Development
Abstract
The transcription factor ISL1 is expressed in pituitary gland stem cells and the thyrotrope and gonadotrope lineages. Pituitary-specific Isl1 deletion causes hypopituitarism with increased stem cell apoptosis, reduced differentiation of thyrotropes and gonadotropes, and reduced body size. Conditional Isl1 deletion causes development of multiple Rathke’s cleft-like cysts, with 100% penetrance. Foxa1 and Foxj1 are abnormally expressed in the pituitary gland and associated with a ciliogenic gene expression program in the cysts. We confirmed expression of FOXA1, FOXJ1 and stem cell markers in human Rathke's cleft cyst tissue, but not craniopharyngiomas, which suggests these transcription factors are useful, pathological markers for diagnosis of Rathke's cleft cysts. These studies support a model whereby expression of ISL1 in pituitary progenitors drives differentiation into thyrotropes and gonadotropes, and without it, activation of FOXA1 and FOXJ1 permits development of an oral epithelial cell fate with mucinous cysts. This pituitary specific Isl1 mouse knockout sheds light on the etiology of Rathke's cleft cysts and the role of ISL1 in normal pituitary development.
Authors
Michelle L. Brinkmeier, Hironori Bando, Adriana C. Camarano, Shingo Fujio, Koji Yoshimoto, Flávio S. J. de Souza, Sally A. Camper
Abstract
Esophageal atresia (EA/TEF) are common congenital abnormalities of the gastrointestinal tract. The etiology of EA/TEF is not well understood. We hypothesized that EA/TEF may be the direct consequence of abnormal expression of Noggin (NOG) signaling cascade. Here we showed that, in neonates with EA/TEF, NOG was missing from the atretic esophagus, resulting in immature esophagus that contains respiratory glands, and cilia. When using mouse esophageal organoid units (EOUs) or tracheal organoid units (TOU) as a model of foregut development in vitro, NOG determined the fate of foregut progenitors by allowing expression of esophageal epithelium proteins. When NOG was present in the culture of mTOU, it altered the cell morphology of the organoid unit epithelium, allowing expression of squamous cell proteins normally found in esophagus. On the other hand, when NOG was inhibited in mEOU, the organoid epithelium began to express respiratory markers mimicking the phenotype seen in pathology samples of human EA/TEF. Moreover, human EOU derived from EA/TEF patients were small, fibrotic and lack esophageal epithelium, but when NOG was added, the EOU grew larger, healthier and express esophageal proteins. These results indicate that Noggin is a critical regulator of cell fate decisions between esophageal and pulmonary morphogenesis.
Authors
Carolina Pinzon-Guzman, Sreedhara Sangadala, Katherine M. Riera, Evgenya Y. Popova, Elizabeth Manning, Won Jae Huh, Matthew S. Alexander, Julia S. Shelton, Scott D. Boden, James R. Goldenring
Abstract
Fowler syndrome is a rare autosomal recessive brain vascular disorder caused by mutation in FLVCR2 in humans. The disease occurs during a critical period of brain vascular development, is characterized by glomeruloid vasculopathy and hydrocephalus, and is almost invariably prenatally fatal. Here, we sought to gain insights into the process of brain vascularization and the pathogenesis of Fowler Syndrome by inactivating Flvcr2 in mice. We show that Flvcr2 is necessary for angiogenic sprouting in the brain, but surprisingly dispensable for maintaining the blood brain barrier. Endothelial cells lacking Flvcr2 have altered expression of angiogenic factors, fail to adopt tip-cell properties and display reduced sprouting leading to vascular malformations similar to those seen in humans with Fowler Syndrome. Brain hypo-vascularization is associated with hypoxia and tissue infarction, ultimately causing hydrocephalus and death of mutant animals. Strikingly, despite severe vascular anomalies and brain tissue infarction, the blood-brain barrier is maintained in Flvcr2 mutant mice. Our new Fowler syndrome models therefore define the pathobiology of this disease, and provide new insights into brain angiogenesis by showing uncoupling of vessel morphogenesis and blood-brain barrier formation.
Authors
Nicolas Santander, Carlos Omar Lizama, Eman Meky, Gabriel L. McKinsey, Bongnam Jung, Dean Sheppard, Christer Betsholtz, Thomas D. Arnold
Abstract
A majority (~95%) of the gas-exchange surface area is generated through septa formation during alveologenesis. Disruption of this process leads to alveolar simplification and bronchopulmonary dysplasia (BPD), a prevalent disorder in premature infants. Although several models have been proposed, the mechanism of septa formation remains under debate. Here we show that inactivation of myosin light chain kinase (MLCK), a key factor required for myofibroblast contraction, disrupted septa formation, supporting the myofibroblast contraction model of alveologenesis. The alveoli simplification phenotype was accompanied by decreased yes-associated protein (YAP), a key effector in the Hippo mechanotransduction pathway. Expression of activated YAP in Mlck-mutant lungs led to partial reversal of alveolar simplification. In the adult, although Mlck inactivation did not lead to simplification, it prevented reseptation during compensatory regrowth in the pneumonectomy model. These findings revealed that myofibroblast reactivation and contraction are requisite steps toward regenerating the gas-exchange surface in diseases such as BPD and chronic obstructive pulmonary disease (COPD).
Authors
Rongbo Li, Xiaoping Li, James Hagood, Min-Sheng Zhu, Xin Sun
Abstract
The prevalence of nonalcoholic fatty liver disease (NAFLD) is increasing worldwide. Although gene-environment interactions have been implicated in the etiology of several disorders, the impact of paternal and/or maternal metabolic syndrome on the clinical phenotypes of offspring and the underlying genetic and epigenetic contributors of NAFLD have not been fully explored. To this end, we used the liver-specific insulin receptor knockout (LIRKO) mouse, a unique nondietary model manifesting 3 hallmarks that confer high risk for the development of NAFLD: hyperglycemia, insulin resistance, and dyslipidemia. We report that parental metabolic syndrome epigenetically reprograms members of the TGF-β family, including neuronal regeneration–related protein (NREP) and growth differentiation factor 15 (GDF15). NREP and GDF15 modulate the expression of several genes involved in the regulation of hepatic lipid metabolism. In particular, NREP downregulation increases the protein abundance of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) and ATP-citrate lyase (ACLY) in a TGF-β receptor/PI3K/protein kinase B–dependent manner, to regulate hepatic acetyl-CoA and cholesterol synthesis. Reduced hepatic expression of NREP in patients with NAFLD and substantial correlations between low serum NREP levels and the presence of steatosis and nonalcoholic steatohepatitis highlight the clinical translational relevance of our findings in the context of recent preclinical trials implicating ACLY in NAFLD progression.
Authors
Dario F. De Jesus, Kazuki Orime, Dorota Kaminska, Tomohiko Kimura, Giorgio Basile, Chih-Hao Wang, Larissa Haertle, Renzo Riemens, Natalie K. Brown, Jiang Hu, Ville Männistö, Amélia M. Silva, Ercument Dirice, Yu-Hua Tseng, Thomas Haaf, Jussi Pihlajamäki, Rohit N. Kulkarni
Abstract
Prenatal alcohol exposure (PAE) affects at least 10% of newborns globally and leads to the development of fetal alcohol spectrum disorders (FASDs). Despite its high incidence, there is no consensus on the implications of PAE on metabolic disease risk in adults. Here, we describe a cohort of adults with FASDs that had an increased incidence of metabolic abnormalities, including type 2 diabetes, low HDL, high triglycerides, and female-specific overweight and obesity. Using a zebrafish model for PAE, we performed population studies to elucidate the metabolic disease seen in the clinical cohort. Embryonic alcohol exposure (EAE) in male zebrafish increased the propensity for diet-induced obesity and fasting hyperglycemia in adulthood. We identified several consequences of EAE that may contribute to these phenotypes, including a reduction in adult locomotor activity, alterations in visceral adipose tissue and hepatic development, and persistent diet-responsive transcriptional changes. Taken together, our findings define metabolic vulnerabilities due to EAE and provide evidence that behavioral changes and primary organ dysfunction contribute to resultant metabolic abnormalities.
Authors
Olivia Weeks, Gabriel D. Bossé, Isaac M. Oderberg, Sebastian Akle, Yariv Houvras, Paul J. Wrighton, Kyle LaBella, Isabelle Iversen, Sahar Tavakoli, Isaac Adatto, Arkadi Schwartz, Daan Kloosterman, Allison Tsomides, Michael E. Charness, Randall T. Peterson, Matthew L. Steinhauser, Pouneh K. Fazeli, Wolfram Goessling
Abstract
The atypical cadherin FAT4 has established roles in regulation of planar cell polarity and Hippo pathway signaling that are cell context dependent. The recent identification of FAT4 mutations in Hennekam syndrome, features of which include lymphedema, lymphangiectasia and mental retardation, uncovered an important role for FAT4 in the lymphatic vasculature. Hennekam syndrome is also caused by mutations in CCBE1 and ADAMTS3, encoding a matrix protein and protease, respectively, that regulate activity of the key pro-lymphangiogenic VEGF-C/VEGFR3 signaling axis by facilitating the proteolytic cleavage and activation of VEGF-C. The fact that FAT4, CCBE1 and ADAMTS3 mutations underlie Hennekam syndrome suggested that all three genes might function in a common pathway. We identified FAT4 as a target gene of GATA2, a key transcriptional regulator of lymphatic vascular development and in particular, lymphatic vessel valve development. Here, we demonstrate that FAT4 functions in a lymphatic endothelial cell autonomous manner to control cell polarity in response to flow and is required for lymphatic vessel morphogenesis throughout development. Our data reveal a crucial role for FAT4 in lymphangiogenesis and shed light on the mechanistic basis by which FAT4 mutations underlie a human lymphedema syndrome.
Authors
Kelly L. Betterman, Drew L. Sutton, Genevieve A. Secker, Jan Kazenwadel, Anna Oszmiana, Lillian Lim, Naoyuki Miura, Lydia Sorokin, Benjamin M. Hogan, Mark L. Kahn, Helen McNeill, Natasha L. Harvey
Abstract
Despite the effective clinical use of steroids for the treatment of Diamond Blackfan anemia (DBA), the mechanistic bases via which glucocorticoids regulate human erythropoiesis remain poorly understood. Here, we report that the sensitivity of erythroid differentiation to dexamethasone (Dex) is dependent on the developmental origin of human CD34+ progenitor cells, specifically increasing the expansion of CD34+ progenitors from peripheral blood (PB) but not cord blood (CB). Dexamethasone treatment of erythroid-differentiated PB, but not CB, CD34+ progenitors resulted in the expansion of a novel CD34+CD36+CD71hiCD105med immature colony-forming unit-erythroid (CFU-E) population. Furthermore, proteomics analyses revealed the induction of distinct proteins in dexamethasone-treated PB and CB erythroid progenitors. Dexamethasone treatment of PB progenitors resulted in the specific upregulation of p57Kip2, a Cip/Kip cyclin-dependent kinase inhibitor, and we identified this induction as critical; shRNA-mediated downregulation of p57Kip2, but not the related p27Kip1, significantly attenuated the impact of dexamethasone on erythroid differentiation and inhibited the expansion of the immature CFU-E subset. Notably, in the context of DBA, we found that steroid resistance was associated with a dysregulated p57Kip2 expression. Altogether, these data identify a novel glucocorticoid-responsive human erythroid progenitor and provide new insights into glucocorticoid-based therapeutic strategies for the treatment of patients with DBA.
Authors
Ryan J. Ashley, Hongxia Yan, Nan Wang, John Hale, Brian M Dulmovits, Julien Papoin, Meagan E. Olive, Namrata D Udeshi, Steven A. Carr, Adrianna Vlachos, Jeffrey M. Lipton, Lydie Da Costa, Christopher D. Hillyer, Sandrina Kinet, Naomi Taylor, Narla Mohandas, Anupama Narla, Lionel Blanc
Abstract
Multipass membrane proteins have a myriad of functions, including transduction of cell-cell signals, ion transport, and photoreception. Insertion of these proteins into the membrane depends on the endoplasmic reticulum (ER) membrane protein complex (EMC). Recently, birth defects have been observed in patients with variants in the gene encoding a member of this complex, EMC1. Patient phenotypes include congenital heart disease, craniofacial malformations, and neurodevelopmental disease. However, a molecular connection between EMC1 and these birth defects is lacking. Using Xenopus, we identified defects in neural crest cells (NCCs) upon emc1 depletion. We then used unbiased proteomics and discovered a critical role for emc1 in WNT signaling. Consistent with this, readouts of WNT signaling and Frizzled (Fzd) levels were reduced in emc1-depleted embryos, while NCC defects could be rescued with β-catenin. Interestingly, other transmembrane proteins were mislocalized upon emc1 depletion, providing insight into additional patient phenotypes. To translate our findings back to humans, we found that EMC1 was necessary for human NCC development in vitro. Finally, we tested patient variants in our Xenopus model and found the majority to be loss-of-function alleles. Our findings define molecular mechanisms whereby EMC1 dysfunction causes disease phenotypes through dysfunctional multipass membrane protein topogenesis.
Authors
Jonathan Marquez, June Criscione, Rebekah M. Charney, Maneeshi S. Prasad, Woong Y. Hwang, Emily K. Mis, Martín I. García-Castro, Mustafa K. Khokha
Abstract
Pituitary develops from oral ectoderm in contact with adjacent ventral hypothalamus. Impairment in this process results in congenital pituitary hypoplasia (CPH); however, there have been no human disease models for CPH thus far, prohibiting the elucidation of the underlying mechanisms. In this study, we established a disease model of CPH using patient-derived induced pluripotent stem cells (iPSCs) and 3D organoid technique, in which oral ectoderm and hypothalamus develop simultaneously. Interestingly, patient iPSCs with a heterozygous mutation in the orthodenticle homeobox 2 (OTX2) gene showed increased apoptosis in the pituitary progenitor cells, and the differentiation into pituitary hormone–producing cells was severely impaired. As an underlying mechanism, OTX2 in hypothalamus, not in oral ectoderm, was essential for progenitor cell maintenance by regulating LHX3 expression in oral ectoderm via FGF10 expression in the hypothalamus. Convincingly, the phenotype was reversed by the correction of the mutation, and the haploinsufficiency of OTX2 in control iPSCs revealed a similar phenotype, demonstrating that this mutation was responsible. Thus, we established an iPSC-based congenital pituitary disease model, which recapitulated interaction between hypothalamus and oral ectoderm and demonstrated the essential role of hypothalamic OTX2.
Authors
Ryusaku Matsumoto, Hidetaka Suga, Takashi Aoi, Hironori Bando, Hidenori Fukuoka, Genzo Iguchi, Satoshi Narumi, Tomonobu Hasegawa, Keiko Muguruma, Wataru Ogawa, Yutaka Takahashi
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Copyright © 2020 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)