#lateral inhibition

Morphogen Induction-l

Which of the following is an example of lateral inhibition?

Lateral inhibition describes feedback where cell adopting primary fate inhibits neighbors through contact-mediated signal preventing same fate adoption. In Drosophila neuroectoderm, prospective neuroblast expresses high Delta activating Notch in surrounding cells. Notch induces Enhancer of split complex repressing proneural genes achaete-scute, forcing neighbors toward epidermal fate and limiting neuroblast density. This generates spaced array of neuroblasts separated by epidermis. BMP gradient in limb bud specifies digit identity via thresholds, not inhibitory cell-cell choice. Notch-Delta neuroblast singling out is textbook lateral inhibition model also seen in inner ear patterning.

Ref: Artavanis-Tsakonas et al., Science 1999, Notch-Delta Lateral Inhibition in Neurogenesis.

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Induction Morphogen -ll

Which of the following defines 'lateral inhibition'?

Lateral inhibition generates fine-grained mosaic patterns via feedback where differentiating cell actively inhibits adjacent cells from adopting identical fate. Classic mechanism involves Notch-Delta: prospective neuron expresses Delta, activating Notch in neighbors, which upregulates Hes repressors that suppress neural differentiation genes like achaete-scute, forcing neighbors into epidermal fate. This amplifies small initial stochastic differences, producing spaced pattern of bristles, hair cells and neural precursors. It contrasts with lateral induction where signal promotes same fate. Mathematical modeling shows lateral inhibition creates alternating checkerboard patterns essential for sensory organ spacing, angiogenic tip-stalk selection and intestinal secretory patterning.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 4: Lateral Inhibition and Notch-Delta Patterning.

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Specification Determination-ll

Which of the following is an example of lateral inhibition in development?

Lateral inhibition generates fine-grained mosaic of alternate cell fates among initially equivalent cells using Delta-Notch juxtacrine feedback. A cell stochastically expressing slightly more Delta ligand activates Notch receptor in neighbors, triggering transcriptional repression of proneural genes and Delta itself, preventing neighbors from adopting same fate while reinforcing signal in the initial cell. This amplification creates checkerboard patterns exemplified by selection of single neuroblast from proneural cluster, spacing of bristles, and hair cell versus support cell choice in inner ear. Although question lists Bicoid as example, classic paradigm is Notch-Delta mediated inhibition.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 5: Lateral Inhibition and Notch-Delta Patterning.

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C-Elegans Development-l

Which protein is the C. elegans homolog of Delta, involved in lateral inhibition?

Delta-Notch lateral signaling components are conserved across nematodes, flies, vertebrates. LAG-2 encodes transmembrane DSL ligand homologous to Drosophila Delta with multiple EGF repeats and DSL domain required for Notch binding, expressed in anchor cell and P2 signaling cells. Its extracellular domain binds LIN-12 and GLP-1 Notch receptors triggering metalloprotease S2 and presenilin gamma-secretase S3 cleavage, releasing NICD transcription complex with LAG-1 CSL and SEL-8 Mastermind activating hes homologs. LAG-2 patterning ensures single anchor cell and ABp induction, making canonical Delta equivalent mediating juxtacrine communication.

Ref: Tax et al., Nature 1994: LAG-2 is Delta homolog, ligand for LIN-12 and GLP-1 Notch receptors.

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C-Elegans Development-l

Which protein is involved in lateral inhibition during anchor cell specification?

Anchor cell versus ventral uterine precursor decision employs canonical lateral inhibition via Notch family receptors. Two equipotent cells Z1.ppp and Z4.aaa coexpress receptor LIN-12 Notch and ligand LAG-2 Delta-like. Initial stochastic difference amplifies via transcriptional feedback loop: cell with slightly higher LIN-12 signaling downregulates LAG-2 transcription via LAG-1 CSL repression, adopting ventral uterine fate, while neighbor with high LAG-2 low LIN-12 becomes anchor cell secreting LIN-3 and lag-2 for pi specification. LIN-12 intracellular domain released by presenilin SEL-12 cleavage translocates to nucleus ensuring single anchor cell.

Ref: Greenwald, WormBook Notch signaling: LIN-12 mediates lateral inhibition in anchor cell versus uterine precursor decision.

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Elegans -ll

Which protein is involved in vulval precursor cell lateral inhibition?

Vulval development provides model for lateral inhibition via Notch. Anchor cell secretes LIN-3 EGF inducing P5.p-P7.p to become vulval precursor cells. Among these, P6.p receiving highest LIN-3 dose adopts primary fate and expresses DSL ligands LAG-2, APX-1, DSL-1. These activate LIN-12 Notch receptor in neighboring P5.p and P7.p, triggering transcription of secondary fate genes lip-1, lst genes and repressing primary fate gene lin-39 hyperactivation. LIN-12 signaling thus ensures only one central cell becomes primary, flanking cells become secondary, preventing excessive primary lineage formation, central mechanism of lateral signaling patterning.

Ref: Sternberg, WormBook 2005; Gilbert Chapter 15: LIN-12 Notch lateral inhibition in vulval precursor cells.

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Cell Signaling Dev Bio & Other Pathways