Granulysin, a T cell product, kills bacteria by altering membrane permeability

Granulysin, a protein located in the acidic granules of human NK cells and cytotoxic T cells, has antimicrobial activity against a broad spectrum of microbial pathogens. A predicted model generated from the nuclear magnetic resonance structure of a related protein, NK lysin, suggested that granulysin contains a four alpha helical bundle motif, with the alpha helices enriched for positively charged amino acids, including arginine and lysine residues. Denaturation of the polypeptide reduced the alpha helical content from 49 to 18% resulted in complete inhibition of antimicrobial activity. Chemical modification of the arginine, but not the lysine, residues also blocked the antimicrobial activity and interfered with the ability of granulysin to adhere to Escherichia coli and Mycobacterium tuberculosis. Granulysin increased the permeability of bacterial membranes, as judged by its ability to allow access of cytosolic ss-galactosidase to its impermeant substrate. By electron microscopy, granulysin triggered fluid accumulation in the periplasm of M. tuberculosis, consistent with osmotic perturbation. These data suggest that the ability of granulysin to kill microbial pathogens is dependent on direct interaction with the microbial cell wall and/or membrane, leading to increased permeability and lysis.

A stationary-phase stress-response sigma factor from Mycobacterium tuberculosis

Alternative RNA polymerase sigma factors are a common means of coordinating gene regulation in bacteria. Using PCR amplification with degenerate primers, we identified and cloned a sigma factor gene, sigF, from Mycobacterium tuberculosis. The deduced protein encoded by sigF shows significant similarity to SigF sporulation sigma factors from Streptomyces coelicolor and Bacillus subtilis and to SigB, a stress-response sigma factor, from B. subtilis. Southern blot surveys with a sigF-specific probe identified cross-hybridizing bands in other slow-growing mycobacteria, Mycobacterium bovis bacille Calmette-Guérin (BCG) and Mycobacterium avium, but not in the rapid-growers Mycobacterium smegmatis or Mycobacterium abscessus. RNase protection assays revealed that M. tuberculosis sigF mRNA is not present during exponential-phase growth in M. bovis BCG cultures but is strongly induced during stationary phase, nitrogen depletion, and cold shock. Weak expression of M. tuberculosis sigF was also detected during late-exponential phase, oxidative stress, anaerobiasis, and alcohol shock. The specific expression of M. tuberculosis sigF during stress or stationary phase suggests that it may play a role in the ability of tubercle bacilli to adapt to host defenses and persist during human infection.

Inhaled fluticasone in bronchiectasis: a 12 month study

BACKGROUND

The clinical efficacy of inhaled corticosteroid (ICS) treatment has not been evaluated in bronchiectasis, despite the presence of chronic airway inflammation.

METHODS

After three consecutive weekly visits, 86 patients were randomised to receive either fluticasone 500 mug twice daily (n = 43, 23F, mean (SD) age 57.7 (14.4) years) or matched placebo (n = 43, 34F, 59.2 (14.2) years) and reviewed regularly for 52 weeks in a double blind fashion.

RESULTS

35 and 38 patients in the fluticasone and placebo groups completed the study. Significantly more patients on ICS than on placebo showed improvement in 24 hour sputum volume (OR 2.5, 95% CI 1.1 to 6.0, p = 0.03) but not in exacerbation frequency, forced expiratory volume in 1 second, forced vital capacity, or sputum purulence score. Significantly more patients with Pseudomonas aeruginosa infection receiving fluticasone showed improvement in 24 hour sputum volume (OR 13.5, 95% CI 1.8 to 100.2, p = 0.03) and exacerbation frequency (OR 13.3, 95% CI 1.8 to 100.2, p = 0.01) than those given placebo. Logistic regression models revealed a significantly better response in sputum volume with fluticasone treatment than with placebo among subgroups of patients with 24 hour sputum volume <30 ml (p = 0.04), exacerbation frequency </=2/year (p = 0.04), and sputum purulence score >5 (p = 0.03).

CONCLUSIONS

ICS treatment is beneficial to patients with bronchiectasis, particularly those with P. aerurginosa infection.

Coronary revascularization with or without cardiopulmonary bypass in patients with preoperative nondialysis-dependent renal insufficiency

BACKGROUND

Preoperative renal insufficiency is a predictor of acute renal failure in patients undergoing conventional coronary artery bypass grafting. Off-pump coronary artery bypass operations have been shown to reduce renal dysfunction in patients with normal renal function, but the effect of this technique in patients with preoperative nondialysis-dependent renal insufficiency is unknown.

METHODS

From June 1996 to December 1999, data of 3,250 consecutive patients undergoing coronary artery bypass grafting were prospectively entered into the Patient Analysis & Tracking Systems (PATS, Dendrite Clinical Systems, London, UK). Two hundred and fifty-three patients with preoperative serum creatinine more than 150 micromol/L were identified (202 patients on-pump, 51 patients off-pump), and clinical outcomes were analyzed. Serum creatinine and urea, in-hospital mortality, and morbidity were compared between groups. The association of perioperative factors with acute renal failure was investigated by multiple logistic regression analysis.

RESULTS

Preoperative characteristics were similar between the groups. Mean number of grafts was 2.9 +/- 0.8 and 2.3 +/- 0.8 in the on-pump and off-pump groups, respectively (p < 0.0001). Comparison between groups showed a significantly higher incidence of stroke, inotropic requirement, blood loss, and transfusion of red packed cell and platelets in the on-pump group (all p < 0.05). Postoperative serum creatinine and urea were higher in the on-pump group with a significant difference at 12 hours postoperatively (p < 0.05). Logistic regression analysis identified cardiopulmonary bypass, serum creatinine level 60 hours postoperatively, inotropic requirement, need for intraaortic balloon pump, transfusion of red packed cell, and hours of ventilation as predictors of postoperative acute renal failure.

CONCLUSIONS

This study suggests that off-pump coronary artery bypass operations reduce in-hospital morbidity and the likelihood of acute renal failure in patients with preoperative nondialysis-dependent renal insufficiency undergoing myocardial revascularization.

Neutrophil adhesion molecule expression during cardiopulmonary bypass with bubble and membrane oxygenators

The neutrophil-mediated tissue injury associated with cardiopulmonary bypass (CPB) is thought to require the interaction of specific neutrophil and endothelial adhesion molecules. In this study, the effects of CPB on the expression of neutrophil CD11b and CD18 (the components of the Mac-1 adhesion molecule) were examined; the effects of membrane versus bubble oxygenators on the expression of neutrophil CD11b and CD18 were compared; and the plasma levels of the intercellular adhesion molecule-1 (cICAM-1), an inducible endothelial adhesion molecule, were measured. In addition, the time courses of complement activation and neutrophil granule release were measured to determine their temporal relationship to the expression of the neutrophil adhesion molecule. Fifteen adult patients underwent procedures requiring cardiopulmonary bypass; hollow-fiber membrane oxygenators were used in 8 (group M) and bubble oxygenators were used in 7 (group B). Blood samples were drawn before, during, and after CPB for determination of the expression of neutrophil CD11b and CD18 (immunofluorescent flow cytometry), and the plasma cICAM-1, elastase, lactoferrin (enzyme-linked immunoabsorbent assay), and plasma C3a (radioimmunoassay) levels. CPB caused an immediate and sustained increase in the neutrophil CD11b and CD18 expression in both groups; after 60 minutes of CPB, CD11b expression had increased by 116.9% +/- 19.1% in group B and by 79.3% +/- 8.5% in group M (p = 0.78). Over the same period, CD18 expression increased by 97.2% +/- 17.9% in group B and by 72.4% +/- 16.8% in group M (p = 0.67).(ABSTRACT TRUNCATED AT 250 WORDS)

Exposure to antibiotics induces expression of the Mycobacterium tuberculosis sigF gene: implications for chemotherapy against mycobacterial persistors

The sigF gene encodes an alternate sigma factor found in Mycobacterium tuberculosis and related pathogenic mycobacteria. Determination of conditions of sigF expression is an important step in understanding the conditional gene regulation which may govern such processes as virulence and dormancy in mycobacteria. We constructed an in-frame translational lacZ-kan fusion within the sigF gene to determine the conditions of sigF expression. This reporter construct was expressed from a multicopy plasmid in a strain of BCG harboring an integrated luciferase reporter gene under the control of the mycobacteriophage L5 gp71 promoter. Antibiotic exposure, in particular, ethambutol, rifampin, streptomycin, and cycloserine treatment, increased the level of SigF reporter specific expression in a dose-dependent fashion. The level of SigF reporter specific expression increased over 100-fold in late-stationary-phase growth compared to that in exponential growth. During the exponential phase, SigF specific expression could be induced by a number of other stresses. Anaerobic metabolism induced SigF by greater than 150-fold, particularly in the presence of metronidazole. Cold shock increased the level of SigF specific expression, while heat shock decreased it. Oxidative stress was also an important inducer of SigF specific expression; a greater induction was seen with cumene hydroperoxide than with hydrogen peroxide. Comparisons of bacterial viability as determined by the luciferase assay or by plating serial dilutions revealed that luciferase gp71-dependent activity was an unreliable predictor of the numbers of CFU during stationary-phase growth and anaerobic metabolism. The induction of sigF following antibiotic exposure suggests that this bacterial transcription factor may control genes which are important for mycobacterial persistence in the host during chemotherapy.

N-(fluorenyl-9-methoxycarbonyl) amino acids, a class of antiinflammatory agents with a different mechanism of action

Several members of a series of N-(fluorenyl-9-methoxycarbonyl) amino acids were found to possess a broad spectrum of antiinflammatory activity. The compounds were active against oxazolone dermatitis in mice and adjuvant arthritis in rats, models in which activated T lymphocytes are implicated. The compounds also inhibited T-lymphocyte activation in vitro, assessed by using the mixed lymphocyte reaction. The compounds inhibited the reversed passive Arthus reaction in rats and arachidonic acid-induced dermatitis in mice, models in which leukocyte infiltration is responsible for the inflammatory reaction. More complete evaluation was made of one compound, N-(fluorenyl-9-methoxycarbonyl)leucine (NPC 15199). On histologic examination after arachidonic acid administration, NPC 15199 was found to block recruitment of neutrophils into the inflammatory site. The compound was not a general myelotoxin. Prolonged treatment of animals did not alter bone-marrow progenitor number or the numbers of circulating white blood cells. Further, several white cell functions were not inhibited in vitro, including neutrophil respiratory burst and macrophage phagocytosis. NPC 15199 was effective in blocking antigen arthritis in rabbits and was effective in a therapeutic protocol, reversing oxazolone edema. These studies suggest that N-(fluorenyl-9-methoxycarbonyl) amino acids may be valuable therapeutic agents for inflammatory diseases.

Asian Indian women: knowledge, attitudes and behaviors toward breast cancer early detection

Education programs have been developed to promote adherence to recommended breast cancer screening guidelines. Few studies have assessed the degree to which ethnic subgroups are perceiving and acting on the proffered information. Such assessment is vital to the creation of efficient public health interventions. This paper describes the reported breast cancer knowledge, attitudes, and screening behaviors of 194 American Asian Indian women. While monthly breast self exam adherence was low, only 40.7%, 61.3% of women 40 and older, and 70% of women 50 and older, reported having had a mammogram within the past 12 months. These rates for annual mammography screening are high relative to many other ethnic groups. While the results are encouraging, the respondents may not be representative of all Asian Indian women. The majority of these women reported that their breast cancer knowledge is inadequate. They were willing to be called upon to share with others any knowledge they gained. There is a clear opportunity for public health nurses to provide Asian Indian women with a more comprehensive understanding of breast health and disease. Those women can then share their health knowledge with other women within their ethnic group.

The Staphylococcus aureus rsbW (orf159) gene encodes an anti-sigma factor of SigB

SigB, a newly discovered alternative sigma factor of Staphylococcus aureus, has been shown to play an important role in stress responses and the regulation of virulence factors. The rsbW (orf159) gene is immediately upstream of sigB. Its gene product is homologous to Bacillus subtilis RsbW which under appropriate conditions binds to B. subtilis SigB and functions as an anti-sigma factor or negative posttranslational regulator. To define the function of S. aureus RsbW, both the S. aureus SigB and RsbW proteins were expressed in Escherichia coli and purified. Cross-linking experiments with these purified proteins revealed that RsbW was capable of specific binding to SigB. In an in vitro transcription runoff assay, RsbW prevented SigB-directed transcription from the sar P3 promoter, a known SigB-dependent promoter, and the inhibitory activity of RsbW was found to be concentration dependent. We also identified SigB promoter consensus sequences upstream of the genes encoding alkaline shock protein 23 and coagulase and have demonstrated SigB and RsbW dependence for the promoters in vitro. These results show that RsbW is a protein sequestering anti-sigma factor of S. aureus SigB and suggest that SigB activity in S. aureus is regulated posttranslationally.

Post-transcriptional stimulation of the assembly and secretion of triglyceride-rich apolipoprotein B lipoproteins in a mouse with selective deficiency of brown adipose tissue, obesity, and insulin resistance

A mouse model of insulin resistance and its associated dyslipidemia was generated by crossing mice expressing human apolipoprotein B (apoB) with mice lacking only brown adipose tissue (BATless). On a high fat diet, male apoB/BATless mice became obese, hypercholesterolemic, hypertriglyceridemic, and hyperinsulinemic compared with control apoB mice. Fast performance liquid chromatography revealed increased triglyceride concentrations in intermediate density lipoprotein/low density lipoprotein (LDL) and reduced high density lipoprotein cholesterol concentrations. Inhibition of lipolysis by the drug, tetrahydrolipostatin, demonstrated that very low density lipoprotein-sized particles were initially secreted. Metabolic studies employing Triton WR-1339 and either [(3)H]glycerol or [(3)H]palmitate showed that the hypertriglyceridemia in apoB/BATless mice was due to the increased synthesis and secretion of triglyceride. Furthermore, lipoprotein lipase and hepatic lipase activities were not defective. ApoB was also secreted at increased rates in the apoB/BATless mice. Similar levels of apoB mRNA in apoB and apoB/BATless mice indicated that apoB secretion was regulated post-transcriptionally. LDL receptor mRNA was increased in the apoB/BATless mice, indicating that the observed increase in apoB-lipoprotein secretion was not due to their decreased reuptake. Finally, mRNA levels of the large subunit of microsomal triglyceride transfer protein, a required component for very low density protein assembly, were not different between apoB and apoB/BATless mice. This rodent model should prove useful in exploring mechanisms underlying the regulation of apoB secretion in the context of insulin resistance.

Mycobacterium tuberculosis sigF is part of a gene cluster with similarities to the Bacillus subtilis sigF and sigB operons

The Mycobacterium tuberculosis (MTB) SigF alternate sigma factor has been shown to have significant homology to the Bacillus subtilis (BSU) stress-response sigma factor, SigB, as well as to the BSU developmental sigma factor, SigF. In this study we report that like both the BSU sigB and sigF genes, MTB sigF is preceded by an open reading frame (usfX) encoding a protein with significant homology to the previously described BSU anti-sigma factors, RsbW and SpollAB. Sequence analysis suggests that the usfX and sigF genes appear to be cotranscribed and translationally coupled. A second open reading frame called usfY precedes usfX, but has no significant homologues and may not be contranscribed with the usfX and sigF. The sigF gene has been overexpressed in Escherichia coli, purified, and used to raise polyclonal antibodies. Immunoblotting demonstrates that MTB SigF is antigenically closer to BSU SigB than to BSU SigF. Fusion of the MTB sigF gene to the MTB hsp60 promoter has demonstrated that inappropriate overexpression of sigF is lethal for the slow-grower Mycobacterium bovis bacille Calmette-Guérin (BCG), but not for the rapid-grower Mycobacterium smegmatis which lacks a sigF homologue. Hence, sigF, encoding an MTB stress response, stationary phase transcription factor, is preceded by an antisigma factor homologue and is incompatible with growth when constitutively overexpressed in BCG.

Impact of mentor guidance in surgical career selection

PURPOSE

The aim of this study was to survey graduates of a university general surgical residency training program to determine factors that influenced their selection of a specialty field.

METHODS

A 39-item questionnaire was mailed to 86 graduates of a university general surgery program who matriculated from 1975 to 1989. The impact of lifestyle, technology, clinical opportunity, and mentor guidance in the residents' selection of a specialty field and eventual clinical practice was assessed. Results were analyzed using Fisher's Exact test with significance determined at P less than.05.

RESULTS

The response rate was 65% (56 of 86). Eighty percent of respondents identified the most important aspect influencing their choice of specialty was interest in that field; additional factors included perception of prestige, presence of clinical opportunity, mentor influence, and family priorities. Sixty-six percent of respondents chose the same career as their mentor, attributing this to the mentor's skill (n = 36, 68%), achievements (n = 35, 66%), and verbal recommendations about their specialty field (n = 24, 45%), p < 0.05.

CONCLUSIONS

Surgical residents use many criteria in selecting a field of specialty with mentor guidance an important component. Knowledge of these influential areas should help training programs offer appropriate career guidance. J Pediatr Surg 36:1802-1804.

Color selection with a hygromycin-resistance-based Escherichia coli-mycobacterial shuttle vector

Hygromycin-resistance (HyR)-based Escherichia coli-mycobacterial shuttle plasmids have high efficiencies of transformation and a broad mycobacterial host range. We have introduced a lacZ alpha (encoding the alpha-polypeptide fragment of beta-galactosidase (beta Gal))-multiple cloning site cassette into a HyR-based shuttle vector to generate a plasmid with nine unique cloning sites and the added feature of beta Gal color selection in appropriate E. coli host strains.

Human estrogen receptor beta-specific monoclonal antibodies: characterization and use in studies of estrogen receptor beta protein expression in reproductive tissues

Investigation of the role of the second, more recently described estrogen receptor, denoted ERbeta, will be critical in understanding the molecular mechanisms underlying tissue-specific gene regulation by estrogens. Expression of ERbeta in a variety of tissues has been examined predominantly at the mRNA level, and there is little information regarding the cellular localization and size of the endogenous ERbeta protein, due, in part, to the limited availability of human ERbeta-specific antibodies. Thus, our aim was to generate specific antibodies to human ERbeta and use them to determine the tissue-specific distribution and size(s) of the ERbeta protein. To this end, we have cloned three different hybridoma cell lines that produce monoclonal antibodies specific for the hormone-binding domain of human ERbeta. The antibodies, made in mice against human ERbeta amino acids 256-505 (hormone binding domain lacking the F domain), are designated CFK-E12 (E12), CMK-A9 (A9) and CWK-F12 (F12) and were determined to be the IgG gamma1 isotype for E12, and IgG gamma2b for A9 and F12. All three monoclonal antibodies could be used to detect in vitro translated, baculovirus expressed, and cell transfected and expressed ERbeta protein by Western blot analyses, and all failed to detect ERalpha. A9 and F12 were able to immunoprecipitate efficiently the native form of ERbeta protein in the presence and absence of estradiol. Epitope mapping studies indicate that the E12 and F12 antibodies recognize overlapping peptide sequences in the N-terminal region of the hormone-binding domain, a region that is highly conserved among species. Immunocytochemical studies with these antibodies reveal nuclear-specific localization of the ERbeta protein in granulosa cells of the rat ovary. Nuclear ERbeta is also specifically localized in epithelial and some stromal cells of mouse and rat epididymis. Western blot analysis with protein extracts from ovarian granulosa cells of human, rat, mouse, and pig showed a ca. 52 kDa and an additional ca. 62-64 kDa band in these species. These results indicate the presence of two predominant molecular size forms of the ERbeta protein in ovarian granulosa cells and demonstrate the utility of these antibodies for detection of ERbeta in the human and in several other mammalian species.

Distribution of proteins between nucleus and cytoplasm of Amoeba proteus

By transplanting nuclei between labeled and unlabeled cells, we determined the localization of the major proteins of amebas and described certain features of their intracellular distributon. We identified approximately 130 cellular proteins by fluorography of one-dimensional polyacrylamide electrophoretic gels and found that slightly less than half of them (designated NP, for nuclear proteins) are almost exclusively nuclear. About 95 percent of the other proteins (designated CP for cytoplamsic proteins) are roughly equally concentrated in nucleus and cytoplasm, but-because the cytoplasm is 50 times larger than the nucleus-about 98 percent of each of the latter is in the cytoplasm. Of the CP, roughly 5 percent are not detectable in the nucleus. Assuming that these are restricted to the cytoplasm only because, for example, they are in structures too large to enter the nucleus and labeled CP readily exit a nucleus introduced into unlabeled cytoplasm, we conclude that the nuclear envelope does not limit the movement of any nonstructural cellular protein in either direction between the two compartments. Some NP are not found in the cytoplasm (although ostensibly synthesized there) presumably because of preferential binding within the nucleus. Almost one half of the protein mass in nuclei in vivo is CP and apparently only proteins of that group are lost from nuclei when cells are lysed. Thus, while an extracellular environment allows CP to exit isolated nuclei, the nuclear binding affinities for NP are retained. Further examination of NP distribution shows that many NP species are, in fact, detectable in the cytoplasm (although at only about 1/300 the nuclear concentration), apparently because the nuclear affinity is relatively low. These proteins are electrophoretically distinguishable from the high-affinity NP not found in the cytoplasm. New experiments show that an earlier suggestion that the nuclear transplantation operation causes an artifactual release of NP to the cytoplasm is largely incorrect. Moreover, we show that cytoplasmic "contamination" of nuclear preparations is not a factor in classifying proteins by these nuclear transplantation experiments. We speculate the no mechanism has evolved to confine most CP to the cytoplasm (where they presumably function exclusively) because the cytoplasm's large volume ensures that CP will be abundant there. Extending Bonner's idea of "quasi-functional nuclear binding sites" for NP, we suggest that a subset of NP usually have a low affinity for available intranuclear sites because their main function(s) occurs at other intranuclear sites to which they bind tightly only when particular metabolic conditions demand. The other NP (those completely absent from cytoplasm) presumable always are bound with high affinity at their primary functional sites.

Structural analysis of two genes encoding divergent forms of yeast cytochrome c oxidase subunit V

In Saccharomyces cerevisiae, subunit V of the inner mitochondrial membrane protein complex cytochrome c oxidase is encoded by two nonidentical genes, COX5a and COX5b. Both genes are present as single copies in S. cerevisiae and in several other Saccharomyces species. Nucleotide sequencing studies with the S. cerevisiae COX5 genes reveal that they encode proteins of 153 and 151 amino acids, respectively. Overall, the coding sequences of COX5a and COX5b have nucleotide and protein homologies of 67 and 66%, respectively. They are saturated for nucleotide substitutions that result in a synonomous codon, indicating a long divergence time between these two genes. Nucleotide sequences flanking the COX5a and COX5b coding regions exhibit no significant homology. The COX5a protein, pre-subunit Va, contains a 20-amino-acid leader peptide, whereas the COX5b protein, pre-subunit Vb, contains a 17-amino-acid leader peptide. These two leader peptides exhibit only 45% homology in the primary sequence, but have similar predicted secondary structures. By analyzing the RNA transcripts from both genes we have found that COX5a is a contiguous gene but that COX5b contains an intron. Surprisingly, the COX5b intron interrupts the AUG codon that initiates translation of the pre-subunit Vb polypeptide and contains a 5' donor splice sequence that differs from that normally found in yeast introns.

Role of progesterone receptor activation in pituitary adenylate cyclase activating polypeptide gene expression in rat ovary

It is well known that the pituitary gonadotropin surge induces progesterone receptor (PR) gene expression in luteinizing granulosa cells and that PR activation is critical for successful ovulation. To further understand the molecular mechanism(s) by which PR plays a role critical for granulosa cell functions, we wanted to identify progesterone-induced genes in granulosa cells. We employed a PCR-based subtraction cloning strategy to screen for genes expressed differentially in granulosa cells that were challenged with forskolin in the presence of progesterone or ZK98299. One such differentially expressed clone was identified as the pituitary adenylate cyclase activating polypeptide (PACAP). To begin to understand the relationship between PR activation and PACAP gene expression in luteinizing granulosa cells, we examined whether PR and PACAP messenger RNA (mRNA) expression is temporally correlated. In cultured granulosa cells, both human CG and forskolin induced PR and PACAP mRNA levels in a dose-dependent manner, as determined by semi-quantitative RT-PCR assays. However, the peak expression for PR and PACAP mRNAs was observed at 3 h and 6 h after hormone treatment, respectively. This time difference in cAMP-responsive expression of the PR and PACAP genes is due, at least in part, to the requirement of ongoing protein synthesis for PACAP expression, as demonstrated by the inhibitory effect of cycloheximide on cAMP-induced PACAP, but not PR, mRNA levels. To determine whether PR synthesis is prerequisite for PACAP expression, we examined the effect of ZK98299, a specific PR antagonist, on cAMP-induced PACAP mRNA expression. This compound blocked cAMP-induced PACAP mRNA expression in a dose-dependent manner, indicating that PR activation is required for PACAP gene expression in granulosa cells. We then compared cellular localization and hormonal regulation of ovarian PR and PACAP gene expression in immature rats treated with gonadotropins as well as in adult rats during the preovulatory period by using in situ hybridization and semiquantitative RT-PCR assays. Results show that both PR and PACAP mRNAs are induced in granulosa cells of preovulatory follicles by human CG, but that the PR gene is expressed before the PACAP gene. Taken together, these results demonstrate that PRs mediate the LH-induced PACAP gene expression in rat granulosa cells.

Progesterone receptor activation mediates LH-induced type-I pituitary adenylate cyclase activating polypeptide receptor (PAC(1)) gene expression in rat granulosa cells

We have previously reported that the pituitary adenylate cyclase activating polypeptide (PACAP) gene is regulated in ovarian granulosa cells by the autocrine and/or paracrine interaction between progesterone and its nuclear receptor progesterone receptor (PR). To initiate studies on the functional significance of the progesterone-induced PACAP production in luteinizing granulosa cells, we sought to determine the expression and hormonal regulation of PACAP receptors in the rat ovary. The relative mRNA levels of three known PACAP receptor subtypes (PAC(1), VPAC(1), and VPAC(2)) were determined in ovaries of immature rats treated with gonadotropins, by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) assays. Results show that all PAC(1), VPAC(1), and VPAC(2) transcripts are expressed at a detectable level in immature rat ovaries. Importantly, the ovarian level of PAC(1), but not VPAC(1) or VPAC(2), mRNA notably changes during gonadotropin challenges. Ovarian PAC(1) mRNA expression decreases during the pregnant mare's serum gonadotropin (PMSG)-induced follicular phase but substantially increases during the human chorionic gonadotropin (hCG)-induced periovulatory period. Because the hCG-induced increase in ovarian PAC(1) mRNA expression is attributable to the hormone-induced PAC(1) mRNA expression in granulosa cells of the preovulatory follicles, we next examined whether hCG regulates PAC(1) mRNA expression by directly acting on granulosa cells. When granulosa cells isolated from PMSG (40 h)-primed immature rats were challenged with hCG (or forskolin), PAC(1), but not VPAC(1) or VPAC(2), mRNA expression significantly increased within 6 h. Because the LH-induced PAC(1) mRNA expression (6 h) proceeds PR activation (3 h) in granulosa cells as the LH-induced PACAP mRNA expression (6 h) does, we further determined the cause-effect relationship among LH, PR activation and PAC(1) receptor gene expression, by examining the effect of PR antagonist, ZK98299, on the ability of LH to increase PAC(1) mRNA levels in luteinizing granulosa cells. Results show that ZK98299 inhibited the stimulatory effect of hCG (or forskolin) on PAC(1) mRNA expression, at the level of all known splice variants of PAC(1) mRNA in granulosa cells. In summary, our results demonstrating that PR activation is critical for the LH-induced PAC(1) gene expression in luteinizing granulosa cells suggest that PR activation regulates the finely tuned expression of the PACAP/PACAP receptor genes in luteinizing granulosa cells and thus dictates the timing of the autocrine and/or paracrine function of PACAP in preovulatory follicles.