Development
Abstract
Congenital microcephaly (MCPH) is a neurodevelopmental disease associated to mutations in genes encoding proteins involved in centrosomal and chromosomal dynamics during mitosis. Detailed MCPH pathogenesis at the cellular level is still elusive given the diversity of MCPH genes and lack of comparative in vivo studies. By generating a series of CRISPR/Cas9-mediated genetic knockouts we report here that, whereas defects in spindle pole proteins (ASPM, MCPH5) result in mild microcephaly during development, lack of centrosome (CDK5RAP2, MCPH3) or centriole (CEP135, MCPH8) regulators induces delayed chromosome segregation and chromosomal instability in neural progenitors (NPs). Our novel mouse model of MCPH8 suggests that Cep135 deficiency results in centriole duplication, TP53 activation and cell death of NPs. Trp53 ablation in a Cep135-deficient background prevents cell death, but not microcephaly, and leads to subcortical heterotopias, a malformation seen in MCPH8 patients. These results suggest that microcephaly in some MCPH patients can arise from the lack of adaptation to centriole defects in NPs and may lead to architectural defects if chromosomally unstable cells are not eliminated during brain development.
Authors
José González-Martínez, Andrzej W. Cwetsch, Diego Martínez-Alonso, Luis R. López-Sainz, Jorge Almagro, Anna Melati, Jesús Gómez, Manuel Pérez-Martínez, Diego Megías, Jasminka Boskovic, Javier Gilabert-Juan, Osvaldo Graña Castro, Alessandra Pierani, Axel Behrens, Sagrario Ortega, Marcos Malumbres
Taspase1 orchestrates fetal liver hematopoietic stem cell and vertebrae fates through cleaving TFIIA
Abstract
Taspase1, a highly conserved threonine protease encoded by TASP1, cleaves nuclear histone modifying factors and basal transcription regulators to orchestrate diverse transcription programs. Hereditary loss-of-function mutation of TASP1 has recently been reported in human resulting in a novel anomaly complex syndrome manifested with hematological, facial, and skeletal abnormalities. Here, we demonstrate that Taspase1-mediated cleavage of TFIIAα-β, rather than of MLL1 or MLL2, in mouse embryos is required for proper fetal liver hematopoiesis and correct segmental identities of the axial skeleton. Homozygous genetic deletion of Taspase1 (Tasp1-/-) disrupted embryonic hematopoietic stem cell self-renewal and quiescence states, and axial skeleton fates. Strikingly, mice carrying knockin non-cleavable mutations of TFIIAα-β (Gtf2a1nc/nc), a well-characterized basal transcription factor, displayed more pronounced fetal liver and axial skeleton defects than those with non-cleavable MLL1 and MLL2 (Mll1nc/nc;2nc/nc), two trithorax group (Trx-G) histone H3 trimethyl transferases. Our study offers molecular insights concerning TASP1-loss human syndrome and discovers unexpected role of TFIIAα-β cleavage in embryonic cell fate decisions.
Authors
Hidetaka Niizuma, Adam C. Searleman, Shugaku Takeda, Scott A. Armstrong, Christopher Y. Park, Emily H. Cheng, James J. Hsieh
Abstract
White adipose tissue not only serves as a reservoir for energy storage but also secretes a variety of hormonal signals and modulates systemic metabolism. A substantial amount of adipose tissue develops in early postnatal life, providing exceptional access to the formation of this important tissue. Although a number of factors have been identified that can modulate the differentiation of progenitor cells into mature adipocytes in cell-autonomous assays, it remains unclear which are connected to physiological extracellular inputs and are most relevant to tissue formation in vivo. Here, we elucidate that mature adipocytes themselves signal to adipose depot–resident progenitor cells to direct depot formation in early postnatal life and gate adipogenesis when the tissue matures. Our studies revealed that as the adipose depot matures, a signal generated in mature adipocytes is produced, converges on progenitor cells to regulate the cytoskeletal protein MYH9, and attenuates the rate of adipogenesis in vivo.
Authors
Sin Ying Cheung, Mohd Sayeed, Krishnamurthy Nakuluri, Liang Li, Brian J. Feldman
Abstract
The recently proposed glymphatic pathway for solute transport and waste clearance from the brain has been the focus of intense debate. By exploiting an isotopically enriched MRI tracer, H217O, we directly imaged glymphatic water transport in the rat brain in vivo for the first time. Our results reveal glymphatic transport that is dramatically faster and more extensive than previously thought and unlikely to be explained by diffusion alone. Moreover, we confirm the critical role of aquaporin-4 channels in glymphatic transport.
Authors
Mohammed S. Alshuhri, Lindsay Gallagher, Lorraine M. Work, William M. Holmes
Abstract
EPAS1, encoding HIF-2α, mutations were previously identified in a syndrome of multiple paragangliomas, somatostatinoma, and polycythemia. HIF-2α, when dimerized with HIF-1β, acts as an angiogenic transcription factor. Patients referred to our institution for new, recurrent, and/or metastatic paraganglioma or pheochromocytoma were confirmed for EPAS1-gain-of-function mutation; imaging was evaluated for vascular malformations. We evaluated the Epas1A529V transgenic syndrome mouse model, corresponding to the mutation initially detected in the patients (EPAS1A530V), for vascular malformations via intravital two photon microscopy of meningeal vessels, terminal vascular perfusion with Microfil silicate polymer and subsequent intact ex vivo 14T MRI and Micro-CT, and histologic sectioning and staining of the brain and identified pathologies. Further, we evaluated retina from corresponding developmental timepoints (P7, P14, and P21) and the adult dura via immunofluorescent labeling of vessels and confocal imaging. We identified a spectrum of vascular malformations in all 9 syndromic patients and in all of our tested mutant mice. Patient vessels had higher variant allele frequency than adjacent normal tissue. Veins of the murine retina and intracranial dura failed to regress normally at the expected developmental timepoints. These findings add vascular malformation as a new clinical feature of EPAS1-gain-of-function syndrome.
Authors
Jared S. Rosenblum, Herui Wang, Pauline M. Dmitriev, Anthony J. Cappadona, Panagiotis Mastorakos, Chen Xu, Abhishek Jha, Nancy Edwards, Danielle R. Donahue, Jeeva Munasinghe, Matthew A. Nazari, Russell H. Knutsen, Bruce R. Rosenblum, James G. Smirniotopoulos, Alberto Pappo, Robert F. Spetzler, Alexander Vortmeyer, Mark R. Gilbert, Dorian B. McGavern, Emily Chew, Beth A. Kozel, John D. Heiss, Zhengping Zhuang, Karel Pacak
Abstract
Impairment of GABAergic system has been reported in epilepsy, autism, ADHD and schizophrenia. We recently demonstrated that Ataxia Telangiectasia Mutated (ATM) shapes directly the development of GABAergic system. Here, we show for the first time how the abnormal expression of ATM impacts the pathological condition of autism. We exploit two different animal models of autism, the Mecp2y/- mouse model of Rett syndrome, and mice prenatally exposed to valproic acid, and found increased ATM levels. Accordingly, the treatment with the specific ATM kinase inhibitor KU55933 (KU) normalises molecular, functional and behavioural defects in these mouse models such as the i) delayed GABAergic development, ii) hippocampal hyper-excitability, iii) low cognitive performances, iv) social impairments. Mechanistically, we demonstrate that KU administration to wild type hippocampal neurons leads to i) higher Egr4 activity on Kcc2b promoter, ii) increased expression of Mecp2, iii) potentiated GABA-transmission. These results provide evidences and molecular substrates for the pharmacological development of ATM inhibition in autism spectrum disorders.
Authors
Lara Pizzamiglio, Elisa Focchi, Clara Maria Cambria, Luisa Ponzoni, Silvia Ferrara, Francesco Bifari, Genni Desiato, Nicoletta Landsberger, Luca Murru, Maria Passafaro, Mariaelvina Sala, MIchela Matteoli, Elisabetta Menna, Flavia Antonucci
Abstract
Respiratory complicˆations are the major cause of morbidity and mortality among preterm infants, which is partially prevented by the administration of antenatal corticosteroids (ACS). Most very preterm infants are exposed to chorioamnionitis, but short- and long-term effects of ACS treatment in this setting are not well defined. In low-resource settings, ACS increased neonatal mortality by perhaps increasing infection. We report that treatment with low-dose ACS in the setting of inflammation induced by intraamniotic lipopolysaccharide (LPS) in rhesus macaques improves lung compliance and increases surfactant production relative to either exposure alone. RNA sequencing shows that these changes are mediated by suppression of proliferation and induction of mesenchymal cellular death via TP53. The combined exposure results in a mature-like transcriptomic profile with inhibition of extracellular matrix development by suppression of collagen genes COL1A1, COL1A2, and COL3A1 and regulators of lung development FGF9 and FGF10. ACS and inflammation also suppressed signature genes associated with proliferative mesenchymal progenitors similar to the term gestation lung. Treatment with ACS in the setting of inflammation may result in early respiratory advantage to preterm infants, but this advantage may come at a risk of abnormal extracellular matrix development, which may be associated with increased risk of chronic lung disease.
Authors
Augusto F. Schmidt, Paranthaman S. Kannan, James Bridges, Pietro Presicce, Courtney M. Jackson, Lisa A. Miller, Suhas G. Kallapur, Claire A. Chougnet, Alan H. Jobe
Abstract
Ongoing societal changes in views on medical and recreational roles of cannabis increased the use of concentrated plant extracts with a Δ9-tetrahydrocannabinol (THC) content of >90%. Even though prenatal THC exposure is widely considered adverse for neuronal development, equivalent experimental data for young age cohorts are largely lacking. Here, we administered plant-derived THC (1 or 5 mg/kg) to mice daily during postnatal days (P)5-16 and P5-35 and monitored its effects on hippocampal neuronal survival and specification by high resolution imaging and the hippocampal proteome by iTRAQ proteomics, respectively. We find that THC indiscriminately affects pyramidal cells and both cannabinoid receptor 1 (CB1R)+ and CB1R- interneurons by P16. THC particularly disrupted the expression of mitochondrial proteins (complexes I-IV), a change that had persisted even 4 months after the end of drug exposure. This was reflected by a THC-induced loss of membrane integrity occluding mitochondrial respiration and could be partially or completely rescued by pH stabilization, antioxidants, bypassed glycolysis, and targeting either mitochondrial soluble adenylyl cyclase or the mitochondrial voltage-dependent anion channel. Overall, THC exposure during infancy induces significant and long-lasting reorganization of neuronal circuits through mechanisms that, in a large part, render cellular bioenergetics insufficient to sustain key developmental processes in otherwise healthy neurons.
Authors
Johannes Beiersdorf, Zsofia Hevesi, Daniela Calvigioni, Jakob Pyszkowski, Roman A. Romanov, Edit Szodorai, Gert Lubec, Sally L. Shirran, Catherine H. Botting, Siegfried Kasper, Geoffrey W. Guy, Roy A. Gray, Vincenzo Di Marzo, Tibor Harkany, Erik Keimpema
Abstract
Pituitary developmental defects lead to partial or complete hormone deficiency and significant health problems. The majority of cases are sporadic and of unknown cause. We screened 28 patients with pituitary stalk interruption syndrome (PSIS) for mutations in the FAT/DCHS family of protocadherins that have high functional redundancy. We identified seven variants, four of which putatively damaging, in FAT2 and DCHS2 in six patients with pituitary developmental defects recruited through a cohort of patients with mostly ectopic posterior pituitary gland and/or pituitary stalk interruption. All patients had growth hormone deficiency and two presented with multiple hormone deficiencies and small glands. FAT2 and DCHS2 were strongly expressed in the mesenchyme surrounding the normal developing human pituitary. We analyzed Dchs2-/- mouse mutants and identified anterior pituitary hypoplasia and partially penetrant infundibular defects. Overlapping infundibular abnormalities and distinct anterior pituitary morphogenesis defects were observed in Fat4-/- and Dchs1-/- mouse mutants but all animal models displayed normal commitment to the anterior pituitary cell type. Together our data implicate FAT/DCHS protocadherins in normal hypothalamic-pituitary development and identify FAT2 and DCHS2 as candidates underlying pituitary gland developmental defects such as ectopic pituitary gland and/or pituitary stalk interruption.
Authors
Emily J. Lodge, Paraskevi Xekouki, Tatiane S. Silva, Cristiane Kochi, Carlos A. Longui, Fabio R. Faucz, Alice Santambrogio, James L. Mills, Nathan Pankratz, John Lane, Dominika Sosnowska, Tina Hodgson, Amanda L. Patist, Philippa Francis-West, Francoise Helmbacher, Constantine Stratakis, Cynthia L. Andoniadou
Abstract
Although congenital heart defects (CHDs) represent the most common birth defect, a comprehensive understanding of disease etiology remains unknown. This is further complicated since CHDs can occur in isolation or as a feature of another disorder. Analyzing disorders with associated CHDs provides a powerful platform to identify primary pathogenic mechanisms driving disease. Aberrant localization and expression of cathepsin proteases can perpetuate later-stage heart diseases, but their contribution toward CHDs is unclear. To investigate the contribution of cathepsins during cardiovascular development and congenital disease, we analyzed the pathogenesis of cardiac defects in zebrafish models of the lysosomal storage disorder mucolipidosis II (MLII). MLII is caused by mutations in the GlcNAc-1-phosphotransferase enzyme (Gnptab) that disrupt carbohydrate-dependent sorting of lysosomal enzymes. Without Gnptab, lysosomal hydrolases, including cathepsin proteases, are inappropriately secreted. Analyses of heart development in gnptab-deficient zebrafish show cathepsin K secretion increases its activity, disrupts TGF-β–related signaling, and alters myocardial and valvular formation. Importantly, cathepsin K inhibition restored normal heart and valve development in MLII embryos. Collectively, these data identify mislocalized cathepsin K as an initiator of cardiac disease in this lysosomal disorder and establish cathepsin inhibition as a viable therapeutic strategy.
Authors
Po-Nien Lu, Trevor Moreland, Courtney J. Christian, Troy C. Lund, Richard A. Steet, Heather Flanagan-Steet
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