Pediatric primary lymphoma of bone in epiphysis case report.

Primary lymphoma of the bone (PLB) is a rare entity, with a majority of pediatric cases presenting in the metaphysis of long bones. There have been only seven reported cases to date of pediatric lymphoma of the bone arising from the epiphysis, of which only two have been described in the proximal tibia. We report a pediatric case of PLB in the tibial epiphysis which presented initially with knee pain. Imaging was performed with X-ray, MRI, CT, and PET-CT with bone biopsies revealing diffuse large B-cell lymphoma. This patient also showed a second, synchronous lesion in the left iliac bone, which was also biopsy proven to diffuse large B-cell lymphoma. Lymphoma in the epiphysis for children is rare and often confused with infectious etiologies or other types of tumors. Misdiagnosis may result in inappropriate treatment and possible progression of the disease, thus making early identification important to initiate therapy.

Synthetic Essentiality of Metabolic Regulator PDHK1 in PTEN-Deficient Cells and Cancers.

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a tumor suppressor and bi-functional lipid and protein phosphatase. We report that the metabolic regulator pyruvate dehydrogenase kinase1 (PDHK1) is a synthetic-essential gene in PTEN-deficient cancer and normal cells. The PTEN protein phosphatase dephosphorylates nuclear factor κB (NF-κB)-activating protein (NKAP) and limits NFκB activation to suppress expression of PDHK1, a NF-κB target gene. Loss of the PTEN protein phosphatase upregulates PDHK1 to induce aerobic glycolysis and PDHK1 cellular dependence. PTEN-deficient human tumors harbor increased PDHK1, a biomarker of decreased patient survival. This study uncovers a PTEN-regulated signaling pathway and reveals PDHK1 as a potential target in PTEN-deficient cancers.

Long-term multilineage engraftment of autologous genome-edited hematopoietic stem cells in nonhuman primates.

Genome editing in hematopoietic stem and progenitor cells (HSPCs) is a promising novel technology for the treatment of many human diseases. Here, we evaluated whether the disruption of the C-C chemokine receptor 5 (CCR5) locus in pigtailed macaque HSPCs by zinc finger nucleases (ZFNs) was feasible. We show that macaque-specific CCR5 ZFNs efficiently induce CCR5 disruption at levels of up to 64% ex vivo, 40% in vivo early posttransplant, and 3% to 5% in long-term repopulating cells over 6 months following HSPC transplant. These genome-edited HSPCs support multilineage engraftment and generate progeny capable of trafficking to secondary tissues including the gut. Using deep sequencing technology, we show that these ZFNs are highly specific for the CCR5 locus in primary cells. Further, we have adapted our clonal tracking methodology to follow individual CCR5 mutant cells over time in vivo, reinforcing that CCR5 gene-edited HSPCs are capable of long-term engraftment. Together, these data demonstrate that genome-edited HSPCs engraft, and contribute to multilineage repopulation after autologous transplantation in a clinically relevant large animal model, an important step toward the development of stem cell-based genome-editing therapies for HIV and potentially other diseases as well.

Acute knockdown of AMPA receptors reveals a trans-synaptic signal for presynaptic maturation.

Newly formed glutamatergic synapses often lack postsynaptic AMPA-type glutamate receptors (AMPARs). Aside from 'unsilencing' the postsynaptic site, however, the significance of postsynaptic AMPAR insertion during synapse maturation remains unclear. To investigate the role of AMPAR in synapse maturation, we used RNA interference (RNAi) to knockdown AMPARs in cultured hippocampal neurons. Surprisingly, loss of postsynaptic AMPARs increased the occurrence of presynaptically inactive synapses without changing the release probability of the remaining active synapses. Additionally, heterologous synapses formed between axons and AMPAR-expressing HEK cells develop significantly fewer inactive presynaptic terminals. The extracellular domain of the AMPAR subunit GluA2 was sufficient to reproduce this effect at heterologous synapses. Indeed, the retrograde signalling by AMPARs is independent of their channel function as RNAi-resistant AMPARs restore synaptic transmission in neurons lacking AMPARs despite chronic receptor antagonist treatment. Our findings suggest that postsynaptic AMPARs perform an organizational function at synapses that exceeds their standard role as ionotropic receptors by conveying a retrograde trans-synaptic signal that increases the transmission efficacy at a synapse.