Molecular and Biological Aspects of Apoptosis - Extrinsic pathway: role of death receptors
13 important questions on Molecular and Biological Aspects of Apoptosis - Extrinsic pathway: role of death receptors
What are the three types of death receptors?
- CD95/Fas receptor
- DR4 and DR5 receptors
- TNF receptor
Why is the CD95/Fas receptor essential for the removal of cells that threaten homeostasis?
- Autoreactive T cells with the potential to attack ''self'' are removed by apoptosis
- At the termination of an immune response when they are no longer needed
- Inflammatory cells in immune-privileged tissues (brain, eyes, testis)
- Inflammatory cells in a tumor
Other cells: virus infected cells
Multistep Fas activation
- Higher grades + faster learning
- Never study anything twice
- 100% sure, 100% understanding
For my 1st exam I got a C. Then, I started looking for ways to learn better and I came across Study Smart. Since then I have scored a A+, A, A- and another A. I highly recommend it to everyone who wants to hear it. I am so happy with it!!
I was struggling to finish all my first-year subjects for 3 years. Then I discovered Study Smart, which helped me to finish all of them within 3 months.
Because of StudySmart, things are going well in many ways. Before, I always had study stress and no time for anything. Now I feel calm and confident (because of the program). I used to score a B, now I usually score an A or A+.
Hey Chris, I really want to thank you very much for developing the platform, I usually got around C for my exams, now I scored an A+, an A and a A- !!
Since using Study Smart, my average has increased significantly. I even completed a statistics course with a A+ while I'm bad at statistics. I took on extra courses this year, because of Study Smart. Thanks so much!
Ever since I started studying with StudySmart I passed all my exams !!! No more re-sits!! At first, I was happy with a pass and now I only get good grades. Many thanks!
I aced all the courses I studied with Study Smart. For law, I first scored a D, and now an A! I’m 100% sure that I’ll pass all the courses I study with Study Smart.
I always thought I studied well. My grades were fine. I could never have imagined that applying these study skills would have such a huge and direct impact on my grades, my speed and the pleasure I have in learning.
For the first time, I finally feel totally confident about the way I learn. I have the perfect overview and make great progress in terms of speed and the grades I get. Thanks, Chris!
I immediately started to enjoy learning again, and my grades soared. All of a sudden, everything went better. I highly recommend Study Smart to all students..
Being able to create my materials online made the process of studying so much smoother and quicker. I no longer have to spend a huge amount of my time on creating my summaries.
At first, my notes were a mess. Now I use Study Smart to take my notes in a perfectly structured way. It helps me to save a lot of time and do other things I enjoy.
Students that study with Study Smart get better grades. The system applies all the learning methods in such a way that both well-performing students and students who struggle perform much better.
Hi Chris, I would like to thank you very much. Last year I scored C on a course, and this year I got an A+ thanks to your method! Thank you very much!
The largest effect is that my child is more enthusiastic about school! Every parent wants their children to be happy at school, Study Smart made it happen.
In high school, I failed several exams, and that has really changed now. I actually needed this tool very much back then. Since I started studying with StudySmart, I haven't had any D's. My average score is now an A and those are results I would have never had in the past
With my old method, I passed only 3 out of 8 courses. Since I started taking my notes digitally in Study Smart, I have passed all my courses on the first try. For me, StudySmart takes away the stress of wondering if I will pass or not.
Thanks to StudySmart, I passed all my exams, and with better grades than before! On top of that, I have mastered a very good study method now, which I am confident will help me earn my degree.
Three types of cells killed by the Fas-FasL system
- Virus infected cells: cytotoxic T cells recognize MHC complex with viral antigen, inducing apoptosis via FasL.
- End of immune response: T-lymphocytes express both FasL and Fas. APC activates the receptors through MHC/antigen with T cell receptor.
- Removal of inflammatory cells: immune-privileged cells express FasL to kill cytotoxic T cell via Fas receptor.
Ways of Fas-mediated immune escape by tumors
- FasL-expressing tumors can induce T cell apoptosis.
- Cancer cells can be resistant to Fas-mediated apoptosis
- Cancer progression is associated with increased FasL expression
DR4, DR5 and its modulation by decoy receptors
Apoptosis signaling by DR4 and DR5 (TRIAL-R1/R2)
- Death Inducing Signaling Complex (DISC), which consists of FADD, RIP, pro-caspase-8
- Induction of apoptosis via caspase-8 directly to caspase-3, or by caspase-8 recruiting BID
- Mitochondrial signaling via Bax/Bak, releasing cytochrome C to form apoptosome with caspase-9 inducing caspase-3
- Inhibition of apoptosis by XIAP, which can inhibit caspase-3 and caspase-9
Tumor necrosis factor (TNF) signaling pathway
- TNFa ligands binds to receptor to activate it
- TRADD binds and activates kinase
- Kinase can activate NF-kB (transcription factor)
- If activated, it travels to the nucleus and transcribes inflammation factors and anti-apoptosis proteins.
Mechanism of NF-kB action
- Stimulation. Of TNFR1 leads to the binding of TRADD, recruiting FADD and TRAF2
- TRAF2 associates with RIP1 for IKK activation, which in turn phosphorylates the IkBa protein resulting in ubiquitination and dissociation from NF-kB
- NF-kB translocates to the nucleus where it binds to response elements in the DNA.
What does prolonged activation of TNF lead to?
RIP1 is part of which complexes?
- Complex I: activation of kinases, followed by activation of NF-kB
- Complex II: involved in apoptosis
- Necrosome: interaction with RIP3 to induce necrosis
How does RIPK3 induce necroptosis?
Role of ubiquitin in the TNF pathway
- RIP1 is polyubiquitinated by cIAPs, leading to the recruitment of TAK1 and IKK complexes
- IkBa is ubiquitinated, leading to NF-kB activation
- Deubiquitinated-RIP1 dissociates from TNF receptor forming complex II
Try our study magic for free
a PDF, study it super fast
- No sign up, email or credit card needed!
- AI makes unlimited flashcards
- Get unlimited quizzes and tests
- Ask AI anything
- No sign up, email or credit card needed!
- Have and keep perfect overview
- Make flashcards, notes and mind maps
- Review, test and score!
The question on the page originate from the summary of the following study material:
- A unique study and practice tool
- Never study anything twice again
- Get the grades you hope for
- 100% sure, 100% understanding
