Human INHBB Gene Variant (c.1079T>C:p.Met360Thr) Alters Testis Germ Cell Content, but Does Not Impact Fertility in Mice

Testicular-derived inhibin B (α/β B dimers) acts in an endocrine manner to suppress pituitary production of follicle-stimulating hormone (FSH), by blocking the actions of activins (β A/B/β A/B dimers). Previously, we identified a homozygous genetic variant (c.1079T>C:p.Met360Thr) arising from uniparental disomy of chromosome 2 in the INHBB gene (β B-subunit of inhibin B and activin B) in a man suffering from infertility (azoospermia). In this study, we aimed to test the causality of the p.Met360Thr variant in INHBB and testis function. Here, we used CRISPR/Cas9 technology to generate InhbbM364T/M364T mice, where mouse INHBB p.Met364 corresponds with human p.Met360. Surprisingly, we found that the testes of male InhbbM364T/M364T mutant mice were significantly larger compared with those of aged-matched wildtype littermates at 12 and 24 weeks of age. This was attributed to a significant increase in Sertoli cell and round spermatid number and, consequently, seminiferous tubule area in InhbbM364T/M364T males compared to wildtype males. Despite this testis phenotype, male InhbbM364T/M364T mutant mice retained normal fertility. Serum hormone analyses, however, indicated that the InhbbM364T variant resulted in reduced circulating levels of activin B but did not affect FSH production. We also examined the effect of this p.Met360Thr and an additional INHBB variant (c.314C>T: p.Thr105Met) found in another infertile man on inhibin B and activin B in vitro biosynthesis. We found that both INHBB variants resulted in a significant disruption to activin B in vitro biosynthesis. Together, this analysis supports that INHBB variants that limit activin B production have consequences for testis composition in males.

Low miR-143/miR-145 Cluster Levels Induce Activin A Overexpression in Oral Squamous Cell Carcinomas, Which Contributes to Poor Prognosis

Deregulated expression of activin A is reported in several tumors, but its biological functions in oral squamous cell carcinoma (OSCC) are unknown. Here, we investigate whether activin A can play a causal role in OSCCs. Activin A expression was assessed by qPCR and immunohistochemistry in OSCC tissues. Low activin A-expressing cells were treated with recombinant activin A and assessed for apoptosis, proliferation, adhesion, migration, invasion and epithelial-mesenchymal transition (EMT). Those phenotypes were also evaluated in high activin A-expressing cells treated with follistatin (an activin A antagonist) or stably expressing shRNA targeting activin A. Transfections of microRNA mimics were performed to determine whether the overexpression of activin A is regulated by miR-143/miR-145 cluster. Activin A was overexpressed in OSCCs in comparison with normal oral mucosa, and high activin A levels were significantly associated with lymph node metastasis, tumor differentiation and poor survival. High activin A levels promoted multiple properties associated with malignant transformation, including decreased apoptosis and increased proliferation, migration, invasion and EMT. Both miR-143 and miR-145 were markedly downregulated in OSCC cell lines and in clinical specimens, and inversely correlated to activin A levels. Forced expression of miR-143 and miR-145 in OSCC cells significantly decreased the expression of activin A. Overexpression of activin A in OSCCs, which is controlled by downregulation of miR-143/miR-145 cluster, regulates apoptosis, proliferation and invasiveness, and it is clinically correlated with lymph node metastasis and poor survival.

Contribution of corneal neovascularization to dendritic cell migration into the central area during human corneal infection

Compared with the peripheral corneal limbus, the human central cornea lacks blood vessels, which is responsible for its immunologically privileged status and high transparency. Dendritic cells (DCs) are present in the central avascular area of inflamed corneas, but the mechanisms of their migration to this location are poorly understood. Here, we investigated the contribution of vessel formation to DC migration into the central cornea, and analyzed the DC chemotactic factors produced by human corneal epithelial (HCE) cells. Using human eyes obtained from surgical procedures, we then assessed vessel formation, DC distribution, and activin A expression immunohistochemically. The results demonstrated increased numbers of vessels and DCs in the central area of inflamed corneas, and a positive correlation between the number of vessels and DCs. Activin A was expressed in the subepithelial space and the endothelium of newly formed blood vessels in the inflamed cornea. In infected corneas, DCs were present in the central area but no vascularization was observed, suggesting the presence of chemotactic factors that induced DC migration from the limbal vessels. To test this hypothesis, we assessed the migration of monocyte-derived DCs toward HCE cell supernatants with or without lipopolysaccharide (LPS) stimulation of HCE cells and inflammatory cytokines (released by HCE cells). DCs migrated toward tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, and activin A, as well as LPS-stimulated HCE cell supernatants. The supernatant contained elevated TNF-α, IL-6, and activin A levels, suggesting that they were produced by HCE cells after LPS stimulation. Therefore, vessels in the central cornea might constitute a DC migration route, and activin A expressed in the endothelium of newly formed vessels might contribute to corneal vascularization. Activin A also functions as a chemotactic factor, similar to HCE-produced TNF-α and IL-6. These findings enhance our understanding of the pathophysiology of corneal inflammation during infection.

[Low expression of activin A in mouse and human embryonic teratocarcinoma cells]

TGFP3 family factors play an important role in regulating the balance of self-renewal and differentiation of mouse and human pluripotent stem and embryonic teratocarcinoma cells. The expression patterns of TGFbeta family signaling ligands and functional roles of these signaling pathways differ significantly in mouse and human embryonic stem cells, but the activity and functional role of these factors in mouse and human embryonic teratocarcinoma cells were not sufficiently investigated. Comparative quantitative real-time PCR analysis of the expression of TGF@[beta] family factors in mouse embryonic stem, embryonic germ, and embryonic teratocarcinoma cells showed that embryonic teratocarcinoma cells express lower ActivinA than pluripotent stem cells but similar levels of factors Nodal, Lefty 1, TGFbeta1, BMP4, and GDF3. In human nullipotent embryonic teratocarcinoma PA-1 cells, most factors of the TGFbeta family (ACTIVINA, NODAL, LEFTY 1, BMP4, and GDF3) are expressed at lower levels than in human embryonic stem cells: Thus, in mouse and human nullipotent teratocarcinoma cells, theexpression of ActivinA is significantly reduced com- pared ivith embryonic stem cells. Presumably, these differences may be associated with changes in the functional activity of the respective signaling pathways and deregulation of proliferative and antiproliferative mechanisms in embryonic teratocarcinoma cells.

Activin A as a mediator of NK-dendritic cell functional interactions

The interaction of NK cells with dendritic cells (DCs) results in reciprocal cell activation through the interaction of membrane proteins and the release of soluble factors. In this article, we report that in NK-DC cocultures, among a set of 84 cytokines investigated, activin A was the second highest induced gene, with CXCL8 being the most upregulated one. Activin A is a member of the TGF-β superfamily and was previously shown to possess both proinflammatory and anti-inflammatory activities. In NK-DC cocultures, the induction of activin A required cell contact and was dependent on the presence of proinflammatory cytokines (i.e., IFN-γ, TNF-α, and GM-CSF), as well as on NK cell-mediated DC killing. CD1(+) DCs were the main activin A producer cells among myeloid blood DC subsets. In NK-DC cocultures, inhibition of activin A by follistatin, a natural inhibitory protein, or by a specific blocking Ab, resulted in the upregulation of proinflammatory cytokine release (i.e., IL-6, IL-8, TNF-α) by DCs and in the increase of DC maturation. In conclusion, our study reports that activin A, produced during NK-DC interactions, represents a relevant negative feedback mechanism that might function to prevent excessive immune activation by DCs.

Effects of activin A on survival, function and gene expression of pancreatic islets from non-diabetic and diabetic human donors

Emerging evidence suggests that activin with its associated receptors, second messengers, and antagonists would be excellent targets for therapeutic drug development in the treatment of diabetes. We undertook the current study to investigate the ability to extrapolate findings from rodent studies to human islets in which data thus far has been scarce. We tested the hypothesis that human islets synthesize activin and that activin participates in the regulation of islet β-cells. Human islets from 33 separate isolations were categorized based on functional status, culture status and diabetic status. Statistical comparisons were made by ANOVA with Tukey post-hoc adjustment for multiple comparisons. Experiments investigating activin utilized qPCR, FACS cell sorting, immunofluorescent antibody staining, functionality assays, viability assays and protein secretion assays. We have defined the transcript expression patterns of activin and the TGFβ superfamily in human islets. We found INHBA (the gene encoding activin A) to be the most highly expressed of the superfamily in normal, cultured islets. We elucidated a link between the islet microenvironment and activin A. We found differential ligand expression based on diabetic, culture and functional status. Further, this is also the first report that links direct effects of activin A with the ability to restore glucose-stimulated insulin secretion in human islets from type 2 diabetic donors thereby establishing the relevance of targeting activin for therapeutic drug development.

Activin A is stimulated by tumor necrosis factor-alpha and modulates collagen gene expression in human amniotic cells

BACKGROUND

Accumulating evidence supports the idea of activin A as a modulator of inflammation. In human pregnancy, elevated activin A concentrations in amniotic fluid are reported in women with intra-amniotic infection and inflammation- induced pre-term birth.

AIM

To test the hypothesis that activin A was involved in the pathophysiology of amnionitis, we evaluated the effects of tumor necrosis factor-α and lipopolysaccharide on activin A production in human amniotic epithelial cells, and the effects of activin A on the expression of collagen mRNA in amniotic mesenchymal cells.

MATERIALS AND METHODS

Amniotic membranes were obtained from patients without systemic disease, signs of premature delivery or fetal complications, during elective cesarean sections at term. Amniotic epithelial cells and mesenchymal cells were separately obtained by enzymatic digestion and cultured. Activin A was measured by enzyme-linked immunosorbent assay and collagen mRNA levels were assessed by quantitative PCR.

RESULTS

Amniotic epithelial cells produced activin A in a cell density- and time-dependent manner. Tumor necrosis factor- α enhanced activin A production in a time-dependent (48-120 h) and dose-dependent (10-300 ng/ml) manner in amniotic epithelial cells. Lipopolysaccharide also stimulated activin A production, but the effect was less prominent. In amniotic mesenchymal cells, the effect of activin A on the expression of type I and type III collagen mRNA was suppressive.

CONCLUSIONS

Tumor necrosis factor-α and lipopolysaccharide stimulated activin A production in amniotic epithelial cells, and activin A modulated expression of collagen mRNA in amniotic mesenchymal cells. These results support the idea that activin A is involved in the pathophysiology of amnionitis.

Expression of inhibin/activin proteins and receptors in the human hypothalamus and basal forebrain

The inhibin/activin family of proteins is known to have a broad distribution of synthesis and expression in many species, as well as a variety of functions in reproductive and other physiological systems. Yet, our knowledge regarding the production and function of inhibin and activin in the central nervous system is relatively limited, especially in humans. The present study aimed to explore the distribution of inhibin/activin protein subunits and receptors in the adult human brain. The human hypothalamus and surrounding basal forebrain was examined using post-mortem tissues from 29 adults. Immunocytochemical studies were conducted with antibodies directed against the inhibin/activin α, βA, and βB subunits, betaglycan and the activin type IIA and IIB receptors. An immunoassay was also utilised to measure dimeric inhibin A and B levels in tissue homogenates of the infundibulum of the hypothalamus. Robust βA subunit immunoreactivity was present in the paraventricular, supraoptic, lateral hypothalamic, infundibular, dorsomedial and suprachiasmatic nuclei of the hypothalamus, in the basal ganglia, and in the nucleus basalis of Meynert. A similar staining distribution was noted for the βB subunit, betaglycan and the type II receptor antibodies, whereas α subunit staining was not detected in any of the major anatomical regions of the human brain. Inhibin B immunoreactivity was present in all tissues, whereas inhibin A levels were below detectable limits. These studies show for the first time that the inhibin/activin protein subunits and receptors can be co-localised in the human brain, implicating potential, diverse neural functions.

Altered gonadal expression of TGF-β superfamily signaling factors in environmental contaminant-exposed juvenile alligators

Environmental contaminant exposure can influence gonadal steroid signaling milieus; however, little research has investigated the vulnerability of non-steroidal signaling pathways in the gonads. Here we use American alligators (Alligator mississippiensis) hatched from field-collected eggs to analyze gonadal mRNA transcript levels of the activin-inhibin-follistatin gene expression network and growth differentiation factor 9. The eggs were collected from Lake Woodruff National Wildlife Refuge, a site with minimal anthropogenic influence, and Lake Apopka, a highly contaminated lake adjacent to a former EPA Superfund site. The hatchling alligators were raised for 13 months under controlled conditions, thus limiting differences to embryonic origins. Our data reveal sexually dimorphic mRNA expression in 13-month-old alligator gonads similar to patterns established in vertebrates with genetic sex determination. In addition, we observed a relationship between lake of origin and mRNA expression of activin/inhibin subunits α and βB, follistatin, and growth differentiation factor 9. Our study suggests that embryonic exposure to environmental contaminants can affect future non-steroidal signaling patterns in the gonads of a long-lived species.

Generation of a specific activin antagonist by modification of the activin A propeptide

Elevated activin A levels in inhibin-deficient mice promote the development of gonadal tumors and induce cachexia by reducing muscle, liver, stomach, and fat mass. Because activin A is an important regulator of tissue growth, inhibiting the actions of this TGFβ family ligand may halt or reverse pathology in diseased tissues. In this study, we modified the activin A propeptide to generate a specific activin antagonist. Propeptides mediate the synthesis and secretion of all TGFβ ligands and, for some family members (e.g. TGFβ1), bind the mature growth factor with high enough affinity to confer latency. By linking the C-terminal region of the TGFβ1 propeptide to the N-terminal region of the activin A propeptide, we generated a chimeric molecule [activin/TGFβ1 propeptide (AT propeptide)] with increased affinity for activin A. The AT propeptide was 30-fold more potent than the activin A propeptide at suppressing activin-induced FSH release by LβT2 pituitary gonadotrope cells. Binding of the AT propeptide to activin A shields the type II receptor binding site, thereby reducing Smad2 phosphorylation and downstream signaling. In comparison with the commonly used activin antagonists, follistatin (IC(50) 0.42 nM), soluble activin type II receptor A-Fc (IC(50) 0.47 nM), and soluble activin type II receptor B-Fc (IC(50) 0.91 nM), the AT propeptide (IC(50) 2.6 nM) was slightly less potent. However, it was more specific, inhibiting activin A and activin B (IC(50) 10.26 nM) but not the closely related ligands, myostatin and growth differentiation factor-11. As such, the AT propeptide represents the first specific activin antagonist, and it should be an effective reagent for blocking activin actions in vivo.

Beneficial effects of follistatin in hepatic ischemia-reperfusion injuries in rats

BACKGROUND

Ischemia-reperfusion injury has been demonstrated in a variety of clinical settings. The morbidity associated with liver transplantation and major hepatic resections is partly a result of ischemia-reperfusion injury. Follistatin, an activin-binding protein, binds to activins and subsequently blocks their action. It was reported that blockade of the action of activin with administration of follistatin accelerates recovery from ischemia renal injury. This study was conducted to investigate the involvement of the activin-follistatin system in hepatic ischemia-reperfusion injury.

METHODS

Total hepatic ischemia for 30 min was performed followed by reperfusion in a rat model. Rats were divided into two groups: a follistatin group and a control group. Follistatin (1 μg/body), which is an activin-binding protein, was administered at the time of reperfusion.

RESULTS

Though 80% of animals survived in the follistatin group, four of five animals died in the control group within 3 days after reperfusion (p<0.05). AST was significantly lower at 3 h after reperfusion in the follistatin group (p<0.05). LDH was also lower at 6 h after reperfusion in the follistatin group (p<0.05). Follistatin inhibited the mRNA expression of the βA subunit of activin. Moreover, the expression of IL-6, which is an inflammatory cytokine, was suppressed at 6 h after reperfusion in the follistatin group (p<0.05).

CONCLUSIONS

The present study demonstrated that treatment with follistatin reduced the expression of IL-6 and activin resulting in beneficial support for hepatic ischemia-reperfusion injuries.

Regulation of inhibin/activin expression in rat early antral follicles

The aim of the present study was to determine the endocrine activity of cultured early antral follicles (EAF) isolated from prepubertal diethylstilbestrol-treated rats. The effect of steroidogenic substrates and FSH on steroid, inhibin A and B, Pro-alphaC and activin A production was evaluated. Androsterone was the predominant steroid produced by EAF. The addition of androstenedione, androstenedione+FSH and progesterone stimulated oestradiol production, whereas 25-hydroxycholesterol (25-OH-Chol) increased progesterone production. Inhibin A, B, Pro-alphaC, and activin A were produced under basal conditions. The predominance of inhibin B over inhibin A was not affected by the addition of androstenedione or progesterone. Inhibin A and activin A production was stimulated by FSH. 25-OH-Chol increased Inha, Inhba and Inhbb mRNA expression and the production of the three molecular forms of inhibins but decreased activin A production. These results show that FSH and the steroid follicular microenvironment differentially modulate the gene expression of inhibin/activin subunits, their assembly and secretion.

The neuroprotective effect of Activin A and B: implication for neurodegenerative diseases

Activin is a member of the transforming growth factor-beta superfamily which comprises a growing list of multifunctional proteins that function as modulators of cell proliferation, differentiation, hormone secretion and neuronal survival. This study examined the neuroprotective effect of both Activin A and B in serum withdrawal and oxidative stress apoptotic cellular models and investigated the expression of pro- and anti-apoptotic proteins, which may account for the mechanism of Activin-induced neuroprotection. Here, we report that recombinant Activin A and B are neuroprotective against serum deprivation- and toxin- [either the parkinsonism-inducing neurotoxin, 6-hydroxydopamine (6-OHDA) or the peroxynitrite donor, 3-(4-morpholinyl) sydnonimine hydrochloride (SIN-1)] induced neuronal death in human SH-SY5Y neuroblastoma cells. Furthermore, we demonstrate for the first time that transient transfection with Activin betaA or betaB significantly protect SH-SY5Y and rat pheochromocytoma PC12 cells against serum withdrawal-induced apoptosis. This survival effect is mediated by the Bcl-2 family members and involves inhibition of caspase-3 activation; reduction of cleaved poly-ADP ribose polymerase and phosphorylated H2A.X protein levels and elevation of tyrosine hydroxylase expression. These results indicate that both Activin-A and -B share the potential to induce neuroprotective activity and thus may have positive impact on aging and neurodegenerative diseases to retard the accelerated rate of neuronal degeneration.

Follistatin rescues the inhibitory effect of activin A on the differentiation of bovine preadipocyte

We investigated the effect of activin A and follistatin on the differentiation of bovine preadipocytes. Stromal-vascular (SV) cells containing preadipocytes were prepared from perirenal adipose tissue of approximately 30-month-old Japanese Black steers. After confluence, differentiation was induced by 1-methyl-3-isobutyl-xanthine, dexamethasone, insulin and troglitasone for 2 days, and then subsequently cultured for 6 days. The cells were treated with activin A during the induction of differentiation (the early phase of differentiation) or throughout the differentiation period. We measured the terminal differentiation markers such as glycerol-3-phosphate dehydrogenase (GPDH) activity, lipid accumulation, and the expression of adipocyte fatty acid-binding protein mRNA at the end of cultures. Activin A suppressed the induction of all differentiation markers regardless of the duration of treatment. The treatment with activin A also reduced the expression of peroxisome proliferator-activated receptor (PPAR) gamma and CCAAT/enhancer binding protein (C/EBP) alpha mRNAs without affecting the expression of C/EBPbeta mRNA. We also observed that follistatin completely rescued the inhibitory effect of activin A on bovine preadipocyte differentiation. Furthermore, the higher doses of follistatin increased GPDH activity even in the presence of activin A compared with the cells treated with neither activin A nor follistatin. Additionally, the SV cells expressed activin A and myostatin mRNAs. These results suggest that activin A inhibits bovine preadiopocyte differentiation via affecting transcriptional cascade upstream of PPARgamma and C/EBPalpha expressions, and that follistatin suppresses the inhibitory effect of activin A on bovine preadipocyte differentiation. Endogenous activin A and/or myostatin possibly inhibit the differentiation of bovine preadipocytes.

Inhibition of allergen-induced airway remodeling in Smad 3-deficient mice

Intracellular signaling pathways that converge on Smad 3 are used by both TGF-beta and activin A, key cytokines implicated in the process of fibrogenesis. To determine the role of Smad 3 in allergen-induced airway remodeling, Smad 3-deficient and wild-type (WT) mice were sensitized to OVA and challenged by repetitive administration of OVA for 1 mo. Increased levels of activin A and increased numbers of peribronchial TGF-beta1(+) cells were detected in WT and Smad 3-deficient mice following repetitive OVA challenge. Smad 3-deficient mice challenged with OVA had significantly less peribronchial fibrosis (total lung collagen content and trichrome staining), reduced thickness of the peribronchial smooth muscle layer, and reduced epithelial mucus production compared with WT mice. As TGF-beta and Smad 3 signaling are hypothesized to mediate differentiation of fibroblasts to myofibroblasts in vivo, we determined the number of peribronchial myofibroblasts (Col-1(+) and alpha-smooth muscle actin(+)) as assessed by double-label immunofluorescence microscopy. Although the number of peribronchial myofibroblasts increased significantly in WT mice following OVA challenge, there was a significant reduction in the number of peribronchial myofibroblasts in OVA-challenged Smad 3-deficient mice. There was no difference in levels of eosinophilic airway inflammation or airway responsiveness in Smad 3-deficient compared with WT mice. These results suggest that Smad 3 signaling is required for allergen-induced airway remodeling, as well as allergen-induced accumulation of myofibroblasts in the airway. However, Smad 3 signaling does not contribute significantly to airway responsiveness.

Expression of HPV, steroid receptors (ERalpha, ERbeta, PR-A and PR-B) and inhibin/activin subunits (alpha, betaA and betaB) in adenosquamous endometrial carcinoma

AIM

The aim of the study was to determine possible pathogenetic factors and molecules which may be used as tumor markers of adenosquamous endometrial carcinoma.

MATERIALS AND METHODS

Eight adenosquamous endometrial carcinomas were immunohistochemically tested with specific monoclonal antibodies for HPV (polyclonal anti-HPV and monoclonal anti-HPV 18), estrogen receptors ER-alpha and ER-beta, progesterone receptors PR-A and PR-B and the inhibin/activin subunits inhibin-alpha, -betaA and -betaB.

RESULTS

HPV 18 and the polyclonal HPV antibody was detected in all adenosquamous endometrial carcinomas, both in the endometrioid (n = 7/8) and squamous (n = 8/8) parts of the tumor. Neither ER-alpha or ER-beta were detectable in any tumor, in contrast to PR-A and PR-B which were detected in about half of these tumors (PR-A: n = 5/8 and PR-B: n = 2/8). Inhibin-alpha and -betaB were not detected, while inhibin-betaA was expressed in all adenosquamous carcinomas.

CONCLUSION

The carcinogenesis of adenosquamous endometrial carcinomas was associated with HPV infection. Adenosquamous endometrial carcinomas seem not to be controlled by estrogens. The absence of the expression of the inhibin-alpha subunit suggests a tumor-suppressive function in adenosquamous endometrial tumors. The absence of the expression of the inhibin-betaB subunit, which is probably a marker of differentiation, points to the malignancy of these tumors. The other inhibin subunit, inhibin-betaA, was expressed in all adenosquamous tumors. It remains to be clarified if these parameters can be used as tumor markers.

Inhibin/activin subunits are immunohistochemically expressed in complete and partial hydatidiform moles

BACKGROUND AND AIM

Inhibins are dimeric glycoproteins, belonging to the transforming growth factor beta (TGF-beta) family, composed of an alpha-subunit (INH-alpha) and one of two possible beta-subunits (betaA or betaB). Additionally two further beta-subunits (betaC and betaE) have been cloned, although their function remains still quite unclear. The detection by immunohistochemistry of inhibin/activin subunits has been proposed as a useful marker of trophoblastic diseases. Interestingly, a complete mole cannot be easily differentiated from a partial mole. Therefore, the aim of this study was to determine expression changes of the five inhibin/activin subunits in partial and complete moles.

MATERIALS AND METHODS

Histologically diagnosed complete (n = 6) and partial (n = 3) hydatidiform moles were immunohistochemical analyzed for INH-alpha, INH-betaA, INH-betaB, INH-betaC and INH-betaE subunits. The immunohistochemical reaction in intermediate trophoblast was analyzed with a semiquantitative score (IRS) and statistical analysis was performed.

RESULTS

Immuno-histochemical reaction with INH-alpha, INH-betaA, INH-betaB, INH-betaC and INH-betaE subunits was demonstrated in hydatidiform moles. The INH-betaA and INH-betaB expression was significantly higher in complete compared to partial moles (p < 0.05 each), while INH-alpha, INH-betaC and INH-betaE did not demonstrate any statistically significant differences.

CONCLUSION

We demonstrated an immunohistochemical expression of all five inhibin/activin subunits in partial and complete hydatidiform moles. The expression of INH-betaA and INH-betaB determined immunohistochemically was significantly up-regulated in complete moles, suggesting the utilization of these antibodies as diagnostic differentiation markers between complete and partial moles.

The immunohistochemical expression of the inhibin/activin subunits is up-regulated by interferon-beta1a in Ishikawa cell line

BACKGROUND

Inhibins are dimeric glycoproteins belonging to the TGF-beta1 family and are composed of an a-subunit (INH-alpha) and one of two possible beta-subunits (betaA or betaB; INH-betaA and INH-betaB). They have a substantial function in human reproduction and also seem to play an important role in endocrine-responsive tumors. Interestingly, there is an association between interferon and TGF-beta expression. However, this relationship has not been assessed in endometrial tissue regarding inhibin/activin expression. Therefore, the aim of this study was to determine expression changes of inhibin/activin subunits in the endometrial Ishikawa carcinoma cell line after stimulation with interferon-beta1a.

MATERIALS AND METHODS

The Ishikawa cell line was cultured until confluence was observed (after 2 days). After adding interferon-beta1a (1000 IE/ml) Ishikawa cells were immunohistochemical analyzed for INH-alpha, INH-betaA and INH-betaB subunits. Experiments were performed in triplicates. The immunohistochemical expression was analyzed with a semiquantitative score (IRS) and statistical analysis was performed.

RESULTS

Immunohistochemical reaction with INH-alpha could not be demonstrated in unstimulated cells, while it was significantly up-regulated in interferon-stimulated cells (p < 0.02). INH-betaA and INH-betaB were primarily observed during the mitotic phases of unstimulated cells. After stimulation their expression was significantly higher (p < 0.05 each) compared to controls and could be observed not only during mitotic phases but also in nonmitotic cells.

CONCLUSION

For the first time, we demonstrated a functional relationship between interferon and inhibin/activin subunits. The expression of INH-alpha, INH-betaA and INH-betaB were immunohistochemical significantly up-regulated in the Ishikawa endometrial cell line after stimulation with interferon-beta1a. Since INH-alpha is thought to be tumor suppressive in the mouse model, interferon-beta1a might activate its gene. It remains to be clarified if this effect can be used as therapeutic options in endometrial carcinomas.

Changes in extracellular activin A:follistatin ratio during differentiation of a mesenchymal progenitor cell line, ROB-C26 into osteoblasts and adipocytes

We investigated the effects of BMP-2 and dexamethasone (Dex) on follistatin (FS) and activin A expressions in a mesenchymal progenitor cell line, ROB-C26 (C26). C26 cells stimulated to differentiate into osteoblastic cells by blocking myogenic differentiation after BMP-2 treatment and into adipocytes with Dex treatment. Alkaline phosphatase (ALP) mRNA expression and its activity in the confluent C26 cells were dose- and time-dependently stimulated by BMP-2, but inhibited by Dex. The stimulatory effect on FS and activin A mRNA expressions by BMP-2 and Dex were dose-dependent. Cycloheximide pre-treatment indicated that FS and activin A expressions appear to be the direct target of BMP-2 and Dex signaling. BMP-2 time-dependently increased FS and activin A levels. Dex also increased FS level, but induced a time-dependent biphasic effect on activin A level, a decrease (2-6 h) followed by an increase (12-72 h). The data of the ratio of activin A concentration in the culture media to that of FS (activin A:FS ratio) measured by ELISA showed that BMP-2-induced osteoblastic differentiation involved an activin-dominant microenvironment, whereas Dex-induced adipocyte differentiation involved a FS-dominant microenvironment. Excess FS suppressed the stimulatory ALP activity of BMP-2, whereas activin A prevented not only Dex-induced inhibitory ALP activity, but also adipogenesis via suppression of the adipocyte transcriptional factor cascade. These results indicate that BMP-2-induced activin-dominant microenvironment may be critical for osteoblastic differentiation by restricting the antagonistic effects of FS on BMP activity, while Dex-induced FS-dominant microenvironment may be critical for adipocyte differentiation by restricting the inhibitory action of activin A on adipocyte differentiation.

The role of the activin system in keloid pathogenesis

Keloid scars represent a pathological response to cutaneous injury under the regulation of many growth factors. Activin-A, a dimeric protein and a member of the transforming growth factor-β superfamily, has been shown to regulate various aspects of cell growth and differentiation in the repair of the skin mesenchyme and the epidermis. Thus our aim was to study the role of activin and its antagonist, follistatin, in keloid pathogenesis. Increased mRNA expression for activin was observed in keloid scar tissue by performing RNase protection assay. Immunohistochemistry showed increased localization of both activin-A and follistatin in the basal layer of epidermis of keloid tissue compared with normal tissue. ELISA demonstrated a 29-fold increase in concentration of activin-A and an ∼5-fold increase in follistatin in conditioned media in keloid fibroblasts compared with normal fibroblasts. Although keloid keratinocytes produced 25% more follistatin than normal keratinocytes, the amounts of activin-A, in contrast, was ∼77% lower. Proliferation of fibroblasts was stimulated when treated with exogenous activin-A (46% increase in keloids fibroblasts) or following co-culture with hβAHaCaT cells (66% increase). Activin-A upregulated key extracellular matrix components, namely collagen, fibronectin, and α-smooth muscle actin, in normal and keloid fibroblasts. Co-treatment of follistatin with activin-A blocked the stimulatory effects of activin on extracellular matrix components. These findings emphasize the importance of the activin system in keloid biology and pathogenesis and suggest a possible therapeutic potential of follistatin in the prevention and treatment of keloids.

Activin and glucocorticoids synergistically activate follicle-stimulating hormone beta-subunit gene expression in the immortalized LbetaT2 gonadotrope cell line

FSH is produced by the pituitary gonadotrope to regulate gametogenesis. Production of the beta-subunit of FSH is the rate-limiting step in FSH synthesis, and a number of peptide and steroid hormones within the reproductive axis have been found to regulate transcription of the FSH beta-subunit gene. Although both activin and glucocorticoids are notable regulators of FSHbeta by themselves, we find that cotreatment results in a synergistic interaction on the mouse FSHbeta promoter at the level of the gonadotrope using transient transfection of a reporter gene into the LbetaT2 immortalized gonadotrope-derived cell line. This synergistic interaction is specific to FSHbeta, because only additive effects of these two hormones are observed on LH beta-subunit, GnRH receptor, and mouse mammary tumor virus gene expression. Components of both activin and glucocorticoid signaling are found to be necessary for synergy, and there are specific cis elements on the mouse FSHbeta promoter that contribute to the synergistic response as well. We also identify novel activin-responsive regions in the mouse FSHbeta promoter and find that the -120 site can bind Smad2/3 in vitro. In addition, the glucocorticoid receptor and Smad3 are sufficient to confer a striking synergy with glucocorticoids on the mouse FSHbeta promoter. Our studies provide the first evidence of a synergistic interaction between activin and glucocorticoids within the gonadotrope cell and demonstrate that this synergy can occur directly at the level of the mouse FSHbeta promoter.

Activin A functions as a Th2 cytokine in the promotion of the alternative activation of macrophages

Activin A, a member of the TGF-beta superfamily, is a pluripotent growth and differentiation factor. In this study, we report that murine Th cells produce activin A upon activation. Activin activity in the cultured CD4+ T cells was induced by anti-CD3 cross-linking. Activin betaA mRNA level was increased in response to activation, indicating that activin production in CD4+ T cells is regulated at the mRNA level. Activin production was detected exclusively in CD4+CD25- T cells, but not in CD4+CD25+ regulatory T cells. When CD4+ T cells were differentiated into Th cell subsets, higher activin secretion was detected when cultured under Th2-skewing conditions. The mRNA level of activin betaA was abundant in Th2, but not in Th1 cells. Furthermore, secretion of activin was significantly higher in activated Th2 clones than in Th1 clones. The activin betaA-proximal promoter contains a binding site for c-Maf, a Th2-specific transcriptional factor, at close proximity with an NF-AT binding site. c-Maf was able to synergize with NF-AT to transactivate activin betaA gene, and both factors are implicated in activin betaA transcription in Th2 cells. Activin A induced macrophages to express arginase-1 (M-2 phenotype), whereas it inhibited inducible NO synthase expression (M-1 phenotype) induced by IFN-gamma. Taken together, these observations suggest that activin A is a novel Th2 cytokine that promotes differentiation of macrophages toward the M-2 phenotype.

Oocyte-secreted factor activation of SMAD 2/3 signaling enables initiation of mouse cumulus cell expansion

Expansion of the mouse cumulus-oocyte complex (COC) is dependent on oocyte-secreted paracrine factors. Transforming growth factor beta (TGFB) superfamily molecules are prime candidates for the cumulus expansion-enabling factors (CEEFs), and we have recently determined that growth differentiation factor 9 (GDF9) alone is not the CEEF. The aim of this study was to examine oocyte paracrine factors and their signaling pathways that regulate mouse cumulus expansion. Using RT-PCR, oocytes were found to express the two activin subunits, Inhba and Inhbb, and activin A and activin B both enabled FSH-induced cumulus expansion of oocytectomized (OOX) complexes. Follistatin, an activin-binding protein, neutralized activin-induced expansion but had no effect on oocyte-induced expansion. The type I receptors for GDF9 and activin are activin receptor-like kinase 5 (ALK5) and ALK4, respectively, both of which activate the same SMAD 2/3 signaling pathway. We examined the requirement for this signaling system using an ALK 4/5/7 inhibitor, SB-431542. SB-431542 completely ablated FSH-stimulated GDF9-, activin A-, activin B-, and oocyte-induced cumulus expansion. Moreover, SB-431542 also antagonized epidermal growth factor-stimulated, oocyte-induced cumulus expansion. Using real-time RT-PCR, SB-431542 also attenuated GDF9-, activin A-, and oocyte-induced OOX expression of hyaluronan synthase 2, tumor necrosis factor alpha-induced protein 6, prostaglandin synthase 2, and pentraxin 3. This study provides evidence that the CEEF is composed of TGFB superfamily molecules that signal through SMAD 2/3 to enable the initiation of mouse cumulus expansion.

Regulated production of activin A and inhibin B throughout the cycle of the seminiferous epithelium in the rat

Production and regulation of activin A and inhibin B during the cycle of the seminiferous epithelium were investigated in adult rats. Immunohistochemistry localised the activin beta(A)-subunit to the Sertoli cell cytoplasm, with much weaker expression in spermatocytes and spermatids. Both activin A and inhibin B, measured by ELISA were secreted by, seminiferous tubule fragments over 72 h in culture. Activin A was secreted in a cyclic manner with peak secretion from tubules isolated at stage VIII. Tubules collected during stage VI produced the least activin A. Inhibin B secretion was highest from stage IX-I tubules and lowest from stage VII tubules. Addition of interleukin-1beta (IL-1beta) had relatively little effect on activin A or inhibin B secretion in culture. In contrast, the peak secretion of activin A by stage VIII tubules was blocked by co-incubation with an excess of human recombinant IL-1 receptor antagonist, whereas inhibin B secretion increased slightly. Dibutyryl cAMP stimulated activin A secretion by late stage VII and VIII tubules and stimulated inhibin B across all stages. These data indicate that activin A and inhibin B are cyclically regulated within the seminiferous epithelium, with endogenous IL-1 (presumably IL-1alpha produced by the Sertoli cells), responsible for a peak of activin A production subsequent to sperm release at stage VIII. These data provide direct evidence that production of activin A and inhibin B by the Sertoli cell is locally modulated by IL-1alpha , in addition to FSH/cAMP, under the influence of the developing spermatogenic cells.

Expression of inhibins, activins, insulin-like growth factor-I and steroidogenic enzymes in the equine placenta

In this study, the expression patterns of inhibins, activins, insulin-like growth factor-I (IGF-I) and steroidogenic enzymes in equine placentae recovered during the latter two-thirds of gestation were examined. Concentrations of inhibin A and inhibin pro-alphaC in endometrial and fetal placental tissue homogenates were very low during the period examined, whereas these tissues contained high concentrations of activin A. In both maternal endometrial and fetal placental tissues, activin A levels decreased as pregnancy progressed. Expression of inhibin alpha-subunit was not observed in the placenta using either immunohistochemistry or in situ hybridization. Inhibin/activin betaA-subunit and its mRNA were confined to maternal endometrial glands, whereas immunopositive betaB-subunit was not detected in either endometrial glands or microcotyledons. Cytochrome P450 side chain cleavage enzyme was detected by immunohistochemistry in both endometrial glands and microcotyledons, whereas cytochrome P450 17alpha-hydroxylase/lyase was absent in these tissues. Immunopositive signals for 3beta-hydroxysteroid dehydrogenase and cytochrome P450 aromatase were localized in microcotyledons but not in endometrial glands. Immunohistochemistry revealed that IGF-I was highly expressed in microcotyledons around Day 130, and decreased as pregnancy progressed. Changes in the expression of IGF-I were correlated with the number of PCNA positive cells in the placenta. The present study demonstrated the presence and localized the site of expression of activin, IGF-I and steroidogenic enzymes in equine placental tissues during the latter two-thirds of gestation; the results suggest that activin and IGF-I may be involved in the regulation of placental development.

Dissociation of Angiogenesis and Tumorigenesis in Follistatin- and Activin-Expressing Tumors

The transforming growth factor-beta superfamily member activin and its antagonist, follistatin, act as a pleiotropic growth factor system that controls cell proliferation, differentiation, and apoptosis. Activin inhibits fibroblast growth factor 2-induced sprouting angiogenesis in vitro (spheroidal angiogenesis assay) and in vivo (Matrigel assay). To further study the role of the activin/follistatin system during angiogenesis and tumor progression, activin- and follistatin-expressing R30C mammary carcinoma cells were studied in mouse tumor experiments. Surprisingly, activin-expressing tumors grew much faster than follistatin-expressing tumors although they failed to induce increased angiogenesis (as evidenced by low microvessel density counts). Conversely, follistatin-expressing tumors were much smaller but had a dense network of small-diameter capillaries. Qualitative angioarchitectural analyses (mural cell recruitment, perfusion) revealed no major functional differences of the tumor neovasculature. Analysis of activin- and follistatin-expressing R30C cells identified a cell autonomous role of this system in controlling tumor cell growth. Whereas proliferation of R30C cells was not altered, follistatin-expressing R30C cells had an enhanced susceptibility to undergo apoptosis. These findings in experimental tumors are complemented by an intriguing case report of a human renal cell carcinoma that similarly shows a dissociation of angiogenesis and tumorigenesis during tumor progression. Collectively, the data shed further light into the dichotomous stimulating and inhibiting roles that the activin/follistatin system can exert during angiogenesis and tumor progression. Furthermore, the experiments provide a critical proof-of-principle example for the dissociation of angiogenesis and tumorigenesis, supporting the concept that tumor growth may not be dependent on increased angiogenesis as long as a minimal intratumoral microvessel density is maintained.

Mechanism delineating differential effect of an antiestrogen, tamoxifen, on the serum LH and FSH in adult male rats

Tamoxifen, a synthetic non-steroidal antiestrogen with residual estrogenic activity, administered to adult male rats reduces their fertility. A decrease in the circulating LH and testosterone levels with a transient rise or no change in circulating FSH levels was observed. The present study was carried out to delineate the mechanism causing the differential effect of tamoxifen on circulating gonadotropins by correlating it to changes in the hypothalamic LHRH, pituitary gonadotropins and testicular inhibin/activin. Hypothalamus, pituitary-hypothalamus complex (PHC) and intact pituitary (PI) from control and tamoxifen-treated male rats were superfused in vitro, and pulsatile release of LHRH by hypothalamus and that of LH and FSH by the PHC and PI were studied. Concomitantly, testicular immunoexpression of alpha and betaB subunits of inhibin/activin were studied by immunohistochemistry and enzyme-linked immunosorbent assays (ELISA). At 0.4 mg/kg/day dose of tamoxifen a decrease in mean hypothalamic LHRH and LH pulse frequency from PHC construct was observed. FSH pulse frequency was not affected under the same experimental conditions. At the same dose of tamoxifen, testicular expression of both alpha and betaB subunits of inhibin/activin was upregulated. The study demonstrated that reduced circulating LH levels were due to a decrease in hypothalamic LHRH concentration and in LH pulsatility following tamoxifen treatment. The lack of effect on circulating FSH under the same experimental conditions was likely due to its modulation by inhibin and activin.

Activin-A secretion is increased in the eutopic endometrium from women with essndometriosis

BACKGROUND

Activin is a well-characterised growth and differentiation factor and an important inflammatory mediator. Activin is secreted by normal endometrial glands and stroma and is expressed by endometrial leucocytes. It is also known that the eutopic endometrium from women with endometriosis is functionally different to that from women without endometriosis. In this study, we hypothesise that the endometrial secretion of activin is altered in women with endometriosis.

AIMS

To determine whether the expression of inhibin/activin subunits and the secretion of activin-A is different in eutopic endometrium from women with and without endometriosis.

METHODS

Endometrial biopsies were obtained from premenopausal, regularly menstruating women with and without endometriosis. Staining intensity for the different inhibin/activin subunits was compared in endometrial and endometriotic biopsies. Activin-A secretion was studied using endometrial explants and endometrial glandular and stromal monolayer cell cultures.

RESULTS

The alpha- and betaA-subunits of inhibin/activin were more abundant in eutopic glandular cells from patients with minimal to mild endometriosis compared to women without endometriosis. In patients with endometriosis, the betaB-subunit was more abundant in eutopic stromal cells and endometrial leucocytes. Comparison of paired endometrial and endometriotic biopsies from the same patient did not reveal significant differences for any of the inhibin/activin subunits or activin receptors. Activin-A secretion by glandular and stromal endometrial cells was sevenfold and threefold higher, respectively, in women with endometriosis compared to women without endometriosis.

CONCLUSIONS

The expression of inhibin/activin subunits in eutopic endometrium is altered in women with endometriosis, leading to higher levels of activin-A secretion by both glandular cells and stromal cells.

Regulation of baboon fetal ovarian folliculogenesis by estrogen

Although it is well established that formation of the pool of follicles available for ovarian function and fertility in adulthood in human and non human primates occurs in utero, our understanding of the regulation of fetal ovarian development is incomplete. Our laboratories have been instrumental in establishing the baboon as a model for the study of human reproductive endocrinology and showed that estrogen plays a central integrative role in regulating fetal-placental development. Therefore, we adapted our baboon model to study the role of estrogen on fetal ovarian development. Estrogen receptors alpha and beta were expressed in pregranulosa cells and interfollicular nests of the baboon fetal ovary. In baboons in which estrogen levels had been suppressed by administration of an aromatase inhibitor throughout the second half of gestation, fetal ovarian follicle numbers were reduced by 50%, whereas the number of interfollicular nests comprised of oocytes and pregranulosa cells was increased. The decrease in follicles in estrogen-deprived animals was associated with a marked upregulation of expression of alpha-inhibin, but not activins or activin receptors and signaling molecules. Moreover, the majority of the follicles formed in ovaries of estrogen-depleted fetuses appeared unhealthy and contained oocytes with a marked reduction/depletion in microvilli, structures essential for uptake of substrates from surrounding granulosa cells. We propose that estrogen regulates fetal ovarian folliculogenesis and formation of healthy oocytes by controlling the intraovarian activin:inhibin ratio and the development of oocyte microvilli. These findings demonstrate a need for translational research studies of the impact of impairment of estrogen action/availability on reproductive function in adulthood.

Activin A Mediates Growth Inhibition and Cell Cycle Arrest through Smads in Human Breast Cancer Cells

The transforming growth factor-beta (TGF-beta) superfamily of growth factors is responsible for a variety of physiologic actions, including cell cycle regulation. Activin is a member of the TGF-beta superfamily that inhibits the proliferation of breast cancer cells. Activin functions by interacting with its type I and type II receptors to induce phosphorylation of intracellular signaling molecules known as Smads. Smads regulate transcription of many genes in a cell- and tissue-specific manner. In this study, the role of activin A in growth regulation of breast cancer cells was investigated. Activin stimulated the Smad-responsive promoter, p3TP, 2-fold over control in T47D breast cancer cells. Activin inhibited cellular proliferation of T47D breast cancer cells after 72 hours, an effect that could be abrogated by incubation with the activin type I receptor inhibitor, SB431542. Activin arrested T47D cells in the G0-G1 cell cycle phase. Smad2 and Smad3 were phosphorylated in response to activin and accumulated in the nucleus of treated T47D cells. Infection of T47D cells with adenoviral Smad3 resulted in cell cycle arrest and activation of p3TP-luciferase, whereas a adenoviral dominant-negative Smad3 blocked activin-mediated cell cycle arrest and gene transcription. Activin maintained expression of p21 and p27 cyclin-dependent kinase inhibitors involved in cell cycle control, enhanced expression of p15, reduced cyclin A expression, and reduced phosphorylation of the retinoblastoma (Rb) protein. Smad3 overexpression recapitulated activin-induced p15 expression and repression of cyclin A and Rb phosphorylation. These data indicate that activin A inhibits breast cancer cellular proliferation and activates Smads responsible for initiating cell cycle arrest.

Cloning of Smad2, Smad3, Smad4, and Smad7 from the goldfish pituitary and evidence for their involvement in activin regulation of goldfish FSHbeta promoter activity

Follicle-stimulating hormone (FSH), a glycoprotein consisting of an alpha subunit and a unique beta subunit, is essential for gonadal development and function in vertebrates including teleosts. FSH is regulated by a variety of neuroendocrine and endocrine factors, and its biosynthesis is primarily determined by the expression of the beta subunit. Although the regulation of FSH biosynthesis has been well documented in mammals, the molecular mechanisms underlying the regulation are poorly understood. Our previous studies demonstrated that activin stimulated goldfish FSHbeta expression in the primary pituitary cell culture and enhanced its promoter activity in the mouse gonadotrope cell line LbetaT-2 cells. However, little is known about the signal transduction pathway involved in the transcriptional activation of this gene by activin. To assess the involvement of intracellular signaling protein Smads in regulating goldfish FSHbeta promoter, we first cloned full-length cDNAs for goldfish Smad2, Smad3, Smad4, and Smad7 from the pituitary. All Smads cloned show high sequence conservation with their mammalian counterparts. The spatial expression of these Smads overlapped with that of activin subunits and its receptors in various tissues examined. In addition, we demonstrated that activin induced Smad3 and Smad7 expression, but not Smad2 and Smad4. Co-transfection of Smad2 or Smad3 cDNA into the LbetaT-2 cells with the reporter construct of goldfish FSHbeta promoter significantly enhanced basal and activin-stimulated reporter (SEAP, secreted alkaline phosphatase) expression, while Smad7 completely blocked basal and Smad2/3-stimulated FSHbeta activity. Interestingly, the effect of Smad3 was much higher than that of Smad2, suggesting that Smad3 is likely the principal signal transducing molecule involved in activin stimulation of FSHbeta expression in the goldfish. This work lays a foundation for further analysis of goldfish FSHbeta promoter for the cis-regulatory elements involved in activin signaling.

Production and localization of activins and activin type IIA and IIB receptors by the human endosalpinx

Fallopian tubes from ten premenopausal women were collected and examined for the presence of inhibin, activin and its type IIA and IIB receptors (ActRIIA and ActRIIB) in the endosalpinx. Immunocytochemistry demonstrated clear staining for the betaA, betaB subunits and ActRIIA and ActRIIB that increased in intensity from the isthmus to the ampulla. No staining for the alpha subunit was observed. Whilst the staining of the betaA subunit and ActRIIA was seen in almost every epithelial cell, staining for the betaB subunit and ActRIIB was more variable. In situ hybridization and RT-PCR confirmed the presence of mRNA for the betaA, betaB subunits and ActRIIA and ActRIIB. These results indicated that the epithelium of the uterine tube is able to synthesize activin but not inhibin and has receptors for activin. Activins may thus act as paracrine regulators of tubal epithelial cell function, and embryonic activity may also bind to epithelial receptor and initiate intracellular processes that alter epithelial cell secretions.

[mRNA expression of activin a and follistatin in rabbit mandibular distraction osteogenesis]

OBJECTIVE

To examine the mRNA expression of activin A(ACT A) and follistatin(FS) during mandibular lengthening and to elucidate the regulating pattern of during mandibular distraction osteogenesis.

METHODS

Skeletally mature white New Zealand rabbits were established right mandibular distraction osteogenesis models and the mandibles were lengthened 7 days after osteomy. At the end of latency period and the end of distraction period, 10, 20, 30, 40 and 60 days after fixation, the regenerating tissue of animals' lengthened mandibles and that of the other side normal mandibles were harvested to extract RNA and to analyse ACT A, FS mRNA by RT-PCR.

RESULTS

The expression of ACT A mRNA was not detectable in normal bone tissue and ACT A mRNA began to express at the end of latency period. The expression of ACT A mRNA increased gradually along with the beginning of distraction and reached the peak on the 10th and 20th days of distraction which was 5.04 and 4.98 times as much as that of the end of latency period, respectively. The trend of expression of FS mRNA during mandibular distraction osteogenesis was the same as expression of ACT A mRNA.

CONCLUSION

ACT A/FS play an important role during rabbit mandibular distraction osteogenesis. To examine the mRNA expression of activin A(ACT A) and follistatin(FS) during mandibular lengthening and to elucidate the regulating pattern of during mandibular distraction osteogenesis.

Nodal signaling and vertebrate germ layer formation

The understanding of germ layer formation in vertebrates began with classical experimental embryology. Early in the 20th century, Spemann and Mangold (1924) identified a region of the early embryo capable of inducing an entire embryonic axis. Termed the dorsal organizer, the tissue and the activity have been shown to exist in all vertebrates examined. In mice, for example, the activity resides in a region of the gastrula embryo known as the node. Experiments by the Dutch embryologist Nieuwkoop (1967a, 1967b, 1973, 1977) showed that a signal derived from the vegetal half of the amphibian embryo is responsible for the formation of mesoderm. Nieuwkoop's results allowed the development of in vitro assays that led, in the late 1980s and early 1990s, to the identification of growth factors essential for germ layer formation. Through more recent genetic investigations in mice and zebrafish, we now know that one class of secreted growth factor, called Nodal because of its localized expression in the mouse node, is essential for formation of mesoderm and endoderm and for the morphological rearrangements that occur during gastrulation.

Activin and TR3 orphan receptor: Two 'atheroprotective' genes as evidenced in dedicated mouse models

1. Atherosclerosis is a multifactorial, inflammatory disease of the arterial vessel wall that is promoted by various well-defined risk factors. Although numerous genes, expressed in different vascular and inflammatory cells, have been implicated in this disease, it is widely appreciated that most of the genes and gene products vital for initiation and progression of atherosclerosis are unknown. 2. We follow two strategies in an attempt to make up for the void of essential knowledge. First, we study candidate genes that have not been implied in human atherosclerosis before, notably the differentiation factor activin A. 3. Second, we performed a genome-wide search by differential display reverse transcription-polymerase chain reaction. This study indicated potential involvement of the TR3 orphan receptor transcription factor in smooth muscle cell (SMC) (patho)physiology. 4. To reveal functional involvement of these proteins in SMC during atherosclerosis, we performed experiments with mouse models, adjusted either to the characteristics of a secreted protein or to that of an intracellular transcription factor. 5. The secreted protein activin A was studied in mice infected systemically with recombinant adenoviral vehicles, resulting in predominant hepatic expression and subsequent high protein levels in the circulation. 6. To study the role of TR3 in atherosclerosis, we generated transgenic mice in which promoter sequences were applied that direct expression of the transgenes to SMC of the arterial tree. 7. Two approaches were taken to induce the formation of SMC-rich lesions: (i) activation of femoral artery SMC by placement of a loosely fitting cuff; and (ii) ligation of the carotid artery. 8. The aim of the present review is to illustrate the different approaches that can be taken to assess the potential relevance of genes in atherosclerosis in carefully selected mouse models. 9. Based on the results described, we propose that both activin A and TR3 prevent excessive SMC proliferation.

SEL1L expression in pancreatic adenocarcinoma parallels SMAD4 expression and delays tumor growth in vitro and in vivo

Recent data suggest that SEL1L may play an important role in pancreatic carcinoma, similar to breast cancer, where the expression of SEL1L has been associated with a reduction in both proliferative activity in vitro and clinical tumor aggressiveness. To investigate this possibility, we examined the expression of Sel1L in a series of primary pancreatic carcinomas by immunohistochemistry and characterized the effects of Sel1L overexpression both in vitro and in vivo. In 74 pancreatic cancers analysed, 36% lacked Sel1L expression, although there was no significant correlation between the expression of Sel1L and any clinicopathologic parameter, including survival. However, immunohistochemical reactivity for Sel1L and Dpc4/Smad4 was concordant in 69% of cases (chi(2) test P&<0.004). Overexpression of SEL1L in stably transfected pancreatic cancer cells caused both a decrease in clonogenicity and anchorage-independent growth as well as a significant increase in the levels of activin A and SMAD4. When implanted in nude mice, Suit-2-SEL1L-overexpressing clones displayed a considerably reduced rate of tumor growth. Thus, it can be hypothesized that Sel1L plays an important function in the growth and aggressiveness of pancreatic carcinoma. Moreover, our data provide evidence that SEL1L has an impact on the expression of genes involved in regulation of cellular growth, possibly through the TGF-beta signaling pathway.

Busulfan induces activin A expression in vitro and in vivo: a possible link to venous occlusive disease

PURPOSE

Hepatic venous occlusive disease is a severe side effect after administration of busulfan before hematopoietic stem cell transplantation. The syndrome is characterized by liver enlargement, fluid retention, jaundice, and weight gain. Endothelial injury has been described as the precipitating factor. The link between busulfan administration and endothelial damage has not been established thus far.

METHODS

Complementary deoxyribonucleic acid expression arrays were used to screen for busulfan responsive genes in ECV304 cells. Specific messenger ribonucleic acid and protein levels were examined by real-time polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. Serum samples of 15 pediatric patients with leukemia were analyzed for busulfan and cytokine levels.

RESULTS

We identified a member of the transforming growth factor beta superfamily, activin A, to be induced in the human cell line ECV304 after exposure to busulfan in a time- and concentration-dependent manner. Maximum effects were observed at 120 and 168 hours for activin A messenger ribonucleic acid and protein, respectively. Preincubation with the protein kinase C inhibitor bisindolylmaleimide I (10 nmol/L) abolished activin A induction by busulfan (P <.05). Activin receptors were detected in ECV304. Both tissue factor and cyclooxygenase 2 were significantly induced by busulfan (P <.05). In a parallel in vivo study a significant increase in serum activin A concentration was found 4.5 hours after the second dose of busulfan.

CONCLUSION

The data demonstrate that busulfan induces activin A both in vitro and in vivo. In view of the multiple targets of activin A (inflammation, proliferation, apoptosis, and coagulation), these findings may be of relevance to our understanding of venous occlusive disease.

Increased activin levels in cerebrospinal fluid of rabbits with bacterial meningitis are associated with activation of microglia

Activin, a member of the transforming growth factor superfamily, is upregulated in a number of inflammatory episodes such as septicemia and rheumatoid arthritis. In the CNS, activin has been predominantly assessed in terms of a neuroprotective role. In this report we characterized the activin response in the CNS in a rabbit model of meningitis. In normal animals, cerebrospinal fluid (CSF) activin levels were higher than those in serum, indicating an intracranial secretion of this cytokine. Following intracisternal inoculation with Streptococcus pneumoniae, activin in CSF was unchanged for the first 12 h and then rose progressively; levels were increased approximately 15-fold within 24 h. Activin levels were correlated positively with CSF protein content and with the number of apoptotic neurons in the dentate gyrus. No apparent correlation was observed between CSF activin concentrations and bacterial titer, lactate concentrations or leukocyte density. Using immunohistochemistry, activin staining was localized to epithelial cells of the choroid plexus, cortical neurons and the CA3 region of the hippocampus, with similar staining intensities in both normal and meningitic brains. However, in meningitic brains there was also strong staining in activated microglia and infiltrating macrophages. Taken together, these results demonstrate that activin forms part of the CNS response to immune challenge and may be an important mediator to modulate inflammatory processes in the brain.

Calcium-regulated expression of activin A in RBL-2H3 mast cells

The present study examined the regulatory expression of activin A, a potent growth and differentiation factor, in rat basophilic leukemia (RBL-2H3) mast cells. Treatment of RBL-2H3 cells sensitized with anti-dinitrophenyl IgE with multivalent dinitrophenyl led to a clear increase in RT-PCR products of inhibin/activin beta(A). The steady-state mRNA of inhibin/activin beta(A) was also induced by increasing cytosolic Ca(2+) concentration with ionomycin, which required de novo protein synthesis, and was regulated at the transcriptional level. Pretreatment of RBL-2H3 cells with antagonists or inhibitors for the calmodulin pathway blocked ionomycin-dependent inhibin/activin beta(A) transcription and mRNA induction, suggesting the involvement of calmodulin-dependent kinase (CaMK) and calcineurin. The ionomycin-dependent inhibin/activin beta(A) induction was also partially blocked by preincubation with c-Jun NH(2)-terminal kinase (JNK) and p38 kinase inhibitors, but not with MEK1 inhibitor. These results suggest that inhibin/activin beta(A) gene activation is achieved by the JNK and p38 kinase activation through the calmodulin pathway in mast cells.

Up-regulation of alpha-inhibin expression in the fetal ovary of estrogen-suppressed baboons is associated with impaired fetal ovarian folliculogenesis

We recently demonstrated that the number of primordial follicles was significantly reduced in the ovaries of near-term baboon fetuses deprived of estrogen in utero and restored to normal in animals administered estradiol. Although the baboon fetal ovary expressed estrogen receptors alpha and beta, the mechanism(s) of estrogen action remains to be determined. It is well established that inhibin and activins function as autocrine/paracrine factors that impact adult ovarian function. However, our understanding of the expression of these factors in the primate fetal ovary is incomplete. Therefore, we determined the expression of alpha-inhibin, activin beta(A), activin beta(B), and activin receptors in fetal ovaries obtained at mid and late gestation from untreated baboons and at late gestation from animals in which fetal estrogen levels were reduced by >95% by maternal administration of the aromatase inhibitor CGS 20267 or restored to 30% of normal by treatment with CGS 20267 and estradiol benzoate. Immunocytochemical expression of alpha-inhibin was minimal to nondetectable in fetal ovaries from untreated baboons. In contrast, in baboons depleted of estrogen, alpha-inhibin was abundantly expressed in pregranulosa cells of interfollicular nests and granulosa cells of primordial follicles. Thus, the number (mean +/- SEM) per 0.08 mm2 of fetal ovarian cells expressing alpha-inhibin, determined by image analysis, was similar at mid and late gestation and increased approximately 8-fold (P < 0.01) near term in baboons treated with CGS 20267 and was restored (P < 0.01) to normal in baboons treated with CGS 20267 plus estradiol. Activin beta(A) was detected in oocytes and pregranulosa cells at midgestation and in oocytes and granulosa cells of primordial follicles at late gestation. Activin beta(B) was also expressed in pregranulosa cells and granulosa cells at mid and late gestation, respectively, but was not detected in oocytes. Neither the pattern nor the apparent level of expression of activin beta(A) or beta(B) were altered in fetal ovaries of baboons treated with CGS 20267 or CGS 20267 and estrogen. Activin receptors IA, IB, IIA, and IIB were detected by Western blot analysis in fetal ovaries at mid and late gestation, and expression was not altered by treatment with CGS 20267 or CGS 20267 and estrogen. Activin receptors IB and IIA were localized to oocytes and pregranulosa cells at midgestation and to granulosa cells and oocytes of primordial follicles at late gestation. Thus, the decrease in the number of follicles in the primate fetal ovary of baboons deprived of estrogen in utero was associated with increased expression of alpha-inhibin. Therefore, we propose that estrogen regulates fetal ovarian follicular development by controlling alpha-inhibin expression and, thus, the intraovarian inhibin:activin ratio.

Activin a produced by ureteric bud is a differentiation factor for metanephric mesenchyme

The present study was conducted to investigate the role of the activin-follistatin system in the development of metanephros. Organ culture system and cultured metanephric mesenchymal cells were used to address this issue. Activin A was localized in ureteric bud. Activin type II receptor was localized in ureteric bud as well as metanephric mesenchyme. In an organ culture system, exogenous activin A reduced the size of cultured metanephroi, delayed ureteric bud branching, and enlarged the tips of ureteric bud. Follistatin, an antagonist of activin A was used to clarify the role of endogenous activin A. Exogenous follistatin enlarged the size of cultured metanephroi, increased ureteric bud branching, and promoted cell growth in ureteric bud. Blockade of activin signaling by adenoviral transfection of dominantly negative activin mutant receptor mimics the effect of follistatin. In cultured metanephric mesenchymal cells, activin A promoted cell growth; conversely, follistatin induced apoptosis. Furthermore, activin A induced the expressions of epithelial differentiation markers in these cells. These results suggest that activin A produced by ureteric bud is not only an important regulator of ureteric bud branching, but also a differentiation factor for metanephric mesenchyme during kidney development.

Inhibition of epithelial ductal branching in the prostate by sonic hedgehog is indirectly mediated by stromal cells

Sonic hedgehog (Shh), a vertebrate homologue of the Drosophila segment-polarity gene hedgehog, has been reported to play an important role during normal development of various tissues. Abnormal activities of Shh signaling pathway have been implicated in tumorigenesis such as basal cell carcinomas and medulloblastomas. Here we show that Shh signaling negatively regulates prostatic epithelial ductal morphogenesis. In organotypic cultures of developing rat prostates, Shh inhibited cell proliferation and promoted differentiation of luminal epithelial cells. The expression pattern of Shh and its receptors suggests a paracrine mechanism of action. The Shh receptors Ptc1 (Patched1) and Ptc2 were found to be expressed in prostatic stromal cells adjacent to the epithelium, where Shh itself was produced. This paracrine model was confirmed by co-culturing the developing prostate in the presence of stromal cells transfected with a vector expressing a constitutively active form of Smoothened, the real effector of the Shh signaling pathway. Furthermore, expression of activin A and TGF-beta1 that were shown previously to inhibit prostatic epithelial branching was up-regulated following Shh treatment in the organotypic cultures. Taken together, these results suggest that Shh negatively regulates prostatic ductal branching indirectly by acting on the surrounding stromal cells, at least partly via up-regulating expression of activin A and TGF-beta1.

Decidual activin: its role in the apoptotic process and its regulation by prolactin

Successful pregnancy requires profound differentiation and reorganization of the uterine tissues including, as pregnancy progresses, extensive apoptosis of decidual tissue to accommodate the developing conceptus. We have previously shown a positive correlation between expression of activin A and apoptosis in the decidua and have also shown that expression of activin A occurs at the time when prolactin (PRL) receptors disappear from decidual cells. The goals of this study were to examine whether activin A plays a role in decidual apoptosis and whether expression of activin A in the decidua is regulated by PRL and placental lactogens. Studies were carried out using primary rat decidual cells, a decidual cell line (GG-AD), and PRL null mice. Treatment of decidual cells with activin A significantly increased DNA degradation, caspase 3 activity, and caspase 3 mRNA expression. However, this effect was observed only in the absence of endogenous activin production by these cells. Addition of follistatin to decidual cells that were producing activin A decreased both caspase 3 activity and mRNA expression. Similarly, addition of activin-blocking antibodies to cultures of GG-AD cells, which also produce activin A, caused a reduction in both DNA degradation and caspase 3 activity. PRL and placental lactogens caused an inhibition of activin A mRNA expression in primary decidual cells. Even more convincingly, decidua of PRL null mice expressed abundant activin A at a time when no expression of this hormone is detected in wild-type mice and treatment of PRL null mice with PRL caused a profound inhibition of activin A mRNA expression. In summary, our investigations into the role and regulation of decidual activin have revealed that activin A can induce cell death in the decidua and that its expression is under tight regulation by PRL and placental lactogens.

Regulation of activin A expression in mast cells and asthma: its effect on the proliferation of human airway smooth muscle cells

Activin A, a homodimeric protein (betaAbetaA) and a member of the TGF-beta superfamily, is involved in the inflammatory repair process. Using cDNA microarray analysis, we discovered strong induction of the activin betaA gene in human mast cells (MC) on stimulation with PMA and calcium ionophore (A23187). Activin betaA mRNA was also highly induced in primary cultured murine bone marrow MC (BMMC) after stimulation by IgE receptor cross-linking. Secretion of activin A was evident in human mast cell-1 line cells 3 h after stimulation and progressively increased over time. Activin A was present in the cytoplasm of activated but not unstimulated murine bone marrow MC as demonstrated by immunofluorescence studies, suggesting that secretion of activin A by MC was due to de novo synthesis rather than secretion of preformed protein. Activin A also colocalized with human lung MC from patients with asthma by double-immunofluorescence staining. Furthermore, secretion of activin A was significantly increased in the airway of wild-type mice after OVA sensitization followed by intranasal challenge. Secretion of activin A, however, was greatly reduced in MC-deficient WBB6F(1)-W/W(v) mice as compared with wild-type mice, indicating that MC are an important contributor of activin A in the airways of a murine asthma model. Additionally, activin A promoted the proliferation of human airway smooth muscle cells. Taken together, these data suggest that MC-derived activin A may play an important role in the process of airway remodeling by promoting the proliferation of airway smooth muscle.

Ovarian follicle development in the laying hen is accompanied by divergent changes in inhibin A, inhibin B, activin A and follistatin production in granulosa and theca layers

To study the potential involvement of inhibin A (inhA), inhibin B (inhB), activin A (actA) and follistatin (FS) in the recruitment of follicles into the preovulatory hierarchy, growing follicles (ranging from 1 mm to the largest designated F1) and the three most recent postovulatory follicles (POFs) were recovered from laying hens (n=11). With the exception of <4 mm follicles and POFs, follicle walls were dissected into separate granulosa (G) and theca (T) layers before extraction. Contents of inhA, inhB, actA and FS in tissue extracts were assayed using specific two-site ELISAs and results are expressed per mg DNA. InhB content of both G and T followed a similar developmental pattern, although the content was >4-fold higher in G than in T at all stages. InhB content was very low in follicles <4 mm but increased ~50-fold (P<0.0001) to peak in 7-9 mm follicles, before falling steadily as follicles entered and moved up the follicular hierarchy (40-fold; 8 mm vs F2). In stark contrast, inhA remained very low in prehierarchical follicles (< or =9 mm) but then increased progressively as follicles moved up the preovulatory hierarchy to peak in F1 (approximately 100-fold increase; P<0.0001); In F1 >97% of inhA was confined to the G layer whereas in 5-9 mm follicles inhA was only detected in the T layer. Both inhA and inhB contents of POFs were significantly reduced compared with F1. Follicular actA was mainly confined to the T layer although detectable levels were present in G from 9 mm; actA was low between 1 and 9 mm but increased sharply as follicles entered the preovulatory hierarchy (approximately 6-fold higher in F4; P<0.0001); levels then fell approximately 2-fold as the follicle progressed to F1. Like actA, FS predominated in the T although significant amounts were also present in the G of prehierarchical follicles (4-9 mm), in contrast to actA, which was absent from the G. The FS content of T rose approximately 3-fold from 6 mm to a plateau which was sustained until F1. In contrast, the FS content of G was greatest in prehierarchical follicles and fell approximately 4-fold in F4-F1 follicles. ActA and FS contents of POFs were reduced compared with F1. In vitro studies on follicle wall explants confirmed the striking divergence in the secretion of inhA and inhB during follicle development. These findings of marked stage-dependent differences in the expression of inhA, inhB, actA and FS proteins imply a significant functional role for these peptides in the recruitment and ordered progression of follicles within the avian ovary.

Dynamics and localization of activin A expression in rat gastric ulcers

BACKGROUND

Activin A, the homodimer of the activin/inhibin betaA subunit, has been shown to participate in cutaneous wound healing. In this study we intended to determine its part in gastric ulceration.

METHODS

Activin A expression was studied by immunohistochemistry and in situ hybridization in acetic-acid-induced chronic gastric ulcers in rat. The dynamics of this process were also assessed by quantitative real time RT-PCR and RNase protection assays (RPA). The effects of different doses of this cytokine on epithelial and mesenchymal cell proliferation were quantitated in vitro.

RESULTS

Low amounts of activin A and its mRNA were expressed by epithelia, endothelia and fibroblasts in intact gastric tissue. Granulation tissue of gastric ulcers and gastric glands adjacent to the ulcer rim expressed markedly increased amounts of activin protein as well as activin/inhibin betaA mRNA. RPA and RT-PCR studies revealed a more than 3-fold increase in the relative abundance of this mRNA. Activin A did not affect the proliferation rate of fibroblasts and epithelial cells in vitro.

CONCLUSIONS

Activin A participates in gastric ulcer healing in a similar fashion as in cutaneous wounding. Its expression on protein and mRNA level is markedly increased in ulcer base and rim.

Effect of hypoxia on placental activin A, inhibin A and follistatin synthesis

Placental activin A and inhibin A output is increased in pre-eclampsia, a condition characterized by placental hypoxaemia, whereas follistatin secretion is unaltered. We investigated whether hypoxia was the basis for elevated placental activin A and inhibin A output. First trimester and term placental explants were grown in 5-6% dissolved O(2) (n=10/trimester) and 200 microM cobalt chloride (CoCl(2),n =6/trimester) to simulate environmental and cellular hypoxia respectively, for up to 72 h. Activin A, inhibin A and follistatin production were compared with control cultures grown in standard media at 20% O(2). In first trimester and term placenta, activin A output declined significantly under 5-6% O(2) (P=0.006 and 0.001 after 48 h respectively). Inhibin A declined significantly under 5-6% O(2), mainly in first trimester placenta (P=0.03, 24h). CoCl(2) significantly elevated activin A production in term placenta (P=0.003, 48 h), whereas inhibin A output was unaffected. Neither low O(2) or CoCl(2) altered follistatin output from first trimester or term placenta. These findings suggest that there may be novel O(2) sensing mechanism/s that down regulate activin A and inhibin A in the placenta and that low O(2) is not the mechanism behind increased placental inhibin A or activin A output in pre-eclampsia.

Hypoxia inhibits activin A production by term villous trophoblast in vitro

Elevated activin A and inhibin A levels have been associated with pre-eclampsia, a pregnancy-related disorder associated with placental hypoxaemia. We investigated the effect of in vitro hypoxia on the production of inhibin A, activin A and its binding protein follistatin in term villous placental explants (n=4-7) and trophoblast monolayer cultures (n=4). Explants and trophoblasts were incubated for 24-72 h under either normoxic (21 per cent O(2)) or hypoxic (2 per cent O(2)) conditions. Production of activin A, inhibin A, and follistatin was determined by specific ELISA. After 48 h of hypoxia, villous explants exhibited a significant reduction in activin A production rates to 53.2 +/- 8.9 per cent (mean +/- SEM, P<0.05) of normoxic controls which was sustained after 72 h in culture (46.8 +/- 5.9 per cent), whereas production by trophoblast monolayers was not affected by hypoxia. Follistatin production was decreased to 53.7 +/- 9.2 per cent of control (P<0.05) after 48 h of hypoxia. Inhibin A production remained unaltered in both culture systems. Our data demonstrate for the first time that hypoxia lowers term placental activin A and follistatin production in vitro. These findings do not support the notion that elevated circulating activin A levels in pre-eclampsia originate from the placenta as a result of placental hypoxia. Other as yet unknown maternal/placental factors may contribute to elevated activin A production in women with severe pre-eclampsia.

Production of activins by the human endosalpinx

Uterine tubes from 11 premenopausal and 6 postmenopausal women were collected and examined for the presence of inhibin, activin, and follistatin in the endosalpinx. Immunocytochemistry of tissue from both the isthmic and ampullary regions demonstrated clear staining for the beta(A)- and beta(B)-subunits that increased in intensity from the isthmus to the ampulla. Staining for follistatin showed a similar pattern, but no staining for the alpha-subunit was observed. Although staining for the beta(A)-subunit was seen in almost every epithelial cell, staining for the beta(B)-subunit was more variable. Western blotting showed a band with an apparent molecular mass of 28 kDa (corresponding to the activin dimer) and a band of approximately 60 kDa (corresponding to the pro-protein of activin). In situ hybridization confirmed the presence of mRNA for the beta(A)- and beta(B)-subunits in the endosalpinx. These results indicate that the endosalpinx is able to synthesize activin, not inhibin, suggesting that in premenopausal women they may have an important role in the biology of the developing embryo. The role in postmenopausal women is less certain, but could lead to the stimulation of FSH secretion by the pituitary gland or other autocrine/paracrine function within the uterine tube.