Cell-Cell Communication and Morphogenesis

Flashcards covering key vocabulary and concepts related to cell-cell communication, morphogenesis, and major signaling pathways in developmental biology, based on the provided lecture notes.

Morphogenesis

The construction of organized form; the process where cells are ordered to create different shapes and make different connections during development.

Cadherin

A major calcium-dependent cell adhesion molecule anchored inside the cell by a complex of proteins called catenin.

Extracellular Matrix (ECM)

An insoluble network made up of macromolecules secreted by cells, forming the environment surrounding cells.

Integrin

Receptors for extracellular matrix (ECM) molecules that mediate cell-matrix and cell-cell adhesion.

Epithelial-Mesenchymal Transition (EMT)

A series of events where epithelial cells are transformed into mesenchymal cells, an important developmental phenomenon.

Induction

The ability of one cell or tissue to direct the development of neighboring cells or tissues.

Morphogen

A diffusible biochemical molecule that can determine the fate of a cell based on its concentration.

Gradient

Refers to a morphogen gradient, where the concentration of a diffusible signaling molecule varies with distance from its source, influencing cell fates.

Threshold

Specific concentrations of a morphogen that trigger different gene expressions and thus different cell fates, creating boundaries between cell types.

Juxtacrine Signaling

A type of cell-cell communication that occurs between two neighboring cells in direct physical contact, where proteins from the inducing cell interact with receptor proteins of adjacent responding cells.

Paracrine Signaling

A type of cell communication where cells secrete signaling proteins (ligands) into the extracellular matrix to affect neighboring cells over a short distance.

FGF (Fibroblast Growth Factor)

A major family of paracrine factors with nearly two dozen members, involved in various developmental processes like limb growth and lens formation.

Hedgehog

A family of paracrine factors identified in a genetic screen for body patterning, crucial in many developmental processes.

Sonic Hedgehog (Shh)

A vertebrate homolog of the Hedgehog protein, extremely important in developmental processes such as limb patterning, craniofacial morphogenesis, and neural differentiation.

Wnt

A family of paracrine factors (named from 'wingless' and 'integrated') critical for establishing polarity, promoting stem cell proliferation, and regulating cell fates in development.

TGF-β (Transforming Growth Factor-beta) superfamily

A major family of paracrine factors that includes the TGF-β family, activin family, bone morphogenetic proteins (BMPs), and Nodal proteins.

Notch

A receptor protein involved in juxtacrine signaling, which binds to Delta ligands to pattern cell fates through lateral inhibition.

Delta

A ligand protein that binds to the Notch receptor in an adjacent cell, initiating Notch signaling and lateral inhibition.

Heparan Sulfate Proteoglycan (HSPG)

Proteoglycans in the extracellular matrix that can modulate the stability, reception, diffusion rates, and concentration gradients of paracrine factors like FGFs, BMPs, and Wnts.

Cytoneme

Filopodia-like extensions involved in transferring morphogens between signaling and responding cells.

Lateral Inhibition

A Notch-Delta mediated mechanism of restricting adjacent cell fates, where an initial difference is reinforced by feedback, leading to one cell adopting a specific fate while inhibiting its neighbors from doing the same.

Differential Cell Affinity

The principle by which different cell types sort out into their own distinct regions during reaggregation, as seen in amphibian neurulae cells.

Differential Adhesion Hypothesis

A thermodynamics model explaining cell sorting and tissue formation based on differences in cell surface tensions mediated by adhesion molecules like cadherins.

Basal Lamina

A layer of extracellular matrix secreted by epithelial cells, upon which the epithelium sits.

Competence

The ability of a cell or tissue to respond to a specific inductive signal.

Reciprocal Induction

An inductive interaction where the two interacting tissues are both inducers and are competent to respond to each other's signals.

Instructive Interaction

A type of inductive interaction where a signal from the inducing cell is necessary for initiating new gene expression in the responding cell.

Permissive Interaction

A type of inductive interaction where the responding tissue has already been specified and only requires an environment that allows the expression of its traits, rather than a new signal.

Signal Transduction Cascades

The intracellular process initiated by a ligand binding to a cell membrane receptor, leading to a series of protein phosphorylations that ultimately activate or repress specific gene activity.