Proteasome Inhibition Diminishes the Formation of Neutrophil Extracellular Traps and Prevents the Death of Cardiomyocytes in Coculture with Activated Neutrophils during Anoxia-Reoxygenation.

Objective: Polymorphic mononuclear neutrophils (PMN) are very important cells participating in nonspecific defense of the organism. Among their well-known functions, the formation of neutrophil extracellular traps (NET) is interesting and potentially dangerous for the mechanisms of other cells. Ubiquitin-dependent proteasomal proteolysis is a very important regulator of all cellular activities, but the role of proteasomal proteolysis in NET formation has not been investigated.

Does proteasome regulate the level of microRNA-1 in cardiomyocytes? Application to anoxia-reoxygenation.

Proteasome and microRNAs play a critical role in almost all processes in a living organism, including pathology of the heart; however, their interaction is still in question. In the present study, we have found that proteasome inhibitor provoked increase of mature but not immature microRNA-1 in cultured cardiomyocytes, and tested the hypothesis that mature microRNA-1 can be a substrate for endonuclease activity of proteasome. In our in vitro experiments, we have found that proteasome fraction II is able to degrade both mature and primary but not precursor microRNA-1.

Mature and immature microRNA ratios in cultured rat cardiomyocytes during anoxia-reoxygenation.

Background: The critical role of microRNAs (miRNAs) in the global control of gene expression in the heart has recently been postulated; however, the mechanisms of miRNA regulation in cardiac pathology are not clear.

Objective: To evaluate the levels of miR-1, miR-208a and miR-29a expressed in neonatal rat cardiomyocytes during anoxia-reoxygenation (AR).

Methods: Reverse transcription coupled with real-time polymerase chain reaction was used to evaluate the level of mature and immature miRNAs in cardiomyocyte culture during AR.