lesson 2: cell signaling

Process by which cells communicate with other cells within their body or with the external environment

Cell signaling

How are cells sent signals?

• Signal perception/ reception

• Signal transduction

• Cellular response

If signal molecules are ____ and ____, ligand will bind to the receptor inside the cell

Small and hydrophobic

If signal molecules are ____ and ____, ligand will bind to the receptor in the surface outside the cell

Large and Hydrophilic

Produce by the same cells that recieve the signals. Within the cells, cells can send signal to itself. This usually involves secondary messengers

Intracellular signaling

A signal that travel throughout the body and involved neurotransmitter and hormones

Intercellular signaling

What are the 3 basic things in intercellular signaling?

Chemical messenger, travel and receptor

What are the chemical messengers: Ligands

Neurotransmitter, hormones, growth factor, and cytokines

What are the chemical messengers: Travel

Paracrine, endocrine, autocrine and juxtacrine

Cell releases signal which affects nearby cells. Signaling mol and target cells are within one tissue

Paracrine signaling

Target cells and signaling molecule are far from each other. Chemical messengers usually travels in bloodstream (usually: hormones)

Endocrine signaling

Cell releases messenger that affects itself or same type of cells

Autocrine signaling

Cells communicate by physical/direct contant to the ligand

Juxtacrine signaling

Give all 4 receptors

• Ligand gated ion channels (membrane potential and cell excitability)

• G protein coupled receptor (uses CAMP and IP3 as secondary messenger)

• Catalytic receptor (growth differentiation and metabolism)

• Nuclear receptor (gene expression and transcription)

Give all 4 target proteins

• Travel proteins

• Metabollic enzymes

• Gene regulation

• Cytoskeletal protein

• Cell cycle protein

Two functions of Intracellular signaling

Amplification and Integration

In genetics, it means making multiple copies of genes. Signal from Ligand is amplified towards the target cell

Amplification

Intracellular allows message or signals from ligand to converge and diverge

Integration

Different ligands produces one response

Converge

Ligand can activate 2 different secondary system having 2 or more response. In other words, one ligand can produce 2 different response.

Diverge

Process by which epithelial cells lost their epithelial properties just like cell to cell adhesion

Epithelial-mesenchymal transition

Epithelial cells are attached to?

Basement membrane/ basal lamina

It help epithelial cells to stay attached to basement membrane

Hemidesmosomes

This ligand trigger epithelial cells to lose their epithelial properties

Paracrine factors

What are the properties lost by Epithelial cells?

• E-Cadherin (cell to cell adhesion)

• Cytoskeletal re organization

• Complete detachment of epithelial cells to basement membrane

When apical and basal polarity of epithelial are lost, their shape becomes?

Spindel in shape

What are the mesenchymal genes?

• Snail (n-cadherin)

• ZEB

• Twist

What will be triggered when signals from paracrine factors decreases?

Mesenchymal to epithelial transition

Diffusable molecules (ligands) that work in a range of 15 cell diameter

Paracrine factors

Give 4 types of paracrine factors

• Growth factors

• Cytokines

• Morphogens

• Neurotransmitter

These are signaling molecules which regulate cell fate and tissue patterning during embryonic development

Morphogens

They secretes morphogens and gradient forms

Source cells

Activates one set of genes

High concentration

Activate different genes

Intermediate concentration

Active another set of genes or remains inactive

Low concentration

Family of cell signaling proteins produced by macrophages.

Fibroblast growth factors

What are the 3 subgroups of 23 growth factor family (fibroblast growth factor)

• Paracrine FGFs

• Endocrine FGFs

• Intacrine FGFs

A signaling pathways that transmit information to embryonic cells required for proper cell differentiation

Hedgehog Family

What are the 3 types of Hedgehog?

• Sonic Hedgehog

• Indian Hedgehog

• Desert Hedgehog

Encode a large family of secreted protein growth factors that have been identified in animals from hydra to humans

Wingless related integration site family

Multifunctional cytokine belonging to the transforming growth factor superfamily that includes 3 mammalian isoforms

TGF Beta or Transforming growth Factor

2 types of TGF

TGF alpha and TGF beta

A TGF factor mostly in epithelial tissue works

TGF alpha

A process that cause the organism to develop its shape, epithelial mesenchymal interaction (important during embryonic development) and etc.

Morphogenesis

A specialized cells for producing cartilage

Chrondocyte