The mechanisms underlying the neurodevelopmental deficits associated with CHARGE syndrome, which include cerebellar hypoplasia, developmental delay, coordination problems, and autistic features, have not been identified. CHARGE syndrome has been associated with mutations in the gene encoding the ATP-dependent chromatin remodeler CHD7. CHD7 is expressed in neural stem and progenitor cells, but its role in neurogenesis during brain development remains unknown. Here we have shown that deletion of
Danielle E. Whittaker, Kimberley L.H. Riegman, Sahrunizam Kasah, Conor Mohan, Tian Yu, Blanca Pijuan Sala, Husam Hebaishi, Angela Caruso, Ana Claudia Marques, Caterina Michetti, María Eugenia Sanz Smachetti, Apar Shah, Mara Sabbioni, Omer Kulhanci, Wee-Wei Tee, Danny Reinberg, Maria Luisa Scattoni, Holger Volk, Imelda McGonnell, Fiona C. Wardle, Cathy Fernandes, M. Albert Basson
Failure of trabecular myocytes to undergo appropriate cell cycle withdrawal leads to ventricular noncompaction and heart failure. Signaling of growth factor receptor ERBB2 is critical for myocyte proliferation and trabeculation. However, the mechanisms underlying appropriate downregulation of trabecular ERBB2 signaling are little understood. Here, we have found that the endocytic adaptor proteins NUMB and NUMBL were required for downregulation of ERBB2 signaling in maturing trabeculae. Loss of NUMB and NUMBL resulted in a partial block of late endosome formation, resulting in sustained ERBB2 signaling and STAT5 activation. Unexpectedly, activated STAT5 overrode Hippo-mediated inhibition and drove YAP1 to the nucleus. Consequent aberrant cardiomyocyte proliferation resulted in ventricular noncompaction that was markedly rescued by heterozygous loss of function of either ERBB2 or YAP1. Further investigations revealed that NUMB and NUMBL interacted with small GTPase Rab7 to transition ERBB2 from early to late endosome for degradation. Our studies provide insight into mechanisms by which NUMB and NUMBL promote cardiomyocyte cell cycle withdrawal and highlight previously unsuspected connections between pathways that are important for cardiomyocyte cell cycle reentry, with relevance to ventricular noncompaction cardiomyopathy and regenerative medicine.
Maretoshi Hirai, Yoh Arita, C. Jane McGlade, Kuo-Fen Lee, Ju Chen, Sylvia M. Evans
Rapid impulse propagation in the heart is a defining property of pectinated atrial myocardium (PAM) and the ventricular conduction system (VCS) and is essential for maintaining normal cardiac rhythm and optimal cardiac output. Conduction defects in these tissues produce a disproportionate burden of arrhythmic disease and are major predictors of mortality in heart failure patients. Despite the clinical importance, little is known about the gene regulatory network that dictates the fast conduction phenotype. Here, we have used signal transduction and transcriptional profiling screens to identify a genetic pathway that converges on the NRG1-responsive transcription factor ETV1 as a critical regulator of fast conduction physiology for PAM and VCS cardiomyocytes.
Akshay Shekhar, Xianming Lin, Fang-Yu Liu, Jie Zhang, Huan Mo, Lisa Bastarache, Joshua C. Denny, Nancy J. Cox, Mario Delmar, Dan M. Roden, Glenn I. Fishman, David S. Park
Mutations in the T-box transcription factor TBX20 are associated with multiple forms of congenital heart defects, including cardiac septal abnormalities, but our understanding of the contributions of endocardial TBX20 to heart development remains incomplete. Here, we investigated how TBX20 interacts with endocardial gene networks to drive the mesenchymal and myocardial movements that are essential for outflow tract and atrioventricular septation. Selective ablation of
Cornelis J. Boogerd, Ivy Aneas, Noboru Sakabe, Ralph J. Dirschinger, Quen J. Cheng, Bin Zhou, Ju Chen, Marcelo A. Nobrega, Sylvia M. Evans
The molecular mechanisms that underlie spleen development and congenital asplenia, a condition linked to increased risk of overwhelming infections, remain largely unknown. The transcription factor TLX1 controls cell fate specification and organ expansion during spleen development, and
Elisa Lenti, Diego Farinello, Kazunari K. Yokoyama, Dmitry Penkov, Laura Castagnaro, Giovanni Lavorgna, Kenly Wuputra, Lisa L. Sandell, Naomi E. Butler Tjaden, Francesca Bernassola, Nicoletta Caridi, Anna De Antoni, Michael Wagner, Katja Kozinc, Karen Niederreither, Francesco Blasi, Diego Pasini, Gregor Majdic, Giovanni Tonon, Paul A. Trainor, Andrea Brendolan
Hemodynamic shear forces are intimately linked with cardiac development, during which trabeculae form a network of branching outgrowths from the myocardium. Mutations that alter Notch signaling also result in trabeculation defects. Here, we assessed whether shear stress modulates trabeculation to influence contractile function. Specifically, we acquired 4D (3D + time) images with light sheets by selective plane illumination microscopy (SPIM) for rapid scanning and deep axial penetration during zebrafish morphogenesis. Reduction of blood viscosity via
Juhyun Lee, Peng Fei, René R. Sevag Packard, Hanul Kang, Hao Xu, Kyung In Baek, Nelson Jen, Junjie Chen, Hilary Yen, C.-C. Jay Kuo, Neil C. Chi, Chih-Ming Ho, Rongsong Li, Tzung K. Hsiai
The sinoatrial node (SAN) maintains a rhythmic heartbeat; therefore, a better understanding of factors that drive SAN development and function is crucial to generation of potential therapies, such as biological pacemakers, for sinus arrhythmias. Here, we determined that the LIM homeodomain transcription factor ISL1 plays a key role in survival, proliferation, and function of pacemaker cells throughout development. Analysis of several
Xingqun Liang, Qingquan Zhang, Paola Cattaneo, Shaowei Zhuang, Xiaohui Gong, Nathanael J. Spann, Cizhong Jiang, Xinkai Cao, Xiaodong Zhao, Xiaoli Zhang, Lei Bu, Gang Wang, H.S. Vincent Chen, Tao Zhuang, Jie Yan, Peng Geng, Lina Luo, Indroneal Banerjee, Yihan Chen, Christopher K. Glass, Alexander C. Zambon, Ju Chen, Yunfu Sun, Sylvia M. Evans
Head morphogenesis requires complex signal relays to enable precisely coordinated proliferation, migration, and patterning. Here, we demonstrate that, during mouse head formation, taspase1-mediated (TASP1-mediated) cleavage of the general transcription factor TFIIA ensures proper coordination of rapid cell proliferation and morphogenesis by maintaining limited transcription of the negative cell cycle regulators
Shugaku Takeda, Satoru Sasagawa, Toshinao Oyama, Adam C. Searleman, Todd D. Westergard, Emily H. Cheng, James J. Hsieh
Appropriate development of stratified, squamous, keratinizing epithelia, such as the epidermis and oral epithelia, generates an outer protective permeability barrier that prevents water loss, entry of toxins, and microbial invasion. During embryogenesis, the immature ectoderm initially consists of a single layer of undifferentiated, cuboidal epithelial cells that stratifies to produce an outer layer of flattened periderm cells of unknown function. Here, we determined that periderm cells form in a distinct pattern early in embryogenesis, exhibit highly polarized expression of adhesion complexes, and are shed from the outer surface of the embryo late in development. Mice carrying loss-of-function mutations in the genes encoding IFN regulatory factor 6 (IRF6), IκB kinase-α (IKKα), and stratifin (SFN) exhibit abnormal epidermal development, and we determined that mutant animals exhibit dysfunctional periderm formation, resulting in abnormal intracellular adhesions. Furthermore, tissue from a fetus with cocoon syndrome, a lethal disorder that results from a nonsense mutation in
Rebecca J. Richardson, Nigel L. Hammond, Pierre A. Coulombe, Carola Saloranta, Heidi O. Nousiainen, Riitta Salonen, Andrew Berry, Neil Hanley, Denis Headon, Riitta Karikoski, Michael J. Dixon
Defective neurogenesis in the postnatal brain can lead to many neurological and psychiatric disorders, yet the mechanism behind postnatal neurogenesis remains to be investigated. Huntingtin-associated protein 1 (HAP1) participates in intracellular trafficking in neurons, and its absence leads to postnatal death in mice. Here, we used tamoxifen-induced (TM-induced) Cre recombination to deplete HAP1 in mice at different ages. We found that HAP1 reduction selectively affects survival and growth of postnatal mice, but not adults. Neurogenesis, but not gliogenesis, was affected in HAP1-null neurospheres and mouse brain. In the absence of HAP1, postnatal hypothalamic neurons exhibited reduced receptor tropomyosin-related kinase B (TRKB) levels and decreased survival. HAP1 stabilized the association of TRKB with the intracellular sorting protein sortilin, prevented TRKB degradation, and promoted its anterograde transport. Our findings indicate that intracellular sorting of neurotrophin receptors is critical for postnatal neurogenesis and could provide a therapeutic target for defective postnatal neurogenesis.
Jianxing Xiang, Hao Yang, Ting Zhao, Miao Sun, Xingshun Xu, Xin-Fu Zhou, Shi-Hua Li, Xiao-Jiang Li
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