Leafbladeless1 is required for dorsoventrality of lateral organs in maize

Development ◽  
1998 ◽  
Vol 125 (15) ◽  
pp. 2813-2823 ◽  
Author(s):  
M.C. Timmermans ◽  
N.P. Schultes ◽  
J.P. Jankovsky ◽  
T. Nelson
Keyword(s):  
Leaf Development ◽  
Homeobox Gene ◽  
Cell Types ◽  
Partial Loss ◽  
Cell Identity ◽  
Cell Recruitment ◽  
Lateral Organs ◽  
Lateral Organ ◽  
Complete Duplication ◽  
Lateral Propagation

The maize leafbladeless1 (lbl1) mutant displays a variety of leaf and plant phenotypes. The most extreme manifestation in the leaf is the formation of radially symmetric, abaxialized leaves due to a complete loss of adaxial cell types. Less severe phenotypes, resulting from a partial loss of adaxial cell identity, include the formation of ectopic laminae at the boundary between abaxialized, mutant sectors on the adaxial leaf surface and the bifurcation of leaves. Ectopic laminae and bifurcations arise early in leaf development and result in an altered patterning of the leaf along the proximodistal axis, or in complete duplication of the developing organ. Leaf-like lateral organs of the inflorescences and flowers show similar phenotypes. These observations suggest that Lbl1 is required for the specification of adaxial cell identity within leaves and leaf-like lateral organs. Lbl1 is also required for the lateral propagation of leaf founder cell recruitment, and plays a direct or indirect role in the downregulation of the homeobox gene, knotted1, during leaf development. Our results suggest that adaxial/abaxial asymmetry of lateral organs is specified in the shoot apical meristem, and that formation of this axis is essential for marginal, lateral growth and for the specification of points of proximodistal growth. Parallels between early patterning events during lateral organ development in plants and animals are discussed.

scholarly journals phantastica: a gene required for dorsoventrality of leaves in Antirrhinum majus

Development ◽  
1995 ◽  
Vol 121 (7) ◽  
pp. 2143-2154 ◽  
Author(s):  
R. Waites ◽  
A. Hudson
Keyword(s):  
Cell Types ◽  
Antirrhinum Majus ◽  
Lateral Growth ◽  
Wild Type ◽  
Cell Identity ◽  
Lateral Organs ◽  
Floral Phenotype

To understand better the mechanisms that lead to dorsoventrality in the lateral organs of plants, mutants at the phantastica (phan) locus of Antirrhinum majus have been identified and characterised. The leaves, bracts and petal lobes of phan mutants show varying degrees of reduction in dorsal tissues, indicating that phan is required for establishing dorsal cell identity. Each phan mutant produces a variety of different leaf morphologies, but has a characteristic and relatively constant floral phenotype. In several different forms of phan mutant leaves and petal lobes, novel boundaries between dorsal and ventral cell types form ectopic axes of growth, suggesting that phan-dependent dorsal cell identity is required for lateral growth of the wild-type leaf and petal lobe. Comparisons between the development of wild-type and mutant petals or leaves reveal that phan acts early in development of these lateral organs. The possible role of the phan gene in evolution of different leaf forms is discussed.

scholarly journals Expression of maize KNOTTED1 related homeobox genes in the shoot apical meristem predicts patterns of morphogenesis in the vegetative shoot

Development ◽  
1994 ◽  
Vol 120 (2) ◽  
pp. 405-413 ◽  
Author(s):  
D. Jackson ◽  
B. Veit ◽  
S. Hake
Keyword(s):  
Shoot Apical Meristem ◽  
Leaf Development ◽  
Apical Meristem ◽  
Expression Patterns ◽  
Homeobox Genes ◽  
Homeobox Gene ◽  
Vegetative Shoot ◽  
Lateral Organs ◽  
Floral Meristems ◽  
Shoot Meristems

In this paper we describe the expression patterns of a family of homeobox genes in maize and their relationship to organogenic domains in the vegetative shoot apical meristem. These genes are related by sequence to KNOTTED1, a gene characterized by dominant neomorphic mutations which perturb specific aspects of maize leaf development. Four members of this gene family are expressed in shoot meristems and the developing stem, but not in determinate lateral organs such as leaves or floral organs. The genes show distinct expression patterns in the vegetative shoot apical meristem that together predict the site of leaf initiation and the basal limit of the vegetative ‘phytomer’ or segmentation unit of the shoot. These genes are also expressed in the inflorescence and floral meristems, where their patterns of expression are more similar, and they are not expressed in root apical meristems. These findings are discussed in relation to other studies of shoot apical meristem organization as well as possible commonality of homeobox gene function in the animal and plant kingdoms.

scholarly journals Signaling Control of Mucociliary Epithelia: Stem Cells, Cell Fates, and the Plasticity of Cell Identity in Development and Disease

2021 ◽  
pp. 1-18
Author(s):  
Peter Walentek
Keyword(s):  
Stem Cells ◽  
Mucociliary Clearance ◽  
Cell Types ◽  
Secretory Cells ◽  
Chronic Obstructive ◽  
Cell Identity ◽  
Obstructive Pulmonary Disease ◽  
Congenital Diseases ◽  
Inhaled Particles ◽  
Mucociliary Epithelia

Mucociliary epithelia are composed of multiciliated, secretory, and stem cells and line various organs in vertebrates such as the respiratory tract. By means of mucociliary clearance, those epithelia provide a first line of defense against inhaled particles and pathogens. Mucociliary clearance relies on the correct composition of cell types, that is, the proper balance of ciliated and secretory cells. A failure to generate and to maintain correct cell type composition and function results in impaired clearance and high risk to infections, such as in congenital diseases (e.g., ciliopathies) as well as in acquired diseases, including asthma, chronic obstructive pulmonary disease (COPD), and idiopathic pulmonary fibrosis (IPF). While it remains incompletely resolved how precisely cell types are specified and maintained in development and disease, many studies have revealed important mechanisms regarding the signaling control in mucociliary cell types in various species. Those studies not only provided insights into the signaling contribution to organ development and regeneration but also highlighted the remarkable plasticity of cell identity encountered in mucociliary maintenance, including frequent trans-differentiation events during homeostasis and specifically in disease. This review will summarize major findings and provide perspectives regarding the future of mucociliary research and the treatment of chronic airway diseases associated with tissue remodeling.

scholarly journals Histone Acetyltransferases and Stem Cell Identity

Cancers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 2407
Author(s):  
Ruicen He ◽  
Arthur Dantas ◽  
Karl Riabowol
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Cell Fate ◽  
Epigenetic Modification ◽  
Cell Types ◽  
Histone Acetyltransferases ◽  
Specific Cell ◽  
Cell Fates ◽  
Cell Identity ◽  
Hematopoietic Stem

Acetylation of histones is a key epigenetic modification involved in transcriptional regulation. The addition of acetyl groups to histone tails generally reduces histone-DNA interactions in the nucleosome leading to increased accessibility for transcription factors and core transcriptional machinery to bind their target sequences. There are approximately 30 histone acetyltransferases and their corresponding complexes, each of which affect the expression of a subset of genes. Because cell identity is determined by gene expression profile, it is unsurprising that the HATs responsible for inducing expression of these genes play a crucial role in determining cell fate. Here, we explore the role of HATs in the maintenance and differentiation of various stem cell types. Several HAT complexes have been characterized to play an important role in activating genes that allow stem cells to self-renew. Knockdown or loss of their activity leads to reduced expression and or differentiation while particular HATs drive differentiation towards specific cell fates. In this study we review functions of the HAT complexes active in pluripotent stem cells, hematopoietic stem cells, muscle satellite cells, mesenchymal stem cells, neural stem cells, and cancer stem cells.

scholarly journals A nervous system-specific subnuclear organelle in Caenorhabditis elegans

Genetics ◽  
2021 ◽  
Vol 217 (1) ◽  
Author(s):  
Kenneth Pham ◽  
Neda Masoudi ◽  
Eduardo Leyva-Díaz ◽  
Oliver Hobert
Keyword(s):  
Nervous System ◽  
Caenorhabditis Elegans ◽  
Homeobox Gene ◽  
Cell Types ◽  
Nuclear Bodies ◽  
Loss Of Function ◽  
Cell Type ◽  
Cell Type Specificity ◽  
Splicing Speckles ◽  
Polycomb Bodies

Abstract We describe here phase-separated subnuclear organelles in the nematode Caenorhabditis elegans, which we term NUN (NUclear Nervous system-specific) bodies. Unlike other previously described subnuclear organelles, NUN bodies are highly cell type specific. In fully mature animals, 4–10 NUN bodies are observed exclusively in the nucleus of neuronal, glial and neuron-like cells, but not in other somatic cell types. Based on co-localization and genetic loss of function studies, NUN bodies are not related to other previously described subnuclear organelles, such as nucleoli, splicing speckles, paraspeckles, Polycomb bodies, promyelocytic leukemia bodies, gems, stress-induced nuclear bodies, or clastosomes. NUN bodies form immediately after cell cycle exit, before other signs of overt neuronal differentiation and are unaffected by the genetic elimination of transcription factors that control many other aspects of neuronal identity. In one unusual neuron class, the canal-associated neurons, NUN bodies remodel during larval development, and this remodeling depends on the Prd-type homeobox gene ceh-10. In conclusion, we have characterized here a novel subnuclear organelle whose cell type specificity poses the intriguing question of what biochemical process in the nucleus makes all nervous system-associated cells different from cells outside the nervous system.

PAX2 is expressed in multiple spinal cord interneurons, including a population of EN1+ interneurons that require PAX6 for their development

Development ◽  
1997 ◽  
Vol 124 (22) ◽  
pp. 4493-4503 ◽  
Author(s):  
J.D. Burrill ◽  
L. Moran ◽  
M.D. Goulding ◽  
H. Saueressig
Keyword(s):  
Spinal Cord ◽  
Transcription Factors ◽  
Ventricular Zone ◽  
Cell Types ◽  
Cell Identity ◽  
Patterning Genes ◽  
Postmitotic Neurons ◽  
Pax Family ◽  
Early Activity

Members of the PAX family of transcription factors are candidates for controlling cell identity in the spinal cord. We have morphologically analyzed cells that express one of these transcription factors, PAX2, demonstrating multiple interneuron cell types express PAX2. Two ventral populations of PAX2-expressing interneurons in the spinal cord are marked by coexpression of the transcription factors, EN1 and EVX1. Interestingly, the expression domains of PAX2, EN1 and EVX1 in postmitotic neurons correlate closely with those of Pax6 and Pax7 in the ventricular zone, implicating these patterning genes in the regulation of PAX2, EN1 and EVX1. We show that one of these patterning genes, Pax6, is required for the correct specification of ventral PAX2+ interneurons that coexpress EN1. These results demonstrate that the early activity of patterning genes in the ventricular zone determines interneuron identity in the spinal cord.

BMP signaling patterns the dorsal and intermediate neural tube via regulation of homeobox and helix-loop-helix transcription factors

Development ◽  
2002 ◽  
Vol 129 (10) ◽  
pp. 2459-2472 ◽  
Author(s):  
John R. Timmer ◽  
Charlotte Wang ◽  
Lee Niswander
Keyword(s):  
Transcription Factors ◽  
Neural Tube ◽  
Transforming Growth Factor ◽  
Cell Types ◽  
Neural Cell ◽  
Bmp Signaling ◽  
Expression Domain ◽  
Cell Identity ◽  
Dorsoventral Axis ◽  
Helix Loop Helix

In the spinal neural tube, populations of neuronal precursors that express a unique combination of transcription factors give rise to specific classes of neurons at precise locations along the dorsoventral axis. Understanding the patterning mechanisms that generate restricted gene expression along the dorsoventral axis is therefore crucial to understanding the creation of diverse neural cell types. Bone morphogenetic proteins (BMPs) and other transforming growth factor β (TGFβ) proteins are expressed by the dorsal-most cells of the neural tube (the roofplate) and surrounding tissues, and evidence indicates that they play a role in assigning cell identity. We have manipulated the level of BMP signaling in the chicken neural tube to show that BMPs provide patterning information to both dorsal and intermediate cells. BMP regulation of the expression boundaries of the homeobox proteins Pax6, Dbx2 and Msx1 generates precursor populations with distinct developmental potentials. Within the resulting populations, thresholds of BMP act to set expression domain boundaries of developmental regulators of the homeobox and basic helix-loop-helix (bHLH) families, ultimately leading to the generation of a diversity of differentiated neural cell types. This evidence strongly suggests that BMPs are the key regulators of dorsal cell identity in the spinal neural tube.

scholarly journals Disruption of Broad Epigenetic Domains in PDAC Cells by HAT Inhibitors

Epigenomes ◽  
2019 ◽  
Vol 3 (2) ◽  
pp. 11 ◽  
Author(s):  
Diana L. Gerrard ◽  
Joseph R. Boyd ◽  
Gary S. Stein ◽  
Victor X. Jin ◽  
Seth Frietze
Keyword(s):  
Pancreatic Cancer ◽  
Expression Patterns ◽  
Genomic Analysis ◽  
Cell Types ◽  
Ductal Adenocarcinoma ◽  
Global Changes ◽  
Low Grade ◽  
Cell Identity ◽  
Pancreatic Cancer Cells ◽  
Epithelial Phenotype

The spreading of epigenetic domains has emerged as a distinguishing epigenomic phenotype for diverse cell types. In particular, clusters of H3K27ac- and H3K4me3-marked elements, referred to as super-enhancers, and broad H3K4me3 domains, respectively, have been linked to cell identity and disease states. Here, we characterized the broad domains from different pancreatic ductal adenocarcinoma (PDAC) cell lines that represent distinct histological grades. Our integrative genomic analysis found that human derived cell line models for distinct PDAC grades exhibit characteristic broad epigenetic features associated with gene expression patterns that are predictive of patient prognosis and provide insight into pancreatic cancer cell identity. In particular, we find that genes marked by overlapping Low-Grade broad domains correspond to an epithelial phenotype and hold potential as markers for patient stratification. We further utilize ChIP-seq to compare the effects of histone acetyltransferase (HAT) inhibitors to detect global changes in histone acetylation and methylation levels. We found that HAT inhibitors impact certain broad domains of pancreatic cancer cells. Overall, our results reveal potential roles for broad domains in cells from distinct PDAC grades and demonstrate the plasticity of particular broad epigenomic domains to epigenetic inhibitors.

scholarly journals A Highly Active Homeobox Gene Promoter Regulated by Ets and Sp1 Family Members in Normal Granulosa Cells and Diverse Tumor Cell Types

2002 ◽  
Vol 277 (29) ◽  
pp. 26036-26045 ◽  
Author(s):  
Manjeet K. Rao ◽  
Sourindra Maiti ◽  
Honnavara N. Ananthaswamy ◽  
Miles F. Wilkinson
Keyword(s):  
Tumor Cell ◽  
Granulosa Cells ◽  
Family Members ◽  
Homeobox Gene ◽  
Gene Promoter ◽  
Cell Types ◽  
Highly Active

scholarly journals Single-nucleus RNA-seq reveals dysregulation of striatal cell identity due to Huntington’s disease mutations

2020 ◽  
Author(s):  
Sonia Malaiya ◽  
Marcia Cortes-Gutierrez ◽  
Brian R. Herb ◽  
Sydney R. Coffey ◽  
Samuel R.W. Legg ◽  
...  
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Neurodegenerative Disorder ◽  
Cell Types ◽  
Transcriptional Networks ◽  
Rna Seq ◽  
Cell Type ◽  
Cell Identity ◽  
Transcriptional Changes ◽  
Cell Type Specific

ABSTRACTHuntington’s disease (HD) is a dominantly inherited neurodegenerative disorder caused by a trinucleotide expansion in exon 1 of the huntingtin (Htt) gene. Cell death in HD occurs primarily in striatal medium spiny neurons (MSNs), but the involvement of specific MSN subtypes and of other striatal cell types remains poorly understood. To gain insight into cell type-specific disease processes, we studied the nuclear transcriptomes of 4,524 cells from the striatum of a genetically precise knock-in mouse model of the HD mutation, HttQ175/+, and from wildtype controls. We used 14-15-month-old mice, a time point roughly equivalent to an early stage of symptomatic human disease. Cell type distributions indicated selective loss of D2 MSNs and increased microglia in aged HttQ175/+ mice. Thousands of differentially expressed genes were distributed across most striatal cell types, including transcriptional changes in glial populations that are not apparent from RNA-seq of bulk tissue. Reconstruction of cell typespecific transcriptional networks revealed a striking pattern of bidirectional dysregulation for many cell type-specific genes. Typically, these genes were repressed in their primary cell type, yet de-repressed in other striatal cell types. Integration with existing epigenomic and transcriptomic data suggest that partial loss-of-function of the Polycomb Repressive Complex 2 (PRC2) may underlie many of these transcriptional changes, leading to deficits in the maintenance of cell identity across virtually all cell types in the adult striatum.

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