Limits...
Low dose radiation induced senescence of human mesenchymal stromal cells and impaired the autophagy process.

Alessio N, Del Gaudio S, Capasso S, Di Bernardo G, Cappabianca S, Cipollaro M, Peluso G, Galderisi U - Oncotarget (2015)

Bottom Line: Individuals may be exposed to low doses of radiation either intentionally for medical purposes or accidentally, such as those exposed to radiological terrorism or those who live near illegal radioactive waste dumpsites.We studied the effects of low dose radiation on human bone marrow mesenchymal stromal cells (MSC), which contain a subpopulation of stem cells able to differentiate in bone, cartilage, and fat; support hematopoiesis; and contribute to body's homeostasis.The main outcome of low radiation exposure, besides reduction of cell cycling, is the triggering of senescence, while the contribution to apoptosis is minimal.We hypothesize that the autophagy prevented radiation deteriorative processes, and its decline contributed to senescence.An increase in ATM staining one and six hours post-irradiation and return to basal level at 48 hours, along with persistent gamma-H2AX staining, indicated that MSC properly activated the DNA repair signaling, though some damages remained unrepaired, mainly in non-cycling cells.This suggested that the impaired DNA repair capacity of irradiated MSC seemed mainly related to the reduced activity of a non-homologous end-joining (NHEJ) system rather than HR (homologous recombination).

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Medicine, Biotechnology and Molecular Biology Section, Second University of Naples, Naples 80138, Italy.

ABSTRACT
Low doses of radiation may have profound effects on cellular function. Individuals may be exposed to low doses of radiation either intentionally for medical purposes or accidentally, such as those exposed to radiological terrorism or those who live near illegal radioactive waste dumpsites.We studied the effects of low dose radiation on human bone marrow mesenchymal stromal cells (MSC), which contain a subpopulation of stem cells able to differentiate in bone, cartilage, and fat; support hematopoiesis; and contribute to body's homeostasis.The main outcome of low radiation exposure, besides reduction of cell cycling, is the triggering of senescence, while the contribution to apoptosis is minimal. We also showed that low radiation affected the autophagic flux. We hypothesize that the autophagy prevented radiation deteriorative processes, and its decline contributed to senescence.An increase in ATM staining one and six hours post-irradiation and return to basal level at 48 hours, along with persistent gamma-H2AX staining, indicated that MSC properly activated the DNA repair signaling, though some damages remained unrepaired, mainly in non-cycling cells. This suggested that the impaired DNA repair capacity of irradiated MSC seemed mainly related to the reduced activity of a non-homologous end-joining (NHEJ) system rather than HR (homologous recombination).

No MeSH data available.


Related in: MedlinePlus

Evaluation of DNA damage and repairPanels (A, B) – ATM immunostaining. Fluorescence photomicrographs shows a typical cell stained with anti-ATM (green) and Ki67 (red). Nuclei were counterstained with Hoechst 33342 (blue). A representative microscopic field for each treatment is shown. The mean percentage of ATM- and Ki67-positive cells is indicated in the graph (± SD, n = 3, *p < 0.05). Panels (C, D) – 53BP1 immunostaining. Fluorescence photomicrographs show cells stained with anti-53BP1 (green) and Ki67 (red). Nuclei were counterstained with Hoechst 33342 (blue). A representative microscopic field for each treatment is shown. The mean percentage of 53BP1- and Ki67-positive cells is indicated in the graph (± SD, n = 3, *p < 0.05). Panels (E, F) – RAD51 immunostaining. Fluorescence photomicrographs show cells stained with anti-RAD51 (green) and Ki67 (red). Nuclei were counterstained with Hoechst 33342 (blue). A representative microscopic field for each treatment is shown. The mean percentage of RAD51- and Ki67-positive cells is indicated in the graph (± SD, n = 3, *p < 0.05). Panels (G, H) – DNA-PK immunostaining. Fluorescence photomicrographs show cells stained with anti-DNA-PK (green) and Ki67 (red). Nuclei were counterstained with Hoechst 33342 (blue). A representative microscopic field for each treatment is shown. The mean percentage of DNA-PK- and Ki67-positive cells is indicated in the graph (± SD, n = 3, *p < 0.05).
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Figure 4: Evaluation of DNA damage and repairPanels (A, B) – ATM immunostaining. Fluorescence photomicrographs shows a typical cell stained with anti-ATM (green) and Ki67 (red). Nuclei were counterstained with Hoechst 33342 (blue). A representative microscopic field for each treatment is shown. The mean percentage of ATM- and Ki67-positive cells is indicated in the graph (± SD, n = 3, *p < 0.05). Panels (C, D) – 53BP1 immunostaining. Fluorescence photomicrographs show cells stained with anti-53BP1 (green) and Ki67 (red). Nuclei were counterstained with Hoechst 33342 (blue). A representative microscopic field for each treatment is shown. The mean percentage of 53BP1- and Ki67-positive cells is indicated in the graph (± SD, n = 3, *p < 0.05). Panels (E, F) – RAD51 immunostaining. Fluorescence photomicrographs show cells stained with anti-RAD51 (green) and Ki67 (red). Nuclei were counterstained with Hoechst 33342 (blue). A representative microscopic field for each treatment is shown. The mean percentage of RAD51- and Ki67-positive cells is indicated in the graph (± SD, n = 3, *p < 0.05). Panels (G, H) – DNA-PK immunostaining. Fluorescence photomicrographs show cells stained with anti-DNA-PK (green) and Ki67 (red). Nuclei were counterstained with Hoechst 33342 (blue). A representative microscopic field for each treatment is shown. The mean percentage of DNA-PK- and Ki67-positive cells is indicated in the graph (± SD, n = 3, *p < 0.05).

Mentions: Both low and high dose irradiation produced a significant number of ATM-positive cells one and six hours post treatment, but 48 hours post-IR, the number of positive cells decreased compared to the level observed in control cultures (Fig. 4A, B). This trend was noticed both in cycling (Ki67+) and resting cells (Ki67-).


Low dose radiation induced senescence of human mesenchymal stromal cells and impaired the autophagy process.

Alessio N, Del Gaudio S, Capasso S, Di Bernardo G, Cappabianca S, Cipollaro M, Peluso G, Galderisi U - Oncotarget (2015)

Evaluation of DNA damage and repairPanels (A, B) – ATM immunostaining. Fluorescence photomicrographs shows a typical cell stained with anti-ATM (green) and Ki67 (red). Nuclei were counterstained with Hoechst 33342 (blue). A representative microscopic field for each treatment is shown. The mean percentage of ATM- and Ki67-positive cells is indicated in the graph (± SD, n = 3, *p < 0.05). Panels (C, D) – 53BP1 immunostaining. Fluorescence photomicrographs show cells stained with anti-53BP1 (green) and Ki67 (red). Nuclei were counterstained with Hoechst 33342 (blue). A representative microscopic field for each treatment is shown. The mean percentage of 53BP1- and Ki67-positive cells is indicated in the graph (± SD, n = 3, *p < 0.05). Panels (E, F) – RAD51 immunostaining. Fluorescence photomicrographs show cells stained with anti-RAD51 (green) and Ki67 (red). Nuclei were counterstained with Hoechst 33342 (blue). A representative microscopic field for each treatment is shown. The mean percentage of RAD51- and Ki67-positive cells is indicated in the graph (± SD, n = 3, *p < 0.05). Panels (G, H) – DNA-PK immunostaining. Fluorescence photomicrographs show cells stained with anti-DNA-PK (green) and Ki67 (red). Nuclei were counterstained with Hoechst 33342 (blue). A representative microscopic field for each treatment is shown. The mean percentage of DNA-PK- and Ki67-positive cells is indicated in the graph (± SD, n = 3, *p < 0.05).
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Figure 4: Evaluation of DNA damage and repairPanels (A, B) – ATM immunostaining. Fluorescence photomicrographs shows a typical cell stained with anti-ATM (green) and Ki67 (red). Nuclei were counterstained with Hoechst 33342 (blue). A representative microscopic field for each treatment is shown. The mean percentage of ATM- and Ki67-positive cells is indicated in the graph (± SD, n = 3, *p < 0.05). Panels (C, D) – 53BP1 immunostaining. Fluorescence photomicrographs show cells stained with anti-53BP1 (green) and Ki67 (red). Nuclei were counterstained with Hoechst 33342 (blue). A representative microscopic field for each treatment is shown. The mean percentage of 53BP1- and Ki67-positive cells is indicated in the graph (± SD, n = 3, *p < 0.05). Panels (E, F) – RAD51 immunostaining. Fluorescence photomicrographs show cells stained with anti-RAD51 (green) and Ki67 (red). Nuclei were counterstained with Hoechst 33342 (blue). A representative microscopic field for each treatment is shown. The mean percentage of RAD51- and Ki67-positive cells is indicated in the graph (± SD, n = 3, *p < 0.05). Panels (G, H) – DNA-PK immunostaining. Fluorescence photomicrographs show cells stained with anti-DNA-PK (green) and Ki67 (red). Nuclei were counterstained with Hoechst 33342 (blue). A representative microscopic field for each treatment is shown. The mean percentage of DNA-PK- and Ki67-positive cells is indicated in the graph (± SD, n = 3, *p < 0.05).
Mentions: Both low and high dose irradiation produced a significant number of ATM-positive cells one and six hours post treatment, but 48 hours post-IR, the number of positive cells decreased compared to the level observed in control cultures (Fig. 4A, B). This trend was noticed both in cycling (Ki67+) and resting cells (Ki67-).

Bottom Line: Individuals may be exposed to low doses of radiation either intentionally for medical purposes or accidentally, such as those exposed to radiological terrorism or those who live near illegal radioactive waste dumpsites.We studied the effects of low dose radiation on human bone marrow mesenchymal stromal cells (MSC), which contain a subpopulation of stem cells able to differentiate in bone, cartilage, and fat; support hematopoiesis; and contribute to body's homeostasis.The main outcome of low radiation exposure, besides reduction of cell cycling, is the triggering of senescence, while the contribution to apoptosis is minimal.We hypothesize that the autophagy prevented radiation deteriorative processes, and its decline contributed to senescence.An increase in ATM staining one and six hours post-irradiation and return to basal level at 48 hours, along with persistent gamma-H2AX staining, indicated that MSC properly activated the DNA repair signaling, though some damages remained unrepaired, mainly in non-cycling cells.This suggested that the impaired DNA repair capacity of irradiated MSC seemed mainly related to the reduced activity of a non-homologous end-joining (NHEJ) system rather than HR (homologous recombination).

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Medicine, Biotechnology and Molecular Biology Section, Second University of Naples, Naples 80138, Italy.

ABSTRACT
Low doses of radiation may have profound effects on cellular function. Individuals may be exposed to low doses of radiation either intentionally for medical purposes or accidentally, such as those exposed to radiological terrorism or those who live near illegal radioactive waste dumpsites.We studied the effects of low dose radiation on human bone marrow mesenchymal stromal cells (MSC), which contain a subpopulation of stem cells able to differentiate in bone, cartilage, and fat; support hematopoiesis; and contribute to body's homeostasis.The main outcome of low radiation exposure, besides reduction of cell cycling, is the triggering of senescence, while the contribution to apoptosis is minimal. We also showed that low radiation affected the autophagic flux. We hypothesize that the autophagy prevented radiation deteriorative processes, and its decline contributed to senescence.An increase in ATM staining one and six hours post-irradiation and return to basal level at 48 hours, along with persistent gamma-H2AX staining, indicated that MSC properly activated the DNA repair signaling, though some damages remained unrepaired, mainly in non-cycling cells. This suggested that the impaired DNA repair capacity of irradiated MSC seemed mainly related to the reduced activity of a non-homologous end-joining (NHEJ) system rather than HR (homologous recombination).

No MeSH data available.


Related in: MedlinePlus