Publications by authors named "John A Schmiesing"

Cohesin is an essential multiprotein complex that mediates sister chromatid cohesion critical for proper segregation of chromosomes during cell division. Cohesin is also involved in DNA double-strand break (DSB) repair. In mammalian cells, cohesin is involved in both DSB repair and the damage checkpoint response, although the relationship between these two functions is unclear.

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The β-globin locus undergoes dynamic chromatin interaction changes in differentiating erythroid cells that are thought to be important for proper globin gene expression. However, the underlying mechanisms are unclear. The CCCTC-binding factor, CTCF, binds to the insulator elements at the 5' and 3' boundaries of the locus, but these sites were shown to be dispensable for globin gene activation.

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Facioscapulohumeral dystrophy (FSHD) is an autosomal dominant muscular dystrophy in which no mutation of pathogenic gene(s) has been identified. Instead, the disease is, in most cases, genetically linked to a contraction in the number of 3.3 kb D4Z4 repeats on chromosome 4q.

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Chromosome shaping and individualization are necessary requisites to warrant the correct segregation of genomes in either mitotic or meiotic cell divisions. These processes are mainly prompted in vertebrates by three multiprotein complexes termed cohesin and condensin I and II. In the present study we have analyzed by immunostaining the appearance and subcellular distribution of condensin I in mouse mitotic and meiotic chromosomes.

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Condensins are essential protein complexes critical for mitotic chromosome organization. Little is known about the function of condensins during interphase, particularly in mammalian cells. Here we report the interphase-specific interaction between condensin I and the DNA nick-sensor poly(ADP-ribose) polymerase 1 (PARP-1).

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Proper patterns of genome-wide DNA methylation, mediated by DNA methyltransferases DNMT1, -3A and -3B, are essential for embryonic development and genomic stability in mammalian cells. The de novo DNA methyltransferase DNMT3B is of particular interest because it is frequently overexpressed in tumor cells and is mutated in immunodeficiency, centromere instability and facial anomalies (ICF) syndrome. In order to gain a better understanding of DNMT3B, in terms of the targeting of its methylation activity and its role in genome stability, we biochemically purified endogenous DNMT3B from HeLa cells.

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SMC proteins are components of cohesin complexes that function in chromosome cohesion. We determined that SMC1alpha and SMC3 localized to wild-type mouse meiotic chromosomes, but with distinct differences in their patterns. Anti-SMC3 coincided with axial elements of the synaptonemal complex, while SMC1alpha was observed mainly in regions where homologues were synapsed.

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Nucleosomal DNA is arranged in a higher-order structure that presents a barrier to most cellular processes involving protein DNA interactions. The cellular machinery involved in sister chromatid cohesion, the cohesin complex, also requires access to the nucleosomal DNA to perform its function in chromosome segregation. The machineries that provide this accessibility are termed chromatin remodelling factors.

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CNAP1 (hCAP-D2/Eg7) is an essential component of the human condensin complex required for mitotic chromosome condensation. This conserved complex contains a structural maintenance of chromosomes (SMC) family protein heterodimer and three non-SMC subunits. The mechanism underlying condensin targeting to mitotic chromosomes and the role played by the individual condensin components, particularly the non-SMC subunits, are not well understood.

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