Satellite III (1q12) Copy Number Variation in Cultured Human Skin Fibroblasts from Schizophrenic Patients and Healthy Controls.

BACKGROUND: The chromosome 1q12 region harbors the genome's largest pericentromeric heterochromatin domain that includes tandemly repeated satellite III DNA [SatIII (1)]. Increased SatIII (1) copy numbers have been found in cultured human skin fibroblasts (HSFs) during replicative senescence. The aim of this study was to analyze the variation in SatIII (1) abundance in cultured HSFs at early passages depending on the levels of endogenous and exogenous stress. METHODS: We studied 10 HSF cell lines with either high (HSFs from schizophrenic cases, n = 5) or low (HSFs from healthy controls, n = 5) levels of oxidative stress. The levels of endogenous stress were estimated by the amounts of reactive oxygen species, DNA damage markers (8-hydroxy-2'-deoxyguanosine, gamma-H2A histone family member X), pro- and antioxidant proteins (NADPH oxidase 4, superoxide dismutase 1, nuclear factor erythroid 2-related factor 2), and proteins that regulate apoptosis and autophagy (B-cell lymphoma 2 [Bcl-2], Bcl-2-associated X protein, light chain 3). SatIII (1) copy numbers were measured using the nonradioactive quantitative hybridization technique. For comparison, the contents of telomeric and ribosomal RNA gene repeats were determined. RNASATIII (1 and 9) were quantified using quantitative Polymerase Chain Reaction (PCR). RESULTS: Increased SatIII (1) contents in DNA from confluent HSFs were positively correlated with increased oxidative stress. Confluent cell cultivation without medium replacement and heat shock induced a decrease of SatIII (1) in DNA in parallel with a decrease in RNASATIII (1) and an increase in RNASATIII (9). CONCLUSIONS: During HSF cultivation, cells with increased SatIII (1) content accumulated in the cell pool under conditions of exaggerated oxidative stress. This fraction of cells decreased after the additional impact of exogenous stress. The process seems to be oscillatory.

Antipsychotics Affect Satellite III (1q12) Copy Number Variations in the Cultured Human Skin Fibroblasts.

The fragment of satellite III (f-SatIII) is located in pericentromeric heterochromatin of chromosome 1. Cell with an enlarged f-SatIII block does not respond to various stimuli and are highly stress-susceptible. The fraction of f-SatIII in the cells of schizophrenia patients changed during antipsychotic therapy. Therefore, antipsychotics might reduce the f-SatIII content in the cells. We studied the action of haloperidol, risperidone and olanzapine (3 h, 24 h, 96 h) on human skin fibroblast lines (n = 10). The f-SatIII contents in DNA were measured using nonradioactive quantitative hybridization. RNASATIII were quantified using RT-qPCR. The levels of DNA damage markers (8-oxodG, γ-H2AX) and proteins that regulate apoptosis and autophagy were determined by flow cytometry. The antipsychotics reduced the f-SatIII content in DNA and RNASATIII content in RNA from HSFs. After an exposure to the antipsychotics, the autophagy marker LC3 significantly increased, while the apoptosis markers decreased. The f-SatIII content in DNA positively correlated with RNASATIII content in RNA and with DNA oxidation marker 8-oxodG, while negatively correlated with LC3 content. The antipsychotics arrest the process of f-SatIII repeat augmentation in cultured skin fibroblasts via the transcription suppression and/or through upregulated elimination of cells with enlarged f-SatIII blocks with the help of autophagy.