Serum And Glucocorticoid-inducible Kinase 1 Research Articles

Deletion of SGK1 in Smooth Muscle Cells Induces Sex-specific Differences in Obesity-mediated Metabolic Dysfunction and Adipose Tissue Remodeling

Objectives: Obesity, characterized by an excess of adipose tissue, is an important risk factor for the development of metabolic diseases such as type 2 diabetes. In obesity, poor metabolic health is partly due to glucose intolerance, a condition in which whole-body glucose regulation is impaired. Adipose tissue is an endocrine organ central for optimal metabolic health and its expansion by excessive fat intake induces metabolic dysfunction. The molecular mechanisms that promote metabolic dysfunction in obesity are not fully understood. Adipose tissue function is dependent on the presence of new vascular networks capable of supplying nutrients and oxygen during adipose tissue expansion. Thus, pathological vascular remodeling may promote adipose tissue expansion and dysfunction in obesity. In this regard, our previous studies have shown that serum and glucocorticoid-inducible kinase 1 (SGK1) in vascular smooth muscle cells (vSMCs) mediates pathological vascular remodeling in obesity. SGK1 is a serine/threonine kinase that becomes elevated in the vasculature during obesity and is implicated in the development of metabolic syndrome. Therefore, we hypothesize that smooth muscle cell derived-SGK1 promotes pathological adipose tissue remodeling and metabolic dysfunction during obesity by perturbing adipose tissue vascularization. Methods: To test this hypothesis, these studies utilized our novel SMC-specific SGK1 knockout (smSGK1KO) mouse model to study the influence of SMC-derived SGK1 on adipose tissue remodeling and overall metabolic health in vivo. Male and female 8-week-old smSGK1WT and smSGK1KO mice were subjected to either a 10% low-fat diet (LF) or a high-fat diet (HF) for 8 weeks with weekly body weight measurements. Upon completion of respective diets, mice were subjected to glucose tolerance tests (GTT) to assess glucose tolerance and metabolic health. Adipose tissues from the subcutaneous (inguinal) and intra-abdominal (epididymal/gonadal) white adipose tissue (WAT) depots were harvested to assess overall adiposity and vascularization. Results: Our data show sexual dimorphism exists in the way smSGK1KO mice respond to a chronic high-fat diet. When fed a HF diet, female smSGK1KO mice gained approximately 60% more weight than their female smSGK1WT counterparts. In contrast, weight gain was about 50% lower in male smSGK1KO compared to male smSGK1WT mice on the same HF diet. Despite the differences in weight gain, inguinal and epididymal/gonadal WAT were reduced in male and female smSGK1KO mice fed a HF diet. Surprisingly, GTT was similar between female smSGK1KO and smSGK1WT mice, despite the increased weight gain, while male smSGK1KO mice displayed improvement in glucose tolerance in comparison to their wildtype counterparts. Moreover, male smSGK1KO mice appear to have enhanced vascularization in WAT depots as evidenced by increased vascular branching in fat pads. Conclusions: These studies suggest that SGK1 in smooth muscle cells contributes to adipose tissue remodeling and metabolic dysfunction under obesogenic conditions. Additionally, these studies indicate a need to understand the mechanisms by which crosstalk between the vasculature and adipose tissue modulates obesity and overall metabolic health. This research is supported in part by grant number 5U24DK132733-02 from the National Institute of Health, NIH. This research is supported in part by grant number 5T32HL007609-36 from the National Institute of Health, NIH. This research is supported in part by grant number 2100832 from the National Science Foundation, NSF. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The protective effects of gallic acid and SGK1 inhibitor on cardiac damage and genes involved in Ca2+ homeostasis in an isolated heart model of ischemia/reperfusion injury in rat.

Serum and glucocorticoid-induced kinase 1 (SGK1) is an enzyme that may play a vital role in myocardial ischemia/reperfusion (I/R) injury. This enzyme may affect sarcoplasmic reticulum Ca2+ ATPase (SERCA2), ryanodine receptor (RyR2) and sodium/calcium exchanger (NCX1) during myocardial ischemia/reperfusion injury. The objective of this investigation was to analyze theeffects ofthe combination of GSK650394 (SGK1 inhibitor) and gallic acid on the calcium ions regulation, inflammation, and cardiac dysfunction resulting from ischemia/reperfusion (I/R) injury in the heart. Sixty male Wistar rats were randomly divided into six groups, pretreated with gallic acid or vehicle for 10 days. Then the heart was isolated and exposed to I/R. In the SGK1 inhibitor groups, GSK650394 was infused 5 min before ischemia induction. After that, Ca2+ homeostasis, inflammatory factors, cardiac function, antioxidant activity, and myocardial damage were evaluated. The findings suggested that the use of two drugs in combination therapy produced more significant improvements in left ventricular end diastolic pressure, left ventricular systolic pressure, RR-interval, ST-elevation, inflammation factors, and antioxidant enzymes activity as compared to the use of each drug. Despite this, there was a significant decrease observed in heart marker enzymes (including lactate dehydrogenase (LDH), troponin-I (cTn-I), creatine kinase-MB (CK-MB) and creatine phosphokinase (CPK) when compared to the ischemic group. Additionally, the expression of RyR2, NCX1, and SERCA2 genes showed a noteworthy increase as compared to the ischemic group. The findings of this study propose that using both of these agents on myocardial I/R injury could have superior advantages compared to using only one of them.

SGK1 aggravates idiopathic pulmonary fibrosis by triggering H3k27ac-mediated macrophage reprogramming and disturbing immune homeostasis.

Idiopathic pulmonary fibrosis (IPF) is characterized by fibrotic matrix deposition and irreversible aberrant tissue remodeling. Their mechanisms of action are associated with the activation of macrophages and a disturbed immune environment. We aim to determine how these activated macrophages influenced the pathogenesis of pulmonary fibrosis. We found the fibrotic areas of IPF patients contained more serum and glucocorticoid-induced kinase 1 (SGK1)-positive and M2-type macrophages. Similarly, bleomycin (BLM)+LPS significantly triggered high expression of SGK1 in the IPF mice, accompanied by destroyed lung structure and function, increased fibrosis markers and disturbed immune microenvironment. Mechanistically, SGK1 markedly promoted the reprogramming of M2-type macrophages in fibrotic lungs by triggering glycogen synthase kinase 3beta (GSK3β)-tat-interacting protein 60 (TIP60)- histone-3 lysine-27 acetylation (H3K27ac) signalings, which further released chemokine (C-C motif) ligand 9 (CCL9) to attract Th17 cells and delivered TGF-β to fibroblasts for synergistically destroying immune microenvironment, which was largely reversed by macrophage depletion in mice. We took macrophages as the entry point to deeply analyze IPF pathogenesis and further provided insights for the development of novel drugs represented by SGK1.

Suppression of circular RNA serum and glucocorticoid-induced kinase 1 elevates antioxidant molecules and angiogenesis in trophoblast cells to attenuate preeclampsia via microRNA-508-3p to target and restrain PUM homolog 1.

Preeclampsia (PE) is a pregnancy-specific syndrome characterized by hypertension and proteinuria. Recently, multiple circular RNAs (circRNAs) were considered latent clinical diagnostic markers or therapeutic targets. This study was to explore the impact of circRNA serum and glucocorticoid-induced kinase 1 (SGK1) on PE via influencing the microRNA (miR)-508-3p/PUM homolog 1 (PUM1) axis. Placental tissues of 34 pregnant women with PE and 34 normal pregnant women were collected to measure circRNA SGK1 (circSGK1), miR-508-3p, and PUM1. Human placental trophoblasts HTR-8/SVneo were transfected with plasmids, thereafter to observe proliferation, migration, invasion, and apoptosis, analyze antioxidant molecules Troxerutin (TXN), Glutamate-cysteine ligase catalytic subunit (GCLC), NAD (P) H-quinone oxidoreductase 1 (NQO1), and determine angiogenesis. After the construction of the PE rat model, antioxidant molecules TXN, GCLC, and NQO1, vascular-associated factor vascular endothelial growth factor A (VEGF-A), and histopathological conditions were tested. Examination of the binding of circSGK1 and miR-508-3p with PUM1 was performed. Our data showed that circSGK1 expression was elevated in the placenta of patients with PE. Silenced circSGK1 or elevated miR-508-3p promoted the growth and antioxidant molecules and angiogenesis in trophoblast cells; CircSGK1 combined with miR-508-3p, and miR-508-3p targeted PUM1. In summary, suppression of circSGK1 augments antioxidant molecules and angiogenesis in trophoblast cells to attenuate PE via miR-508-3p to target PUM1.

Abstract 18373: Differential Effects of Hypertension and Aneurysm on Stiffness Properties of the Abdominal Aorta

Introduction: The serum and glucocorticoid inducible kinase-1 (SGK-1) can contribute to matrix remodeling in murine models of hypertension (HTN) and abdominal aortic aneurysm (AAA), a potential biomechanical link between these aortopathies. Utilizing aortic stiffness as a marker of pathologic remodeling. Hypothesis: We hypothesize that HTN causes an SGK-1 dependent increase in aortic stiffness to amplify AAA growth. Methods: AngiotensinII (AngII) infusion induced HTN in C57Bl/6 mice (WT;1.46mg/kg/day) with subset groups treated + periadventitial CaCl2 to induce AAA and + infusion of the specific SGK-1 inhibitor EMD638683 (2.5mg/kg/day;n=2-4 each). Abdominal aortic ultrasound was conducted on Day 0 and Day 21 to measure stiffness parameters (radial strain(RS), distensibility(D), pulse propagation velocity(PPV)). Aortic diameter (AoD) was obtained by ultrasound and systolic blood pressures (SBP) were measured by Coda tail cuff. Results: This HTN model has consistently resulted in >30% increase in SBP and AAA induction did not effect SBP. Although the WT+AngII+AAA mice had 66+8% increase in AoD, dilation was not amplified beyond that of the WT+AAA mice (72+7%, p=NS). Treatment with EMD had no impact on SBP, but did significantly reduce AAA growth (WT+AAA+EMD=29+5%; WT+AngII+AAA+EMD= 24+3%), therefore despite ongoing mechanical tension, SGK-1 inhibition abrogated a pathway necessary for degenerative remodeling. Accordingly, aortic stiffness was differentially altered in HTN versus AAA. As indictors of increased stiffness, D decreased with HTN (p<0.05 vs Day 0) and RS decreased with AAA (p<0.05 vs Day 0), but SGK-1 inhibition had no effect, indicating that the matrix remodeling driving these mechanical parameters was not SGK-1 dependent. Conversely, PPV was increased in both aortopathies (WT+AAA, WT+AngII, WT+AngII+AAA; each p<0.05 vs Day 0) but EMD infusion prevented elevation in PPV, suggesting SGK-1-dependent preservation of contractility. Conclusions: Although concurrent induction of HTN and AAA did not amplify AAA growth, these aortopathies differentially impacted aortic stiffness. Tracking PPV as an indicator of pathologic SGK-1 activity may represent a pharmacological target to abrogate dysfunctional aortic remodeling.

Inhibition of SGK1 potentiates the anticancer activity of PI3K inhibitor in NSCLC cells through modulation of mTORC1, p‑ERK and β‑catenin signaling.

Non-small cell lung cancer (NSCLC) is one of the deadliest types of cancer with poor prognosis, accounting for 85% of all lung cancer cases. The phosphoinositide 3-kinase (PI3K) signaling pathway is most frequently altered in NSCLC; nonetheless, targeting this pathway yields limited success primarily because of drug-induced resistance. PI3K-independent activation of serum and glucocorticoid-induced kinase 1 (SGK1) is responsible for development of resistance to PI3K/AKT inhibitors in breast cancer. The present study investigated potential of inhibiting SGK1 activity for the potentiation of PI3K inhibitor activity in NSCLC cell lines using in vitro anti-proliferation assays, protein expression profiling using western blotting and cell cycle analysis. The findings revealed that combined inhibition of PI3K/AKT and SGK1 resulted in synergistic anticancer activity, with increased apoptosis, DNA damage and cell cycle arrest in G1 phase. Furthermore, high SGK1 protein expression in NSCLC cell lines was associated with increased resistance to PI3K inhibitors. Therefore, enhanced SGK1 expression may serve as a marker to predict therapeutic response to PI3K/AKT inhibitors. Profiling of downstream signaling proteins demonstrated that, at the molecular level SGK1-mediated sensitization of NSCLC cell lines to PI3K inhibitors was achieved via inhibition of mTORC1 signaling. Increased sensitivity of NSCLC cell lines was also mediated by other oncogenic pathways, such as Ras/MEK/ERK and Wnt/β-catenin signaling.

Abstract P3016: Pathologic Matrix Markers Are Differentially Modulated By VSMC-Specific SGK-1 Activity In Hypertension And Abdominal Aortic Aneurysm

Introduction: The VSMC switch to synthetic phenotype promotes aortic pathology such as hypertension (HTN) and abdominal aortic aneurysm (AAA). Mechanical activation of serum and glucocorticoid inducible kinase-1 (SGK-1) alters the VSMC synthetic profile to promote remodeling. Plasma biomarkers may represent opportunities to assess VSMC function in aortic disease, and we hypothesize that analysis of a panel of plasma pathologic matrix markers (PMM) representing synthetic VSMC phenotype can reflect SGK-1-dependent activity. Methods: HTN was induced in wild-type C57Bl/6 (WT) and smooth muscle cell specific SGK-1 knockout (SMC-SGK-1KO +/- ) mice with AngiotensinII infusion (1.46mg/kg/day, n=4-6). Separate mice underwent AAA induction by peri-adventitial CaCl 2 application (n=4-6). Terminal procedure included collecting systolic blood pressure (SBP), aortic diameter (AoD), and plasma. ELISA for PMMs included Interleukin-6 (IL-6), Matrix Metalloproteinase-9 (MMP-9), Cathepsin S (CtsS), and Cystatin C (CysC), Osteoprotegerin (OPG), and Tenascin C (TNC). Impact of the panel was evaluated by a composite T-score. Statistics included T-test and ANOVA. Results: WT+HTN had >30% increased SBP and elevation of IL-6, CtsS, CysC, and TNC (p<0.05). SMC-SGK-1KO +/- +HTN had equally elevated SBP, but no change in PMMs, suggesting that SGK-1 contributed to HTN-induced VSMC synthetic activity. WT+AAA had >65% increased AoD and elevation of all PMMs (p<0.05). Alternatively, SMC-SGK-1KO +/- +AAA had abrogated growth (29.4 + 3.6%, p<0.05 vs WT and WT+AAA) with IL-6, CtsS, CysC, and TNC returning to baseline, suggesting that SGK-1-dependent production of these PMMS was necessary for true AAA growth. Composite T-scores differed between Control, HTN, and AAA in WT mice (0.78 + 0.08 vs 2.91 + 0.29 vs 7.11 + 0.71 respectively, p<0.05). In SMC-SGK-1KO +/- mice, T-score normalized in HTN but remained elevated in AAA (2.19 + 0.21, p<0.05 vs Control and WT+AAA), attributable to the elevations in MMP-9 and OPG, peptides produced by inflammatory infiltrate. Conclusion: A panel of PMMs can be scored to reflect synthetic activity of VSMCs in aortic pathology, as well as response to inhibition, and warrants further investigation for the clinical care of patients with vascular disease.

Histone methyltransferase KMT2D inhibits ENKTL carcinogenesis by epigenetically activating SGK1 and SOCS1.

Epigenetic alteration plays an essential role in the occurrence and development of extranodal natural killer/T cell lymphoma (ENKTL). Histone methyltransferase (HMT) KMT2D is an epigenetic regulator that plays different roles in different tumors, but its role and mechanism in ENKTL are still unclear. We performed immunohistochemical staining of 112 ENKTL formalin-fixed paraffin-embedded (FFPE) samples. Then, we constructed KMT2D knockdown cell lines and conducted research on cell biological behavior. Finally, to further investigate KMT2D-mediated downstream genes, ChIP-seq and ChIP -qPCR was performed. The low expression of KMT2D was related to a decreased abundance in histone H3 lysine 4 mono- and trimethylation (H3K4me1/3). In KMT2D knockdown YT and NK-YS cells, cell proliferation was faster (P < 0.05), apoptosis was decreased (P < 0.05), the abundance of S phase cells was increased (P < 0.05), and the level of H3K4me1 was decreased. Notably, ChIP-seq revealed two crucial genes and pathways downregulated by KMT2D. KMT2D is a tumor suppressor gene that mediates H3K4me1 and influences ENKTL proliferation and apoptosis by regulating the cell cycle. Moreover, in ENKTL, serum- and glucocorticoid-inducible kinase-1 (SGK1) and suppressor of cytokine signaling-1 (SOCS1) are downstream genes of KMT2D.

The role of the SGK3/TOPK signaling pathway in the transition from acute kidney injury to chronic kidney disease.

Introduction: Profibrotic phenotype of renal tubular epithelial cells (TECs) featured with epithelial to mesenchymal transition (EMT) and profibrotic factors secretion, and aberrant accumulation of CD206+ M2 macrophages are the key points in the transition from acute kidney injury (AKI) to chronic kidney disease (CKD). Nevertheless, the underlying mechanisms involved remain incompletely understood. Serum and glucocorticoid-inducible kinase (SGK) is a serine/threonine protein kinase, required for intestinal nutrient transport and ion channels modulation. T-LAK-cell-originated protein kinase (TOPK) is a member of the mitogen activated protein kinase family, linked to cell cycle regulation. However, little is known about their roles in AKI-CKD transition. Methods: In this study, three models were constructed in C57BL/6 mice: low dose and multiple intraperitoneal injection of cisplatin, 5/6 nephrectomy and unilateral ureteral obstruction model. Rat renal tubular epithelial cells (NRK-52E) were dealt with cisplatin to induce profibrotic phenotype, while a mouse monocytic cell line (RAW264.7) were cultured with cisplatin or TGF-β1 to induce M1 or M2 macrophage polarization respectively. And co-cultured NRK-52E and RAW264.7 through transwell plate to explore the interaction between them. The expression of SGK3 and TOPK phosphorylation were detected by immunohistochemistry, immunofluorescence and western blot analysis. Results: In vivo, the expression of SGK3 and p-TOPK were gradually inhibited in TECs, but enhanced in CD206+ M2 macrophages. In vitro, SGK3 inhibition aggravated epithelial to mesenchymal transition through reducing the phosphorylation state of TOPK, and controlling TGF-β1 synthesis and secretion in TECs. However, SGK3/TOPK axis activation promoted CD206+ M2 macrophage polarization, which caused kidney fibrosis by mediating macrophage to myofibroblast transition (MMT). When co-cultured, the TGF-β1 from profibrotic TECs evoked CD206+ M2 macrophage polarization and MMT, which could be attenuated by SGK3/TOPK axis inhibition in macrophages. Conversely, SGK3/TOPK signaling pathway activation in TECs could reverse CD206+ M2 macrophages aggravated EMT. Discussion: We revealed for the first time that SGK3 regulated TOPK phosphorylation to mediate TECs profibrotic phenotype, macrophage plasticity and the crosstalk between TECs and macrophages during AKI-CKD transition. Our results demonstrated the inverse effect of SGK3/TOPK signaling pathway in profibrotic TECs and CD206+ M2 macrophages polarization during the AKI-CKD transition.

Induction of SGK1 via glucocorticoid-influenced clinical outcome of triple-negative breast cancer patients.

Triple-negative breast cancer (TNBC) is a highly heterogeneous and aggressive breast malignancy. Glucocorticoid (GC)-glucocorticoid receptor (GR) pathway plays a pivotal role in the cellular responses to various stresses including chemotherapy. Serum- and glucocorticoid-induced kinase-1 (SGK1) is known as an important downstream effector molecule in the GR signaling pathway, we attempted to explore its clinicopathological and functional significance in TNBC in which GR is expressed. We first immunolocalized GR and SGK1 and correlated the results with clinicopathological variables and clinical outcome in 131 TNBC patients. We also evaluated the effects of SGK1 on the cell proliferation and migration in TNBC cell lines with administration of dexamethasone (DEX) to further clarify the significance of SGK1. The status of SGK1 in carcinoma cells was significantly associated with adverse clinical outcome in TNBC patients examined and was significantly associated with lymph node metastasis, pathological stage, and lymphatic invasion of the patients. In particular, SGK1 immunoreactivity was significantly associated with an increased risk of recurrence in GR-positive TNBC patients. Subsequent in vitro studies also demonstrated that DEX promoted TNBC cell migration and the silencing of gene expression did inhibit the cell proliferation and migration of TNBC cells under DEX treatment. To the best of our knowledge, this is the first study to explore an association between SGK1 and clinicopathological variables and clinical outcome of TNBC patients. SGK1 status was significantly positively correlated with adverse clinical outcome of TNBC patients and promoted carcinoma cell proliferation and migration of carcinoma cells.

Effect of Gallic Acid Pretreatment and SGK1 Enzyme Inhibition on Cardiac Function and Inflammation in a Rat Model of Ischemia-Reperfusion Injury.

Serum and glucocorticoid-induced kinase 1 (SGK1) is an enzyme that may play an important role in ischemic-reperfusion (I/R) injury and myocardial dysfunction. Although many studies have been conducted on individual antioxidants, little attention has been paid to the effects of co-administration of an antioxidant with an SGK1 inhibitor on cardiac function after I/R. This study aimed to determine the effects of gallic acid (as an antioxidant) combined with an SGK1 inhibitor on I/R-induced cardiac dysfunction and inflammation. Sixty male Wistar rats were randomized into 6 groups, pretreated with gallic acid or vehicle for 10 days. Subsequently, the heart was isolated and exposed to I/R. In groups that received the SGK1 inhibitor, the heart was perfused with the SGK1 inhibitor GSK650394, 5 min before induction of ischemia. After that, cardiac function, inflammatory factors, and myocardial damage were evaluated. The combination of these two compounds improved cardiac contractility, heart rate, rate pressure product, left ventricular developed pressure, left ventricular systolic pressure, perfusion pressure, and QRS voltage significantly (P < 0.05). In addition, concomitant therapy of these two agents reduced tumor necrosis factor-alpha and interleukin-6, and the activity of creatine kinase-MB, lactate dehydrogenase, and troponin-I (P < 0.05). The results indicated that administration of gallic acid with the SGK1 inhibitor may have a potentiating effect on the improvement of cardiac dysfunction and I/R-induced inflammation.

Upregulated TNF-α and lactate following ERK-SGK1 activation in the spinal dorsal horn underlies chronic postsurgical pain.

Skin/muscle incision and retraction (SMIR) during surgeries can lead to chronic postsurgical pain (CPSP). The underlying mechanisms are still unclear. In the present study, we showed that SMIR of the thigh induced phosphorylation of extracellular signal-regulated kinase (ERK), followed by serum- and glucocorticoid-inducible kinase-1 (SGK1) activation in the spinal dorsal horn. Intrathecal injection of PD98059, an ERK inhibitor, or GSK650394, a SGK1 inhibitor, significantly attenuated mechanical pain hypersensitivity in SMIR rats. The level of tumor necrosis factor α and lactate in spinal cord was significantly decreased by PD98059 or GSK650394 injection. Furthermore, PD98059 decreased the activation of SGK1 in the spinal dorsal horn. These results indicate that ERK-SGK1 activation followed by proinflammatory mediator release in the spinal dorsal horn underlies CPSP.

Low-dose dexamethasone promotes osteoblast viability by activating autophagy via the SGK1/FOXO3a signaling pathway.

Autophagy contributes to bone homeostasis and development under physiological conditions. Although previous studies have demonstrated the induction of the autophagy machinery by endogenous glucocorticoids (GCs), the precise mechanisms involved have not yet been clarified. The current study aimed to explore the effect of a low dose of GC (10-8 M dexamethasone, Dex) on autophagy in mouse embryonic osteoblastic precursor cells (MC3T3-E1 cells) and the potential mechanisms. The results showed that 10-8 M Dex induced significant time-dependent increases in the expression and activation of serum- and glucocorticoid-induced kinase-1 (SGK1) in MC3T3-E1 cells and that these effects were accompanied by increased cell viability and decreased apoptosis. The autophagy inhibitor 3-MA significantly inhibited Dex-mediated promotion of viability. Moreover, Dex increased LC3II and Beclin-1 levels and decreased SQSTM/p62 levels in a time-dependent manner, and these effects were attenuated by pretreatment with 3-MA. Transfection of Dex-treated MC3T3-E1 cells with shRNA-SGK1 resulted in a significant reduction in cell viability and an increase in apoptosis. 3-MA further exacerbated these effects of SGK1 inhibition. Knocking down SGK1 before Dex exposure significantly reduced the phosphorylated forkhead box O3a (p-FOXO3a)/FOXO3 ratio, suppressed LC3II and Beclin-1 levels, and increased SQSTM/p62 levels in MC3T3-E1 cells, and these effects were amplified by 3-MA. In conclusion, the results revealed that low-dose GC treatment increased osteoblast viability by activating autophagy via the SGK1/FOXO3a pathway.

Abstract P3038: Upregulation Of The Mitochondrial Calcium Uniporter Abolishes Mitochondrial Dysfunction Associated With Obesity In Vascular Smooth Muscle Cells

Obesity is a growing national epidemic that is associated with an increased prevalence of arterial disease. We found that aortic medial hypertrophy during obesity was accompanied by upregulation of serum and glucocorticoid-inducible kinase 1 (SGK1) and reduced mitochondrial oxidative capacity of vascular smooth muscle cells (VSMC). Interestingly, VSMC-specific deletion of SGK1 attenuated obesity-related aortic remodeling and restored mitochondrial oxidative capacity in VSMC implicating a mediator role for SGK1 in mitochondrial dysfunction during obesity. The mechanistic basis for impaired mitochondrial respiration during obesity in VSMC is unknown. Thus, due to its fundamental role in stimulation of mitochondrial oxidative phosphorylation, the current study will investigate the mitochondrial calcium uniporter (MCU) in obesity-related mitochondrial dysfunction in VSMC. As SGK1 is known to regulate the expression and/or activity of ion channels, we hypothesize that upregulation of SGK1 during obesity negatively regulates MCU expression, mitochondrial oxidative activity, and ATP production. MCU protein levels were assessed by western blot analysis. Mitochondrial oxidative activity and ATP production rate were measured using the Agilent Seahorse XF Cell Mito Stress Test and the ATP Rate Assay, respectively in cultured wildtype and SGK1 knockout aortic VSMC from low-fat (LF) control and high-fat (HF) obese mice. To assess the importance of MCU, both assays were performed in the presence or absence of the MCU inhibitor, Ru360. Obesity caused a significant decrease in MCU abundance, but SGK1 deletion resulted in enrichment of MCU in VSMC. Ru360 treatment reversed the increase in basal mitochondrial respiration. We found that obesity reduced overall ATP production by diminishing ATP production from glycolysis and mitochondrial respiration. However, SGK1 deletion enhanced ATP production from glycolysis and mitochondrial respiration during obesity and this effect was attenuated by Ru360. These findings demonstrate that SGK1 negatively regulates MCU expression and activity and imply that augmentation of MCU-driven mitochondrial oxidative activity may underlie the protective effects of SGK1 inhibition on the vascular during obesity.

Vascular Smooth Muscle Cell Mechanotransduction Through Serum and Glucocorticoid Inducible Kinase-1 Promotes Interleukin-6 Production and Macrophage Accumulation in Murine Hypertension

Signaling through the serum and glucocorticoid inducible kinase-1 (SGK-1) can be mechanically activated. The objective of this investigation was to demonstrate that in vitro cyclic stretch of aortic vascular smooth muscle cells (VSMCs) and in vivo induction of hypertension (HTN) can cause SGK-1-dependent production of cytokines to promote macrophage accumulation in the murine abdominal aorta.

Abstract 328: Vascular Smooth Muscle Cell Mechanotransduction Through Serum And Glucocorticoid Inducible Kinase -1 Promotes Interleukin-6 Production And Macrophage Accumulation In Murine Hypertension

Objective: Signaling through the serum and glucocorticoid inducible kinase-1 (SGK-1) can be mechanically activated. The objective of this investigation was to demonstrate that in vitro cyclic stretch of aortic VSMCs and in vivo induction of hypertension (HTN) can cause SGK-1-dependent production of cytokines to promote macrophage accumulation in the murine abdominal aorta. Methods: HTN was induced in C57Bl/6 mice with AngiotensinII (AngII) infusion (1.46mg/kg/day x 21 days) and a subset of animals had systemic infusion of EMD638683 (2.5mg/kg/day x 21 days), a selective SGK-1 inhibitor. Aortas were digested and analyzed by flow cytometry for abundance of CD11b + /F4-80 + cells (macrophages) and serum was analyzed by ELISA to quantify IL-6 and MCP-1. Aortic VSMCs from wild-type (WT) and SGK-1 flox-induced knockout mice (FloxSGK-1KO) were subjected to 12% biaxial cyclic stretch for 12 hours +/- EMD638683 (10υM). Media was analyzed by ELISA. Statistical analysis included two-way ANOVA with significance at p&lt;0.05. Results: Having previously demonstrated that AngII infusion induced HTN and upregulated SGK-1 activity in the abdominal aorta, this experimentation indicated a concurrent trend for increased CD11b + /F4-80 + cells in the HTN group and marked reduction with EMD638683 infusion. Serum IL-6 levels were elevated in AngII-induced HTN (p&lt;0.05 vs Control), and reduced to baseline with concurrent EMD638683 treatment. This mirrored the increased abundance of IL-6 in media from Stretch WT VSMCs (p&lt;0.05 vs Static), and attenuation of the effect with EMD638683. Interestingly, MCP-1 was not detectable in the serum samples but was increased in media from Stretch WT VMSCs (p&lt;0.05 vs Static), suggesting potential paracrine or autocrine function of this cytokine within the vessel wall to support macrophage accumulation. Further supporting the integral role of mechanical signaling through SGK-1, media from Stretch FloxSGK-1KO VSMCs had no change in IL-6 or MCP-1 compared to Static. Conclusion: Mechanotransduction through SGK-1 is instrumental in pro-inflammatory cytokine production and aortic macrophage accumulation, therefore further investigation into targeting this kinase may present opportunities to modulate hypertensive vascular remodeling.

SGK1 mutation status can further stratify patients with germinal center B-cell-like diffuse large B-cell lymphoma into different prognostic subgroups.

There are over a 100 driver gene mutations in patients with diffuse large B‐cell lymphoma (DLBCL), but their clinical significance remains unclear. Here, we first analyzed the DLBCL dataset from the UK‐based Haematological Malignancy Research Network. Patients were divided into high‐ and low‐risk groups based on whether lymphoma progressed within 24 months. Genes showing significantly different frequencies between groups were selected. Survival data for patients with the selected mutant genes were analyzed. The results were validated using two other large databases to evaluate the relationship between the selected mutant genes and prognosis. The mutation frequencies of 11 genes (MYD88[L265P], SGK1, MPEG1, TP53, SPEN, NOTCH1, ETV6, TNFRSF14, MGA, CIITA, and PIM1) significantly differed between the high‐ and low‐risk groups. The relationships between these mutant genes and patient survival were analyzed. Patients who harbored SGK1 (serum and glucocorticoid‐inducible kinase 1) mutations exhibited the best prognosis. Most patients with SGK1 mutation are germinal center B‐cell (GCB) subtype. Among patients with GCB DLBCL, those harboring SGK1 mutations exhibited better prognosis than those without SGK1 mutations. Most SGK1 mutations were single‐base substitutions, primarily scattered throughout the catalytic domain‐encoding region. Multiple SGK1 mutations were identified in a single patient. Thus, SGK1 mutations are a marker of good prognosis for DLBCL and occur predominantly in the GCB subtype of DLBCL. SGK1 mutation status can further stratify patients with GCB DLBCL into different prognostic subgroups.

Antitumor activity of the dual PI3K/mTOR inhibitor gedatolisib and the involvement of ABCB1 in gedatolisib resistance in canine tumor cells.

The phosphatidylinositol 3-kinase/mammalian target of rapamycin (PI3K/mTOR) signaling pathway is a therapeutic target for various types of human tumors, and dual PI3K/mTOR inhibitors demonstrate antitumor activities in both preclinical and clinical studies. However, resistance mechanisms limit their abilities. As the molecular mechanisms involved in the cellular resistance are not clear in any canine tumors, an understanding of resistance mechanisms would support the potential use of dual PI3K/mTOR inhibitors in canine tumors. The antitumor activity of gedatolisib on cell viability, protein phosphorylation, and cell cycle distribution was assessed using 12 canine tumor cell lines from 6 types of tumors. In addition, the molecular determinants involved in the cellular sensitivity to gedatolisib were explored by investigating the involvement of serum-and-glucocorticoid-induced kinase 1 (SGK1), PIK3CA, and ATP-binding cassette, subfamily B, member 1 (ABCB1). The results demonstrated that gedatolisib decreased cell viability in all cell lines, with IC50 values <1 µM in 10 of the 12 lines. Gedatolisib inhibited Akt and mTOR complex 1 substrate phosphorylation and induced G0/G1 cell cycle arrest. However, certain cell lines with higher IC50 values were more resistant to these effects. These cell lines exhibited higher ABCB1 activity and the ABCB1 inhibitor cyclosporin A enhanced the decrease of cell viability caused by gedatolisib. SGK1 overexpression did not confer resistance to gedatolisib. The mutations of E545K and H1047R in PIK3CA were not observed. The present results indicated that gedatolisib decreased cell viability in canine tumor cell lines and ABCB1 played an important role in gedatolisib resistance, supporting the potential use of gedatolisib for canine tumors.

Eplerenone Prevents Cardiac Fibrosis by Inhibiting Angiogenesis in Unilateral Urinary Obstruction Rats.

Introduction Cardiovascular disease constitutes the leading cause of mortality in patients with chronic kidney disease (CKD), which is termed cardiorenal syndrome type 4 (CRS-4). Here, we report the development of pathological cardiac remodeling and fibrosis in unilateral urinary obstruction (UUO) rats. Methods Hematoxylin and eosin (H&E) staining was performed to observe the pathology of myocardial tissue. The degree of myocardial tissue fibrosis was observed by Masson and Sirius red staining. Immunohistochemical staining was applied to detect the expression of CD34 and CD105 in myocardial tissue, and immunofluorescent staining was performed to examine the expression of CD34, collagen I/collagen III, and alpha smooth muscle actin (α-SMA). The expression of the signal pathway-related proteins vascular endothelial growth factor A (VEGFA), vascular endothelial growth factor receptor 2 (VEGFR2), nuclear factor κB (NF-κB), and interleukin (IL)-1β was tested by western blotting. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the mRNA levels of serum and glucocorticoid-inducible kinase (SGK)-1, NF-κB, and interleukin-1β (IL-1β). Results The results showed the development of pathological cardiac remodeling and cardiac dysfunction in UUO rats. Moreover, there was more angiogenesis and endothelial-mesenchymal transition (End-MT) in the UUO group, and these effects were inhibited by eplerenone. Conclusions The results indicated that this cardiac fibrosis was associated with angiogenesis and that End-MT was related to aldosterone and mineralocorticoid receptor (MR) activation. Moreover, in association with the MR/IL-1β/VEGFA signaling pathway, early treatment with the MR antagonist eplerenone in rats with UUO-induced CKD may significantly attenuate MR activation and cardiac fibrosis.

Abstract 11618: Serum and Glucocorticoid Inducible Kinase-1 (SGK-1) Activity is Upregulated in Hypertension and Promotes IL-6 Expression to Drive Aortic Macrophage Accumulation

Introduction: The serum and glucocorticoid inducible kinase-1 (SGK-1) is a mechanosensitive kinase and it is hypothesized that SGK-1 activity is upregulated with elevated aortic tension to augment pro-inflammatory cytokine expression and promote macrophage accumulation to drive hypertensive remodeling. Methods: Hypertension (HTN) was induced in C57Bl/6 mice with AngiotensinII (AngII) infusion (1.46mg/kg/day x21days, n=4). Terminal procedure included blood pressure (SBP) quantification, aortic diameter (AoD) assessment, and harvest of infrarenal aorta. Abundance of SGK-1, pSGK-1, and the mature macrophage marker F4/80 was determined by immunoblot. The spontaneously hypertensive BPH/2 mice were also utilized and assessed for SBP, AoD, and target proteins (n=4). A subset of animals had systemic infusion of EMD638683, a selective SGK-1 inhibitor (2.5mg/kg/day x 21 days, n=4). Aortic VSMCs were subjected to 12% biaxial cyclic stretch for 3 and 12 hours +/- EMD638683 (10μM) with subsequent QPCR for IL-6 and MCP-1 expression. Statistical analysis included two-way ANOVA across treatment groups with significance at p&lt;0.05. Results: C57Bl/6+AngII mice and BPH/2 mice had significant elevation in SBP (p&lt;0.05) without change in AoD. The pSGK-1/SGK-1 and abundance F4/80 were increased in both models of HTN (p&lt;0.05) and decreased with systemic EMD638683 (p&lt;0.05), with no change in SBP. IL-6 expression was upregulated in VSMC that had Stretch for 3hrs (1.64 + 0.22 fold; p&lt;0.05) or 12hrs (1.99 + 0.33 fold; p&lt;0.05), and at both timepoints EMD638683 significantly inhibited IL-6 expression (p&lt;0.05 vs respective Stretch). MCP-1 expression was unchanged after 3hr Stretch, but it was significantly elevated following 12hr Stretch (2.05 + 0.38 fold; p&lt;0.05), and inhibited by EMD638683 (p&lt;0.05). This data suggests a biomechanical link between aortic VSMC mechanotransduction and cytokine production to promote macrophage accumulation, mediated in-part by SGK-1 activation. Conclusions: Mechanical stimuli can elevate SGK-1 activity and increase pro-inflammatory cytokine production to accumulate macrophages, which may lead to proteolytic aortic remodeling. Therefore, SGK-1 may represent a novel target to abrogate hypertensive aortic inflammation.