What element brings together intermediate filaments, mitochondria and desmosomes? I think it would be nice to know which of these organelles is responsible for initiating the association of the three to create the desmosomal mitochondria tether which is connected via intermediate filaments. Which?
1) Intermediate filaments can “tug” on mitochondrial shape (morphology). This is clearly evident in countless micrographs.
2) Intermediate filaments bind with the desmoplakin protein (part of the desmosome) and the latter bonds with the dense portion of the desmosome (plakophilin, plakoglobin) just adjacent to the plasmalemma (on the intracellular side) and the intracellular ends of desmocolin and desmoglein (the main proteins in the intercellular space).
3) Mitochondria as calcium buffers may have be important in regulating the calcium dependent adhesion molecules, desmocolin and desmoglein, in particular formation and reduction of desmosomes. This is a function seen in other intermediate filament mitochondria tethers as well.
4) Mitochondria provide energy as ATP.
5) Also, the flattened part of the mitochondrial membrane which is adjacent to the desmosomal – mitochondrial tether area with intermediate filaments would probably include mitochondrial membrane anchoring receptors.
6) If what is reported is true (longer mitochondria produce more energy) then those long three or four thered areas on a single mitochondria would be “really active” in terms of energy production). Arrowheads = des – mit tethers; tj = tight junction; bar = 100nm; RER along the top right of the image. Syrian hamster hepatocyte.
A LIST OF VARIOUS accepted functions for membrane-mitochondria-filament associations
a- apoptosis
b- lipid transport
c- autophagy
d- mitochondrial morphology
e- intercellular junctions
So this is a obviously going to be the short list…. thee will be many more functions to come.