This review is divided into three parts. We first describe how YAP/TAZ actually underlies many basic characteristics of cancer cells; In the second part, we review a large amount of work on the specific roles of YAP/TAZ in various human tumors and the corresponding mouse models. In the third part, we will describe in detail the different YAP/TAZ regulatory mechanisms, including the Hippo and non-Hippo regulations. The reader should be aware of a potentially confusing semantic problem in this area: the term “hippo signaling pathway”, which originally referred to a specific set of kinases such as hippopotamus/STD or LATS that ultimately cause inhibitory phosphorylation YAP/TAZ, is in fact often used vaguely to indicate essentially all YAP/TAZ control modalities. and thus essentially as a substitute for the “YAP/TAZ activity” itself. In contrast, we stick to the biochemical definition and therefore our “hippopotamus signaling” invariably refers to the hippopotamus kinase module (Box 1). Finally, we conclude this article with some future prospects for YAP/TAZ in cancer biology. That being said, we took the reviewer`s comment seriously and used a model-independent method to estimate Ymax. In this case, Ymax is simply the number of nuclei/depressions at which population growth reaches a plateau (the rate of change is zero; Ymax`). We estimate the growth rate (k`) by fitting only the previous points in time for each data set to an exponential growth equation. Not surprisingly, this analysis gives qualitatively similar results, since k in the logistic function is by definition equal to the exponential growth rate at low density. Changes to the maximum number of cells (Ymax`) are also preserved.
As Ymax` and k` do not change the conclusions of the manuscript, we continue to use logistical adequacy in the main characters. Maisonpierre, P. C., Suri, C., Jones, P. F., Bartunkova, S., Wiegand, S. J., Radziejewski, C., et al. (1997). Angiopoietin-2, a natural Tie2 antagonist that interferes with angiogenesis in vivo. Science 277, 55-60. doi: 10.1126/science.277.5322.55 Hanahan, D. (1997).
Signaling of vascular morphogenesis and preservation. Science 277, 48-50. doi: 10.1126/science.277.5322.48 Florey Institute of Neuroscience and Medical Health, University of Melbourne, Melbourne, 3010, Victoria, Australia We thank Dr. Rachel Thomson for her technical assistance and Dr. Iska Carmichael, Monash Micro Imaging facility, AMREP campus, BakerIDI. This work was awarded through Project grants (1009995 to P.G. and K.F.H., 1008910 to B.J.T.) and is supported by Australia`s National Health and Medical Research Council (NHMRC). K.F.H. is a Senior Medical Research Fellow of Sylvia and Charles Viertel. P.G.
is supported by a Career Development Fellowship (NHMRC) (1046782) and was previously supported by a Senior Research Fellowship sponsored by Pfizer Australia. B.J.T. is supported by the Susie Harris Memorial Fund, MND Research Grant, MND Research Institute of Australia. The Baker IDI Heart and Diabetes Institute and the Florey Institute of Neuroscience and Medical Health are supported in part by the Victorian Government`s Operational Infrastructure Support Program. The cells were trypsinized into a single-celled suspension. 10^6 cells were counted per condition, thoroughly washed in PBS and fixed for 20 minutes in an ice solution of 4% PFA. The cells were then washed in PBS and permeabilized with 0.5% Triton-X for 10 minutes at room temperature. After repeated washing, the cells were held on ice with a 10 ug/ml Hoechst 3342 succinimidyl ester and/or 0.4 ug/ml of Alexa Fluor 647 (Invitrogen) for 45 min in a light-protected tube before being analyzed on an LSRII flow cytometer (BD Biosciences). Sign up for the Nature Briefing newsletter – what matters in science, every day for free in your inbox. PubMed Abstract | CrossRef full text | Google Scholar. Ebos, J.
M., Lee, C. R., & Kerbel, R. S. (2009). Tumor- and host-mediated resistance pathways and disease progression in response to antiangiogenic therapy. Blinking. Cancer Res. 15, 5020-5025.
doi: 10.1158/1078-0432.CCR-09-0095 We naturally agree with the reviewer that control over organ size (with potentially limitless limits to growth) and growth of a population on a shell can be determined by a variety of factors. We now clarify that this article is not concerned with organ size control and that the tissue culture system is not used to draw unambiguous parallels with the regulation of organ size in vivo. That is, the cells multiply and die, and the cells are of medium size. These can and will vary independently of each other physiologically and in case of disorders. We simply used the tissue culture system to learn more about the effect of YAP on (1) cell size, (2) cell division, and (3) mortality rates. Since the balance of the three parameters affects organ growth, the findings might be relevant to how YAP regulates organ size, but a specific conclusion about organ size goes beyond our experiments. Our interpretation of our results related to organ size is speculative at best, and it is up to future experiments to show how organs contribute to organ growth and size regulation. It is not clear to us whether the examiner thinks we are confused (we are not) or that we might confuse others. We clarified this in the discussion, in which we discuss in more detail the relevance that our tissue culture findings might have for controlling organ size in a hopefully non-dogmatic way. For the sake of clarity, we have also distinguished in the introduction between the in vivo context and the cultural context.
Poon, C. L., Lin, J. I., Zhang, X., and Harvey, K. F. (2011). Sterile kinase type 20 Tao-1 controls tissue growth by regulating the Salvadoran wart-hippopotamus pathway. Cell 21, 896-906. doi: 10.1016/j.devcel.2011.09.012. To confirm that changes in the nucleus surface reflect changes in biomass and not just changes in volume, we measured protein mass directly in individual cells using a lysine-specific covalent dye on the protein, which is an indicator of size changes (Kafri et al., 2013). We found that the mean protein content per cell in low-density populations expressing YAP5SA (Figure 1F, G) was ~30% higher than in nGFP controls.
We also observed that cells seeded to four times the density had ~25% less protein (Figure 1F, G). These protein mass measurements reinforced the two conclusions drawn from nuclear surface changes: (1) YAP5SA cells are larger than control cells in low-density cultures, and (2) cell size decreases with higher cell population density. We excluded that the changes were solely due to an increase in the cell fraction in S or G2/M by simultaneous measurement of DNA and proteins (Figure 1 – Figure Supplement 5B–C).