Lecture 1 (Giepmans):
There are two different types of diseases. Either caused by the immune system or
caused by genetic malfunction.
There are 5 important types of cell junctions;
- Tight junctions
Functions as a barrier, separating outside (exterior) and inside (interior), but also
facilitate cell signalling. The junction is apical – basolateral. These junctions can
be discovered by adding a dye that can be detected with electron microscopy.
Fluorescent labelling is also possible, as well as electrical current.
Tight junction molecules are JAMs, Claudins, and Occludin.
Zone Occludens.
- Adherens junctions/Adhesion sites
Cadherins are the molecules used in an adhesion site. They are dependent on
Ca2+, which activated the cadherin dimers. They bind to each other (from cell to
cell), to actin filaments, (sometimes) microtubules and the cytoskeleton of the
cells (anchoring the cytoskeleton). This forms the adhesion. They function as the
junctions keeping cells together and giving strength/structure to cells.
Zona Adherens.
- Desmosomes
They give strength to tissue and utilize the intermediate filaments of the cell
(anchoring to the cytoskeleton of the cell). Usually, a lot of desmosomes are
clumped together, making a really dense connection between cells. They consist
of Desmocollin and Desmoglein and have an inner and outer plaque area. They
are mostly found in tissues that are under high mechanical stress such as the
skin and the heart. It prevents the cells in these tissues from being pulled apart.
Macula Adherens.
- Gap junctions
A gap junction plaque consists of thousands of channels called connexons, that
consist of connexins. They can facilitate the diffusion of small molecules
between cells through these channels, also aiding in the signalling between
cells. They are ultimately important for Electrical synchronization, Energy
metabolism, Antigen presentation, Wound healing and Growth control. The GJ
can be closed and opened by the cell.
- Focal adhesions
,Most of these junctions use very similar proteins such as ZO-1
Lecture 2 (Giepmans):
Cell-Cell contact inhibition is the phenomena that when a cell is tightly bound in the
network of cells, its cell division is inhibited. Certain tumours exist because contact
inhibition is not present.
Signal regulation can work through 3 different ways related to cell-cell junctions. The
junctions acting as a magnetic bar, crosstalk between cell through signalling factors
and cleavage. Translocation and cascades are an example of cross talk. Cascades can,
for instance, be activated by a G-protein coupled receptor or a receptor tyrosine kinase
(RTK).
, Cell-cell junctions act as magnets for transcription (co) factors. Meaning that if there is
a cell-cell junction, it will recruit transcription factors to the membranes of the cell,
keeping them away from the nucleus. This will prevent the transcription factors from
turning certain genes on. Loss of cell-cell contact will result in the transcription factors
moving to the nucleus, turning certain genes on.
Proteins such as ZO-1 (promoting cell-cell junctions) and ZONAB (inhibiting cell-cell
junctions) can control the proliferation rate of a cell. Since these proteins are also
involved in the junctions between cells, it can also be said that the binding of a cell to
another cell regulates if a cell proliferates. If less ZONAB is present, it will inhibit
proliferation. If more ZO-1 is present, it will also inhibit proliferation. They are attracted
by the magnetic bar concept of the junctions.
Signalling between cell can also happen through a process called proteolysis. This is
where the binding of ligand to receptor causes the cleavage of, for instance, a part of
the receptor within the cell. This ‘rogue’ piece of protein can then act out certain
functions is the cell and act out the signal.
Lecture 3 epithelial tissue (Mauthe):
In the body there are 4 different types of cells/tissues. These are the nerve cells, muscle
cells, connective tissue cells and the epithelial cells. In this lecture we focus on the
epithelial cells. The epithelial cells are found in the lining of the gastro-intestinal tract
organs, in other hollow organs and on the skin surface.
The function of epithelial tissue is to separate an organism's internal from its external
environment, acting as a protecting layer (skin). It also has functions of absorption
(intestines), filtration (kidneys), secretion (endocrine glands), and sensation (eyes).
There are various subtypes of epithelial tissue;
- Squamous
o Simple or Stratified
- Cuboidal
o Simple or Stratified
- Columnar
o Simple or Stratified
- Trachea
o Special
- Bladder
o Needs to expand so this is special
Some of these subtypes are single layered epithelia (simple) and others are multi-
layered epithelia/glands (stratified).
There are two different types of diseases. Either caused by the immune system or
caused by genetic malfunction.
There are 5 important types of cell junctions;
- Tight junctions
Functions as a barrier, separating outside (exterior) and inside (interior), but also
facilitate cell signalling. The junction is apical – basolateral. These junctions can
be discovered by adding a dye that can be detected with electron microscopy.
Fluorescent labelling is also possible, as well as electrical current.
Tight junction molecules are JAMs, Claudins, and Occludin.
Zone Occludens.
- Adherens junctions/Adhesion sites
Cadherins are the molecules used in an adhesion site. They are dependent on
Ca2+, which activated the cadherin dimers. They bind to each other (from cell to
cell), to actin filaments, (sometimes) microtubules and the cytoskeleton of the
cells (anchoring the cytoskeleton). This forms the adhesion. They function as the
junctions keeping cells together and giving strength/structure to cells.
Zona Adherens.
- Desmosomes
They give strength to tissue and utilize the intermediate filaments of the cell
(anchoring to the cytoskeleton of the cell). Usually, a lot of desmosomes are
clumped together, making a really dense connection between cells. They consist
of Desmocollin and Desmoglein and have an inner and outer plaque area. They
are mostly found in tissues that are under high mechanical stress such as the
skin and the heart. It prevents the cells in these tissues from being pulled apart.
Macula Adherens.
- Gap junctions
A gap junction plaque consists of thousands of channels called connexons, that
consist of connexins. They can facilitate the diffusion of small molecules
between cells through these channels, also aiding in the signalling between
cells. They are ultimately important for Electrical synchronization, Energy
metabolism, Antigen presentation, Wound healing and Growth control. The GJ
can be closed and opened by the cell.
- Focal adhesions
,Most of these junctions use very similar proteins such as ZO-1
Lecture 2 (Giepmans):
Cell-Cell contact inhibition is the phenomena that when a cell is tightly bound in the
network of cells, its cell division is inhibited. Certain tumours exist because contact
inhibition is not present.
Signal regulation can work through 3 different ways related to cell-cell junctions. The
junctions acting as a magnetic bar, crosstalk between cell through signalling factors
and cleavage. Translocation and cascades are an example of cross talk. Cascades can,
for instance, be activated by a G-protein coupled receptor or a receptor tyrosine kinase
(RTK).
, Cell-cell junctions act as magnets for transcription (co) factors. Meaning that if there is
a cell-cell junction, it will recruit transcription factors to the membranes of the cell,
keeping them away from the nucleus. This will prevent the transcription factors from
turning certain genes on. Loss of cell-cell contact will result in the transcription factors
moving to the nucleus, turning certain genes on.
Proteins such as ZO-1 (promoting cell-cell junctions) and ZONAB (inhibiting cell-cell
junctions) can control the proliferation rate of a cell. Since these proteins are also
involved in the junctions between cells, it can also be said that the binding of a cell to
another cell regulates if a cell proliferates. If less ZONAB is present, it will inhibit
proliferation. If more ZO-1 is present, it will also inhibit proliferation. They are attracted
by the magnetic bar concept of the junctions.
Signalling between cell can also happen through a process called proteolysis. This is
where the binding of ligand to receptor causes the cleavage of, for instance, a part of
the receptor within the cell. This ‘rogue’ piece of protein can then act out certain
functions is the cell and act out the signal.
Lecture 3 epithelial tissue (Mauthe):
In the body there are 4 different types of cells/tissues. These are the nerve cells, muscle
cells, connective tissue cells and the epithelial cells. In this lecture we focus on the
epithelial cells. The epithelial cells are found in the lining of the gastro-intestinal tract
organs, in other hollow organs and on the skin surface.
The function of epithelial tissue is to separate an organism's internal from its external
environment, acting as a protecting layer (skin). It also has functions of absorption
(intestines), filtration (kidneys), secretion (endocrine glands), and sensation (eyes).
There are various subtypes of epithelial tissue;
- Squamous
o Simple or Stratified
- Cuboidal
o Simple or Stratified
- Columnar
o Simple or Stratified
- Trachea
o Special
- Bladder
o Needs to expand so this is special
Some of these subtypes are single layered epithelia (simple) and others are multi-
layered epithelia/glands (stratified).
