Bio 1-L7-Cell to Cell communication

2 broad types of cell signalling in eukaryotes

1. contact dependent

2. secreted molecules

juxatcrine signalling- the types

• gap junctions between animal cells

• plasmodesmata between plants

• cell to cell recognition

gap junction juxtacrine signalling examples and features

have protein channels embedded in the membrane of adjacent

• cardiomycte gap junctions make heart beat- allows Ca2+ and Na+ to pass freely between

• allows electrical signals to pass through

• allows depolarisation

plasmodesmata- juxtacrine features and what is it in

• used in plants

• connects plant cells- gaps in membrane cell wall- NO PROTEIN CHANNEL

• have ER extension tubules- called desmotubulues

• transports metabolites, proteins, RNA- share gene expression

juxtacrine- signalling pathway type example

NOTCH signalling- glial support, neurons, learning and memory

secreted molecules- what do they usually do or change?

• usually used for altered metabolism

• altered cytoskelton

• altered gene expression and cell division

types of secreting molecules?

• endocrine signalling- through blood- insulin

• paracrine- targets local cells

• autocrine- within cell- targets the same cell

• paracrine signalling synaptic- neurons etc

immune response- example and types of signalling involved

• juxtacrine first- MHC II and T cell receptors- activation is made through contact

• autocrine- once activated- I cells secrete IL-2 cytokines and binds to itself and makes effector T cells-

what do WNT proteins do and signalling pathway- what type of signalling?

• act as morphogens by secretion of gradients- paracrine

1. Want binds to frizzled receptor and recruits DISHEVELLED

2. Beta catenin is stabilised in the cytoplasm- DISSOCIATES destruction complex

3. this is transported to the nucleus

4. binds to the transcription factor Tcf AND TURNS ON GENE EXPRESSION

neuromuscular junction- what does it use?

acetylcholine Ach- paracrine signalling

• Ach binds to receptors- opens sodium channels

• causes depolarising- opens voltage gated

• depolarisation leads to action potential- muscle contraction

endocrine signalling- examples

• long distance signalling such as insulin

• beta cells in the pancreas recognise high glucose levels

• release insulin into bloodstream to hit target cells and uptake glucose to make ATP

NOTCH signalling steps

1. delta binds to notch receptor

2. 1st cleavage S2 mediated by ADAM10 enzyme

3. 2nd cleave-S3 mediated by gamma secretase

4. releases Notch intracellular domain- translocated to the nucleus

5. in nucleus binds to CSL Tf and changes cell fate and behaviour