Markedly Increased High-Mobility Group Box 1 Protein in a Patient with Small-for-Size Syndrome

Background. Small-for-size syndrome (SFSS) occurs in the presence of insufficient liver mass to maintain normal function after liver transplantation. Murine mortality following 85% hepatectomy can be reduced by the use of soluble receptor for advanced glycation end products (sRAGE) to scavenge damage-associated molecular patterns and prevent their engagement with membrane-bound RAGE. Aims. To explore serum levels of sRAGE, high-mobility group box-1 (HMGB1) protein, and other soluble inflammatory mediators in a fatal case of SFSS. Methods. Serum levels of HMGB1, sRAGE, IL-18, and other inflammatory mediators were measured by ELISA in a case of SFSS, and the results were compared with 8 patients with paracetamol-induced acute liver failure (ALF) and 6 healthy controls (HC). Results. HMGB1 levels were markedly higher in the SFSS patient (92.1 ng/mL) compared with the ALF patients (median (IQR) 11.4 (3.7–14.8) ng/mL) and HC (1.42 (1.38–1.56) ng/mL). In contrast, sRAGE levels were lower in the SFSS patient (1.88 ng/mL) compared with the ALF patients (3.53 (2.66–12.37) ng/mL) and were similar to HC levels (1.40 (1.23–1.89) ng/mL). Conclusion. These results suggest an imbalance between pro- and anti-inflammatory innate immune pathways in SFSS. Modulation of the HMGB1-RAGE axis may represent a future therapeutic avenue in this condition

The effect of Ku on telomere replication time is mediated by telomere length but is independent of histone tail acetylation

Peer reviewedPublisher PD

Identification of a novel toxicophore in anti-cancer chemotherapeutics that targets mitochondrial respiratory complex I

Disruption of mitochondrial function selectively targets tumour cells that are dependent on oxidative phosphorylation. However, due to their high energy demands, cardiac cells are disproportionately targeted by mitochondrial toxins resulting in a loss of cardiac function. An analysis of the effects of mubritinib on cardiac cells showed that this drug did not inhibit HER2 as reported, but directly inhibits mitochondrial respiratory complex I, reducing cardiac-cell beat rate, with prolonged exposure resulting in cell death. We used a library of chemical variants of mubritinib and showed that modifying the 1H-1,2,3-triazole altered complex I inhibition, identifying the heterocyclic 1,3-nitrogen motif as the toxicophore. The same toxicophore is present in a second anti-cancer therapeutic carboxyamidotriazole (CAI) and we demonstrate that CAI also functions through complex I inhibition, mediated by the toxicophore. Complex I inhibition is directly linked to anti-cancer cell activity, with toxicophore modification ablating the desired effects of these compounds on cancer cell proliferation and apoptosis

Subtelomeric factors antagonize telomere anchoring and Tel1-independent telomere length regulation

Yeast telomeres are anchored at the nuclear envelope (NE) through redundant pathways that require the telomere-binding factors yKu and Sir4. Significant variation is observed in the efficiency with which different telomeres are anchored, however, suggesting that other forces influence this interaction. Here, we show that subtelomeric elements and the insulator factors that bind them antagonize the association of telomeres with the NE. This is detectable when the redundancy in anchoring pathways is compromised. Remarkably, these same conditions lead to a reduction in steady-state telomere length in the absence of the ATM-kinase homologue Tel1. Both the delocalization of telomeres and reduction in telomere length can be induced by targeting of Tbf1 or Reb1, or the viral transactivator VP16, to a site 23 kb away from the TG repeat. This correlation suggests that telomere anchoring and a Tel1-independent pathway of telomere length regulation are linked, lending a functional significance to the association of yeast telomeres with the NE

Subtelomeric proteins negatively regulate telomere elongation in budding yeast

The Tbf1 and Reb1 proteins are present in yeast subtelomeric regions. We establish in this work that they inhibit telomerase-dependent lengthening of telomere. For example, tethering the N-terminal domain of Tbf1 and Reb1 in a subtelomeric region shortens that telomere proportionally to the number of domains bound. We further identified a 90 amino-acid long sequence within the N-terminal domain of Tbf1 that is necessary but not sufficient for its length regulation properties. The role of the subtelomeric factors in telomere length regulation is antagonized by TEL1 and does not correlate with a global telomere derepression. We show that the absence of TEL1 induces an alteration in the structure of telomeric chromatin, as defined biochemically by an increased susceptibility to nucleases and a greater heterogeneity of products. We propose that the absence of TEL1 modifies the organization of the telomeres, which allows Tbf1 and Reb1 to cis-inhibit telomerase. The involvement of subtelomeric factors in telomere length regulation provides a possible mechanism for the chromosome-specific length setting observed at yeast and human telomeres