Cristae formation—linking ultrastructure and function of mitochondria

Abstract

Mitochondria are double-membrane enclosed eukaryotic organelles with a central role in numerous cellular functions. The ultrastructure of mitochondria varies considerably between tissues, organisms, and the physiological state of cells. Alterations and remodeling of inner membrane structures are evident in numerous human disorders and during apoptosis. The inner membrane is composed of two subcompartments, the cristae membrane and the inner boundary membrane. Recent advances in electron tomography led to the current view that these membrane domains are connected by rather small tubular structures, termed crista junctions. They have been proposed to regulate the dynamic distribution of proteins and lipids as well as of soluble metabolites between individual mitochondrial subcompartments. One example is the release of cytochrome c upon induction of apoptosis. However, only little is known on the molecular mechanisms mediating the formation and maintenance of cristae and crista junctions. Here we review the current knowledge of the factors that determine cristae morphology and how the latter is linked to mitochondrial function. Further, we formulate several theoretical models which could account for the de novo formation of cristae as well as their propagation from existing cristae.

Loss of OPA1 disturbs cellular calcium homeostasis and sensitizes for excitotoxicity

“…9,10 Electron microscopy (EM) analyses indicate that OPA1 loss causes abnormal mitochondrial ultrastructure with cristae disorganization. [9][10][11] Interaction of OPA1 with membranes can induce a structural remodeling into tubules, 12 a feature characteristic of crista junctions, [13][14][15] supporting the proposal that OPA1 is a key component of these junctions. [16][17][18] Because crista junctions are normally uniform, a change in their size may indicate alteration in mitochondrial functional status.…”

Mic60/Mitofilin determines MICOS assembly essential for mitochondrial dynamics and mtDNA nucleoid organization

“…[3][4][5][6][7][8] The mitochondrial inner boundary and cristae membrane are physically separated by cristae junctions, which are narrow tubular or slot-like structure. 4,9 The mitochondrial cristae are arranged in regular arrays and are the main sites of ATP production in the mitochondria, but the molecules that are associated with the maintenance of cristae architecture still remain elusive. Recently, several groups identified a large protein complex, MICOS complex (mitochondrial contact site and cristae organizing system; previously named MINOS, MitOS, Mitofilin or Fcj1 complex ), that has a crucial role in the formation of cristae junctions, contact sites to the outer membrane, and the organization of inner membrane.…”

“…1,2 In contrast, the mitochondrial inner membrane consists of two morphologically distinct regions: the inner boundary membrane is in close proximity to the outer membrane and the cristae membranes that are large tubular invaginations. [3][4][5][6][7][8] The mitochondrial inner boundary and cristae membrane are physically separated by cristae junctions, which are narrow tubular or slot-like structure. 4,9 The mitochondrial cristae are arranged in regular arrays and are the main sites of ATP production in the mitochondria, but the molecules that are associated with the maintenance of cristae architecture still remain elusive.…”

Observation on the ultrastructure morphology of HeLa cells treated with ethanol: Statistical analysis

“…of cytochrome c that is stored within the intracristal space [35]. However, mitochondria are best known for their role in cellular energy production but they are also essential for diverse metabolic functions such as heat production, calcium and iron homeostasis as well as the biosynthesis of heme, pyrimidines, and steroids [34,36,37].…”