zoo 131 - cell-to-cell communication in development

Juxtracrine signaling

a type of cell signaling that occurs between two adjacent cells that are in direct contact via a junction across the cell membrane that connects the cytoplasm of the two cells

paracrine signaling

secretes signaling molecules to close neighbors

extracellular matrix

insoluble network consisting of macromolecules secreted by cells.

Fibronectin

large glycoprotein, promotes cell adhesion and cell anchorage.

Laminin and type IV collagen

major components of the basal lamina

epithelial-mesenchymal transition (EMT)

orderly series of events whereby epithelial cells are transformed into mesenchymal cells; important in embryo development specifically the development of neural crest

Differential adhesion hypothesis

a model that sought to explain patterns of cell sorting based on thermodynamic principles

Cadherins

major cell adhesion molecule; maintains intercellular connections, spatial segregation of cell types, and organization of animal form.

catenins

link cadherins to the actin cytoskeleton

induction

interaction at close range between two or more cells or tissues of different histories and properties

inducer

the tissue that produces a signal that changes the cellular behavior of the other tissue

responder

cell or tissue being induces. Must have a receptor protein for the inducing pacrine factos, and must be able to respond

competence

the ability to respond to a specific inductive signal

instructive interaction

a signal from the inducing cell is necessary for initiating new gene expression in the responding cell

permissive interaction

the responding tissue has already been specified and needs only an environment that allows the expression of these traits

regional specificity of induction, genetic specificity of induction

two factors affecting induction between epithelial and mesenchymal tissue

autocrine interaction

The same cells that secrete paracrine factors also respond to them.

endocrine interaction

Type of cell signaling in which hormones are secreted directly into the bloodstream; can signal over long distances.

fibroblast growth factor (FGF) family, the Hedgehog family, the Wnt family, the TGF-beta superfamily

morphogenes families

morphogen

paracrine factors that regulates gene expression. determines cell fate based in concentration

notch

transmembrane protein that interacts with other transmembrane protein and neighboring cells and can activate transcription based on nearby transmembrane protein.

selective affinity

positive and negative affinities within germ layers

E-cadherin

cadherin expressed on all early mammalian embryonic cells

P-cadherin

cadherin found predominantly in the placenta, where it helps the placenta stick to the uterus

N-cadherin

cadherin highly expressed on the cells developing central nervous system

R-cadherin

critical in retina formation

protocadherins

lacks the attachement to the actin skeleton through catenins.

formation of boundaries between different tissues

interaction of R-cadherin and Beta cadherin

polarization

first stage of migration; cells defines its front and its back

protrusion

second stage of migration; polymerization of actin microfilaments at the cell membrane creating long parallel bundles

adhesion of the cell to its etracellular matrix

third stage of migration

integrin proteins

key molecules in the third stage of migration; spans the cell membrane, connecting the extracellular matrix outside.

release of adhesion in the rear

fourth stage of migration.

paracrine factors

proteins made by a cell or a group of cells that alter the behavior or differentiation of adjacent cells.

BMP4

protein that is received by the lens cells and induces the production of the Sox2 transcription factors

Fgf8

signal that induces the appearance of the L-maf transcription factor

paracrine factors

function by binding to a receptor that initiates a series of enzymatic reactions within the cell

receptor tyrosine kinase (RTK)

kinase activity that can use ATP to phosphorylate specific tyrosine residue of particular protein.

acidic FGF

Fgf1 protein also known as____ appears to be important during regeneration

basic FGF

Fgf2 sometimes called as ___ important in blood vessel formation

keratinocyte growth factor

Fgf7 critical for skin development.

Fgf8

FGF important during limb development and lens induction

fibroblast growth factor receptor (FGFRs)

FGF works by activating a set of receptor tyrosine kinase called

alignment of cells

when fibronectin interact with appropriate molecules results in

paracrine factors

repress expression of genes

reciprocal induction

The inducer becomes the induced

regional specificity of induction

region of an inducer tissue can specify the in surrounding competent tissue (chicken example)

genetic specificity of induction

a tissue being induced can only respond if its genome permits.

Juxtracrine interaction

membrane proteins on one cell surface interact with the receptor proteins on an adjacent (or justaposed) cell surface.

paracrine interaction

when protein synthesized by one cell can diffuse over small distances to induce changes in neighboring cells.

autocrine interaction

a type of paracrine interaction where the inducer cells creating the paracrine factors also respond to the factors

morphogen

paracrine factors that regulates gene expression. determines the fate based in concentration

regulation of transcription factors and regulation of cytoskeleton remodeling

paracrine factors function by binding a receptor which cause two things:

JAK-STAT pathway

pathway extremely important in the differentiation of blood cells, the growth of the limbs, and the activation of the casein gene during milk production

wynt family

family of cysteine-rich glycoproteins

hedgehog family

family of paracrine factors often used by the embryo to induce particular cell types and to create boundaries. between tissues.

notch proteins

involved in the formation of numerous vertebrate organs—kidney, pancreas, and heart—and are extremely important receptors in the nervous system

(1) formation of neural crest cells (2) formation of mesoderm in chick embryos (3) formation of vertebrae precursor cells from the somites

examples of developmental processes in which this transition is active

FGFs

angiogenesis, mesoderm formation, axon extension, midbrain development, limb development.

hedgehog family

formation of boundaries between tissues, spermatogenesis, postanal bone growth, patterning or neural tube

wnt family

induction of dorsal somite cells for muscle formation, polarity of limbs, axon extension, urogenital system development

TGF beta superfamily

bone morphogenesis, kidney and neuron differentiation, mammalian sex determination, formation of extracellular matrix

specification and determination

two stages of commitment

specification

cell tissue differentiates autonomously when placed in a neutral environment

determination

cell or tissue differentiates according to its original fate even under different conditions

autonomous specification, conditional specification, synthetic specification

modes of cell type specification

autonomous specification

by differential acquisition of certain cytoplasmic molecules present in the egg

conditional specification

by interaction among cells

syncytical specification

by interaction between cytoplasmic region prior to cellularization of blastoderm