Inhibition of SETMAR–H3K36me2–NHEJ repair axis in residual disease cells prevents glioblastoma recurrence

BackgroundResidual disease of glioblastoma (GBM) causes recurrence. However, targeting residual cells has failed, due to their inaccessibility and our lack of understanding of their survival mechanisms to radiation therapy. Here we deciphered a residual cell–specific survival mechanism essential for GBM relapse.MethodsTherapy resistant residual (RR) cells were captured from primary patient samples and cell line models mimicking clinical scenario of radiation resistance. Molecular signaling of resistance in RR cells was identified using RNA sequencing, genetic and pharmacological perturbations, overexpression systems, and molecular and biochemical assays. Findings were validated in patient samples and an orthotopic mouse model.ResultsRR cells form more aggressive tumors than the parental cells in an orthotopic mouse model. Upon radiation-induced damage, RR cells preferentially activated a nonhomologous end joining (NHEJ) repair pathway, upregulating Ku80 and Artemis while downregulating meiotic recombination 11 (Mre11) at protein but not RNA levels. Mechanistically, RR cells upregulate the Su(var)3-9/enhancer-of-zeste/trithorax (SET) domain and mariner transposase fusion gene (SETMAR), mediating high levels of H3K36me2 and global euchromatization. High H3K36me2 leads to efficiently recruiting NHEJ proteins. Conditional knockdown of SETMAR in RR cells induced irreversible senescence partly mediated by reduced H3K36me2. RR cells expressing mutant H3K36A could not retain Ku80 at double-strand breaks, thus compromising NHEJ repair, leading to apoptosis and abrogation of tumorigenicity in vitro and in vivo. Pharmacological inhibition of the NHEJ pathway phenocopied H3K36 mutation effect, confirming dependency of RR cells on the NHEJ pathway for their survival.ConclusionsWe demonstrate that the SETMAR-NHEJ regulatory axis is essential for the survival of clinically relevant radiation RR cells, abrogation of which prevents recurrence in GBM.     

NMDA Receptor Enhances Correlation of Spontaneous Activity in Neonatal Barrel Cortex

Correlated spontaneous activity plays critical role in the organization of neocortical circuits during development. However, cortical mechanisms regulating activity correlation are still elusive. In this study, using two-photon calcium imaging of the barrel cortex layer 4 (L4) in living neonatal mice, we found that NMDA receptors (NMDARs) in L4 neurons are important for enhancement of spontaneous activity correlation. Disruption of GluN1 (Grin1), an obligatory NMDAR subunit, in a sparse population of L4 neurons reduced activity correlation between GluN1 knock-out (GluN1KO) neuron pairs within a barrel. This reduction in activity correlation was even detected in L4 neuron pairs in neighboring barrels and most evident when either or both of neurons are located on the barrel edge. Our results provide evidence for the involvement of L4 neuron NMDARs in spatial organization of the spontaneous firing activity of L4 neurons in the neonatal barrel cortex.SIGNIFICANCE STATEMENT Precise wiring of the thalamocortical circuits is necessary for proper sensory information processing, and thalamus-derived correlated spontaneous activity is important for thalamocortical circuit formation. The molecular mechanisms involved in the correlated activity transfer from the thalamus to the neocortex are largely unknown. In vivo two-photon calcium imaging of the neonatal barrel cortex revealed that correlated spontaneous activity between layer four neurons is reduced by mosaic knock-out (KO) of the NMDA receptor (NMDAR) obligatory subunit GluN1. Our results suggest that the function of NMDARs in layer four neurons is necessary for the communication between presynaptic and postsynaptic partners during thalamocortical circuit formation.     

A quality improvement initiative to increase pneumococcal vaccination coverage among children after kidney transplant

Pneumococcal vaccination rates among children receiving a kidney transplant remain suboptimal. Current practice guidelines in the United States recommend giving the PPSV23 after priming with the PCV13. We conducted a QI initiative to increase pneumococcal vaccine rates in our kidney transplant recipients by developing an age‐based vaccine algorithm, obtaining vaccine records, and generating reminders for patients and clinicians. A monthly report from the EHR tracked outcomes. The process metric was missed vaccine opportunities, and the overall objective was to improve coverage with both the PCV13 and PPSV23. Over the first six months, we increased the percentage of visits where the vaccine was given from a baseline of 4% to 33%. However, by the end of the 12‐month period, the percentage of eligible visits where the vaccine was given decreased to 8.7%. Nevertheless, over the 12‐month observation period, we were able to increase the percentage of transplant patients receiving the PCV13 and PPSV23 from 6% to 52%. Utilizing an age‐based algorithm and the electronic medical record, vaccine champions can track both missed visit opportunities and the number of vaccinated patients to improve pneumococcal immunization coverage for these high‐risk patients.     

Hereditary Angioedema-Presenting as Recurrent Abdominal Pain

We report a very rare case of HEREDITARY ANGIOEDEMA, presenting as recurrent acute abdomen. A 22 yr old Maharastrian male, law college student, got admitted for about fifteen times in previous three years for severe, acute onset, upper abdominal pain, vomiting, distention and acute exudative inflammatory ascites .The whole episode used to subside spontaneously within 2–3 days with or without conservative general management .He underwent various investigations from far basic type, to advanced and invasive type with each recurrence but without definitive diagnosis. He also underwent unnecessary appendectomy. The authors did a review of his previous records, but didn't find any definite surgical or medical cause for his acute abdomen. Obviously it was something rare. Authors did search for it in various surgical and medical literature and searched extensively on internet for rare causes of abdominal pain which guided them for further appropriate investigations and diagnose him as a case of HEREDITARY ANGIOEDEMA ,as his clinical features and C1-INH,C3-C4 levels were strongly in favour of it . It goes without saying that the internet has become a standard accessory to conventional literature for cases with diagnostic dilemmas and for treatment options as well.