Rescue of a severe mouse model for spinal muscular atrophy by U7 snRNA-mediated splicing modulation

In spinal muscular atrophy (SMA), the leading genetic cause of early childhood death, the survival motor neuron 1 gene (SMN1) is deleted or inactivated. The nearly identical SMN2 gene has a silent mutation that impairs the utilization of exon 7 and the production of functional protein. It has been hypothesized that therapies boosting SMN2 exon 7 inclusion might prevent or cure SMA. Exon 7 inclusion can be stimulated in cell culture by oligonucleotides or intracellularly expressed RNAs, but evidence for an in vivo improvement of SMA symptoms is lacking. Here, we unambiguously confirm the above hypothesis by showing that a bifunctional U7 snRNA that stimulates exon 7 inclusion, when introduced by germline transgenesis, can efficiently complement the most severe mouse SMA model. These results are significant for the development of a somatic SMA therapy, but may also provide new means to study pathophysiological aspects of this devastating diseas

Chromosome Conformation Capture Uncovers Potential Genome-Wide Interactions between Human Conserved Non-Coding Sequences

Comparative analyses of various mammalian genomes have identified numerous conserved non-coding (CNC) DNA elements that display striking conservation among species, suggesting that they have maintained specific functions throughout evolution. CNC function remains poorly understood, although recent studies have identified a role in gene regulation. We hypothesized that the identification of genomic loci that interact physically with CNCs would provide information on their functions. We have used circular chromosome conformation capture (4C) to characterize interactions of 10 CNCs from human chromosome 21 in K562 cells. The data provide evidence that CNCs are capable of interacting with loci that are enriched for CNCs. The number of trans interactions varies among CNCs; some show interactions with many loci, while others interact with few. Some of the tested CNCs are capable of driving the expression of a reporter gene in the mouse embryo, and associate with the oligodendrocyte genes OLIG1 and OLIG2. Our results underscore the power of chromosome conformation capture for the identification of targets of functional DNA elements and raise the possibility that CNCs exert their functions by physical association with defined genomic regions enriched in CNCs. These CNC-CNC interactions may in part explain their stringent conservation as a group of regulatory sequences

A KRAB/KAP1-miRNA Cascade Regulates Erythropoiesis Through Stage-Specific Control of Mitophagy

During hematopoiesis, lineage- and stage-specific transcription factors work in concert with chromatin modifiers to direct the differentiation of all blood cells. We explored the role of KRAB-containing zinc finger proteins (KRAB-ZFPs) and their cofactor KAP1 in this process. In mice, hematopoietic-restricted deletion of Kap1 resulted in severe hypoproliferative anemia. Kap1-deleted erythroblasts failed to induce mitophagy-associated genes and retained mitochondria. This was due to persistent expression of microRNAs (miRNAs) targeting mitophagy transcripts, itself secondary to a lack of repression by stage-specific KRAB-ZFPs. The KRAB/KAP1-miRNA regulatory cascade is evolutionarily conserved, as it also controls mitophagy during human erythropoiesis. Thus, a multilayered transcription regulatory system is present, in which protein- and RNA-based repressors are superimposed in combinatorial fashion to govern the timely triggering of an important differentiation event

Measuring In Vivo Protein Half-Life

Protein turnover critically influences many biological functions, yet methods have been lacking to assess this parameter in vivo. Here, we demonstrate how chemical labeling of SNAP-tag fusion proteins can be exploited to measure the half-life of resident intracellular and extracellular proteins in living mice. First, we demonstrate that SNAP-tag substrates have wide bioavailability in mice and can be used for the specific in vivo labeling of SNAP-tag fusion proteins. We then apply near-infrared probes to perform noninvasive imaging of in vivo-labeled tumors. Finally, we use SNAP-mediated chemical pulse-chase labeling to perform measurement of the in vivo half-life of different extra- and intracellular proteins. These results open broad perspectives for studying protein function in living animals

DUX-family transcription factors regulate zygotic genome activation in placental mammals

In animal embryos, transcription is mostly silent for several cell divisions, until the release of the first major wave of embryonic transcripts through so-called zygotic genome activation (ZGA). Maternally provided ZGA-triggering factors have been identified in Drosophila melanogaster and Danio rerio, but their mammalian homologs are still undefined. Here, we provide evidence that the DUX family of transcription factors is essential to this process in mice and potentially in humans. First, human DUX4 and mouse Dux are both expressed before ZGA in their respective species. Second, both orthologous proteins bind the promoters of ZGA-associated genes and activate their transcription. Third, Dux knockout in mouse embryonic stem cells (mESCs) prevents the cells from cycling through a 2-cell-like state. Finally, zygotic depletion of Dux leads to impaired early embryonic development and defective ZGA. We conclude that DUX-family proteins are key inducers of zygotic genome activation in placental mammals

Inguinal lymph node metastases from a testicular seminoma: a case report and a review of the literature

<p>Abstract</p> <p>Introduction</p> <p>We report the case of a true hermaphrodite with testicular seminoma with resulting metastases to the inguinal lymph nodes eight months after radical orchidectomy. This is an unusual presentation of testicular cancer and, to the best of our knowledge, the first report of this kind in the literature.</p> <p>Case presentation</p> <p>A 45-year-old Caucasian true hermaphrodite, raised as a male, developed a testicular seminoma. He had undergone a left orchidopexy at the age of 10 for undescended testes. Metastases from testicular tumors to inguinal lymph nodes are a rare occurrence. It has been suggested that previous inguinal or scrotal surgery may alter the pattern of nodal metastasis of testicular cancer. We review the literature to evaluate the incidence of inguinal lymph node involvement in early stage testicular cancer and discuss possible routes of metastases to this unusual site. We also discuss the management of the inguinal lymph nodes in patients with testicular tumors and a previous history of inguinal or scrotal surgery, as this remains controversial.</p> <p>Conclusion</p> <p>Inguinal lymph node metastases from testicular cancer are rare. A history of inguinal or scrotal surgery may predispose involvement of the inguinal nodes. During radical inguinal orchidectomy, the surgeon should be careful to minimize the handling of the testis and ensure high ligation of the spermatic cord up to the internal inguinal ring to reduce the risk of inguinal lymph node metastasis.</p

A systematic enhancer screen using lentivector transgenesis identifies conserved and non-conserved functional elements at the olig1 and olig2 locus

Finding sequences that control expression of genes is central to understanding genome function. Previous studies have used evolutionary conservation as an indicator of regulatory potential. Here, we present a method for the unbiased in vivo screen of putative enhancers in large DNA regions, using the mouse as a model. We cloned a library of 142 overlapping fragments from a 200 kb-long murine BAC in a lentiviral vector expressing LacZ from a minimal promoter, and used the resulting vectors to infect fertilized murine oocytes. LacZ staining of E11 embryos obtained by first using the vectors in pools and then testing individual candidates led to the identification of 3 enhancers, only one of which shows significant evolutionary conservation. In situ hybridization and 3C/4C experiments suggest that this enhancer, which is active in the neural tube and posterior diencephalon, influences the expression of the Olig1 and/or Olig2 genes. This work provides a new approach for the large-scale in vivo screening of transcriptional regulatory sequences, and further demonstrates that evolutionary conservation alone seems too limiting a criterion for the identification of enhancers

Evaluation of short‐term safety of ultrasound‐guided foetal fluid sampling in the dog (Canis lupus familiaris)

Background: In humans, analysis of amniotic fluid is widely used for diagnostic and prognostic purposes. Amniocentesis has scarcely been used in veterinary medicine to date, despite a tremendous potential for clinical and research applications in dogs. Our study aimed to establish a safe method for foetal fluid sampling in female dogs. Methods: Two transabdominal ultrasound-guided methods were assessed: the "free hand" and the needle-guided bracket sampling. In addition, through a subsequent routinely scheduled ovariohysterectomy, fluid was directly collected. Samples from 98 conceptuses were collected at day 46.7 +/- 7.5 of pregnancy. Results: The amount of fluid retrieved varied between 0.5 and 5.0 ml per collection. Macroscopic examination of the uterus and conceptuses identified 53% of the puncture sites. Neither fluid leakage nor foetal injury was detected, and six hematomas (5.8%) were visible. Ultrasound-guided foetal fluid collection was found to be potentially safe, and it can be performed by using either transabdominal method. Conclusion: Foetal fluid collection is possible with relative ease and low short-term risk, and may open paths for diagnostic, therapeutic and research purposes in dogs. The procedure can provide new insights into prenatal clinical medicine, including diagnostics of foetal deaths, early identification of heritable diseases and so on

A physical analysis of the Y chromosome shows no additional deletions, other than Gr/Gr, associated with testicular germ cell tumour

Testicular germ cell tumour (TGCT) is the most common malignancy in men aged 15–45 years. A small deletion on the Y chromosome known as ‘gr/gr' was shown to be associated with a two-fold increased risk of TGCT, increasing to three-fold in cases with a family history of TGCT. Additional deletions of the Y chromosome, known as AZFa, AZFb and AZFc, are described in patients with infertility; however, complete deletions of these regions have not been identified in TGCT patients. We screened the Y chromosome in a series of TGCT cases to evaluate if additional deletions of Y were implicated in TGCT susceptibility. Single copy Y chromosome STS markers with an average inter-marker spacing of 128 kb were examined in constitutional DNA of 271 index TGCT patients. Three markers showed evidence of deletions, sY1291, indicative of ‘gr/gr' (eight out of 271; 2.9%), Y-DAZ3 contained within ‘gr/gr' (21 out of 271; 7.7%) and a single deletion of the marker G66152 was identified in one TGCT case. No other markers demonstrated deletions. While several regions of the Y chromosome are known to be deleted and associated with infertility, our study provides no evidence to suggest regions of Y deletion, other than ‘gr/gr', are associated with susceptibility to TGCT in UK patients