Bcl-2, encoded in humans by the BCL2 gene, is the founding member of the Bcl-2 family of regulator proteins that regulate cell death (apoptosis), by either inhibiting (anti-apoptotic) or inducing (pro-apoptotic) apoptosis. It was the first apoptosis regulator identified in any organism.
The apoptosome is a large quaternary protein structure formed in the process of apoptosis. Its formation is triggered by the release of cytochrome c from the mitochondria in response to an internal (intrinsic) or external (extrinsic) cell death stimulus. Stimuli can vary from DNA damage and viral infection to developmental cues such as those leading to the degradation of a tadpole's tail.
FAS-associated death domain protein, also called MORT1, is encoded by the FADD gene on the 11q13.3 region of chromosome 11 in humans.
Apoptosis signal-regulating kinase 1 (ASK1) also known as mitogen-activated protein kinase 5 (MAP3K5) is a member of MAP kinase family and as such a part of mitogen-activated protein kinase pathway. It activates c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinases in a Raf-independent fashion in response to an array of stresses such as oxidative stress, endoplasmic reticulum stress and calcium influx. ASK1 has been found to be involved in cancer, diabetes, rheumatoid arthritis, cardiovascular and neurodegenerative diseases.
Mitofusin-2 is a protein that in humans is encoded by the MFN2 gene. Mitofusins are GTPases embedded in the outer membrane of the mitochondria. In mammals MFN1 and MFN2 are essential for mitochondrial fusion. In addition to the mitofusins, OPA1 regulates inner mitochondrial membrane fusion, and DRP1 is responsible for mitochondrial fission.
DnaJ homolog subfamily A member 3, mitochondrial, also known as Tumorous imaginal disc 1 (TID1), is a protein that in humans is encoded by the DNAJA3 gene on chromosome 16. This protein belongs to the DNAJ/Hsp40 protein family, which is known for binding and activating Hsp70 chaperone proteins to perform protein folding, degradation, and complex assembly. As a mitochondrial protein, it is involved in maintaining membrane potential and mitochondrial DNA (mtDNA) integrity, as well as cellular processes such as cell movement, growth, and death. Furthermore, it is associated with a broad range of diseases, including neurodegenerative diseases, inflammatory diseases, and cancers.
Peroxiredoxin-5 (PRDX5), mitochondrial is a protein that in humans is encoded by the PRDX5 gene, located on chromosome 11.
Dynamin-1-like protein is a GTPase that regulates mitochondrial fission. In humans, dynamin-1-like protein, which is typically referred to as dynamin-related protein 1 (Drp1), is encoded by the DNM1L gene and is part of the dynamin superfamily (DSP) family of proteins.
28S ribosomal protein S29, mitochondrial, also known as death-associated protein 3 (DAP3), is a protein that in humans is encoded by the DAP3 gene on chromosome 1. This gene encodes a 28S subunit protein of the mitochondrial ribosome (mitoribosome) and plays key roles in translation, cellular respiration, and apoptosis. Moreover, DAP3 is associated with cancer development, but has been observed to aid some cancers while suppressing others.
Death-associated protein kinase 3 is an enzyme that in humans is encoded by the DAPK3 gene.
E3 ubiquitin-protein ligase MARCH5, also known as membrane-associated ring finger (C3HC4) 5, is an enzyme that, in humans, is encoded by the MARCH5 gene. It is localized in the mitochondrial outer membrane and has four transmembrane domains.
Voltage-dependent anion-selective channel protein 2 is a protein that in humans is encoded by the VDAC2 gene on chromosome 10. This protein is a voltage-dependent anion channel and shares high structural homology with the other VDAC isoforms. VDACs are generally involved in the regulation of cell metabolism, mitochondrial apoptosis, and spermatogenesis. Additionally, VDAC2 participates in cardiac contractions and pulmonary circulation, which implicate it in cardiopulmonary diseases. VDAC2 also mediates immune response to infectious bursal disease (IBD).
Voltage-dependent anion-selective channel protein 3 (VDAC3) is a protein that in humans is encoded by the VDAC3 gene on chromosome 8. The protein encoded by this gene is a voltage-dependent anion channel and shares high structural homology with the other VDAC isoforms. Nonetheless, VDAC3 demonstrates limited pore-forming ability and, instead, interacts with other proteins to perform its biological functions, including sperm flagella assembly and centriole assembly. Mutations in VDAC3 have been linked to male infertility, as well as Parkinson's disease.
Mitochondrial biogenesis is the process by which cells increase mitochondrial numbers. It was first described by John Holloszy in the 1960s, when it was discovered that physical endurance training induced higher mitochondrial content levels, leading to greater glucose uptake by muscles. Mitochondrial biogenesis is activated by numerous different signals during times of cellular stress or in response to environmental stimuli, such as aerobic exercise.
Mitochondrial fission is the process where mitochondria divide or segregate into two separate mitochondrial organelles. Mitochondrial fission is counteracted by the process of mitochondrial fusion, whereby two separate mitochondria can fuse together to form a large one. Mitochondrial fusion in turn can result in elongated mitochondrial networks. Both mitochondrial fission and fusion are balanced in the cell, and mutations interfering with either processes are associated with a variety of diseases. Mitochondria can divide by prokaryotic binary fission and since they require mitochondrial DNA for their function, fission is coordinated with DNA replication. Some of the proteins that are involved in mitochondrial fission have been identified and some of them are associated with mitochondrial diseases. Mitochondrial fission has significant implications in stress response and apoptosis.
Mitochondrial fission factor (Mff) is a protein that in humans is encoded by the MFF gene. Its primary role is in controlling the division of mitochondria. Mitochondrial morphology changes by continuous fission in order to create interconnected network of mitochondria. This activity is crucial for normal function of mitochondria. Mff is anchored to the mitochondrial outer membrane through the C-terminal transmembrane domain, extruding the bulk of the N-terminal portion containing two short amino acid repeats in the N-terminal half and a coiled-coil domain just upstream of the transmembrane domain into the cytosol. It has also been shown to regulate peroxisome morphology.
Mitochondria are dynamic organelles with the ability to fuse and divide (fission), forming constantly changing tubular networks in most eukaryotic cells. These mitochondrial dynamics, first observed over a hundred years ago are important for the health of the cell, and defects in dynamics lead to genetic disorders. Through fusion, mitochondria can overcome the dangerous consequences of genetic malfunction. The process of mitochondrial fusion involves a variety of proteins that assist the cell throughout the series of events that form this process.
Mitochondrial E3 ubiquitin protein ligase 1 (MUL1) is an enzyme that in humans is encoded by the MUL1 gene on chromosome 1. This enzyme localizes to the outer mitochondrial membrane, where it regulates mitochondrial morphology and apoptosis through multiple pathways, including the Akt, JNK, and NF-κB. Its proapoptotic function thus implicates it in cancer and Parkinson's disease.
Mitochondrial elongation factor 2 is a protein that in humans is encoded by the MIEF2 gene.
David A. Hood is a Canadian professor, exercise physiologist, and Director of the Muscle Health Research Centre at York University. A holder of an NSERC Tier I Canada Research Chair in Cell Physiology, Hood is credited with making significant research advances in understanding of the biology of exercise, mitochondria and muscle health.
