ESR Project 11

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ESR Project 11: Seeking pathways affected in macrophages by Trib1 under- and overexpression

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Dominika Grzesik

 

Prostate cancer tumour microenvironment is affected by signals from adipose tissue that consists of both adipocytes and immune cells, including macrophages. Once those signals are dysregulated, this may alter the tumour environment, promote its growth and increase its aggressiveness.

Macrophages are important for remaining a proper body’s physiology. They take part in eradication of dead cells and other debris, maintaining homeostasis, but also in removing bacteria or other pathogens during inflammation as a part of an innate immune response (Ginhoux and Jung, 2014; Italiani and Boraschi, 2014).

They are developed during haematopoiesis, a process that gives rise to all blood elements. In adult tissues, macrophages derive from three sources: yolk sac, fetal liver and bone marrow, as primitive haematopoiesis in embryo first occurs in yolk sac, then moves to the liver and as the embryonic development continues, to finally reach the bone marrow (Italiani and Boraschi, 2014).

In quiescent conditions, macrophages take up to 10-15% of total cell number, with amount increasing during inflammation. They are virtually present in all tissues of the body and have different names according to their tissue localisation, for example those in the liver are called Kupffer cells and to those in skin we would refer to as Langerhaus cells (Epelman et al., 2014; Italiani and Boraschi, 2014).

Tribbles regulate the inflammatory state of AT depots, the microenvironments of tumour cells and signalling pathways that control tumour aggressiveness & metastatic spread in a cell- & isoform-specific manner.

It was previously shown that Trib1 plays an important role in regulation of macrophage behaviour both during inflammation and in the quiescent state as well (Liu et al., 2013; Satoh et al., 2013) and we also believe that it takes part in development and progression of prostate cancer.

Project aims:

  1. Defining the Visceral Adipose Tissue and Bone Marrow Derived Macrophage (BMDM) transcriptomes in:
    • myeloid specific Trib1 knockout ± high fat diets (HFD)
    • Trib1 overexpressing mice ± high fat diets (HFD)
  2. Investigating the pathways/networks affected by myeloid specific-Trib1 ablation/ overexpression.
  3. Defining factors regulating Trib1 levels in cell lines (e.g. oxidative stress).

In order to do that, I will use publicly available datasets and:

  • Mouse models
    • Trib1 wild type, myeloid specific knock out of Trib1 and myeloid specific Trib1 overexpressing model
  • Cell lines
    • Human THP-1
    • Murine RAW264.7

RNAseq will be performed on bone marrow derived macrophages from the mouse models both on normal chow and high fat diet or 16 weeks. This will reveal transcriptome changes between under- and overexpressors of Trib1 and may reveal pathways altered by Trib1 levels for further investigation. RNAseq and downstream analysis will be performed by Seqomics Biotechnology Ltd., where I will undertake my secondment.

References:

  1. Epelman S., Lavine K. J., Randolph G. J. (2014) Origin and Functions of Tissue Macrophages. Immunity 41(1):21-35.
  2. Ginhoux F. and Jung S. (2014) Monocytes and macrophages: developmental pathways and tissue homeostasis. Nature 14 392-404.
  3. Italiani P. and Boraschi D. (2014) From monocytes to M1/M2 macrophages: phenotypical vs. functional differentiation. Frontiers in Immunology 5:514.
  4. Liu Y., Tan K.A.L., Morisson I.W., Lamb J.R., Argyle D.J. (2013) Macrophage migration is controlled by Tribbles 1 through the interaction between C/EBPβ and TNF- α. Veterinary Immunology and Immunopathology 155:67– 75.
  5. Satoh T., Kidoya H., Naito H., Yamamoto M., Takemura N., Nakagawa K., Yoshioka Y., Morii E., Takakura N., Takeuchi O., Akira S. (2013) Critical role of Trib1 in differentiation of tissue-resident M2-like macrophages. Nature 495(7442):524-8.