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Obesity-related metabolic diseases such as type 2 diabetes (T2D) and osteoporosis are major public health problems arising in part from dysregulation of mesenchymal stem cells (MSCs) which give rise to adipocytes and osteoblasts.

Obesity-related metabolic diseases such as type 2 diabetes (T2D) and osteoporosis are major public health problems arising in part from dysregulation of mesenchymal stem cells (MSCs) which give rise to adipocytes and osteoblasts. 

WNTs are a family of secreted glycoproteins which activate downstream signalling by binding to LRP5 receptors. WNT signalling plays a key role in MSC biology, adipogenesis and osteo-blastogenesis. Loss-of-function LRP5 variants lead to osteoporosis, increased prevalence of T2D, and upper-body obesity. Reciprocally, we have shown that subjects with high bone mass-associated LRP5 mutations exhibit both enhanced lower-body fat accumulation and insulin sensitivity. Mechanistically, LRP5 promotes healthy (i.e. lower body) obesity by promoting MSC proliferation and differentiation in a fat depot-specific manner via dose-dependent effects on WNT signalling. 

The aim of the project is to examine the role of LRP5-interacting proteins in the regulation of bone mass, fat distribution and metabolic health; as a means of defining the LRP5 signalling hub regulating MSC biology. Targets have been selected based on extensive proprietary and public (e.g. biochemical, genetic, gene expression) datasets. The successful student will use a combination of human physiological and in vitro functional studies. Human studies will examine the effects of common and/or low-frequency gene variants on bone density, regional adiposity and metabolic profile. These will benefit from access to the Oxford Biobank; comprising DNA, clinical, biochemical, dual-energy X-ray absorptiometry (DXA), and exome array genotype data from >8500 volunteers who can be recalled for clinical studies.

Experiments will include assessment of adipocyte number and size (histology) and determination of bone mass and fat distribution (DXA), and insulin sensitivity (clamp studies). In vitro functional studies will determine the role of LRP5-interacting proteins in human MSC biology. We will utilise established lentiviral vector systems to inducibly over-express and knock-down specific target genes in immortalised abdominal/gluteal and abdominal/visceral fat MSC pairs uniquely available in our group. These studies will be complemented by genomic editing experiments using CRISPR Cas9. The effects of these genetic manipulations on proliferation, differentiation (osteoblast/adipocyte), apoptosis, and WNT signalling will then be assessed. Where appropriate, studies will be complemented with reporter assays and chromatin conformation capture analyses (3C).

Training Opportunities

• Human physiology • Human MSC culture and differentiation • Adipose tissue histology • Lentiviral mediated gene knock-down, over-expression • Genome editing • Luciferase reporter assays.

The DPhil would be based at the Oxford Centre for Diabetes Endocrinology and Metabolism (OCDEDM). As well as the specific training detailed above, students will have access to a wide-range of seminars and training opportunities through the many research institutes and centres based in Oxford. Students are also able to attend the Methods and Techniques course run by the MRC Weatherall Institute of Molecular Medicine. This course runs through the year, ensuring that students have the opportunity to build a broad-based understanding of differing research techniques.

Generic skills training is offered through the Medical Sciences Division's Skills Training Programme. This programme offers a comprehensive range of courses covering many important areas of researcher development: knowledge and intellectual abilities, personal effectiveness, research governance and organisation, and engagement, influence and impact. Students are actively encouraged to take advantage of the training opportunities available to them.

The Department has a successful mentoring scheme, open to graduate students, which provides an additional possible channel for personal and professional development outside the regular supervisory framework. We hold an Athena SWAN Silver Award in recognition of our efforts to support the careers of female students and staff.

Publications

1 Christodoulides C, Lagathu C, Sethi JK, Vidal-Puig A.  Adipogenesis and WNT signalling.  Trends Endocrinol Metab.2009;20:16-24. 
2 Lagathu C, Christodoulides C, et al.  Dact1, a nutritionally regulated preadipocyte gene, controls adipogenesis by coordinating the Wnt/beta-catenin signaling network.  Diabetes.2009;58:609-19. 
3  Loh NY, Neville MJ, Marinou K, Hardcastle SA, Fielding BA, Duncan EL, McCarthy MI, Tobias JH, Gregson CL, KarpeF, and Christodoulides C. LRP5 regulates human body fat distribution by modulating adipose progenitor biology in a dose- and depot-specific fashion. Cell Metab. Feb. 2015;21:262-72.  
4 Lagathu C, Christodoulides C, et al. Secreted frizzled-related protein 1 regulates adipose tissue expansion and is dysregulatedin severe obesity.  Int J Obes (Lond). 2010;34:1695-705.  
5 Todorčević M, Hilton C, McNeil C, Christodoulides C, Hodson L, Karpe F, Pinnick KE. A cellular model for the investigation of depot specific human adipocyte biology  Adipocyte. 2017; 6:40-55.

Research Themes, Tools and Technologies

Supervisors

Key Dates for October 2018 Entry

Application deadline:  12 noon GMT on Monday 8 January 2018

Interviews for shortlisted candidates: Week commencing Monday 22 January 

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How to apply

To apply for a place on the DPhil in Medical Sciences you will need to submit an application using the online application form.

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