Humanin was first discovered as a cDNA-encoded 24-amino-acid (aa) peptide that inhibited apoptosis in brain cells upon exposure to presenilin mutations linked to familial Alzheimer’s disease or amyloid- protein. A cysteine at position 8 of the Humanin peptide was essential for its anti-apoptotic action in a mutagenesis study. Apoptosis-inducing Bax (Bcl-2 associated X protein) has been demonstrated to interact with Humanin. Bax is inhibited from moving from the cytosol to the mitochondria by Humanin. Suppressing cytochrome c release in vitro and inhibiting Bax interaction with isolated mitochondria are two additional effects of Humanin peptides.
As mitochondria provide energy and regulate cell death in response to complicated signals, they have been primarily seen as ‘end-function’ organelles. As cellular entities in their own right, mitochondria relay information back to the cell and establish fundamental cellular policies. Collectively referred to as “retrograde signals,” these cues originate either in the nuclear genome or as byproducts of mitochondrial metabolism. This article will discuss Humanin, the first short peptide of a possible collection of mitochondria-derived peptides, which displays potent cytoprotective activities against various stress and disease types. Humanin and other retrograde signal peptides generated from mitochondria may help researchers locate genes and peptides that may be useful in diagnosing and treating human illness.
Biology and function of mitochondria
Mitochondria are thought to have originated as endosymbionts with eukaryotic host cells from -proteobacteria. Eukaryotic evolution was drastically altered when oxygen was used to generate energy and biosynthetic precursors in large quantities, a feat made possible by the mitochondria (proto-mitochondrion). Mitochondria are prokaryotic, making them the only intracellular organelles with their genome. Because of the loss or transfer of the vast majority of the original bacterial genes to the nucleus, only 13 full-size protein-encoding genes necessary for oxidative phosphorylation remain in the genome. Investigating the possible function this region of the human genome plays in aging, cancer, diabetes, deafness, and neurodegeneration has just begun.
Energy production, control of programmed cell death (apoptosis), biosynthetic precursors, synthesis of heme and Fe-S clusters, maintenance of ion homeostasis, and production of reactive oxygen species are just a few critical cellular functions out by mitochondria.
Despite their essential roles, mitochondria’s transmission of information to the host cell remains poorly understood. This post discusses a revolutionary idea about a new kind of mitochondrial communication used to control cellular activities and cell destiny.
Peptides derived from mitochondria act as regressive signaling molecules.
Retrograde signaling describes how mitochondria relay information to the rest of the cell. Calcium ion (Ca2+), cytochrome C (Cyt C), and reactive oxygen species (ROS) are classic examples of mitochondrial messengers documented in the literature. Mitochondrial DNA-encoded proteins (MDP) are a newly discovered class of retrograde signals. Humanin, a kind of MDP, may have several bodily functions, including an endocrine hormone and an intracellular component that affects cell proliferation, death, and metabolism.
The idea of mitochondria-to-nucleus-and-beyond retrograde signaling
Conventional wisdom is that mitochondria are “end-function” organelles, meaning they respond to cellular signals by controlling energy generation and apoptosis. But maintaining cellular homeostasis requires continuous and dynamic communication between the mitochondria and the nucleus about the control of gene expression. This biological mechanism is highly conserved from essential yeast to humans, collectively referred to as retrograde signaling. It involves mitochondria initiating communication events that signal and control many cellular components in average, stress, and disease states.
The number of retrograde signaling molecules and signaling cascades that have been studied is few. Cytochrome C, reactive oxygen species, calcium, iron, nitric oxide, carbon monoxide, and carbon monoxide are all mentioned here. Specifically, a fascinating C. Elegans investigation demonstrated non-canonical signals exported from mitochondria in response to proteotoxic assaults. However, they were not mitochondrially encoded peptides but rather proteolysis-derived, degraded matrix protein fragments from the nuclear genome that are subsequently imported into the mitochondria. They, like cytochrome C, are nuclear-encoded protein products of the mitochondria that are delivered back to the cell as retrograde signals.
Furthermore, mtDNA itself may serve as a message. According to new research, inhibition of autophagy leads to mitochondrial malfunction and mtDNA export to the cytosol through enhanced mitochondrial membrane permeability transition (MPT), which activates the caspase-1 inflammasome. Buy Humanin peptide if you are a researcher.