Cytogenetic bands reflect genomic organization in large blocks of DNA with similar properties. Because banding patterns are invariant, this organization may often be assumed unimportant for genome regulation. Results here challenge that view. Findings here suggest cytogenetic bands reflect a visible framework upon which regulated genome architecture is built. Given Alu and L1 densities differ in cytogenetic bands, we examined their distribution after X-chromosome inactivation or formation of senescent-associated heterochromatin foci (SAHFs). Alu-rich regions remain outside both SAHFs and the Barr Body (BB), affirming that the BB is not the whole chromosome but a condensed, L1-rich core. Hi-C analysis of senescent cells demonstrates large (~10 Mb) G-bands remodel as a contiguous unit, gaining distal intrachromosomal interactions as syntenic G-bands coalesce into SAHFs. Striking peaks of Alu within R-bands strongly resist condensation. Thus, large-scale segmental genome architectur relates to dark versus light cytogenetic bands and Alu-peaks, implicating both in chromatin regulation.
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機(jī)譯:細(xì)胞遺傳學(xué)條帶反映了具有相似特性的大 DNA 塊中的基因組組織。由于條帶模式是不變的,因此通常認(rèn)為這種組織對基因組調(diào)控不重要。這里的結(jié)果挑戰(zhàn)了這種觀點(diǎn)。這里的研究結(jié)果表明,細(xì)胞遺傳學(xué)條帶反映了一個(gè)可見的框架,調(diào)節(jié)基因組結(jié)構(gòu)建立在該框架之上。鑒于 Alu 和 L1 密度在細(xì)胞遺傳學(xué)條帶上不同,我們檢查了它們在 X 染色體失活或衰老相關(guān)異染色質(zhì)病灶 (SAHF) 形成后的分布。富含 Alu 的區(qū)域保留在 SAHF 和 Barr 體 (BB) 之外,證實(shí) BB 不是整個(gè)染色體,而是一個(gè)濃縮的、富含 L1 的核心。衰老細(xì)胞的 Hi-C 分析表明,大 (~10 Mb) G 帶重塑為一個(gè)連續(xù)單元,隨著同線 G 帶聚結(jié)成 SAHF 而獲得遠(yuǎn)端染色體內(nèi)相互作用。R 帶內(nèi) Alu 的醒目峰強(qiáng)烈抵抗凝聚。因此,大規(guī)模節(jié)段基因組結(jié)構(gòu)與暗與亮細(xì)胞遺傳學(xué)條帶和 Alu 峰有關(guān),都與染色質(zhì)調(diào)控有關(guān)。
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