How mitochondria may protect us from disease | Lena Pernas | TEDxPadova

Summary

This engaging presentation redefines mitochondria, not just as cellular powerhouses, but as ancient microbes with an active role in defending our cells. The speaker explains how mitochondria evolved from bacteria and, through a fascinating case study of the Toxoplasma gondii parasite, shows how mitochondria fight off invaders by competing for vital nutrients. The talk raises provocative questions about the microbial nature of mitochondria and explores how this new perspective could lead to novel antimicrobial strategies, while also drawing a philosophical parallel to the Greek Ship of Theseus to discuss identity and evolution.

Takeaways

• 😀 Mitochondria are not just powerhouses of our cells; they are also essential microbial entities with a unique evolutionary history.
• 😀 Mitochondria evolved from bacteria 1.5 billion years ago, and they retain bacterial traits, including their own DNA.
• 😀 All mitochondrial DNA is inherited from the mother, not the father.
• 😀 Mitochondria are crucial for producing ATP, the chemical energy necessary for life, and they consume 90% of the oxygen we breathe.
• 😀 Mitochondria are linked to various diseases, including neurodegenerative, cardiac, and age-related illnesses, when they are unhealthy.
• 😀 Mitochondria help produce important hormones such as testosterone, estrogen, and cortisol, which are vital for development and stress responses.
• 😀 During infections, mitochondria may play a defensive role against invading microbes, particularly in terms of nutrient competition.
• 😀 The human parasite Toxoplasma gondii is used to study how mitochondria react to microbial invaders. Mitochondria can prevent parasite growth by limiting access to fats.
• 😀 Enhancing mitochondria's ability to uptake fats can slow down parasite growth, while blocking this process allows the parasite to grow faster.
• 😀 Mitochondria may not simply be targets during infections but active defenders that protect cells from microbial threats.
• 😀 The question of whether mitochondria should still be considered microbes after evolving over 1.5 billion years raises philosophical and scientific debates, akin to the Paradox of Theseus.

Q & A

What is the main argument presented in the script regarding mitochondria?

The main argument is that mitochondria, traditionally seen as powerhouses of the cell, should be thought of as microbes due to their bacterial origins. This shift in perspective could help discover new ways to combat infectious diseases.

Why are mitochondria considered microbes?

Mitochondria are considered microbes because they share a common ancestry with bacteria. About 1.5 billion years ago, a bacterium entered a larger cell and eventually evolved into the mitochondria that we have today. They still retain some bacterial traits, such as their DNA and susceptibility to antibiotics.

What is the significance of the mitochondrial DNA being inherited only from the mother?

The fact that mitochondrial DNA is inherited only from the mother means that it has a unique lineage, distinct from the nuclear DNA that we inherit from both parents. This fact also links mitochondrial traits directly to maternal ancestry.

What role do mitochondria play in the body beyond producing energy?

Besides producing ATP, mitochondria help regulate important hormones such as testosterone, estrogen, and cortisol, which are essential for development, stress responses, and various physiological processes.

How are mitochondria related to the energy demands of our bodies?

Mitochondria are responsible for generating ATP, the chemical energy required for cellular functions. They use about 90% of the oxygen we breathe and the nutrients we consume to produce ATP, making them critical to powering all bodily processes.

What does the script suggest about how mitochondria might defend against microbial invaders?

The script suggests that mitochondria might not only be passive targets for invading microbes but could also actively defend cells by limiting access to nutrients like fats, thereby inhibiting the growth of invading parasites like *Toxoplasma gondii*.

What is the significance of *Toxoplasma gondii* in the context of this research?

*Toxoplasma gondii* is used in the research as a model organism to study how mitochondria respond to microbial threats. This parasite infects about one-third of the human population and serves as an example of how mitochondria might alter their behavior during infection.

What experiment was conducted to observe the interaction between mitochondria and *Toxoplasma*?

The experiment involved observing how *Toxoplasma* parasites interact with mitochondria within a cell. The results showed that mitochondria surround and seem to destroy the parasite, and they also alter their metabolism, especially in how they take up fats, to limit the parasite's growth.

How do mitochondria alter their behavior during an infection?

During infection, mitochondria alter their metabolism, particularly in their uptake of fats. This action deprives the invading parasite of necessary nutrients, effectively slowing its growth or inhibiting it altogether.

What broader implications does the research have for future treatments of infections?

The research suggests that by understanding how mitochondria can defend against microbial invaders, we could develop novel antimicrobial therapies that enhance mitochondrial functions or exploit their nutrient-blocking capabilities to combat infections.