βA Gene Research Articles

Localization and regulatory function of Yin Yang 1 (YY1) in chicken testis.

In mammals, Yin Yang 1 (YY1), a pervasively expressed transcription factor related to many biological processes as an activator or inhibitor of the transcription of various genes, plays a critical role in the development of male gonads and spermatogenesis. Although the role of YY1 on the development of male gonads and spermatogenesis in mammals has been reported, its function on chicken testis are yet to be clarified. In this study, we used immunofluorescence analysis to investigate the location of YY1 in chicken testis. In embryo testis, YY1 was detected in spermatogonia and Sertoli cells, while in adult testis, YY1 was shown to be expressed in spermatogenic cells and Sertoli cells, but not in spermatozoa. Furthermore, we investigated the regulatory functions of YY1 in chicken testicular Sertoli cells by combining overexpression with RNA-sequencing. Overexpression of YY1 in Sertoli cells revealed a total of 2955 differentially expressed genes involved in various biological processes, such as male gonad development and seminiferous tubule development. Overexpression of YY1 also caused significant differences in the expression of the androgen receptor gene and the inhibin βA gene, two major genes involved in the regulation of spermatogonia in Sertoli cells. These observations indicate that YY1 may regulate the development and function of the gonads by affecting the secretion of cytokines and hormones in Sertoli cells to mediate the production and differentiation of spermatogonia.

Gilz-Activin A as a Novel Signaling Axis Orchestrating Mesenchymal Stem Cell and Th17 Cell Interplay.

Mesenchymal stem cells (MSC) are highly immunosuppressive cells able to reduce chronic inflammation through the active release of mediators. Recently, we showed that glucocorticoid-induced leucine zipper (Gilz) expression by MSC is involved in their therapeutic effect by promoting the generation of regulatory T cells. However, the mechanisms underlying this pivotal role of Gilz remain elusive.Methods and Results In this study, we have uncovered evidence that Gilz modulates the phenotype and function of Th1 and Th17 cells likely by upregulating the level of Activin A and NO2 secreted by MSC. Adoptive transfer experiments sustained this Gilz-dependent suppressive effect of MSC on Th1 and Th17 cell functions. In immunoregulatory MSC, obtained by priming with IFN-γ and TNF-α, Gilz was translocated to the nucleus and bound to the promoters of inos and Activin βA to induce their expression. The increased expression of Activin A directly impacted on Th17 cells fate by repressing their differentiation program through the activation of Smad3/2 and enhancing IL-10 production.Conclusion Our results reveal how Gilz controls inos and Activin βA gene expression to ultimately assign immunoregulatory status to MSC able to repress the pathogenic Th17 cell differentiation program and uncover Activin A as a novel mediator of MSC in this process.

A Highly Sensitive Assessment Tool for the Gene Editing Efficiency of Sickle Cell Disease Hemoglobin Beta Gene

In sickle cell disease, a single point mutation in hemoglobin β gene (HBB) results in the substitution of valine for glutamic acid at position 6 of the β globin protein sequence, causing the deformation of red blood cells into a sickle (or crescent) shape. With the development of powerful gene editing tools, scientists are initiating the correction of the point mutation of HBB gene in CD34+ hematopoietic stem cells and induced pluripotent stem cells. Although the results are very exciting, the evaluation method of the gene editing is primitive. Currently, the modification at the mutation site is identified and quantified using Restriction Fragment Length Polymorphism (RFLP), which involves PCR amplification, restriction enzyme digestion and gel electrophoresis. The accuracy of the gene editing efficiency depends heavily on the quantification of the DNA bands in the gel images, which is inherently imprecise. We have developed a novel technique to quantify the correction efficiency of HBB gene editing using a fluorescence tagging of the edited DNA sequence. This method provides excellent sensitivity and accuracy, and saves time and labor, eliminating a process of gel electrophoresis. We demonstrate the assessment of gene editing in HBB of K562 cells, in which the wild type HBB (βA gene) is converted to mutant βs using the gene editing tools (i.e. Transcription Activator-Like Effector Nucleases (TALENs) and single-stranded oligo deoxynucleotides (ssODNs)). We present limited information here due to the sensitivity of the intellectual property, but will discuss in detail the experimental procedures and data at the American Society of Hematology meeting. DisclosuresNo relevant conflicts of interest to declare.

First Description of a β-Thalassemia Mutation, −86 (C > G) (HBB: c.−136C > G), in a Chinese Family

We present the first description of a Chinese family with a β-thalassemia (β-thal) mutation −86 (C > G) (HBB: c.−136C > G). This mutation changes the conserved promoter sequence within the proximal CACCC box of the β-globin gene that leads to a phenotype of β+-thal. The β-globin haplotype analysis revealed that the −86 mutation in our case was linked with haplotype I [+ − − − − + +]. This haplotype was commonly found both in the β-thal mutation and the βA gene. Our results suggest that the −86 mutation possibly does not have a distinct origin.

Polymorphism of the inhibin βA gene and its relationship with superovulation traits in Chinese Holstein cows

Inhibin is a major regulator of secretion of follicle-stimulating hormone, which is involved in follicular development and regulation of steroidogenesis in females. The objectives of this study were to detect polymorphisms of the bovine inhibin beta-A subunit (INHβA) gene and to evaluate its associations with superovulatory responses in 171 Chinese Holstein cows treated for superovulation. Polymerase chain reaction-restricted fragment length polymorphism revealed a C>T transition determining the StyI polymorphism at position 7639 in intron I of the bovine INHβA gene, and three genotypes (CC, CT, and TT) were detected. The frequencies of the three genotypes showed a tendency for CT > TT > CC, and this polymorphism was in Hardy-Weinberg equilibrium. Statistical analysis revealed no significant differences of least square means for superovulation traits among the three genotypes (P > 0.05). These results demonstrate, for the first time, that the detected loci of the INHβA gene have no significant effects on superovulation performance in Chinese Holstein cows.

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.

Expression of thyroid hormone receptor βA gene assayed by transgenic Xenopus laevis carrying its promoter sequences

The responsiveness of thyroid hormone responsive element (TRE)-containing promoter sequence to thyroid hormone (TH) was studied utilizing Xenopus laevis carrying a transgene containing 5′-upstream region of TRβA1 gene and green fluorescent protein (EGFP) gene. EGFP-expression was seen first in neurulae, which continued to stage 45, then became weak, and again started to increase at the prometamorphic stage, culminating at the metamorphic climax stage. Immunohistochemistry identified eyes, viscera, and muscles as the EGFP-expressing larval tissues. The treatment of premetamorphic tadpoles with TH induced the precocious EGFP-expression. We also showed that the transgenic Xenopus adults were responsive to exogenous TH, a high responsiveness being seen in brain, small intestine, kidney, and bone. TRβ-expression in the embryo, larva, and adult was verified by Western blotting. Thus, TH not only regulates the metamorphosis, but also might play some biological role(s) in embryos and adults.

Evidence for local production of inhibin A and activin A in patients with ovarian endometriosis

Objective: To evaluate the expression of inhibin A and activin A in ovarian endometriosis. Design: Uncontrolled cross-sectional study and controlled prospective in vitro study. Setting: Academic health centers in Siena, Udine, Sassari, and Milan, Italy. Patient(s): A group of women ( n = 19) who underwent laparoscopic excision of ovarian endometriotic cysts. Intervention(s): Specimens of serum, peritoneal fluid, and cystic fluid, ovarian tissue for immunohistochemistry, and endometriotic cells for primary culture were collected. Cell cultures were also prepared from proliferative endometrium of women without endometriosis. Main Outcome Measures(s): Dimeric inhibin A and activin A concentrations in biological fluids; immunostaining of α and βA subunits in ovarian endometrioma; α and βA gene expression in cultured endometriotic cells compared with normal endometrium. Result(s): Inhibin A and activin A concentrations in the cystic fluid were slightly higher than in peritoneal fluid and significantly higher than in serum ( P<.05). Immunoreactive α and βA subunits were strongly expressed both in the epithelial and stromal components of ovarian endometrioma. The relative abundance of βA mRNA was significantly decreased in endometriotic cells compared with eutopic stromal cells. Conclusion(s): The results of the present study provide evidence for a local production and secretion of inhibin A and activin A in ovarian endometriotic cysts.

Activin A stimulates type IV collagenase (matrix metalloproteinase-2) production in mouse peritoneal macrophages.

The role of activin, a dimer of inhibin beta subunit, in mouse peritoneal macrophages was evaluated. Activin activity in the cultured macrophages was augmented in response to activation by LPS. In Western blot analysis, immunoreactive activin A was detected in the culture medium only when the macrophages were stimulated by LPS. Although mRNA expression of betaA subunit was detected, that of alpha and betaB subunit was not found in macrophages by reverse RT-PCR. The activin betaA mRNA level was increased in macrophages by LPS, suggesting that the activin production augmented by LPS is regulated at the mRNA level of the betaA gene. The mRNAs of four activin receptors (ActRI, ActRIB, ActRII, and ActRIIB) were also detected in the peritoneal macrophages, and the mRNA levels, except for ActRIB, were decreased during the LPS treatment. Exogenous activin A stimulated the mRNA expression and gelatinolytic activity of matrix metalloproteinase-2 (MMP-2) in macrophages in both the presence and the absence of LPS. In contrast, activin did not affect the production of MMP-9 in macrophages. These results suggested that 1) mouse peritoneal macrophages produced activin A; 2) expression of activin A was enhanced with activation of the macrophages; 3) the macrophages also expressed activin receptors; and 4) exogenous activin A stimulated MMP-2 expression and activity, implicating activin A as an positive regulator of MMP-2 expression. Considering that MMP-2 constitutes the rate-limiting proteinase governing the degradation of basement membrane collagens, activin A may be involved in migration and infiltration of macrophages through the basement membrane in an inflammatory state.

Activin A Promotes Progenitor Differentiation into Photoreceptors in Rodent Retina

Activins are TGF β-like proteins that were first discovered for their actions on the reproductive system, but have subsequently been shown to play a role in a variety of developmental processes. Previous studies have demonstrated that activins and their receptors are present in the developing retina, as well as other regions of the embryonic nervous system. We used both in vitro and in vivo approaches to test for functions of activin during retinal development. We found that activin A treatment of embryonic day 18 rat retinal cultures causes the progenitor cells in the cultures to exit the cell cycle and differentiate into rod photoreceptors. This effect is dose-dependent and the promotion of rod photoreceptor differentiation is specific, since the other primary retinal neurons generated in these cultures, the C1+ amacrine cells, are not affected by activin A treatment. Mice with homozygous deletion of the activin βA gene show a specific decrease in the number of rod photoreceptors compared to wild-type or heterozygous littermates. These data demonstrate that activin A is an important regulator of photoreceptor differentiation in the developing retina.

Male Sterility in Transgenic Mice Expressing Activin βA Subunit Gene in Testis

Activins and inhibins, which are endocrine regulators of anterior pituitary function, have also been reported to participate in the paracrine and autocrine regulation of reproductive function. To determine the in vivo effects of overexpressed activin/inhibin, we generated transgenic mice carrying the human activin/inhibin βA subunit mini gene under the regulatory control of the mouse methallothionein promoter. In one of the transgenic line analyzed, the βA subunit gene was preferentially expressed in the testis. Ectopic and allochronic expression of the βA gene started at 3 weeks after birth and transgenic male mice became sterile in the ensuing several weeks. Histological analysis revealed testicular degeneration in these mice. The results from this transgenic line strongly support the in vivo activity of activin/inhibin in male reproductive functions.

Control of digit formation by activin signalling.

Major advances in the genetics of vertebrate limb development have been obtained in recent years. However, the nature of the signals which trigger differentiation of the mesoderm to form the limb skeleton remains elusive. Previously, we have obtained evidence for a role of TGFbeta2 in digit formation. Here, we show that activins A and B and/or AB are also signals involved in digit skeletogenesis. activin betaA gene expression correlates with the initiation of digit chondrogenesis while activin betaB is expressed coincidently with the formation of the last phalanx of each digit. Exogenous administration of activins A, B or AB into the interdigital regions induces the formation of extra digits. follistatin, a natural antagonist of activins, is expressed, under the control of activin, peripherally to the digit chondrogenic aggregates marking the prospective tendinous blastemas. Exogenous application of follistatin blocks physiological and activin-induced digit formation. Evidence for a close interaction between activins and other signalling molecules, such as BMPs and FGFs, operating at the distal tip of the limb at these stages is also provided. Chondrogenesis by activins is mediated by BMPs through the regulation of the BMP receptor bmpR-1b and in turn activin expression is upregulated by BMP signalling. In addition, AER hyperactivity secondary to Wnt3A misexpression or local administration of FGFs, inhibits activin expression. In correlation with the restricted expression of activins in the course of digit formation, neither activin nor follistatin treatment affects the development of the skeletal components of the stylopod or zeugopod indicating that the formation of the limb skeleton is regulated by segment-specific chondrogenic signals.

Transcription from the Thyroid Hormone-dependent Promoter of the Xenopus laevis Thyroid Hormone Receptor βA Gene Requires a Novel Upstream Element and the Initiator, but Not a TATA Box

The thyroid hormone receptor (TR) beta genes in Xenopus laevis are regulated by thyroid hormone in all organs of an animal during metamorphosis. This autoregulation appears to be critical for systematic transformations of different organs as a tadpole is transformed into a frog. To understand this autoregulation, we have previously identified a thyroid hormone response element in the hormone-dependent promoter of the X. laevis TRbetaA gene. We report here the detailed characterization of the promoter. We have now mapped the transcription start site and demonstrated the existence of an initiator element at the start site critical for promoter function. More important, our deletion and mutational experiments revealed a novel upstream DNA element that is located 125 base pairs upstream of the start site and that is essential for active transcription from the promoter. Promoter reconstitution experiments showed that this novel element does not function as an enhancer, but acts as a core promoter element, which, together with the initiator, directs accurate transcription from the promoter. Finally, we provide evidence for the existence of a protein(s) that specifically recognizes this element. Our studies thus demonstrate that the TRbetaA promoter has a unique organization consisting of an initiator and a novel upstream promoter element. Such an organization may be important for the ubiquitous but tissue-dependent temporal regulation of the gene by thyroid hormone during amphibian metamorphosis.

The Sickle Gene Polymorphism in North Africa

AbstractAnalysis of the restriction endonuclease Hpa 1–β globin gene linkage has been performed in a predominantly Arab population of North Africa possessing the sickle (βS)gene. In normal controls, the β globin (βA) gene is found associated with a 7.6 kilobase (kb) or 7.0 kb Hpa 1 fragment (54/54 assignable βA genes), whereas the βs gene is found associated with a 13 kb Hpa 1 fragment (42/42 assignable βS genes). The results demonstrate a very tight linkage of the βS gene to the 13 kb Hpa 1 fragment as well as a very low probability that a βA gene will be found on a 13 kb Hpa 1 fragment. Thus, the North African population presents a nearly ideal opportunity for prenatal diagnosis solely by Hpa 1–β globin gene linkage analysis. Additionally, the evidence supports the hypothesis that the βS gene flowed from West Africa rather than from Arab populations in the Middle East.

DISTINGUISHING SICKLE TRAIT FROM SICKLE-β-THALASSEMIA IN THE ABORTED FETUS

Continuing studies of hemoglobin synthesis by reticulocytes of abortuses have provided further information necessary for prenatal diagnosis of sickle cell anemia and β-thalassemia. These data indicate that sickle trait and sickle-β-thalassemia can be distinguished in the fetus. Moreover, since the AS fetus with one βA gene makes 50% as much Hb A as the normal fetus with two βA genes, the percent of Hb A synthesis in fetuses with β-thalassemia trait who have one normal βA gene should be similar to that observed in the AS fetus (4.6) and, therefore, different from that of the normal fetus (9.3). Thus, in all probability β-thalassemia trait can be distinguished from normal during fetal life.