Developmental biologhy Flashcards
Intrinsic regulation =….
Regulators of self-renewal within a cell is localized asymmetrically
What are PAR proteins? Why are they so important during development?
PAR proteins are internal cellular signals for polarisation. They are important because the loss of PAR proteins effect the localization on the other side. There is a relationship between PAR proteins and asymmetry in order for 2 daughter cells to dissociate.
What does the mitotic spindle do during cell division?
It gives orientation to the cell division by mechanical forces
What are the spindles made of?
Of centromers that have filaments of microtubuli which attach and pull.
Improper spindle orienation is linked with….
Disease and tumor formation
The cortical force consists of…
The combination of the pulling force and dynein
Which proteins affect spindle force?
GPR-1/2 in associated with LIN-5 that activate the G-protein
Extrinsic polarization =,,,
The stem cell is in close contact with the stem cell niche which maintains the potential to self-renewal
Niches =…
Local tissue microenvironments that maintain and regulate stem cells
Stem cells are controlled by activation agents ….
Notch signalling from DTP niche as it results in cell differentiation
Function of ASPM (abnormal spindle-like, microcephaly associated)
It regulates spindle orientation by interacting with kinase and by creating a division between the pulling forces
What happens when there is less ASPM/CITK?
The cells quickly leave the cell cycle and have fewer microtubules, so the cell divide symmetrically
LIN-5 in c.elegans is an ortholog of…
ASPM in humans
ASPM recruits…
CITK to the microtubules to promote stabilization
Name 4 processes which favored multicellarity
- Differentiation to ensure proper function
- Damaged/old cells programming to die e.g. necrosis/apoptosis
- Growth in size which maintains functionality
- Increasing in cell number to boost organ and body size
Whats the difference between pluripotent and totipotent cells?
Pluripotent cells can give rise to all cell types of the body and totipotent cells are capable of giving rise to all cell types of the body and extra-embryonic tissue
Spemann organiser =
It directs groups of cells into tissues and organs of the embyro by induction
Whats the function of Chroding and Noggin?
They are released to prevent BMP-4 signaling which causes a different cell fate, so prevent differentiation.
What are morphogens?
Long-range molecules that act in a concentration-responsive matter to induce a cellular response
Inductive interaction =…
A group of cells which are identical but a signal to one cell causes a different cell fate. Limited in space and time.
Name 3 levels at which cell polarity can be controlled
- single cell
- small group of cells
- tissue level
How is single cell polarity controlled?
Cells can be polarized by intracellular signals e.g. one-cell embryo (intrinsic polarity)
How are a small group of cells controlled in polarity?
Cells can be polarized by short-range signals from the stem cell niche e.g. DTC as niche
How are tissue controlled in polarity?
Morphogens determine the organization of polarity e.g. WNT- and Hedgehog signalling
How do the majority of human cancers arise?
They arise from the epithelial tissue due to loss of cell polarity and tissue disorganization
Which complexes interact with PAR and how?
Crumbs complex maintains the structure and Scribble complex but then on the basal side. They interact with each other to maintain a distinguished structure.
What is the relation between cell junctions and polarity?
Polarity is relayed to the tight junctions and adherent junctions dynamics at the cell-cell surface, these are critical for the development and maintenance of the tissue (occluding + claudin)
Adherent junctions have…
mechanical support function but also allow signaling and transport
Cadherins connect to…
the internal port with catenin by an anchor
Tight junctions function in…
sealing the intracellular space and working as a barrier against migration, it establishes cell-cell interactions and binds to the cytoskeleton
What are the consequences of low core polarity expression?
It weakens the adherent junction complex which results in epithelial-to-mesenchymal transition and consequently malignancy
Planar cell polarity functions in…
coordination of orientation of cells and cellular structures along an axis in the plane of the epithelial surface
