The damage and repair of DNA is a continuous process required to maintain genomic integrity. DNA double-strand breaks (DSBs) are the most lethal type of DNA damage and require timely repair by dedicated machinery. DSB repair is uniquely important to nondividing, post-mitotic cells of the central nervous system (CNS). These long-lived cells must rely on the intact genome for a lifetime while maintaining high metabolic activity. When these mechanisms fail, the loss of certain neuronal populations upset delicate neural networks required for higher cognition and disrupt vital motor functions. Mammalian cells engage with several different strategies to recognize and repair chromosomal DSBs based on the cellular context and cell cycle phase, including homologous recombination (HR)/homology-directed repair (HDR), microhomology-mediated end-joining (MMEJ), and the classic non-homologous end-joining (NHEJ). In addition to these repair pathways, a growing body of evidence has emphasized the importance of DNA damage response (DDR) signaling, and the involvement of heterogeneous nuclear ribonucleoprotein (hnRNP) family proteins in the repair of neuronal DSBs, many of which are linked to age-associated neurological disorders. In this review, we describe contemporary research characterizing the mechanistic roles of these non-canonical proteins in neuronal DSB repair, as well as their contributions to the etiopathogenesis of selected common neurological diseases.

Klebsiella pneumoniae is a leading cause of nosocomial infections in the United States. Due to the emergence of multidrug-resistant strains, phages targeting K. pneumoniae may be a useful alternative against this pathogen. Here, we announce the complete genome of K. pneumoniae pseudo-T-even myophage Matisse and describe its features.

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This study establishes the physiological role of Fused in Sarcoma (FUS) in mitochondrial DNA (mtDNA) repair and highlights its implications to the pathogenesis of FUS-associated neurodegenerative diseases such as Amyotrophic lateral sclerosis (ALS). Endogenous FUS interacts with and recruits mtDNA Ligase IIIα (mtLig3) to DNA damage sites within mitochondria, a relationship essential for maintaining mtDNA repair and integrity in healthy cells. Using ALS patient-derived FUS mutant cell lines, a transgenic mouse model, and human autopsy samples, we discovered that compromised FUS functionality hinders mtLig3's repair role, resulting in increased mtDNA damage and mutations. These alterations cause various manifestations of mitochondrial dysfunction, particularly under stress conditions relevant to disease pathology. Importantly, rectifying FUS mutations in patient-derived induced pluripotent cells (iPSCs) preserves mtDNA integrity. Similarly, targeted introduction of human DNA Ligase 1 restores repair mechanisms and mitochondrial activity in FUS mutant cells, suggesting a potential therapeutic approach. Our findings unveil FUS's critical role in mitochondrial health and mtDNA repair, offering valuable insights into the mechanisms underlying mitochondrial dysfunction in FUS-associated neurodegeneration.

Fused-in Sarcoma (FUS) gene mutations have been implicated in amyotrophic lateral sclerosis (ALS). This study aimed to investigate the impact of FUS mutations (R521H and P525L) on the transcriptome of induced pluripotent stem cells (iPSCs) and iPSC-derived motor neurons (iMNs). Using RNA sequencing (RNA Seq), we characterized differentially expressed genes (DEGs), differentially expressed lncRNAs (DELs), and subsequently predicted lncRNA-mRNA target pairs (TAR pairs). Our results show that FUS mutations significantly altered expression profiles of mRNAs and lncRNAs in iPSCs. We identified key differentially regulated TAR pairs, including LMO3, TMEM132D, ERMN, GPR149, CRACD, and ZNF404 in mutant FUS iPSCs. We performed reverse transcription PCR (RT-PCR) validation in iPSCs and iMNs. Validation confirmed RNA-Seq findings and suggested that mutant FUS-induced transcriptional alterations persisted from iPSCs into differentiated iMNs. Functional enrichment analyses of DEGs indicated pathways associated with neuronal development and carcinogenesis that were likely altered by FUS mutations. Ingenuity Pathway Analysis (IPA) and GO network analysis of lncRNA-targeted mRNAs indicated associations related to RNA metabolism, lncRNA regulation, and DNA damage repair. Our findings provide insights into the molecular mechanisms underlying the pathophysiology of ALS-associated FUS mutations and suggest potential therapeutic targets for the treatment of ALS.

Patients with Autosomal Dominant Polycystic Kidney disease (ADPKD) have multiple cardiovascular manifestations, including increased susceptibility to arrhythmias. Mutations in polycystin-1 (PC1) encoding gene accounts for 85% cases of ADPKD, whereas mutations in polycystin-2 (PC2) only accounts for 15%. In kidney cells, PC1 interacts with PC2 to form a protein complex at the primary cilia to regulate calcium influx via PC2. However, cardiomyocytes are non-ciliated cells and the role of both PC1 and PC2 in atrial cardiomyocytes remains unknown. We have previously demonstrated that PC1 regulates action potentials and calcium handling to fine-tune ventricular cardiomyocyte contraction. Here, we hypothesize that PC1 regulates action potentials and calcium handling in atrial cardiomyocytes independent of PC2 actions. To test this hypothesis, we differentiated human induced pluripotent stem cells (iPSC) into atrial cardiomyocytes (iPSC-aCM) using previously published protocols. To determine the contribution of PC1/PC2 in atrial excitation-contraction coupling, protein expression was knocked down utilizing specific siRNA constructs, for each protein, or a universal control siRNA transfected using lipofectamine RNAiMAX. We measured action potentials using the potentiometric dye FluoVolt and intracellular calcium with Fura-2 AM or Fluo-4. Changes in fluorescence were monitored using a multiwavelength IonOptix system. iPSC-aCM were paced at 2 Hz to synchronize the beating pattern using field electrical stimulation. Our data shows that PC1 ablation significantly decreased action potential duration at 50% and 80% of repolarization, by 24% and 23%, respectively. Moreover, we observed that PC1 knockdown significantly reduced calcium transient amplitude elicited by field electrical stimulation without changes in calcium transient decay. Interestingly, PC2 knockdown did not modify calcium transients in atrial cardiomyocytes (iPSC-aCM). Our data suggest that PC1 regulates atrial excitation-contraction coupling independent of PC2 actions. This study warrants further investigation into atrial dysfunction in ADPKD patients with PC1 mutations.