This post will examine several things:
1. What are stem cells? and what is ACD?
2. What are the important features of ACD?
3. Examples from model organisms.
4. Diseases.
There are many different types of stem cells in our bodies. Stem cells go on to produce specific cell populations in development. For example, the ectoderm gives rise to neural stem cells which proliferate into neurons, skin, hair, and the mammory glands.
Stem cells have several properties. First, they must be able to self-renew. Second, they must possess a certain potency. That is, they need to have the ability to divide to produce differentiated cells. Totipotent stem cells can go on to produce every type of cell. Pluripotent and multipotent stem cells are more limited in the cell populations that they can proliferate into, but they can still give rise to a large diversity of different cell populations.
Asymmetric cell division is the division of one cell that gives rise to two cells with different fates. Normal cell division gives rise to two cells of equivalent fates. Stem cells divide asymmetrically, giving rise to two distinct daughter cells, a copy of the original stem cell as well as another daughter with a non stem cell fate.
Centrosomes and the mitotic spindle play a key role in whether cells differentiate from the stem cells or not.
So how do stem cells divide? Well, several factors come into play. First, polarity cues provide the signal to divide or not. There are both intrinsic and extrinsically-activated cues. We also have asymmetrically localized determinants - cell polarity determinants and fate determinants. Some common fate determinants are proteins (Numb being a key protein in determining neuronal fate), RNA, DNA, asymmetric phosphorylation, and organelles. Mitotic spindle apparatus orientation also plays a big role.
Steps in ACD:
- Interphase: Setting up axis of cell/ Polarity cues
- Pro-metaphase: fate determinants segregated
- Metaphase: Mitotic spindle orients in cell
- Telophase: light coordination segregates components to different cells.
We can study stem cells in most of the common model organisms. For example, big strides are being made in stem cell research in C. Elegans, yeast, C. Cerevisae, Drosophila, and mice (neural stem cells).
Neural stem cells function to produce neurons. You can find them in both the PNS and the CNS. They can include both pluripotent stem cells and multipotent progenitor cells. And they can be found both during development and during adult homeostasis, interestingly enough.
1. What are stem cells? and what is ACD?
2. What are the important features of ACD?
3. Examples from model organisms.
4. Diseases.
Stem cells have several properties. First, they must be able to self-renew. Second, they must possess a certain potency. That is, they need to have the ability to divide to produce differentiated cells. Totipotent stem cells can go on to produce every type of cell. Pluripotent and multipotent stem cells are more limited in the cell populations that they can proliferate into, but they can still give rise to a large diversity of different cell populations.
Asymmetric cell division is the division of one cell that gives rise to two cells with different fates. Normal cell division gives rise to two cells of equivalent fates. Stem cells divide asymmetrically, giving rise to two distinct daughter cells, a copy of the original stem cell as well as another daughter with a non stem cell fate.
Centrosomes and the mitotic spindle play a key role in whether cells differentiate from the stem cells or not.
So how do stem cells divide? Well, several factors come into play. First, polarity cues provide the signal to divide or not. There are both intrinsic and extrinsically-activated cues. We also have asymmetrically localized determinants - cell polarity determinants and fate determinants. Some common fate determinants are proteins (Numb being a key protein in determining neuronal fate), RNA, DNA, asymmetric phosphorylation, and organelles. Mitotic spindle apparatus orientation also plays a big role.
Steps in ACD:
- Interphase: Setting up axis of cell/ Polarity cues
- Pro-metaphase: fate determinants segregated
- Metaphase: Mitotic spindle orients in cell
- Telophase: light coordination segregates components to different cells.
We can study stem cells in most of the common model organisms. For example, big strides are being made in stem cell research in C. Elegans, yeast, C. Cerevisae, Drosophila, and mice (neural stem cells).
Neural stem cells function to produce neurons. You can find them in both the PNS and the CNS. They can include both pluripotent stem cells and multipotent progenitor cells. And they can be found both during development and during adult homeostasis, interestingly enough.
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