Browsing by Subject "Embryonic development"

Now showing 1 - 7 of 7
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    Ciliary gene RPGRIP1L is required for hypothalamic arcuate neuron development
    (American Society for Clinical Investigation, 2019-02-07) Wang, Liheng; De Solis, Alain J.; Goffer, Yossef; Birkenbach, Kathryn E.; Engle, Staci E.; Tanis, Ross; Levenson, Jacob M.; Li, Xueting; Rausch, Richard; Purohit, Manika; Lee, Jen-Yi; Tan, Jerica; De Rosa, Maria Caterina; Doege, Claudia A.; Aaron, Holly L.; Martins, Gabriela J.; Brüning, Jens C.; Egli, Dieter; Costa, Rui; Berbari, Nicolas; Leibel, Rudolph L.; Stratigopoulos, George; Biology, School of Science
    Intronic polymorphisms in the α-ketoglutarate-dependent dioxygenase gene (FTO) that are highly associated with increased body weight have been implicated in the transcriptional control of a nearby ciliary gene, retinitis pigmentosa GTPase regulator-interacting protein-1 like (RPGRIP1L). Previous studies have shown that congenital Rpgrip1l hypomorphism in murine proopiomelanocortin (Pomc) neurons causes obesity by increasing food intake. Here, we show by congenital and adult-onset Rpgrip1l deletion in Pomc-expressing neurons that the hyperphagia and obesity are likely due to neurodevelopmental effects that are characterized by a reduction in the Pomc/Neuropeptide Y (Npy) neuronal number ratio and marked increases in arcuate hypothalamic-paraventricular hypothalamic (ARH-PVH) axonal projections. Biallelic RPGRIP1L mutations result in fewer cilia-positive human induced pluripotent stem cell-derived (iPSC-derived) neurons and blunted responses to Sonic Hedgehog (SHH). Isogenic human ARH-like embryonic stem cell-derived (ESc-derived) neurons homozygous for the obesity-risk alleles at rs8050136 or rs1421085 have decreased RPGRIP1L expression and have lower numbers of POMC neurons. RPGRIP1L overexpression increases POMC cell number. These findings suggest that apparently functional intronic polymorphisms affect hypothalamic RPGRIP1L expression and impact development of POMC neurons and their derivatives, leading to hyperphagia and increased adiposity.
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    Combined deficiency of Tet1 and Tet2 causes epigenetic abnormalities but is compatible with postnatal development
    (Elsevier, 2013) Dawlaty, Meelad M.; Breiling, Achim; Le, Thuc; Raddatz, Günter; Barrasa, M. Inmaculada; Cheng, Albert W.; Gao, Qing; Powell, Benjamin E.; Li, Zhe; Xu, Mingjiang; Faull, Kym F.; Lyko, Frank; Jaenisch, Rudolf; Pediatrics, School of Medicine
    Tet enzymes (Tet1/2/3) convert 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) in various embryonic and adult tissues. Mice mutant for either Tet1 or Tet2 are viable, raising the question of whether these enzymes have overlapping roles in development. Here we have generated Tet1 and Tet2 double-knockout (DKO) embryonic stem cells (ESCs) and mice. DKO ESCs remained pluripotent but were depleted of 5hmC and caused developmental defects in chimeric embryos. While a fraction of double-mutant embryos exhibited midgestation abnormalities with perinatal lethality, viable and overtly normal Tet1/Tet2-deficient mice were also obtained. DKO mice had reduced 5hmC and increased 5mC levels and abnormal methylation at various imprinted loci. Nevertheless, animals of both sexes were fertile, with females having smaller ovaries and reduced fertility. Our data show that loss of both enzymes is compatible with development but promotes hypermethylation and compromises imprinting. The data also suggest a significant contribution of Tet3 to hydroxylation of 5mC during development.
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    Down syndrome mouse models have an abnormal enteric nervous system
    (American Society for Clinical Investigation, 2019-04-18) Schill, Ellen M.; Wright, Christina M.; Jamil, Alisha; LaCombe, Jonathan M.; Roper, Randall J.; Heuckeroth, Robert O.; Biology, School of Science
    Children with trisomy 21 (Down syndrome [DS]) have a 130-fold increased incidence of Hirschsprung Disease (HSCR), a developmental defect where the enteric nervous system (ENS) is missing from distal bowel (i.e., distal bowel is aganglionic). Treatment for HSCR is surgical resection of aganglionic bowel, but many children have bowel problems after surgery. Post-surgical problems like enterocolitis and soiling are especially common in children with DS. To determine how trisomy 21 affects ENS development, we evaluated the ENS in two DS mouse models, Ts65Dn and Tc1. These mice are trisomic for many chromosome 21 homologous genes, including Dscam and Dyrk1a, which are hypothesized to contribute to HSCR risk. Ts65Dn and Tc1 mice have normal ENS precursor migration at E12.5 and almost normal myenteric plexus structure as adults. However, Ts65Dn and Tc1 mice have markedly reduced submucosal plexus neuron density throughout the bowel. Surprisingly, the submucosal neuron defect in Ts65Dn mice is not due to excess Dscam or Dyrk1a, since normalizing copy number for these genes does not rescue the defect. These findings suggest the possibility that the high frequency of bowel problems in children with DS and HSCR may occur because of additional unrecognized problems with ENS structure.
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    Glycogen Dynamics Drives Lipid Droplet Biogenesis during Brown Adipocyte Differentiation
    (Cell Press, 2019-11-05) Mayeuf-Louchart, Alicia; Lancel, Steve; Sebti, Yasmine; Pourcet, Benoit; Loyens, Anne; Delhaye, Stéphane; Duhem, Christian; Beauchamp, Justine; Ferri, Lise; Thorel, Quentin; Boulinguiez, Alexis; Zecchin, Mathilde; Dubois-Chevalier, Julie; Eeckhoute, Jérôme; Vaughn, Logan T.; Roach, Peter J.; Dani, Christian; Pederson, Bartholomew A.; Vincent, Stéphane D.; Staels, Bart; Duez, Hélène; Biochemistry and Molecular Biology, School of Medicine
    Browning induction or transplantation of brown adipose tissue (BAT) or brown/beige adipocytes derived from progenitor or induced pluripotent stem cells (iPSCs) can represent a powerful strategy to treat metabolic diseases. However, our poor understanding of the mechanisms that govern the differentiation and activation of brown adipocytes limits the development of such therapy. Various genetic factors controlling the differentiation of brown adipocytes have been identified, although most studies have been performed using in vitro cultured pre-adipocytes. We investigate here the differentiation of brown adipocytes from adipose progenitors in the mouse embryo. We demonstrate that the formation of multiple lipid droplets (LDs) is initiated within clusters of glycogen, which is degraded through glycophagy to provide the metabolic substrates essential for de novo lipogenesis and LD formation. Therefore, this study uncovers the role of glycogen in the generation of LDs.
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    Identification and characterization of Hand2 upstream genomic enhancers active in developing stomach and limbs
    (Wiley, 2024) Ferguson, Chloe A.; Firulli, Beth A.; Zoia, Matteo; Osterwalder, Marco; Firulli, Anthony B.; Pediatrics, School of Medicine
    Background: The bHLH transcription factor HAND2 plays important roles in the development of the embryonic heart, face, limbs, and sympathetic and enteric nervous systems. To define how and when HAND2 regulates these developmental systems, requires understanding the transcriptional regulation of Hand2. Results: Remarkably, Hand2 is flanked by an extensive upstream gene desert containing a potentially diverse enhancer landscape. Here, we screened the regulatory interval 200 kb proximal to Hand2 for putative enhancers using evolutionary conservation and histone marks in Hand2-expressing tissues. H3K27ac signatures across embryonic tissues pointed to only two putative enhancer regions showing deep sequence conservation. Assessment of the transcriptional enhancer potential of these elements using transgenic reporter lines uncovered distinct in vivo enhancer activities in embryonic stomach and limb mesenchyme, respectively. Activity of the identified stomach enhancer was restricted to the developing antrum and showed expression within the smooth muscle and enteric neurons. Surprisingly, the activity pattern of the limb enhancer did not overlap Hand2 mRNA but consistently yielded a defined subectodermal anterior expression pattern within multiple transgenic lines. Conclusions: Together, these results start to uncover the diverse regulatory potential inherent to the Hand2 upstream regulatory interval.
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    The roles of SMYD4 in epigenetic regulation of cardiac development in zebrafish
    (PLOS, 2018-08-15) Xiao, Deyong; Wang, Huijun; Hao, Lili; Guo, Xiao; Ma, Xiaojing; Qian, Yanyan; Chen, Hongbo; Ma, Jing; Zhang, Jin; Sheng, Wei; Shou, Weinian; Huang, Guoying; Ma, Duan; Pediatrics, School of Medicine
    SMYD4 belongs to a family of lysine methyltransferases. We analyzed the role of smyd4 in zebrafish development by generating a smyd4 mutant zebrafish line (smyd4L544Efs*1) using the CRISPR/Cas9 technology. The maternal and zygotic smyd4L544Efs*1 mutants demonstrated severe cardiac malformations, including defects in left-right patterning and looping and hypoplastic ventricles, suggesting that smyd4 was critical for heart development. Importantly, we identified two rare SMYD4 genetic variants in a 208-patient cohort with congenital heart defects. Both biochemical and functional analyses indicated that SMYD4(G345D) was pathogenic. Our data suggested that smyd4 functions as a histone methyltransferase and, by interacting with HDAC1, also serves as a potential modulator for histone acetylation. Transcriptome and bioinformatics analyses of smyd4L544Efs*1 and wild-type developing hearts suggested that smyd4 is a key epigenetic regulator involved in regulating endoplasmic reticulum-mediated protein processing and several important metabolic pathways in developing zebrafish hearts.
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    SMN deficiency negatively impacts red pulp macrophages and spleen development in mouse models of spinal muscular atrophy
    (Oxford University Press, 2017-03-01) Khairallah, Marie-Therese; Astroski, Jacob; Custer, Sarah K.; Androphy, Elliot J.; Franklin, Craig L.; Lorson, Christian L.; Dermatology, School of Medicine
    Spinal muscular atrophy (SMA) is a progressive neurodegenerative disease that is the leading genetic cause of infantile death. It is caused by a severe deficiency of the ubiquitously expressed Survival Motor Neuron (SMN) protein. SMA is characterized by α-lower motor neuron loss and muscle atrophy, however, there is a growing list of tissues impacted by a SMN deficiency beyond motor neurons. The non-neuronal defects are observed in the most severe Type I SMA patients and most of the widely used SMA mouse models, however, as effective therapeutics are developed, it is unclear whether additional symptoms will be uncovered in longer lived patients. Recently, the immune system and inflammation has been identified as a contributor to neurodegenerative diseases such as ALS. To determine whether the immune system is comprised in SMA, we analyzed the spleen and immunological components in SMA mice. In this report, we identify: a significant reduction in spleen size in multiple SMA mouse models and a pathological reduction in red pulp and extramedullary hematopoiesis. Additionally, red pulp macrophages, a discrete subset of yolk sac-derived macrophages, were found to be altered in SMA spleens even in pre-symptomatic post-natal day 2 animals. These cells, which are involved in iron metabolism and the phagocytosis of erythrocytes and blood-borne pathogens are significantly reduced prior to the development of the neurodegenerative hallmarks of SMA, implying a differential role of SMN in myeloid cell ontogeny. Collectively, these results demonstrate that SMN deficiency impacts spleen development and suggests a potential role for immunological development in SMA.