No abstract

PICH (Plk1-interacting checkpoint helicase) was recently identified as an essential component of the spindle assembly checkpoint and shown to localize to kinetochores, inner centromeres, and thin threads connecting separating chromosomes even during anaphase. In this paper, we have used immuno-fiber fluorescence in situ hybridization and chromatin-immunoprecipitation to demonstrate that PICH associates with centromeric chromatin during anaphase. Furthermore, by careful analysis of PICH-positive anaphase threads through FISH as well as bromo-deoxyurdine and CREST labeling, we strengthen the evidence that these threads comprise mainly alphoid centromere deoxyribonucleic acid. Finally, by timing the addition of ICRF-193 (a specific inhibitor of topoisomerase-II alpha) to cells synchronized in anaphase, we demonstrate that topoisomerase activity is required specifically to resolve PICH-positive threads during anaphase (as opposed to being required to prevent the formation of such threads during earlier cell cycle stages). These data indicate that PICH associates with centromeres during anaphase and that most PICH-positive threads evolve from inner centromeres as these stretch in response to tension. Moreover, they show that topoisomerase activity is required during anaphase for the resolution of PICH-positive threads, implying that the complete separation of sister chromatids occurs later than previously assumed.

We have identified a large multigenerational Austrian family displaying a novel form of X-linked recessive myopathy. Affected individuals develop an adult-onset scapulo-axio-peroneal myopathy with bent-spine syndrome characterized by specific atrophy of postural muscles along with pseudoathleticism or hypertrophy and cardiac involvement. Known X-linked myopathies were excluded by simple-tandem-repeat polymorphism (STRP) and single-nucleotide polymorphism (SNP) analysis, direct gene sequencing, and immunohistochemical analysis. STRP analysis revealed significant linkage at Xq25-q27.1. Haplotype analysis based on SNP microarray data from selected family members confirmed this linkage region on the distal arm of the X chromosome, thereby narrowing down the critical interval to 12 Mb. Sequencing of functional candidate genes led to the identification of a missense mutation within the four and a half LIM domain 1 gene (FHL1), which putatively disrupts the fourth LIM domain of the protein. Mutation screening of FHL1 in a myopathy family from the UK exhibiting an almost identical phenotype revealed a 3 bp insertion mutation within the second LIM domain. FHL1 on Xq26.3 is highly expressed in skeletal and cardiac muscles. Western-blot analysis of muscle biopsies showed a marked decrease in protein expression of FHL1 in patients, in concordance with the genetic data. In summary, we have to our knowledge characterized a new disorder, X-linked myopathy with postural muscle atrophy (XMPMA), and identified FHL1 as the causative gene. This is the first FHL protein to be identified in conjunction with a human genetic disorder and further supports the role of FHL proteins in the development and maintenance of muscle tissue. Mutation screening of FHL1 should be considered for patients with uncharacterized myopathies and cardiomyopathies.

Autism or autism spectrum disorder (ASD) is a range of neurodevelopmental disorders starting in early childhood and is characterized by impairments in communication and reciprocal social interaction and presence of restricted and repetitive patterns of behavior. The contribution of genetic factors to autism is clear in twin and family studies. It is apparent that, overall, ASD is a complex non-Mendelian disorder. Recent studies suggest that copy number variations (CNVs) play a significant role in the etiology of ASD. For the current work, we recruited 245 family members from 73 ASD families from Styria, Austria. The DNA from probands was genotyped with Affymetrix single nucleotide polymorphism (SNP) 6.0 microarrays to screen for CNVs in their genomes. Analysis of the microarray data was performed using three different algorithms, and a list of stringent calls was compared to existing CNV data from over 2,357 controls of European ancestry. For stringent calls not present in controls, quantitative real-time PCR (qRT-PCR) was used to validate the CNVs in the probands and in their family members. Twenty-two CNVs were validated from this set (five of which are apparently de novo), many of which appear likely to disrupt genes that may be considered as good candidates for neuropsychiatric disorders, including DLG2, S100B, ARX, DIP2A, HPCAL1, and GPHN. Several others disrupt genes that have previously been implicated in autism, such as BDNF, AUTS2, DPP6, and C18orf22, and our data add to the growing evidence of their involvement in ASD.

Approximately one in five BRCA1 mutated breast cancers negative for ER and PR express androgen receptors. Modulation of AR might open a new avenue for treating these high-risk cancers.