PIK3R1 fusion drives chemoresistance in ovarian cancer by activating ERK1/2 and inducing rod and ring-like structures

Gene fusions are common in high-grade serous ovarian cancer (HGSC). Such genetic lesions may promote tumorigenesis, but the pathogenic mechanisms are currently poorly understood. Here, we investigated the role of a PIK3R1-CCDC178 fusion identified from a patient with advanced HGSC. We show that the fusion induces HGSC cell migration by regulating ERK1/2 and increases resistance to platinum treatment. Platinum resistance was associated with rod and ring-like cellular structure formation. These structures contained, in addition to the fusion protein, CIN85, a key regulator of PI3K-AKT-mTOR signaling. Our data suggest that the fusion-driven structure formation induces a previously unrecognized cell survival and resistance mechanism, which depends on ERK1/2-activation.

Enhanced STAT3/PIK3R1/mTOR signaling triggers tubular cell inflammation and apoptosis in septic-induced acute kidney injury: implications for therapeutic intervention

Septic acute kidney injury (AKI) is a severe form of renal dysfunction associated with high morbidity and mortality rates. However, the pathophysiological mechanisms underlying septic AKI remain incompletely understood. Herein, we investigated the signaling pathways involved in septic AKI using the mouse models of lipopolysaccharide (LPS) treatment and cecal ligation and puncture (CLP). In these models, renal inflammation and tubular cell apoptosis were accompanied by the aberrant activation of the mechanistic target of rapamycin (mTOR) and the signal transducer and activator of transcription 3 (STAT3) signaling pathways. Pharmacological inhibition of either mTOR or STAT3 significantly improved renal function and reduced apoptosis and inflammation. Interestingly, inhibition of STAT3 with pharmacological inhibitors or small interfering RNA blocked LPS-induced mTOR activation in renal tubular cells, indicating a role of STAT3 in mTOR activation. Moreover, knockdown of STAT3 reduced the expression of the phosphoinositide-3-kinase regulatory subunit 1 (PIK3R1/p85α), a key subunit of the phosphatidylinositol 3-kinase for AKT and mTOR activation. Chromatin immunoprecipitation assay also proved the binding of STAT3 to PIK3R1 gene promoter in LPS-treated kidney tubular cells. In addition, knockdown of PIK3R1 suppressed mTOR activation during LPS treatment. These findings highlight the dysregulation of mTOR and STAT3 pathways as critical mechanisms underlying the inflammatory and apoptotic phenotypes observed in renal tubular cells during septic AKI, suggesting the STAT3/ PIK3R1/mTOR pathway as a therapeutic target of septic AKI.

Divergent roles of the regulatory subunits of class IA PI3K

The regulatory subunit of phosphatidylinositol 3-kinase (PI3K), known as p85, is a critical component in the insulin signaling pathway. Extensive research has shed light on the diverse roles played by the two isoforms of p85, namely p85α and p85β. The gene pik3r1 encodes p85α and its variants, p55α and p50α, while pik3r2 encodes p85β. These isoforms exhibit various activities depending on tissue types, nutrient availability, and cellular stoichiometry. Whole-body or liver-specific deletion of pik3r1 have shown to display increased insulin sensitivity and improved glucose homeostasis; however, skeletal muscle-specific deletion of p85α does not exhibit any significant effects on glucose homeostasis. On the other hand, whole-body deletion of pik3r2 shows improved insulin sensitivity with no significant impact on glucose tolerance. Meanwhile, liver-specific double knockout of pik3r1 and pik3r2 leads to reduced insulin sensitivity and glucose tolerance. In the context of obesity, upregulation of hepatic p85α or p85β has been shown to improve glucose homeostasis. However, hepatic overexpression of p85α in the absence of p50α and p55α results in increased insulin resistance in obese mice. p85α and p85β have distinctive roles in cancer development. p85α acts as a tumor suppressor, but p85β promotes tumor progression. In the immune system, p85α facilitates B cell development, while p85β regulates T cell differentiation and maturation. This review provides a comprehensive overview of the distinct functions attributed to p85α and p85β, highlighting their significance in various physiological processes, including insulin signaling, cancer development, and immune system regulation.

Long Non-coding RNA RMST Worsens Ischemic Stroke via MicroRNA-221-3p/PIK3R1/TGF-β Signaling Pathway

Much efforts have been made to probe the mechanism underlying ischemic stroke (IS). This study was proposed to uncover the role of long non-coding RNA rhabdomyosarcoma 2 related transcript (RMST) in IS through microRNA-221-3p (miR-221-3p)/phosphoinositide-3-kinase regulatory subunit 1 (PIK3R1)/transforming growth factor-β (TGF-β) axis. Neurological behavioral function, pathological changes in brain tissue, oxidative stress, and inflammation responses in middle cerebral artery occlusion (MCAO) mice were tested. RMST, miR-221-3p, PIK3R1, and TGF-β signaling-related protein expression in brain tissues of MCAO mice were detected. RMST and PIK3R1 were elevated, miR-221-3p was downregulated, and TGF-β pathway was activated in mice after MCAO. Restored miR-221-3p or depleted RMST improved neurological behavioral functions, relieved pathological injury in brain tissue, and repressed oxidative stress and inflammation in mice after MCAO. Depleted PIK3R1 or restored miR-221-3p offsets the negative effects of overexpressed RMST on mice with MCAO. The present work highlights that RMST augments IS through reducing miR-221-3p-mediated regulation of PIK3R1 and activating TGF-β pathway.

Quercetin alleviates chronic renal failure by targeting the PI3k/Akt pathway

Chronic renal failure (CRF) threatens human health greatly and attracts worldwide concerns of health professionals in the public health sector. In our preliminary study, we found that Compound capsule (Shengqing Jiangzhuo Capsule, SQJZJN) had a significant therapeutic effect on CRF. Quercetin is one of the main components of this Compound capsule. In this study, we investigated the effect of Quercetin monomer on CRF and the regulation of PI3k/Akt pathway. Network pharmacology analysis methods were employed to analyze the SQJZJN/Quercetin/PIK3R1 network relationships. In this study, a CRF rat model was prepared using the gavage adenine solution method and detected the indicators of Creatinine (Cr), Blood Urea Nitrogen (BUN), and Uric Acid (UA). After treating the rat model with Quercetin and PIK3R1-interfering lentivirus, respectively, we observed the changes on the histological morphology of the kidney and detected apoptosis using TUNEL staining. Gene and protein expression associated with renal function were detected using qPCR, WB and immunofluorescence. Quercetin was identified as the main ingredient of SQJZJN by the network pharmacological screening and Quercetin at 1.5 and 3 g/(kg.d) concentrations could effectively alleviate the CRF symptoms, reduce the levels of Cr, BUN, and UA, and markedly inhibit cell apoptosis demonstrated by the intragastric administration. Furthermore, the protein expression of p-PI3K, p-AKT, NLRP3, caspase1, AQP1, and AQP2 in all groups was detected by immunofluorescence and western blot assays, indicating that Quercetin could reduce the expression of NLRP3, caspase1, p-PI3k, and p-Akt, and increase the expression of AQP1 and AQP2 in the renal tissues of CRF rats. Being labeled with biotin and incubated with the total protein extracted from kidney tissues, Quercetin could bind to PIK3R1. Following the PIK3R1 interference lentivirus was injected into the CRF model rats by tail vein, the CRF symptoms were effectively alleviated in the PIK3R1 interference group, consistent with the effect of Quercetin. Taken together, Quercetin, a major component of SQJZJN, might minimize renal fibrosis and apoptosis in CRF rats by inhibiting the PI3k/Akt pathway through targeting PIK3R1. By regulating AQP1 and AQP2, both water retention and toxin accumulation were reduced.

MicroRNA-7 overexpression positively regulates the CD8+ SP cell development via targeting PIK3R1

microRNA-7 (miR-7), a distinct miRNA family member, has been reported to be involved in the biological functions of immune cells. However, the potential role of miR-7 in the CD8⁺ T cell development remains to be elucidated. In this study, we estimated the potential effects of miR-7 overexpression in the thymic CD8⁺ SP cell development using miR-7 overexpression mice. Our results showed that compared with those in control wild type (WT) mice, the volume, weight and total cell numbers of thymus in miR-7 overexpression (OE) mice increased significantly. The absolute cell number of CD8⁺ SP cells in miR-7 OE mice increased and its ability of activation and proliferation enhanced. Futhermore, we clarified that miR-7 overexpression had an intrinsic promote role in CD8⁺ SP cell development by adoptive cell transfer assay. Mechanistically, the expression level of PIK3R1, a target of miR-7, decreased significantly in CD8⁺ SP cells of miR-7 OE mice. Moreover, the expression level of phosphorylated (p)-AKT and p-ERK changed inversely and indicating that miR-7 overexpression impaired the balance of AKE and ERK pathways. In summary, our work reveals an essential role of miR-7 in promoting CD8⁺ SP cell development through the regulation of PIK3R1 and balance of AKT and ERK pathways.

Overexpression of PIK3R1 Promotes Bone Formation by Regulating Osteoblast Differentiation and Osteoclast Formation

In an effort to bolster our understanding of regulation of bone formation in the context of osteoporosis, we screened out differentially expressed genes in osteoporosis patients with high and low bone mineral density by bioinformatics analysis. PIK3R1 is increasingly being nominated as a pivotal mediator in the differentiation of osteoblasts and osteoclasts that is closely related to bone formation. However, the specific mechanisms underlying the way that PIK3R1 affects bone metabolism are not fully elucidated. We intended to examine the potential mechanism by which PIK3R1 regulates osteoblast differentiation. Enrichment analysis was therefore carried out for differentially expressed genes. We noted that the estrogen signaling pathway, TNF signaling pathway, and osteoclast differentiation were markedly associated with ossification, and they displayed enrichment in PIK3R1. Based on western blot, qRT-PCR, and differentiation analysis in vitro, we found that upregulation of PIK3R1 enhanced osteoblastic differentiation, as evidenced by increased levels of investigated osteoblast-related genes as well as activities of ALP and ARS, while it notably decreased levels of investigated osteoclast-related genes. On the contrary, downregulation of PIK3R1 decreased levels of osteoblast-related genes and increased levels of osteoclast-related genes. Besides, in vitro experiments revealed that PIK3R1 facilitated proliferation and repressed apoptosis of osteoblasts but had an opposite impact on osteoclasts. In summary, PIK3R1 exhibits an osteoprotective effect via regulating osteoblast differentiation, which can be represented as a promising therapeutic target for osteoporosis.

The PI-3-Kinase P110α Catalytic Subunit of T Lymphocytes Modulates Collagen-Induced Arthritis

The phosphatidylinositol 3-kinase (PI3K) family of enzymes plays a determinant role in inflammation and autoimmune responses. However, the implication of the different isoforms of catalytic subunits in these processes is not clear. Rheumatoid arthritis (RA) is a chronic, systemic autoimmune inflammatory disease that entails innate and adaptive immune response elements in which PI3K is a potential hub for immune modulation. In a mouse transgenic model with T-cell-specific deletion of p110α catalytic chain (p110α-/-ΔT), we show the modulation of collagen-induced arthritis (CIA) by this isoform of PI3K. In established arthritis, p110α-/-ΔT mice show decreased prevalence of illness than their control siblings, higher IgG1 titers and lower levels of IL-6 in serum, together with decreased ex vivo Collagen II (CII)-induced proliferation, IL-17A secretion and proportion of naive T cells in the lymph nodes. In a pre-arthritis phase, at 13 days post-Ag, T-cell-specific deletion of p110α chain induced an increased, less pathogenic IgG1/IgG2a antibodies ratio; changes in the fraction of naive and effector CD4+ subpopulations; and an increased number of CXCR5+ T cells in the draining lymph nodes of the p110α-/-ΔT mice. Strikingly, T-cell blasts in vitro obtained from non-immunized p110α-/-ΔT mice showed an increased expression of CXCR5, CD44 and ICOS surface markers and defective ICOS-induced signaling towards Akt phosphorylation. These results, plus the accumulation of cells in the lymph nodes in the early phase of the process, could explain the diminished illness incidence and prevalence in the p110α-/-ΔT mice and suggests a modulation of CIA by the p110α catalytic chain of PI3K, opening new avenues of intervention in T-cell-directed therapies to autoimmune diseases.

SUMOylation modulates the stability and function of PI3K-p110β

Class I PI3K are heterodimers composed of a p85 regulatory subunit and a p110 catalytic subunit involved in multiple cellular functions. Recently, the catalytic subunit p110β has emerged as a class I PI3K isoform playing a major role in tumorigenesis. Understanding its regulation is crucial for the control of the PI3K pathway in p110β-driven cancers. Here we sought to evaluate the putative regulation of p110β by SUMO. Our data show that p110β can be modified by SUMO1 and SUMO2 in vitro, in transfected cells and under completely endogenous conditions, supporting the physiological relevance of p110β SUMOylation. We identify lysine residue 952, located at the activation loop of p110β, as essential for SUMOylation. SUMOylation of p110β stabilizes the protein increasing its activation of AKT which promotes cell growth and oncogenic transformation. Finally, we show that the regulatory subunit p85β counteracts the conjugation of SUMO to p110β. In summary, our data reveal that SUMO is a novel p110β interacting partner with a positive effect on the activation of the PI3K pathway.

Antidepressant mechanism and active compounds of saffron from network pharmacology study

Saffron has been applied in depression treatment, but its antidepressant compounds and mechanisms are unclear. In this research, a network pharmacology-based method was proposed to screen the active compounds and the potential mechanisms of saffron for depression treatment. Firstly, the chemical compounds of saffron were collected from literature and filtered by drug-like prediction. Secondly, common targets, by comparing the targets of saffron predicted by Pharm Mapper server with targets associated with depression collected from Genecards, were regarded as the antidepressant targets of saffron. Thirdly, common targets were mapped to KEGG pathways, considered as the pathways related with the antidepressant effects of saffron. Finally, the network of compounds-targets-pathways was constructed and analyzed by cytoscape 3.4.0. Ten compounds including crocetin, picrocrocin, (1R, 5S, 6R)-5-(hydroxymethyl)- 4, 4, 6-trimethyl-7-Oxabicyclo[4.1.0]heptan-2-one and its glycoside were screened as the main antidepressant compounds, some of which were reported for the first time. They might have effective treatment for depression by acting on targets, such as MAP2K1, MAPK1, HRAS, PIK3R1, ALB and AKT1 and pathways related with immune system, signal transduction and so on. This study provided a new insight into the antidepressant mechanism and active compounds of saffron, which also had a guiding effect on later experiments.

Gab2 deficiency suppresses high-fat diet-induced obesity by reducing adipose tissue inflammation and increasing brown adipose function in mice

Obesity is caused by a long-term imbalance between energy intake and consumption and is regulated by multiple signals. This study investigated the effect of signaling scaffolding protein Gab2 on obesity and its relevant regulation mechanism. Gab2 knockout (KO) and wild-type (WT) mice were fed with a standard diet (SD) or high-fat diet (HFD) for 12 weeks. The results showed that the a high-fat diet-induced Gab2 expression in adipose tissues, but deletion of Gab2 attenuated weight gain and improved glucose tolerance in mice fed with a high-fat diet. White adipose tissue and systemic inflammations were reduced in HFD-fed Gab2 deficiency mice. Gab2 deficiency increased the expression of Ucp1 and other thermogenic genes in brown adipose tissue. Furthermore, the regulation of Gab2 on the mature differentiation and function of adipocytes was investigated in vitro using primary or immortalized brown preadipocytes. The expression of brown fat-selective genes was found to be elevated in differentiated adipocytes without Gab2. The mechanism of Gab2 regulating Ucp1 expression in brown adipocytes involved with its downstream PI3K (p85)-Akt-FoxO1 signaling pathway. Our research suggests that deletion of Gab2 suppresses diet-induced obesity by multiple pathways and Gab2 may be a novel therapeutic target for the treatment of obesity and associated complications.

MiR-126-3p-Enriched Extracellular Vesicles from Hypoxia-Preconditioned VSC 4.1 Neurons Attenuate Ischaemia-Reperfusion-Induced Pain Hypersensitivity by Regulating the PIK3R2-Mediated Pathway

Recent evidence suggests that hypoxia preconditioning can alter the microRNA (miRNA) profile of extracellular vesicles (EVs) and has better neuroprotective effects when enriched miRs are delivered to recipients. However, the roles of exosomal miRNAs in regulating ischaemia-reperfusion (IR)-induced pain hypersensitivity are largely unknown. Thus, we isolated EVs from normoxia-conditioned neurons (Nor-VSC EVs) and Hypo-VSC EVs by ultracentrifugation. After the initial screening by a microarray analysis and quantitative RT-PCR (qRT-PCR), miR-126-3p, which was detected as the most altered miR in the Hypo-VSC EVs, was further confirmed by applying GW4869 to inhibit exosomal secretion. Moreover, transfection with a miR-126 mimic obviously increased miR-126-3p expression in Nor-VSC EVs, whereas a miR-126 inhibitor prevented the increase in miR-126-3p in Hypo-VSC EVs. A rat model of pain was established by performing 8-min occlusion of the aorta. Following IR, compared with the Nor-VSC EVs- or antagomir-126-injected rats, the Hypo-VSC EVs-injected rats displayed improved pain hypersensitivity demonstrated as higher PWT and PWL values. Mechanistically, PIK3R2 is a target of miR-126-3p and might be a modulator of the phosphoinositide 3-kinase (PI3K)/Akt pathway as the PIK3R2 and PI3K immunoreactivities in each group were changed in opposite directions. Compared with the controls, higher protein levels of PI3K and phosphorylated Akt but lower levels of phosphorylated nuclear factor-κ B (NF-κB), tumour necrosis factor (TNF)-α and interleukin (IL)-1β were detected in the spinal cords of the Hypo-VSC EVs-injected rats, and these effects were impaired by an injection of Hypo-VSC EVs combined with antagomir-126. Collectively, the miR-126-3p-enriched Hypo-VSC EVs attenuated IR-induced pain hypersensitivity by restoring miR-126-3p expression in the injured spinal cord and subsequently modulating PIK3R2-mediated PI3K/Akt and NF-κB signalling pathways.

miR-126 Mimic Counteracts the Increased Secretion of VEGF-A Induced by High Glucose in ARPE-19 Cells

Vascular endothelial growth factor-A (VEGF-A) has a pathologic role in microvascular diabetic complication, such as diabetic retinopathy (DR). miR-126 plays an important role in vascular development and angiogenesis by regulating the expression of VEGF-A. Since levels of miR-126 have been found downregulated in diabetes, this study is aimed at investigating whether hyperglycemia affects expression of miR-126 in a retinal pigment epithelium cell line. ARPE-19 cells were transfected with miR-126 inhibitor or with miR-126 mimic and the respective scramble negative control. After 24 hours, medium was replaced and cells were cultured for 24 hours in normal (CTR) or diabetic condition (HG). Then, we analyzed mRNA levels of miR-126, VEGF-A, PI3KR2, and SPRED1. We also evaluated protein amount of HIF-1α, PI3KR2, and SPRED1 and VEGF-A secretion. The results showed that exposure of ARPE-19 cells to HG significantly decreased miR-126 levels; mRNA levels of VEGF-A and PI3KR2 were inversely correlated with those of miR-126. Overexpression of miR-126 under HG restored HIF-1α expression and VEGF-A secretion to the level of CTR cells. These results indicate that reduced levels of miR-126 may contribute to DR progression by increasing expression of VEGF-A in RPE cells. In addition, we provide evidence that upregulation of miR-126 in RPE cells counteracts the rise of VEGF-A secretion induced by hyperglycemia. In conclusion, our data support a role of miR-126 mimic-approach in counteracting proangiogenic effects of hyperglycemia.

Truncation of Pik3r1 causes severe insulin resistance uncoupled from obesity and dyslipidaemia by increased energy expenditure

OBJECTIVE

Insulin signalling via phosphoinositide 3-kinase (PI3K) requires PIK3R1-encoded regulatory subunits. C-terminal PIK3R1 mutations cause SHORT syndrome, as well as lipodystrophy and insulin resistance (IR), surprisingly without fatty liver or metabolic dyslipidaemia. We sought to investigate this discordance.

METHODS

The human pathogenic Pik3r1 Y657∗ mutation was knocked into mice by homologous recombination. Growth, body composition, bioenergetic and metabolic profiles were investigated on chow and high-fat diet (HFD). We examined adipose and liver histology, and assessed liver responses to fasting and refeeding transcriptomically.

RESULTS

Like humans with SHORT syndrome, Pik3r1WT/Y657∗ mice were small with severe IR, and adipose expansion on HFD was markedly reduced. Also as in humans, plasma lipid concentrations were low, and insulin-stimulated hepatic lipogenesis was not increased despite hyperinsulinemia. At odds with lipodystrophy, however, no adipocyte hypertrophy nor adipose inflammation was found. Liver lipogenic gene expression was not significantly altered, and unbiased transcriptomics showed only minor changes, including evidence of reduced endoplasmic reticulum stress in the fed state and diminished Rictor-dependent transcription on fasting. Increased energy expenditure, which was not explained by hyperglycaemia nor intestinal malabsorption, provided an alternative explanation for the uncoupling of IR from dyslipidaemia.

CONCLUSIONS

Pik3r1 dysfunction in mice phenocopies the IR and reduced adiposity without lipotoxicity of human SHORT syndrome. Decreased adiposity may not reflect bona fide lipodystrophy, but rather, increased energy expenditure, and we suggest that further study of brown adipose tissue in both humans and mice is warranted.

High glucose concentration produces a short-term increase in pERK1/2 and p85 proteins, having a direct angiogenetic effect by an action similar to VEGF

AIMS

Excessive glucose serum concentration, endothelial dysfunction and microangiopathy are key features of diabetes mellitus, being both diagnostic parameters and pathogenetic mechanisms. Vascular endothelial growth factor (VEGF) is importantly implicated in the physiology and pathology of blood vessels, including diabetic vascular damage.

METHODS

These factors certainly affect endothelial cells, and to evaluate mechanisms involved, we took advantage of telomerase-immortalized human microvascular endothelial (TIME) cells. TIME cells were exposed to different glucose concentrations and to VEGF treatments. Culture conditions also included the use of basement membrane extract, as an in vitro differentiation model. Cell morphology was then evaluated in the different conditions, and cellular proteins were extracted to analyze specific protein products by Western blot.

RESULTS

High glucose concentrations and VEGF did substantially affect neither morphology nor growth of cultured TIME cells, while both considerably increased differentiation into "capillary-like" structures when cells were cultured on basement membrane extract.

CONCLUSIONS

Under these conditions, high glucose concentration and VEGF also produced a short-term increase in pERK1/2 and p85 proteins, while total and phosphorylated AKT were not affected. These data suggest a direct angiogenetic effect of glucose, affecting intracellular transduction mechanisms with an action similar to that of VEGF. This effect on endothelial cell proliferation and differentiation could be part of pathogenetic mechanisms producing diabetic microvascular alterations.

MiR-155 promotes interleukin-1β-induced chondrocyte apoptosis and catabolic activity by targeting PIK3R1-mediated PI3K/Akt pathway

Osteoarthritis (OA) is a common joint disease characterized by progressive cartilage degradation, in which elevated chondrocyte apoptosis and catabolic activity play an important role. MicroRNA-155 (miR-155) has recently been shown to regulate apoptosis and catabolic activity in some pathological circumstances, yet, whether and how miR-155 is associated with OA pathology remain unexplored. We report here that miR-155 level is significantly up-regulated in human OA cartilage biopsies and also in primary chondrocytes stimulated by interleukin-1β (IL-1β), a pivotal pro-catabolic factor promoting cartilage degradation. Moreover, miR-155 inhibition attenuates and its overexpression promotes IL-1β-induced apoptosis and catabolic activity in chondrocytes in vitro. We also demonstrate that the PIK3R1 (p85α regulatory subunit of phosphoinositide 3-kinase (PI3K)) is a target of miR-155 in chondrocytes, and more importantly, PIK3R1 restoration abrogates miR-155 effects on chondrocyte apoptosis and catabolic activity. Mechanistically, PIK3R1 positively regulates the transduction of PI3K/Akt pathway, and a specific Akt inhibitor reverses miR-155 effects on promoting chondrocyte apoptosis and catabolic activity, phenocopying the results obtained via PIK3R1 knockdown, hence establishing that miR-155 promotes chondrocyte apoptosis and catabolic activity through targeting PIK3R1-mediated PI3K/Akt pathway activation. Altogether, our study discovers novel roles and mechanisms of miR-155 in regulating chondrocyte apoptosis and catabolic activity, providing an implication for therapeutically intervening cartilage degradation and OA progression.

Changes in DNA Methylation and Gene Expression of Insulin and Obesity-Related Gene PIK3R1 after Roux-en-Y Gastric Bypass

Weight regulation and the magnitude of weight loss after a Roux-en-Y gastric bypass (RYGB) can be genetically determined. DNA methylation patterns and the expression of some genes can be altered after weight loss interventions, including RYGB. The present study aimed to evaluate how the gene expression and DNA methylation of PIK3R1, an obesity and insulin-related gene, change after RYGB. Blood samples were obtained from 13 women (35.9 ± 9.2 years) with severe obesity before and six months after surgical procedure. Whole blood transcriptome and epigenomic patterns were assessed by microarray-based, genome-wide technologies. A total of 1966 differentially expressed genes were identified in the pre- and postoperative periods of RYGB. From these, we observed that genes involved in obesity and insulin pathways were upregulated after surgery. Then, the PIK3R1 gene was selected for further RT-qPCR analysis and cytosine-guanine nucleotide (CpG) sites methylation evaluation. We observed that the PI3KR1 gene was upregulated, and six DNA methylation CpG sites were differently methylated after bariatric surgery. In conclusion, we found that RYGB upregulates genes involved in obesity and insulin pathways.

Glyphosate induces lymphocyte cell dysfunction and apoptosis via regulation of miR-203 targeting of PIK3R1 in common carp (Cyprinus carpio L.)

Glyphosate is a widely used pesticide worldwide. The problem surrounding glyphosate is worth investigating, especially with its increased use, and an increasing number of studies have found that the toxic effect of glyphosate is objective. MiR-203 was seldom found in fish diseases or glyphosate researches. This article aims to explore the effect of miR-203 on carp lymphocytes during glyphosate exposure. Therefore, acridine orange/ethidium bromide (AO/EB) and flow cytometry were carried out to evaluate apoptosis, and we also detected CYPs (CYP1A1, CYP1B1, CYP1C), cytokine secretion (IL-1β, IL-8, IL-10, IFN-γ, TNF-α), inflammatory factors (NF-κB, cox-2), and the expression of miR-203 and the PI3K/AKT pathway by RT-PCR and Western blot analyses. Our results demonstrated that glyphosate exposure could induce lymphocyte apoptosis via regulation of miR-203 targeting of PI3K/AKT, which was accompanied by CYPs activation, abnormal cytokine expression and an inflammatory response. These results show that glyphosate is not nontoxic to fish and provide new insights for the usage of glyphosate as an herbicide in the future.

p85β regulates autophagic degradation of AXL to activate oncogenic signaling

PIK3R2 encodes the p85β regulatory subunit of phosphatidylinositol 3-kinase and is frequently amplified in cancers. The signaling mechanism and therapeutic implication of p85β are poorly understood. Here we report that p85β upregulates the protein level of the receptor tyrosine kinase AXL to induce oncogenic signaling in ovarian cancer. p85β activates p110 activity and AKT-independent PDK1/SGK3 signaling to promote tumorigenic phenotypes, which are all abolished upon inhibition of AXL. At the molecular level, p85β alters the phosphorylation of TRIM2 (an E3 ligase) and optineurin (an autophagy receptor), which mediate the selective regulation of AXL by p85β, thereby disrupting the autophagic degradation of the AXL protein. Therapeutically, p85β expression renders ovarian cancer cells vulnerable to inhibitors of AXL, p110, or PDK1. Conversely, p85β-depleted cells are less sensitive to these inhibitors. Together, our findings provide a rationale for pharmacological blockade of the AXL signaling axis in PIK3R2-amplified ovarian cancer.

miR-155 inhibits oxidized low-density lipoprotein-induced apoptosis in different cell models by targeting the p85α/AKT pathway

The apoptosis of vascular endothelial cells (VECs), vascular smooth muscle cells (VSMCs), and macrophages directly causes the instability or rupture of atherosclerotic plaques. Accumulating evidence suggests that oxidized low-density lipoprotein (OxLDL) could induce apoptosis via endogenous or exogenous pathways. Interestingly, it has been reported that microRNA155 (miR-155) plays a pivotal role in the regulation of apoptosis. Here, we hypothesized that overexpression of miR-155 could inhibit OxLDL-induced apoptosis by targeting the p85α/AKT pathway. In this study, we established models of OxLDL-induced apoptosis in mouse VECs, VSMCs, and macrophages. Furthermore, we explored the effects of miR-155 expression on the apoptosis of different cells, and ultimately revealed whether miR-155 regulated apoptosis by targeting the p85α/AKT pathway. The results demonstrated that miR-155 inhibited p85α expression and attenuated VEC, VSMC, and macrophage apoptosis, at least in part by suppressing the expression of p85α-activated AKT to inhibit apoptosis. Our findings collectively suggested that miR-155 attenuated OxLDL-mediated apoptosis in different cells by targeting p85α, supporting its possible therapeutic role in atherosclerosis.

PIK3R1W624R Is an Actionable Mutation in High Grade Serous Ovarian Carcinoma

Identifying cancer drivers and actionable mutations is critical for precision oncology. In epithelial ovarian cancer (EOC) the majority of mutations lack biological or clinical validation. We fully characterized 43 lines of Patient-Derived Xenografts (PDXs) and performed copy number analysis and whole exome sequencing of 12 lines derived from naïve, high grade EOCs. Pyrosequencing allowed quantifying mutations in the source tumours. Drug response was assayed on PDX Derived Tumour Cells (PDTCs) and in vivo on PDXs. We identified a PIK3R1W624R variant in PDXs from a high grade serous EOC. Allele frequencies of PIK3R1W624R in all the passaged PDXs and in samples of the source tumour suggested that it was truncal and thus possibly a driver mutation. After inconclusive results in silico analyses, PDTCs and PDXs allowed the showing actionability of PIK3R1W624R and addiction of PIK3R1W624R carrying cells to inhibitors of the PI3K/AKT/mTOR pathway. It is noteworthy that PIK3R1 encodes the p85α regulatory subunit of PI3K, that is very rarely mutated in EOC. The PIK3R1W624R mutation is located in the cSH2 domain of the p85α that has never been involved in oncogenesis. These data show that patient-derived models are irreplaceable in their role of unveiling unpredicted driver and actionable variants in advanced ovarian cancer.

Overexpression of tripartite motif containing 26 inhibits non-small cell lung cancer cell growth by suppressing PI3K/AKT signaling

It has been reported that tripartite motif containing 26 (TRIM26) is involved in the tumorigenesis of some cancers, but its function in non-small cell lung cancer (NSCLC) is still unclear. In this study, we found that TRIM26 was markedly down-regulated in both of NSCLC tumor tissues and cell lines. Additionally, high expression of TRIM26 in NSCLC patients predicted a positive index for patients' overall survival. What is more, overexpression of TRIM26 significantly suppressed NSCLC cell growth. Our further studies indicated that overexpression of TRIM26 inhibited the phosphorylation of PI3K p85 and AKT. And overexpressed TRIM26 regulated cell cycle-related genes' expression, including downregulating CDK4, Cyclin A, Cyclin D1, Cyclin D3, and Cyclin E, and upregulating p27 expression. Finally, we found that TRIM26 up-regulated PTEN expression by stabilizing PTEN protein in NSCLC cells. Collectively, our present study indicated that TRIM26 was decreased in NSCLC and overexpression of TRIM26 inhibited NSCLC cell growth by suppressing PI3K/AKT pathway, which suggested that TRIM26 could be as a potential target for the treatment of NSCLC in the future.

Impairment of Membrane Lipid Homeostasis by Bichalcone Analog TSWU-BR4 Attenuates Function of GRP78 in Regulation of the Oxidative Balance and Invasion of Cancer Cells

The specialized cholesterol/sphingolipid-rich membrane domains termed lipid rafts are highly dynamic in the cancer cells, which rapidly assemble effector molecules to form a sorting platform essential for oncogenic signaling transduction in response to extra- or intracellular stimuli. Density-based membrane flotation, subcellular fractionation, cell surface biotinylation, and co-immunoprecipitation analyses of bichalcone analog ((E)-1-(4-Hydroxy-3-((4-(4-((E)-3-(pyridin-3-yl)acryloyl)phenyl)piperazin-1-yl)methyl)phenyl)-3-(pyridin-3-yl)prop-2-en-1-one (TSWU-BR4)-treated cancer cells showed dissociation between GRP78 and p85α conferring the recruitment of PTEN to lipid raft membranes associated with p85α. Ectopic expression of GRP78 could overcome induction of lipid raft membrane-associated p85α–unphosphorylated PTEN complex formation and suppression of GRP78−PI3K−Akt−GTP-Rac1-mediated and GRP78-regulated PERK−Nrf2 antioxidant pathway and cancer cell invasion by TSWU-BR4. Using specific inducer, inhibitor, or short hairpin RNA for ASM demonstrated that induction of the lipid raft membrane localization and activation of ASM by TSWU-BR4 is responsible for perturbing homeostasis of cholesterol and ceramide levels in the lipid raft and ER membranes, leading to alteration of GRP78 membrane trafficking and subsequently inducing p85α–unphosphorylated PTEN complex formation, causing disruption of GRP78−PI3K−Akt−GTP-Rac1-mediated signal and ER membrane-associated GRP78-regulated oxidative stress balance, thus inhibiting cancer cell invasion. The involvement of the enrichment of ceramide to lipid raft membranes in inhibition of NF-κB-mediated MMP-2 expression was confirmed through attenuation of NF-κB activation using C2-ceramide, NF-κB specific inhibitors, ectopic expression of NF-κB p65, MMP-2 promoter-driven luciferase, and NF-κB-dependent reporter genes. In conclusion, localization of ASM in the lipid raft membranes by TSWU-BR4 is a key event for initiating formation of ceramide-enriched lipid raft membrane platforms, which causes delocalization of GRP78 from the lipid raft and ER membranes to the cytosol and formation of p85α–unphosphorylated PTEN complexes to attenuate the GRP78-regulated oxidative stress balance and GRP78−p85α−Akt−GTP-Rac1−NF-κB−MMP-2-mediated cancer cell invasion.

p85α Inactivates MMP-2 and Suppresses Bladder Cancer Invasion by Inhibiting MMP-14 Transcription and TIMP-2 Degradation

Recent studies show p85α up-regulates epidermal growth factor (EGF) receptor, thereby promoting malignant cell transformation and migration in normal mouse embryonic fibroblasts (MEFs). However, the potential role of p85α in human bladder cancer (BC) remains unknown. Here, we show that p85α is down-regulated in BC tumor tissues. Ectopic expression of p85α inhibited cell invasion, but not migration, whereas p85α knockdown promoted invasion in BC cells, revealing that p85α inhibits BC invasion. Overexpression of kinase-deficient p110 in T24 T(p85α) cells inhibited BC cell migration, but not invasion, suggesting that the inhibition of p85α on invasion is independent of PI3K activity. The effect of p85α on inhibiting BC invasion was mediated by the inactivation of MMP-2 concomitant with the up-regulation of TIMP-2 and down-regulation of MMP-14. Mechanistic studies revealed c-Jun inactivation was associated with p85α knockdown-induced MMP-14 expression, and down-regulated miR-190, leading to ATG7 mRNA degradation. This suppressed the autophagy-dependent removal of TIMP-2 in human BC cells. The present results identify a novel function of p85α and clarify the mechanisms underlying its inhibition of BC invasion, providing insight into the role of p85α in normal and cancer cells.

PI3Kβ-A Versatile Transducer for GPCR, RTK, and Small GTPase Signaling

The phosphoinositide 3-kinase (PI3K) family includes eight distinct catalytic subunits and seven regulatory subunits. Only two PI3Ks are directly regulated downstream from G protein-coupled receptors (GPCRs): the class I enzymes PI3Kβ and PI3Kγ. Both enzymes produce phosphatidylinositol 3,4,5-trisposphate in vivo and are regulated by both heterotrimeric G proteins and small GTPases from the Ras or Rho families. However, PI3Kβ is also regulated by direct interactions with receptor tyrosine kinases (RTKs) and their tyrosine phosphorylated substrates, and similar to the class II and III PI3Ks, it binds activated Rab5. The unusually complex regulation of PI3Kβ by small and trimeric G proteins and RTKs leads to a rich landscape of signaling responses at the cellular and organismic levels. This review focuses first on the regulation of PI3Kβ activity in vitro and in cells, and then summarizes the biology of PI3Kβ signaling in distinct tissues and in human disease.

Impact of p85α Alterations in Cancer

The phosphatidylinositol 3-kinase (PI3K) pathway plays a central role in the regulation of cell signaling, proliferation, survival, migration and vesicle trafficking in normal cells and is frequently deregulated in many cancers. The p85α protein is the most characterized regulatory subunit of the class IA PI3Ks, best known for its regulation of the p110-PI3K catalytic subunit. In this review, we will discuss the impact of p85α mutations or alterations in expression levels on the proteins p85α is known to bind and regulate. We will focus on alterations within the N-terminal half of p85α that primarily regulate Rab5 and some members of the Rho-family of GTPases, as well as those that regulate PTEN (phosphatase and tensin homologue deleted on chromosome 10), the enzyme that directly counteracts PI3K signaling. We highlight recent data, mapping the interaction surfaces of the PTEN⁻p85α breakpoint cluster region homology (BH) domain, which sheds new light on key residues in both proteins. As a multifunctional protein that binds and regulates many different proteins, p85α mutations at different sites have different impacts in cancer and would necessarily require distinct treatment strategies to be effective.

Quantitation of class IA PI3Ks in mice reveals p110-free-p85s and isoform-selective subunit associations and recruitment to receptors

Class IA PI3Ks have many roles in health and disease. The rules that govern intersubunit and receptor associations, however, remain unclear. We engineered mouse lines in which individual endogenous class IA PI3K subunits were C-terminally tagged with 17aa that could be biotinylated in vivo. Using these tools we quantified PI3K subunits in streptavidin or PDGFR pull-downs and cell lysates. This revealed that p85α and β bound equivalently to p110α or p110β but p85α bound preferentially to p110δ. p85s were found in molar-excess over p110s in a number of contexts including MEFs (p85β, 20%) and liver (p85α, 30%). In serum-starved MEFs, p110-free-p85s were preferentially, compared with heterodimeric p85s, bound to PDGFRs, consistent with in vitro assays that demonstrated they bound PDGFR-based tyrosine-phosphorylated peptides with higher affinity and co-operativity; suggesting they may act to tune a PI3K activation threshold. p110α-heterodimers were recruited 5-6× more efficiently than p110β-heterodimers to activated PDGFRs in MEFs or to PDGFR-based tyrosine-phosphorylated peptides in MEF-lysates. This suggests that PI3Kα has a higher affinity for relevant tyrosine-phosphorylated motifs than PI3Kβ. Nevertheless, PI3Kβ contributes substantially to acute PDGF-stimulation of PIP3 and PKB in MEFs because it is synergistically, and possibly sequentially, activated by receptor-recruitment and small GTPases (Rac/CDC42) via its RBD, whereas parallel activation of PI3Kα is independent of its RBD. These results begin to provide molecular clarity to the rules of engagement between class IA PI3K subunits in vivo and past work describing "excess p85," p85α as a tumor suppressor, and differential receptor activation of PI3Kα and PI3Kβ.

β-arrestin 2 mediates cardiac ischemia-reperfusion injury via inhibiting GPCR-independent cell survival signalling

Aims

Ischemic heart disease is a leading cause of morbidity and mortality worldwide. Although timely restoration of coronary blood flow (reperfusion) is the most effective therapeutics of myocardial infarction, reperfusion causes further cardiac damage, i.e. ischemia-reperfusion (I/R) injury. β-arrestins (Arrbs) have been traditionally defined as negative regulators of G protein-coupled receptor (GPCR) signalling, but recent studies have shown that they are essential for G protein-independent, GPCR-mediated biased signalling. Several ligands have been reported to be cardioprotective via Arrbs dependent pathway. However, it is unclear whether Arrbs exert receptor-independent physiological or pathological functions in the heart. Here, we sought to determine whether and how Arrbs play a role in regulating cardiomyocyte viability and myocardial remodelling following I/R injury.

Methods and results

The expression of β-arrestin 2 (Arrb2), but not β-arrestin 1 (Arrb1), is upregulated in rat hearts subjected to I/R injury, or in cultured neonatal rat cardiomyocytes treated with hypoxia-reoxygenation (H/R) injury. Deficiency of Arrb2 in cultured neonatal rat cardiomyocytes alleviates H/R-induced cardiomyocyte death and Arrb2-/- mice are resistant to myocardial damage caused by I/R injury. In contrast, upregulation of Arrb2 triggers cardiomyocyte death and exaggerates I/R (or H/R)-induced detrimental effects. Mechanically, Arrb2 induces cardiomyocyte death by interacting with the p85 subunit of PI3K, and negatively regulating the formation of p85-PI3K/CaV3 survival complex, thus blocking activation of PI3K-Akt-GSK3β cell survival signalling pathway.

Conclusion

We define an upregulation of Arrb2 as a pathogenic factor in cardiac I/R injury, and also reveal a novel GPCR-independent mechanism of Arrb2-mediated cell death signalling in the heart.

Pharmacological inactivation of the PI3K p110δ prevents breast tumour progression by targeting cancer cells and macrophages

Patient selection for PI3K-targeted solid cancer treatment was based on the PIK3CA/PTEN mutational status. However, it is increasingly clear that this is not a good predictor of the response of breast cancer cells to the anti-proliferative effect of PI3K inhibitors, indicating that isoform(s) other than p110α may modulate cancer cells sensitivity to PI3K inhibition. Surprisingly, we found that although no mutations in the p110δ subunit have been detected thus far in breast cancer, the expression of p110δ becomes gradually elevated during human breast cancer progression from grade I to grade III. Moreover, pharmacological inactivation of p110δ in mice abrogated the formation of tumours and the recruitment of macrophages to tumour sites and strongly affected the survival, proliferation and apoptosis of grafted tumour cells. Pharmacological inactivation of p110δ in mice with defective macrophages or in mice with normal macrophages but grafted with p110δ-lacking tumours suppressed only partly tumour growth, indicating a requisite role of p110δ in both macrophages and cancer cells in tumour progression. Adoptive transfer of δD910A/D910A macrophages into mice with defected macrophages suppressed tumour growth, eliminated the recruitment of macrophages to tumour sites and prevented metastasis compared with mice that received WT macrophages further establishing that inactivation of p110δ in macrophage prevents tumour progression. Our work provides the first in vivo evidence for a critical role of p110δ in cancer cells and macrophages during solid tumour growth and may pave the way for the use of p110δ inhibitors in breast cancer treatment.

LZTS2 inhibits PI3K/AKT activation and radioresistance in nasopharyngeal carcinoma by interacting with p85

Phosphoinositide 3-kinase (PI3K) activity is aberrantly activated in nasopharyngeal carcinoma. However, the underlying mechanisms remain unclear. Here, we found that Leucine zipper tumor suppressor 2 (LZTS2) was downregulated and predicted poor prognosis in nasopharyngeal carcinoma patients. Furthermore, we identified the PI3K subunit p85 as a novel LZTS2-interacting protein using an unbiased proteomics approach. Moreover, we demonstrated that LZTS2 competes with p110 for p85 binding and inhibits activation of the PI3K/AKT signaling pathway. Functionally, we showed that LZTS2 suppresses tumorigenesis and radioresistance in nasopharyngeal carcinoma in a p85-dependent manner. Taken together, our results not only provide understanding of the molecular mechanisms by which PI3K/AKT signaling is activated but also suggest that targeting the LZTS2/PI3K/AKT signaling axis is a promising therapeutic strategy for radiosensitization of nasopharyngeal carcinoma.

MiR-126 overexpression inhibits high glucose-induced migration and tube formation of rhesus macaque choroid-retinal endothelial cells by obstructing VEGFA and PIK3R2

AIM

The aims of this study are to investigate the relative regulation between miR-126 and VEGF/PI3K/AKT signaling pathway in retinal vascular endothelial cells.

METHODS

Rhesus macaque choroid-retinal endothelial cell line (RF/6A) cells were cultured in high glucose to imitate the conditions occurring in DR. First, we detected the expression of miR-126, VEGFA and PIK3R2 in RF/6A cells on the condition of high glucose by q-PCR and western blot. Then, after addition of miR-126 mimics and miR-126 inhibitor, we investigated the function of miR-126 in RF/6A cells by scratch wound, Transwell migration and tube formation assays, and the effect of miR-126 on the expression of VEGFA, PIK3R2 and AKT. Moreover, bioinformatics analysis and luciferase array were used to confirm the direct or specific regulation of miR-126 to VEGFA or PIK3R2.

RESULTS

Here, first, we found that high glucose could induce the decrease of miR-126 and the increase of VEGFA and PIK3R2 in RF/6A. Then, by scratch wound, Transwell migration and tube formation assays, we found that miR-126 overexpression could inhibit the migration and sprouting of RF/6A cells induced by high glucose, while knockdown of miR-126 led to the opposite results. Moreover, overexpression of miR-126 inhibited the increased expression of VEGFA, PIK3R2, SDF-1α, VCAM-1, and SPRED1, and the activation of AKT1 induced by high glucose and miR-126 inhibitor caused the opposite results which were determined by q-PCR and western blot. In addition, by luciferase assay, we found that miR-126 could directly negatively regulate VEGFA and PIK3R2.

CONCLUSION

Our results suggest that miR-126 overexpression inhibits the migration and sprouting of RF/6A cells induced by high glucose which might possibly be by blocking VEGFA and PIK3R2 in the VEGF/PI3K/AKT signaling pathway.

Low-Dose Dihydrotestosterone Drives Metabolic Dysfunction via Cytosolic and Nuclear Hepatic Androgen Receptor Mechanisms

Androgen excess in women is associated with metabolic dysfunction (e.g., obesity, hyperinsulinemia, insulin resistance, and increased risk of type 2 diabetes) and reproductive dysfunction (e.g., polycystic ovaries, amenorrhea, dysregulated gonadotropin release, and infertility). We sought to identify the effects of androgen excess on glucose metabolic dysfunction and the specific mechanisms of action by which androgens are inducing pathology. We developed a mouse model that displayed pathophysiological serum androgen levels with normal body mass/composition to ensure that the phenotypes were directly from androgens and not an indirect consequence of obesity. We performed reproductive tests, metabolic tests, and hormonal assays. Livers were isolated and examined via molecular, biochemical, and histological analysis. Additionally, a low-dose dihydrotestosterone (DHT) cell model using H2.35 mouse hepatocytes was developed to study androgen effects on hepatic insulin signaling. DHT mice demonstrated impaired estrous cyclicity; few corpora lutea in the ovaries; glucose, insulin, and pyruvate intolerance; and lowered hepatic insulin action. Mechanistically, DHT increased hepatic androgen-receptor binding to phosphoinositide-3-kinase (PI3K)-p85, resulting in dissociation of PI3K-p85 from PI3K-p110, leading to reduced PI3K activity and decreased p-AKT and, thus, lowered insulin action. DHT increased gluconeogenesis via direct transcriptional regulation of gluconeogenic enzymes and coactivators. The hepatocyte model recapitulated the in vivo findings. The DHT-induced hepatocyte insulin resistance was reversed by the androgen-receptor antagonist, flutamide. These findings present a phenotype (i.e., impaired glucose tolerance and disrupted glucose metabolism) in a lean hyperandrogenemia model (low-dose DHT) and data to support 2 molecular mechanisms that help drive androgen-induced impaired glucose metabolism.

Hydrostatic Compress Force Enhances the Viability and Decreases the Apoptosis of Condylar Chondrocytes through Integrin-FAK-ERK/PI3K Pathway

Reduced mechanical stimuli in many pathological cases, such as hemimastication and limited masticatory movements, can significantly affect the metabolic activity of mandibular condylar chondrocytes and the growth of mandibles. However, the molecular mechanisms for these phenomena remain unclear. In this study, we hypothesized that integrin-focal adhesion kinase (FAK)-ERK (extracellular signal-regulated kinase)/PI3K (phosphatidylinositol-3-kinase) signaling pathway mediated the cellular response of condylar chondrocytes to mechanical loading. Primary condylar chondrocytes were exposed to hydrostatic compressive forces (HCFs) of different magnitudes (0, 50, 100, 150, 200, and 250 kPa) for 2 h. We measured the viability, morphology, and apoptosis of the chondrocytes with different treatments as well as the gene, protein expression, and phosphorylation of mechanosensitivity-related molecules, such as integrin α2, integrin α5, integrin β1, FAK, ERK, and PI3K. HCFs could significantly increase the viability and surface area of condylar chondrocytes and decrease their apoptosis in a dose-dependent manner. HCF of 250 kPa resulted in a 1.51 ± 0.02-fold increase of cell viability and reduced the ratio of apoptotic cells from 18.10% ± 0.56% to 7.30% ± 1.43%. HCFs could significantly enhance the mRNA and protein expression of integrin α2, integrin α5, and integrin β1 in a dose-dependent manner, but not ERK1, ERK2, or PI3K. Instead, HCF could significantly increase phosphorylation levels of FAK, ERK1/2, and PI3K in a dose-dependent manner. Cilengitide, the potent integrin inhibitor, could dose-dependently block such effects of HCFs. HCFs enhances the viability and decreases the apoptosis of condylar chondrocytes through the integrin-FAK-ERK/PI3K pathway.

p85α promotes nucleolin transcription and subsequently enhances EGFR mRNA stability and EGF-induced malignant cellular transformation

p85α is a regulatory subunit of phosphatidylinositol 3-kinase (PI3K) that is a key lipid enzyme for generating phosphatidylinositol 3, 4, 5-trisphosphate, and subsequently activates signaling that ultimately regulates cell cycle progression, cell growth, cytoskeletal changes, and cell migration. In addition to form a complex with the p110 catalytic subunit, p85α also exists as a monomeric form due to that there is a greater abundance of p85α than p110 in many cell types. Our previous studies have demonstrated that monomeric p85α exerts a pro-apoptotic role in UV response through induction of TNF-α gene expression in PI3K-independent manner. In current studies, we identified a novel biological function of p85α as a positive regulator of epidermal growth factor receptor (EGFR) expression and cell malignant transformation via nucleolin-dependent mechanism. Our results showed that p85α was crucial for EGFR and nucleolin expression and subsequently resulted in an increase of malignant cellular transformation by using both specific knockdown and deletion of p85α in its normal expressed cells. Mechanistic studies revealed that p85α upregulated EGFR protein expression mainly through stabilizing its mRNA, whereas nucleolin (NCL) was able to bind to egfr mRNA and increase its mRNA stability. Consistently, overexpression of NCL in p85α-/- cells restored EGFR mRNA stabilization, protein expression and cell malignant transformation. Moreover, we discovered that p85α upregulated NCL gene transcription via enhancing C-Jun activation. Collectively, our studies demonstrate a novel function of p85α as a positive regulator of EGFR mRNA stability and cell malignant transformation, providing a significant insight into the understanding of biomedical nature of p85α protein in mammalian cells and further supporting that p85α might be a potential target for cancer prevention and therapy.

A Cytosolic Multiprotein Complex Containing p85α Is Required for β-Catenin Activation in Colitis and Colitis-associated Cancer

Wnt/β-catenin signaling is required for crypt structure maintenance. We previously observed nuclear accumulation of Ser-552 phosphorylated β-catenin (pβ-Cat(Ser-552)) in intestinal epithelial cells (IEC) during colitis and colitis-associated cancer. Data here delineate a novel multiprotein cytosolic complex (MCC) involved in β-catenin signaling in the intestine. The MCC contains p85α, the class IA subunit of PI3K, along with β-catenin, 14-3-3ζ, Akt, and p110α. MCC levels in IEC increase in colitis and colitis-associated cancer patients. IEC-specific p85α-deficient (p85(ΔIEC)) mice develop more severe dextran sodium sulfate colitis due to delayed ulcer healing and reduced epithelial β-catenin activation. In colonic IEC, p85α deficiency did not alter PI3K signaling. In vitro shRNA depletion of individual complex members disrupts the MCC and reduces β-catenin signaling. Despite worse colitis, p85(ΔIEC) mice have reduced tumor burden after azoxymethane/dextran sodium sulfate treatment. Together the data indicate that the β-catenin MCC is needed for mucosal repair and carcinogenesis. This novel MCC may be an attractive therapeutic target in preventing cancer in colitis patients.

Molecules in medicine mini-review: isoforms of PI3K in biology and disease

The PI3K lipid kinases are involved in signal transduction and intracellular vesicular traffic, endowing these enzymes with multiple cellular functions and important roles in normal physiology and disease. In this mini-review, we aim to distill from the vast PI3K literature the key relevant concepts for successful targeting of this pathway in disease. Of the eight isoforms of PI3K, the class I PI3Ks have been implicated in the aetiology and maintenance of various diseases, most prominently cancer, overgrowth syndromes, inflammation and autoimmunity, with emerging potential roles in metabolic and cardiovascular disorders. The development of class I PI3K inhibitors, mainly for use in cancer and inflammation, is a very active area of drug development. In 2014, an inhibitor of the p110δ isoform of PI3K was approved for the treatment of specific human B cell malignancies. The key therapeutic indications of targeting each class I PI3K isoform are summarized and discussed.

Regulation of the PI3K pathway through a p85α monomer-homodimer equilibrium

The canonical action of the p85α regulatory subunit of phosphatidylinositol 3-kinase (PI3K) is to associate with the p110α catalytic subunit to allow stimuli-dependent activation of the PI3K pathway. We elucidate a p110α-independent role of homodimerized p85α in the positive regulation of PTEN stability and activity. p110α-free p85α homodimerizes via two intermolecular interactions (SH3:proline-rich region and BH:BH) to selectively bind unphosphorylated activated PTEN. As a consequence, homodimeric but not monomeric p85α suppresses the PI3K pathway by protecting PTEN from E3 ligase WWP2-mediated proteasomal degradation. Further, the p85α homodimer enhances the lipid phosphatase activity and membrane association of PTEN. Strikingly, we identified cancer patient-derived oncogenic p85α mutations that target the homodimerization or PTEN interaction surface. Collectively, our data suggest the equilibrium of p85α monomer-dimers regulates the PI3K pathway and disrupting this equilibrium could lead to disease development.

The Phosphoinositide 3-Kinase p110α Isoform Regulates Leukemia Inhibitory Factor Receptor Expression via c-Myc and miR-125b to Promote Cell Proliferation in Medulloblastoma

Medulloblastoma (MB) is the most common malignant brain tumor in childhood and represents the main cause of cancer-related death in this age group. The phosphoinositide 3-kinase (PI3K) pathway has been shown to play an important role in the regulation of medulloblastoma cell survival and proliferation, but the molecular mechanisms and downstream effectors underlying PI3K signaling still remain elusive. The impact of RNA interference (RNAi)-mediated silencing of PI3K isoforms p110α and p110δ on global gene expression was investigated by DNA microarray analysis in medulloblastoma cell lines. A subset of genes with selectively altered expression upon p110α silencing in comparison to silencing of the closely related p110δ isoform was revealed. Among these genes, the leukemia inhibitory factor receptor α (LIFR α) was validated as a novel p110α target in medulloblastoma. A network involving c-Myc and miR-125b was shown to be involved in the control of LIFRα expression downstream of p110α. Targeting the LIFRα by RNAi, or by using neutralizing reagents impaired medulloblastoma cell proliferation in vitro and induced a tumor volume reduction in vivo. An analysis of primary tumors revealed that LIFRα and p110α expression were elevated in the sonic hedgehog (SHH) subgroup of medulloblastoma, indicating its clinical relevance. Together, these data reveal a novel molecular signaling network, in which PI3K isoform p110α controls the expression of LIFRα via c-Myc and miR-125b to promote MB cell proliferation.

Phosphoinositide 3-kinase p110δ promotes lumen formation through the enhancement of apico-basal polarity and basal membrane organization

Signalling triggered by adhesion to the extracellular matrix plays a key role in the spatial orientation of epithelial polarity and formation of lumens in glandular tissues. Phosphoinositide 3-kinase signalling in particular is known to influence the polarization process during epithelial cell morphogenesis. Here, using Madin-Darby canine kidney epithelial cells grown in 3D culture, we show that the p110δ isoform of phosphoinositide 3-kinase co-localizes with focal adhesion proteins at the basal surface of polarized cells. Pharmacological, siRNA- or kinase-dead-mediated inhibition of p110δ impair the early stages of lumen formation, resulting in inverted polarized cysts, with no laminin or type IV collagen assembly at cell/extracellular matrix contacts. p110δ also regulates the organization of focal adhesions and membrane localization of dystroglycan. Thus, we uncover a previously unrecognized role for p110δ in epithelial cells in the orientation of the apico-basal axis and lumen formation.

Pancreatic cell plasticity and cancer initiation induced by oncogenic Kras is completely dependent on wild-type PI 3-kinase p110α

Increased PI 3-kinase (PI3K) signaling in pancreatic ductal adenocarcinoma (PDAC) correlates with poor prognosis, but the role of class I PI3K isoforms during its induction remains unclear. Using genetically engineered mice and pharmacological isoform-selective inhibitors, we found that the p110α PI3K isoform is a major signaling enzyme for PDAC development induced by a combination of genetic and nongenetic factors. Inactivation of this single isoform blocked the irreversible transition of exocrine acinar cells into pancreatic preneoplastic ductal lesions by oncogenic Kras and/or pancreatic injury. Hitting the other ubiquitous isoform, p110β, did not prevent preneoplastic lesion initiation. p110α signaling through small GTPase Rho and actin cytoskeleton controls the reprogramming of acinar cells and regulates cell morphology in vivo and in vitro. Finally, p110α was necessary for pancreatic ductal cancers to arise from Kras-induced preneoplastic lesions by increasing epithelial cell proliferation in the context of mutated p53. Here we identify an in vivo context in which p110α cellular output differs depending on the epithelial transformation stage and demonstrate that the PI3K p110α is required for PDAC induced by oncogenic Kras, the key driver mutation of PDAC. These data are critical for a better understanding of the development of this lethal disease that is currently without efficient treatment.

β2-Adrenergic receptor-dependent attenuation of hypoxic pulmonary vasoconstriction prevents progression of pulmonary arterial hypertension in intermittent hypoxic rats

In sleep apnea syndrome (SAS), intermittent hypoxia (IH) induces repeated episodes of hypoxic pulmonary vasoconstriction (HPV) during sleep, which presumably contribute to pulmonary arterial hypertension (PAH). However, the prevalence of PAH was low and severity is mostly mild in SAS patients, and mild or no right ventricular hypertrophy (RVH) was reported in IH-exposed animals. The question then arises as to why PAH is not a universal finding in SAS if repeated hypoxia of sufficient duration causes cycling HPV. In the present study, rats underwent IH at a rate of 3 min cycles of 4-21% O2 for 8 h/d for 6 w. Assessment of diameter changes in small pulmonary arteries in response to acute hypoxia and drugs were performed using synchrotron radiation microangiography on anesthetized rats. In IH-rats, neither PAH nor RVH was observed and HPV was strongly reversed. Nadolol (a hydrophilic β(1, 2)-blocker) augmented the attenuated HPV to almost the same level as that in N-rats, but atenolol (a hydrophilic β1-blocker) had no effect on the HPV in IH. These β-blockers had almost no effect on the HPV in N-rats. Chronic administration of nadolol during 6 weeks of IH exposure induced PAH and RVH in IH-rats, but did not in N-rats. Meanwhile, atenolol had no effect on morphometric and hemodynamic changes in N and IH-rats. Protein expression of the β1-adrenergic receptor (AR) was down-regulated while that of β2AR was preserved in pulmonary arteries of IH-rats. Phosphorylation of p85 (chief component of phosphoinositide 3-kinase (PI3K)), protein kinase B (Akt), and endothelial nitric oxide synthase (eNOS) were abrogated by chronic administration of nadolol in the lung tissue of IH-rats. We conclude that IH-derived activation of β2AR in the pulmonary arteries attenuates the HPV, thereby preventing progression of IH-induced PAH. This protective effect may depend on the β2AR-Gi mediated PI3K/Akt/eNOS signaling pathway.

A panel of overexpressed proteins for prognosis in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a common cancer with poor prognosis. In order to identify useful biomarkers for accurately classifying prognostic risks for ESCC patients, we examined the expression of six proteins by immunohistochemistry (IHC) in 590 paraffin-embedded ESCC samples. The candidate proteins include p53, EGFR, c-KIT, TIMP1 and PI3K-p110α reported to be altered in ESCC tissues as well as another important component of PI3K, PI3K-p85α. Of the six proteins tested, p53, EGFR, c-KIT, TIMP1 and PI3K-p85α were detected with high expression in 43.0%, 36.6%, 55.9%, 70.7% and 57.1% of tumors, respectively. Significant associations were found between high expression of PI3K-p85α, EGFR and p53 and poor prognosis (P = 0.00111; 0.00001; 0.00426). Applying these three proteins as an IHC panel could divide patients into different subgroups (P<0.000001). Multivariate cox regression analysis indicated that the three-protein panel was an independent prognostic factor with very high statistical significance (HR = 2.090, 95% CI: 1.621–2.696, P = 0.00000001). The data suggest that the three-protein panel of PI3K-p85α, EGFR and p53 is an important candidate biomarker for the prognosis of patients with ESCC.

A rapid cytoplasmic mechanism for PI3 kinase regulation by the nuclear thyroid hormone receptor, TRβ, and genetic evidence for its role in the maturation of mouse hippocampal synapses in vivo

Several rapid physiological effects of thyroid hormone on mammalian cells in vitro have been shown to be mediated by the phosphatidylinositol 3-kinase (PI3K), but the molecular mechanism of PI3K regulation by nuclear zinc finger receptor proteins for thyroid hormone and its relevance to brain development in vivo have not been elucidated. Here we show that, in the absence of hormone, the thyroid hormone receptor TRβ forms a cytoplasmic complex with the p85 subunit of PI3K and the Src family tyrosine kinase, Lyn, which depends on two canonical phosphotyrosine motifs in the second zinc finger of TRβ that are not conserved in TRα. When hormone is added, TRβ dissociates and moves to the nucleus, and phosphatidylinositol (3, 4, 5)-trisphosphate production goes up rapidly. Mutating either tyrosine to a phenylalanine prevents rapid signaling through PI3K but does not prevent the hormone-dependent transcription of genes with a thyroid hormone response element. When the rapid signaling mechanism was blocked chronically throughout development in mice by a targeted point mutation in both alleles of Thrb, circulating hormone levels, TRβ expression, and direct gene regulation by TRβ in the pituitary and liver were all unaffected. However, the mutation significantly impaired maturation and plasticity of the Schaffer collateral synapses on CA1 pyramidal neurons in the postnatal hippocampus. Thus, phosphotyrosine-dependent association of TRβ with PI3K provides a potential mechanism for integrating regulation of development and metabolism by thyroid hormone and receptor tyrosine kinases.

Anti-inflammatory actions of acanthoic acid-related diterpenes involve activation of the PI3K p110γ/δ subunits and inhibition of NF-κB

The effect of acanthoic acid analogs on the response to proinflammatory challenge was investigated. Some pimarane diterpenes are known activators of the LXRαβ nuclear receptors, but we show here that they also exert a rapid, potent, and selective activation of the p110γ and p110δ subunits of PI3K. Combination of these effects results in an important attenuation of the global transcriptional response to LPS in macrophages. PI3K/Akt activation leads to inhibition of the LPS-dependent stimulation of IKK/NF-κB and p38 and ERK MAPKs. Macrophages from LXRαβ-deficient mice exhibited an inhibition of these pathways similar to the corresponding wild-type cells. Silencing or inhibition of p110γ/δ suppressed the effect of these diterpenes (DTPs) on IKK/NF-κB and MAPKs signaling. Taken together, these data show a multitarget anti-inflammatory mechanism by these DTPs including a selective activation of PI3K isoenzymes.

Flexibility of PCNA-protein interface accommodates differential binding partners

The expanding roles of PCNA in functional assembly of DNA replication and repair complexes motivated investigation of the structural and dynamic properties guiding specificity of PCNA-protein interactions. A series of biochemical and computational analyses were combined to evaluate the PIP Box recognition features impacting complex formation. The results indicate subtle differences in topological and molecular descriptors distinguishing both affinity and stoichiometry of binding among PCNA-peptide complexes through cooperative effects. These features were validated using peptide mimics of p85α and Akt, two previously unreported PCNA binding partners. This study characterizes for the first time a reverse PIP Box interaction with PCNA. Small molecule ligand binding at the PIP Box interaction site confirmed the adaptive nature of the protein in dictating overall shape and implicates allosterism in transmitting biological effects.

Enhancement of morphological plasticity in hippocampal neurons by a physically modified saline via phosphatidylinositol-3 kinase

Increase of the density of dendritic spines and enhancement of synaptic transmission through ionotropic glutamate receptors are important events, leading to synaptic plasticity and eventually hippocampus-dependent spatial learning and memory formation. Here we have undertaken an innovative approach to upregulate hippocampal plasticity. RNS60 is a 0.9% saline solution containing charge-stabilized nanobubbles that are generated by subjecting normal saline to Taylor-Couette-Poiseuille (TCP) flow under elevated oxygen pressure. RNS60, but not NS (normal saline), PNS60 (saline containing a comparable level of oxygen without the TCP modification), or RNS10.3 (TCP-modified normal saline without excess oxygen), stimulated morphological plasticity and synaptic transmission via NMDA- and AMPA-sensitive calcium influx in cultured mouse hippocampal neurons. Using mRNA-based targeted gene array, real-time PCR, immunoblot, and immunofluorescence analyses, we further demonstrate that RNS60 stimulated the expression of many plasticity-associated genes in cultured hippocampal neurons. Activation of type IA, but not type IB, phosphatidylinositol-3 (PI-3) kinase by RNS60 together with abrogation of RNS60-mediated upregulation of plasticity-related proteins (NR2A and GluR1) and increase in spine density, neuronal size, and calcium influx by LY294002, a specific inhibitor of PI-3 kinase, suggest that RNS60 upregulates hippocampal plasticity via activation of PI-3 kinase. Finally, in the 5XFAD transgenic model of Alzheimer's disease (AD), RNS60 treatment upregulated expression of plasticity-related proteins PSD95 and NR2A and increased AMPA- and NMDA-dependent hippocampal calcium influx. These results describe a novel property of RNS60 in stimulating hippocampal plasticity, which may help AD and other dementias.

[The effects of ceruloplasmin in PI3K/PTEN cell signaling pathway change induced by silica]

OBJECTIVE

To investigate the roles of ceruloplasmin (Cp) in PI3K/PTEN cell signaling pathway change in human embryonic lung fibroblasts (HELFs) induced by silica.

METHODS

HELFs transfected with pGenesil1.1 plasmid and pGenesil1.1 with PTEN shRNA (PT) plasmid were successfully established. 100 µg/ml silica and different concentrations of Cp (10, 20, 30 µg/ml) were used in this experiment and Cp were treated cells after exposed to silica for 1h. Three different cell lines (including HELFs, PT and cells were transfected with p85 dominant negative mutant plasmid (DN-p85)) were divided into control groups, silica groups and silica+different concentrations of Cp groups. MTT assay was used to detect the effects of Cp on silica-induced cell proliferation after inhibiting PTEN and p85. When suppressing the expression of PTEN and p85, western blot assay was performed to detect the levels of p85, p110, AKT308, AKT473 and ERK, JNK and their phosphorylated levels.

RESULTS

After inhibition of PTEN, the high levels of p85 induced by 100 µg/ml silica with 30 µg/ml Cp were markedly decreased (P<0.05). When suppressing p85, the increased cell proliferation was not observed. And the high levels of AKT308, AKT473, ERK and phosphorylated JNK and ERK stimulated by 100 µg/ml silica with 30 µg/ml Cp were decrease (P < 0.05).

CONCLUSION

Cp could further strengthened silica-induced cell proliferation by PI3K/AKT/MAPK cell signaling pathway, of which the level of p85 was regulated by PTEN.