About: HSPA9 is a research topic. Over the lifetime, 1266 publications have been published within this topic receiving 71654 citations. The topic is also known as: CSA & GRP-75.
TL;DR: A method that detects proteins capable of interacting with a known protein and that results in the immediate availability of the cloned genes for these interacting proteins is described and could be readily extended to mammalian proteins.
Abstract: We describe a method that detects proteins capable of interacting with a known protein and that results in the immediate availability of the cloned genes for these interacting proteins. Plasmids are constructed to encode two hybrid proteins. One hybrid consists of the DNA-binding domain of the yeast transcriptional activator protein GAL4 fused to the known protein; the other hybrid consists of the GAL4 activation domain fused to protein sequences encoded by a library of yeast genomic DNA fragments. Interaction between the known protein and a protein encoded by one of the library plasmids leads to transcriptional activation of a reporter gene containing a binding site for GAL4. We used this method with the yeast SIR4 protein, which is involved in the transcriptional repression of yeast mating type information. (i) We used the two-hybrid system to demonstrate that SIR4 can form homodimers. (ii) A small domain consisting of the C terminus of SIR4 was shown to be sufficient to mediate this interaction. (iii) We screened a library to detect hybrid proteins that could interact with the SIR4 C-terminal domain and identified SIR4 from this library. This approach could be readily extended to mammalian proteins by the construction of appropriate cDNA libraries in the activation domain plasmid.
TL;DR: It is demonstrated for the first time that expression of the protein in MA-10 cells in the absence of hormone stimulation is sufficient to induce steroid production and it is proposed that this protein is required in the acute regulation of steroidogenesis.
TL;DR: It is demonstrated that MRPs represent an evolutionarily conserved protein family that ties the mitochondrial ribosome and mitonuclear protein imbalance to the mitochondrial unfolded protein response, an overarching longevity pathway across many species.
Abstract: Longevity is regulated by a network of closely linked metabolic systems. We used a combination of mouse population genetics and RNA interference in Caenorhabditis elegans to identify mitochondrial ribosomal protein S5 (Mrps5) and other mitochondrial ribosomal proteins as metabolic and longevity regulators. MRP knockdown triggers mitonuclear protein imbalance, reducing mitochondrial respiration and activating the mitochondrial unfolded protein response. Specific antibiotics targeting mitochondrial translation and ethidium bromide (which impairs mitochondrial DNA transcription) pharmacologically mimic mrp knockdown and extend worm lifespan by inducing mitonuclear protein imbalance, a stoichiometric imbalance between nuclear and mitochondrially encoded proteins. This mechanism was also conserved in mammalian cells. In addition, resveratrol and rapamycin, longevity compounds acting on different molecular targets, similarly induced mitonuclear protein imbalance, the mitochondrial unfolded protein response and lifespan extension in C. elegans. Collectively these data demonstrate that MRPs represent an evolutionarily conserved protein family that ties the mitochondrial ribosome and mitonuclear protein imbalance to the mitochondrial unfolded protein response, an overarching longevity pathway across many species.
TL;DR: The mechanism by which ATFS-1 (activating transcription factor associated with stress–1) senses mitochondrial stress and communicates with the nucleus during the mitochondrial unfolded protein response (UPRmt) in Caenorhabditis elegans is examined and it is found that the key point of regulation is the mitochondrial import efficiency of ATfs-1.
Abstract: To better understand the response to mitochondrial dysfunction, we examined the mechanism by which ATFS-1 (activating transcription factor associated with stress–1) senses mitochondrial stress and communicates with the nucleus during the mitochondrial unfolded protein response (UPRmt) in Caenorhabditis elegans. We found that the key point of regulation is the mitochondrial import efficiency of ATFS-1. In addition to a nuclear localization sequence, ATFS-1 has an N-terminal mitochondrial targeting sequence that is essential for UPRmt repression. Normally, ATFS-1 is imported into mitochondria and degraded. However, during mitochondrial stress, we found that import efficiency was reduced, allowing a percentage of ATFS-1 to accumulate in the cytosol and traffic to the nucleus. Our results show that cells monitor mitochondrial import efficiency via ATFS-1 to coordinate the level of mitochondrial dysfunction with the protective transcriptional response.
TL;DR: A nuclear encoded mitochondrial heat-shock protein hsp60 is required for the assembly into oligomeric complexes of proteins imported into the mitochondrial matrix.
Abstract: A nuclear encoded mitochondrial heat-shock protein hsp60 is required for the assembly into oligomeric complexes of proteins imported into the mitochondrial matrix. hsp60 is a member of the 'chaperonin' class of protein factors, which include the Escherichia coli groEL protein and the Rubisco subunit-binding protein of chloroplasts.