Neuroblastoma and other pediatric tumors show a paucity of gene mutations, which has sparked an interest in their epigenetic regulation. Several tumor types include phenotypically divergent cells, resembling cells from different lineage development stages. It has been proposed that super-enhancer-associated transcription factor (TF) networks underlie lineage identity, but the role of these enhancers in intratumoral heterogeneity is unknown. Here we show that most neuroblastomas include two types of tumor cells with divergent gene expression profiles. Undifferentiated mesenchymal cells and committed adrenergic cells can interconvert and resemble cells from different lineage differentiation stages. ChIP-seq analysis of isogenic pairs of mesenchymal and adrenergic cells identified a distinct super-enhancer landscape and super-enhancer-associated TF network for each cell type. Expression of the mesenchymal TF PRRX1 could reprogram the super-enhancer and mRNA landscapes of adrenergic cells toward a mesenchymal state. Mesenchymal cells were more chemoresistant in vitro and were enriched in post-therapy and relapse tumors. Two super-enhancer-associated TF networks, which probably mediate lineage control in normal development, thus dominate epigenetic control of neuroblastoma and shape intratumoral heterogeneity.

Amyotrophic lateral sclerosis (ALS) is a devastating neurological disease with no effective treatment. Here we report the results of a moderate-scale sequencing study aimed at identifying new genes contributing to predisposition for ALS. We performed whole exome sequencing of 2,874 ALS patients and compared them to 6,405 controls. Several known ALS genes were found to be associated, and the non-canonical IκB kinase family TANK-Binding Kinase 1 (TBK1) was identified as an ALS gene. TBK1 is known to bind to and phosphorylate a number of proteins involved in innate immunity and autophagy, including optineurin (OPTN) and p62 (SQSTM1/sequestosome), both of which have also been implicated in ALS. These observations reveal a key role of the autophagic pathway in ALS and suggest specific targets for therapeutic intervention.

The chromosomal position of human genes is rapidly being established. We integrated these mapping data with genome-wide messenger RNA expression profiles as provided by SAGE (serial analysis of gene expression). Over 2.45 million SAGE transcript tags, including 160,000 tags of neuroblastomas, are presently known for 12 tissue types. We developed algorithms to assign these tags to UniGene clusters and their chromosomal position. The resulting Human Transcriptome Map generates gene expression profiles for any chromosomal region in 12 normal and pathologic tissue types. The map reveals a clustering of highly expressed genes to specific chromosomal regions. It provides a tool to search for genes that are overexpressed or silenced in cancer.

The human multidrug-resistance protein (MRP) gene family contains at least six members: MRP1, encoding the multidrug-resistance protein; MRP2 or cMOAT, encoding the canalicular multispecific organic anion transporter; and four homologs, called MRP3, MRP4, MRP5, and MRP6. In this report, we characterize MRP3, the closest homolog of MRP1. Cell lines were retrovirally transduced with MRP3 cDNA, and new monoclonal antibodies specific for MRP3 were generated. We show that MRP3 is an organic anion and multidrug transporter, like the GS-X pumps MRP1 and MRP2. In Two members of the large family of ABC transporters are known thus far to confer multidrug resistance in human cancer cells. These are the MDR1 P-glycoprotein (1) and the multidrugresistance protein MRP1 (2). Both membrane proteins transport a wide range of drugs with different cellular targets and confer resistance by decreasing the intracellular concentration of drugs. P-glycoprotein transports these drugs in unmodified form, whereas MRP1 can transport drugs either conjugated to anionic ligands such as glutathione (GSH), glucuronide, or sulfate, or in an unmodified form, possibly together with GSH. Well known substrates for MRP1 are, for example, cysteinyl leukotrienes, glutathione disulfide, S-(2,4-dinitrophenyl-)glutathione, ethacrynic acid S-glutathione, etoposide glucuronide, certain steroid glucuronides, and bile salt derivatives (3-6). Transporters with the characteristics of MRP1 are known as GS-X pumps (7) or multispecific organic anion transporters (8).Another GS-X pump is MRP2, a homolog of MRP1. Unlike MRP1, which is nearly ubiquitously expressed (9), MRP2 is present mainly in the canalicular membrane of hepatocytes (10), but is also present in other apical domains of polarized cells such as the epithelial cells of the proximal tubules of the kidney (11). Studies with mutant rats (TR Ϫ ͞GY or EHBR), which lack the MRP2 protein in the canalicular membrane of hepatocytes, have shown that the substrate specificity of MRP2 is very similar to that of MRP1 (12, 13). MRP2 also contributes to transport of anticancer drugs and some metals. The mutant rats showed a reduced biliary clearance of methotrexate (14), of the topoisomerase I inhibitor CPT-11 and its metabolites (15), and of mercury, cadmium, and arsenite (refs. 16 and 17; R.O.E., unpublished observation). Cells transduced with an MRP2 cDNA construct transport the cytostatic drug vinblastine (18). Moreover, overexpression of the MRP2 gene has been found in several cisplatinresistant cell lines (19,20), and transfection of an MRP2-antisense construct into liver cells was reported to confer an increased sensitivity to cytotoxic drugs (21). All these observations strongly suggest that MRP2 may confer multidrug resistance, but whether it does so in cancer patients remains to be established.Besides MRP1 and MRP2, there are at least four MRP homologs expressed in humans, called MRP3, MRP4, MRP5, and MRP6 (20,22). Not much is known about the substrate specificity of these putative new transporters...

Pseudoxanthoma elasticum (PXE) is a heritable disorder of the connective tissue. PXE patients frequently experience visual field loss and skin lesions, and occasionally cardiovascular complications. Histopathological findings reveal calcification of the elastic fibres and abnormalities of the collagen fibrils. Most PXE patients are sporadic, but autosomal recessive and dominant inheritance are also observed. We previously localized the PXE gene to chromosome 16p13.1 (refs 8,9) and constructed a physical map. Here we describe homozygosity mapping in five PXE families and the detection of deletions or mutations in ABCC6 (formerly MRP6) associated with all genetic forms of PXE in seven patients or families.

The multidrug-resistance associated protein MRP is a 180-to 195-kDa membrane protein associated with resistance of human tumor cells to cytotoxic drugs. We have investigated how MRP confers drug resistance in SW-1573 human lung carcinoma cells by generating a subline stably transfected with an expression vector containing MRP cDNA. MRP-overexpressing SW-1573 cells are resistant to doxorubicin, daunorubicin, vincristine, VP-16, colchicine, and rhodamine 123, but not to 4'-(9-acridinylamino)methanesulfon-manisidide or taxol. The intracellular accumulation of drug (daunorubicin, vincristine, (20) and pRc/RSV (Invitrogen). All cDNA fragments used for the assembly of the MRP cDNA were sequenced and the integrity of the MRP cDNA fragment in the resulting expression vectors, pJ3fl-MRP and pRc/RSV-MRP (Fig. 1) Abbreviations: MDR, multidrug resistance (resistant); Pgp, P-glycoprotein; SCLC, small-cell lung cancer; pH;, intracellular pH; m-AMSA, 4'-(9-acridinylamino)methanesulfon-m-anisidide. 8822The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

Schwann cells degrade myelin after injury by a novel form of selective autophagy, myelinophagy, which is positively regulated by the JNK/c-Jun pathway and is defective in the injured central nervous system.

To identify novel genes associated with ALS, we undertook two lines of investigation. We carried out a genome-wide association study comparing 20,806 ALS cases and 59,804 controls. Independently, we performed a rare variant burden analysis comparing 1,138 index familial ALS cases and 19,494 controls. Through both approaches, we identified kinesin family member 5A (KIF5A) as a novel gene associated with ALS. Interestingly, mutations predominantly in the N-terminal motor domain of KIF5A are causative for two neurodegenerative diseases: hereditary spastic paraplegia (SPG10) and Charcot-Marie-Tooth type 2 (CMT2). In contrast, ALS-associated mutations are primarily located at the C-terminal cargo-binding tail domain and patients harboring loss-of-function mutations displayed an extended survival relative to typical ALS cases. Taken together, these results broaden the phenotype spectrum resulting from mutations in KIF5A and strengthen the role of cytoskeletal defects in the pathogenesis of ALS.