scholarly journals Repulsion by Slit and Roundabout prevents Shotgun/E-cadherin–mediated cell adhesion during Drosophila heart tube lumen formation

2008 ◽  
Vol 182 (2) ◽  
pp. 241-248 ◽  
Author(s):  
Edgardo Santiago-Martínez ◽  
Nadine H. Soplop ◽  
Rajesh Patel ◽  
Sunita G. Kramer
Keyword(s):  
Cell Adhesion ◽  
Heart Development ◽  
Cell Junction ◽  
Loss Of Function ◽  
Heart Tube ◽  
Gain Of Function ◽  
Lumen Formation ◽  
Tube Lumen ◽  
Function Blocks ◽  
E Cadherin

During Drosophila melanogaster heart development, a lumen forms between apical surfaces of contralateral cardioblasts (CBs). We show that Slit and its receptor Roundabout (Robo) are required at CB apical domains for lumen formation. Mislocalization of Slit outside the apical domain causes ectopic lumen formation and the mislocalization of cell junction proteins, E-cadherin (E-Cad) and Enabled, without disrupting overall CB cell polarity. Ectopic lumen formation is suppressed in robo mutants, which indicates robo's requirement for this process. Genetic evidence suggests that Robo and Shotgun (Shg)/E-Cad function together in modulating CB adhesion. robo and shg/E-Cad transheterozygotes have lumen defects. In robo loss-of-function or shg/E-Cad gain-of-function embryos, lumen formation is blocked because of inappropriate CB adhesion and an accumulation of E-Cad at the apical membrane. In contrast, shg/E-Cad loss-of-function or robo gain-of-function blocks lumen formation due to a loss of CB adhesion. Our data show that Slit and Robo pathways function in lumen formation as a repulsive signal to antagonize E-Cad–mediated cell adhesion.

scholarly journals The F-BAR domain of SRGP-1 facilitates cell–cell adhesion during C. elegans morphogenesis

2010 ◽  
Vol 191 (4) ◽  
pp. 761-769 ◽  
Author(s):  
Ronen Zaidel-Bar ◽  
Michael J. Joyce ◽  
Allison M. Lynch ◽  
Kristen Witte ◽  
Anjon Audhya ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Molecular Mechanisms ◽  
Function Analysis ◽  
Membrane Dynamics ◽  
Protein Domain ◽  
Cell Junctions ◽  
Cell Junction ◽  
Loss Of Function ◽  
Bar Domain ◽  
Cell Cell

Robust cell–cell adhesion is critical for tissue integrity and morphogenesis, yet little is known about the molecular mechanisms controlling cell–cell junction architecture and strength. We discovered that SRGP-1 is a novel component of cell–cell junctions in Caenorhabditis elegans, localizing via its F-BAR (Bin1, Amphiphysin, and RVS167) domain and a flanking 200–amino acid sequence. SRGP-1 activity promotes an increase in membrane dynamics at nascent cell–cell contacts and the rapid formation of new junctions; in addition, srgp-1 loss of function is lethal in embryos with compromised cadherin–catenin complexes. Conversely, excess SRGP-1 activity leads to outward bending and projections of junctions. The C-terminal half of SRGP-1 interacts with the N-terminal F-BAR domain and negatively regulates its activity. Significantly, in vivo structure–function analysis establishes a role for the F-BAR domain in promoting rapid and robust cell adhesion during embryonic closure events, independent of the Rho guanosine triphosphatase–activating protein domain. These studies establish a new role for this conserved protein family in modulating cell–cell adhesion.

Rescuing the N-cadherin knockout by cardiac-specific expression of N- or E-cadherin

Development ◽  
2001 ◽  
Vol 128 (4) ◽  
pp. 459-469
Author(s):  
Y. Luo ◽  
M. Ferreira-Cornwell ◽  
H. Baldwin ◽  
I. Kostetskii ◽  
J. Lenox ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Heart Development ◽  
Critical Role ◽  
Embryonic Cells ◽  
Wild Type ◽  
Specific Expression ◽  
Developmental Defects ◽  
E Cadherin ◽  
Cell Cell

Cell-cell adhesion mediated by some members of the cadherin family is essential for embryonic survival. The N-cadherin-null embryo dies during mid-gestation, with multiple developmental defects. We show that N-cadherin-null embryos expressing cadherins using muscle-specific promoters, alpha- or beta-myosin heavy chain, are partially rescued. Somewhat surprisingly, either N-cadherin or E-cadherin was effective in rescuing the embryos. The rescued embryos exhibited an increased number of somites, branchial arches and the presence of forelimb buds; however, in contrast, brain development was severely impaired. In rescued animals, the aberrant yolk sac morphology seen in N-cadherin-null embryos was corrected, demonstrating that this phenotype was secondary to the cardiac defect. Dye injection studies and analysis of chimeric animals that have both wild-type and N-cadherin-null cells support the conclusion that obstruction of the cardiac outflow tract represents a major defect that is likely to be the primary cause of pericardial swelling seen in null embryos. Although rescued embryos were more developed than null embryos, they were smaller than wild-type embryos, even though the integrity of the cardiovascular system appeared normal. The smaller size of rescued embryos may be due, at least in part, to increased apoptosis observed in tissues not rescued by transgene expression, indicating that N-cadherin-mediated cell adhesion provides an essential survival signal for embryonic cells. Our data provide in vivo evidence that cadherin adhesion is essential for cell survival and for normal heart development. Our data also show that E-cadherin can functionally substitute for N-cadherin during cardiogenesis, suggesting a critical role for cadherin-mediated cell-cell adhesion, but not cadherin family member-specific signaling, at the looping stage of heart development.

622: Von Hippel-Lindau Inactivation Downregulates the Cell-Cell Adhesion Molecule E Cadherin in Renal Cancer Cells

2005 ◽  
Vol 173 (4S) ◽  
pp. 170-170
Author(s):  
Maxine G. Tran ◽  
Miguel A. Esteban ◽  
Peter D. Hill ◽  
Ashish Chandra ◽  
Tim S. O'Brien ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Cancer Cells ◽  
Renal Cancer ◽  
Adhesion Molecule ◽  
Cell Adhesion Molecule ◽  
Von Hippel Lindau ◽  
E Cadherin ◽  
Cell Cell

scholarly journals Clinical spectrum and pleiotropic nature of CDH1 germline mutations

2019 ◽  
Vol 56 (4) ◽  
pp. 199-208 ◽  
Author(s):  
Joana Figueiredo ◽  
Soraia Melo ◽  
Patrícia Carneiro ◽  
Ana Margarida Moreira ◽  
Maria Sofia Fernandes ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Gastric Cancer ◽  
Genetic Alterations ◽  
Tumour Suppressor Gene ◽  
Diffuse Gastric Cancer ◽  
Loss Of Function ◽  
Lobular Breast Cancer ◽  
Cancer Syndrome ◽  
Risk Of Cancer ◽  
E Cadherin

CDH1 encodes E-cadherin, a key protein in adherens junctions. Given that E-cadherin is involved in major cellular processes such as embryogenesis and maintenance of tissue architecture, it is no surprise that deleterious effects arise from its loss of function. E-cadherin is recognised as a tumour suppressor gene, and it is well established that CDH1 genetic alterations cause diffuse gastric cancer and lobular breast cancer—the foremost manifestations of the hereditary diffuse gastric cancer syndrome. However, in the last decade, evidence has emerged demonstrating that CDH1 mutations can be associated with lobular breast cancer and/or several congenital abnormalities, without any personal or family history of diffuse gastric cancer. To date, no genotype–phenotype correlations have been observed. Remarkably, there are reports of mutations affecting the same nucleotide but inducing distinct clinical outcomes. In this review, we bring together a comprehensive analysis of CDH1-associated disorders and germline alterations found in each trait, providing important insights into the biological mechanisms underlying E-cadherin’s pleiotropic effects. Ultimately, this knowledge will impact genetic counselling and will be relevant to the assessment of risk of cancer development or congenital malformations in CDH1 mutation carriers.

scholarly journals Gain-of-function GABRB3 variants identified in vigabatrin-hypersensitive epileptic encephalopathies

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Nathan L Absalom ◽  
Vivian W Y Liao ◽  
Kavitha Kothur ◽  
Dinesh C Indurthi ◽  
Bruce Bennetts ◽  
...  
Keyword(s):  
De Novo ◽  
Drug Effects ◽  
Receptor Expression ◽  
Aminobutyric Acid ◽  
Loss Of Function ◽  
Molecular Phenotype ◽  
Gain Of Function ◽  
Gene Encoding ◽  
Epileptic Encephalopathies ◽  
Receptor Phenotype

Abstract Variants in the GABRB3 gene encoding the β3-subunit of the γ-aminobutyric acid type A ( receptor are associated with various developmental and epileptic encephalopathies. Typically, these variants cause a loss-of-function molecular phenotype whereby γ-aminobutyric acid has reduced inhibitory effectiveness leading to seizures. Drugs that potentiate inhibitory GABAergic activity, such as nitrazepam, phenobarbital or vigabatrin, are expected to compensate for this and thereby reduce seizure frequency. However, vigabatrin, a drug that inhibits γ-aminobutyric acid transaminase to increase tonic γ-aminobutyric acid currents, has mixed success in treating seizures in patients with GABRB3 variants: some patients experience seizure cessation, but there is hypersensitivity in some patients associated with hypotonia, sedation and respiratory suppression. A GABRB3 variant that responds well to vigabatrin involves a truncation variant (p.Arg194*) resulting in a clear loss-of-function. We hypothesized that patients with a hypersensitive response to vigabatrin may exhibit a different γ-aminobutyric acid A receptor phenotype. To test this hypothesis, we evaluated the phenotype of de novo variants in GABRB3 (p.Glu77Lys and p.Thr287Ile) associated with patients who are clinically hypersensitive to vigabatrin. We introduced the GABRB3 p.Glu77Lys and p.Thr287Ile variants into a concatenated synaptic and extrasynaptic γ-aminobutyric acid A receptor construct, to resemble the γ-aminobutyric acid A receptor expression by a patient heterozygous for the GABRB3 variant. The mRNA of these constructs was injected into Xenopus oocytes and activation properties of each receptor measured by two-electrode voltage clamp electrophysiology. Results showed an atypical gain-of-function molecular phenotype in the GABRB3 p.Glu77Lys and p.Thr287Ile variants characterized by increased potency of γ-aminobutyric acid A without change to the estimated maximum open channel probability, deactivation kinetics or absolute currents. Modelling of the activation properties of the receptors indicated that either variant caused increased chloride flux in response to low concentrations of γ-aminobutyric acid that mediate tonic currents. We therefore propose that the hypersensitivity reaction to vigabatrin is a result of GABRB3 variants that exacerbate GABAergic tonic currents and caution is required when prescribing vigabatrin. In contrast, drug strategies increasing tonic currents in loss-of-function variants are likely to be a safe and effective therapy. This study demonstrates that functional genomics can explain beneficial and adverse anti-epileptic drug effects, and propose that vigabatrin should be considered in patients with clear loss-of-function GABRB3 variants.

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