of these proteins. The sc-538 nPR antibody therefore cross-reacts with cytoskeletal proteins that could be misinterpreted as nPR isoforms. Such misinterpretation has confused the progesterone response literature.

Expression of Nuclear Receptors and Cofacotrs in Human Endometrium and Myometrium

OBJECTIVE

To study the expression of nuclear receptors and cofactors in human endometrium and myometrium in proliferative and secretory phases of the menstrual cycle.

METHODS

Multiprobe ribonuclease protection assay and real-time reverse transcriptase polymerase chain reaction were used to quantitate mRNA levels of steroid receptors, vitamin D receptor (VDR), retinoic acid receptors (RAR), and cofactors AIB1 (amplified in breast cancer-1), CBP (cyclic adenosine monophosphate response element binding protein), pCAF (p300/CBP-associated factor), TIF2 (transcription intermediary factor-2), N-CoR (nuclear receptor corepressor), and SMRT (silencing mediator of repressed transcription). Cyclin A expression was analyzed to determine the proliferation status of the tissues.

RESULTS

The expression of androgen receptor, estrogen receptors alpha and beta, progesterone receptor, and RARalpha followed cyclin A expression. There was more abundant expression in the proliferative phase endometrium than in the secretory phase endometrium. Glucocorticoid receptor, VDR, RARbeta, and RARgamma were stably expressed during the menstrual cycle in both endometrium and myometrium. Cofactors N-CoR, SMRT, pCAF, CBP, TIF2, AIB1, and p300 mRNAs were expressed in all samples in both endometrium and myometrium. N-CoR, pCAF, AIB1, and p300 appeared not to be regulated when comparing proliferative and secretory phases of the cycle. Individual differences were found in the expression levels of both nuclear receptors and cofactors.

CONCLUSION

The menstrual cycle-dependent regulation of nuclear receptor expression was more apparent in the endometrium than in the myometrium, whereas cofactor expression was not cycle dependent. There were individual differences in the expression levels of different receptors and cofactors. In hormonal therapy these differences might result in different responses, depending on the patient as well as the ligand used.

The use of the Petri net method in the simulation modeling of mitochondrial swelling

Using photon correlation spectroscopy, which allows investigating changes in the hydrodynamic dia­meter of the particles in suspension, it was shown that ultrahigh concentrations of Ca2+ (over 10 mM) induce swelling of isolated mitochondria. An increase in hydrodynamic diameter was caused by an increase of non-specific mitochondrial membrane permeability to Ca ions, matrix Ca2+ overload, activation of ATP- and Ca2+-sensitive K+-channels, as well as activation of cyclosporin-sensitive permeability transition pore. To formalize the experimental data and to assess conformity of experimental results with theoretical predictions we developed a simulation model using the hybrid functional Petri net method.

PROTECTIVE EFFECTS OF POTASSIUM TRANSPORT IN MITOCHONDRIA FROM RAT MYOMETRIUM UNDER ACTIVATION OF MITOCHONDRIAL PERMEABILITY TRANSITION PORE

We demonstrated using PBFI K(+)-sensitive fluorescent probe an enhancement of both components of K(+)-cycle--the ATP-sensitive K(+)-uptake and quinine-sensitive K+/H(+)-exchange--under the Ca2+ induced opening of mitochondrial permeability transition pore (MPTP) in rat myometrium mitochondria. Addition of CaCl2 (100 μM to K(+)-free medium results in the enhancement of reactive oxygen species (ROS) production, which was eliminated by cyclosporine A. Addition of CaCl2 to K(+)-rich medium did not increase the rate of ROS production, but blocking of mitoK+(ATP)-channels with glybenclamide (10 mcM increased production of ROS. We conclude that K(+)-cycle exerts a protective influence in mitochondria from rat myometrium by regulation of matrix volume and rate of ROS production under the condition of Ca(2+)-induced MPTP.

[Protective effect of tiacalix[4]arene-tetrasulphonate on heavy metal inhibition of myometrium myosin subfragment-1 ATP-hydrolase activity]

Heavy metals have a negative effect on the contractility of uterine smooth muscles (myometrium), these effects can lead to various pathologies of a women reproductive system. To overcome these effects the methods for correcting the myometrium contractile activity are to be developed. Catalyzed by myosin ATPase ATP hydrolysis is the most important reaction in the molecular mechanism of myometrium contraction. We have found an inhibitory effect of 0.03-0.3 mM Ni2+, Pb2+ and Cd2+ on enzymatic hydrolysis of ATP by myosin subfragment-1 obtained from swine uterine smooth muscles. We have demonstrated that 100 μM thiacalix[4]arene-tetrasulphonate (C-798) recovered to the control level of ATPase activity of myosin subfragment-1 in the presence of heavy metal cations. One of the most probable mechanisms of C-798 corrective activity is based on its ability to chelate heavy metals, thus cations Pb, Cd and Ni can be removed from the incubation medium. Computer simulation has demonstrated that the protective effect of C-798 may also be the result of weakening the interaction of heavy metal ions with amino acid residues of the myosin molecule near the active site of ATP hydrolase. The obtained results can be used for further research aimed at assessing the prospects of thiacalix[4]arene-tetrasulfonate as pharmacological compounds.

Potential diagnostic biomarkers: differential expression of LMP2/β1i and cyclin B1 in human uterine leiomyosarcoma

AIMS AND BACKGROUND

Whilst most uterine smooth muscle neoplasms are benign, uterine leiomyosarcoma (Ut-LMS) is extremely malignant with a high incidence of metastasis and recurrence. Gynecological tumors are often associated with female hormone secretion, but no strong link has been detected between human Ut-LMS and the hormonal environment. In fact, the risk factors for Ut-LMS are poorly understood. In addition, no diagnostic biomarkers for differentiating between leiomyoma, a benign tumor, and malignant Ut-LMS have been found. Interestingly, mice that were homozygously deficient for LMP2/β1i were found to spontaneously develop Ut-LMS and exhibited a Ut-LMS prevalence of ~40% by 14 months of age. Thus, analyzing potential risk factors for Ut-LMS (such as LMP2/β1i) might aid the development of diagnostic biomarkers and clinical treatments for the condition.

METHODS AND STUDY DESIGN

Fifty-seven patients (age range: 32-83 years) who had been diagnosed with uterine mesenchymal tumors were chosen from a pathological archive. Tissue samples from these patients were fixed in 10% buffered formalin, incubated in 4% paraformaldehyde for 8 hours, and embedded in paraffin. Tissue sections were stained with hematoxylin and eosin for standard histological examination or were subjected to further processing for immunohistochemical (IHC) examination. Serial Ut-LMS, bizarre leiomyoma, leiomyoma, and myometrium sections were subjected to IHC staining of β-smooth muscle actin, estrogen receptor, cyclin B1, LMP2/β1i, calponin h1, ki-67, tumor protein p53, and progesterone receptor.

RESULTS

The Ut-LMS samples were positive for cyclin B1 and negative for LMP2/β1i, while the opposite result was obtained for bizarre leiomyoma, leiomyoma, and myometrium samples.

CONCLUSIONS

The expression pattern of LMP2/β1i and cyclin B1 might be a diagnostic biomarker for human Ut-LMS. Studies of the biological roles of LMP2/β1i and/or cyclin B1 could lead to the elucidation of new targets for therapies against Ut-LMS.

Calcium concentration response to uterine ischemia: a comparison of uterine fibroid cells and adjacent normal myometrial cells

OBJECTIVE

Uterine artery occlusion by laparoscopy (UAOL) has been used for the treatment of uterine fibroids and beneficial effects to patients have been shown in clinical studies since 2000. Fibroid cells are more susceptible to apoptosis than myometrial cells under hypoxic conditions, but the molecular mechanisms underlying this effect remain unclear. The aim of this study was to investigate the role of intracellular calcium (Ca(2+)) release mediated by Ca(2+) channel inositol 1,4,5 trisphosphate receptor1 (IP3R1)/ryanodine receptor1 (RYR1) in the apoptosis of uterine fibroid cells under hypoxia.

STUDY DESIGN

We compared the expressions of IP3R1 and RYR1 in fibroid and surrounding myometrial tissue from 20 patients before UAOL. After 6h treatment under hypoxia (1% O2) with or without Ca(2+) channel blockers (heparin or/and ruthenium red), the intracellular Ca(2+) concentration, cytochrome c (Cytc) protein and cell apoptosis were determined.

RESULTS

IP3R1 and RYR1 mRNA and protein levels were significantly higher in fibroid than in myometrial tissues. Under hypoxic conditions, Ca(2+) concentration in fibroid cells was significantly higher than in myometrial cells (Ca(2+): 82.69±16.92nmol/L vs 46.14±9.11nmol/L, P<0.05), and Cytc increased similarly in fibroid cells. These increases in Ca(2+) concentration, Cytc and cell apoptosis were significantly reversed by calcium blocker in fibroid cells.

CONCLUSION

This study demonstrated that intracellular calcium release mediated by IP3R1/RYR1 could induce apoptosis in uterine fibroid cells under hypoxic conditions, and was responsible for the susceptibility to apoptosis of fibroid cells under UAOL.

C-Met expression pattern in uterine leiomyoma

AIM

Growth factors take place in the formation and growth of uterine leiomyomas (LMs). Transforming growth factor beta (TGF-beta), epidermal growth factor (EGF), platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), fibroblast growth factor-2 (FGF-2), and insulin-like growth factor (IGF) contribute to the pathophysiology of LMs when they bind with a specific membrane receptor and transmit a signal into the cell. Little is known about hepatocyte growth factor (HGF) and its receptor system c-Met in formation and growth of uterine LMs. The aim of this study was to evaluate the c-Met receptor expression on human myometrium and uterine LMs.

MATERIALS AND METHODS

The study was performed on human myometrium and uterine LMs. Expression of c-Met receptor was evaluated by immunohistochemical analysis.

RESULTS

Overexpression of c-Met was found in all LM cases and in none of normal myometrium samples c-Met overexpression was seen.

CONCLUSION

HGF and c-Met receptor complex seem to have role in development of uterine LMs.

[Ca2+ accumulation study in isolated smooth muscle mitochondria using fluo-4 AM]

The opportunity of Ca2+-sensitive fluorescent dye Fluo-4 AM and spectrofluorimetry method application for the study of energy-dependent Ca2+ accumulation in mitochondria from uterus smooth muscle is proved. It has been found that the presence of mitochondrial preparation increases time-dependent fluorescent response considerably and this effect depends on Ca2+ concentration in the medium. Thus, in these conditions, deesterification active probe is formed which is sensitive to Ca2+. It is shown that the accumulation of calcium ions in mitochondria in the presence of Mg-ATP and succinate depends on exogenous Ca2+ concentration and is characterized by substrate saturating. The apparent activation constant of Ca2+ accumulation is 53.9 +/- 6.9 mM, which corresponds to the physiological concentration of the cation in the cell next to mitochondria. Transit addition of Ca2+-ionophore A23187 to the incubation me- dium caused a rapid release of ionized cation from mitochondria. When proton gradient on the inner mitochondrial membrane is dissipated by protonophore CCCP, in the case of suppressing the generation of the gradient by oligomycin and in the presence of ruthenium red that inhibits Ca2+ mitochondrial accumulation systems, Ca2+ entry is significantly reduced. The results indicate the prospects of using Fluo-4 AM to study the properties of the Ca2+ accumulation system in isolated mitochondria of the myometrium.

[Calix[4]arenes C-136 and C-137 hyperpolarize myometrium mitochondria membranes]

Calixarenes--supramolecular compounds interacting with bioactive molecules and ions that causes the changes in biochemical and biophysical processes. The aim of this work was to study the effects of calix[4]arenes C-136, C-137 and C-138 on the level of polarization of rat myometrium mitochondria membrane. Structure of synthesized calix[4]arene molecules was confirmed by the methods of 1H NMR and infra-red spectroscopy. Calix[4]arenes C-136 and C-137 possess two chalcone amide moieties at the lower rim, while the calix[4]arene C-138--only one. In case of calix[4]arenes C-136 and C-137 take place, accordingly, absence or presence of phenolic hydroxyl groups at the lower rim on the calix[4]arene skeleton. It was shown that calix[4]arenes C-136, C-137 and C-138 form micelles in a water medium and in the dimethylformamide (DMF). The irradiation of micelles with argon laser on flow cytometer results in appearance of autofluorescence. In the water medium calix[4]arene micelles interact with positively charged potential-sensitive fluorescent probe TMRM, that can testify to the presence of negative charge in these structures. However calix[4]arene micelles in DMF solution do not interact with TMRM. Mitochondrial membrane potential was measured using fluorescent dyes MTG and TMRM with confocal microscopy and fluorescent dye TMRM with flow cytometry. Experiments were conducted on myometrium cells in culture and on suspension of digitonin-permeabilized uterus myocytes. It was shown that a fluorescent signal was stable during time of experiment. Calix[4]arenes C-136 and C-137 (10 μM) hyperpolarize mitochondria membranes. A maximal effect was 173%. At the same time calix[4]arene C-138 did not influence on mitochondria membrane potential. Connection comes into question between structural organization of investigated calix[4]arene molecules and their influence on polarization of mitochondria membrane.

Characterization of the myometrial transcriptome in women with an arrest of dilatation during labor

OBJECTIVE

The molecular basis of failure to progress in labor is poorly understood. This study was undertaken to characterize the myometrial transcriptome of patients with an arrest of dilatation (AODIL).

STUDY DESIGN

Human myometrium was prospectively collected from women in the following groups: (1) spontaneous term labor (TL; n=29) and (2) arrest of dilatation (AODIL; n=14). Gene expression was characterized using Illumina® HumanHT-12 microarrays. A moderated Student's t-test and false discovery rate adjustment were used for analysis. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) of selected genes was performed in an independent sample set. Pathway analysis was performed on the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway database using Pathway Analysis with Down-weighting of Overlapping Genes (PADOG). The MetaCore knowledge base was also searched for pathway analysis.

RESULTS

(1) Forty-two differentially expressed genes were identified in women with an AODIL; (2) gene ontology analysis indicated enrichment of biological processes, which included regulation of angiogenesis, response to hypoxia, inflammatory response, and chemokine-mediated signaling pathway. Enriched molecular functions included transcription repressor activity, heat shock protein (Hsp) 90 binding, and nitric oxide synthase (NOS) activity; (3) MetaCore analysis identified immune response chemokine (C-C motif) ligand 2 (CCL2) signaling, muscle contraction regulation of endothelial nitric oxide synthase (eNOS) activity in endothelial cells, and triiodothyronine and thyroxine signaling as significantly overrepresented (false discovery rate <0.05); (4) qRT-PCR confirmed the overexpression of Nitric oxide synthase 3 (NOS3); hypoxic ischemic factor 1A (HIF1A); Chemokine (C-C motif) ligand 2 (CCL2); angiopoietin-like 4 (ANGPTL4); ADAM metallopeptidase with thrombospondin type 1, motif 9 (ADAMTS9); G protein-coupled receptor 4 (GPR4); metallothionein 1A (MT1A); MT2A; and selectin E (SELE) in an AODIL.

CONCLUSION

The myometrium of women with AODIL has a stereotypic transcriptome profile. This disorder has been associated with a pattern of gene expression involved in muscle contraction, an inflammatory response, and hypoxia. This is the first comprehensive and unbiased examination of the molecular basis of an AODIL.

Characterization of uterine leiomyomas by whole-genome sequencing

BACKGROUND

Uterine leiomyomas are benign but affect the health of millions of women. A better understanding of the molecular mechanisms involved may provide clues to the prevention and treatment of these lesions.

METHODS

We performed whole-genome sequencing and gene-expression profiling of 38 uterine leiomyomas and the corresponding myometrium from 30 women.

RESULTS

Identical variants observed in some separate tumor nodules suggested that these nodules have a common origin. Complex chromosomal rearrangements resembling chromothripsis were a common feature of leiomyomas. These rearrangements are best explained by a single event of multiple chromosomal breaks and random reassembly. The rearrangements created tissue-specific changes consistent with a role in the initiation of leiomyoma, such as translocations of the HMGA2 and RAD51B loci and aberrations at the COL4A5-COL4A6 locus, and occurred in the presence of normal TP53 alleles. In some cases, separate events had occurred more than once in single tumor-cell lineages.

CONCLUSIONS

Chromosome shattering and reassembly resembling chromothripsis (a single genomic event that results in focal losses and rearrangements in multiple genomic regions) is a major cause of chromosomal abnormalities in uterine leiomyomas; we propose that tumorigenesis occurs when tissue-specific tumor-promoting changes are formed through these events. Chromothripsis has previously been associated with aggressive cancer; its common occurrence in leiomyomas suggests that it also has a role in the genesis and progression of benign tumors. We observed that multiple separate tumors could be seeded from a single lineage of uterine leiomyoma cells. (Funded by the Academy of Finland Center of Excellence program and others.).

[Kinetic properties of calixarene C-90 action on the myometrial plasma membrane Ca2+,Mg2+-Atpase activity and on the Ca2+ concentration in unexcited cells of the myometrium]

Plasma membrane Ca2+,Mg2+-ATPase is an important element of general myometrium tonus control mechanism, which also makes a contribution to muscle tension relaxation after its contraction. Expiriments were done on the myometrial cell plasma membrane suspension, which was treated with 0.1% digitonin solution. The authors have investigated the inhibitory action of calix[4]arene C-90 (5,11,17,23-tetra(trifluor) methyl(phenylsulphonylimino)-methylamino-25,26,27,28-tetra propoxi-calix[4]arene) on the Ca2+,Mg2+-ATPase activity (the magnitude of 10.5 was 20.2 +/- 0.5 mkM). The inhibitory action of calix[4]arene C-90 on the activity of Ca2+, Mg2+-ATPase is explained as cooperative action of four trifluormethyl(phenylsulfonylimino)methylamino groups that are spatially oriented on the calix[4]-arene base rather than with the action of tetra-phenol macrocycle or separate pharmacophore sulphonilamidin groups. Considering established kinetic pattern of calix[4]arene C-90 inhibitory action on the plasma membrane Ca2+,Mg2+-ATPase activity, stationary kinetical model of basal calcium concentration control in unexcited uterus myocytes was developed. It is assumed that obtained results may be promising for creation of new generation ("supramolecular") pharmacological agent - uterus basal tonus stimulator - on the base of calix[4] arene C-90.

Assessment of myometrial concentrations of oestrogen and progesterone receptors in the lower uterine segment of full-term pregnancies in presence or absence of labour

OBJECTIVE

To assess the concentration of progesterone (PRs) and oestrogen (ORs) receptors of myometrium of full-term pregnant women in the myometrium of lower segment of the uterus in relationship with presence or absence of labour.

METHODS

This was a cross-sectional prospective study with 21 pregnant women, being 6 in labour (Group I) and 15 without labour (Group II). The biopsy of myometrium was realized during caesarian section, and the excised tissue was stained using immunohistochemical techniques for the quantification of the receptors, and with the aid of image-analysis software, the numbers of receptors for each hormone were determined spectrophotometrically. The Mann-Whitney test was used to compare the pregnant women in each study group with respect to the numbers of ORs and PRs. The Wilcoxon test was used to compare the concentration of ORs and PRs in each group separately.

RESULTS

The mean of gestational age was 39 weeks, (range, 37 to 41 weeks). The medians of PRs and ORs in pregnant women in labour (Group I) were 29.3 (range, 24.6-30.2) and 32.3 (range, 22.9-49.0), respectively. The medians of PRs and ORs in pregnant women without labour (Group II) were 43.6 (range, 23.6-70) and 43.9 (range, 18.3-62.6), respectively. We did not observe significant differences of the number of ORs and PRs in both groups (P = 0.13 and 0.37, resp.). The number of ORs was statistically more than that of PRs in Group II (Z calculated = 16.00).

CONCLUSION

The concentrations of PRs and ORs were similar in the myometrium of the lower uterine segment of pregnant women during and without labour, but the concentration of ORs was more than that of PRs in the myometrium of the lower uterine segment of pregnant women without labour.

[Structural and functional bases of the intermolecular interaction of calix[4]arene C-97 with myosin subfragment-1 of myometrium]

Calix[4]arene C-97 (code is shown) is the macrocyclic compound which has lipophilic intramolecular higly-structured cavity formed by four aromatic cycles, one of which on the upper rim is modified by methylene bisphosphonic group. It was shown that calix[4]arene C-97 (100 microM) efficiently inhibits ATPase activity of myosin subfragment-1 from pig myometrium, the inhibition coefficient I(0.5) being 83 +/- 7 microM. At the same time, this compound at 100 microM concentration significantly increases the effective hydrodynamic diameter of myosin subfragment-1, that may be indicative of intermolecular complexation between the calix[4]arene and myosin head. Computer simulation methods (docking, molecular dynamics, involving the Grid) have been used to clarify structural basis of the intermolecular interaction of calix[4]arene C-97 with myosin subfragment-1 of the myometrium; participation of hydrophobic, electrostatic and pi-pi (stacking) interactions between calix[4]arene C-97 and amino acid residues of myosin subfragment-1, some of them being located near the active site of the ATPase has been found out.

Immunohistochemical analysis of p16 expression in uterine smooth muscle tumors

The expression of p16 as a tumor suppressor protein was evaluated in a retrospective analysis of paraffin-embedded tissue specimens of leiomyosarcoma (LMS), leiomyoma (LM) and normal myometrium. In this study, we investigated by immunohistochemistry p16 expression in 15 LMSs, 15 LMs and ten normal myometrium. Strong expression of p16 was found in 12 of the 15 LMSs and in three cases weak expression; three LMs had focal and weak p16 staining but none of the normal myometrium. A statistically significant difference regarding the frequency of p16 protein expression was observed between LMS and LM (p: 0.0001). We concluded that the results of this study confirm the overexpression of p16 in LMS. Therefore, the present study suggests that p16 might be a useful immunohistochemical marker which could help in distinguishing uterine LMS from LM and its benign variants.

Identification of a novel corticotropin-releasing hormone type 1beta-like receptor variant lacking Exon 13 in human pregnant myometrium regulated by estradiol-17beta and progesterone

Two types of CRH receptors mediate the diverse biological functions of CRH and CRH-related peptides. The type 1 CRH-R (CRH-R1) is extensively targeted by pre-mRNA splicing mechanisms that give rise to multiple mRNA splice variants. RT-PCR amplification of CRH-R1 sequences from human myometrium yielded cDNAs that encode a novel CRH-R1 splice variant with structural characteristics identical with CRH-R1β except a 14-amino acid deletion in the seventh transmembrane domain characteristic of the CRH-R1d. Transient expression of the hybrid CRH-R1 variant (CRH-R1β/d) in human embryonic kidney 293 cells revealed primarily intracellular expression, although some plasma membrane protein expression was also detectable. CRH bound to CRH-R1β/d with affinity comparable with the CRH-R1β; however, it was unable to stimulate adenylyl cyclase or other second messengers. Using a semiquantitative RT-PCR assay, CRH-R1β/d mRNA transcript was detected in human pregnant, but not nonpregnant, myometrium as early as 31 wk of gestation. Furthermore, in human pregnant myometrial cells, the relative expression of CRH-R1β and CRH-R1β/d mRNA appeared to be regulated by steroids; CRH-R1β/d mRNA expression was increased by estradiol-17β, whereas CRH-R1β mRNA levels were increased by progesterone. Progesterone also substantially increased CRH-R1α mRNA levels and cellular responsiveness to CRH as determined by increased agonist binding and cAMP production as well as resistance to CRH-R heterologous desensitization by phorbol esters. These results provide novel evidence for distinct patterns of CRH-R1 splicing and identify specific steroid-mediated regulation of CRH-R1 variant expression, which might be important for modulating CRH actions during human pregnancy and labour.

Lipidomic analysis reveals prostanoid profiles in human term pregnant myometrium

Prostanoids modulate the activity of human pregnant myometrium and their functional role can be appreciated through characterisation of prostanoid receptors and tissue concentration of prostanoids. We have applied a lipidomic approach to elucidate the profile of prostanoids in human non-labouring and labouring myometrium. We have identified a total of nineteen prostanoids including prostacyclin, thromboxanes, prostaglandins and dihydro-prostaglandins. Prostacyclin was the predominant prostanoid in both non-labouring and labouring myometria, with PGD(2) and PGF(2alpha) being the second most abundant. Although the total amount of prostanoids was increased in the labouring tissue, PGE(2) and 13,14-dihydro-15-keto-PGE(2) were the only prostanoids to increase significantly at early and late labour (p< or =0.001). Our data suggest that PGF(2alpha) plays an important role in parturition, whilst the increase in PGE(2) could occur to facilitate cervical dilation and relaxation of the lower myometrium during labour. Although the elevation in TXA(2) was less marked than expected, in terms of translation to function even a relatively small increase in the level of this potent spasmogen may have significant effects.

Nitric oxide detection by DAF (diaminofluorescein) fluorescence in human myometrial tissue

Nitric oxide (NO) is considered to be involved in the modulation of uterine contractility. In the present pilot study, the direct detection of intracellular NO in pregnant human myometrial tissues has been investigated by using the fluorescent indicator 4,5-diaminofluorescein-2 diacetate (DAF-2DA). Pregnant myometrial tissue samples were obtained during Cesarean sections between week 34 and 40 of gestation before the onset of labor. Living explants were loaded with 10 microM DAF-2DA, stimulated with 1 mM arginine, subsequently fixed with glutaraldehyde and examined by fluorescence microscopy. The presence of NO synthases (NOS) was studied by immunohistochemistry. After application of DAF-2DA, DAF fluorescence was located primarily in blood vessels and to a minor extent in myometrial cells. By immunohistochemistry, strong endothelial NOS (eNOS) staining was found in vessel walls. In myometrial cells weak staining of eNOS and inducible NOS was observed. We conclude that the direct NO detection by DAF-2DA provides a new and independent method to identify sites of NO production in myometrium and other heterogeneous tissues.

The expression of transforming growth factor beta in pregnant rat myometrium is hormone and stretch dependent

From a quiescent state in early pregnancy to a highly contractile state in labor, the myometrium displays tremendous growth and remodeling. We hypothesize that the transforming growth factor beta (TGFbeta) system is involved in the differentiation of pregnant myometrium throughout gestation and labor. Furthermore, we propose that during pregnancy the mechanical and hormonal stimuli play a role in regulating myometrial TGFbetas. The expression of TGFbeta1-3 mRNAs and proteins was examined by real-time PCR, Western immunoblot, and localized with immunohistochemistry in the rat uterus throughout pregnancy and labor. Tgfbeta1-3 genes were expressed differentially in pregnant myometrium. Tgfbeta2 gene was not affected by pregnancy, whereas the Tgfbeta1 gene showed a threefold increase during the second half of gestation. In contrast, we observed a dramatic bimodal change in Tgfbeta3 gene expression throughout pregnancy. Tgfbeta3 mRNA levels first transiently increased at mid-gestation (11-fold on day 14) and later at term (45-fold at labor, day 23). Protein expression levels paralleled the changes in mRNA. Treatment of pregnant rats with the progesterone (P4) receptor antagonist RU486 induced premature labor on day 19 and increased Tgfbeta3 mRNA, whereas artificial maintenance of elevated P4 levels at late gestation (days 20-23) caused a significant decrease in the expression of Tgfbeta3 gene. In addition, Tgfbeta3 was up-regulated specifically in the gravid horn of unilaterally pregnant rats subjected to a passive biological stretch imposed by the growing fetuses, but not in the empty horn. Collectively, these data indicate that the TGFbeta family contributes in the regulation of myometrial activation at term integrating mechanical and endocrine signals for successful labor contraction.

Selective angiotensin II AT2 receptor agonists devoid of the imidazole ring system

A versatile parallel synthetic method to obtain three series of non-cyclic analogues of the first drug-like selective angiotensin II AT(2) receptor agonist (1) has been developed. In analogy with the transformation of losartan to valsartan it was demonstrated that a non-cyclic moiety could be employed as an imidazole replacement to obtain AT(2) selective compounds. In all the three series, AT(2) receptor ligands with affinities in the lower nanomolar range were found. None of the analogues exhibited any affinity for the AT(1) receptor. Four compounds, 17, 22, 39 and 51, were examined in a neurite outgrowth cell assay. All four compounds were found to exert a high agonistic effect as deduced from their capacity to induce neurite elongation in neuronal cells, as does angiotensin II.

Expression of small heat shock-related protein 20 (HSP20) in rat myometrium is markedly decreased during late pregnancy and labour

The underlying mechanisms regulating uterine contractions during labour are still poorly understood. Heat shock protein 20 (HSP20) is known to be present at high levels in smooth muscle and implicated in muscle relaxation, but HSP20 expression in the myometrium is completely undetermined. Since HSP20 has been implicated in smooth muscle relaxation, we hypothesized that HSP20 would be highly expressed in the rat myometrium during early and mid-pregnancy when the myometrium is relatively quiescent. Northern blot analysis particularly demonstrated that HSP20 mRNA detection was significantly decreased from day (d) 22 of pregnancy to 1-day post-partum (PP) compared with d6 (P < 0.05). HSP20 mRNA detection was also significantly decreased from d22 to d23 of gestation compared with non-pregnant (NP) samples. Immunoblot analysis showed that detection of HSP20 was significantly decreased at d23 compared with d12 and d15 (P < 0.05). HSP20 detection also significantly decreased at PP compared with d15 (P < 0.05). Immunofluorescence analysis demonstrated that after d15, plasma membrane-associated localization of HSP20 decreased markedly in both circular and longitudinal muscle layers. In addition, HSP20 was detectable near cell membranes at much higher levels in the longitudinal muscle layer of progesterone-treated pregnant rats (delayed labour) at all gestational time points examined, compared with controls. Our results demonstrate that HSP20 mRNA and protein are highly expressed during early and mid-pregnancy and then the expression markedly decreases during late pregnancy and labour. The observed patterns of HSP20 expression are consistent with a potential role for HSP20 in facilitating myometrium quiescence during early and mid-pregnancy.

Retinoic acid pathway genes show significantly altered expression in uterine fibroids when compared with normal myometrium

Fibroids are benign neoplasms of myometrial smooth muscle cells (SMC). Despite being the most common tumor in humans, their etiology is poorly understood. Recent microarray studies have demonstrated that multiple members of the retinoid pathway are differentially expressed between myometrium and fibroids. The aim of this present study was to investigate gene expression of members of the retinoid pathway in matched myometrium and fibroids. We have demonstrated differential gene expression of two binding proteins [cellular retinol-binding proteins (CRBP) 1 and 2], three enzymes [alcohol dehydrogenase 1 (ADH1), aldehyde dehydrogenase (ALDH1) and retinol dehydrogenase (RODH)] and two receptors [retinoid X receptors (RXR) alpha and gamma] involved in the retinoid pathway by real-time PCR. There were no differences in gene expression for retinoid receptors RARalpha, beta, gamma and RXRbeta, and for the metabolizing enzyme cytochrome P450, family 26 subfamily A. We confirmed results for ADH1, ALDH1, CRBP1 and CRABP2 at the protein level by western blot. Using immunohistochemistry these proteins were mostly localized to myometrial and fibroid SMC. An exception to this was ALDH1 protein, which displayed strong staining localized to cells of the connective tissue, presumably fibroblasts, with a striking differential expression pattern between myometrium and fibroids. These results demonstrate that the retinoid pathway is altered in fibroids when compared with normal myometrium and specifically identify ALDH1 in fibroid fibroblasts. These alterations can lead to aberrant retinoic acid (RA) production and signaling, and alter the expression of RA target genes, which may be an important step in fibroid development.

Quantitative profiling of epoxyeicosatrienoic, hydroxyeicosatetraenoic, and dihydroxyeicosatetraenoic acids in human intrauterine tissues using liquid chromatography/electrospray ionization tandem mass spectrometry

A reversed-phase liquid chromatography negative ion electrospray tandem mass spectrometry (LC/ESI-MS/MS) method was developed and validated to quantify a range of physiologically relevant eicosanoids, including 5,6-, 8,9-, 11,12-, and 14,15-epoxyeicosatrienoic acids (EETs); 5-, 8-, 9-, 12-, and 15-hydroxyeicosatetraenoic acids (HETEs), and 5,6-, 8,15-, and 12,20-dihydroxyeicosatetraenoic acids (DiHETEs) in human intrauterine tissues. A solid-phase extraction method was employed to extract the eicosanoids, and gradient LC separation was performed on a Kromasil C(18) column. Mass spectrometric detection was performed by multiple reaction monitoring over a 31-min run time. The calibration curves were linear over the range of 4-400pmol/g tissue, and the intra- and interday precision and accuracy were within a coefficient of variation of 2.0 to 27.4% and 4.6 to 17.9%, respectively. The lower limit of quantitation was 1.0pmol/g tissue. The method was applied successfully to the characterization and quantitation of eicosanoids in the different compartments of human intrauterine tissues. Our results demonstrate significantly greater amounts of HETEs than of either the EETs or DiHETEs (P<0.001), irrespective of tissue type. Specifically, the metabolite 12-HETE was significantly more abundant (P<0.001) than all other HETEs. Of the EET metabolites, 5,6-EET predominated (P<0.001). A significant negative correlation between EETs and HETEs for all tissues (rho=-0.390, P<0.001) was identified, implying a biological feedback mechanism between these two arachidonate metabolite classes.

In Situ Calcium Signaling: No Calcium Sparks Detected in Rat Myometrium

Controlled uterine smooth muscle activity is essential for our reproductive health. While we understand reasonably well the steps that produce contraction following a rise in intracellular [Ca], the mechanism controlling excitability and thus the rise of Ca, is less well understood. Here we examine the role of the internal Ca sore, the sarcoplasmic reticulum (SR), and its relation to surface membrane ion channels. We show that despite having a well-developed SR, the rat uterus does not produce the elemental and local Ca signals, known as Ca sparks. This in turn has consequences for excitability, as the negative feedback loop between these Ca signals and Ca-activated K (BK) channels on the surface membrane is lost. This may be important for producing the powerful long-lasting contractions of the uterus required during labor.

Human myometrium and leiomyomas express gonadotropin-releasing hormone 2 and gonadotropin-releasing hormone 2 receptor

OBJECTIVE

To determine the presence or absence of a second form of GnRH (GnRH2) and corresponding receptor (GnRHR2) in human uterine myometrium and leiomyomata.

DESIGN

Evaluation of human leiomyoma and patient-matched myometrium of differential mRNA and protein expression of GnRH2 and GnRHR2.

SETTING

University hospital.

PATIENT(S)

Eight women undergoing medically indicated hysterectomy for symptomatic fibroids.

INTERVENTION(S)

Microarray analysis, reverse-transcriptase polymerase chain reaction (RT-PCR), real-time RT-PCR, and immunohistochemistry.

MAIN OUTCOME MEASURE(S)

Expression of mRNA and protein in leiomyoma and patient-matched myometrium.

RESULT(S)

Microarray analysis demonstrated expression, and we confirmed the findings by RT-PCR. Real-time RT-PCR demonstrated equivalent expression of the genes in leiomyoma compared with patient-matched myometrium (0.99-fold for GnRH2 and 1.28-fold for GnRHR2). Immunohistochemistry confirmed the expression of GnRH2 protein in both leiomyoma and myometrium.

CONCLUSION(S)

A second form of GnRH and corresponding receptor exists in the fibroid and myometrium. We speculate that an autocrine loop exists. Our findings provide further evidence that GnRH agonists may interact directly with GnRH receptors present in uterine fibroids.

Cigarette smoke extract enhances oxytocin-induced rhythmic contractions of rat and human preterm myometrium

Although smoking during pregnancy is a major risk factor for preterm delivery, the underlying mechanism by which smoking stimulates uterine contractions is still poorly understood. In the present study, we tried to clarify the effects of smoking on myometrial contractility induced by oxytocin (OT) using cigarette smoke extract (CSE). Myometrial strips, which were taken from the rat on day 16 of pregnancy, and from human preterm and term delivery groups, were incubated overnight with several doses of CSE at 37 degrees C under non-hormonal conditions. The uterine contractile sensitivity and activity (force and frequency) upon exposure to OT were investigated. Furthermore, the expression levels of oxytocin receptor (OTR) mRNA in the myometrial strips were investigated by real-time PCR. Contractile sensitivity to OT in the rat CSE (10(-7) pieces/ml) group was found to be significantly higher than in the control group (P < 0.05). Contractile activity did not differ between the CSE and control groups. The expression levels of rat OTR mRNA in the CSE (10(-7) pieces/ml) group were significantly higher than in the control group (P < 0.01). Similarly, in preterm myometrial strips, the expression levels of human OTR mRNA in the CSE (10(-7) pieces/ml) group were significantly higher than in the control group (P < 0.05). These findings suggest that CSE directly increases the contractile sensitivity of preterm myometrium in response to OT by upregulating the expression of OTR mRNA and thereby increases the risk of preterm delivery in women, who smoke during pregnancy.

Characterization of cellular retinoid-binding proteins in human myometrium during pregnancy

Many complementary or competing signalling pathways bear an influence on the myometrium at any one time, and because the retinoic acid signalling pathway influences differentiation of a wide array of human tissues, this may be one of the determinants of myometrial differentiation during pregnancy. We have explored the novel hypothesis that the retinoids may act as important regulators in controlling the differentiated state of the human myometrium during pregnancy by characterizing the expression profiles for cellular retinoid-binding proteins CRBPI, CRABPI and CRABPII in non-pregnant, pregnant (non-labouring) and labouring human myometrium taken from the functionally distinct upper and lower uterine segments. In addition, we have investigated the effect of all-trans retinoic acid (ATRA) on the expression of several retinoic acid response genes including cyclooxygenase-2 (COX-2) and connexin-43 (Cx-43). Different spatial and temporal patterns of expression were observed for CRBPI, CRABPI and CRABPII within the upper and lower uterine segments through the three trimesters of pregnancy and in labour. Furthermore, the expression of COX-2, Cx-43, CRABPI, the transcription factor c-Jun and the retinoic acid receptor RARbeta altered in response to different concentrations of ATRA, suggesting that the differential expression of cellular retinoid-binding proteins may lead to different levels of retinoic acid being delivered to its nuclear targets, leading to the differential expression of specific target genes within the myometrium during pregnancy.

Redistribution of aquaporins 1 and 5 in the rat uterus is dependent on progesterone: a study with light and electron microscopy

During early pregnancy in the rat there is a dramatic reduction in luminal fluid which is associated with uterine receptivity for blastocyst implantation. This study investigates the presence and distributional changes of several members of the aquaporin (AQP) family in the rat uterus in response to hormonal regime. An increase in apical AQP5 protein expression was found in response to progesterone alone or in combination with oestrogen, which is similar to that seen at the time of implantation. AQP1 was found in endothelial cells of the endometrium and in the inner circular layer of smooth muscle, with maximal protein expression seen after three doses of progesterone plus 8 hr of oestrogen treatment. These results, for the first time, show that the up-regulation of AQP5 in the apical plasma membrane of uterine epithelial cells and AQP1 in the inner circular layer of myometrium, is dependent on progesterone. Furthermore, unlike during normal pregnancy, there is no differential gradient of AQP5 expression between mesometrial and antimesometrial poles of the progesterone treated uterus. Hence it is suggested that the differential gradient of AQP5 is dependent on the presence of a blastocyst, in addition to the appropriate hormonal environment.

[Concentration of annexin V in gestational tissues: placenta, fetal membranes, myometrium and amniotic fluid]

THE BACKGROUND: It is believed that annexin V, an anticoagulant protein abundant in trophoblast, prevents circulating blood in the intervillous space from hypercoagulability and fibrin deposition. Distribution and the role of annexin V localized in other gestational tissues like myometrium and fetal membranes, as well as in amniotic fluid is unknown. The aim of this study was to determine the concentration of annexin V in the tissues under consideration.

STUDY DESIGN

The study group consisted of 40 healthy women at the 1st stage of labour, 16 of whom delivered by cesarean section. The strips of myometrium, placenta and fetal membranes, as well as the samples of amniotic fluid and the venous blood, were collected during surgery. Homogenates were prepared from the tissues. Annexin V was measured by immunoenzymatic method (ELISA).

RESULTS

Concentration of annexin V in the placenta was 122.65 +/- 33,14 ng/mg protein, in fetal membranes 136.31 +/- 49.30 ng/mg protein and in myometrium 65.40 +/- 30.72 ng/mg protein. There was a statistical difference between the concentrations in placenta and fetal membranes vs. myometrium (p<0.05). In amniotic fluid annexin V was found to be in low concentration (4.46 +/- 2.59 ng/ml, i.e., 1.60 +/- 1.21 ng/mg protein) while in blood plasma it was extremely low, over 6000 times lower than in placenta.

CONCLUSION

Annexin V is present not only in placenta, but also in fetal membranes and myometrium. Its concentration in fetal membranes is similar to that in placenta, while in myometrium it is 50% lower. Annexin V found in newly discovered sites probably plays a similar role like placental annexin V.

[Involvement of adenylyn cyclase signaling mechanisms in relaxing effect of relaxin and insulin on the rat uterus, trachea and human myometrium]

Participation of adenylyl cyclase signaling mechanisms of relaxin and insulin action in their regulating influence on the process of relaxation of the rat uterine and tracheal smooth muscles and human myometrium was shown. The study was based on the discovery of novel adenylyl cyclase signaling mechanisms of relaxin and insulin action in the muscle of vertebrates which involve: receptor --> Gi protein (betagamma dimer) --> phosphatidylinositol-3-kinase --> protein kinase Csigma (zeta) --> Gs protein --> adenylyl cyclase --> cAMP. In the rat uterus, trachea and human myometrium, relaxin, insulin and isoproterenol induced relaxation of KCl-contraction. The order of efficiency of the agents based upon their ability to induce the inhibiting effect on the KCl-contraction was as follows: relaxin = insulin > isoproterenol. The hormones induce activating effect on adenylyl cyclase leading to production of cAMP in the rat uterine and tracheal smooth muscles and human myometrium. It is shown that cAMP reproduces relaxing effect of the hormones under study. Thus, the involvement of novel adenylyl cyclase signaling mechanisms of relaxin and insulin action in realization of their relaxation effect on rat uterus, trachea and human myometrium was revealed for the first time.

Leptin and leptin receptor expression in the myometrium and uterine myomas: Is leptin involved in tumor development?

Leptin, the product of the obesity (ob) gene, along with its receptors (Ob-Rs), is expressed in several tissues and organs. Evidence has been provided that leptin, in addition to being involved in obesity development, plays a role in the regulation of the female reproductive system, angiogenesis and tumor growth. Uterine myoma is a rather common disease that develops more frequently in obese than lean women, where plasma leptin concentrations are elevated. RT-PCR and Western blotting showed that leptin was expressed, as mRNA and protein, in several uterine myomas but not in normal myometrium, while leptin receptors were expressed in both tissues. Immunocytochemistry indicated that leptin-immunoreactivity was located in both myometrial cells and blood-vessel walls of uterine myomas. Leptin(22-56), at concentrations of 10(-7) and 10(-6) M, enhanced the proliferative activity of both the normal myometrium and myoma cells in primary culture. Taken together, our findings allow us to suggest that leptin, acting through autocrine-paracrine mechanism(s), may be involved in the development of uterine myomas.

Evaluation of nucleolar organizer region (NOR) parameters in the uterine leiomyoma

Nucleolar organizer regions (NORs) were assessed in 27 women affected by uterine leiomyoma. Tissue samples obtained during surgery were silver-stained according to the method of Ploton et al. The assessed parameters were as follows: the number of argyrophylic nucleolar organizer regions (AgNORs) per nucleus, single AgNOR area, AgNOR intranuclear distribution, and AgNOR coefficient. The parameters were assessed quantitatively. It was found that the AgNOR coefficient was higher in uterine leiomyoma compared to the normal smooth muscle cells. The development of leiomyoma is associated with a marked decrease in myocyte nucleolar area, which accounts for 30% of the nucleus in the normal myometrium. With the comparable AgNOR number in the single nucleus, there were no differences in the single AgNOR granule area (1.21 microm2 +/- 0.047 and 1.11 microm2 +/- 0.025 in normal myometrium and in leiomyoma, respectively). In the normal myometrium, there was a positive correlation between nuclear area and the single AgNOR granule area, as well as between the AgNOR coefficient and the single AgNOR granule area. There was also a negative correlation between the number of granules per nucleus and their central and peripheral intranuclear distribution. The development of leiomyoma was associated with loss of all correlations observed in the control group.

C-kit immunopositive interstitial cells (Cajal-type) in human myometrium

Previous reports describing Cajal-like interstitial cells in human uterus are contradictory in terms of c-kit immunoreactivity: either negative (but vimentin-positive) in pregnant myometrium, or positive, presumably in the endometrium. The aim of this study was to verify the existence of human myometrial Cajal-like interstitial cells (m-CLIC). Six different, complementary approaches were used: 1) methylene-blue supravital staining of tissue samples (cryosections), 2) methylene blue and Janus green B vital staining (m-CLIC and mitochondrial markers, respectively), and 3) extracellular single-unit electrophysiological recordings in cell cultures, 4) non-conventional light microscopy on glutaraldehyde/osmium fixed, Epon-embedded semi-thin sections (less than 1 microm) stained with toluidine blue (TSM), 5) transmission electron microscopy (TEM), and 6) immunofluorescence (IF). We found m-CLIC in myometrial cryosections and in cell cultures. In vitro, m-CLIC represented approximately 7% of the total cell number. m-CLIC had 2-3 characteristic processes which were very long (approximately 60 microm), very thin (< or =0.5 microm) and moniliform. The dilated portions of processes usually accommodated mitochondria. In vitro, m-CLIC exhibited spontaneous electrical activity (62.4+/-7.22 mV membrane potentials, short duration: 1.197+/-0.04 ms). Moreover, m-CLIC fulfilled the usual TEM criteria, the so-called 'gold' or 'platinum' standards (e.g. the presence of discontinuous basal lamina, caveolae, endoplasmic reticulum, and close contacts between each other, with myocytes, nerve fibers and/or capillaries etc.). IF showed that m-CLIC express CD117/c-kit, sometimes associated with CD34, with vimentin along their processes. In conclusion, we describe myometrial Cajal-like interstitial cells that have affinity for methylene blue and Janus green B vital dyes, fulfill (all) TEM criteria, express CD117/c-kit and have spontaneous electric activity.

Expression of TASK and TREK, two-pore domain K+ channels, in human myometrium

Two-pore domain K+ channels are an emerging family of K+ channels that may contribute to setting membrane potential in both electrically excitable and non-excitable cells and, as such, influence cellular function. The human uteroplacental unit contains both excitable (e.g. myometrial) and non-excitable cells, whose function depends upon the activity of K+ channels. We have therefore investigated the expression of two members of this family, TWIK (two-pore domain weak inward rectifying K+ channel)-related acid-sensitive K+ channel (TASK) and TWIK-related K+ channel (TREK) in human myometrium. Using RT-PCR the mRNA expression of TASK and TREK isoforms was examined in myometrial tissue from pregnant women. mRNAs encoding TASK1, 4 and 5 and TREK1 were detected whereas weak or no signals were observed for TASK2, TASK3 and TREK2. Western blotting for TASK1 gave two bands of approximately 44 and 65 kDa, whereas TREK1 gave bands of approximately 59 and 90 kDa in myometrium from pregnant women. TASK1 and TREK1 immunofluorescence was prominent in intracellular and plasmalemmal locations within myometrial cells. Therefore, we conclude that the human myometrium is a site of expression for the two-pore domain K+ channel proteins TASK1 and TREK1.

[Epidermal growth factor (EGF) in uterine leiomyoma during tumour growth]

OBJECTIVES

Extracellular matrix is a place where various growth factors are bound and immobilised. It is expected that leiomyoma-associated remodelling of extracellular matrix in the uterus may be evoked by changes in the content of some growth factors.

DESIGN

The amount and distribution of EGF in the normal myometrium and in the leiomyoma during various growth stages were investigated.

MATERIAL AND METHODS

The assay of EGF was carried out with the use of ELISA commercial kit. SDS/polyacrylamide gel electrophoresis of tissue extracts followed by Western immunoblot was performed.

RESULTS AND CONCLUSIONS

It was found that all investigated tissues contained endogenous EGE Extractability of EGF depended on type of extracting solvent. Only slight amount of EGF could be extracted by 1 M acetic acid. Much more EGF could be solubilized in 0.05M Tris/HCl, pH 7.6. Our results showed that EGF bound to the uterus (normal and leiomyoma) components of different molecular mass. It is of interest that some components of both, acidic and neutral extracts (myometrium and leiomyomas) were not able to bind exogenous 125I-labelled EGF.

Differential expression of mesotocin receptors in the uterus and ovary of the pregnant tammar wallaby

Mesotocin, an oxytocin-like peptide, is released in highest concentrations during parturition in macropodid marsupials. In late pregnant wallabies, uterine sensitivity to mesotocin increases markedly in the myometrium of the gravid uterus. This coincides with a significant increase in myometrial mesotocin receptor concentrations 3–4 days before term. To date, there is no information on mesotocin receptor gene expression in female wallaby reproductive tissues. This study aimed to examine mesotocin receptor gene expression in the uterus and ovaries of pregnant tammar wallabies, and to localise mesotocin receptors within the uterus. An RT-PCR strategy produced a consensus nucleotide sequence of 834 bp, which encoded 278 amino acids of transmembrane domains I to VI. This protein sequence has approximately 80% homology with the bovine and rat oxytocin receptor exon 2 region. Only one mesotocin receptor was detected in the tammar genome. The myometrium and mammary gland both expressed a 4.1 kb mesotocin receptor gene transcript. Myometrial mesotocin receptor gene expression increased on day 22 of the 26-day gestation and was significantly higher in the gravid than the non-gravid uterus in late pregnancy. This pattern of mesotocin receptor gene expression paralleled mesotocin receptor concentrations. Mesotocin binding sites were localised only to the myometrium, the highest densities being observed in the gravid uterus. Finally, this study showed high expression of mesotocin receptors in the corpus luteum. The pattern of luteal mesotocin receptor expression differed from the myometrium, with a decrease in mesotocin receptors occurring on the day of expected births.

Small heat shock protein 27 (Hsp27) expression is highly induced in rat myometrium during late pregnancy and labour

The underlying mechanisms that regulate uterine contractions during labour are still poorly understood. A candidate regulatory protein is heat shock protein 27 (Hsp27). It belongs to the small heat shock protein family and can regulate actin cytoskeleton dynamics, act as a chaperone, and may regulate contractile protein activation. As a result, we hypothesized that Hsp27 expression would be highly induced during late pregnancy and labour. Hsp27 mRNA expression was significantly elevated (P <0.05) on days 17 to 22 of gestation. In addition, immunoblot analysis demonstrated that detection of total Hsp27 increased (P <0.05) between day 21 and 1 day post-partum (PP) inclusive. Since phosphorylation of Hsp27 has been reported to be a prerequisite for smooth muscle contraction, we examined the temporal and spatial expression of Ser-15 phosphorylated Hsp27. Immunoblot analysis showed that the detection of Ser-15 phosphorylated Hsp27 significantly increased (P <0.05) between days 19 and 23 (active labour) inclusive, in parallel with detection of total Hsp27. Immunocytochemical analysis of Ser-15 phosphorylated Hsp27 expression in situ demonstrated that phosphorylated Hsp27 in circular muscle became detectable in peri-nuclear and membrane regions on days 19 to 22, but was primarily restricted to the cytoplasm on days 23 to PP. In contrast, phosphorylated Hsp27 in longitudinal muscle was primarily detected in myocyte membranes on days 15 to 22, and then also became detectable in the cytoplasm of myocytes on days 23 and PP. Our results demonstrate that Hsp27 expression is highly upregulated during late pregnancy and labour and suggest that Hsp27 is a potential candidate contraction-associated protein.

Immunohistochemical studies on the progesterone receptor (PR) in the sow uterus during the oestrous cycle and in inseminated sows at oestrus and early pregnancy

Physiological changes in the sow uterus involve the regulation by progesterone and its receptor proteins (PR). Therefore, the aim of the present study was to investigate the localization of PR during different stages of the oestrous cycle and in inseminated sows during early pregnancy by use of immunohistochemistry. Uterine samples were collected from cyclic and inseminated sows at different stages of the oestrous cycle and early pregnancy. The samples were fixed in 10% formaldehyde and embedded in paraffin. Immunohistochemistry was done by use of a mouse monoclonal antibody to PR. The highest PR immunostaining in the surface epithelium was observed at oestrus/5–6 h after artificial insemination (AI) and early dioestrus/70 h after AI. In the glandular epithelium, the highest level of PR was found at oestrus with the lowest at late dioestrus/d 19. Higher levels of PR were observed in inseminated groups compared with cyclic sows. In the myometrium, a high level of PR was found at oestrus, while stromal PR cells were constantly present throughout the oestrous cycle and at different stages of early pregnancy. In conclusion, this study shows that the immunopresence of PR in the sow uterus differed between uterine compartments at the same reproductive stage. Differences were also found for some uterine compartments between cyclic and inseminated/early pregnant sows. The relatively consistent immunostaining of PR in the stroma strengthens a stromal role in the regulation of physiological activities in the sow uterus during the oestrous cycle as well as early pregnancy.

Identification and localization of prostaglandin E2 receptors in upper and lower segment human myometrium during pregnancy

Prostaglandin E2 (PGE2) plays a key role in the maintenance of human pregnancy and labour onset. PGE2 can elicit diverse actions within the uterus depending on the PGE2 receptors (EP1, EP2, EP3 and EP4) expressed. By signalling through different intracellular pathways the EP receptors may inhibit or promote smooth muscle contractility. Nine different EP3 receptor splice variants have been identified with divergent signalling pathways. RT-PCR and immunohistochemistry were utilized to identify and localize EP receptor isoforms within the upper segment (US) and lower segment (LS) myometrium. EP1 was significantly increased in the LS myometrium with term labour. EP3 (and EP3 splice variants EP3I(1b), EP3II, EP3III and EP3IV) was down-regulated in pregnancy (US and/or LS) with a further decrease at term labour in the LS. Overall, expression of EP2 was significantly higher in the LS while EP3 was significantly higher in the US. No significant EP4 changes were observed. Consistent with the RT-PCR results, immunohistochemistry confirmed the presence and, interestingly, showed nuclear localization of EP receptors in the myometrium with higher EP1 expression and lower expression of EP3. The differential regulation of EP receptors within the myometrium indicates that they may play a role in controlling the onset and maintenance of human labour.

Expression of scaffolding, signalling and contractile-filament proteins in human myometria: effects of pregnancy and labour

Successful parturition requires the co-ordination of numerous myometrial signalling events to allow for timely and efficient uterine contractions. Late pregnancy and labour onset in humans may be associated with changes in the expression of myometrial proteins implicated in such uterine contractile signal integration. Accordingly, in myometria from non-pregnant women and pregnant women, not in labour or in labour, we examined the content of putative plasmalemmal scaffolding proteins (caveolin-1 and -2) and compared these to the proportions of signal transducing rho-associated kinases (ROKalpha and beta) and contractile filament-associated proteins alpha-actin, myosin regulatory light chain (MLC(20)) and h-caldesmon. There was no effect of pregnancy or labour on the proportion of caveolin, ROK betaor alpha-actin. However, pregnancy was associated with a decrease in ROKalpha and MLC(20) such that ROK alpha: alpha-actin and MLC(20): alpha-actin ratios were reduced compared to myometria of non-pregnant women. In contrast, h-caldesmon was up-regulated in pregnancy resulting in an elevated h-caldesmon: alpha-actin ratio. There were, however, no further significant changes in ROK alpha, MLC(20) or h-caldesmon expression with spontaneous or oxytocin-induced labour. These data suggest that the mechanism(s) integrating myometrial signalling events with the onset of human labour does not involve differential alterations of the cellular expressions of caveolins, ROK, alpha-actin, MLC(20) or h-caldesmon.

Implantation site intermediate trophoblasts in placenta cretas

Placenta cretas are defined as abnormal adherences or ingrowths of placental tissue, but their pathogenetic mechanism has not been fully explained. During histologic examination of postpartum uteri, we noticed that the number of implantation site intermediate trophoblasts was increased in the placental bed of placenta cretas. To validate our observation and to address the pathogenetic role of implantation site intermediate trophoblasts in placenta cretas, we examined postpartum uteri with placenta cretas (n=34) and noncretas (n=22), obtained from Cesarean or immediate postpartum hysterectomy specimens. Using antibody to CD146, a marker for implantation site intermediate trophoblasts, we found that placenta cretas had significantly thicker layer of implantation site intermediate trophoblasts (2300+/-1200 mum) than noncretas (1500+/-1200 microm, P<0.025). We also observed that the confluent distribution of cells was more frequent in placenta cretas (97%) than noncretas samples (45%, P<0.001), and that the total number of implantation site intermediate trophoblasts within the superficial myometrium of the placental bed was significantly higher in placenta cretas than noncretas. Using antibodies to Ki-67, Bcl-2 and cleaved caspase-3 to determine the proliferative index and apoptotic rates of implantation site intermediate trophoblasts, we found that they were close to zero in both groups and did not differ significantly. These findings suggest that the increased number of implantation site intermediate trophoblasts observed in placenta cretas may be related to the pathogenesis of placental ingrowth, but the mechanism by which the increase in implantation site intermediate trophoblasts causes placenta cretas remains to be clarified.

Human myometrial adaptation to pregnancy: cDNA microarray gene expression profiling of myometrium from non-pregnant and pregnant women

The human uterus undergoes profound physiological tissue remodelling during pregnancy. In the myometrium, altered gene expression must underlie these extensive molecular and structural changes. The purpose of this study was to compare expression profiles of pregnant and non-pregnant myometrium, in order to identify genes that participate in this process. mRNA from 14 non-pregnant and four pregnant human myometrial samples were analysed using a human UniGEM V microarray with 7075 cDNA elements. A total of 602 transcripts from the microarray were up-regulated >/=2.0-fold in pregnant myometrium, with 37 transcripts up-regulated >/=4.0-fold. In contrast, eight transcripts were down-regulated >/=2.0-fold in pregnancy. To ensure accurate representation of differential gene expression, Northern blot analyses using total RNA from 16 samples of non-pregnant and pregnant myometrium were used to examine mRNA levels for four of the genes that were differentially expressed by microarray analysis, namely plasminogen activator inhibitor type 1 (PAI-1), milk fat globule-EGF factor 8 protein (MFGE8), secreted frizzled-related protein 4 (sFRP4) and estrogen receptor alpha (ERalpha). On the microarray these transcripts were up-regulated 7.5-fold for PAI-1 and 4.9-fold for MFGE8 in pregnant myometrium, and down-regulated 3.7-fold for sFRP4 and 2.9-fold for ERalpha in pregnancy. Northern blot analyses confirmed these changes. Our findings suggest that microarray technology is a useful tool for examining global changes in gene expression that occur as the myometrium differentiates from non-pregnant to pregnant status. Defining these changes provides new insight into the structural and functional adaptations of human myometrium during pregnancy.

Labour is associated with increased expression of type-IIA secretory phospholipase A2 but not type-IV cytosolic phospholipase A2 in human myometrium

Human labour is associated with increased prostaglandin synthesis within the uterus. The aim of this study was to examine the expression of the type-IV cytosolic phospholipase A2 (cPLA2-IV) and the type IIA secretory phospholipase A2 (sPLA2-IIA) in myometrium in association with labour onset at term and preterm deliveries. These enzymes are important for the release of the prostaglandin precursor, arachidonic acid, from phospholipid membrane stores. RT-PCR was used to determine differences in gene expression between non-labour and labour groups. Expression of sPLA2-IIA in human myometrium was significantly increased with pregnancy, and with labour, both at term and preterm. Expression of cPLA2-IV in myometrium was not significantly altered with respect to pregnancy or labour. Immunohistochemical analysis demonstrated differences in the spatial localization of cPLA2-IV and sPLA2-IIA protein in upper and lower segment myometrium. cPLA2-IV was predominantly in vascular endothelial cells, while sPLA2-IIA was observed in vascular, endothelial and smooth muscle cells. In addition, sPLA2-IIA showed a distinct nuclear or perinuclear localization in myometrial smooth muscle cells of the lower segment. We postulate that the increased expression of sPLA2-IIA rather than cPLA2-IV in the myometrium may play a role in the onset and/or maintenance of human parturition.

[Establishment of two-dimensional electrophoresis of uterine leiomyoma for the proteome analysis]

OBJECTIVE

To establish and optimize the two-dimensional electrophoresis (2-DE) of uterine leiomyoma for the proteome analysis.

METHODS

Run immobilized pH gradient (IPG)-isoelectric focusing electrophoresis as the first dimension, then vertical SDS-PAGE electrophoresis as the second dimension. A series of important steps,such as sample solubility, volume of loading, electrophoresis parameters and protocol for staining were optimized.

RESULTS

The 2-DE patterns of uterine leiomyoma and myometrium with good quality were obtained.

CONCLUSION

With optimal condition the two-dimensional electrophoresis of uterine leiomyoma can be obtained.

Expression of estrogen receptors alpha and beta in term human myometrium

We used immunohistochemistry to compare the expression of estrogen receptors (ERalpha and ERbeta) in term myometria of 32 pregnant women divided in two groups. Group I comprised of 16 women in labour and group II included 16 non-laboring gravidas. We observed cytoplasmatic localization of both ER isoforms and no differences in the ER expression between the two groups of patients. The abundance and specific localization of ERs in human term myometrium seems to be independent of its contractile activity which may point to the specific role of those receptors in late pregnancy myometrium.