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Welcome to the Henry Stewart Talks.
My name is Ayesha Saleem,
and I'm an Assistant Professor at
the Faculty of Kinesiology and Recreation Management at the University of Manitoba,
and a Principal Investigator at the Children's Hospital Research Institute of Manitoba.
The title of today's talk is mitochondrial diseases: an update.
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This is the outline for the talk today.
First, I will give some background information about
the mitochondria and its structural components.
Then, I will delve into the epidemiology of mitochondrial diseases.
I will follow that up by looking at adult-onset and then
childhood-onset mitochondrial diseases that are characterized
primarily by defects in mitochondrial and nuclear DNA, respectively.
Finally, I will explore the symptoms and
therapeutic options for mitochondrial diseases and finish
the talk by discussing a subset of
non-communicable diseases that are linked to dysfunctional mitochondria.
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So, about two billion years ago,
a single fusion event between
a prokaryotic and a eukaryotic cell may have
ultimately led to the presence of mitochondria within our cells today.
Mitochondria are tiny organelles found in
almost all the eukaryotic cells and are necessary for cell form and function.
Known as the powerhouse of the cell,
mitochondria are responsible for creating more than 90 percent of
cellular energy, or ATP, through oxidative phosphorylation.
In addition to their main role in energy production and metabolism,
mitochondria are the site for synthesis of iron-sulfur clusters,
steroid biosynthesis, and are involved in initiating apoptosis or programmed cell death,
production and removal of reactive oxygen species,
oxidation of fatty acids,
and regulation of calcium signaling.
Shown is a schematic of a mitochondrion.
Mitochondria are made of a double phospholipid layer,
an outer mitochondrial membrane and
an inner mitochondrial membrane that folds upon itself and creates cristae,
thereby maximizing surface area for chemical reactions.
That space between the two membranes is called the intermembrane space,
and the space enclosed by the inner mitochondrial membrane is known as the matrix.
Mitochondria are unique in that they are the only subcellular organelles to have
their own DNA that can be found inside
the matrix in close proximity to the electron transport chain.
Textbook depictions of mitochondria usually resort to a kidney bean-shaped structure.
In reality, mitochondria often exist in the form of
a reticular interconnected network as shown in the electron micrograph.
The dark structures are the mitochondria found inside a skeletal muscle fiber.
You can clearly appreciate the beautiful organization of cristae within
each mitochondrion that gives the mitochondria their characteristic wrinkled appearance.
The number of mitochondria per cell varies depending on the type of the cell.
