Regulation of cellular proliferation by FSTL3

Supervisors: Dr Abir Mukherjee (amukherjee@rvc.ac.uk) Professor Tej Dhoot (TDhoot@RVC.AC.UK)

Exit from cell proliferation is necessary for cell fate specification, differentiation and maintenance of organ size. Misregulation of cell proliferation is at the core of numerous developmental, repair-related and age-onset disorders, including fibrosis and cancer. It is clear that TGFb ligands, including TGFb and activin, play key roles in the regulation of cell division (1), however, the precise mechanisms by which this signalling pathway affects cell division is unclear. Follistatin-like 3 (FSTL3) is a glycoprotein that is both secreted as well as nuclear and inhibits the action of activin and related TGFβ ligands (2). Evolutionarily it is conserved throughout the vertebrates. We have shown, in the FSTL3 deletion mouse (FSTL3 KO) that concomitant with increased activin signalling there is increased cell proliferation in tissues where FSTL3 is normally expressed. In the testis, increased cell proliferation was accompanied by loss of testicular size regulation (3). Furthermore, cultured FSTL3 KO mouse embryonic fibroblasts (MEF) proliferate faster than WT. FSTL3 might, therefore, play crucial roles in the control of cellular numbers and organ size.

Here we will test the hypotheses that FSTL3 regulates the cell cycle and plays key roles in limiting cell numbers. We will address the following aims:

1. Which cell cycle checkpoints are affected by FSTL3 deletion?

Cultured MEFs will be synchronised at different stages of the cell cycle and subsequent progression through the cycle assessed by flow cytometry and checkpoint associated markers assessed by immunofluorescence and western blotting.

2. Are cell-cell communications that help regulate cell numbers and organ size dysregulated in FSTL3 KO tissues and MEFs?

Cytoskeletal organisation in WT and KO proliferating primary cultures and in mouse tissues will be assessed by immunofluorescence. Effect of FSTL3 deletion on the Hippo signalling pathway and additional pathways crucially linked to organ size will be assessed by immunofluorescence and immunoblotting.  

References:

1. Roberts AB, Lamb LC, Newton DL, Sporn MB, De Larco JE, Todaro GJ. (1980) Transforming growth factors: isolation of polypeptides from virally and chemically transformed cells by acid/ethanol extraction. Proc Natl Acad Sci U S A. 77:3494-8.

2. Sidis Y, Mukherjee A, Keutmann H, Delbaere A, Sadatsuki M, Schneyer A. (2006) Biological activity of follistatin isoforms and follistatin-like-3 is dependent on differential cell surface binding and specificity for activin, myostatin, and bone morphogenetic proteins. Endocrinology. 147:3586-97.

3. Oldknow KJ, Seebacher J, Goswami T, Villen J, Pitsillides AA, O'Shaughnessy PJ, Gygi SP, Schneyer AL, Mukherjee A. (2013) Follistatin-like 3 (FSTL3) mediated silencing of transforming growth factor β (TGFβ) signaling is essential for testicular aging and regulating testis size. Endocrinology. 154:1310-20.  

If you would like to apply for this studentship please contact the supervisors in the first instance and then apply via UKPASS. See also the How to Apply box

The deadline for applications is 3rd April 2016