Micro-RNA30c Negatively Regulates REDD1 Expression in Human Hematopoietic and Osteoblast Cells after Gamma-Irradiation

Abstract

We recently demonstrated that a novel cell stress response gene REDD1 protects human fetal osteoblast cell line (hFOB) cells from γ-radiation-induced premature senescence. Here we show that levels of endogenous REDD1 are very low in human hematopoietic progenitor CD34+ cells regardless of radiation, but highly expressed in differentiated hematopoietic cells (14 day cultured CD34+ cells) in response to radiation, which might be associated with radiation tolerance of the latter cells. To further understand the mechanisms of radiation-induced damage in different cells, microRNA (miRNA)-arrays were performed using purified miRNAs from CD34+ and hFOB cells before and post-irradiation and real-time reverse transcription (RT)-PCR was used to validate the expression profiles of miRNAs in the radiation-damaged cells. The results indicate that γ-radiation downregulated 16 miRNAs in CD34+ cells and 14 in hFOB cells. Radiation-induced upregulation was observed for 15 miRNAs in CD34+ cells and 18 miRNAs in hFOB cells. The profiles of radiation-induced miRNA expression were completely different in CD34+ vs. hFOB cells. Radiation up-regulated miRNA (miR)-30b, miR-30c and miR-30d in CD34+ cells, whereas it inhibited miR-30c expression in hFOB cells. Since miR-30 has potential target sites located in the 3′untranslated region (UTR) of the REDD1 gene and radiation regulated miR-30c expression in both CD34+ and hFOB cells, we further explored the effects of miR-30c on REDD1 expression using miR-30c inhibitor and precursor (pre-miR-30c). The results show that pre-miR-30c transfection suppressed REDD1 expression in 14 day cultured CD34+ cells and hFOB cells and resulted in hFOB cell death. In contrast, inhibition of miR-30c expression significantly enhanced clonogenicity in CD34+ cells. Our data suggest that CD34+ and hFOB cells have different miRNA expression patterns after irradiation and miR-30c plays a key role in radiation-induced cell damage which might be through regulation of REDD1 expression.

Gamma-Tocotrienol Modulates Radiation-Induced MicroRNA Expression in Mouse Spleen

“…Ionizing radiation is known to induce cellular stress by generating free radicals, which in turn cause DNA damage. Damaged DNA modulates an array of miR expression in a p53-dependent and -independent manner, as evident in in vitro (17, 21–23) and in vivo (18, 24) studies. MiR-34a, which is a direct target of p53, was reported to show potent anti-proliferative effects.…”

“…Plasma miRNA profile is highly predictive of different levels of radiation exposure and can serve as biomarkers to assess radiation dose after mass casualty scenarios (16, 20). Serum miR-150, a microRNA abundant in lymphocytes, exhibits a dose- and time-dependent decrease in expression after irradiation and has therefore been regarded as a sensitive biomarker for radiation-induced lymphocyte depletion and bone marrow damage (17). Ionizing radiation is known to induce cellular stress by generating free radicals, which in turn cause DNA damage.…”

Estrogen Regulates the Tumour Suppressor MiRNA-30c and Its Target Gene, MTA-1, in Endometrial Cancer

“…Currently, metastasis-associated gene-1 (MTA-1)[17], KRAS[20], DLL4[31], TWF1, vimentin[21], BCL9[19], REDD1[32], PAI-1[33] and CTGF[34] have been identified as targets of miR-30c, and SERPINE1[28], NYH11, GPRASP2 DDR2[16], PPARGC1B, Makorin-3, UBAC1, PTPDC1[22] snail1[35], p53[36]are potential targets that remain to be validated. Because miR-30c exhibits a relative decrease in expression from normal endometrium to atypical hyperplasia to cancer, and because the role of miR-30c in EC remains unknown, we conducted an investigation of the role of miR-30c in EC.…”

Regulation of protein and mRNA expression of the mTORC1 repressor REDD1 in response to leucine and serum

“…Similar results were obtained in a model of gamma-irradiated hematopoetic and osteoblastic cells, where gamma-irradiation induced upregulation of miR-30c and its overexpression led to a reduction in REDD1 expression. A potential binding site for miR-30c was also identified in the 3'-UTR of the REDD1 gene [21]. These data demonstrate differential expression of miRNA's under distinct physiological and pathological conditions and suggest that novel mechanisms of REDD1 suppression exist to promote cell survival and will likely warrant further investigation.…”