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The placenta is essential for embryonic development, in part by mediating nutrient transfer from mother to embryo. Placental insufficiency is the most common cause of intrauterine growth restriction which has long-term health consequences lasting into adulthood. p110β is a class IA phosphoinositide 3-kinase (PI3K) catalytic subunit, a family of lipid kinases which are critical regulators of adult metabolism, immunity and embryonic and placental development. However, unlike the other class IA PI3K isoforms, the in vivo functions of p110β remain unclear. While homozygous p110β kinase-dead mice are mostly embryonically lethal, some survive into adulthood with no apparent phenotypes, other than reduced fertility. The mechanism(s) underlying this embryonic lethality remain unclear. Therefore, we performed an in-depth characterisation of p110β kinase-dead embryos, revealing a previously unrecognised role for p110β in controlling the expression of system A amino acid transporters. We show that homozygous p110β kinase-dead embryos are phenotypically normal, but growth-restricted and exhibit placental insufficiency. The placenta is small with a reduced nutrient storing junctional zone and downregulation of the system A amino acid transporters, required for maternal-to-embryo amino acid transfer. These data suggest defective amino acid transfer drives embryonic growth restriction and partial lethality of p110β kinase-dead embryos. This predominantly embryonic p110β phenotype is consistent with the notion that system A amino acid transporters are more critical during development than in adult physiology. The greater significance of p110β in development than in adult homeostasis may also help explain why p110β inhibitors, compared to inhibitors of other PI3K isoforms, are well-tolerated in adults.

TLR4 signaling shifts from plasma membrane TIRAP-MyD88–mediated pathways to endosomal TRAM-TRIF–mediated signaling. Vanhaesebroeck and colleagues show that the kinase PI(3)K p110δ is required for TLR4 internalization and degradation of TIRAP. Lipopolysaccharide activates plasma-membrane signaling and endosomal signaling by Toll-like receptor 4 (TLR4) through the TIRAP-MyD88 and TRAM-TRIF adaptor complexes, respectively, but it is unclear how the signaling switch between these cell compartments is coordinated. In dendritic cells, we found that the p110δ isoform of phosphatidylinositol-3-OH kinase (PI(3)K) induced internalization of TLR4 and dissociation of TIRAP from the plasma membrane, followed by calpain-mediated degradation of TIRAP. Accordingly, inactivation of p110δ prolonged TIRAP-mediated signaling from the plasma membrane, which augmented proinflammatory cytokine production while decreasing TRAM-dependent endosomal signaling that generated anti-inflammatory cytokines (interleukin 10 and interferon-β). In line with that altered signaling output, p110δ-deficient mice showed enhanced endotoxin-induced death. Thus, by controlling the 'topology' of TLR4 signaling complexes, p110δ balances overall homeostasis in the TLR4 pathway.

Mutations in PIK3CA are very frequent in cancer and lead to sustained PI3K pathway activation. The impact of acute expression of mutant PIK3CA during early stages of malignancy is unknown. Using a mouse model to activate the Pik3ca H1047R hotspot mutation in the heterozygous state from its endogenous locus, we here report that mutant Pik3ca induces centrosome amplification in cultured cells (through a pathway involving AKT, ROCK and CDK2/Cyclin E-nucleophosmin) and in mouse tissues, and increased in vitro cellular tolerance to spontaneous genome doubling. We also present evidence that the majority of PIK3CA H1047R mutations in the TCGA breast cancer cohort precede genome doubling. These previously unappreciated roles of PIK3CA mutation show that PI3K signalling can contribute to the generation of irreversible genomic changes in cancer. While this can limit the impact of PI3K-targeted therapies, these findings also open the opportunity for therapeutic approaches aimed at limiting tumour heterogeneity and evolution. Activated PI3K causes cancer, but the role of active PI3K mutations in early stages of malignancy are unclear. Here, the authors show in a mouse model that active PI3K induces centrosome amplification via AKT, ROCK, CDK2/Cyclin E and nucleophosmin, and increased tolerance of genome doubling.

Primary cilia are antenna-like organelles which sense extracellular cues and act as signalling hubs. Cilia dysfunction causes a heterogeneous group of disorders known as ciliopathy syndromes affecting most organs. Cilia disassembly, the process by which cells lose their cilium, is poorly understood but frequently observed in disease and upon cell transformation. Here, we uncover a role for the PI3Kα signalling enzyme in cilia disassembly. Genetic PI3Kα-hyperactivation, as observed in PIK3CA -related overgrowth spectrum (PROS) and cancer, induced a ciliopathy-like phenotype during mouse development. Mechanistically, PI3Kα and PI3Kβ produce the PIP 3 lipid at the cilia transition zone upon disassembly stimulation. PI3Kα activation initiates cilia disassembly through a kinase signalling axis via the PDK1/PKCι kinases, the CEP170 centrosomal protein and the KIF2A microtubule-depolymerising kinesin. Our data suggest diseases caused by PI3Kα-activation may be considered ‘Disorders with Ciliary Contributions’, a recently-defined subset of ciliopathies in which some, but not all, of the clinical manifestations result from cilia dysfunction. Primary cilia are cell organelles disrupted in developmental diseases and cancer. Here, the authors identify cilia regulators that generate a specific cilia membrane lipid, which may help to better understand diseases caused by mutations in PI3-kinase subunits.

Vps34 PI3K is thought to be the main producer of phosphatidylinositol-3-monophosphate, a lipid that controls intracellular vesicular trafficking. The organismal impact of systemic inhibition of Vps34 kinase activity is not completely understood. Here we show that heterozygous Vps34 kinase-dead mice are healthy and display a robustly enhanced insulin sensitivity and glucose tolerance, phenotypes mimicked by a selective Vps34 inhibitor in wild-type mice. The underlying mechanism of insulin sensitization is multifactorial and not through the canonical insulin/Akt pathway. Vps34 inhibition alters cellular energy metabolism, activating the AMPK pathway in liver and muscle. In liver, Vps34 inactivation mildly dampens autophagy, limiting substrate availability for mitochondrial respiration and reducing gluconeogenesis. In muscle, Vps34 inactivation triggers a metabolic switch from oxidative phosphorylation towards glycolysis and enhanced glucose uptake. Our study identifies Vps34 as a new drug target for insulin resistance in Type-2 diabetes, in which the unmet therapeutic need remains substantial. Vps34 is a lipid kinase conserved from yeast to humans and involved in in intracellular vesicular trafficking and autophagy. Here Bilanges et al. show that inhibition of this kinase in mice improves glucose tolerance and diet-induced steatosis by modulating mitochondrial respiration and metabolism.

ObjectivesTo determine if a digital communication app improves care timelines for patients with suspected acute stroke/ST-elevation myocardial infarction (STEMI).DesignReal-world feasibility study, quasi-experimental design.SettingPrehospital (25 Ambulance Victoria branches) and within-hospital (2 hospitals) in regional Victoria, Australia.ParticipantsParamedics or emergency department (ED) clinicians identified patients with suspected acute stroke (onset <4.5 hours; n=604) or STEMI (n=247).InterventionThe Pulsara communication app provides secure, two-way, real-time communication. Assessment and treatment times were recorded for 12 months (May 2017–April 2018), with timelines compared between ‘Pulsara initiated’ (Pulsara) and ‘not initiated’ (no Pulsara).Primary outcome measureDoor-to-treatment (needle for stroke, balloon for STEMI) Secondary outcome measures: ambulance and hospital processes.ResultsStroke (no Pulsara n=215, Pulsara n=389) and STEMI (no Pulsara n=76, Pulsara n=171) groups were of similar age and sex (stroke: 76 vs 75 years; both groups 50% male; STEMI: 66 vs 63 years; 68% and 72% male). When Pulsara was used, patients were off ambulance stretcher faster for stroke (11(7, 17) vs 19(11, 29); p=0.0001) and STEMI (14(7, 23) vs 19(10, 32); p=0.0014). ED door-to-first medical review was faster (6(2, 14) vs 23(8, 67); p=0.0001) for stroke but only by 1 min for STEMI (3 (0, 7) vs 4 (0, 14); p=0.25). Door-to-CT times were 44 min faster (27(18, 44) vs 71(43, 147); p=0.0001) for stroke, and percutaneous intervention door-to-balloon times improved by 17 min, but non-significant (56 (34, 88) vs 73 (49, 110); p=0.41) for STEMI. There were improvements in the proportions of patients treated within 60 min for stroke (12%–26%, p=0.15) and 90 min for STEMI (50%–78%, p=0.20).ConclusionsIn this Australian-first study, uptake of the digital communication app was strong, patient-centred care timelines improved, although door-to-treatment times remained similar.

PTEN hamartoma tumour syndrome (PHTS), a rare disease caused by germline heterozygous PTEN variants, is associated with multi-organ/tissue overgrowth, autism spectrum disorder and increased cancer risk. Phenotypic variability in PHTS is partly due to diverse PTEN variants and the protein's multifaceted functions. PTEN is primarily a phosphatidylinositol(3,4,5)trisphosphate (PIP3) phosphatase regulating PI3K/AKT signalling but also maintains chromosomal stability through nuclear functions such as double-stranded (ds)DNA damage repair. Here, we show that PTEN-R173C, a pathogenic variant frequently found in PHTS and somatic cancer, has elevated PIP3 phosphatase activity that effectively regulates canonical PI3K/AKT signalling. However, PTEN-R173C is unstable and excluded from the nucleus. We generated Pten+/R173C mice which developed few tumours during their lifetime, aligning with normal PI3K/AKT signalling. However, they exhibited lymphoid hyperplasia, macrocephaly and brain abnormalities, associated with impaired nuclear functions of PTEN-R173C, demonstrated by reduced dsDNA damage repair. We integrated PHTS patient data with our mouse model results, and propose that defective nuclear functions of PTEN variants can predict the onset of PHTS phenotypes and that late-onset cancer in these individuals may arise from secondary genetic alterations, facilitated by compromised dsDNA repair.

The insulin/insulin‐like growth factor‐1 signalling (IIS) pathway regulates cellular and organismal metabolism and controls the rate of aging. Gain‐of‐function mutations in p110α, the principal mammalian IIS‐responsive isoform of PI 3‐kinase (PI3K), promote cancer. In contrast, loss‐of‐function mutations in p110α impair insulin signalling and cause insulin resistance, inducing a pre‐diabetic state. It remains unknown if long‐term p110α inactivation induces further metabolic deterioration over time, leading to overt unsustainable pathology. Surprisingly, we find that chronic p110α partial inactivation in mice protects from age‐related reduction in insulin sensitivity, glucose tolerance and fat accumulation, and extends the lifespan of male mice. This beneficial effect of p110α inactivation derives in part from a suppressed down‐regulation of insulin receptor substrate (IRS) protein levels induced by age‐related hyperinsulinemia, and correlates with enhanced insulin‐induced Akt signalling in aged p110α‐deficient mice. This temporal metabolic plasticity upon p110α inactivation indicates that prolonged PI3K inhibition, as intended in human cancer treatment, might not negatively impact on organismal metabolism. Graphical Abstract Inactivation of the principal insulin‐responsive form of PI3K, p110alpha renders mice resistant to age‐related fat accumulation and improves glucose homeostasis at middle age.

The organismal roles of the ubiquitously expressed class I PI3K isoform p110β remain largely unknown. Using a new kinase-dead knockin mouse model that mimics constitutive pharmacological inactivation of p110β, we document that full inactivation of p110β leads to embryonic lethality in a substantial fraction of mice. Interestingly, the homozygous p110β kinase-dead mice that survive into adulthood (maximum ~26% on a mixed genetic background) have no apparent phenotypes, other than subfertility in females and complete infertility in males. Systemic inhibition of p110β results in a highly specific blockade in the maturation of spermatogonia to spermatocytes. p110β was previously suggested to signal downstream of the c-kit tyrosine kinase receptor in germ cells to regulate their proliferation and survival. We now report that p110β also plays a germ cell-extrinsic role in the Sertoli cells (SCs) that support the developing sperm, with p110β inactivation dampening expression of the SC-specific Androgen Receptor (AR) target gene Rhox5, a homeobox gene critical for spermatogenesis. All extragonadal androgen-dependent functions remain unaffected by global p110β inactivation. In line with a crucial role for p110β in SCs, selective inactivation of p110β in these cells results in male infertility. Our study is the first documentation of the involvement of a signalling enzyme, PI3K, in the regulation of AR activity during spermatogenesis. This developmental pathway may become active in prostate cancer where p110β and AR have previously been reported to functionally interact.