Chromatin modifier MTA1 regulates mitotic transition and tumorigenesis by orchestrating mitotic mRNA processing

Dysregulated alternative splicing (AS) driving carcinogenetic mitosis remains poorly understood. Here, we demonstrate that cancer metastasis-associated antigen 1 (MTA1), a well-known oncogenic chromatin modifier, broadly interacts and co-expresses with RBPs across cancers, contributing to cancerous mitosis-related AS. Using developed fCLIP-seq technology, we show that MTA1 binds abundant transcripts, preferentially at splicing-responsible motifs, influencing the abundance and AS pattern of target transcripts. MTA1 regulates the mRNA level and guides the AS of a series of mitosis regulators. MTA1 deletion abrogated the dynamic AS switches of variants for ATRX and MYBL2 at mitotic stage, which are relevant to mitosis-related tumorigenesis. MTA1 dysfunction causes defective mitotic arrest, leads to aberrant chromosome segregation, and results in chromosomal instability (CIN), eventually contributing to tumorigenesis. Currently, little is known about the RNA splicing during mitosis; here, we uncover that MTA1 binds transcripts and orchestrates dynamic splicing of mitosis regulators in tumorigenesis.

Incidental identification of maternal malignancies in two Asian women underwent noninvasive prenatal test

Noninvasive prenatal test (NIPT) has been widely used as a screening test for trisomy 13, 18 and 21 worldwide. Recently, coexistence of maternal malignancy and pregnancy has drawn increasing attention in NIPT studies. Malignancy in pregnant women potentially affected NIPT results, which may cause false positive results or failed tests. However, no such case has ever been reported in Asian population. In this study, for the first time, we reported a stage III dysgerminoma and advanced gastric cancer during pregnancy accidentally identified during NIPT tests. These two women showed aberrant chromosome aneuploidies in NIPT results and concordant pattern of genome disruption found in tumor samples. The findings in this study further validate the effect of maternal malignancy on NIPT results and strengthen the possibility of detecting malignant tumors through NIPT in the future.

Kinesin-8 effects on mitotic microtubule dynamics contribute to spindle function in fission yeast

Kinesin-8 motor proteins destabilize microtubules. Their absence during cell division is associated with disorganized mitotic chromosome movements and chromosome loss. Despite recent work studying effects of kinesin-8s on microtubule dynamics, it remains unclear whether the kinesin-8 mitotic phenotypes are consequences of their effect on microtubule dynamics, their well-established motor activity, or additional, unknown functions. To better understand the role of kinesin-8 proteins in mitosis, we studied the effects of deletion of the fission yeast kinesin-8 proteins Klp5 and Klp6 on chromosome movements and spindle length dynamics. Aberrant microtubule-driven kinetochore pushing movements and tripolar mitotic spindles occurred in cells lacking Klp5 but not Klp6. Kinesin-8–deletion strains showed large fluctuations in metaphase spindle length, suggesting a disruption of spindle length stabilization. Comparison of our results from light microscopy with a mathematical model suggests that kinesin-8–induced effects on microtubule dynamics, kinetochore attachment stability, and sliding force in the spindle can explain the aberrant chromosome movements and spindle length fluctuations seen.

Class II Analphoid Chromosome in a Child with Aberrant Chromosome 7: A Rare Cytogenetic Association

A neocentromere is a functional centromere that has arisen within a region not known to have a centromere. We present a case with a very rarely reported class II neocentromere formation in an aberrant chromosome 7. A 22-month-old male was referred because of dysmorphic features. Banding cytogenetics was performed, and a ring 7 and a supernumerary marker chromosome along with a normal chromosome 7 were found. In situ hybridization using a centromeric probe revealed 46 signals, of which 2 signals for chromosome 7 were observed, one on the normal and one on the ring chromosome. Further analysis using FISH revealed that the linear acentric fragment was part of the 7q region, which suggests that there could be a possible McClintock mechanism.

Distal Deletion of Chromosome 11q Encompassing Jacobsen Syndrome without Platelet Abnormality

Terminal 11q deletion, known as Jacobsen syndrome (JBS), is a rare genetic disorder associated with numerous dysmorphic features. We studied two cases with multiple congenital anomalies that were cytogenetically detected with deletions on 11q encompassing JBS region: 46,XX,der(11) del(11)(q24). Array comparative genomic hybridization (aCGH) analysis confirmed partial deletion of 11.8–11.9 Mb at 11q24.1q25 (case 1) and 13.9–14 Mb deletion at 11q23.3q25 together with 7.3–7.6 Mb duplication at 12q24.32q24.33 (case 2). Dysmorphism because of the partial duplication of 12q was not overtly decipherable over the Jacobsen phenotype except for a triangular facial profile. Aberrant chromosome 11 was inherited from phenotypically normal father, carrier of balanced translocation 46,XY,t(11;12)(q23.3; q24.32). In the present study, both cases had phenotypes that were milder than the ones described in literature despite having large deletion size. Most prominent features in classical JBS is thrombocytopenia, which was absent in both these cases. Therefore, detailed functional analysis of terminal 11q region is warranted to elucidate etiology of JBS and their clinical presentation.