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1.
Nat Struct Mol Biol ; 29(3): 218-228, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35256802

RESUMO

Phosphatidylinositol 3-kinase type 2α (PI3KC2α) is an essential member of the structurally unresolved class II PI3K family with crucial functions in lipid signaling, endocytosis, angiogenesis, viral replication, platelet formation and a role in mitosis. The molecular basis of these activities of PI3KC2α is poorly understood. Here, we report high-resolution crystal structures as well as a 4.4-Å cryogenic-electron microscopic (cryo-EM) structure of PI3KC2α in active and inactive conformations. We unravel a coincident mechanism of lipid-induced activation of PI3KC2α at membranes that involves large-scale repositioning of its Ras-binding and lipid-binding distal Phox-homology and C-C2 domains, and can serve as a model for the entire class II PI3K family. Moreover, we describe a PI3KC2α-specific helical bundle domain that underlies its scaffolding function at the mitotic spindle. Our results advance our understanding of PI3K biology and pave the way for the development of specific inhibitors of class II PI3K function with wide applications in biomedicine.


Assuntos
Fosfatidilinositol 3-Quinase , Fosfatidilinositol 3-Quinases , Endocitose , Lipídeos , Fosfatidilinositol 3-Quinases/metabolismo , Transdução de Sinais
2.
Adv Sci (Weinh) ; 9(9): e2103249, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35098698

RESUMO

Breast cancer is the most prevalent cancer and a major cause of death in women worldwide. Although early diagnosis and therapeutic intervention significantly improve patient survival rate, metastasis still accounts for most deaths. Here it is reported that, in a cohort of more than 2000 patients with breast cancer, overexpression of PI3KC2α occurs in 52% of cases and correlates with high tumor grade as well as increased probability of distant metastatic events, irrespective of the subtype. Mechanistically, it is demonstrated that PI3KC2α synthetizes a pool of PI(3,4)P2 at focal adhesions that lowers their stability and directs breast cancer cell migration, invasion, and metastasis. PI(3,4)P2 locally produced by PI3KC2α at focal adhesions recruits the Ras GTPase activating protein 3 (RASA3), which inactivates R-RAS, leading to increased focal adhesion turnover, migration, and invasion both in vitro and in vivo. Proof-of-concept is eventually provided that inhibiting PI3KC2α or lowering RASA3 activity at focal adhesions significantly reduces the metastatic burden in PI3KC2α-overexpressing breast cancer, thereby suggesting a novel strategy for anti-breast cancer therapy.


Assuntos
Neoplasias da Mama , Adesão Celular/fisiologia , Feminino , Adesões Focais/metabolismo , Adesões Focais/patologia , Proteínas Ativadoras de GTPase/metabolismo , Humanos , Fosfatidilinositóis/metabolismo
3.
Science ; 374(6573): eabk0410, 2021 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-34882480

RESUMO

Cytokinetic membrane abscission is a spatially and temporally regulated process that requires ESCRT (endosomal sorting complexes required for transport)­dependent control of membrane remodeling at the midbody, a subcellular organelle that defines the cleavage site. Alteration of ESCRT function can lead to cataract, but the underlying mechanism and its relation to cytokinesis are unclear. We found a lens-specific cytokinetic process that required PI3K-C2α (phosphatidylinositol-4-phosphate 3-kinase catalytic subunit type 2α), its lipid product PI(3,4)P2 (phosphatidylinositol 3,4-bisphosphate), and the PI(3,4)P2­binding ESCRT-II subunit VPS36 (vacuolar protein-sorting-associated protein 36). Loss of each of these components led to impaired cytokinesis, triggering premature senescence in the lens of fish, mice, and humans. Thus, an evolutionarily conserved pathway underlies the cell type­specific control of cytokinesis that helps to prevent early onset cataract by protecting from senescence.


Assuntos
Catarata/patologia , Senescência Celular , Citocinese , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Cristalino/citologia , Fosfatidilinositol 3-Quinases/metabolismo , Fosfatidilinositóis/metabolismo , Senilidade Prematura , Animais , Evolução Biológica , Proteínas de Ligação ao Cálcio/metabolismo , Catarata/metabolismo , Proteínas de Ciclo Celular/metabolismo , Linhagem Celular , Humanos , Cristalino/crescimento & desenvolvimento , Cristalino/metabolismo , Camundongos , Mutação , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 4,5-Difosfato/metabolismo , Tubulina (Proteína)/metabolismo , Peixe-Zebra , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismo
4.
Cancers (Basel) ; 13(14)2021 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-34298731

RESUMO

Breast cancer is the most frequently diagnosed cancer and the primary cause of cancer death in women worldwide. Although early diagnosis and cancer growth inhibition has significantly improved breast cancer survival rate over the years, there is a current need to develop more effective systemic treatments to prevent metastasis. One of the most commonly altered pathways driving breast cancer cell growth, survival, and motility is the PI3K/AKT/mTOR signaling cascade. In the past 30 years, a great surge of inhibitors targeting these key players has been developed at a rapid pace, leading to effective preclinical studies for cancer therapeutics. However, the central role of PI3K/AKT/mTOR signaling varies among diverse biological processes, suggesting the need for more specific and sophisticated strategies for their use in cancer therapy. In this review, we provide a perspective on the role of the PI3K signaling pathway and the most recently developed PI3K-targeting breast cancer therapies.

5.
Front Oncol ; 10: 360, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32296634

RESUMO

The phosphatidylinositide 3 kinases (PI3Ks) and their downstream mediators AKT and mammalian target of rapamycin (mTOR) are central regulators of glycolysis, cancer metabolism, and cancer cell proliferation. At the molecular level, PI3K signaling involves the generation of the second messenger lipids phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3] and phosphatidylinositol 3,4-bisphosphate [PI(3,4)P2]. There is increasing evidence that PI(3,4)P2 is not only the waste product for the removal of PI(3,4,5)P3 but can also act as a signaling molecule. The selective cellular functions for PI(3,4)P2 independent of PI(3,4,5)P3 have been recently described, including clathrin-mediated endocytosis and mTOR regulation. However, the specific spatiotemporal dynamics and signaling role of PI3K minor lipid messenger PI(3,4)P2 are not well-understood. This review aims at highlighting the biological functions of this lipid downstream of phosphoinositide kinases and phosphatases and its implication in cancer metabolism.

6.
Adv Biol Regul ; 75: 100693, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-32008962

RESUMO

Phosphoinositides (PI) are key players in many trafficking and signaling pathways. Recent advances regarding the synthesis, location and functions of these lipids have improved our understanding of how and when these lipids are generated and what their roles are in physiology and disease. In particular, PI play a central role in the regulation of cell proliferation and metabolism. Here, we will review recent advances in our understanding of PI function, regulation, and importance in different aspects of proliferation and energy metabolism.


Assuntos
Metabolismo Energético , Fosfatidilinositóis/metabolismo , Transdução de Sinais , Animais , Humanos , Fosfatidilinositóis/genética , Transporte Proteico
7.
J Exp Clin Cancer Res ; 38(1): 472, 2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31752944

RESUMO

BACKGROUND: Alteration of signalling pathways regulating cell cycle progression is a common feature of cancer cells. Several drugs targeting distinct phases of the cell cycle have been developed but the inability of many of them to discriminate between normal and cancer cells has strongly limited their clinical potential because of their reduced efficacy at the concentrations used to limit adverse side effects. Mechanisms of resistance have also been described, further affecting their efficacy. Identification of novel targets that can potentiate the effect of these drugs or overcome drug resistance can provide a useful strategy to exploit the anti-cancer properties of these agents to their fullest. METHODS: The class II PI3K isoform PI3K-C2ß was downregulated in prostate cancer PC3 cells and cervical cancer HeLa cells using selective siRNAs and the effect on cell growth was determined in the absence or presence of the microtubule-stabilizing agent/anti-cancer drug docetaxel. Mitosis progression was monitored by time-lapse microscopy. Clonogenic assays were performed to determine the ability of PC3 and HeLa cells to form colonies upon PI3K-C2ß downregulation in the absence or presence of docetaxel. Cell multi-nucleation was assessed by immunofluorescence. Tumour growth in vivo was assessed using a xenograft model of PC3 cells upon PI3K-C2ß downregulation and in combination with docetaxel. RESULTS: Downregulation of PI3K-C2ß delays mitosis progression in PC3 and HeLa cells, resulting in reduced ability to form colonies in clonogenic assays in vitro. Compared to control cells, PC3 cells lacking PI3K-C2ß form smaller and more compact colonies in vitro and they form tumours more slowly in vivo in the first weeks after cells implant. Stable and transient PI3K-C2ß downregulation potentiates the effect of low concentrations of docetaxel on cancer cell growth. Combination of PI3K-C2ß downregulation and docetaxel almost completely prevents colonies formation in clonogenic assays in vitro and strongly inhibits tumour growth in vivo. CONCLUSIONS: These data reveal a novel role for the class II PI3K PI3K-C2ß during mitosis progression. Furthermore, data indicate that blockade of PI3K-C2ß might represent a novel strategy to potentiate the effect of docetaxel on cancer cell growth.


Assuntos
Classe II de Fosfatidilinositol 3-Quinases/metabolismo , Docetaxel/farmacologia , Neoplasias da Próstata/tratamento farmacológico , Neoplasias da Próstata/enzimologia , Neoplasias do Colo do Útero/tratamento farmacológico , Neoplasias do Colo do Útero/enzimologia , Animais , Antineoplásicos/farmacologia , Divisão Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Regulação para Baixo , Feminino , Células HeLa , Humanos , Masculino , Camundongos Nus , Células PC-3 , Neoplasias da Próstata/patologia , Distribuição Aleatória , Transfecção , Neoplasias do Colo do Útero/patologia , Ensaios Antitumorais Modelo de Xenoenxerto
8.
PLoS Genet ; 15(4): e1008088, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-31034465

RESUMO

PIK3C2A is a class II member of the phosphoinositide 3-kinase (PI3K) family that catalyzes the phosphorylation of phosphatidylinositol (PI) into PI(3)P and the phosphorylation of PI(4)P into PI(3,4)P2. At the cellular level, PIK3C2A is critical for the formation of cilia and for receptor mediated endocytosis, among other biological functions. We identified homozygous loss-of-function mutations in PIK3C2A in children from three independent consanguineous families with short stature, coarse facial features, cataracts with secondary glaucoma, multiple skeletal abnormalities, neurological manifestations, among other findings. Cellular studies of patient-derived fibroblasts found that they lacked PIK3C2A protein, had impaired cilia formation and function, and demonstrated reduced proliferative capacity. Collectively, the genetic and molecular data implicate mutations in PIK3C2A in a new Mendelian disorder of PI metabolism, thereby shedding light on the critical role of a class II PI3K in growth, vision, skeletal formation and neurological development. In particular, the considerable phenotypic overlap, yet distinct features, between this syndrome and Lowe's syndrome, which is caused by mutations in the PI-5-phosphatase OCRL, highlight the key role of PI metabolizing enzymes in specific developmental processes and demonstrate the unique non-redundant functions of each enzyme. This discovery expands what is known about disorders of PI metabolism and helps unravel the role of PIK3C2A and class II PI3Ks in health and disease.


Assuntos
Doenças do Desenvolvimento Ósseo/genética , Catarata/genética , Transtornos da Motilidade Ciliar/genética , Nanismo/genética , Mutação , Fosfatidilinositol 3-Quinases/genética , Adolescente , Adulto , Criança , Consanguinidade , Feminino , Fibroblastos/metabolismo , Humanos , Masculino , Linhagem , Fenótipo , Adulto Jovem
9.
Biochim Biophys Acta Rev Cancer ; 1871(2): 361-366, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30946868

RESUMO

The key role of phosphoinositide 3-kinase (PI3K) pathway in different cellular processes and several disorders, together with the presence of targetable proteins, opened the way to promising studies for the development of small molecule inhibitors. Despite the high expectation, the shift of PI3K inhibitors to the clinic met several limitations due to the emergence of dose-limiting, on-target adverse effects. In this review, we will summarize the main issues and recent advances in PI3K inhibitors clinical trials. The effort to develop isoform-specific inhibitors, together with novel therapeutic strategies aimed at reducing the toxicity and adverse effects, opened a new promising era for PI3K inhibitors. In addition, we will focus on the recent emergence of class II and III PI3K inhibitors, which helped to define their class I non-redundant role.


Assuntos
Neoplasias/enzimologia , Inibidores de Fosfoinositídeo-3 Quinase , Inibidores de Proteínas Quinases/farmacologia , Transdução de Sinais/fisiologia , Animais , Antineoplásicos/farmacologia , Humanos , Terapia de Alvo Molecular/efeitos adversos , Terapia de Alvo Molecular/métodos , Neoplasias/tratamento farmacológico
10.
Trends Cell Biol ; 29(4): 339-359, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30691999

RESUMO

The phosphoinositide 3-kinases (PI3Ks) are a family of lipid kinases that phosphorylate inositol phospholipids, thereby controlling membrane lipid composition and regulating a wide range of intracellular processes, including vesicular trafficking and signal transduction. Despite the vast knowledge on class I PI3Ks, recent studies are only now revealing the importance of class II PI3Ks in cell proliferation, survival, and migration. Increasing evidence suggests that the three class II PI3Ks isoforms (PI3K-C2α, PI3K-C2ß, and PI3K-C2γ) have distinct and non-overlapping cellular roles. Here, we focus on the cellular functions of class II PI3Ks in different cell systems and underline the emerging importance of these enzymes in various physiological and pathological contexts.


Assuntos
Células/citologia , Células/enzimologia , Classe II de Fosfatidilinositol 3-Quinases/metabolismo , Doenças Metabólicas/enzimologia , Neoplasias/enzimologia , Animais , Células/patologia , Humanos , Doenças Metabólicas/patologia , Neoplasias/patologia , Transdução de Sinais
11.
Mol Cell ; 71(2): 343-351.e4, 2018 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-30029007

RESUMO

Class II phosphoinositide 3-kinases (PI3K-C2) are large multidomain enzymes that control cellular functions ranging from membrane dynamics to cell signaling via synthesis of 3'-phosphorylated phosphoinositides. Activity of the alpha isoform (PI3K-C2α) is associated with endocytosis, angiogenesis, and glucose metabolism. How PI3K-C2α activity is controlled at sites of endocytosis remains largely enigmatic. Here we show that the lipid-binding PX-C2 module unique to class II PI3Ks autoinhibits kinase activity in solution but is essential for full enzymatic activity at PtdIns(4,5)P2-rich membranes. Using HDX-MS, we show that the PX-C2 module folds back onto the kinase domain, inhibiting its basal activity. Destabilization of this intramolecular contact increases PI3K-C2α activity in vitro and in cells, leading to accumulation of its lipid product, increased recruitment of the endocytic effector SNX9, and facilitated endocytosis. Our studies uncover a regulatory mechanism in which coincident binding of phosphoinositide substrate and cofactor selectively activate PI3K-C2α at sites of endocytosis.


Assuntos
Classe II de Fosfatidilinositol 3-Quinases/metabolismo , Classe II de Fosfatidilinositol 3-Quinases/fisiologia , Fosfatidilinositol 3-Quinases/fisiologia , Animais , Domínios C2/fisiologia , Células COS , Chlorocebus aethiops , Classe I de Fosfatidilinositol 3-Quinases/metabolismo , Classe I de Fosfatidilinositol 3-Quinases/fisiologia , Clatrina/fisiologia , Endocitose/fisiologia , Células HEK293 , Homeostase , Humanos , Lipídeos/fisiologia , Espectrometria de Massas , Fosfatidilinositol 3-Quinases/metabolismo , Fosforilação , Ligação Proteica , Domínios Proteicos , Transdução de Sinais
12.
Cancer Cell ; 32(4): 444-459.e7, 2017 10 09.
Artigo em Inglês | MEDLINE | ID: mdl-29017056

RESUMO

Proper organization of the mitotic spindle is key to genetic stability, but molecular components of inter-microtubule bridges that crosslink kinetochore fibers (K-fibers) are still largely unknown. Here we identify a kinase-independent function of class II phosphoinositide 3-OH kinase α (PI3K-C2α) acting as limiting scaffold protein organizing clathrin and TACC3 complex crosslinking K-fibers. Downregulation of PI3K-C2α causes spindle alterations, delayed anaphase onset, and aneuploidy, indicating that PI3K-C2α expression is required for genomic stability. Reduced abundance of PI3K-C2α in breast cancer models initially impairs tumor growth but later leads to the convergent evolution of fast-growing clones with mitotic checkpoint defects. As a consequence of altered spindle, loss of PI3K-C2α increases sensitivity to taxane-based therapy in pre-clinical models and in neoadjuvant settings.


Assuntos
Neoplasias da Mama/patologia , Instabilidade Genômica , Fosfatidilinositol 3-Quinases/fisiologia , Fuso Acromático/fisiologia , Animais , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/genética , Proteínas de Ciclo Celular/fisiologia , Proliferação de Células , Humanos , Células MCF-7 , Proteínas Mad2/fisiologia , Camundongos , Proteínas Associadas aos Microtúbulos/fisiologia , Proteínas Nucleares/fisiologia , Taxoides/uso terapêutico
13.
J Cell Biochem ; 118(11): 3561-3568, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28419521

RESUMO

Cytokinetic abscission involves the fine and regulated recruitment of membrane remodeling proteins that participate in the abscission of the intracellular bridge that connects the two dividing cells. This essential process is mediated by the concomitant activity of the endosomal sorting complex required for transport (ESCRT) and the vesicular trafficking directed to the midbody. Phosphoinositides (PtdIns), produced at plasma membrane, and endosomes, act as molecular intermediates by recruiting effector proteins involved in multiple cellular processes, such as intracellular signaling, endo- and exo-cytosis, and membrane remodeling events. Emerging evidences suggest that PtdIns have an active role in recruiting key elements that control the stability and the remodeling of the cytoskeleton from the furrow ingression to the abscission, at the end of cytokinesis. Accordingly, a possible concomitant and coordinated activity between PtdIns production and ESCRT machinery assembly could also exist and recent findings are pointing the attention on poorly understood ESCRT subunits potentially able to associate with PtdIns rich membranes. Although further studies are required to link PtdIns to ESCRT machinery during abscission, this might represent a promising field of study. J. Cell. Biochem. 118: 3561-3568, 2017. © 2017 Wiley Periodicals, Inc.


Assuntos
Membrana Celular/metabolismo , Citocinese/fisiologia , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Fosfatidilinositóis/metabolismo , Animais , Humanos
14.
J Am Soc Nephrol ; 27(4): 1135-44, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26271513

RESUMO

Signaling from the primary cilium regulates kidney tubule development and cyst formation. However, the mechanism controlling targeting of ciliary components necessary for cilium morphogenesis and signaling is largely unknown. Here, we studied the function of class II phosphoinositide 3-kinase-C2α (PI3K-C2α) in renal tubule-derived inner medullary collecting duct 3 cells and show that PI3K-C2α resides at the recycling endosome compartment in proximity to the primary cilium base. In this subcellular location, PI3K-C2α controlled the activation of Rab8, a key mediator of cargo protein targeting to the primary cilium. Consistently, partial reduction of PI3K-C2α was sufficient to impair elongation of the cilium and the ciliary transport of polycystin-2, as well as to alter proliferation signals linked to polycystin activity. In agreement, heterozygous deletion of PI3K-C2α in mice induced cilium elongation defects in kidney tubules and predisposed animals to cyst development, either in genetic models of polycystin-1/2 reduction or in response to ischemia/reperfusion-induced renal damage. These results indicate that PI3K-C2α is required for the transport of ciliary components such as polycystin-2, and partial loss of this enzyme is sufficient to exacerbate the pathogenesis of cystic kidney disease.


Assuntos
Cílios/fisiologia , Classe II de Fosfatidilinositol 3-Quinases/fisiologia , Doenças Renais Císticas , Canais de Cátion TRPP/fisiologia , Animais , Doenças Renais Císticas/etiologia , Masculino , Camundongos , Transdução de Sinais
15.
Cancer Discov ; 5(7): 740-51, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25883022

RESUMO

UNLABELLED: The phosphatases PTEN and INPP4B have been proposed to act as tumor suppressors by antagonizing PI3K-AKT signaling and are frequently dysregulated in human cancer. Although PTEN has been extensively studied, little is known about the underlying mechanisms by which INPP4B exerts its tumor-suppressive function and its role in tumorigenesis in vivo. Here, we show that a partial or complete loss of Inpp4b morphs benign thyroid adenoma lesions in Pten heterozygous mice into lethal and metastatic follicular-like thyroid cancer (FTC). Importantly, analyses of human thyroid cancer cell lines and specimens reveal INPP4B downregulation in FTC. Mechanistically, we find that INPP4B, but not PTEN, is enriched in the early endosomes of thyroid cancer cells, where it selectively inhibits AKT2 activation and in turn tumor proliferation and anchorage-independent growth. We therefore identify INPP4B as a novel tumor suppressor in FTC oncogenesis and metastasis through localized regulation of the PI3K-AKT pathway at the endosomes. SIGNIFICANCE: Although both PTEN and INPP4B can inhibit PI3K-AKT signaling through their lipid phosphatase activities, here we demonstrate lack of an epistatic relationship between the two tumor suppressors. Instead, the qualitative regulation of PI3K-AKT2 signaling by INPP4B provides a mechanism for their cooperation in suppressing thyroid tumorigenesis and metastasis.


Assuntos
Adenocarcinoma Folicular/patologia , Fosfatidilinositol 3-Quinases/metabolismo , Monoéster Fosfórico Hidrolases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Neoplasias da Glândula Tireoide/patologia , Adenocarcinoma Folicular/genética , Animais , Linhagem Celular Tumoral , Endossomos/metabolismo , Regulação Neoplásica da Expressão Gênica , Técnicas de Inativação de Genes , Humanos , Camundongos , Metástase Neoplásica , PTEN Fosfo-Hidrolase/metabolismo , Monoéster Fosfórico Hidrolases/genética , Transdução de Sinais , Neoplasias da Glândula Tireoide/genética
16.
Methods Enzymol ; 543: 115-40, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24924130

RESUMO

Phosphoinositide-3-kinase (PI3K) signaling has been implicated in a panoply of cellular responses including survival, proliferation, protein synthesis, migration, and vesicular trafficking. In addition, alterations in the enzymatic activity of PI3Ks have been involved in the pathogenesis of multiple diseases, ranging from cancer to chronic inflammation. The emerging interest in PI3K as a pharmacological target has prompted the development of several molecules with inhibitory activity. In this context, the quantification of the second messenger generated by PI3Ks, phosphoinositide-3-phosphate, offers an opportunity to directly test variations in the lipid kinase activity of PI3K in physiological as well as pathological conditions. Here, we will describe common methods to measure the lipid kinase activity of PI3K in vitro and new techniques to follow the production of phosphoinositide-3-phosphate in vivo. These methods are relevant to study the alterations of the PI3K systems at the interface between signaling and oncometabolism.


Assuntos
Fosfatidilinositol 3-Quinases/metabolismo , Animais , Cromatografia em Camada Delgada , Inibidores Enzimáticos/farmacologia , Humanos , Imunoprecipitação , Camundongos , Células NIH 3T3 , Inibidores de Fosfoinositídeo-3 Quinase
17.
Ann Med ; 46(6): 372-83, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24897931

RESUMO

Despite development of novel agents targeting oncogenic pathways, matching targeted therapies to the genetic status of individual tumors is proving to be a daunting task for clinicians. To improve the clinical efficacy and to reduce the toxic side effects of treatments, a deep characterization of genetic alterations in different tumors is required. The mutational profile often evidences a gain of function or hyperactivity of phosphoinositide 3-kinases (PI3Ks) in tumors. These enzymes are activated downstream tyrosine kinase receptors (RTKs) and/or G proteins coupled receptors (GPCRs) and, via AKT, are able to induce mammalian target of rapamycin (mTOR) stimulation. Here, we elucidate the impact of class I (p110α, ß, γ, and δ) catalytic subunit mutations on AKT-mediated cellular processes that control crucial mechanisms in tumor development. Moreover, the interrelation of PI3K signaling with mTOR, ERK, and RAS pathways will be discussed, exploiting the potential benefits of PI3K signaling inhibitors in clinical use.


Assuntos
Neoplasias/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais/fisiologia , Animais , Humanos , Neoplasias/genética , Neoplasias/fisiopatologia , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/fisiologia , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/fisiologia
18.
Dev Cell ; 28(6): 647-58, 2014 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-24697898

RESUMO

Multiple phosphatidylinositol (PtdIns) 3-kinases (PI3Ks) can produce PtdIns3P to control endocytic trafficking, but whether enzyme specialization occurs in defined subcellular locations is unclear. Here, we report that PI3K-C2α is enriched in the pericentriolar recycling endocytic compartment (PRE) at the base of the primary cilium, where it regulates production of a specific pool of PtdIns3P. Loss of PI3K-C2α-derived PtdIns3P leads to mislocalization of PRE markers such as TfR and Rab11, reduces Rab11 activation, and blocks accumulation of Rab8 at the primary cilium. These changes in turn cause defects in primary cilium elongation, Smo ciliary translocation, and Sonic Hedgehog (Shh) signaling and ultimately impair embryonic development. Selective reconstitution of PtdIns3P levels in cells lacking PI3K-C2α rescues Rab11 activation, primary cilium length, and Shh pathway induction. Thus, PI3K-C2α regulates the formation of a PtdIns3P pool at the PRE required for Rab11 and Shh pathway activation.


Assuntos
Movimento Celular/fisiologia , Cílios/fisiologia , Endossomos/metabolismo , Fosfatidilinositol 3-Quinases/fisiologia , Fosfatos de Fosfatidilinositol/metabolismo , Proteínas rab de Ligação ao GTP/metabolismo , Animais , Células Cultivadas , Embrião de Mamíferos/citologia , Embrião de Mamíferos/metabolismo , Feminino , Fibroblastos/citologia , Fibroblastos/metabolismo , Immunoblotting , Imunoprecipitação , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Inibidores de Fosfoinositídeo-3 Quinase , Transporte Proteico , RNA Interferente Pequeno/genética , Receptores Acoplados a Proteínas G/metabolismo , Receptores da Transferrina/metabolismo , Transdução de Sinais , Receptor Smoothened
19.
Nature ; 499(7457): 233-7, 2013 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-23823722

RESUMO

Phosphoinositides serve crucial roles in cell physiology, ranging from cell signalling to membrane traffic. Among the seven eukaryotic phosphoinositides the best studied species is phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2), which is concentrated at the plasma membrane where, among other functions, it is required for the nucleation of endocytic clathrin-coated pits. No phosphatidylinositol other than PI(4,5)P2 has been implicated in clathrin-mediated endocytosis, whereas the subsequent endosomal stages of the endocytic pathway are dominated by phosphatidylinositol-3-phosphates(PI(3)P). How phosphatidylinositol conversion from PI(4,5)P2-positive endocytic intermediates to PI(3)P-containing endosomes is achieved is unclear. Here we show that formation of phosphatidylinositol-3,4-bisphosphate (PI(3,4)P2) by class II phosphatidylinositol-3-kinase C2α (PI(3)K C2α) spatiotemporally controls clathrin-mediated endocytosis. Depletion of PI(3,4)P2 or PI(3)K C2α impairs the maturation of late-stage clathrin-coated pits before fission. Timed formation of PI(3,4)P2 by PI(3)K C2α is required for selective enrichment of the BAR domain protein SNX9 at late-stage endocytic intermediates. These findings provide a mechanistic framework for the role of PI(3,4)P2 in endocytosis and unravel a novel discrete function of PI(3,4)P2 in a central cell physiological process.


Assuntos
Endocitose , Fosfatos de Fosfatidilinositol/metabolismo , Sequência de Aminoácidos , Animais , Células COS , Chlorocebus aethiops , Classe II de Fosfatidilinositol 3-Quinases/metabolismo , Vesículas Revestidas por Clatrina/metabolismo , Células HEK293 , Células HeLa , Humanos , Dados de Sequência Molecular , Monoéster Fosfórico Hidrolases/metabolismo , Nexinas de Classificação/metabolismo , Fatores de Tempo
20.
Front Oncol ; 3: 108, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23658859

RESUMO

The phosphatidylinositol 3-kinase (PI3K) signaling pathway regulates several cellular processes and it's one of the most frequently deregulated pathway in human tumors. Given its prominent role in cancer, there is great interest in the development of inhibitors able to target several members of PI3K signaling pathway in clinical trials. These drug candidates include PI3K inhibitors, both pan- and isoform-specific inhibitors, AKT, mTOR, and dual PI3K/mTOR inhibitors. As novel compounds progress into clinical trials, it's becoming urgent to identify and select patient population that most likely benefit from PI3K inhibition. In this review we will discuss individual PIK3CA mutations as predictors of sensitivity and resistance to targeted therapies, leading to use of novel PI3K/mTOR/AKT inhibitors to a more "personalized" treatment.

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