Fig. 1.

Depletion of CDK12 triggers heterochromatin enrichment on euchromatic arms. (A and B) HP1 and H3K9me2 spread to euchromatic arms after CDK12 knockdown. Polytene chromosomes were squashed and stained with (A) anti-HP1 and (B) anti-H3K9me2. The relative fluorescence intensities of HP1 and H3K9me2 on the euchromatic arms based on raw data are shown in Right. Error bars indicate SD (n = 3). *P < 0.05; ***P < 0.001. (C) Western blot results showing that CDK12 depletion has no obvious effect on the level of HP1 or H3K9me2. Whole-tissue extracts were prepared from third-instar larvae. Antibodies specific for CDK12, HP1, and H3K9me2 were used. Antibodies against Actin and histone H3 were used as loading controls. Three independent replicates were performed. (D) The efficiency of CDK12 depletion was validated by immunostaining. Polytene chromosomes were labeled with anti-CDK12 (red). CON, control. (Scale bar: 10 μm.)