Effect of the interaction of metformin and bone morphogenetic proteins on ovarian steroidogenesis by human granulosa cells

Sex-biased TGFβ signalling in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare cardiovascular disorder leading to pulmonary hypertension and, often fatal, right heart failure. Sex differences in PAH are evident, which primarily presents with a female predominance and increased male severity. Disturbed signalling of the transforming growth factor-β (TGFβ) family and gene mutations in the bone morphogenetic protein receptor 2 (BMPR2) are risk factors for PAH development, but how sex-specific cues affect the TGFβ family signalling in PAH remains poorly understood. In this review, we aim to explore the sex bias in PAH by examining sex differences in the TGFβ signalling family through mechanistical and translational evidence. Sex hormones including oestrogens, progestogens, and androgens, can determine the expression of receptors (including BMPR2), ligands, and soluble antagonists within the TGFβ family in a tissue-specific manner. Furthermore, sex-related genetic processes, i.e. Y-chromosome expression and X-chromosome inactivation, can influence the TGFβ signalling family at multiple levels. Given the clinical and mechanistical similarities, we expect that the conclusions arising from this review may apply also to hereditary haemorrhagic telangiectasia (HHT), a rare vascular disorder affecting the TGFβ signalling family pathway. In summary, we anticipate that investigating the TGFβ signalling family in a sex-specific manner will contribute to further understand the underlying processes leading to PAH and likely HHT.

Stimulatory effects of vasopressin on progesterone production and BMP signaling by ovarian granulosa cells

The aim of the present study was to clarify the effects of arginine vasopressin (AVP) on ovarian steroid production and its functional relationship to the ovarian bone morphogenetic protein (BMP) system. The results showed that AVP treatment significantly increased gonadotropin- and forskolin-induced progesterone synthesis by primary culture of rat granulosa cells and human granulosa cells, respectively. In contrast, estradiol production was not significantly affected by AVP. Treatment with AVP significantly increased forskolin-induced cAMP synthesis by human granulosa cells and mRNA levels of the progesterogenic enzymes CYP11A1 and HSD3B2 in the cells. On the other hand, AVP also enhanced BMP-15-induced phosphorylation of SMAD1/5/9 and ID1 transcription. It was further revealed that the expression levels of BMP receptors, including ALK3, ALK6 and BMPR2, were upregulated by AVP. Collectively, the results indicate that AVP stimulates progesterone production via the cAMP-PKA pathway with upregulation of BMP signaling that inhibits progesterone production, which may lead to fine adjustment of progesterone biosynthesis by granulosa cells.

Oxytocin enhances progesterone production with upregulation of BMP-15 activity by granulosa cells

To elucidate the reproductive role of oxytocin (OXT) in ovarian steroidogenesis and its functional interaction with bone morphogenetic proteins (BMPs), the effects of OXT on ovarian steroidogenesis were investigated by utilizing primary culture of rat granulosa cells and human granulosa KGN cells. Here we revealed that the OXT receptor was expressed in both rat and human granulosa cells and that OXT treatment significantly increased follicle-stimulating hormone (FSH)- and forskolin (FSK)-induced progesterone production, but not estradiol production, by rat and human granulosa cells, respectively. In accordance with the effects of OXT on progesterone production, OXT enhanced mRNA expression of CYP11A1 and HSD3B2 induced by FSK in human granulosa cells. Of note, OXT enhanced the phosphorylation of SMAD1/5/9 and the transcription of ID1 induced by BMP-15, but not those induced by BMP-6, in human granulosa cells. It was also revealed that OXT treatment upregulated the expression of BMPR2, a crucial type-II receptor of BMP-15, and enhanced the BMP-15-induced expression of inhibitory SMAD6 by human granulosa cells. Collectively, it was shown that OXT accelerates ovarian progesterone synthesis with upregulation of BMP-15 activity, leading to a fine-tuning of ovarian steroidogenesis (186 words).

Roles of NR5A1 and NR5A2 in the regulation of steroidogenesis by Clock gene and bone morphogenetic proteins by human granulosa cells

The functional role of the transcription factors NR5A1 and NR5A2 and their interaction with Clock gene and bone morphogenetic proteins (BMPs) were investigated in human granulosa KGN cells. Treatment with BMP-15 and GDF-9 suppressed forskolin (FSK)-induced steroidogenesis as shown by the mRNA expression levels of StAR and P450scc but not the mRNA expression level of P450arom. Of interest, treatment with BMP-15 and GDF-9 also suppressed FSK-induced NR5A2 mRNA expression. Treatment with BMP-15 suppressed NR5A2 mRNA and protein expression but increased Clock mRNA and protein expression levels by granulosa cells. The mRNA expression levels of NR5A1, but not those of NR5A2, were positively correlated with the levels of Clock mRNA, while the mRNA levels of Id-1, the target gene of BMP signaling, were positively correlated with those of NR5A1 but not with those of NR5A2. It was also demonstrated that the mRNA expression levels of NR5A1 were positively correlated with those of P450arom and 3βHSD, whereas the mRNA expression level of NR5A2 was correlated with those of StAR and P450scc. Furthermore, inhibition of Clock gene expression by siRNA attenuated the expression of NR5A1, and the mRNA levels of Clock gene were significantly correlated with those of NR5A1. Collectively, the results suggested a novel mechanism by which Clock gene expression induced by BMP-15 is functionally linked to the expression of NR5A1, whereas NR5A2 expression is suppressed by BMP-15 in granulosa cells. The interaction between Clock NR5A1/NR5A2 and BMP-15 is likely to be involved in the fine-tuning of steroidogenesis by ovarian granulosa cells.

Metformin Reduces Vascular Assembly in High Glucose-Treated Human Microvascular Endothelial Cells in An AMPK-Independent Manner

Objective

The aim is to examine the effect of metformin in human microvascular endothelial cells exposed to high glucose (HG) concentration and compare them with the effects of other 5' adenosine monophosphate-activated protein kinase (AMPK) modulators under the same condition.

Materials and Methods

In this experimental study, human microvascular endothelial cells (HMECs) were treated with 15 mM metformin, 1 mM 5-aminoimidazol-4-carboxamideribonucleotide (AICAR) and 10 mM compound C in the presence of 20 mM glucose (hyperglycemic condition). Migration, invasion and proliferation were evaluated as well as the capillary-like structures formation. Moreover, the expression of angiogenic genes was assessed.

Results

Metformin significantly inhibited vessel formation and migration, although it did not change HMECs proliferation and invasion. In addition, metformin significantly reduced collagen formation as evidenced by histological staining. Concomitantly, expression of several genes implicated in angiogenesis and fibrosis, namely TGFß2, VEGFR2, ALK1, JAG1, TIMP2, SMAD5, SMAD6 and SMAD7, was slightly upregulated. Immunostaining for proteins involved in ALK5 receptor signaling, the alternative TGFß signaling pathway, revealed significant differences in SMAD2/3 expression.

Conclusion

Our data showed that metformin prevents vessel assembly in HMECs, probably through an AMPK- independent mechanism. Understanding the molecular mechanisms by which this pharmacological agent affects endothelial dysfunction is of paramount importance and paves the way to its particular use in preventing development of diabetic retinopathy and nephropathy, two processes where angiogenesis is exacerbated.

Estradiol Upregulates the Expression of the TGF-β Receptors ALK5 and BMPR2 during the Gonadal Development of Schizothorax prenanti

Simple Summary

Schizothorax prenanti, known as the ya-fish, is mainly distributed in regions adjacent to the Qinghai-Tibet Plateau (QTP) and is an endemic fish species with great economic importance in aquaculture in Western China. In the present study, we were aimed to explore the functions of ALK5 and BMPR2 during the gonadal development of S. prenanti. Our results suggest that ALK5 and BMPR2 may play a potentially vital role in both folliculogenesis and spermatogenesis in S. prenanti.

Abstract

TGF-β receptors play important roles in mediating TGF-β signals during gonadal development. To identify the functions of TGF-β receptors, including the type I receptor (activin receptor-like kinase 5, ALK5) and type II receptor (bone morphogenetic protein receptor 2, BMPR2), during the gonadal development of S. prenanti, the full-length cDNA sequences of ALK5 and BMPR2 were isolated and characterized. Their expression patterns in developing gonads and in the gonads of exogenous estradiol (E₂) -fed fish were analyzed. The cDNAs of ALK5 and BMPR2 were 1925 bp and 3704 bp in length and encoded 501 and 1070 amino acid residues, respectively. ALK5 and BMPR2 were mostly expressed in gonads, particularly in cortical alveoli stage ovaries and mid-spermatogenic stage testes; however, the overall level of BMPR2 mRNA was higher than that of ALK5 during gonadal development. Furthermore, immunohistochemical signals of ALK5 and BMPR2 were mostly detected at chromatin nucleolar oocytes and perinuclear oocytes in ovaries and at spermatocytes and spermatogonia in testes. Exogenous E₂ induces the gonadal expression of ALK5 and BMPR2, and BMPR2 is more responsive to E₂ than ALK5. These results suggest that ALK5 and BMPR2 might play a potentially vital role in both folliculogenesis and spermatogenesis in S. prenanti.

Effects of TG interaction factor 1 on synthesis of estradiol and progesterone in granulosa cells of goats through SMAD2/3-SP1 signaling pathway

The TG interaction factor 1 (TGIF1) is of the TALE homologue domain protein family and is considered as a transcriptional repressor of SMAD protein that interacts with DNA through a specific consensus-binding site for TG and recruits mSin3A and histone deacetylases to the SMAD complex. In this study, there is the first detailed description of TGIF1 on steroidogenesis in goat granulosa cells. When there is a relatively greater expression of the TGIF1 gene, there is a lesser abundance of CYP11A1, CYP19A1, and StAR mRNA transcript and protein and 3β-HSD mRNA transcript in granulosa cells of goats. Furthermore, there were lesser concentrations of 17β-estradiol (E₂) and progesterone (P₄) in culture medium when there was greater TGIF1 gene expression and there were greater concentrations of these hormones in the culture medium when there was lesser TGIF1 gene expression. There may be functions of TGIF1, therefore, in suppression of SMAD-induced E₂ and P₄ production and in decreasing the phosphorylation of SMAD2/3 in granulosa cells of goats and relative abundance of the SMAD2/3 protein transcription factor, SP1. With suppression of TGIF1 gene expression, there was a reversal of SP1-induced suppression of steroidogenesis-related genes. Results of the present study provide insights about the potential mechanism underlying the regulation of granulosa cell steroidogenesis of goats by TGIF1.

Effects of atorvastatin and metformin on development of pentylenetetrazole-induced seizure in mice

Recent studies have shown that statins and Metformin may have beneficial effects on seizure through different mechanisms. In the current study, we investigated whether Metformin, Atorvastatin, and concomitant uses of them have beneficial effects on pentylenetetrazole (PTZ)-induced kindling. Adult male C57BL/6 mice were randomly divided into four experimental groups with seven mice in each group. Group 1, control group; group 2, received Metformin (200 mg/kg, i.p); group 3, received Atorvastatin (10 mg/kg, i.p.); group 4, received Atorvastatin (10 mg/kg, i.p.) plus Metformin (200 mg/kg, i.p.). Twenty minutes after injection of the mentioned drugs, the experimented mice received 37/5 mg/kg of PTZ intraperitoneally on alternating days. Then the convulsive behavior signs were evaluated for 20 min after each PTZ injection. There were significant differences in the stage 2 latency parameter among group 2 (p = 0.033, F = 8.46)/group 3 (p = 0.032, F = 10.42)/group 4 (p = 0.008, F = 24.57) as compared to the control group, while no significant differences were found comparing only group 2,3, and 4 with eachother excluding the control group. Pretreatment with Atorvastatin (p = 0.002, F = 33), Atorvastatin + Metformin (p = 0.006, F = 20.77), and Metformin alone increased stage 5 latency as compared to the PTZ group, significantly. Also, our results have shown that pretreatment with Atorvastatin (p = 0.013, F = 14.48), Metformin (p = 0.015, F = 16.67), and concomitant usage of them significantly decreased stage 5 duration as compared to the control group. Our findings clearly demonstrate that concomitant use of Metformin and Atorvastatin has no more protective effect against the development of kindling as compare to these drugs alone. Thus, we concluded that, these drugs may inhibit kindling via a similar mechanism and we suggested that it is probably through regulation of autophagy.

Interaction of ovarian steroidogenesis and clock gene expression modulated by bone morphogenetic protein-7 in human granulosa cells

A functional link between clock gene expression and ovarian steroidogenesis was studied using human granulosa KGN cells. Similarities between changes in the mRNA and protein expression levels of Bmal1 and Clock and those of Per2 and Cry1 were found in KGN cells after treatment with forskolin. Among the interrelationships between the expression levels of clock and steroidogenic factors, Clock mRNA had a strongly positive correlation with P450arom and a negative correlation with 3βHSD. Knockdown of Clock gene by siRNA resulted in a significant reduction of estradiol production by inhibiting P450arom expression, while it induced a significant increase of progesterone production by upregulating 3βHSD in KGN cells treated with forskolin. Moreover, BMP-7 had an enhancing effect on the expression of Clock mRNA and protein in KGN cells. Thus, the expression levels of Clock, being upregulated by forskolin and BMP-7, were functionally linked to estradiol production and progesterone suppression by human granulosa cells.

Consequences of BMPR2 Deficiency in the Pulmonary Vasculature and Beyond: Contributions to Pulmonary Arterial Hypertension

Since its association with familial pulmonary arterial hypertension (PAH) in 2000, Bone Morphogenetic Protein Receptor II (BMPR2) and its related signaling pathway have become recognized as a key regulator of pulmonary vascular homeostasis. Herein, we define BMPR2 deficiency as either an inactivation of the receptor, decreased receptor expression, or an impairment of the receptor’s downstream signaling pathway. Although traditionally the phenotypic consequences of BMPR2 deficiency in PAH have been thought to be limited to the pulmonary vasculature, there is evidence that abnormalities in BMPR2 signaling may have consequences in many other organ systems and cellular compartments. Revisiting how BMPR2 functions throughout health and disease in cells and organs beyond the lung vasculature may provide insight into the contribution of these organ systems to PAH pathogenesis as well as the potential systemic manifestation of PAH. Here we review our knowledge of the consequences of BMPR2 deficiency across multiple organ systems.