Frequent tRNA gene translocation towards the boundaries with control regions contributes to the highly dynamic mitochondrial genome organization of the parasitic lice of mammals

Background The typical single-chromosome mitochondrial (mt) genome of animals has fragmented into multiple minichromosomes in the lineage Mitodivisia, which contains most of the parasitic lice of eutherian mammals. These parasitic lice differ from each other even among congeneric species in mt karyotype, i.e. the number of minichromosomes, and the gene content and gene order in each minichromosome, which is in stark contrast to the extremely conserved single-chromosome mt genomes across most animal lineages. How fragmented mt genomes evolved is still poorly understood. We use Polyplax sucking lice as a model to investigate how tRNA gene translocation shapes the dynamic mt karyotypes. Results We sequenced the full mt genome of the Asian grey shrew louse, Polyplax reclinata. We then inferred the ancestral mt karyotype for Polyplax lice and compared it with the mt karyotypes of the three Polyplax species sequenced to date. We found that tRNA genes were entirely responsible for mt karyotype variation among these three species of Polyplax lice. Furthermore, tRNA gene translocation observed in Polyplax lice was only between different types of minichromosomes and towards the boundaries with the control region. A similar pattern of tRNA gene translocation can also been seen in other sucking lice with fragmented mt genomes. Conclusions We conclude that inter-minichromosomal tRNA gene translocation orientated towards the boundaries with the control region is a major contributing factor to the highly dynamic mitochondrial genome organization in the parasitic lice of mammals.

The Role of USP6 Gene Rearrangement by FISH Analysis in Nodular Fasciitis and Histological Mimics

Background: Nodular fasciitis (NF) is a common benign fibroblast and myofibroblast tumor. Although there have been constant concerns about its histological features and differential diagnosis, NF is still the most easily misdiagnosed mesenchymal lesions, especially over diagnosed as a sarcoma. USP6 gene rearrangement was reported recently to be a reproducible and specific gene change in NF, which strongly assists the diagnosis of NF. We aim to study USP6 Gene Rearrangement in NF and other spindle cell lesions mimicking NF, and to investigate the use of USP6 Gene Rearrangement in differentiating NF and its mimics.Methods: USP6 translocation by fluorescence in situ hybridization (FISH) was studied on 40 cases of NF and 54 cases of other spindle cell lesions (including 10 cases of spindle cell sarcoma) that mimic NF. Results: Thirty-four cases (85.5%) of NF showed USP6 gene translocation, including 10 cases which previously diagnosed or considered as malignant diseases by the referring pathologists. All of other 54 cases of spindle cell lesions were negative for USP6 translocation.Conclusions: USP6 gene rearrangement by FISH analysis is a reliable test for diagnosis of NF, and also a helpful adjunct to prevent over diagnosis of NF. Positive USP6 gene rearrangement by FISH could be a useful marker to exclude malignant lesions that mimics NF.

Effects of arsenic on the topology and solubility of promyelocytic leukemia (PML)-nuclear bodies

Promyelocytic leukemia (PML) proteins are involved in the pathogenesis of acute promyelocytic leukemia (APL). Trivalent arsenic (As3+) is known to cure APL by binding to cysteine residues of PML and enhance the degradation of PML-retinoic acid receptor α (RARα), a t(15;17) gene translocation product in APL cells, and restore PML-nuclear bodies (NBs). The size, number, and shape of PML-NBs vary among cell types and during cell division. However, topological changes of PML-NBs in As3+-exposed cells have not been well-documented. We report that As3+-induced solubility shift underlies rapid SUMOylation of PML and late aggregation of PML-NBs. Most PML-NBs were toroidal and irregular-shaped in GFPPML-transduced CHO-K1 and HEK293 cells, respectively. The annular PML-NBs appeared unstable and dissipated into small PML-NBs in HEK cells. Exposure to As3+ and antimony (Sb3+) greatly reduced the solubility of PML and enhanced SUMOylation within 2 h, and prolonged exposure resulted in PML-NB agglomeration. Exposure to bismuth (Bi3+), another Group 15 element, did not induce any of these changes. ML792, a SUMO activation inhibitor, reduced the number of PML-NBs and increased the size of the NBs, but had little effect on the As3+-induced solubility change of PML. The results show that SUMOylation regulates the dynamics of PML-NBs but does not contribute to the As3+-induced solubility change of PML.

Prevalence of FOXO1 gene abnormalities in a group of round-cell rhabdomyosarcomas with alveolar morphology

Rhabdomyosarcomas (RMS) are group of soft tissue malignant tumours predominantly childhood. Alveolar rhabdomyosarcoma (aRMS) is the second most common variant of RMS. The majority of aRMSs display a translocations of FOXO1 gene. Such tumours are aggressive, metastasize early and are associated with a worse prognosis for the patient. However, some aRMS cases are rhabdomyosarcomas without classic chromosomal rearrangements. These tumors also have alveolar morphology, but neoplastic cells lack the FOXO1 gene translocation. Such fusion-negative round-cell RMSs behave clinically differently and have a better prognosis. The aim of the present study was to assess the prevalence of FOXO1 gene rearrangements in the group of round cell rhabdomyosarcomas with alveolar morphology. This study is supported by the Independent Ethics Committee and approved by the Academic Council of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology. The study group consisted of 250 formalin-fixed paraffin-embedded samples from patients with RMS. The cytogenetic study was performed by fluorescence in situ hybridization with a locus-specific identifier (LSI) for FOXO1 (13q14). The PAX3-FOXO1 (COSF247) and PAX7-FOXO1 (COSF287) fusion transcripts was detected by RT-PCR. In the study group 1 (аRMS), the rearrangement of PAX3/7-FOXO1 was detected in 44% of cases, in 32% of cases was detected a combined rearrangement with amplification of the 3' FOXO1. In one case, the amplification of the 3' end of the FOXO1 gene was detected without rearrangement; this sample was sent for additional PCR study, as a result of which the chimeric PAX3-FOXO1 transcript was detected. In 22% cases cytogenetic abnormalities were not found. has not been identified. In group 2 (embryonal RMS) we did not detect translocation. The group of round-cell PMCs is heterogeneous and is represented by three variants of genetic events that determine the disease prognosis. At the same time, FOXO1 gene abnormalities are not found in the RMS group with non-alveolar morphology.

Apply Molecular Method To Diagnosis A Very Rare Bone Primary Myoepithelial Tumor: A Case Report

Introduction/Objective A 38-year-old female without a history of trauma and malignancy presented with left knee pain and swelling for two weeks. MRI and PET scan find a left knee mass arising from the bone along the medial metaphysis of the distal femur. She underwent femur resection, and the specimen was sent for pathology evaluation. Methods Grossly, the cut surface of the sample revealed a 4.5 x 2 cm area of hemorrhagic softening of the bone with adjacent soft tissue nodules. Microscopically, the tumor showed biphasic or multiphase morphologic features, prominently presented with areas showing well-differentiated epithelial features and other areas with spindling and sheets of tumor cells. Areas suspicious for a vascular invasion were seen at the periphery of the soft tissue extension of the tumor. Immunohistochemistry stains showed the tumor cells are positive for vimentin, AE1/3, EMA, CK7, CK19, GATA3, and BRST2; and are negative for S100, HMB45, GFAP, Calponin, CDX2, PAX8, WT1, P63, CD34, and ER. The molecular test showed positive for the ESWR1 gene but negative for SYT gene translocation. Results A diagnosis of primary myoepithelial carcinoma of bone extension into surrounding soft tissue was made. Conclusion The most challenging differential diagnosis for this case is metastatic breast cancer. Many of the positive epithelial stains distinctly highlight the epithelial featured geographic areas sparing the background spindled stroma. The positive staining of GATA3 and BRST2, two commonly used breast linage markers, is unusual and not known in myoepithelial carcinoma. In light of the EWSR1 positive and SYT FISH negative results, combined with the morphologic features, locations as well as negative PET scan against its breast origins. Although many myoepithelial markers, such as S100, Calponin, P63, and GFAP were negative, make this case very unique. The molecular diagnosis is the mainstay for this final diagnosis.