Develpomental Biology Exam 4

chapter 7

What is required to prevent tissues from falling apart?

cells need to stick to each other

What is supposed to be present for cell adhesions?

specific proteins

cadherins

transmembrane proteins

Which types of adhesions are cadherins involved in?

adherens junction

desmosome

What movement do cadherions follow?

start inside cell

cross cell membrane

then extracellular portion

What do cadherins bind to?

other cadherins

What must be present in order for cadherins to bind to ther cadherins

Ca2+

How many different types of cadherins in vertebrate species?

30+

Hemidesome

adhere a cell to the basement membrane

The types of cell-cell adhesion

adherent junction

desmosome

calcium-independent adhesion

adherins junction

cadherins extend outward

2 sets of proteins inside cell

actin bundles that make up actin filaments inside cell

variety of catenins attach cadherins to actin

desmosomes

cadherins extend outward

2 sets of proteins insides cell (plakoglobin and desmoplakin)

these proteins attach cadherins to intermediate filaments

calcium-independent adhesion

interactions between two different cells in the absence of Ca2+

What is happening with calcium-idenpenent adhesion?

requires different immunoglobulins to mediate cell-cell adhesionand does not rely on cadherins.

immunoglobulins

cell surface markers

ex N-CAM

What do the cell-cell adhesions not do?

they do not limit what passes between the cells

they are not tight junctions

tight junctions

seal off transport between cells

examples of tight junctions

occludin

claudins

cell-matrix adhesion

use interns to bind cell to the matrix

integrins

integrate with the cell membrane

what are the inside cell integrins attached to?

cytoskeleton

in cell-matrix adhesion, what attaches integrin to actin instead of catenin

vinculin and valin

what do integrins interact with outside of the cell

laminin

What has to happen so that the cell can move?

adhesions must change/ be eliminated and the cell must change shape

T or F: different tissue types have different adhesion molecules

true

What are cohesive properties?

how likely cellls are to stick to eachother. how much surface tension they can form

Which tissue type is most cohesive?

ectoderm

What tissue type is least cohesive?

endoderm

What things help cells change shape?

actin filaments

microtubules

intermediate filaments

How can a cell change shape using actin?

cleavage

apical constriction

migrating cell

Intermediate filaments

stable

rope-like

used for mechanical forces

What are microtubules important for

asymmetry

movement of organelles

nuerons example

make stuff in the cell body and need to move it to other end

“roads” made from microtubules

What are actin filaments made of?

globular actin subunits

Different examples of when actin is used in changing cell shape?

cleaving a cell uses a contractile ring made of actin

change of shape on one end

cell developing pseudopodia

Epithelial

sheet of cells connected to basebmetn membrane

What happpens in the transition from epithelial to mesenchymal?

lose adherins junctions and connection to basement memrance turn to mesenchyme.

mesenchyme

individual cells suspended in matrix

not attached to membrane

Types of cleavage

radial

spiral

unequal

Radial cleavage

urchin and dutorostomes

Spiral cleavage

annelids and molluses

unequal cleavage

nematode

What does the cleavage depend on?

Yolk setup

Which pole has less yolk?

animal

How does a cell become a blastula?

exrete fluid and expand

same volume, just larger blastocoel

every cell is polarized to get apical and basal side

Apical side

face inward toward the lumen/blastocoel

Basal side

outside the embryo

division of zygote in nematode

Par2 and Par3 in outer area

centrosomes get pulled asymmetrically

Astral microtubule

release surface tnsion on outside of cell

two cleavages in mice

radial

tangential

What do the polarized part of a tangential cleavage become

trophoblasts

What do the non-polarized parts become?

inner cell mass

What do trophoblsts give rise to?

placenta

What do inner cell mass give rise to?

embryo

Cdx2

labels cells that become trophectoderm

Oct4

expressed by cells becoming inner cell mass

E-cadherins

makes sure trophoblasts align properly on the outside

What happens without E-cadherins?

jumbled mess

cell does not know where to go

cannot polarize properly

Cell with tangential cleaveg produces?

a cell with Cdz2 and a cell with Oct4

Cell with radial cleavage produces?

Two Cdx2 cells

Cell with radial cleavage and cell sorting gives?

Oct4 on the inside

What do tight junctions form to do?

Prevent stuff on the outside getting to the blastocoel

can still pull in water and sodium

Protiens that create tight junctions

occludins and Claudius

What needs to happen so gastrulation can happen?

epithelial to mesenchymal transition

Shape of cells in vegetal pole of urchin

cuboidal

cilia on one side and basal lamina on another

What happens to cells in vegetal pole during gastrulation

they detach from adjacent cells and migrate inward into blastocoel as single individual cells

What happens to mesechymal cells

they migrate in and form a ring

Mesechyme movement

enter indivdually

form ring

extend ventrally

How do they move in individually?

They lose cadherins and catenins by the expression of Snail and Slug

What is a real life example of this expresion of Snail and Slug for detachment

cancer cells that start to become metatstatic

What attaches to the basal laminate inside the blastula?

philopodia

How do the mesechymes know where to move in?

The expression of FGF and VegF

What do mesenchymes express?

FGF receptor

What makes FGF?

ectoderm

Where is VegF

ventral ectoderm

What are the secondary mesocnhyme?

the other stuff moving in from the gut

primary mesenchyme

orignial mesodermal cells at the vegetal pole

secondary mesenchyme

cells originally going to be endoderm, but change and loose attachments and catenins.Go higher on the cell and form same pdilopodia

How is the gastrula forming

butt end of secondary mesonchyme is still attached to the endoderm and pulling the endoderm up

Cell shape change in endoderm

cells go from sqaure to triangle/wedge (pinched the bottom)

Change in cell shape leads to…

invagination which allows gut formation

Convergent extension

endoderm is stretchings and thinning out

Drosophila example

cells migrate to become mesoderm

Twist and Snail expressed where mesoderm will form

Snail

forces us to get rid of adhesions and adherins junction

Twist

controls catenins

In drosophila we get a doubling in length of abdominal region during gatrulation stage because of..

convergent extension

dorso ventro axis

up and down

Planar cell polarity

cells knowing where their axis are

knows which way to grow

What do we need to set up planar cell polarity

transmembrane protein

morphogenetic gradient

what goes under apical reconstruction to form the gut in the frog?

bottle cells

archanteron

gut space

Difference cells moving in

cells moving together as a sheet rather than seperate cells

What starts as a ring then is moved around to a skinny strip in the frog?

brachyary

radial intercalation

take thick layer of cells and squish it out flat

Wher else does convergent extension occur

formation of Xenopus notochord

inactive boundary

barrier for convergent extension

medio-lateral intercalation

convergent extension

non canonical Wnt pathway

1. Wnt binds to frizzled

2. Disheveled is activated

3. Disheveled activaties side pathway or

4. Disheveld activates RhoA directly

5. RhoA activates Rok2

6. Rok2 changes up cytoskeleton so we now which direction is which

7. Disheveld activates JNK

8. or activating different sets of genese though AP1

what are we using this wnt pathway for

to move mesoderm

Cells moving at primitive streak

epithelial to mesechymal transition