Molecular and Cell Biology - Cell Signaling pt.1

What does cell signaling inolve?

• Cell signaling involves a number of different signals activating multiple combinations of molecules

  • The result is a diverse set of cellular responses

What are some potential inputs of cell signaling?

• Proteins

• Nutrients

• Ions

• Gases

• Photons

• Direct contact

What are some potential responses of cell signaling?

• Gene expression

• Protein function

• metabolism

• cell shape or movement

• differentiation

• proliferation

List the step in the signal transduction pathway

List the different signaling networks cell use to communicate

This allows for different points of regulation - essential in drug development

• Negative feedback

• Positive feedback

• Feedforward relay

• Stimulatory crosstalk

• Inhibitory crosstalk

Describe the two ways that cells can signal via a cell-cell model

1. Direct interaction with neighboring cells

2. Secreting signaling molecules

Describe the process of direct cell-cell (cell matrix) interactions. What Is this process important for?

• Integrins and Cadherins are signaling molecules

• Cells express surface receptors that interact with neighboring cells that have signaling molcules on their surface

• Critical for regulating the behavior of cells in animal tissues

  • important for embryonic development

  • Important for the maintenance of adult tissues

What are the three different categories we have cell signaling through secreted molecules?

1. Endocrine

2. Paracrine

3. Autocrine

List the major characteristics of endocrine signaling. What is one example as seen in the human body?

• Signaling molecules are called hormones

• Secreted by endocrine cells

• Travel through the circulation system

• Act on target cells at distant sites in the body

Ex:

• Estrogen

  • produced by the ovaries and stimulates the development and maintenance of female reproductive system and sex characteristics

Describe the characteristics of paracrine signaling. Give one example

• Signal molecules act locally to effect behavior of neighboring cells

  • molecule released by one cell acts on neighboring target cells

Ex: neurotransmitters

Describe the major characteristic of autocrine signaling. Give an example.

• Cell respond to signaling molecules that they themselves produce

Ex: Immune response

• T-Lymphocytes respond to antigenic stimulation by synthesizing growth factor

  • drives it own proliferation

  • increases the number of responsive T-lymphocytes

  • amplified the immune response

  • Note: abnormal autocrine signaling leads to cancer

Describe the characteristics of steroid hormones and the nuclear receptor family

• In most cases receptors are expressed on the cell surface

  • Some receptors are intracellular proteins located in the cytosol or nucleus

• Signaling molecules are small hydrophobic signaling molecules

• Signaling molecules are able to diffuse across the plasma membrane