Coordination of cell proliferation and cell death is essential to attain proper organ size during development and for maintaining tissue homeostasis throughout postnatal life. In Drosophila, these two processes are orchestrated by the Hippo kinase cascade, a growth-suppressive pathway that ultimately antagonizes the transcriptional coactivator Yorkie (Yki). Here we demonstrate that a single phosphorylation site in Yki mediates the growth-suppressive output of the Hippo pathway. Hippo-mediated phosphorylation inactivates Yki by excluding it from the nucleus, whereas loss of Hippo signaling leads to nuclear accumulation and therefore increased Yki activity. We further delineate a mammalian Hippo signaling pathway that culminates in the phosphorylation of YAP, the mammalian homolog of Yki. Using a conditional YAP transgenic mouse model, we demonstrate that the mammalian Hippo pathway is a potent regulator of organ size, and that its dysregulation leads to tumorigenesis. These results uncover a universal size-control mechanism in metazoan.
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http://dx.doi.org/10.1016/j.cell.2007.07.019 | DOI Listing |
Genetics
October 2023
Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, CA 95064, USA.
Severe defects in cell size are a nearly universal feature of cancer cells. However, the underlying causes are unknown. A previous study suggested that a hyperactive mutant of yeast Ras (ras2G19V) that is analogous to the human Ras oncogene causes cell size defects, which could provide clues to how oncogenes influence cell size.
View Article and Find Full Text PDFPhys Rev Lett
January 2023
Department of Physics, Washington University in St. Louis, St. Louis, Missouri 63130, USA and Department of Cell Biology & Physiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
One of the grand challenges in cellular biophysics is understanding the precision with which cells assemble and maintain subcellular structures. Organelle sizes, for example, must be flexible enough to allow cells to grow or shrink them as environments demand yet be maintained within homeostatic limits. Despite identification of molecular factors that regulate organelle sizes we lack insight into the quantitative principles underlying organelle size control.
View Article and Find Full Text PDFFront Microbiol
November 2022
Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin, China.
Phytoplankton cell size is well known as an essential functional trait, but its control factors are still unclear. Considering light provides the necessary energy for phytoplankton survival, we hypothesized that photosynthetic light energy utilization could influence phytoplankton cell size control. Several scenarios were conducted to understand the relationship between / and cell size for phytoplankton interspecies, and metatranscriptome in the field and transcriptome in the laboratory were used to understand relevant molecular mechanisms.
View Article and Find Full Text PDFDev Biol
July 2022
Department of Physiology, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390-9040, USA. Electronic address:
The development of a functional organ requires not only patterning mechanisms that confer proper identities to individual cells, but also growth-regulatory mechanisms that specify the final size of the organ. At the turn of the 21st century, comprehensive genetic screens in model organisms had successfully uncovered the major signaling pathways that mediate pattern formation in metazoans. In contrast, signaling pathways dedicated to growth control were less explored.
View Article and Find Full Text PDFJ Math Biol
December 2021
Department of Mathematics, Brandeis University, Waltham, MA, 02453, USA.
Organelle size control is a fundamental question in biology that demonstrates the fascinating ability of cells to maintain homeostasis within their highly variable environments. Theoretical models describing cellular dynamics have the potential to help elucidate the principles underlying size control. Here, we perform a detailed study of the active disassembly model proposed in Fai et al.
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