Anti-DGCR8 monoclonal antibody, clone 5H4

Recent investigations have emphasized the role of miRNA biogenesis proteins in the synthesis of non-coding RNA when double-strand DNA breaks are induced by ionizing radiations. However, the role of these non-coding RNA and their regulation in response to doxorubicin-induced DNA damage is not known. In this paper, BRG1 and SMARCAL1, members of the ATP-dependent chromatin remodelling family, are shown to co-regulate the transcription of DROSHA, DGCR8, and DICER in response to double-strand DNA breaks induced by doxorubicin. Both BRG1 and SMARCAL1 are needed for the upregulation of the three miRNA biogenesis genes as absence of BRG1 results in downregulation of DGCR8 and DICER while absence of SMARCAL1 results in downregulation of DROSHA. These two proteins act in coordination to upregulate expression of DROSHA, DGCR8, and DICER when cells are treated with doxorubicin. This transcriptional regulation of the miRNA biogenesis proteins is needed for the formation of 53BP1 foci as downregulation of either BRG1 or SMARCAL1 reduced the number of 53BP1 foci in DNA damaged cells. The foci formation was restored when the downregulated cells were treated with ncRNA purified from doxorubicin treated HeLa cells. From the results obtained, we conclude that the regulation of miRNA biogenesis proteins by SMARCAL1 and BRG1 is needed for the formation of non-coding RNA and thus, 53BP1 foci in response to doxorubicin-induced DNA damage.

We aimed to determine the levels of microRNAs (miRNAs) in sera and HDL of acute coronary syndrome (ACS) compared to stable angina (SA) patients with/ without hyperglycemia, and evaluate comparatively the functional effect of these sera on the processing machinery proteins (Drosha, DGCR8, Dicer) and miRNAs production in human macrophages. MiRNAs levels in sera and HDL from 35 SA and 72 ACS patients and 30 healthy subjects were measured by using microRNA TaqMan assays. MiR-223, miR-92a, miR-486, miR-122, miR125a and miR-146a levels were higher in the hyperglycemic ACS compared to normoglycemic sera. MiR-223 and miR-486 prevailed in HDL2, while miR-92a predominated in HDL3, all three miRNAs discriminating between ACS and SA patients; their levels were increased in HDL from hyperglycemic ACS patients versus normoglycemic ones. The incubation of human macrophages with sera from ACS and SA patients showed that all patients' sera induced an increase of Drosha, DGCR8 and Dicer expressions and of selected miRNAs levels compared to control sera, the effect being higher in the case of hyperglycemic versus normoglycemic ACS sera. The addition of glucose to SA and ACS sera increased Drosha, DGCR8 and Dicer expression and miRNAs levels in the exposed macrophages. In conclusion, hyperglycemia is associated with increased miR-223, miR-92a, miR-486 levels in HDL, which discriminate between ACS and SA patients. Exposure of human macrophages to ACS compared to SA sera determines the upregulation of Drosha, DGCR8 and Dicer expression and the increase of selected miRNAs production, the effect being augmented by an increased glucose concentration.