OTD/OTX2 functional equivalence depends on 5′ and 3′ UTR-mediated control ofOtx2mRNA for nucleo-cytoplasmic export and epiblast-restricted translation

Development ◽  
2001 ◽  
Vol 128 (23) ◽  
pp. 4801-4813 ◽  
Author(s):  
Dario Acampora ◽  
Pietro Pilo Boyl ◽  
Massimo Signore ◽  
Juan Pedro Martinez-Barbera ◽  
Cristina Ilengo ◽  
...  
Keyword(s):  
Mouse Model ◽  
Transcriptional Control ◽  
Mrna Translation ◽  
Regulatory Control ◽  
Functional Equivalence ◽  
Control Mechanisms ◽  
Phenotypic Analysis ◽  
A Cell ◽  
Anterior Patterning

How gene activity is translated into phenotype and how it can modify morphogenetic pathways is of central importance when studying the evolution of regulatory control mechanisms. Previous studies in mouse have suggested that, despite the homeodomain-restricted homology, Drosophila orthodenticle (otd) and murine Otx1 genes share functional equivalence and that translation of Otx2 mRNA in epiblast and neuroectoderm might require a cell type-specific post-transcriptional control depending on its 5′ and 3′ untranslated sequences (UTRs).In order to study whether OTD is functionally equivalent to OTX2 and whether synthesis of OTD in epiblast is molecularly dependent on the post-transcriptional control of Otx2 mRNA, we generated a first mouse model (otd2) in which an Otx2 region including 213 bp of the 5′ UTR, exons, introns and the 3′ UTR was replaced by an otd cDNA and a second mutant (otd2FL) replacing only exons and introns of Otx2 with the otd coding sequence fused to intact 5′ and 3′ UTRs of Otx2.otd2 and otd2FL mRNAs were properly transcribed under the Otx2 transcriptional control, but mRNA translation in epiblast and neuroectoderm occurred only in otd2FL mutants. Phenotypic analysis revealed that visceral endoderm (VE)-restricted translation of otd2 mRNA was sufficient to rescue Otx2 requirement for early anterior patterning and proper gastrulation but it failed to maintain forebrain and midbrain identity.Importantly, epiblast and neuroectoderm translation of otd2FL mRNA rescued maintenance of anterior patterning as it did in a third mouse model replacing, as in otd2FL, exons and introns of Otx2 with an Otx2 cDNA (Otx22c). The molecular analysis has revealed that Otx2 5′ and 3′ UTR sequences, deleted in the otd2 mRNA, are required for nucleo-cytoplasmic export and epiblast-restricted translation. Indeed, these molecular impairments were completely rescued in otd2FL and Otx22c mutants. These data provide novel in vivo evidence supporting the concept that during evolution pre-existing gene functions have been recruited into new developmental pathways by modifying their regulatory control.

scholarly journals Synergistic interactions between heterologous upstream activation elements and specific TATA sequences in a muscle-specific promoter.

1995 ◽  
Vol 15 (4) ◽  
pp. 1870-1878 ◽  
Author(s):  
J Grayson ◽  
R S Williams ◽  
Y T Yu ◽  
R Bassel-Duby
Keyword(s):  
Transcriptional Control ◽  
Muscle Development ◽  
Transcription Unit ◽  
Nuclear Factors ◽  
Binding Factor ◽  
A Cell ◽  
Cell Type Specific ◽  
Tata Sequence

Previous investigations have defined three upstream activation elements--CCAC, A/T, and TATA sequences--necessary for muscle-specific transcription of the myoglobin gene. In the present study, we demonstrate that these three sequences elements, prepared as synthetic oligonucleotide cassettes, function synergistically to constitute a cell-type-specific transcription unit. Previously, cognate binding factors that recognize the CCAC and TATA elements were identified. In this study we determine that the A/T element binds two nuclear factors, including myocyte enhancer factor-2 (MEF-2) and an apparently unknown factor we provisionally termed ATF35 (A/T-binding factor, 35 kDa). Mutations that alter in vitro binding of either MEF-2 or ATF35 to this site diminish promoter function in vivo. Functional synergism between factors binding the CCAC and A/T elements is sensitive to subtle mutations in the TATA sequence, recapitulating the unusual preference for specific TATA variants exhibited by the native myoglobin promoter. These results provide new insights into mechanisms that underlie the distinctive pattern of myoglobin gene regulation in mammalian muscle development and lay a foundation for further studies to elucidate general principles of transcriptional control of complex mammalian promoters through combinatorial actions of heterologous transcriptional factors.

Robust Factor IX Expression Following ZFN-Mediated Genome Editing in An Adult Mouse Model of Hemophilia B

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 668-668
Author(s):  
Xavier M Anguela ◽  
Rajiv Sharma ◽  
Hojun Li ◽  
Virginia Haurigot ◽  
Anand Bhagwat ◽  
...  
Keyword(s):  
Mouse Model ◽  
Genome Editing ◽  
Partial Hepatectomy ◽  
Transgene Expression ◽  
Target Site ◽  
Factor Ix ◽  
Regulatory Control ◽  
Neonatal Mice ◽  
Proliferation Of Hepatocytes

Abstract Abstract 668 As a therapeutic strategy, site-specific modification of the genome has the potential to avoid some of the disadvantages of traditional gene replacement approaches such as insertional mutagenesis and lack of endogenous regulatory control of expression. We have recently reported that zinc finger nuclease (ZFN) driven gene correction can be achieved in vivo in a neonatal mouse model of hemophilia by combining AAV-mediated delivery of both the ZFNs and a Factor IX donor template with homology to the targeted F.IX gene (Li et al., Nature, 2011). The mouse model carries a mutant human F.IX mini-gene (hF9mut) knocked into the ROSA26 locus and ZFN-mediated cleavage followed by donor-dependent repair results in restoration of functional F.IX expression. AAV-ZFN and AAV-Donor vectors were administered to neonatal mice, where the rapid proliferation of hepatocytes in the growing animal may promote genome editing through homology directed repair (HDR). Here we sought to investigate whether ZFN-mediated genome editing is feasible in adult animals with predominantly quiescent hepatocytes. Tail vein injection of the AAV-ZFN and AAV-Donor, containing a promoterless wild type factor IX insert flanked by arms of homology to the target site, into adult (8 week old) mice (n=17) resulted in stable (>10wk) circulating F.IX levels of 730–1900 ng/mL (15-38% of normal), whereas mice receiving ZFN alone (n=9) exhibited F.IX levels below detection (<15 ng/mL). Co-delivery of AAV-Mock (luciferase expressing) & AAV-Donor (n=9), yielded <65 ng/mL F.IX. Importantly, mice lacking the hF9mut gene averaged less than 100 ng/mL after receiving AAV-ZFN and AAV-Donor (n=8), suggesting that F.IX expression was derived from on-target genome editing. To eliminate the potential for hF.IX expression resulting from episomal (non-integrated) AAV genomes we performed a two-thirds partial hepatectomy two days after AAV administration. Liver regeneration following hepatectomy is known to substantially reduce expression from non-integrated AAV genomes yet no significant differences in transgene expression were observed compared to non-hepatectomized mice: circulating F.IX levels in the AAV-ZFN + AAV-Donor group (n=13) ranged between 678–1240 ng/mL, whereas mice receiving ZFN alone (n=8) or Mock + AAV-Donor (n=8) had no detectable F.IX expression, or <100 ng/mL F.IX, respectively. Taken together, these data suggest that the F.IX expression in ZFN + Donor treated mice was derived from stable correction of the genome at the intended target site. In summary, we have shown that synchronized cell proliferation of hepatocytes, either in neonatal mice or following partial hepatectomy, is not necessary to achieve highly efficient genome editing and resultant high levels of transgene expression in vivo. These findings substantially expand the potential of ZFN-mediated genome editing as a therapeutic modality. Disclosures: Doyon: Sangamo Biosciences: Employment. Gregory:Sangamo Biosciences: Employment. Holmes:Sangamo Biosciences: Employment.

scholarly journals An in vivo translation-reporter system for the study of protein synthesis in zebrafish embryos

2018 ◽  
Author(s):  
Inês Garcez Palha ◽  
Isabelle Anselme ◽  
Sylvie Schneider-Maunoury ◽  
François Giudicelli
Keyword(s):  
Protein Synthesis ◽  
Protease Inhibitor ◽  
Fluorescent Protein ◽  
Mrna Translation ◽  
Transgenic Zebrafish ◽  
Zebrafish Embryos ◽  
Reporter System ◽  
Control Of Gene Expression ◽  
A Cell

ABSTRACTControl of gene expression at the translation level is increasingly regarded as a key feature in many biological processes. Simple, inexpensive, and reliable procedures to visualise sites of protein production are required to allow observation of the spatiotemporal patterns of mRNA translation at subcellular resolution. We present a method, named SPoT (for Subcellular Patterns of Translation), developed upon the original TimeStamp technique (Lin et al., 2008), consisting in the expression of a fluorescent protein fused to a tagged, self-cleavable protease domain. Addition of a cell-permeable protease inhibitor instantly stabilizes newly produced, tagged protein allowing to distinguish recently synthesized protein from more ancient one. After a brief protease inhibitor treatment, the ratio of tagged vs non-tagged forms is highest at sites where proteins are the most recent, i.e. sites of synthesis. Therefore, by comparing tagged and non-tagged protein it is possible to spotlight sites of translation. By specifically expressing the SPoT cassette in neurons of transgenic zebrafish embryos, we reveal sites of neuronal protein synthesis in diverse cellular compartments during early development.

A Mouse Model of Hematopoietic Stem Cell Failure Associated with p53-Loss and Defective Fbw7-Dependent Cyclin E Regulation.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2297-2297
Author(s):  
Ka Tat Siu ◽  
Yanfei Xu ◽  
Mitra Bhattacharyya ◽  
Alexander C. Minella
Keyword(s):  
Cell Cycle ◽  
Mouse Model ◽  
Conflicts Of Interest ◽  
Cyclin E ◽  
Cell Cycle Control ◽  
Control Mechanisms ◽  
Wild Type ◽  
Self Renewal ◽  
Hematopoietic Stem

Abstract Abstract 2297 Recent findings have challenged the notion that increased proliferation of hematopoietic stem cells (HSCs) necessarily restricts their self-renewal capacity. We have studied the physiologic consequences to HSCs of ablating a key cell cycle regulatory mechanism, Fbw7-dependent cyclin E ubiquitination, using germline knock-in of a cyclin ET74A T393A allele. Fbw7 is a tumor suppressor that regulates the abundance of several oncoprotein substrates by ubiquitin-mediated proteolysis, including cyclin E, Notch, and c-Myc. Cyclin E overexpression in vivo is associated with increased proliferation in some cellular contexts as well as a variety of deleterious consequences, including genomic instability, senescence, or apoptosis. In HSCs, Fbw7-loss has been shown to induce self-renewal and multi-lineage reconstitution defects, and the effect of Fbw7-loss in HSCs has been ascribed to dysregulated Myc and Notch expression. Using the cyclin ET74A T393A mouse model, we tested the hypothesis that impaired Fbw7-mediated regulation of cyclin E, specifically, promotes HSC exhaustion due to loss of self-renewal capacity. We first examined bone marrow HSC counts and their cell cycle kinetics in cyclin E knock-in and wild-type control mice at steady state and following hematologic injury induced by 5-fluorouracil treatment. We found that cyclin E dysregulation reduces numbers of quiescent HSCs and increases cells in S/G2/M-phases, while decreasing total numbers of HSCs, phenotypes made more severe after recovery from hematologic stress. Using bromodeoxyuridine labeling studies, we found that excess cyclin E activity causes DNA hyper-replication in cyclin ET74A T393A HSCs in a cell autonomous manner. By enumerating multi-potent progenitors (MPPs), we ruled out increased rate of transit from HSC-to-MPP as a cause of the apparent exhaustion of cyclin E knock-in HSCs. Thus, dysregulated cyclin E in HSCs promotes both increased proliferation and depletion of the HSC pool. Serial transplantation further revealed peripheral blood reconstitution defects associated with cyclin ET74A T393A HSCs. Recently, we have found that p53 is activated by dysregulated cyclin E in hematopoietic cells in vivo, in association with phosphorylation of both p53 and Chk1 proteins, resembling a DNA damage-type response. Interestingly, p53-loss has been found to be associated with a gain of HSC self-renewal activity. We therefore hypothesized that p53-loss would rescue the self-renewal defect of cyclin E knock-in HSCs. Surprisingly, we discovered that cyclin ET74A T393A; p53-null HSCs showed evidence of significantly worse self-renewal and peripheral reconstitution, compared to p53-null HSCs, defects that are more severe than those associated with impaired Fbw7-mediated cyclin E control in the setting of wild-type p53 (Chi-squared test, p<0.0001). Thus, our data are consistent with the concept that intact p53 function, in the setting of oncogenic insult, can preserve partial HSC self-renewal capacity, and its loss in vivo is detrimental to HSC viability when accompanied by defects in cell cycle control mechanisms. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Inhibitor specificity of recombinant and endogenous caspase-9

2002 ◽  
Vol 366 (2) ◽  
pp. 595-601 ◽  
Author(s):  
Ciara A. RYAN ◽  
Henning R. STENNICKE ◽  
Victor E. NAVA ◽  
Jennifer B. BURCH ◽  
J. Marie HARDWICK ◽  
...  
Keyword(s):  
Survival Data ◽  
Sindbis Virus ◽  
Control Mechanisms ◽  
Caspase 9 ◽  
Natural Form ◽  
Free System ◽  
Apoptosis Protein ◽  
A Cell

Apoptosis triggered through the intrinsic pathway by radiation and anti-neoplastic drugs is initiated by the activation of caspase-9. To elucidate control mechanisms in this pathway we used a range of synthetic and natural reagents. The inhibitory potency of acetyl-Asp-Glu-Val-Asp-aldehyde ('Ac-DEVD-CHO'), benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone ('Z-VAD-FMK') and the endogenous caspase inhibitor X-chromosome-linked inhibitor of apoptosis protein ('XIAP') against recombinant caspase-9 were predictive of the efficacy of these compounds in a cell-free system. However, the viral proteins CrmA and p35, although potent inhibitors of recombinant caspase-9, had almost no ability to block caspase-9 in this system. These findings were also mirrored in cell expression studies. We hypothesize that the viral inhibitors CrmA and p35 are excluded from reacting productively with the natural form of active caspase-9 in vivo, making the potency of inhibitors highly context-dependent. This is supported by survival data from a mouse model of apoptosis driven by Sindbis virus expressing either p35 or a catalytic mutant of caspase-9. These results consolidate previous findings that CrmA is a potent inhibitor of caspase-9 in vitro, yet fails to block caspase-9-mediated cell death.

scholarly journals Systemic antisense therapeutics inhibiting DUX4 expression improves muscle function in an FSHD mouse model

2021 ◽  
Author(s):  
Ngoc Lu-Nguyen ◽  
Alberto Malerba ◽  
George Dickson ◽  
Linda Popplewell
Keyword(s):  
Mouse Model ◽  
Target Genes ◽  
Facioscapulohumeral Muscular Dystrophy ◽  
Aberrant Expression ◽  
Muscle Fibrosis ◽  
Double Transgenic Mouse ◽  
Antisense Approach ◽  
A Cell

AbstractAberrant expression of the double homeobox 4 (DUX4) gene in skeletal muscle causes muscle deterioration and weakness in Facioscapulohumeral Muscular Dystrophy (FSHD). Since the presence of a permissive pLAM1 polyadenylation signal is essential for stabilization of DUX4 mRNA and translation of DUX4 protein, disrupting the function of this structure can prevent expression of DUX4. We and others have shown promising results using antisense approaches to reduce DUX4 expression in vitro and in vivo following local intramuscular administration. Our group has developed further the antisense chemistries, and demonstrate here enhanced in vitro antisense efficacy. The optimal chemistry was conjugated to a cell-penetrating moiety, and for the first time in FSHD research has been systemically administered into a double-transgenic mouse model of FSHD. After four weekly treatments, mRNA quantities of DUX4 and target genes were reduced by 50% that led to a 5% increase in muscle mass, a 52% improvement in in situ muscle strength, and reduction of muscle fibrosis by 17%. Systemic DUX4 inhibition also improved the locomotor activity significantly and reduced the fatigue level by 22%. Our data overall demonstrate that the optimized antisense approach can contribute to future development of a therapeutic strategy for FSHD.

scholarly journals Reducing Aspergillus fumigatus Virulence through Targeted Dysregulation of the Conidiation Pathway

mBio ◽  
2020 ◽  
Vol 11 (1) ◽  
Author(s):  
James I. P. Stewart ◽  
Vinicius M. Fava ◽  
Joshua D. Kerkaert ◽  
Adithya S. Subramanian ◽  
Fabrice N. Gravelat ◽  
...  
Keyword(s):  
Mouse Model ◽  
Aspergillus Fumigatus ◽  
Vegetative Growth ◽  
Wall Structure ◽  
Invasive Infection ◽  
Phenotypic Analysis ◽  
Airborne Spores ◽  
Content Type

ABSTRACT Inhalation of conidia of the opportunistic mold Aspergillus fumigatus by immunocompromised hosts can lead to invasive pulmonary disease. Inhaled conidia that escape immune defenses germinate to form filamentous hyphae that invade lung tissues. Conidiation rarely occurs during invasive infection of the human host, allowing the bulk of fungal energy to be directed toward vegetative growth. We hypothesized that forced induction of conidiation during infection can suppress A. fumigatus vegetative growth, impairing the ability of this organism to cause disease. To study the effects of conidiation pathway dysregulation on A. fumigatus virulence, a key transcriptional regulator of conidiation (brlA) was expressed under the control of a doxycycline-inducible promoter. Time- and dose-dependent brlA overexpression was observed in response to doxycycline both in vitro and in vivo. Exposure of the inducible brlA overexpression strain to low doses of doxycycline under vegetative growth conditions in vitro induced conidiation, whereas high doses arrested growth. Overexpression of brlA attenuated A. fumigatus virulence in both an invertebrate and mouse model of invasive aspergillosis. RNA sequencing studies and phenotypic analysis revealed that brlA overexpression results in altered cell signaling, amino acid, and carbohydrate metabolism, including a marked upregulation of trehalose biosynthesis and a downregulation in the biosynthesis of the polysaccharide virulence factor galactosaminogalactan. This proof of concept study demonstrates that activation of the conidiation pathway in A. fumigatus can reduce virulence and suggests that brlA-inducing small molecules may hold promise as a new class of therapeutics for A. fumigatus infection. IMPORTANCE The mold Aspergillus fumigatus reproduces by the production of airborne spores (conidia), a process termed conidiation. In immunocompromised individuals, inhaled A. fumigatus conidia can germinate and form filaments that penetrate and damage lung tissues; however, conidiation does not occur during invasive infection. In this study, we demonstrate that forced activation of conidiation in filaments of A. fumigatus can arrest their growth and impair the ability of this fungus to cause disease in both an insect and a mouse model of invasive infection. Activation of conidiation was linked to profound changes in A. fumigatus metabolism, including a shift away from the synthesis of polysaccharides required for cell wall structure and virulence in favor of carbohydrates used for energy storage and stress resistance. Collectively, these findings suggest that activation of the conidiation pathway may be a promising approach for the development of new agents to prevent or treat A. fumigatus infection.

Ultrastructure of melanocyte-keratinocyte interactions and pigment transfer in vitro

1978 ◽  
Vol 36 (2) ◽  
pp. 650-651
Author(s):  
Raul I. Garcia ◽  
Evelyn A. Flynn ◽  
George Szabo
Keyword(s):  
Direct Injection ◽  
Skin Pigmentation ◽  
Freeze Fracture ◽  
Pigment Granule ◽  
Time Lapse ◽  
Ultrastructural Level ◽  
Lanthanum Tracer ◽  
A Cell

Skin pigmentation in mammals involves the interaction of epidermal melanocytes and keratinocytes in the structural and functional unit known as the Epidermal Melanin Unit. Melanocytes(M) synthesize melanin within specialized membrane-bound organelles, the melanosome or pigment granule. These are subsequently transferred by way of M dendrites to keratinocytes(K) by a mechanism still to be clearly defined. Three different, though not necessarily mutually exclusive, mechanisms of melanosome transfer have been proposed: cytophagocytosis by K of M dendrite tips containing melanosomes, direct injection of melanosomes into the K cytoplasm through a cell-to-cell pore or communicating channel formed by localized fusion of M and K cell membranes, release of melanosomes into the extracellular space(ECS) by exocytosis followed by K uptake using conventional phagocytosis. Variability in methods of transfer has been noted both in vivo and in vitro and there is evidence in support of each transfer mechanism. We Have previously studied M-K interactions in vitro using time-lapse cinemicrography and in vivo at the ultrastructural level using lanthanum tracer and freeze-fracture.

Nutrient-regulated gene expression in eukaryotes

2006 ◽  
Vol 73 ◽  
pp. 85-96 ◽  
Author(s):  
Richard J. Reece ◽  
Laila Beynon ◽  
Stacey Holden ◽  
Amanda D. Hughes ◽  
Karine Rébora ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Transcriptional Control ◽  
Direct Interaction ◽  
Signalling Pathways ◽  
A Cell ◽  
One Step ◽  
Higher Eukaryotes ◽  
Regulated Gene Expression

The recognition of changes in environmental conditions, and the ability to adapt to these changes, is essential for the viability of cells. There are numerous well characterized systems by which the presence or absence of an individual metabolite may be recognized by a cell. However, the recognition of a metabolite is just one step in a process that often results in changes in the expression of whole sets of genes required to respond to that metabolite. In higher eukaryotes, the signalling pathway between metabolite recognition and transcriptional control can be complex. Recent evidence from the relatively simple eukaryote yeast suggests that complex signalling pathways may be circumvented through the direct interaction between individual metabolites and regulators of RNA polymerase II-mediated transcription. Biochemical and structural analyses are beginning to unravel these elegant genetic control elements.

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