Figure 1.

Genomic microarray analysis of CENP-C and CENP-H binding domains in two independent 13q32/33 neocentromeres. (a) Ideogrammatic representation of the two neocentric chromosomes analyzed. From left to right: a normal chromosome 13, the invdup13q21 in IMS13q with a neocentromere in band 13q32, and the invdup13q21 in BBB with a neocentromere in band 13q33.1. An expansion of the 13q31.3 to 13q33.2 area included in the bacterial artificial chromosome (BAC) CHIP is shown. The position and size of each previously mapped centromere protein (CENP)-A domain from Alonso and coworkers [32] are indicated. (b) DNA obtained from chromatin immunoprecipitation (ChIP) using antibodies to CENP-C (circles) and CENP-H (triangles) from cell lines BBB and IMS13q was hybridized to a contiguous BAC microarray spanning 14 megabases (Mb) from 13q31.3 to 13q33.2. Shown across the bottom of the graph is the tiling path of the unique sequenced regions for each BAC, the previously determined CENP-A domains [32] in cell lines BBB and IMS13q, and the genes in the region. Three independent biologic replicates were performed for each ChIP from each cell line, and the scale normalized mean log₂ Cy-5:Cy-3 intensity ratios (ChIP to input) with standard error (SE) were plotted on the y-axis for each BAC. Positive intensity ratios were identified as those that were at least three times the standard deviation (SD) from the experimental mean (gray or black dashed lines; see Materials and methods). For cell line BBB, CENP-C ChIP, the experimental mean was 0 ± 0.82 SD. Positive values ≥ 2.5 (black dashed line) were as follows: alpha sat = 6.42 ± 0.39 SE and BAC RP11-46I10 = 4.66 ± 0.92 SE. BAC RP11-29B2 was slightly increased (1.18 ± 1.2 SE) but not statistically significantly. All other BACs ranged from -1.1 to ≤ 0.96. For cell line BBB, CENP-H ChIP, the experimental mean was -0.02 ± 0.75 SD. Positive values ≥ 2.2 (grey dashed line) were as follows: alpha sat = 4.92 ± 1.86 SE and BAC RP11-46I10 = 5.57 ± 0.77 SE. BAC RP11-29B2 was slightly increased (1.58 ± 0.71 SE) but not statistically significantly. All other BACs ranged from -1.27 to ≤ 1.03. For cell line IMS13q, CENP-C ChIP, the experimental mean was 0 ± 0.84 SD. Positive values ≥ 2.5 (black dashed line) were as follows: alpha sat = 5.26 ± 0.38 SE and BAC RP11-199B17 = 4.95 ± 0.86 SE. All other BACs ranged from -1.7 to ≤ 0.93. For cell line IMS13q, CENP-H, the experimental mean was 0.00 ± 0.64 SD. Positive values ≥ 1.9 (grey dashed line) were as follows: alpha sat = 2.63 ± 1.03 SE and BAC RP11-199B17 = 3.95 ± 1.06 SE. All other BACs ranged from -1.17 to ≤ 1.13. (c) Expansion of BAC map in regions that are positive for CENP-C and CENP-H in each neocentromere examined, showing BAC names and overlaps, the genes, and the previously determined CENP-A domains. For cell line BBB, the CENP-A, CENP-C, and CENP-H were mapped to the identical BACs (negative for RP11-811P12, strongly positive for BAC 46I10, and weakly positive for 29B2). For cell line IMS13q, the CENP-A mapped to two contiguous BACs (RP11-721F4 and RP11-199B17), whereas CENP-C and CENP-H mapped only to one BAC (RP11-199B17).