Serum And Glucocorticoid-regulated Kinase 1 Expression Research Articles

Combined Effects of Polystyrene Nanosphere and Homosolate Exposures on Estrogenic End Points in MCF-7 Cells and Zebrafish.

Micro- and nanoplastics (MNPs) and homosalate (HMS) are ubiquitous emerging environmental contaminants detected in human samples. Despite the well-established endocrine-disrupting effects (EDEs) of HMS, the interaction between MNPs and HMS and its impact on HMS-induced EDEs remain unclear. This study aimed to investigate the influence of MNPs on HMS-induced estrogenic effects and elucidate the underlying mechanisms in vitro and invivo. We assessed the impact of polystyrene nanospheres (PNSs; , ) on HMS-induced MCF-7 cell proliferation (HMS: , equivalent to ) using the E-SCREEN assay and explored potential mechanisms through transcriptomics. Adult zebrafish were exposed to HMS () with or without PNSs (, ) for 21 d. EDEs were evaluated through gonadal histopathology, fertility tests, steroid hormone synthesis, and gene expression changes in the hypothalamus-pituitary-gonad-liver (HPGL) axis. Coexposure of HMS and PNSs resulted in higher expression of estrogen receptor (ESR1) and the mRNAs of target genes (pS2, AREG, and PGR), a greater estrogen-responsive element transactivation activity, and synergistic stimulation on MCF-7 cell proliferation. Knockdown of serum and glucocorticoid-regulated kinase 1 (SGK1) rescued the MCF-7 cell proliferation induced by PNSs alone or in combination with HMS. In zebrafish, coexposure showed higher expression of SGK1 and promoted ovary development but inhibited spermatogenesis. In addition, coexposure led to lower egg hatchability, higher embryonic mortality, and greater larval malformation. Coexposure also modulated steroid hormone synthesis genes (cyp17a2, hsd17[Formula: see text]1, esr2b, vtg1, and vtg2), and resulted in higher () release in females. Conversely, males showed lower testosterone, , and gene expressions of cyp11a1, cyp11a2, cyp17a1, cyp17a2, and hsd17[Formula: see text]1. PNS exposure exacerbated HMS-induced estrogenic effects via SGK1 up-regulation in MCF-7 cells and disrupting the HPGL axis in zebrafish, with gender-specific patterns. This offers new mechanistic insights and health implications of MNP and contaminant coexposure. https://doi.org/10.1289/EHP13696.

SGK1 Target Genes Involved in Heart and Blood Vessel Functions in PC12 Cells.

Serum and glucocorticoid-regulated kinase 1 (SGK1) is expressed in neuronal cells and involved in the pathogenesis of hypertension and metabolic syndrome, regulation of neuronal function, and depression in the brain. This study aims to identify the cellular mechanisms and signaling pathways of SGK1 in neuronal cells. In this study, the SGK1 inhibitor GSK650394 is used to suppress SGK1 expression in PC12 cells using an in vitro neuroscience research platform. Comparative transcriptomic analysis was performed to investigate the effects of SGK1 inhibition in nervous cells using mRNA sequencing (RNA-seq), differentially expressed genes (DEGs), and gene enrichment analysis. In total, 12,627 genes were identified, including 675 and 2152 DEGs at 48 and 72 h after treatment with GSK650394 in PC12 cells, respectively. Gene enrichment analysis data indicated that SGK1 inhibition-induced DEGs were enriched in 94 and 173 genes associated with vascular development and functional regulation and were validated using real-time PCR, Western blotting, and GEPIA2. Therefore, this study uses RNA-seq, DEG analysis, and GEPIA2 correlation analysis to identify positive candidate genes and signaling pathways regulated by SGK1 in rat nervous cells, which will enable further exploration of the underlying molecular signaling mechanisms of SGK1 and provide new insights into neuromodulation in cardiovascular diseases.

Serum and glucocorticoid-regulated kinase 1: Structure, biological functions, and its inhibitors.

Serum and glucocorticoid-regulated kinase 1 (SGK1) is a serine/threonine kinase belonging to the protein kinase A, G, and C (AGC) family. Upon initiation of the phosphoinositide 3-kinase (PI3K) signaling pathway, mammalian target of rapamycin complex 2 (mTORC2) and phosphoinositide-dependent protein kinase 1 (PDK1) phosphorylate the hydrophobic motif and kinase domain of SGK1, respectively, inducing SGK1 activation. SGK1 modulates essential cellular processes such as proliferation, survival, and apoptosis. Hence, dysregulated SGK1 expression can result in multiple diseases, including hypertension, cancer, autoimmunity, and neurodegenerative disorders. This review provides a current understanding of SGK1, particularly in sodium transport, cancer progression, and autoimmunity. In addition, we summarize the developmental status of SGK1 inhibitors, their structures, and respective potencies evaluated in pre-clinical experimental settings. Collectively, this review highlights the significance of SGK1 and proposes SGK1 inhibitors as potential drugs for treatment of clinically relevant diseases.

Dapagliflozin attenuates diabetes-induced diastolic dysfunction and cardiac fibrosis by regulating SGK1 signaling

BackgroundRecent studies have reported improved diastolic function in patients administered sodium-glucose cotransporter 2 inhibitors (SGLT2i). We aimed to investigate the effect of dapagliflozin on left ventricular (LV) diastolic function in a diabetic animal model and to determine the molecular and cellular mechanisms underlying its function.MethodsA total of 30 male New Zealand white rabbits were randomized into control, diabetes, or diabetes+dapagliflozin groups (n = 10/per each group). Diabetes was induced by intravenous alloxan. Cardiac function was evaluated using echocardiography. Myocardial samples were obtained for histologic and molecular evaluation. For cellular evaluation, fibrosis-induced cardiomyoblast (H9C2) cells were obtained, and transfection was performed for mechanism analysis (serum and glucocorticoid-regulated kinase 1 (SGK1) signaling analysis).ResultsThe diabetes+dapagliflozin group showed attenuation of diastolic dysfunction compared with the diabetes group. Dapagliflozin inhibited myocardial fibrosis via inhibition of SGK1 and epithelial sodium channel (ENaC) protein, which was observed both in myocardial tissue and H9C2 cells. In addition, dapagliflozin showed an anti-inflammatory effect and ameliorated mitochondrial disruption. Inhibition of SGK1 expression by siRNA decreased and ENaC and Na+/H+ exchanger isoform 1 (NHE1) expression was confirmed as significantly reduced as siSGK1 in the diabetes+dapagliflozin group.ConclusionsDapagliflozin attenuated left ventricular diastolic dysfunction and cardiac fibrosis via regulation of SGK1 signaling. Dapagliflozin also reduced macrophages and inflammatory proteins and ameliorated mitochondrial disruption.

Estrogen-increased SGK1 Promotes Endometrial Stromal Cell Invasion in Adenomyosis by Regulating with LPAR2.

Adenomyosis is an estrogen-dependent gynecological disorder. The abnormal migration and invasion of the eutopic endometrium is thought to be the primary role in the pathogenesis of adenomyosis. However, the exact underlying mechanism remains unclear. This study investigated involvement of serum and glucocorticoid-regulated kinase 1 (SGK1) in the pathogenesis of adenomyosis. The SGK1 expression level was higher in the eutopic endometrium of adenomyosis. Upregulation of SGK1 can promote the migration, invasion of human stromal endometrial cells (HESC). Through RNA sequencing and other technical methods, we found that SGK1 regulates the expression of the important downstream molecule Lysophosphatidic acid receptor 2 (LPAR2), and ultimately regulates the expression level of functional proteins such as matrix metalloproteinase 2 and matrix metalloproteinase 9, which are related to migration and invasion. Then, we found that 17β-estradiol (E2) upregulated the expression of SGK1 in endometrial cells in a dose-dependent manner. Furthermore, SGK1 shRNA significantly suppressed the migration and invasion induced by E2 in endometrial cells, as well as the related factors. Our study revealed the possible role of SGK1 in the migration and invasion in the development of adenomyosis.

SGK1 regulated apoptosis in invasive breast carcinoma.

e13061 Background: Worldwide, breast cancer is the most common type of cancers and the presentation of drug resistance is often associated with poor prognosis. Previous studies have shown the mechanism of drug resistance was affected by apoptosis at different levels in the signaling cascades. This article is aimed to explore the relationship between the serum and glucocorticoid-regulated kinase 1 (SGK1) and apoptosis in invasive breast cancer (IBC). Methods: We evaluated the expression of SGK1 in IBC using publicly available data from The Cancer Genome Atlas (TCGA) and Curtis Breast program. TaqMan probe-based qRT-PCR assay and Western Blot analysis were performed to quantitatively detect the expression of SGK1 at RNA and protein levels in the IBC specimens. Clinicopathologic characteristics associated with overall survival were tested by Cox regression. Gene Set Enrichment Analysis (GSEA) was performed to mine the biological pathways involved in IBC pathogenesis related SGK1 regulatory network using MSigDB database. Immunohistochemistry staining (IHC) was used to detect apoptotic markers Fas, Bcl2 and SGK1 in the IBC specimens. Results: Totally 1109 IBC samples with SGK1 expression data were downloaded from TCGA databases for analyzed. SGK1 expression was elevated in normal breast tissues compared with both invasive ductal carcinoma and invasive lobular carcinoma (p < 0.0001). Among them, SKG expression in 112 tumor tissues was significantly lower than that in paracancerous tissues, especially in advanced patients with TNM stage IV. Western Blot and qRT-PCR assay confirmed that SGK1 expression in IBC was distinctly lower than normal. The Kaplan-Meier survival analysis showed that decreased expression of SGK1 was significantly correlated with the clinical stage (p = 0.036). In Curtis Breast program, we further verified SGK1 gene expression was reduced in stage IV than stage I. The univariate analysis demonstrated that clinicopathologic variables associated with poor survival include age, advanced stage, lymph nodes, distant metastasis and deep myometrial invasion. GSEA revealed that apoptosis was differentially enriched when SGK1 was highly expressed. Similarly, TCGA data indicated that the positive rate of SGK1 was higher in Fas positive IBCs, and the same result was also obtained by IHC in the IBC specimens. Conclusions: Expression of SGK1 regulated apoptosis in invasive breast carcinoma, which might be a potential therapeutic target to overcome refractory and drug-resistant breast cancer.

The Emerging Role of SGK1 (Serum- and Glucocorticoid-Regulated Kinase 1) in Major Depressive Disorder: Hypothesis and Mechanisms.

Major depressive disorder (MDD) is a heterogeneous psychiatric disease characterized by persistent low mood, diminished interests, and impaired cognitive and social functions. The multifactorial etiology of MDD is still largely unknown because of the complex genetic and environmental interactions involved. Therefore, no established mechanism can explain all the aspects of the disease. In this light, an extensive research about the pathophysiology of MDD has been carried out. Several pathogenic hypotheses, such as monoamines deficiency and neurobiological alterations in the stress-responsive system, including the hypothalamic–pituitary–adrenal (HPA) axis and the immune system, have been proposed for MDD. Over time, remarkable studies, mainly on preclinical rodent models, linked the serum- and glucocorticoid-regulated kinase 1 (SGK1) to the main features of MDD. SGK1 is a serine/threonine kinase belonging to the AGK Kinase family. SGK1 is ubiquitously expressed, which plays a pivotal role in the hormonal regulation of several ion channels, carriers, pumps, and transcription factors or regulators. SGK1 expression is modulated by cell stress and hormones, including gluco- and mineralocorticoids. Compelling evidence suggests that increased SGK1 expression or function is related to the pathogenic stress hypothesis of major depression. Therefore, the first part of the present review highlights the putative role of SGK1 as a critical mediator in the dysregulation of the HPA axis, observed under chronic stress conditions, and its controversial role in the neuroinflammation as well. The second part depicts the negative regulation exerted by SGK1 in the expression of both the brain-derived neurotrophic factor (BDNF) and the vascular endothelial growth factor (VEGF), resulting in an anti-neurogenic activity. Finally, the review focuses on the antidepressant-like effects of anti-oxidative nutraceuticals in several preclinical model of depression, resulting from the restoration of the physiological expression and/or activity of SGK1, which leads to an increase in neurogenesis. In summary, the purpose of this review is a systematic analysis of literature depicting SGK1 as molecular junction of the complex mechanisms underlying the MDD in an effort to suggest the kinase as a potential biomarker and strategic target in modern molecular antidepressant therapy.

SUN-LB93 Mineralocorticoid Receptor Mediates Sex-Dependent Anticontractile Effect of Perivascular Adipose Tissue in Obese Mice

Obesity, a condition of excessive fat mass and subclinical inflammation, reached epidemic proportions with higher prevalence in women compared to men worldwide. Expansion of the perivascular adipose tissue (PVAT) is observed in obesity and clinical studies indicate a positive correlation between PVAT amount and body mass index. PVAT, a fat depot surrounding most of the vessels, modulates vascular function by releasing PVAT-derived factors such as adipokines that exert anticontractile effect in health individuals. Despite sexual dimorphism on PVAT morphology, it is still unknown whether or not there is sex differences in the PVAT modulating vascular function in the setting of obesity. Aldosterone-mineralocorticoid receptor (MR) signaling pathway has been demonstrated to be adipogenic and proinflammatory in classical fat depots and treatment with MR antagonists (A) might reverse vascular dysfunction and remodeling in obese models, especially in female sex. Therefore, we aimed to evaluate the anticontractile effect of PVAT in male and female obese mice and hypothesized that MR signaling would be involved in possible sex differences in PVAT dysfunction in obesity. Male and female C57Bl6/J mice were fed a chow or a high-fat diet (HFD, 60% energy from fat) for 20 weeks. At the last 4 weeks of HFD, female and male mice were treated with the MRA spironolactone (Spi, 100 mg/kg/day). HFD feeding significantly increased body weight and visceral adipose tissue, which was not modified by Spi treatment in both sexes. Resistance mesenteric arteries were isolated with or without PVAT and mounted in a wire myograph to evaluate vascular contractile responses. Lean male and female mice PVAT had an anticontractile effect in the response to phenylephrine that was greater in females than males. The anticontractile effect of PVAT was significantly impaired in obese females but not modified in males. HFD-induced dysfunctional PVAT was prevented by Spi treatment in females. Next, we evaluated the protein expression of aldosterone-synthase CYP11B2, serum and glucocorticoid-regulated kinase 1 (SGK1), and epithelial sodium channel subunits (ENaCs) in isolated mesenteric PVAT of lean and obese male and female mice. There was an increased expression of CYP11B2, SGK1 and ENaCs only in obese female PVAT. Protein expression of adiponectin, a major PVAT-released adipokine was also increased in female mesenteric PVAT. In conclusion, the findings suggest sexual dimorphism in PVAT function in health and in obesity. Although anticontractile role of PVAT was exacerbated in lean female mice, female sex was more susceptible to develop PVAT dysfunction in the setting of obesity which was prevented by MR blockade. HFD-induced PVAT dysfunction in females was associated with increased expression of SGK1 and ENaCs. Therefore, data suggest MR activation as a mechanism mediating sex differences in PVAT dysfunction.FAPESP, CAPES.

Intracarotid cold saline infusion contributes to neuroprotection in MCAO‑induced ischemic stroke in rats via serum and glucocorticoid‑regulated kinase 1.

Intracarotid cold saline infusion (ICSI) brings about neuroprotective effects in ischemic stroke. However, the involvement of serum and glucocorticoid‑regulated kinase1 (SGK1) in the underlying mechanism of ICSI is not fully understood; therefore, we used the rat middle cerebral artery occlusion (MCAO) model to investigate the neuroprotective effects of ICSI on ischemic stroke in rats, as well as the involvement of SGK1 in these effects. ICSI decreased infarct size and brain swelling, as determined by 2,3,5‑triphenyltetrazolium chloride staining and the dry‑wet weight method, respectively. The results of terminal deoxynucleotidyl transferase mediated nick end labeling (TUNEL) and Nissl staining showed that ICSI also suppressed apoptosis and increased the relative integral optical density (IOD) values of Nissl bodies in the rat MCAO model. Regarding the mechanism, the results of immunohistochemistry and western blotting revealed that ICSI upregulated SGK1 expression and downregulated beclin‑1 and LC‑3 expression in the rat MCAO model. In addition, SGK1 knockdown increased ICSI‑mediated infarct size and brain swelling, promoted apoptosis, and reduced the IOD values of Nissl bodies in the rat MCAO model. In addition, we found that SGK1 knockdown upregulated beclin‑1 and LC‑3 expression mediated by ICSI. Overall, ICSI had a neuroprotective effect on ischemic stroke after reperfusion by upregulating SGK1 and inhibiting autophagy.

Environmentally relevant levels of bisphenol A affect uterine decidualization and embryo implantation through the estrogen receptor/serum and glucocorticoid-regulated kinase 1/epithelial sodium ion channel α-subunit pathway in a mouse model

To investigate whether bisphenol A (BPA) exposure is associated with uterine decidualization and embryo implantation failure in mice. Experimental animal study and invitro study. University-based infertility center. ICR mice. Mice treated with different doses of BPA; Ishikawa cells cultured in medium of different concentrations of BPA. Embryo implantation sites, uterine weight, quantitative real-time reverse transcriptase-polymerase chain reaction, Western blot analysis, hematoxylin and eosin staining, and immunohistochemical, cell proliferation, and statistical analyses. In the experiment of mouse model, administration of 1-100μg/kg/day of BPA by gavage led to reduction of the number of embryo implantation sites in a dose-dependent manner; 100μg/kg/day of BPA statistically significantly reduced the number of implantation sites compared with the control group. The uterine weight change (the wet weight of the decidualized uterine horn divided by the wet weight of the undecidualized uterine horn of the mouse) in groups exposed to BPA (100-10,000μg/kg/day) were statistically significantly lower compared with the control group. Immunohistochemical analysis demonstrated that administration of 100, 1,000, or 10,000μg/kg/day of BPA by gavage statistically significantly down-regulated the expression of epithelial Na+ channel α-subunit (ENaCα) in the luminal epithelial cells and desmin in decidual cells of the oil-induced decidualized uterine horns. Administration of 100μg/kg/day BPA on embryo days 0.5-3.5 by gavage statistically significantly decreased the level of uterine serum and glucocorticoid-regulated kinase 1 (SGK1) protein expression on embryo days 4 and 6. After treatment with 0.001, 0.01, 0.1, or 1.0μg/mL of BPA for 48hours, the SGK1, ENaCα, and phospho-SGK1 protein expression of Ishikawa cells was down-regulated, and the effect of BPA on SGK1 could be abrogated by fulvestrant. Our study provides the first indication that BPA exposure at levels as low as 100μg/kg/day can impair embryo implantation in mice and BPA can affect decidualization of the uterus in mouse model. Our results suggest that BPA can down-regulate SGK1 and ENaCα protein expression through estrogen receptors in Ishikawa cells.

Serum and glucocorticoid-regulated kinase 1 (SGK1) is a predictor of poor prognosis in non-small cell lung cancer, and its dynamic pattern following treatment with SGK1 inhibitor and γ-ray irradiation was elucidated.

The tumor suppressor gene p53 and its dynamic patterns have caused widespread attention in the field of cancer research. Serum and glucocorticoid-regulated kinase1 (SGK1) with features of serine/threonine kinase activity, which also contributes to the structural and functional similarities with the AKT family of kinases, is a key enzyme in the regulation of immune responses in tumor cells, and SGK1 was noted to be expressed in close relation to p53 protein levels, and there exists a negative feedback pathway between intracellular SGK1 and p53. Noteworthy, SGK1 was detected to play a role in the development of resistance to cancer chemotherapy. In this study, we demonstrated that high SGK1 expression had strong prognostic value for reduced overall survival in NSCLC patients. Detection of SGK1 collectively was helpful to predict the prognosis of NSCLC. We also identified the expression level of SGK1 and the p53 pathway including downstream apoptotic proteins under the stimulation of γ-radiation and SGK1 inhibitor GSK650394, which presented a series of dynamic fluctuations. Our results suggest that SGK1 dynamics could play an important role in cell signaling, which is capable of directly influencing NSCLC cellular fate decisions.

Expression of glucocorticoid inducible genes is associated with reductions in cornu ammonis and dentate gyrus volumes in patients with major depressive disorder.

Alterations of the glucocorticoid system and of hippocampal volumes have consistently been reported in patients with major depressive disorders (MDD). The aim of the present study was to investigate whether the messenger RNA (mRNA) expression of glucocorticoid inducible genes is associated with changes in the cornu ammonis (CA) and dentate gyrus subfields. Forty-three patients with MDD and 43 healthy controls were recruited and investigated with high resolution magnetic resonance imaging. Hippocampal subfields were measured using freesurfer. Measurement of whole blood mRNA expression of glucocorticoid inducible genes serum and glucocorticoid-regulated kinase 1 (SGK1), FK506 binding protein 5 (FKBP5), and glucocorticoid induced leucine zipper (GILZ) was performed. Patients with MDD had significantly smaller volumes of CA1, CA2/3, CA4/DG, and subiculum compared to healthy controls. In the regression analysis, the factor diagnosis had a significant moderating effect on the association of SGK1 and hippocampal volumes. Patients with low expression of SGK1 had significantly smaller CA2/3 and CA4/DG volumes compared to patients with high expression of SGK1 mRNA and to healthy controls with low/high expression of SGK1, respectively. Therefore, a lack of mRNA expression of glucocorticoid inducible genes in patients with MDD that seems to correspond to a blunted cortisol response is associated with smaller hippocampal CA and dentate gyrus volumes. SGK1 seems to be particularly relevant for stress-related mental disorders.

Activity of ROMK Channel is Regulated by PPARγ in the Xenopus Oocytes

Thiazolidinediones (TZDs) are antidiabetics drugs (agonists of the nuclear receptor PPARγ) used during the last ten years for the treatment of type II diabetes. Unfortunately, their use can induce fluid retention and is also associated with the formation of kidney oedema. Recent studies have suggested the implication of the epithelial sodium channel expressed in the renal collecting duct for these adverse side effects. Indeed, the PPARγ stimulation by TZDs activate epithelial sodium channel probably by inducing the expression and the activation of SGK1 (Serum and Glucocorticoid-regulated Kinase 1). It is well known that the sodium and potassium transport are tightly linked at the kidney level. Our objective is to determine if the TZD rosiglitazone (RGZ) is directly implicated into the regulation of the potassium transpport. To do so, we performed two electrode voltage clamp studies (TEVC) in Xenopus laevis oocytes expressing PPARγ receptor, wild type (wt) and mutant ROMK channels. We have shown that a 48h treatment with 10 μM RGZ produced a 2-fold increase of wt ROMK activity. This activation is blocked by GW9662, a PPARγ antagonist. We have also shown the implication of SGK1 into the regulation of ROMK channels by using an inhibitor of SGK1, SGK650394 and by mutating the phosphorylation site of SGK1 on ROMK (ROMK-S44A). Finally, immunofluorescence experiments have shown the recruitment of ROMK at the cell's membrane of the oocytes treated with RGZ. All the results suggest that RGZ increase the potassium current generated by ROMK by increasing the expression of SGK1 and promoting the recruitment of ROMK to the cell's membrane.

Serum- and Glucocorticoid-induced Protein Kinase 1 (SGK1) Is Regulated by Store-operated Ca2+ Entry and Mediates Cytoprotection against Necrotic Cell Death

Serum and glucocorticoid-regulated kinase 1 (SGK1) encodes a phosphatidylinositol 3-kinase-dependent serine/threonine kinase that is rapidly induced in response to cellular stressors and is an important cell survival signal. Previous studies have suggested that an increase in cytoplasmic Ca(2+) concentration ([Ca(2+)]c) is required for increased SGK1 expression, but the subcellular source of Ca(2+) regulating SGK1 transcription remains uncertain. Activation of endoplasmic reticulum stress (ERS) with thapsigargin (TG) increased SGK1 mRNA and protein expression in MDA-MB-231 cells. Intracellular Ca(2+) imaging revealed that store-operated Ca(2+) entry played a prominent role in SGK1 induction by TG. Neither ERS nor release of Ca(2+) from the ER was sufficient to activate SGK1. Prolonged elevation of intracellular Ca(2+) levels, however, triggered cell death with a much greater proportion of the cells undergoing necrosis rather than apoptosis. A relative increase in the percentage of cells undergoing necrosis was observed in cells expressing a short hairpin RNA targeted to the SGK1 gene. Necrotic cell death evoked by cytoplasmic Ca(2+) overloading was associated with persistent hyperpolarization of the inner mitochondrial membrane and a modest increase in calpain activation, but did not involve detectable caspase 3 or caspase 7 activation. The effects of cytoplasmic Ca(2+) overloading on mitochondrial membrane potential were significantly reduced in cells expressing SGK1 compared with SGK1-depleted cells. Our findings indicate that store-operated Ca(2+) entry regulates SGK1 expression in epithelial cells and suggest that SGK1-dependent cytoprotective signaling involves effects on maintaining mitochondrial function.

Papel de la quinasa regulada por suero y glucocorticoides 1 en las alteraciones cardiacas producidas por la aldosterona en ratas

IntroductionAldosterone induces cardiac hypertrophy and it is known to induce serum and glucocorticoid regulated kinase 1 (SGK-1) gene expression. AimWe aimed to evaluate structural, functional, inflammatory and oxidative alterations, as well as serum and glucocorticoid regulated kinase1 (SGK-1) expression, produced in rat heart by aldosterone+salt administration. Treatment with spironolactone was evaluated to prove mineralocorticoids mediation. Matherial and methodsMale Wistar rats received aldosterone (1mg/kg/day)+1% NaCl for 3 weeks. Half of the animals were treated with spironolactone (200mg/kg/day). At the end of treatment hemodynamics were measured: SBP, DBP, LVEDP, LVSP, +dP/dt and –dP/dt. Heart relative weight was measured as cardiac hypertrophy index. mRNA expression of TGF-β, CTGF, MMP2, TIMP2, TNF-α,IL-1β, p22phox, eNOS and SGK-1 were measured. Cardiac collagen content was measured by histological techniques. ResultsSBP and DBP, LVSP and LVEDP were elevated (P<.05) in aldosterone+salt-treated rats. –dP/dt decreased (P<.05) in aldosterone+salt-treated rats, but +dP/dt was similar in all groups. Spironolactone normalized (P<.05) SBP, DBP, LVSP, LVEDP and –dP/dt. Relative heart weight, collagen content, mRNA expression of TGF-β, CTGF, MMP2, TIMP2, TNF-α, IL-1β, p22phox, eNOS and SGK-1 were increased (P<.05) in aldosterone+salt-treated rats, being reduced by spironolactone (P<.05). ConlusionsSGK-1 might be a key mediator in the structural, functional and molecular cardiac alterations induced by aldosterone+salt in rats. All the observed changes and mediators are related with activation of mineralocorticoid receptors.

Opposite effects of serum- and glucocorticoid-regulated kinase-1 and glucocorticoids on POMC transcription and ACTH release

Serum- and glucocorticoid-regulated kinase-1 (SGK1) is a glucocorticoid early-response gene; its function, however, has been elucidated mainly in the context of mineralocorticoid signaling. Here, we investigate the expression and function of SGK1 in the pituitary gland, one of the primary glucocorticoid targets. SGK1 is expressed in the human pituitary gland and colocalizes to ACTH. The AtT-20 murine corticotroph cell line was used for functional experiments. Glucocorticoids upregulated SGK1 mRNA and protein levels, parallel to decreasing proopiomelanocortin (POMC) transcription and ACTH release. Dexamethasone-induced changes in SGK1 protein were abolished by the steroid receptor antagonist RU-486 and reduced by the inhibition of PI 3-kinase with LY-294002. SGK1 overexpression increased CREB- and activator protein-1-dependent transcription, POMC transcription, and ACTH secretion but did not influence intracellular cAMP levels. SGK1 overexpression and corticotropin-releasing hormone had additive effects on POMC promoter activity but not on ACTH secretion. SGK1 knockdown by RNA interference decreased POMC promoter activity, demonstrating the importance of SGK1 for basal POMC signaling. In summary, SGK1 is strongly stimulated by glucocorticoids in pituitary corticotrophs; however, its effects on POMC transcription are antagonistic to the classical inhibitory glucocorticoid action, suggesting a cell-regulated counterregulatory mechanism to potentially detrimental glucocorticoid effects.

Gender Differences in Serum and Glucocorticoid Regulated Kinase-1 (SGK-1) Expression during Renal Ischemia/Reperfusion Injury

Several studies reported sexual dimorphism in the signaling mechanisms of renal ischemia/reperfusion (I/R). The anti-apoptotic serum and glucocorticoid-regulated kinase-1 (SGK-1) is up-regulated and has a significant protective role in renal I/R. SGK-1 has several target molecules, and inhibition of the inducible nitric oxide synthase (iNOS) transcription is one of its effector mechanisms. The objective of the present study was to examine if there is a gender-specific expression and activation of SGK-1 during renal I/R injury. In vitro, treatment of HK-2 kidney proximal tubular cells with different concentrations of 17-beta estradiol had no effect, whereas testosterone increased SGK-1 abundance in a dose-dependent manner. In vivo, in a rat model of unilateral renal I/R injury, there was a higher SGK-1 expression and phosphorylation in males 2 and 24 h after ischemia paralleled by reduction in the mRNA expression of iNOS compared to females. Deprivation of testosterone by castration of males resulted in decreased SGK-1 protein level at all time-points and reduced phosphorylation 2 and 24 h after reperfusion. Our results suggest that testosterone up-regulates SGK-1 in the kidney contributing to sexual dimorphisms in the cell signalling machinery. The significance of the testosterone-regulated SGK-1 level and activity in the kidney needs further investigations.

Increased Expression of Serum‐ and Glucocorticoid‐regulated Kinase‐1 in the Duodenal Mucosa of Children With Coeliac Disease

Enterocyte apoptosis induced by activated intraepithelial lymphocytes is increased in coeliac disease (CD). Serum- and glucocorticoid-regulated kinase-1 (SGK1) is a serine/threonine protein kinase that may inhibit apoptosis and compensate for the excessive death of surface epithelial cells. The significance of SGK1 in CD is elusive so far. The aim of this study was to characterise the expression and localisation of SGK1 in duodenal biopsy samples taken from children with untreated CD, children with treated CD, and controls. Duodenal biopsy specimens were collected from 16 children with untreated CD, 9 children with treated CD, and 10 controls. The mRNA expression of SGK1 was determined by real-time reverse transcription-polymerase chain reaction. SGK1 and phosphorylated (P)-SGK1 protein levels and their localisation were determined by Western blot and immunofluorescent staining, respectively. We found increased SGK1-mRNA expression as well as higher SGK1 and P-SGK1 protein levels in the duodenal mucosa of children with untreated CD compared with controls. In the duodenal mucosa of children with treated CD, SGK1-mRNA expression was decreased and SGK1 and P-SGK1 protein levels were lower than in untreated CD. SGK1 and P-SGK1 staining intensity was stronger in duodenal villous enterocytes of children with untreated CD compared with treated CD. Our results of increased expression of SGK1 in untreated CD may suggest its contribution to the enterocyte survival in this disease.

Role of serum and glucocorticoid-regulated kinase-1 in the protective effects of erythropoietin during renal ischemia/reperfusion injury

Erythropoietin (EPO) protects the kidneys from ischemia/reperfusion (I/R) injury; however, the exact signalling mechanisms are not fully understood. The serum and glucocorticoid-regulated kinase 1 (SGK1) is an anti-apoptotic protein kinase regulated through the phosphatidylinositol 3-kinase (PI3-kinase) pathway by cellular stimuli, hormones and growth factors. The objective of the present study was to examine the role of SGK1 in the renoprotective effects of EPO in renal I/R injury. In vitro, cultures of HEK293 cells were exposed to 16 h hypoxia. Incubation with EPO at a doses of 400 U/ml exerted a protective effect on cell death assessed by LDH release and Annexin V FACS analysis. This was paralleled by up-regulation of SGK1 expression, as well as phosphorylation. Downregulation of SGK1 expression by small interfering RNA technique ameliorated the anti-apoptotic effect of EPO treatment. In an in vivo rat model of unilateral renal I/R injury, rats were treated with 500 U/kg EPO 24 h prior to ischemia. EPO resulted in less severe tissue injury and ameliorated the elevation in creatinine and urea nitrogen levels 24 h after reperfusion. Furthermore, SGK1 expression and phosphorylation were higher in EPO compared to vehicle-treated rats as demonstrated by real-time PCR, Western blot and immunofluorescence technique. We conclude that EPO protects from renal I/R injury and SGK1 might contribute to the mediation of EPO effects under ischemic conditions.

Adaptive Variation Regulates the Expression of the Human SGK1 Gene in Response to Stress

The Serum and Glucocorticoid-regulated Kinase1 (SGK1) gene is a target of the glucocorticoid receptor (GR) and is central to the stress response in many human tissues. Because environmental stress varies across habitats, we hypothesized that natural selection shaped the geographic distribution of genetic variants regulating the level of SGK1 expression following GR activation. By combining population genetics and molecular biology methods, we identified a variant (rs9493857) with marked allele frequency differences between populations of African and European ancestry and with a strong correlation between allele frequency and latitude in worldwide population samples. This SNP is located in a GR-binding region upstream of SGK1 that was identified using a GR ChIP-chip. SNP rs9493857 also lies within a predicted binding site for Oct1, a transcription factor known to cooperate with the GR in the transactivation of target genes. Using ChIP assays, we show that both GR and Oct1 bind to this region and that the ancestral allele at rs9493857 binds the GR-Oct1 complex more efficiently than the derived allele. Finally, using a reporter gene assay, we demonstrate that the ancestral allele is associated with increased glucocorticoid-dependent gene expression when compared to the derived allele. Our results suggest a novel paradigm in which hormonal responsiveness is modulated by sequence variation in the regulatory regions of nuclear receptor target genes. Identifying such functional variants may shed light on the mechanisms underlying inter-individual variation in response to environmental stressors and to hormonal therapy, as well as in the susceptibility to hormone-dependent diseases.