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The role of exosomes in communication between adipose and cardiac tissue
Novotná, Denisa Regine ; Zouhar, Petr (advisor) ; Kašík, Petr (referee)
Extracellular vesicles, including exosomes, represent an important, newly identified, factor in the information transmission between individual cells and organs of a multicellular organism. Usually, exosomes contain nucleic acids, proteins and even whole organelles such as mitochondria. The exosomes production takes place, among others, in adipocytes of adipose tissue. Because adipose tissue is the main repository of stored lipids, its metabolism and the functionality of its mitochondria react sensitively e.g. to nutritional conditions. Recent studies have demonstrated that exosome secretion from adipose tissue may play a pivotal role in the progression of metabolic syndrome. In hypertrophied tissue, mitochondria fail, and adipocytes dispose of them by secreting them as exosomes. The majority of these exosomes with damaged mitochondria are directly taken up by macrophages within the adipose tissue. However, a subset of them can escape into the circulation and reach the heart. The uptake of these exosomes by the myocardium and the incorporation of damaged mitochondria into its own mitochondrial network may have surprisingly positive effects for increasing resistance to damage in infarction. Furthermore, exosomes may also play an important role in ridding brown adipose tissue and other cells of...
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Exosome and its role in RNA metabolism of budding yeast S. cerevisiae
Holická, Eliška ; Půta, František (advisor) ; Groušl, Tomáš (referee)
Exosome is a protein complex present in the yeast nucleus and cytoplasm, which participates in RNA degradation, processing and turnover. The core of exosome consists of nine catalytically inactive subunits, which physically associate with RNA nuclease Rrp44. The function of exosome is dependent on many cofactors or facultatively associated enzymes, and these associations provide high versatility of the complex. In different compartments the complex works by other means and plays a role in distinct processes. In nucleus, exosome acts mainly in pre-RNA processing, whereas in cytoplasm its major role is to degrade native mRNA. Nevertheless, in all of these processes, its general role is the 3' exonucleolytic cleavage of single-stranded RNA. Exosome has homologs in many various kinds of organisms - e. g. different types of bacterial nucleases, archeal exosome, human PM-Scl complex (or exosome), which implicates high conservation of this degradation machinery. Thus, it is very likely that some exosome components lost their original function over the evolution, more than that the yeast exosome is an evolutionary innovation.
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