Antibodies to complement factor H are an uncommon cause of hemolytic uremic syndrome (HUS). Information on clinical features and outcomes in children is limited. In order to explore this we studied a multicenter cohort of 138 Indian children with anti-complement factor H antibody associated HUS, constituting 56% of patients with HUS. Antibody titers were high (mean 7054 AU/ml) and correlated inversely with levels of complement C3, but not complement factor H. Homozygous deletion of the CFHR1 gene was found in 60 of 68 patients. Therapies included dialysis in 119 children, 105 receiving plasma exchanges and 26 intravenous immunoglobulin. Induction immunosuppression consisted of 87 children receiving prednisolone with or without intravenous cyclophosphamide or rituximab. Antibody titers fell significantly following plasma exchanges and increased during relapses. Adverse outcome (stage 4-5 CKD or death) was seen in 36 at 3 months and 41 by last follow up, with relapse in 14 of 122 available children. Significant independent risk factors for adverse outcome were an antibody titer over 8000 AU/ml, low C3 and delay in plasma exchange. Combined plasma exchanges and induction immunosuppression resulted in significantly improved renal survival: one adverse outcome prevented for every 2.6 patients treated. Maintenance immunosuppressive therapy, of prednisolone with either mycophenolate mofetil or azathioprine, significantly reduced the risk of relapses. Thus, prompt use of immunosuppressive agents and plasma exchanges are useful for improving outcomes in pediatric patients with anti-complement factor H-associated HUS.

Androgen receptor (AR) mediates the growth of prostate cancer (PCa) throughout its course of development, including in abnormal splice variants (AR-SV)-driven advanced stage castration-resistant disease. AR stabilization by androgens makes it distinct from other steroid receptors, which are typically ubiquitinated and degraded by proteasomes after ligand binding. Thus, targeting AR in advanced PCa requires the development of agents that can sustainably degrade variant isoforms for effective therapy. Here we report the discovery and characterization of potent selective AR degraders (SARDs) that markedly reduce the activity of wildtype and splice variant isoforms of AR at sub-micromolar doses. Three SARDs (UT-69, UT-155, and (R)-UT-155) bind the amino-terminal transcriptional activation domain AF-1, which has not been targeted for degradation previously, with two of these SARD (UT-69 and UT-155) also binding the carboxy-terminal ligand binding domain. Despite different mechanisms of action, all three SARDs degraded wild-type AR and inhibited AR function, exhibiting greater inhibitory potency than the approved AR antagonists. Collectively, our results introduce a new candidate class of next-generation therapeutics to manage advanced PCa.

BCL-2 proteins regulate mitochondrial poration in apoptosis initiation. How the pore-forming BCL-2 Effector BAK is activated remains incompletely understood mechanistically. Here we investigate autoactivation and direct activation by BH3-only proteins, which cooperate to lower BAK threshold in membrane poration and apoptosis initiation. We define in trans BAK autoactivation as the asymmetric “BH3-in-groove” triggering of dormant BAK by active BAK. BAK autoactivation is mechanistically similar to direct activation. The structure of autoactivated BAK BH3-BAK complex reveals the conformational changes leading to helix α1 destabilization, which is a hallmark of BAK activation. Helix α1 is destabilized and restabilized in structures of BAK engaged by rationally designed, high-affinity activating and inactivating BID-like BH3 ligands, respectively. Altogether our data support the long-standing hit-and-run mechanism of BAK activation by transient binding of BH3-only proteins, demonstrating that BH3-induced structural changes are more important in BAK activation than BH3 ligand affinity.

Studies of macroH2A histone variants indicate that they have a role in regulating gene expression. To identify direct targets of the macroH2A1 variants, we produced a genome-wide map of the distribution of macroH2A1 nucleosomes in mouse liver chromatin using high-throughput DNA sequencing. Although macroH2A1 nucleosomes are widely distributed across the genome, their local concentration varies over a range of 100-fold or more. The transcribed regions of most active genes are depleted of macroH2A1, often in sharply localized domains that show depletion of 4-fold or more relative to bulk mouse liver chromatin. We used macroH2A1 enrichment to help identify genes that appear to be directly regulated by macroH2A1 in mouse liver. These genes functionally cluster in the area of lipid metabolism. All but one of these genes has increased expression in macroH2A1 knockout mice, indicating that macroH2A1 functions primarily as a repressor in adult liver. This repressor activity is further supported by the substantial and relatively uniform macroH2A1 enrichment along the inactive X chromosome, which averages 4-fold. Genes that escape X inactivation stand out as domains of macroH2A1 depletion. The rarity of such genes indicates that few genes escape X inactivation in mouse liver, in contrast to what has been observed in human cells.Nucleosomes, as basic structural units of chromatin, are important targets for modifying chromatin structure and function. One source of nucleosomal functional diversity is the substitution of histone variants for conventional histones. The macroH2A core histone variants appear to be present in most or all vertebrates and some deuterostome invertebrates, such as sea urchins. Three macroH2A variants have been identified in mammals. The macroH2A1 variants, macroH2A1.1 and macroH2A1.2, are produced by alternate splicing, and macroH2A2 is produced by a separate gene (8,13,31,34). They all have a full-length histone H2A domain on their N terminus and a C-terminal nonhistone region that primarily consists of a conserved domain called a macrodomain. Macrodomains are found as stand-alone proteins in bacteria and are embedded in other eukaryotic proteins and in proteins involved in the replication of some RNA viruses (2, 32). Some macrodomains bind ADP-ribose and related molecules (26), and a recent study indicates that ADP-ribose binding by macroH2A1.1 can alter chromatin structure (36).We estimated that there is approximately 1 macroH2A for every 30 nucleosomes in rat liver, an organ with relatively high macroH2A1 content and very little macroH2A2 (13, 31). Fluorescence studies showed that these nucleosomes are not uniformly distributed across the chromatin. Notably, macroH2A1 is preferentially localized to the inactive X chromosome (8,13,14), to centromeric chromatin in some cell types (15,22), and to transcriptionally silent senescence-associated heterochromatic foci (39), which suggests a role in repression of gene expression. macroH2A1 knockout mice are viable and fertile and show no obvious pathology...