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. 2000 Jan 4;97(1):377–382. doi: 10.1073/pnas.97.1.377

Figure 4.

Figure 4

TSA removal results in rapid chromatin condensation and transgene silencing. (A) After 24-hour TSA treatment, cells were washed thoroughly and cultured in normal medium. DNaseI analysis of lacZ was performed at the indicated time points after removing TSA. The virally transduced lacZ gene became resistant to DNaseI digestion within 4 hours after TSA removal. (B) Measurement of transcription by nuclear run-on. Transcription of the lacZ gene is inhibited by 90% at 4 hours after TSA removal and completely inhibited by 12 hours after removal. (C) ClaI sensitivity assay of lacZ and APRT after removing TSA. (D) Comparison of DNaseI sensitivity and run-on transcription data after TSA removal. These results suggest that chromatin condensation and transcriptional silencing occur rapidly at the rAAV/CMVlacZ locus after TSA removal. (E) Comparison of ClaI sensitivity and nuclear run-on transcription data of lacZ gene. These data confirm the results of the DNaseI sensitivity experiments in D. (F) Comparison of ClaI sensitivity and run-on transcription data of the APRT gene. Chromatin accessibility is high (>50%) for this constitutively active gene before and after TSA removal.