Role of GAS2L3 in cardiomyocyte proliferation and cytokinesis in vitro and in vivo
Developmental Biology
Final Report Abstract
The failure to undergo cytokinesis appears to be one of the limiting steps that prevents heart regeneration after injury. A better understanding of the mechanisms that control cardiac cell cycle progression and cytokinesis is therefore necessary to develop new therapies for heart diseases. We have recently identified GAS2L3 as a novel protein involved in cytokinesis. GAS2L3 is a target gene of YAP, the coactivator of the Hippo signaling pathway and of the MMB multiprotein complex, a master regulator of genes with functions in mitosis and cytokinesis. We found that GAS2L3 acts as a mitotic cytolinker protein that can cross-link actin filaments with the microtubule network. To investigate the in vivo function of GAS2L3 we have created a knockout mouse model. Gas2l3 k.o. mice die postnatally from dilated cardiomyopathy. Using conditional and non-conditional Gas2l3 knockout mouse lines we identified a role for GAS2L3 in cardiomyocyte cytokinesis during the critical postnatal period when cardiomyocytes binucleate and exit from the cell cycle. Premature cardiomyocyte binucleation observed in Gas2l3 animals was associated with a strong reduction in cardiomyocyte cell number. Further experiments suggest a role for GAS2L3 in cytkinetic abscission, the last step of cell division, but not in the overall organization of the sarcomere structure of cardiac muscle cells. Thus, a major conclusion from our work is that premature cardiomyocyte binucleation during cardiac development due to defects in abscission impairs cardiomyocyte proliferation resulting in dilated cardiomyopathy. The mitosis-specific expression of Gas2l3 is driven by the MMB complex, a master regulator of genes with functions in mitosis and cytokinesis. We have recently observed that MMB cooperates with YAP, the downstream effector of the Hippo pathway, to co-regulate an overlapping set of late cell cycle genes. Because the Hippo pathway and its downstream effectors YAP and TAZ are involved in cardiac development and have been implicated in heart regeneration after tissue damage, we studied the crosstalk between YAP and MMB during heart development. Using genetic models in mice we demonstrate that increased proliferation of embryonal and postnatal cardiomyocytes due to loss of the Hippo-signaling component SAV1 depends on the MMB complex. Similarly, we show that proliferation of postnatal cardiomyocytes induced by constitutive active YAP requires MMB. Genome wide studies revealed that YAP and MMB regulate an overlapping set of cell cycle genes in cardiomyocytes. YAP does not localize to the promoters of cell cycle genes but instead binds to enhancers, consistent with recent data from human cancer cell lines where YAP also predominantly binds to distant sites. This suggests that YAP interacts with MMB-regulated promoters through chromatin looping, resulting in the activation of a subset of cell cycle genes. Overall, our studies provide new insights into the mechanisms of cell cycle gene regulation during cardiac development. We demonstrate that premature cardiomyocyte binucleation impairs cardiomyocyte proliferation resulting in dilated cardiomyopathy.
Publications
- Deletion of Gas2l3 in mice leads to specific defects in cardiomyocyte cytokinesis during development. Proc Natl Acad Sci USA 114, 8029–8034 (2017)
Stopp S, Gründl M, Fackler M, Malkmus M, Leone M, Naumann R, Frantz S, Wolf E, von Eyss B, Engel FB and Gaubatz S
(See online at https://doi.org/10.1073/pnas.1703406114) - GAS2L3: Coordinator of cardiomyocyte cytokinesis? Cell Cycle 16, 1853–1854 (2017)
Gründl M, Engel FB & Gaubatz S
(See online at https://doi.org/10.1080/15384101.2017.1372546) - Interaction of YAP with the Myb-MuvB (MMB) complex defines a transcriptional program to promote the proliferation of cardiomyocytes. Plos Genet 16, e1008818 (2020)
Gründl M, Walz S, HaufI L, Schwab M, Werner K, Spahr S, Schulte C, Maric HM, Ade CP and Gaubatz S
(See online at https://doi.org/10.1371/journal.pgen.1008818) - IQGAP3, a YAP target, is required for proper cell cycle progression and genome stability. Mol Cancer Res (2021)
Leone M, Cazorla-Vázquez S, Ferrazzi F, Wiederstein J, Gründl M, Weinstock G, Vergarajauregui S, Eckstein M, Krüger M, Gaubatz S and Engel F
(See online at https://doi.org/10.1158/1541-7786.mcr-20-0639)
