scholarly journals Spatial specification of mammalian eye territories by reciprocal transcriptional repression of Pax2 and Pax6

Development ◽  
2000 ◽  
Vol 127 (20) ◽  
pp. 4325-4334 ◽  
Author(s):  
M. Schwarz ◽  
F. Cecconi ◽  
G. Bernier ◽  
N. Andrejewski ◽  
B. Kammandel ◽  
...  
Keyword(s):  
Visual System ◽  
Transcriptional Repression ◽  
Ectopic Expression ◽  
Pax6 Gene ◽  
Loss Of Function ◽  
Pax6 Expression ◽  
Expression Domain ◽  
Enhancer Activity ◽  
Optic Stalk ◽  
Optic Cup

We have studied the molecular basis of the Pax2 and Pax6 function in the establishment of visual system territories. Loss-of-function mutants have revealed crucial roles for Pax2 in the generation of the optic stalk and for Pax6 in the development of the optic cup. Ectopic expression of Pax6 in the optic stalk under control of Pax2 promoter elements resulted in a shift of the optic cup/optic stalk boundary indicated by the presence of retinal pigmented cells on the optic stalk. By studying mouse embryos at early developmental stages we detected an expansion of Pax2 expression domain in the Pax6(−/−) mutant and of Pax6 expression domain in the Pax2(−/−) embryo. These results suggest that the position of the optic cup/optic stalk boundary depends on Pax2 and Pax6 expression, hinting at a possible molecular interaction. Using gel shift experiments, we confirmed the presence of Pax2- and Pax6-binding sites on the retina enhancer of the Pax6 gene and on the Pax2 upstream control region, respectively. Co-transfection experiments revealed a reciprocal inhibition of Pax2 promoter/enhancer activity by Pax6 protein and vice versa. Based on our findings, we propose a model for Pax gene regulation that establishes the proper spatial regionalization of the mammalian visual system.

The role of bone morphogenetic proteins in the differentiation of the ventral optic cup

Development ◽  
2002 ◽  
Vol 129 (13) ◽  
pp. 3161-3171 ◽  
Author(s):  
Ruben Adler ◽  
Teri L. Belecky-Adams
Keyword(s):  
Bone Morphogenetic Proteins ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Ectopic Expression ◽  
Neural Retina ◽  
Optic Disk ◽  
Loss Of Function ◽  
In Ovo ◽  
Optic Stalk ◽  
Optic Cup

The ventral region of the chick embryo optic cup undergoes a complex process of differentiation leading to the formation of four different structures: the neural retina, the retinal pigment epithelium (RPE), the optic disk/optic stalk, and the pecten oculi. Signaling molecules such as retinoic acid and sonic hedgehog have been implicated in the regulation of these phenomena. We have now investigated whether the bone morphogenetic proteins (BMPs) also regulate ventral optic cup development. Loss-of-function experiments were carried out in chick embryos in ovo, by intraocular overexpression of noggin, a protein that binds several BMPs and prevents their interactions with their cognate cell surface receptors. At optic vesicle stages of development, this treatment resulted in microphthalmia with concomitant disruption of the developing neural retina, RPE and lens. At optic cup stages, however, noggin overexpression caused colobomas, pecten agenesis, replacement of the ventral RPE by neuroepithelium-like tissue, and ectopic expression of optic stalk markers in the region of the ventral retina and RPE. This was frequently accompanied by abnormal growth of ganglion cell axons, which failed to enter the optic nerve. The data suggest that endogenous BMPs have significant effects on the development of ventral optic cup structures.

scholarly journals Crosstalk of CREB and Fos/Jun on a single cis-element: transcriptional repression of the steroidogenic acute regulatory protein gene

2007 ◽  
Vol 39 (4) ◽  
pp. 261-277 ◽  
Author(s):  
Pulak R Manna ◽  
Douglas M Stocco
Keyword(s):  
Transcriptional Repression ◽  
Protein Gene ◽  
Binding Protein ◽  
Regulatory Protein ◽  
Ectopic Expression ◽  
Fine Tuning ◽  
Creb Binding Protein ◽  
Loss Of Function ◽  
Cis Element ◽  
Steroidogenic Acute Regulatory

AbstractTranscriptional regulation of the steroidogenic acute regulatory (StAR) protein gene by cAMP-dependent mechanisms occurs in the absence of a consensus cAMP-response element (CRE; TGACGTCA) and is mediated by several sequence-specific transcription factors. We previously identified three CRE-like sites (within the −151/−1 bp cAMP-responsive region of the mouse StAR gene), of which the CRE2 site overlaps with an activator protein-1 (AP-1) motif (TGACTGA, designated as CRE2/AP-1) that can bind both CRE and AP-1 DNA-binding proteins. The present studies were aimed at exploring the functional crosstalk between CREB (CRE-binding protein) and cFos/cJun (AP-1 family members) on the CRE2/AP-1 element and its role in regulating transcription of the StAR gene. Using MA-10 mouse Leydig tumor cells, we demonstrate that the CRE and AP-1 families of proteins interact with the CRE2/AP-1 sequence. CREB, cFos, and cJun proteins were found to bind to the CRE2/AP-1 motif but not the CRE1 and CRE3 sites. Treatment with the cAMP analog (Bu)2cAMP augmented phosphorylation of CREB (Ser133), cFos (Thr325), and cJun (ser73). Chromatin immunoprecipitation studies revealed that the induction of CREB, cFos, and cJun by (Bu)2cAMP was correlated with protein–DNA interactions and recruitment of the coactivator CREB-binding protein (CBP) to the StAR promoter. EMSA studies employing CREB and cFos/cJun proteins demonstrated competition between these factors for binding to the CRE2/AP-1 motif. Transfection of cells containing the −151/−1 StAR reporter with CREB and cFos/cJun resulted in trans-repression of the StAR gene, an event tightly associated with CBP, demonstrating that both CREB and Fos/Jun compete with each other for binding with limited amounts of intracellular CBP. Overexpression of adenovirus E1A, which binds and inactivates CBP, markedly suppressed StAR gene expression. Ectopic expression of CBP eliminated the repression of the StAR gene by E1A and potentiated the activity of CREB and cFos/cJun on StAR promoter responsiveness. These findings identify molecular events involved in crosstalk between CREB and cFos/cJun, which confer both gain and loss of function on a single cis-element in fine-tuning of the regulatory events involved in transcription of the StAR gene.

scholarly journals Hedgehog-dependent E3-ligase Midline1 regulates ubiquitin-mediated proteasomal degradation of Pax6 during visual system development

2016 ◽  
Vol 113 (36) ◽  
pp. 10103-10108 ◽  
Author(s):  
Thorsten Pfirrmann ◽  
Enrico Jandt ◽  
Swantje Ranft ◽  
Ashwin Lokapally ◽  
Herbert Neuhaus ◽  
...  
Keyword(s):  
Visual System ◽  
Sonic Hedgehog ◽  
Transcriptional Repression ◽  
System Development ◽  
E3 Ligase ◽  
Proteasomal Degradation ◽  
Pax6 Expression ◽  
Pax6 Protein ◽  
Visual System Development ◽  
Major Domain

Pax6 is a key transcription factor involved in eye, brain, and pancreas development. Although pax6 is expressed in the whole prospective retinal field, subsequently its expression becomes restricted to the optic cup by reciprocal transcriptional repression of pax6 and pax2. However, it remains unclear how Pax6 protein is removed from the eyestalk territory on time. Here, we report that Mid1, a member of the RBCC/TRIM E3 ligase family, which was first identified in patients with the X-chromosome–linked Opitz BBB/G (OS) syndrome, interacts with Pax6. We found that the forming eyestalk is a major domain of mid1 expression, controlled by the morphogen Sonic hedgehog (Shh). Here, Mid1 regulates the ubiquitination and proteasomal degradation of Pax6 protein. Accordantly, when Mid1 levels are knocked down, Pax6 expression is expanded and eyes are enlarged. Our findings indicate that remaining or misaddressed Pax6 protein is cleared from the eyestalk region to properly set the border between the eyestalk territory and the retina via Mid1. Thus, we identified a posttranslational mechanism, regulated by Sonic hedgehog, which is important to suppress Pax6 activity and thus breaks pax6 autoregulation at defined steps during the formation of the visual system.

scholarly journals Long noncoding RNA FER1L4 promotes the malignant processes of papillary thyroid cancer by targeting the miR-612/ Cadherin 4 axis

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Luyao Wu ◽  
Yu Ding ◽  
Houchao Tong ◽  
Xi Zhuang ◽  
Jingsheng Cai ◽  
...  
Keyword(s):  
Thyroid Cancer ◽  
Papillary Thyroid Cancer ◽  
Noncoding Rna ◽  
Animal Experiments ◽  
Ectopic Expression ◽  
Luciferase Reporter ◽  
Migration And Invasion ◽  
Papillary Thyroid ◽  
Loss Of Function ◽  
Functional Roles

Abstract Background Long noncoding RNAs (lncRNAs) have emerged as crucial regulators in various cancers. However, the functional roles of most lncRNA in papillary thyroid cancer (PTC) are not detailly understood. This study aims to investigate the biological function and molecular mechanism of lncRNA Fer-1 like family member 4 (FER1L4) in PTC. Methods The expression of FER1L4 in PTC was determined via operating quantitative real-time PCR assays. Meanwhile, the clinical significance of FER1L4 in patients with PTC was described. The biological functions of FER1L4 on PTC cells were evaluated by gain and loss of function experiments. Moreover, animal experiments were performed to reveal the effect on tumor growth. Subcellular distribution of FER1L4 was determined by fluorescence in situ hybridization and subcellular localization assays. Luciferase reporter assay and RNA immunoprecipitation assay were applied to define the relationship between FER1L4, miR-612, and Cadherin 4 (CDH4). Results Upregulated expression of FER1L4 in PTC tissues was positively correlated with lymph node metastasis (P = 0.020), extrathyroidal extension (P = 0.013) and advanced TNM stages (P = 0.013). In addition, knockdown of FER1L4 suppressed PTC cell proliferation, migration, and invasion, whereas ectopic expression of FER1L4 inversely promoted these processes. Mechanistically, FER1L4 could competitively bind with miR-612 to prevent the degradation of its target gene CDH4. This condition was further confirmed in the rescue assays. Conclusions This study first demonstrates FER1L4 plays an oncogenic role in PTC via a FER1L4-miR-612-CDH4 axis and may provide new therapeutic and diagnostic targets for PTC.

scholarly journals Cyclovirobuxine D Induced-Mitophagy through the p65/BNIP3/LC3 Axis Potentiates Its Apoptosis-Inducing Effects in Lung Cancer Cells

2021 ◽  
Vol 22 (11) ◽  
pp. 5820
Author(s):  
Cheng Zeng ◽  
Tingting Zou ◽  
Junyan Qu ◽  
Xu Chen ◽  
Suping Zhang ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Cancer Cells ◽  
Transcriptional Repression ◽  
Therapeutic Strategy ◽  
Ectopic Expression ◽  
Lung Cancer Cells ◽  
Lung Cancer Patients ◽  
Cellular Context ◽  
Subcutaneous Xenograft ◽  
Buxus Microphylla

Mitophagy plays a pro-survival or pro-death role that is cellular-context- and stress-condition-dependent. In this study, we revealed that cyclovirobuxine D (CVB-D), a natural compound derived from Buxus microphylla, was able to provoke mitophagy in lung cancer cells. CVB-D-induced mitophagy potentiates apoptosis by promoting mitochondrial dysfunction. Mechanistically, CVB-D initiates mitophagy by enhancing the expression of the mitophagy receptor BNIP3 and strengthening its interaction with LC3 to provoke mitophagy. Our results further showed that p65, a transcriptional suppressor of BNIP3, is downregulated upon CVB-D treatment. The ectopic expression of p65 inhibits BNIP3 expression, while its knockdown significantly abolishes its transcriptional repression on BNIP3 upon CVB-D treatment. Importantly, nude mice bearing subcutaneous xenograft tumors presented retarded growth upon CVB-D treatment. Overall, we demonstrated that CVB-D treatment can provoke mitophagy and further revealed that the p65/BNIP3/LC3 axis is one potential mechanism involved in CVB-D-induced mitophagy in lung cancer cells, thus providing an effective antitumor therapeutic strategy for the treatment of lung cancer patients

scholarly journals Partitioning of N-Ethylmaleimide-Sensitive Fusion (NSF) Protein Function in Drosophila melanogaster: dNSF1 Is Required in the Nervous System, and dNSF2 Is Required in Mesoderm

Genetics ◽  
2001 ◽  
Vol 158 (1) ◽  
pp. 265-278
Author(s):  
Jessica A Golby ◽  
Leigh Anna Tolar ◽  
Leo Pallanck
Keyword(s):  
Nervous System ◽  
Protein Function ◽  
Ectopic Expression ◽  
Drosophila Genome ◽  
Loss Of Function ◽  
Stage Of Development ◽  
Expression Studies ◽  
Larval Nervous System ◽  
Constitutive Secretion ◽  
Temporal And Spatial

Abstract The N-ethylmaleimide-sensitive fusion protein (NSF) promotes the fusion of secretory vesicles with target membranes in both regulated and constitutive secretion. While it is thought that a single NSF may perform this function in many eukaryotes, previous work has shown that the Drosophila genome contains two distinct NSF genes, dNSF1 and dNSF2, raising the possibility that each plays a specific secretory role. To explore this possibility, we generated mutations in the dNSF2 gene and used these and novel dNSF1 loss-of-function mutations to analyze the temporal and spatial requirements and the degree of functional redundancy between dNSF1 and dNSF2. Results of this analysis indicate that dNSF1 function is required in the nervous system beginning at the adult stage of development and that dNSF2 function is required in mesoderm beginning at the first instar larval stage of development. Additional evidence suggests that dNSF1 and dNSF2 may play redundant roles during embryonic development and in the larval nervous system. Ectopic expression studies demonstrate that the dNSF1 and dNSF2 gene products can functionally substitute for one another. These results indicate that the Drosophila NSF proteins exhibit similar functional properties, but have evolved distinct tissue-specific roles.

scholarly journals Polyamine-modulated c-Myc expression in normal intestinal epithelial cells regulates p21Cip1 transcription through a proximal promoter region

2006 ◽  
Vol 398 (2) ◽  
pp. 257-267 ◽  
Author(s):  
Lan Liu ◽  
Xin Guo ◽  
Jaladanki N. Rao ◽  
Tongtong Zou ◽  
Bernard S. Marasa ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Transcriptional Repression ◽  
Critical Role ◽  
Ectopic Expression ◽  
Proximal Region ◽  
Proximal Promoter ◽  
Transcriptional Level ◽  
Intestinal Epithelial ◽  
Major Player ◽  
Stimulation Of

Maintenance of intestinal mucosal epithelial integrity requires cellular polyamines that regulate expression of various genes involved in cell proliferation, growth arrest and apoptosis. Our previous studies have shown that polyamines are essential for expression of the c-myc gene and that polyamine-induced c-Myc plays a critical role in stimulation of normal IEC (intestinal epithelial cell) proliferation, but the exact downstream targets of induced c-Myc are still unclear. The p21Cip1 protein is a major player in cell cycle control, which is primarily regulated at the transcriptional level. The current study was designed to determine whether induced c-Myc stimulates normal IEC proliferation by repressing p21Cip1 transcription following up-regulation of polyamines. Overexpression of the ODC (ornithine decarboxylase) gene increased levels of cellular polyamines, induced c-Myc expression and inhibited p21Cip1 transcription, as indicated by repression of p21Cip1 promoter activity and a decrease in p21Cip1 protein levels. In contrast, depletion of cellular polyamines by inhibiting ODC enzyme activity with α-difluoromethylornithine decreased c-Myc, but increased p21Cip1 transcription. Ectopic expression of wild-type c-myc not only inhibited basal levels of p21Cip1 transcription in control cells, but also prevented increased p21Cip1 in polyamine-deficient cells. Experiments using different p21Cip1 promoter mutants showed that transcriptional repression of p21Cip1 by c-Myc was mediated through Miz-1- and Sp1-binding sites within the proximal region of the p21Cip1 promoter in normal IECs. These findings confirm that p21Cip1 is one of the direct mediators of induced c-Myc following increased polyamines and that p21Cip1 repression by c-Myc is implicated in stimulation of normal IEC proliferation.

The Xenopus homologue of the Drosophila gene tailless has a function in early eye development

Development ◽  
1998 ◽  
Vol 125 (13) ◽  
pp. 2425-2432 ◽  
Author(s):  
T. Hollemann ◽  
E. Bellefroid ◽  
T. Pieler
Keyword(s):  
Eye Development ◽  
Neural Plate ◽  
Regulatory Function ◽  
Genetic Circuits ◽  
Optic Stalk ◽  
Drosophila Gene ◽  
Ciliary Margin ◽  
Evolutionarily Conserved ◽  
Optic Cup ◽  
Vertebrate Eye

Genetic circuits responsible for the development of photoreceptive organs appear to be evolutionarily conserved. Here, the Xenopus homologue Xtll of the Drosophila gene tailless (tll), which we find to be expressed during early eye development, is characterized with respect to its relationship to vertebrate regulators of eye morphogenesis, such as Pax6 and Rx. Expression of all three genes is first detected in the area corresponding to the eye anlagen within the open neural plate in partially overlapping, but not identical, patterns. During the evagination of the optic vesicle, Xtll expression is most prominent in the optic stalk, as well as in the distal tip of the forming vesicle. In tadpole-stage embryos, Xtll gene transcription is most prominent in the ciliary margin of the optic cup. Inhibition of Xtll function in Xenopus embryos interferes specifically with the evagination of the eye vesicle and, in consequence, Xpax6 gene expression is severely reduced in such manipulated embryos. These findings suggest that Xtll serves an important regulatory function in the earliest phases of vertebrate eye development.

The upstream ectoderm enhancer in Pax6 has an important role in lens induction

Development ◽  
2001 ◽  
Vol 128 (22) ◽  
pp. 4415-4424 ◽  
Author(s):  
Patricia V. Dimanlig ◽  
Sonya C. Faber ◽  
Woytek Auerbach ◽  
Helen P. Makarenkova ◽  
Richard A. Lang
Keyword(s):  
Transcriptional Control ◽  
Control Element ◽  
Pax6 Gene ◽  
Pax6 Expression ◽  
Surface Ectoderm ◽  
Targeted Deletion ◽  
Lens Vesicle ◽  
Normal Lens ◽  
Lens Formation ◽  
Lens Placode

The Pax6 gene has a central role in development of the eye. We show, through targeted deletion in the mouse, that an ectoderm enhancer in the Pax6 gene is required for normal lens formation. Ectoderm enhancer-deficient embryos exhibit distinctive defects at every stage of lens development. These include a thinner lens placode, reduced placodal cell proliferation, and a small lens pit and lens vesicle. In addition, the lens vesicle fails to separate from the surface ectoderm and the maturing lens is smaller and shows a delay in fiber cell differentiation. Interestingly, deletion of the ectoderm enhancer does not eliminate Pax6 production in the lens placode but results in a diminished level that, in central sections, is apparent primarily on the nasal side. This argues that Pax6 expression in the lens placode is controlled by the ectoderm enhancer and at least one other transcriptional control element. It also suggests that Pax6 enhancers active in the lens placode drive expression in distinct subdomains, an assertion that is supported by the expression pattern of a lacZ reporter transgene driven by the ectoderm enhancer. Interestingly, deletion of the ectoderm enhancer causes loss of expression of Foxe3, a transcription factor gene mutated in the dysgenetic lens mouse. When combined, these data and previously published work allow us to assemble a more complete genetic pathway describing lens induction. This pathway features (1) a pre-placodal phase of Pax6 expression that is required for the activity of multiple, downstream Pax6 enhancers; (2) a later, placodal phase of Pax6 expression regulated by multiple enhancers; and (3) the Foxe3 gene in a downstream position. This pathway forms a basis for future analysis of lens induction mechanism.

Expression of the BDNF gene in the developing visual system of the chick

Development ◽  
1994 ◽  
Vol 120 (6) ◽  
pp. 1643-1649 ◽  
Author(s):  
K.H. Herzog ◽  
K. Bailey ◽  
Y.A. Barde
Keyword(s):  
Visual System ◽  
Ganglion Cells ◽  
Mrna Levels ◽  
Retinal Ganglion ◽  
Bdnf Gene ◽  
Bdnf Mrna ◽  
Optic Stalk ◽  
Copy Numbers ◽  
Activity Dependent

Using a sensitive and quantitative method, the mRNA levels of brain-derived neurotrophic factor (BDNF) were determined during the development of the chick visual system. Low copy numbers were detected, and BDNF was found to be expressed in the optic tectum already 2 days before the arrival of the first retinal ganglion cell axons, suggesting an early role of BDNF in tectal development. After the beginning of tectal innervation, BDNF mRNA levels markedly increased, and optic stalk transection at day 4 (which prevents subsequent tectal innervation) was found to reduce the contralateral tectal levels of BDNF mRNA. Comparable reductions were obtained after injection of tetrodotoxin into one eye, indicating that, already during the earliest stages of target encounter in the CNS, the degree of BDNF gene expression is influenced by activity-dependent mechanisms. BDNF mRNA was also detected in the retina itself and at levels comparable to those found in the tectum. Together with previous findings indicating that BDNF prevents the death of cultured chick retinal ganglion cells, these results support the idea that the tightly controlled expression of the BDNF gene might be important in the co-ordinated development of the visual system.

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