The Sox-domain containing geneDichaete/fish-hookacts in concert withvndandindto regulate cell fate in theDrosophilaneuroectoderm

Development ◽  
2002 ◽  
Vol 129 (5) ◽  
pp. 1165-1174 ◽  
Author(s):  
Guoyan Zhao ◽  
James B. Skeath

In the Drosophila embryonic central nervous system, neural stem cells, called neuroblasts, acquire fates in a position-specific manner. Recent work has identified a set of genes that functions along the dorsoventral axis to enable neuroblasts that develop in different dorsoventral domains to acquire distinct fates. These genes include the evolutionarily conserved transcription factors ventral nerve cord defective and intermediate neuroblasts defective, as well as the Drosophila EGF receptor. We show that the Sox-domain-containing gene Dichaete/fish-hook also plays a crucial role to pattern the neuroectoderm along the DV axis. Dichaete is expressed in the medial and intermediate columns of the neuroectoderm, and mutant analysis indicates that Dichaete regulates cell fate and neuroblast formation in these domains. Molecular epistasis tests, double mutant analysis and dosage-sensitive interactions demonstrate that during these processes, Dichaete functions in parallel with ventral nerve cord defective and intermediate neuroblasts defective, and downstream of EGF receptor signaling to mediate its effect on development. These results identify Dichaete as an important regulator of dorsoventral pattern in the neuroectoderm, and indicate that Dichaete acts in concert with ventral nerve cord defective and intermediate neuroblasts defective to regulate pattern and cell fate in the neuroectoderm.

2019 ◽  
Vol 11 (11) ◽  
pp. 994-1005 ◽  
Author(s):  
Ran Wei ◽  
Xuguang Liu ◽  
Courtney Voss ◽  
Wentao Qin ◽  
Lina Dagnino ◽  
...  

Abstract NUMB is an evolutionarily conserved protein that plays an important role in cell adhesion, migration, polarity, and cell fate determination. It has also been shown to play a role in the pathogenesis of certain cancers, although it remains controversial whether NUMB functions as an oncoprotein or tumor suppressor. Here, we show that NUMB binds to anaplastic lymphoma kinase (ALK), a receptor tyrosine kinase aberrantly activated in several forms of cancer, and this interaction regulates the endocytosis and activity of ALK. Intriguingly, the function of the NUMB–ALK interaction is isoform-dependent. While both p66-NUMB and p72-NUMB isoforms are capable of mediating the endocytosis of ALK, the former directs ALK to the lysosomal degradation pathway, thus decreasing the overall ALK level and the downstream MAP kinase signal. In contrast, the p72-NUMB isoform promotes ALK recycling back to the plasma membrane, thereby maintaining the kinase in its active state. Our work sheds light on the controversial role of different isoforms of NUMB in tumorigenesis and provides mechanistic insight into ALK regulation.


Development ◽  
2000 ◽  
Vol 127 (17) ◽  
pp. 3769-3776 ◽  
Author(s):  
K. Kubota ◽  
S. Goto ◽  
K. Eto ◽  
S. Hayashi

Wing and leg precursors of Drosophila are recruited from a common pool of ectodermal cells expressing the homeobox gene Dll. Induction by Dpp promotes this cell fate decision toward the wing and proximal leg. We report here that the receptor tyrosine kinase EGFR antagonizes the wing-promoting function of Dpp and allows recruitment of leg precursor cells from uncommitted ectodermal cells. By monitoring the spatial distribution of cells responding to Dpp and EGFR, we show that nuclear transduction of the two signals peaks at different position along the dorsoventral axis when the fates of wing and leg discs are specified and that the balance of the two signals assessed within the nucleus determines the number of cells recruited to the wing. Differential activation of the two signals and the cross talk between them critically affect this cell fate choice.


Development ◽  
1997 ◽  
Vol 124 (13) ◽  
pp. 2515-2525 ◽  
Author(s):  
R. Dittrich ◽  
T. Bossing ◽  
A.P. Gould ◽  
G.M. Technau ◽  
J. Urban

The Drosophila ventral nerve cord (vNC) derives from a stereotyped population of neural stem cells, neuroblasts (NBs), each of which gives rise to a characteristic cell lineage. The mechanisms leading to the specification and differentiation of these lineages are largely unknown. Here we analyse mechanisms leading to cell differentiation within the NB 7–3 lineage. Analogous to the grasshopper, NB 7–3 is the progenitor of the Drosophila vNC serotonergic neurons. The zinc finger protein Eagle (Eg) is expressed in NB 7–3 just after delamination and is present in all NB 7–3 progeny until late stage 17. DiI cell lineage tracing and immunocytochemistry reveal that eg is required for normal pathfinding of interneuronal projections and for restricting the cell number in the thoracic NB 7–3 lineage. Moreover, eg is required for serotonin expression. Ectopic expression of Eg protein forces specific additional CNS cells to enter the serotonergic differentiation pathway. Like NB 7–3, the progenitor(s) of these ectopic cells express Huckebein (Hkb), another zinc finger protein. However, their progenitors do not express engrailed (en) as opposed to the NB 7–3 lineage, where en acts upstream of eg. We conclude that eg and hkb act in concert to determine serotonergic cell fate, while en is more distantly involved in this process by activating eg expression. Thus, we provide the first functional evidence for a combinatorial code of transcription factors acting early but downstream of segment polarity genes to specify a unique neuronal cell fate.


Author(s):  
Roy J. Baerwald ◽  
Lura C. Williamson

In arthropods the perineurium surrounds the neuropile, consists of modified glial cells, and is the morphological basis for the blood-brain barrier. The perineurium is surrounded by an acellular neural lamella, sometimes containing scattered collagen-like fibrils. This perineurial-neural lamellar complex is thought to occur ubiquitously throughout the arthropods. This report describes a SEM and TEM study of the sheath surrounding the ventral nerve cord of Panulirus argus.Juvenile P. argus were collected from the Florida Keys and maintained in marine aquaria. Nerve cords were fixed for TEM in Karnovsky's fixative and saturated tannic acid in 0.1 M Na-cacodylate buffer, pH = 7.4; post-fixed in 1.0% OsO4 in the same buffer; dehydrated through a graded series of ethanols; embedded in Epon-Araldite; and examined in a Philips 200 TEM. Nerve cords were fixed for SEM in a similar manner except that tannic acid was not used.


Metabolites ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 80
Author(s):  
Joohwan Kim ◽  
Gina Lee

Nutrients and metabolic pathways regulate cell growth and cell fate decisions via epigenetic modification of DNA and histones. Another key genetic material, RNA, also contains diverse chemical modifications. Among these, N6-methyladenosine (m6A) is the most prevalent and evolutionarily conserved RNA modification. It functions in various aspects of developmental and disease states, by controlling RNA metabolism, such as stability and translation. Similar to other epigenetic processes, m6A modification is regulated by specific enzymes, including writers (methyltransferases), erasers (demethylases), and readers (m6A-binding proteins). As this is a reversible enzymatic process, metabolites can directly influence the flux of this reaction by serving as substrates and/or allosteric regulators. In this review, we will discuss recent understanding of the regulation of m6A RNA modification by metabolites, nutrients, and cellular metabolic pathways.


Genetics ◽  
2001 ◽  
Vol 157 (4) ◽  
pp. 1611-1622 ◽  
Author(s):  
Go Shioi ◽  
Michinari Shoji ◽  
Masashi Nakamura ◽  
Takeshi Ishihara ◽  
Isao Katsura ◽  
...  

Abstract Using a pan-neuronal GFP marker, a morphological screen was performed to detect Caenorhabditis elegans larval lethal mutants with severely disorganized major nerve cords. We recovered and characterized 21 mutants that displayed displacement or detachment of the ventral nerve cord from the body wall (Ven: ventral cord abnormal). Six mutations defined three novel genetic loci: ven-1, ven-2, and ven-3. Fifteen mutations proved to be alleles of previously identified muscle attachment/positioning genes, mup-4, mua-1, mua-5, and mua-6. All the mutants also displayed muscle attachment/positioning defects characteristic of mua/mup mutants. The pan-neuronal GFP marker also revealed that mutants of other mua/mup loci, such as mup-1, mup-2, and mua-2, exhibited the Ven defect. The hypodermis, the excretory canal, and the gonad were morphologically abnormal in some of the mutants. The pleiotropic nature of the defects indicates that ven and mua/mup genes are required generally for the maintenance of attachment of tissues to the body wall in C. elegans.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yildiz Koca ◽  
Benjamin E. Housden ◽  
William J. Gault ◽  
Sarah J. Bray ◽  
Marek Mlodzik

AbstractIn all metazoans, a small number of evolutionarily conserved signaling pathways are reiteratively used during development to orchestrate critical patterning and morphogenetic processes. Among these, Notch (N) signaling is essential for most aspects of tissue patterning where it mediates the communication between adjacent cells to control cell fate specification. In Drosophila, Notch signaling is required for several features of eye development, including the R3/R4 cell fate choice and R7 specification. Here we show that hypomorphic alleles of Notch, belonging to the Nfacet class, reveal a novel phenotype: while photoreceptor specification in the mutant ommatidia is largely normal, defects are observed in ommatidial rotation (OR), a planar cell polarity (PCP)-mediated cell motility process. We demonstrate that during OR Notch signaling is specifically required in the R4 photoreceptor to upregulate the transcription of argos (aos), an inhibitory ligand to the epidermal growth factor receptor (EGFR), to fine-tune the activity of EGFR signaling. Consistently, the loss-of-function defects of Nfacet alleles and EGFR-signaling pathway mutants are largely indistinguishable. A Notch-regulated aos enhancer confers R4 specific expression arguing that aos is directly regulated by Notch signaling in this context via Su(H)-Mam-dependent transcription.


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