MicroRNAs regulate pituitary development, and microRNA 26b specifically targets lymphoid enhancer factor 1 (Lef-1), which modulates pituitary transcription factor 1 (Pit-1) expression

Approaches based on natural products and miRNAs in pituitary adenomas: unveiling therapeutic intervention

Pituitary adenomas (PAs) are tumors originating in the pituitary gland, a small gland located at the base of the brain. They are the most common type of pituitary tumor, affecting approximately 1 in 10 people over their lifetime. Common symptoms include headaches, vision problems, hormonal imbalances, and weight changes. Treatment options depend on the type and size of the adenoma and may consist of medication, surgery, radiation therapy, or a combination. PAs are typically benign and slow-growing, but they can cause significant health issues if left untreated. Proper diagnosis and management by an experienced multidisciplinary team is important for achieving the best outcomes. Natural compounds like celastrol, curcumin, quercetin, apigenin, resveratrol, epigallocatechin gallate (EGCG), and genistein have shown the ability to inhibit cell growth, promote cell death, and suppress hormone activity in pituitary tumor cells, suggesting their potential as alternative or complementary treatments for PAs. MicroRNAs (miRNAs) are a kind of tiny RNA molecules that do not code for proteins and have a vital function in controlling gene expression. These 21-23 nucleotide-long molecules regulate gene expression by binding to complementary sequences in mRNA molecules, leading to mRNA degradation. miRNAs participate in a wide range of biological activities, including apoptosis, metastasis, differentiation, and proliferation. The research indicates that miRNAs play a crucial role in the pathogenesis, therapeutic approaches, diagnosis, and prognosis of PAs. This review article will provide a comprehensive analysis of the current understanding of the efficacy of naturally derived anti-cancer agents in the treatment of PAs. Furthermore, the study provides a comprehensive assessment of the miRNAs in PAs, their role in the development of PAs, and their potential application in the treatment of the condition.

Micromanaging the neuroendocrine system - A review on miR-7 and the other physiologically relevant miRNAs in the hypothalamic-pituitary axis

The hypothalamic-pituitary axis is central to the functioning of the neuroendocrine system and essential for regulating physiological and behavioral homeostasis and coordinating fundamental body functions. The expanding line of evidence shows the indispensable role of the microRNA pathway in regulating the gene expression profile in the developing and adult hypothalamus and pituitary gland. Experiments provoking a depletion of miRNA maturation in the context of the hypothalamic-pituitary axis brought into focus a prominent involvement of miRNAs in neuroendocrine functions. There are also a few individual miRNAs and miRNA families that have been studied in depth revealing their crucial role in mediating the regulation of fundamental processes such as temporal precision of puberty timing, hormone production, fertility and reproduction capacity, and energy balance. Among these miRNAs, miR-7 was shown to be hypothalamus-enriched and the top one highly expressed in the pituitary gland, where it has a profound impact on gene expression regulation. Here, we review miRNA profiles, knockout phenotypes, and miRNA interaction (targets) in the hypothalamic-pituitary axis that advance our understanding of the roles of miRNAs in mammalian neurosecretion and related physiology.

RNA Technology to Regenerate and Repair Alveolar Bone Defects

microRNA-200a (miR-200a) targets multiple signaling pathways that are involved in osteogenic differentiation and bone development. However, its therapeutic function in osteogenesis and bone regeneration remains unknown. In this study, we use in vitro and in vivo models to investigate the molecular function of miR-200a overexpression and miR-200a inhibition using a plasmid-based miR inhibitor system (PMIS) on osteogenic differentiation and bone regeneration. Inhibition of miR-200a using PMIS-miR-200a significantly increased osteogenic biomarkers of human embryonic palatal mesenchyme cells and promoted bone regeneration in rat tooth socket defects. In rat maxillary M1 molar extractions, the supporting tooth structures were removed with an implant drill to yield a 3-mm defect in the alveolar bone. A collagen sponge was inserted into the open alveolar defect and PMIS-miR-200a plasmid DNA was added to the sponge and the wound sutured to protect the sponge and close the defect. It was important to remove the existing tooth supporting structure, which can influence alveolar bone regeneration. The alveolar bone was regenerated in 4 wk. The collagen sponge acts to stabilize and deliver the PMIS-miR-200a DNA to cells entering the sponge in the bone defect. We show that mesenchymal stem cells expressing CD90 and Stro-1 enter the sponges, take up the DNA, and express PMIS-miR-200a. PMIS-miR-200a initiates a bone regeneration program in transformed cells in vivo. In vitro inhibition of miR-200a was found to upregulate Wnt and BMP signaling activity as well as Runx2, OCN, Lef-1, Msx2, and Dlx5 associated with osteogenesis. Liver and blood toxicity testing of PMIS-miR-200a-treated rats showed no increase in several biomarkers of liver disease. These results demonstrate the therapeutic function of PMIS-miR-200a for rapid bone regeneration. Furthermore, the studies were designed to demonstrate the ease of use of PMIS-miR-200a in solution and applied using a syringe in the clinic through a simple one-time application.

Germline Variants in Sporadic Pituitary Adenomas

Context

Data on germline genetics of pituitary adenomas (PAs) using whole-exome sequencing (WES) are limited.

Objective

This study investigated the germline genetic variants in patients with PAs using WES.

Methods

We studied 134 consecutive functioning (80.6%) and nonfunctioning (19.4%) PAs in 61 female (45.5%) and 73 male patients (54.5%). Their median age was 34 years (range, 11-85 years) and 31 patients had microadenomas (23.0%) and 103 macroadenomas (77%). None of these patients had family history of PA or a known PA-associated syndrome. Peripheral blood DNA was isolated and whole-exome sequenced. We used American College of Medical Genetics and Genomics (ACMG) criteria and a number of in silico analysis tools to characterize genetic variant pathogenicity levels and focused on previously reported PA-associated genes.

Results

We identified 35 variants of unknown significance (VUS) in 17 PA-associated genes occurring in 40 patients (29.8%). Although designated VUS by the strict ACGM criteria, they are predicted to be pathogenic by in silico analyses and their extremely low frequencies in 1000 genome, gnomAD, and the Saudi Genome Project databases. Further analysis of these variants by the Alpha Missense analysis tool yielded 8 likely pathogenic variants in 9 patients in the following genes: AIP:c.767C>T (p.S256F), CDH23:c.906G>C (p.E302D), CDH23:c.1096G>A (p.A366T), DICER1:c.620C>T (p.A207V), MLH1:c.955G>A (p.E319K), MSH2:c.148G>A (p.A50T), SDHA:c.869T>C (p.L290P) and USP48 (2 patients): c.2233G>A (p.V745M).

Conclusion

This study suggests that about 6.7% of patients with apparently sporadic PAs carry likely pathogenic variants in PA-associated genes. These findings need further studies to confirm them.

Non-coding RNAs and exosomal non-coding RNAs in pituitary adenoma

Pituitary adenoma (PA) is the third most common primary intracranial tumor in terms of overall disease incidence. Although they are benign tumors, they can have a variety of clinical symptoms, but are mostly asymptomatic, which often leads to diagnosis at an advanced stage when surgical intervention is ineffective. Earlier identification of PA could reduce morbidity and allow better clinical management of the affected patients. Non-coding RNAs (ncRNAs) do not generally code for proteins, but can modulate biological processes at the post-transcriptional level through a variety of molecular mechanisms. An increased number of ncRNA expression profiles have been found in PAs. Therefore, understanding the expression patterns of different ncRNAs could be a promising method for developing non-invasive biomarkers. This review summarizes the expression patterns of dysregulated ncRNAs (microRNAs, long non-coding RNAs, and circular RNAs) involved in PA, which could one day serve as innovative biomarkers or therapeutic targets for the treatment of this neoplasia. We also discuss the potential molecular pathways by which the dysregulated ncRNAs could cause PA and affect its progression.

DICER1 syndrome and embryonal rhabdomyosarcoma of the cervix: a case report and literature review

Background

Embryonal rhabdomyosarcomas (ERMS) of the uterine cervix and corpus are rare pediatric tumors usually associated with a late age of onset and frequent somatic DICER1 mutation. It may also develop in the context of a familial predisposition such as DICER1 syndrome requiring specific medical care for children and young adults at risk for a broad range of tumors.

Case presentation

This is a case of a prepubescent 9-year-old girl who was presented to our department for metrorrhagias due to a vaginal cervical mass, initially classified as a müllerian endocervical polyp on negative myogenin immunostaining. The patient subsequently manifested growth retardation (-2DS) and learning disabilities leading to genetic explorations and the identification of a germline pathogenic DICER1 variant. The family history revealed thyroid diseases in the father, aunt and paternal grandmother before the age of 20.

Conclusion

Rare tumors such as cervical ERMS associated with a family history of thyroid disease during infancy could be related to DICER1 syndrome. Identifying at-risk relatives is challenging but necessary to detect early DICER1 spectrum tumors in young patients.

The Spectrum of Familial Pituitary Neuroendocrine Tumors

Hereditary pituitary tumorigenesis is seen in a relatively small proportion (around 5%) of patients with pituitary neuroendocrine tumors (PitNETs). The aim of the current review is to describe the main clinical and molecular features of such pituitary tumors associated with hereditary or familial characteristics, many of which have now been genetically identified. The genetic patterns of inheritance are classified into isolated familial PitNETs and the syndromic tumors. In general, the established genetic causes of familial tumorigenesis tend to present at a younger age, often pursue a more aggressive course, and are more frequently associated with growth hormone hypersecretion compared to sporadic tumors. The mostly studied molecular pathways implicated are the protein kinase A and phosphatidyl-inositol pathways, which are in the main related to mutations in the syndromes of familial isolated pituitary adenoma (FIPA), Carney complex syndrome, and X-linked acrogigantism. Another well-documented mechanism consists of the regulation of p27 or p21 proteins, with further acceleration of the pituitary cell cycle through the check points G1/S and M/G1, mostly documented in multiple endocrine neoplasia type 4. In conclusion, PitNETs may occur in relation to well-established familial germline mutations which may determine the clinical phenotype and the response to treatment, and may require family screening.

Identification of Potential miRNA-mRNA Regulatory Network Associated with Pig Growth Performance in the Pituitaries of Bama Minipigs and Landrace Pigs

Pig growth performance is one of the criteria for judging pork production and is influenced by genotype and external environmental factors such as feeding conditions. The growth performance of miniature pigs, such as Bama minipigs, differs considerably from that of the larger body size pigs, such as Landrace pigs, and can be regarded as good models in pig growth studies. In this research, we identified differentially expressed genes in the pituitary gland of Bama minipigs and Landrace pigs. Through the pathway enrichment analysis, we screened the growth-related pathways and the genes enriched in the pathways and established the protein-protein interaction network. The RNAHybrid algorithm was used to predict the interaction between differentially expressed microRNAs and differentially expressed mRNAs. Four regulatory pathways (Y-82-ULK1/CDKN1A, miR-4334-5p-STAT3/PIK3R1/RPS6KA3/CAB39L, miR-4331-SCR/BCL2L1, and miR-133a-3p-BCL2L1) were identified via quantitative real-time PCR to detect the expression and correlation of candidate miRNAs and mRNAs. In conclusion, we revealed potential miRNA-mRNA regulatory networks associated with pig growth performance in the pituitary glands of Bama minipigs and Landrace pigs, which may help to elucidate the underlying molecular mechanisms of growth differences in pigs of different body sizes.

Rno_circ_0001004 Acts as a miR-709 Molecular Sponge to Regulate the Growth Hormone Synthesis and Cell Proliferation

(1) Background: As a novel type of non-coding RNA with a stable closed-loop structure, circular RNA (circRNA) can interact with microRNA (miRNA) and influence the expression of miRNA target genes. However, circRNA involved in pituitary growth hormone (GH) regulation is poorly understood. Our previous study revealed protein kinase C alpha (PRKCA) as the target gene of miR-709. Currently, the expression and function of rno_circRNA_0001004 in the rat pituitary gland is not clarified; (2) Methods: In this study, both bioinformatics analysis and dual-luciferase report assays showed a target relationship between rno_circRNA_0001004 and miR-709. Furthermore, the rno_circRNA_0001004 overexpression vector and si-circ_0001004 were constructed and transfected into GH₃ cells; (3) Results: We found that rno_circRNA_0001004 expression was positively correlated with the PRKCA gene and GH expression levels, while it was negatively correlated with miR-709. In addition, overexpression of rno-circ_0001004 also promoted proliferation and relieved the inhibition of miR-709 in GH₃ cells; (4) Conclusions: Our findings show that rno_circ_0001004 acts as a novel sponge for miR-709 to regulate GH synthesis and cell proliferation, and are the first case of discovery of the regulatory role of circRNA_0001004 in pituitary GH.

Novel genes and variants associated with congenital pituitary hormone deficiency in the era of next-generation sequencing

Combined pituitary hormone deficiency (CPHD) is not a rare disorder, with a frequency of approximately 1 case per 4,000 live births. However, in most cases, a genetic diagnosis is not available. Furthermore, the diagnosis is challenging because no clear correlation exists between the pituitary hormones affected and the gene(s) responsible for the disorder. Next-generation sequencing (NGS) has recently been widely used to identify novel genes that cause (or putatively cause) CPHD. This review outlines causative genes for CPHD that have been newly reported in recent years. Moreover, novel variants of known CPHD-related genes (POU1F1 and GH1 genes) that contribute to CPHD through unique mechanisms are also discussed in this review. From a clinical perspective, variants in some of the recently identified causative genes result in extra-pituitary phenotypes. Clinical research on the related symptoms and basic research on pituitary formation may help in inferring the causative gene(s) of CPHD. Future NGS analysis of a large number of CPHD cases may reveal new genes related to pituitary development. Clarifying the causative genes of CPHD may help to understand the process of pituitary development. We hope that future innovations will lead to the identification of genes responsible for CPHD and pituitary development.

Architects of Pituitary Tumour Growth

The pituitary is a master gland responsible for the modulation of critical endocrine functions. Pituitary neuroendocrine tumours (PitNETs) display a considerable prevalence of 1/1106, frequently observed as benign solid tumours. PitNETs still represent a cause of important morbidity, due to hormonal systemic deregulation, with surgical, radiological or chronic treatment required for illness management. The apparent scarceness, uncommon behaviour and molecular features of PitNETs have resulted in a relatively slow progress in depicting their pathogenesis. An appropriate interpretation of different phenotypes or cellular outcomes during tumour growth is desirable, since histopathological characterization still remains the main option for prognosis elucidation. Improved knowledge obtained in recent decades about pituitary tumorigenesis has revealed that this process involves several cellular routes in addition to proliferation and death, with its modulation depending on many signalling pathways rather than being the result of abnormalities of a unique proliferation pathway, as sometimes presented. PitNETs can display intrinsic heterogeneity and cell subpopulations with diverse biological, genetic and epigenetic particularities, including tumorigenic potential. Hence, to obtain a better understanding of PitNET growth new approaches are required and the systematization of the available data, with the role of cell death programs, autophagy, stem cells, cellular senescence, mitochondrial function, metabolic reprogramming still being emerging fields in pituitary research. We envisage that through the combination of molecular, genetic and epigenetic data, together with the improved morphological, biochemical, physiological and metabolically knowledge on pituitary neoplastic potential accumulated in recent decades, tumour classification schemes will become more accurate regarding tumour origin, behaviour and plausible clinical results.

An Exploration of Non-Coding RNAs in Extracellular Vesicles Delivered by Swine Anterior Pituitary

Extracellular vesicles are lipid bilayer-delimited particles carrying proteins, lipids, and small RNAs. Previous studies have demonstrated that they had regulatory functions both physiologically and pathologically. However, information remains inadequate on extracellular vesicles from the anterior pituitary, a key endocrine organ in animals and humans. In this study, we separated and identified extracellular vesicles from the anterior pituitary of the Duroc swine model. Total RNA was extracted and RNA-seq was performed, followed by a comprehensive analysis of miRNAs, lncRNAs, and circRNAs. Resultantly, we obtained 416 miRNAs, 16,232 lncRNAs, and 495 circRNAs. Furthermore, GO and KEGG enrichment analysis showed that the ncRNAs in extracellular vesicles may participate in regulating intracellular signal transduction, cellular component organization or biogenesis, small molecule binding, and transferase activity. The cross-talk between them also suggested that they may play an important role in the signaling process and biological regulation. This is the first report of ncRNA data in the anterior pituitary extracellular vesicles from the duroc swine breed, which is a fundamental resource for exploring detailed functions of extracellular vesicles from the anterior pituitary.

The Role of MicroRNAs in Influencing Body Growth and Development

Body growth and development are regulated among others by genetic and epigenetic factors. MicroRNAs (miRNAs) are epigenetic regulators of gene expression that act at the post-transcriptional level, thereby exerting a strong influence on regulatory gene networks. Increasing studies suggest the importance of miRNAs in the regulation of the growth plate and growth hormone (GH)-insulin-like growth factor (IGF) axis during the life course in a broad spectrum of animal species, contributing to longitudinal growth. This review summarizes the role of miRNAs in regulating growth in different in vitro and in vivo models acting on GH, GH receptor (GHR), IGFs, and IGF1R genes besides current knowledge in humans, and highlights that this regulatory system is of importance for growth.

MicroRNA-7a2 Regulates Prolactin in Developing Lactotrophs and Prolactinoma Cells

Prolactin production is controlled by a complex and temporally dynamic network of factors. Despite this tightly coordinated system, pathological hyperprolactinemia is a common endocrine disorder that is often not understood, thereby highlighting the need to expand our molecular understanding of lactotroph cell regulation. MicroRNA-7 (miR-7) is the most highly expressed miRNA family in the pituitary gland and the loss of the miR-7 family member, miR-7a2, is sufficient to reduce prolactin gene expression in mice. Here, we used conditional loss-of-function and gain-of-function mouse models to characterize the function of miR-7a2 in lactotroph cells. We found that pituitary miR-7a2 expression undergoes developmental and sex hormone-dependent regulation. Unexpectedly, the loss of mir-7a2 induces a premature increase in prolactin expression and lactotroph abundance during embryonic development, followed by a gradual loss of prolactin into adulthood. On the other hand, lactotroph development is delayed in mice overexpressing miR-7a2. This regulation of lactotroph function by miR-7a2 involves complementary mechanisms in multiple cell populations. In mouse pituitary and rat prolactinoma cells, miR-7a2 represses its target Raf1, which promotes prolactin gene expression. These findings shed light on the complex regulation of prolactin production and may have implications for the physiological and pathological mechanisms underlying hyperprolactinemia.

The Relevance of MicroRNAs in the Pathogenesis and Prognosis of HCV-Disease: The Emergent Role of miR-17-92 in Cryoglobulinemic Vasculitis

Hepatitis C virus (HCV) is a major public health problem. HCV is a hepatotropic and lymphotropic virus that leads to hepatocellular carcinoma (HCC) and lymphoproliferative disorders such as cryoglobulinemic vasculitis (CV) and non-Hodgkin's lymphoma (NHL). The molecular mechanisms by which HCV induces these diseases are not fully understood. MicroRNAs (miRNAs) are small non-coding molecules that negatively regulate post-transcriptional gene expression by decreasing their target gene expression. We will attempt to summarize the current knowledge on the role of miRNAs in the HCV life cycle, HCV-related HCC, and lymphoproliferative disorders, focusing on both the functional effects of their deregulation as well as on their putative role as biomarkers, based on association analyses. We will also provide original new data regarding the miR 17-92 cluster in chronically infected HCV patients with and without lymphoproliferative disorders who underwent antiviral therapy. All of the cluster members were significantly upregulated in CV patients compared to patients without CV and significantly decreased in those who achieved vasculitis clinical remission after viral eradication. To conclude, miRNAs play an important role in HCV infection and related oncogenic processes, but their molecular pathways are not completely clear. In some cases, they may be potential therapeutic targets or non-invasive biomarkers of tumor progression.

Ectodermal Organ Development Is Regulated by a microRNA-26b-Lef-1-Wnt Signaling Axis

The developmental role of Lef-1 in ectodermal organs has been characterized using Lef-1 murine knockout models. We generated a Lef-1 conditional over-expression (COEL) mouse to determine the role of Lef-1 expression in epithelial structures at later stages of development after endogenous expression switches to the mesenchyme. Lef-1 over expression (OE) in the oral epithelium creates a new dental epithelial stem cell niche that significantly increases incisor growth. These data indicate that Lef-1 expression is switched off in the dental epithelial at early stages to maintain the stem cell niche and regulate incisor growth. Bioinformatics analyses indicated that miR-26b expression increased coinciding with decreased Lef-1 expression in the dental epithelium. We generated a murine model over-expressing miR-26b that targets endogenous Lef-1 expression and Lef-1-related developmental mechanisms. miR-26b OE mice have ectodermal organ defects including a lack of incisors, molars, and hair similar to the Lef-1 null mice. miR-26b OE rescues the Lef-1 OE phenotype demonstrating a critical genetic and developmental role for miR-26b in the temporal and spatial expression of Lef-1 in epithelial tissues. Lef-1 expression regulates Wnt signaling and Wnt target genes as well as cell proliferation mechanisms, while miR-26b OE reduced the levels of Wnt target gene expression. The extra stem cell compartment in the COEL mice expressed Lef-1 suggesting that Lef-1 is a stem cell factor, which was absent in the miR-26b OE/COEL rescue mice. This is the first demonstration of a microRNA OE mouse model that has ectodermal organ defects. These findings demonstrate that the levels of Lef-1 are critical for development and establish a role for miR-26b in the regulation of ectodermal organ development through the control of Lef-1 expression and an endogenous stem cell niche.

The effect of miR-10b on growth hormone in pituitary cells of Yanbian yellow cattle by somatostatin receptor 2

This study aimed to evaluate the effect of miR-10b on growth hormone (GH) in pituitary cells of Yanbian yellow cattle. According to analysis of GH and somatostatin receptor 2 (SSTR2) mRNA and protein expression levels, we found that miR-10b targeted 3'UTR of SSTR2. Compared with the negative control (NC) group, GH mRNA transcription and protein expression in pituitary cells of Yanbian yellow cattle were significantly increased by adding miR-10b mimics (p < .01), while these were significantly decreased by adding miR-10b inhibitor (p < .05); compared with the NC group, SSTR2 mRNA transcription and protein expression were significantly inhibited by the addition of miR-10b mimics (p < .01), while these were significantly increased by the addition of miR-10b inhibitor compared with the iNC group (p < .05). This study suggested that miR-10b could regulate GH level by regulating SSTR2 gene expression in pituitary cells of Yanbian yellow cattle.

Identification and Profiling of Pituitary microRNAs of Sheep during Anestrus and Estrus Stages

MicroRNAs (miRNAs) are a class of small non-coding RNAs, molecules of 21 to 25 nucleotides in length, that regulate gene expression by binding to their target mRNA and play a significant role in animal development. The expression and role of miRNAs in regulating sheep estrus, however, remain elusive. Transcriptome analysis is helpful to understand the biological roles of miRNAs in the pituitary gland of sheep. A sheep's pituitary gland has a significant difference between estrus and anestrus states. Here, we investigate the expression profiles of sheep anterior pituitary microRNAs (miRNAs) in two states, estrus and anestrus, using Illumina HiSeq-technology. This study identified a total of 199 miRNAs and 25 differentially expressed miRNAs in the estrus and anestrus pituitary gland in sheep. Reverse transcription quantitative-PCR (RT-qPCR) analysis shows six differentially (p < 0.05) expressed miRNAs, that are miR-143, miR-199a, miR-181a, miR-200a, miR-218, and miR-221 in both estrus and anestrus states. miRNAs containing estrus-related terms and pathways regulation are enriched using enrichment analysis from gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG). Moreover, we also envisioned a miRNA-mRNA interaction network to understand the function of miRNAs involved in the pituitary gland regulatory network. In conclusion, miRNA expression profiles in sheep pituitary gland in the anestrus and estrus deliver a theoretical basis for the study of pituitary gland biology in sheep.

MiR-130a-3p Inhibits PRL Expression and Is Associated With Heat Stress-Induced PRL Reduction

MicroRNAs (MiRNAs) play critical roles in the regulation of pituitary function. MiR-130a-3p has previously been found to be down-regulated in prolactinoma, but its roles in prolactin (PRL) regulation and the underlying mechanisms are still unclear. Heat stress has been shown to induce alteration of endocrine hormones and miRNAs expressions. However, there is limited information regarding the emerging roles of miRNAs in heat stress response. In this study, we transfected miR-130a-3p mimic into the pituitary adenoma cells (GH3 cells) to investigate the function of miR-130a-3p in regulating PRL. Our results showed that miR-130a-3p overexpression significantly decreased the PRL expression at both mRNA and protein levels. Subsequently, estrogen receptor α (ERα) was identified as a direct target of miR-130a-3p by bioinformatics prediction, luciferase reporter assay and western blotting assay. Furthermore, the inhibition of ERα caused by estrogen receptor antagonist significantly reduced the PRL expression. Overexpression of ERα rescued the suppressed expression of PRL caused by miR-130a-3p mimic. Besides, we also studied the effect of heat stress on PRL and miRNAs expressions. Interestingly, we found that heat stress reduced PRL and ERα expressions while it increased miR-130a-3p expression both in vitro and in vivo. Taken together, our results indicate that miR-130a-3p represses ERα by targeting its 3'UTR leading to a decrease in PRL expression, and miR-130a-3p is correlative with heat stress-induced PRL reduction, which provides a novel mechanism that miRNAs are involved in PRL regulation.

Hepatitis B and C virus infection and risk of haematological malignancies

Hepatitis B virus (HBV) and hepatitis C virus (HCV) are classified as oncogenic human viruses. Chronic HBV and HCV infections are associated with higher risk of haematological malignancy development. Direct and indirect oncogenic mechanisms have been demonstrated for both HBV and HCV in several studies. HCV and overt/occult HBV infections in patients with oncohaematological disease constitute an impediment and a threat during immunosuppressive chemotherapy treatment. We review the HBV and HCV oncogenic mechanisms and the impact and the safety of antiviral treatment in patients with haematological malignancies.

Stem Cells, Self-Renewal, and Lineage Commitment in the Endocrine System

The endocrine system coordinates a wide array of body functions mainly through secretion of hormones and their actions on target tissues. Over the last decades, a collective effort between developmental biologists, geneticists, and stem cell biologists has generated a wealth of knowledge related to the contribution of stem/progenitor cells to both organogenesis and self-renewal of endocrine organs. This review provides an up-to-date and comprehensive overview of the role of tissue stem cells in the development and self-renewal of endocrine organs. Pathways governing crucial steps in both development and stemness maintenance, and that are known to be frequently altered in a wide array of endocrine disorders, including cancer, are also described. Crucially, this plethora of information is being channeled into the development of potential new cell-based treatment modalities for endocrine-related illnesses, some of which have made it through clinical trials.

Genetics of Pituitary Tumours

Pituitary tumours are relatively common in the general population. Most often they occur sporadically, with somatic mutations accounting for a significant minority of somatotroph and corticotroph adenomas. Pituitary tumours can also develop secondary to germline mutations as part of a complex syndrome or as familial isolated pituitary adenomas. Tumours occurring in a familial setting may present at a younger age and can behave more aggressively with resistance to treatment. This chapter will focus on the genetics and molecular pathogenesis of pituitary tumours.

Roles of differential expression of miR-543-5p in GH regulation in rat anterior pituitary cells and GH3 cells

Growth hormone (GH) is an important hormone released by the pituitary gland that plays a key role in the growth and development of organisms. In our study, TargetScan analysis and the dual luciferase reporter assays were used to predict and screen for miRNAs that might act on the rat Gh1 gene, and we identified miR-543-5p. Then, the GH3 cell line and the primary rat pituitary cells were transfected with miRNA mimic, inhibitor, and siRNA. We detected the Gh1 gene expression and the GH secretion by real-time PCR and ELISAs, respectively, to verify the regulatory effect of miR-543-5p on GH secretion. The results showed that miR-543-5p can inhibit Gh1 mRNA expression and reduce GH secretion. MiR-543-5p inhibitor upregulated Gh1 mRNA expression and increased GH secretion compared with the negative control. In summary, miR-543-5p downregulates Gh1 expression, resulting in a decrease in GH synthesis and secretion, which demonstrates the important role of miRNAs in regulating GH and animal growth and development.

Comprehensive Expression Profiling Analysis of Pituitary Indicates that circRNA Participates in the Regulation of Sheep Estrus

The pituitary gland is the most important endocrine organ that mainly regulates animal estrus by controlling the hormones synthesis. There is a significant difference between the estrus state and anestrus state of sheep pituitary system. Here, we studied the circular RNA (circRNA) expression profiles of the anterior pituitary of estrus and anestrus sheep using RNA-seq technology. Through this study, we identified a total of 12,468 circRNAs and 9231 differentially expressed circRNAs in the estrus and anestrus pituitary system of sheep. We analyzed some differentially expressed circRNAs by reverse transcription quantitative-PCR (RT-qPCR), and some circRNAs were demonstrated using RNase-R+ resistance experiments. CircRNAs involving the regulation of estrus-related terms and pathways are enriched by using gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. In addition, we also predicted partial microRNA-circRNA interaction network for circRNAs that regulate sheep estrus. Overall, this study explored a potential substantial role played by circRNAs involved in pituitary regulation on sheep estrus and proposed new questions for further study.

FoxO6 regulates Hippo signaling and growth of the craniofacial complex

The mechanisms that regulate post-natal growth of the craniofacial complex and that ultimately determine the size and shape of our faces are not well understood. Hippo signaling is a general mechanism to control tissue growth and organ size, and although it is known that Hippo signaling functions in neural crest specification and patterning during embryogenesis and before birth, its specific role in postnatal craniofacial growth remains elusive. We have identified the transcription factor FoxO6 as an activator of Hippo signaling regulating neonatal growth of the face. During late stages of mouse development, FoxO6 is expressed specifically in craniofacial tissues and FoxO6-/- mice undergo expansion of the face, frontal cortex, olfactory component and skull. Enlargement of the mandible and maxilla and lengthening of the incisors in FoxO6-/- mice are associated with increases in cell proliferation. In vitro and in vivo studies demonstrated that FoxO6 activates Lats1 expression, thereby increasing Yap phosphorylation and activation of Hippo signaling. FoxO6-/- mice have significantly reduced Hippo Signaling caused by a decrease in Lats1 expression and decreases in Shh and Runx2 expression, suggesting that Shh and Runx2 are also linked to Hippo signaling. In vitro, FoxO6 activates Hippo reporter constructs and regulates cell proliferation. Furthermore PITX2, a regulator of Hippo signaling is associated with Axenfeld-Rieger Syndrome causing a flattened midface and we show that PITX2 activates FoxO6 expression. Craniofacial specific expression of FoxO6 postnatally regulates Hippo signaling and cell proliferation. Together, these results identify a FoxO6-Hippo regulatory pathway that controls skull growth, odontogenesis and face morphology.

DICER1 mutation and pituitary prolactinoma

A young woman carrying germline DICER1 mutation was discovered to have a pituitary microprolactinoma when she became amenorrhoic. The mutation was identified as a result of family screening following the early death of the patient’s daughter with ovarian cancer. The patient was in follow-up screening for thyroid disease, and investigations were initiated when she became amenorrhoic. MR scan revealed a 6 mm diameter pituitary microadenoma and raised prolactin. The prolactin was efficiently suppressed with low-dose cabergoline, and her menstrual cycles resumed. Dicer is an RNase enzyme, which is essential for processing small non-coding RNAs. These molecules play pleiotropic roles in regulating gene expression, by targeting mRNA sequences for degradation. DICER1 plays different roles depending on cell context, but is thought to be a functional tumour suppressor gene. Accordingly, germline mutation in one DICER1 allele is insufficient for oncogenesis, and a second hit on the other allele is required, as a result of postnatal somatic mutation. Loss of DICER1 is linked to multiple tumours, with prominent endocrine representation. Multinodular goitre is frequent, with increased risk of differentiated thyroid cancer. Rare, developmental pituitary tumours are reported, including pituitary blastoma, but not reports of functional pituitary adenomas. As DICER1 mutations are rare, case reports are the only means to identify new manifestations and to inform appropriate screening protocols.

Regulation of Pituitary Progenitor Differentiation by β-Catenin

The pituitary gland is a critical organ that is necessary for many physiological processes, including growth, reproduction, and stress response. The secretion of pituitary hormones from specific cell types regulates these essential processes. Pituitary hormone cell types arise from a common pool of pituitary progenitors, and mutations that disrupt the formation and differentiation of pituitary progenitors result in hypopituitarism. Canonical WNT signaling through CTNNB1 (β-catenin) is known to regulate the formation of the POU1F1 lineage of pituitary cell types. When β-catenin is deleted during the initial formation of the pituitary progenitors, Pou1f1 is not transcribed, which leads to the loss of the POU1F1 lineage. However, when β-catenin is deleted after lineage specification, there is no observable effect. Similarly, the generation of a β-catenin gain-of-function allele in early pituitary progenitors or stem cells results in the formation of craniopharyngiomas, whereas stimulating β-catenin in differentiated cell types has no effect. PROP1 is a pituitary-specific transcription factor, and the peak of PROP1 expression coincides with a critical time point in pituitary organogenesis-that is, after pituitary progenitor formation but before lineage specification. We used a Prop1-cre to conduct both loss- and gain-of-function studies on β-catenin during this critical time point. Our results demonstrate that pituitary progenitors remain sensitive to both loss and gain of β-catenin at this time point, and that either manipulation results in hypopituitarism.

Identification and comparison of microRNAs in pituitary gland during prenatal and postnatal stages of sheep by deep sequencing

MicroRNAs (miRNAs) are a class of short-chain RNA molecules of ~22 nucleotides in length and regulate gene expression at posttranscriptional levels by interacting with mRNAs. Although many miRNAs have been identified, the expression and function of miRNAs in the pituitary gland of sheep are still unclear. In this study, the identity and abundance of miRNAs were determined in the sheep pituitary gland of prenatal and postnatal stages. We showed that 107 miRNAs are significantly (P<0.05) differentially expressed in pituitary glands between the prenatal and postnatal stages, and 44 new miRNA candidates were found according to a series of filtration criteria. Reverse-transcription polymerase chain reaction (RT-PCR) and DNA sequencing analysis confirmed the presence of several miRNAs. Real-time RT-PCR analysis showed that sheep miRNAs were expressed in prenatal and postnatal pituitary glands. We found that miRNAs were involved in hormone synthesis, secretion and signalling pathway regulation by gene ontology (GO) and KEGG concentration analysis. Our study provides valuable resources for comprehensive investigation of miRNAs in the pituitary gland and biology of sheep.

A STUDY OF THE ROLE OF MICRORNA IN PITUITARY ADENOMA

MicroRNAs are a new class of small non-coding RNAs, a length of 18–22 nucleotides that play a decisive role as posttranscriptional regulators of gene expression. Due to the large number of genes, regulated microRNAs, microRNAs are involved in many cellular processes. The study of the impairment of the expression of the target genes of microRNA, often associated with changes in important biological characteristics, provides a significant understanding of the role of microRNAs in oncogenesis. New evidence suggests that aberrant microRNA expression or dysregulation of endogenous microRNAs affects the onset and development of tumors, including adenomas of the pituitary gland. In this review, the significance of some microRNAs in the pathology of the pituitary adenoma will be assessed, as well as data on the study of microRNAs as therapeutic targets and new biomarkers.

Age-Related Changes in MicroRNA in the Rat Pituitary and Potential Role in GH Regulation

The growth hormone/insulin-like growth factor 1 (GH/IGF-1) axis has recently been recognized as an important factor related to the longevity of many organisms. MicroRNAs (miRNAs or miRs) could also participate in diverse biological processes. However, the role of miRNAs in the decline of pituitary GH during the growth process remains unclear. To better characterize the effects of miRNAs on the pituitary, we used a miRNA microarray to investigate the miRNA profile in the rat pituitary from postnatal development throughout the growth process. Then, in vitro experiments were conducted to analyze the miRNAs' potential roles related to GH regulation. Taken together, the microarray results indicated that there were 22 miRNAs differentially expressed during pituitary development. The bioinformatics analysis suggested that the most differentially expressed miRNAs may participate in multiple pathways associated with the pituitary function. Furthermore, the in vitro findings demonstrated that miR-141-3p was involved in GH regulation.

Roles of differential expression of microRNA-21-3p and microRNA-433 in FSH regulation in rat anterior pituitary cells

Follicle-stimulating hormone (FSH) secreted by adenohypophyseal cells plays an important role in the regulation of reproduction, but whether microRNAs (miRNAs) regulate the secretion of FSH remains unclear. In the present study, we predicted and screened miRNAs that might act on the follicle-stimulating hormone beta-subunit (FSHb) gene of rats using the TargetScan program and luciferase reporter assays, and the results identified two miRNAs, miR-21-3p and miR-433. We then transfected these miRNAs into rat anterior adenohypophyseal cells and assessed the FSHb expression levels in and FSH secretion by the transfected cells through quantitative PCR and ELISA. The results showed that both miR-21-3p and miR-433 down-regulated the expression levels of FSHb and resulted in the decrease of the secretion of FSH compared with the control group, and treatment with miR-21-3p and miR-433 inhibitors up-regulated the expression levels of FSHb and resulted in the increase of the secretion of FSH. Taken together, our results indicate that miR-21-3p and miR-433 can down-regulate the expression of FSHb by directly targeting the FSHb 3′UTR in rat primary pituitary cells. Our findings provide evidence that miRNAs can regulate FSHb expression and further affect the secretion of FSH and might contribute to the use of miRNAs for the regulation of animal reproduction.

Regulation of FSH expression by differentially expressed miR-186-5p in rat anterior adenohypophyseal cells

Follicle-stimulating hormone (FSH) has key roles in animal reproduction, including spermatogenesis and ovarian maturation. Many factors influence FSH secretion. However, despite the broad functions of microRNAs (miRNAs) via the regulation of target genes, little is known about their roles in FSH secretion. Our previous results suggested that miR-186-5p targets the 3′ UTR of FSHb; therefore, we examined whether miR-186-5p could regulate FSH secretion in rat anterior adenohypophyseal cells. miR-186-5p was transfected into rat anterior pituitary cells. The expression of FSHb and the secretion of FSH were examined by RT-qPCR and ELISA. A miR-186-5p mimic decreased the expression of FSHb compared with expression in the control group and decreased FSH secretion. In contrast, both the mRNA levels and secretion of FSH increased in response to miR-186-5p inhibitors. Our results demonstrate that miR-186-5p regulates FSH secretion by directly targeting the FSHb 3′ UTR, providing additional functional evidence for the importance of miRNAs in the regulation of animal reproduction.

MicroRNAs in pituitary tumors

Since the presence of microRNAs was first observed in normal pituitary, the majority of scientific publications addressing their role and the function of microRNAs in the pituitary have been based on pituitary tumor studies. In this review, we briefly describe the involvement of microRNAs in the synthesis of pituitary hormones and we present a comprehensive inventory of microRNA suppressors and inducers of pituitary tumors. Finally, we summarize the functional role of microRNAs in tumorigenesis, progression and aggressiveness of pituitary tumors, mechanisms contributing to the regulation (transcription factors, genomic modifications or epigenetic) or modulation (pharmacological treatment) of microRNAs in these tumors, and the interest of thoroughly studying the expression of miRNAs in body fluids.

Limitations of high throughput methods for miRNA expression profiles in non-functioning pituitary adenomas

Microarray, RT-qPCR based arrays and next-generation-sequencing (NGS) are available high-throughput methods for miRNA profiling (miRNome). Analytical and biological performance of these methods were tested in identification of biologically relevant miRNAs in non-functioning pituitary adenomas (NFPA). miRNome of 4 normal pituitary (NP) and 8 NFPA samples was determined by these platforms and expression of 21 individual miRNAs was measured on 30 (20 NFPA and 10 NP) independent samples. Complex bioinformatics was used. 132 and 137 miRNAs were detected by all three platforms in NP and NFPA, respectively, of which 25 were differentially expressed (fold change > 2). The strongest correlation was observed between microarray and TaqMan-array, while the data obtained by NGS were the most discordant despite of various bioinformatics settings. As a technical validation we measured the expression of 21 selected miRNAs by individual RT-qPCR and we were able to validate 35.1%, 76.2% and 71.4% of the miRNAs revealed by SOLiD, TLDA and microarray result, respectively. We performed biological validation using an extended number of samples (20 NFPAs and 8 NPs). Technical and biological validation showed high correlation (p < 0.001; R = 0.96). Pathway and network analysis revealed several common pathways but no pathway showed the same activation score. Using the 25 platform-independent miRNAs developmental pathways were the top functional categories relevant for NFPA genesis. The difference among high-throughput platforms is of great importance and selection of screening method can influence experimental results. Validation by another platform is essential in order to avoid or to minimalize the platform specific errors.

miR-361-3p regulates FSH by targeting FSHB in a porcine anterior pituitary cell model

FSH plays an essential role in processes involved in human reproduction, including spermatogenesis and the ovarian cycle. While the transcriptional regulatory mechanisms underlying its synthesis and secretion have been extensively studied, little is known about its posttranscriptional regulation. A bioinformatics analysis from our group indicated that a microRNA (miRNA; miR-361-3p) could regulate FSH secretion by potentially targeting the FSHB subunit. Herein, we sought to confirm these findings by investigating the miR-361-3p-mediated regulation of FSH production in primary pig anterior pituitary cells. Gonadotropin-releasing hormone (GnRH) treatment resulted in an increase in FSHB synthesis at both the mRNA, protein/hormone level, along with a significant decrease in miR-361-3p and its precursor (pre-miR-361) levels in time- and dose-dependent manner. Using the Dual-Luciferase Assay, we confirmed that miR-361-3p directly targets FSHB. Additionally, overexpression of miR-361-3p using mimics significantly decreased the FSHB production at both the mRNA and protein levels, with a reduction in both protein synthesis and secretion. Conversely, both synthesis and secretion were significantly increased following miR-361-3p blockade. To confirm that miR-361-3p targets FSHB, we designed FSH-targeted siRNAs, and co-transfected anterior pituitary cells with both the siRNA and miR-361-3p inhibitors. Our results indicated that the siRNA blocked the miR-361-3p inhibitor-mediated upregulation of FSH, while no significant effect on non-target expression. Taken together, our results demonstrate that miR-361-3p negatively regulates FSH synthesis and secretion by targeting FSHB, which provides more functional evidence that a miRNA is involved in the direct regulation of FSH.

Strategies to use microRNAs as therapeutic targets

MicroRNAs (miRNAs) are non-coding RNAs generated from endogenous hairpin-shaped transcripts that powerfully regulate gene expression at post-transcriptional level. Each miRNA is capable to regulate the expression levels of hundreds of transcripts and each mRNA may have more than one miRNA recognition sequence. There is emerging evidence that deregulation of miRNA expression leads to the alteration of pivotal physiological functions contributing to the development of diseases and neoplasms, including pituitary adenoma. This review is aimed at providing the up-to-date knowledge concerning deregulated miRNAs of pituitary tumors and their functions. In order to take stock, pituitary tumors have been sub-divided in different classes on the basis of tumor features (histotype, dimension, aggressiveness). The overview takes full consideration of the recent advances in miRNAs role as potential therapeutics and biomarkers.

Disruption of STAT5b-Regulated Sexual Dimorphism of the Liver Transcriptome by Diverse Factors Is a Common Event

Signal transducer and activator of transcription 5b (STAT5b) is a growth hormone (GH)-activated transcription factor and a master regulator of sexually dimorphic gene expression in the liver. Disruption of the GH hypothalamo-pituitary-liver axis controlling STAT5b activation can lead to metabolic dysregulation, steatosis, and liver cancer. Computational approaches were developed to identify factors that disrupt STAT5b function in a mouse liver gene expression compendium. A biomarker comprised of 144 STAT5b-dependent genes was derived using comparisons between wild-type male and wild-type female mice and between STAT5b-null and wild-type mice. Correlations between the STAT5b biomarker gene set and a test set comprised of expression datasets (biosets) with known effects on STAT5b function were evaluated using a rank-based test (the Running Fisher algorithm). Using a similarity p-value ≤ 10(-4), the test achieved a balanced accuracy of 99% and 97% for detection of STAT5b activation or STAT5b suppression, respectively. The STAT5b biomarker gene set was then used to identify factors that activate (masculinize) or suppress (feminize) STAT5b function in an annotated mouse liver and primary hepatocyte gene expression compendium of ~1,850 datasets. Disruption of GH-regulated STAT5b is a common phenomenon in liver in vivo, with 5% and 29% of the male datasets, and 11% and 13% of the female datasets, associated with masculinization or feminization, respectively. As expected, liver STAT5b activation/masculinization occurred at puberty and suppression/feminization occurred during aging and in mutant mice with defects in GH signaling. A total of 70 genes were identified that have effects on STAT5b activation in genetic models in which the gene was inactivated or overexpressed. Other factors that affected liver STAT5b function were shown to include fasting, caloric restriction and infections. Together, these findings identify diverse factors that perturb the hypothalamo-pituitary-liver GH axis and disrupt GH-dependent STAT5b activation in mouse liver.

A new plasmid-based microRNA inhibitor system that inhibits microRNA families in transgenic mice and cells: a potential new therapeutic reagent

Current tools for the inhibition of microRNA (miR) function are limited to modified antisense oligonucleotides, sponges and decoy RNA molecules and none have been used to understand miR function during development. CRISPR/Cas-mediated deletion of miR sequences within the genome requires multiple chromosomal deletions to remove all functional miR family members because of duplications. Here, we report a novel plasmid-based miR inhibitor system (PMIS) that expresses a new RNA molecule, which inhibits miR family members in cells and mice. The PMIS engineered RNA optimal secondary structure, flanking sequences and specific antisense miR oligonucleotide sequence bind the miR in a stable complex to inhibit miR activity. In cells, one PMIS can effectively inhibit miR family members that share the same seed sequence. The PMIS shows no off-target effects or toxicity and is highly specific for miRs sharing identical seed sequences. Transgenic mice expressing both PMIS-miR-17-18 and PMIS-miR-19-92 show similar phenotypes of miR-17-92-knockout mice. Interestingly, mice only expressing PMIS-miR-17-18 have developmental defects distinct from mice only expressing PMIS-miR-19-92 demonstrating usefulness of the PMIS system to dissect different functions of miRs within clusters. Different PMIS miR inhibitors can be linked together to knock down multiple miRs expressed from different chromosomes. Inhibition of the miR-17-92, miR-106a-363 and miR-106b-25 clusters reveals new mechanisms and developmental defects for these miRs. We report a new tool to dissect the role of miRs in development without genome editing, inhibit miR function in cells and as a potential new therapeutic reagent.

A Common Phenotype Polymorphism in Mammalian Brains Defined by Concomitant Production of Prolactin and Growth Hormone

Pituitary Prolactin (PRL) and Growth Hormone (GH) are separately controlled and sub-serve different purposes. Surprisingly, we demonstrate that extra-pituitary expression in the adult mammalian central nervous system (CNS) is coordinated at mRNA and protein levels. However this was not a uniform effect within populations, such that wide inter-individual variation was superimposed on coordinate PRL/GH expression. Up to 44% of individuals in healthy cohorts of mice and rats showed protein levels above the norm and coordinated expression of PRL and GH transcripts above baseline occurred in the amygdala, frontal lobe and hippocampus of 10% of human subjects. High levels of PRL and GH present in post mortem tissue were often presaged by altered responses in fear conditioning and stress induced hyperthermia behavioral tests. Our data define a common phenotype polymorphism in healthy mammalian brains, and, given the pleiotropic effects known for circulating PRL and GH, further consequences of coordinated CNS over-expression may await discovery.

A Pit-1 Binding Site Adjacent to E-box133 in the Rat PRL Promoter is Necessary for Pulsatile Gene Expression Activity

Recent evidence reveals that prolactin gene expression (PRL-GE) in mammotropes occurs in pulses, but the molecular process(es) underlying this phenomenon remains unclear. Earlier, we have identified an E-box (E-box133) in the rat PRL promoter that binds several circadian elements and is critical for this dynamic process. Preliminary analysis revealed a Pit-1 binding site (P2) located immediately adjacent to this E-box133 raising the possibility that some type of functional relationship may exist between these two promoter regions. In this study, using serum shocked GH3 cell culture system to synchronize PRL-GE activity, we determined that Pit-1 gene expression occurred in pulses with time phases similar to that for PRL. Interestingly, EMSA analysis not only confirmed Pit-1 binding to the P2 site, but also revealed an interaction with factor(s) binding to the adjacent E-box133 promoter element. Additionally, down-regulation of Pit-1 by siRNA reduced PRL levels during pulse periods. Thus, using multiple evidences, our results demonstrate clearly that the Pit-1 P2 site is necessary for PRL-GE elaboration. Furthermore, the proximity of this critical Pit-1 binding site (P2) and the E-box133 element coupled with the evidences of a site-to-site protein interactions suggest that the process of PRL-GE pulse activity might involve more dynamic and intricate cross-talks between promoter elements that may span some, or all, of the proximal region of the PRL promoter in driving its pulsatile expression.

Circulating miRNAs as biomarkers for endocrine disorders

Specific, sensitive and non-invasive biomarkers are always needed in endocrine disorders. miRNAs are short, non-coding RNA molecules with well-known role in gene expression regulation. They are frequently dysregulated in metabolic and endocrine diseases. Recently it has been shown that they are secreted into biofluids by nearly all kind of cell types. As they can be taken up by other cells they may have a role in a new kind of paracrine, cell-to-cell communication. Circulating miRNAs are protected by RNA-binding proteins or microvesicles hence they can be attractive candidates as diagnostic or prognostic biomarkers. In this review, we summarize the characteristics of extracellular miRNA's and our knowledge about their origin and potential roles in endocrine and metabolic diseases. Discussions about the technical challenges occurring during identification and measurement of extracellular miRNAs and future perspectives about their roles are also highlighted.

Expression of microRNA‑26b and identification of its target gene EphA2 in pituitary tissues in Yanbian cattle

microRNAs (miRNAs/miRs) are a class of single-stranded non-coding RNA molecules of 19–24 nucleotides (nt) in length. They are widely expressed in animals, plants, bacteria and viruses. Via specific mRNA complementary pairing of target genes, miRNAs are able to regulate the expression of mRNA levels or inhibit protein translation following transcription. miRNA expression has a time- and space specificity, and it is involved in cell proliferation and differentiation, apoptosis, development, tumor metastasis occurrence and other biological processes. miR-26b is an miRNA of 22 nt and is important in the regulation of cellular processes. With the advancement of molecular biology techniques in recent years, there have been extensive investigations into miR-26b. Numerous studies have observed that miR-26b is involved in early embryonic development, cell proliferation regulation, pituitary hormone secretion and other physiological activities. miRNAs are associated with the function of propagation. The present study used reverse transcription quantitative polymerase chain reaction to detect the relative expression levels of miR-26b in the pituitary tissue of Yanbian cattle at different developmental stages. The 2^−ΔΔCt method was used to calculate the relative gene expression levels. The miRNA target gene database TargetScan and RNA22 were used for prediction of the miR-26b target gene and selective recognition was also performed. The results demonstrated that miR-26b is expressed in the pituitary tissues of Yanbian cattle at 6 and 24 months of age. The relative expression levels of miR-26b in the pituitary tissues of 24-month-old Yanbian cattle were 2.41 times that of those in the six-month-old Yanbian cattle, demonstrating significant differences in the relative expression (P<0.01). The relative expression of the candidate target genes, EphA2 and miR-26b, exhibited the opposite expression pattern. The relative expression levels in the pituitary tissues of six-month-old Yanbian cattle were 3.34 times that of those in 24-month-old Yanbian cattle (P<0.01). There are miR-26b binding sites in the 3′-untranslated region (3′-UTR) of EphA2 in bovine, human, murine and other mammalian mRNAs, suggesting that the EphA2 gene may be a target gene of miR-26b. The results of a Luciferase reporter system assay revealed that miR-26b is able to suppress EphA2 expression at the transcription level. Following the site-directed mutagenesis of plasmid EphA2 3′-UTR pmirGLO-MUT- and miR-26b mimic-transfected HeLa cells, the dual-luciferase reporter gene assay revealed that there were three consecutive nucleotide mutations in the 3′-UTR, binding with the predicted seed region. This may have caused the miR-26b inhibition of luciferase activity to decrease from 60% in the wild-type to 26%, suggesting that miR-26b achieved its function via binding with the TACTTGAA sequence of the 3′-UTR in EphA2. In conclusion, the present study successfully assessed the expression pattern of miR-26b in the pituitary tissue of Yanbian cattle, and also confirmed that EphA2 was a target gene of miR-26b in Yanbian cattle in vitro. The present study provided the theoretical basis to further investigate the role of miR-26b in early embryonic development, pituitary hormone secretion and other reproductive functions.

Comparative Anterior Pituitary miRNA and mRNA Expression Profiles of Bama Minipigs and Landrace Pigs Reveal Potential Molecular Network Involved in Animal Postnatal Growth

The anterior pituitary is the most important endocrine organ modulating animal postnatal growth, mainly by controlling growth hormone (GH) gene transcription, synthesis, and secretion. As an ideal model for animal postnatal growth studies, the Bama minipig is characterized as having a lower growth performance and fewer individual differences compared with larger pig breeds. In this study, anterior pituitaries from Bama minipig and Landrace pig were used for miRNA and mRNA expression profile analysis using miRNA microarrays and mRNA-seq. Consequently, a total of 222 miRNAs and 12,909 transcripts were detected, and both miRNAs and mRNAs in the two breeds showed high correlation (r > 0.97). Additionally, 41 differentially expressed miRNAs and 2,254 transcripts were identified. Pathways analysis indicated that 32 pathways significantly differed in the two breeds. Importantly, two GH-regulation-signalling pathways, cAMP and inositol 1, 4, 5-triphosphate (IP3), and multiple GH-secretion-related transcripts were significantly down-regulated in Bama minipigs. Moreover, TargetScan and RNAHybrid algorithms were used for predicting differentially expressed miRNAs (DE miRNAs) and differentially expressed mRNAs (DE mRNAs) interaction. By examining their fold-changes, interestingly, most DE miRNA-DE mRNA target pairs (63.68-71.33%) presented negatively correlated expression pattern. A possible network among miRNAs, mRNAs, and GH-regulation pathways was also proposed. Among them, two miRNA-mRNA interactions (Y-47 targets FSHB; ssc-miR-133a-3p targets GNAI3) were validated by dual-luciferase assay. These data will be helpful in understanding the possible molecular mechanisms involved in animal postnatal growth.

Molecular and cellular pathogenesis of adamantinomatous craniopharyngioma

Adamantinomatous craniopharyngiomas (ACPs) are the most common pituitary tumours in children. Although histologically benign, these are clinically aggressive tumours, difficult to manage and associated with poor quality of life for the patients. Several human and mouse studies have provided unequivocal evidence that the over-activation of the WNT/β-catenin signalling pathway underlies the molecular aetiology of these tumours. Recently, research using genetically modified mouse models of human ACP have revealed a critical and unexpected non-cell autonomous role for pituitary stem cells in ACP tumourigenesis, which has expanded the cancer stem cell paradigm. As the result of this basic research, the pathogenesis of ACP is being unveiled, with promising implications for the development of novel treatments against these childhood neoplasms. These benign tumours may additionally represent a unique model to provide insights into the initial steps of oncogenesis.

Alteration of the miRNA expression profile in male porcine anterior pituitary cells in response to GHRH and CST and analysis of the potential roles for miRNAs in regulating GH

OBJECTIVE

Growth hormone releasing hormone (GHRH) is a major positive regulator of growth hormone (GH) in the anterior pituitary gland, while cortistatin's (CST) role is negative. miRNAs (microRNAs or miRs) are small RNA molecules modulating gene expression at the post-transcriptional level. However, little is known about the function of miRNAs in the regulation of GH synthesis and/or secretion. This study investigated potential functional miRNAs involved in GH secretion in the normal porcine pituitary.

DESIGN

Primary porcine anterior pituitary cells were cultivated and then treated with 10 nmol/L GHRH and 100 nmol/L CST, respectively. The effects of GHRH and CST on GH secretion were determined using RIA. miRNA microarrays were employed to analyze miRNA expression after treatment and then differentially expressed miRNAs were screened. Bioinformatics analysis was used to analyze the potential targets in growth hormone regulation of altered miRNAs. Furthermore, functional experiments were conducted to study the function of ssc-let-7c.

RESULTS

GHRH significantly promoted GH secretion, while CST suppressed GH secretion. 19 and 35 differentially expressed miRNAs were identified in response to GHRH and CST treatments respectively. Verification of 5 randomly selected miRNAs by quantitative real-time PCR (qRT-PCR) showed similar changes with microarray analysis. Target analysis showed that some miRNAs may be involved in GH secretion-related pathways. Importantly, ssc-let-7c was predicted to target GH1 and GHRHR mRNA 3'untranslated regions (3'UTRs), which was supported by luciferase reporter assay. Furthermore, functional experimental results showed that ssc-let-7c was involved in GH secretion regulation, and overexpression of ssc-let-7c inhibited GH secretion in porcine anterior pituitary cells.

CONCLUSIONS

GHRH and CST modulated porcine pituitary cell miRNA expression. Bioinformatics analysis revealed a complicated network among differentially expressed miRNAs, GH regulation-related genes and hormones. More interestingly, ssc-let-7c inhibited both GH1 and GHRHR mRNA 3'UTR reporter vectors' luciferase activity and overexpression of ssc-let-7c led to a decrease of GH secretion.

TBX1 protein interactions and microRNA-96-5p regulation controls cell proliferation during craniofacial and dental development: implications for 22q11.2 deletion syndrome

T-box transcription factor TBX1 is the major candidate gene for 22q11.2 deletion syndrome (22q11.2DS, DiGeorge syndrome/Velo-cardio-facial syndrome), whose phenotypes include craniofacial malformations such as dental defects and cleft palate. In this study, Tbx1 was conditionally deleted or over-expressed in the oral and dental epithelium to establish its role in odontogenesis and craniofacial developmental. Tbx1 lineage tracing experiments demonstrated a specific region of Tbx1-positive cells in the labial cervical loop (LaCL, stem cell niche). We found that Tbx1 conditional knockout (Tbx1(cKO)) mice featured microdontia, which coincides with decreased stem cell proliferation in the LaCL of Tbx1(cKO) mice. In contrast, Tbx1 over-expression increased dental epithelial progenitor cells in the LaCL. Furthermore, microRNA-96 (miR-96) repressed Tbx1 expression and Tbx1 repressed miR-96 expression, suggesting that miR-96 and Tbx1 work in a regulatory loop to maintain the correct levels of Tbx1. Cleft palate was observed in both conditional knockout and over-expression mice, consistent with the craniofacial/tooth defects associated with TBX1 deletion and the gene duplication that leads to 22q11.2DS. The biochemical analyses of TBX1 human mutations demonstrate functional differences in their transcriptional regulation of miR-96 and co-regulation of PITX2 activity. TBX1 interacts with PITX2 to negatively regulate PITX2 transcriptional activity and the TBX1 N-terminus is required for its repressive activity. Overall, our results indicate that Tbx1 regulates the proliferation of dental progenitor cells and craniofacial development through miR-96-5p and PITX2. Together, these data suggest a new molecular mechanism controlling pathogenesis of dental anomalies in human 22q11.2DS.