Isoforms of PI 3-kinase as novel regulators of dsRNA-sensing and inflammation

This proposal seeks to investigate the roles of important regulators of fundamental processes inside mammalian cells, called phosphoinositide 3-kinases (or PI3Ks in short).

One function of PI3Ks is to transmit signals from the outside to the inside of cells, and make the cells respond in appropriate ways. This process is called signal transduction. Another function is to remodel intracellular membranes to control a process called vesicular trafficking. Signal transduction and vesicular trafficking are interconnected, but much needs to be learned about how this works.

Mammalian cells have eight family members of PI3K, divided in three subgroups. An important scientific question is to clarify the functions of the different PI3K family members and find out how they work.

Thus far, scientists have mainly studied the group I PI3Ks and discovered specialised functions of the different family members, both in healthy tissue and in cancer, inflammation and diabetes. Drugs against group I PI3Ks are currently being tested in clinical trials in human cancer and allergy. The group III PI3K has been shown to be important for the distribution and processing of materials taken up by cells, as well as for a process called self-eating that helps to keep the cell clean and organized.

At the moment, very little is known about the group II PI3Ks, especially about the processes they control in cells and whether they could be useful drug targets. In this proposal, we plan to explore novel functions of the group II PI3Ks, and to find out how they carry out these roles at the cellular level. In exploratory studies, we have identified an important signal transduction process in which vesicular traffic and the group II PI3K appear to be involved. This is the detection of so-called pathogen-associated molecular patterns (PAMPs) by Toll-like receptors. These serve as detectors of foreign invaders exhibiting such PAMPs, such as viruses and bacteria, and are crucial for our body's immune response. These receptors have also been implicated in how vaccines work and more recently, in cancer. Some of these discoveries have been made by studying mice in which PI3Ks have been inactivated, in order to uncover what these PI3Ks do in the living organism, and how they work.

We believe that our proposed studies can clarify the mechanism by which group II PI3Ks control the interplay of endosomal traffic and the signalling by Toll-like receptors. This might, in future, provide the rationale to develop drugs that could interfere with these processes, to ultimately combat diseases where the immune system is deregulated, such as inflammatory conditions.

This is a fundamental science proposal that will enhance our knowledge about basic biological phenomena. In the longer term, it is possible that this research may lead to a better understanding of disease processes and to the development of new medicines.

Phosphoinositide 3-kinases (PI3Ks) are a conserved family of kinases that generate 3-phosphoinositide (3-PI) lipid second messengers inside cells to regulate cell growth, proliferation, survival, migration and intracellular vesicular transport.

Mammals have 8 isoforms, divided in 3 classes. The class I PI3Ks signal downstream of growth factor and G protein-coupled receptors and have been characterized in detail due to their implication in cancer, organismal metabolism and immunity/inflammation. The sole class III PI3K (vps34) has emerged as a key regulator of endosomal maturation and autophagy. The organismal and signalling roles of the kinase activity of the class II PI3Ks (C2a, C2b and C2g), however, remain poorly understood.

Class II PI3Ks generate phosphatidylinositol-3,4-bisphosphate (PI3,4P2) and PI3P, lipids that have been shown to regulate membrane traffic and to regulate select signalling events on endosomes. However, our understanding of how these lipid products regulate physiologically important processes remains very limited. Preliminary data from our laboratory have now implicated the class II PI3Ks in sensing of pathogen-associated molecular patterns by receptors of the innate immune system.

Using mouse models with kinase-inactivating mutations in the class II PI3Ks genes, we aim to:

(1) define the roles of the class II PI3Ks and their lipid product(s) in pattern-recognition receptor signalling, with an initial focus on PI3K-C2a. At a later stage, we will also explore the role of the vps34 class III PI3K, mainly using pharmacological inhibitors.
(2) delineate the consequences of these roles for innate immunity against pathogens as well as for the regulation of the inflammatory response.

This proposal has the potential to gain insight into processes of fundamental cell biological importance, and to decipher mechanisms of innate immunity and inflammation, with potential for therapeutic exploitation at a later stage.

We propose to investigate enzymes that play important roles in fundamental processes in cell biology and innate immunity, and are potential new drug targets in disease.

ACADEMIC BENEFICIARIES

Research outputs will be communicated through peer-reviewed publications and international scientific conferences.

Complementary training of the Named Postdoctoral Fellow (YP) - This grant will allow YP to harvest the results of his substantial investment in the studies that form the basis for this application. Moreover, the innate immunity and mouse biology aspects of the work will equip YP with expertise beyond his cell biological background, of interest to both academia and pharma. UCL's Professional Development Programme covers topics such as leadership, project management, grant writing and networking skills and annual UCL Staff Appraisals monitor and manage personal and professional development.

Academic drug development - The close involvement of the PI in academic drug development guarantees appropriate exploitation of the grants' output. UCL has recently set up a dedicated Drug Discovery Group which aims to build and exploit a UCL translational pipeline portfolio. This includes the 'Therapeutic Innovation Network' (TIN) cross-cutting theme, of which the small molecule TIN is chaired by the PI. We will therefore explore these options, also allowing us to partner with industry in the discovery of new drugs.

THE WIDER PUBLIC

A. Better molecular understanding of fundamental processes underlying disease - The proposed work may lead in the longer term to the development of new therapies to alleviate diseases, enhancing quality of life in the UK and worldwide:

1. Impaired signalling from viral sensors inducing type I interferons is increasingly being implicated in the control of intestinal inflammation. This proposal could contribute to improved patient stratification for interferon therapy of colitis.
2. Type I interferonopathies are inflammatory disorders that can be caused by activating mutations in Mda-5 and RIG-I. There is an unmet need for drug targets to specifically interfere with hyperactivation of these pathways.
3. Toll-like Receptors (TLRs) are drug targets in the context of vaccination, chronic inflammation and cancer. The identification of downstream kinases is of clear potential therapeutic importance as no endosomal TLR antagonist has yet made it to the clinic.

B. Public engagement - We will continue to actively engage in efforts to promote public understanding of the science underlying this proposal. Past outreach activities include National Science Week events for A-level students, presentations in schools, lab tours for charity donors and a Lab Open Day with hands-on lab tour.

C. Press & other public exposure - When new work is about to be published, we will draft news releases together with the UCL Communications Office to attract attention from national and international press, as with our previous work, in part selected by BBSRC for their Annual Reports.

COMMERCIAL SECTOR

The laboratory has ample experience in commercialising the output of research. Patents issued on p110delta PI3K were incorporated into the spin-out company PIramed, acquired by Roche in 2008 for USD 160 million. Patents issued on mass spectrometry technologies were incorporated in the spin-out company Activiomics, successfully taken over by hVIVO. We believe that our proposed research similarly has potential to enhance UK competitiveness and quality of life. Insight from this work will be used to demonstrate the therapeutic potential of class II PI3Ks to Pharma.

In addition, the project outputs will include research tools of potential use to industry including the PI3K mutant mice and immortalised cell lines derived thereof. We have experience in commercialising such research tools, for example our PI3K mutant mice have been licensed to Pharma for preclinical studies.