Summary Deciphering how neuronal diversity is established and maintained requires a detailed knowledge of neuronal gene expression throughout development. In contrast to mammalian brains 1 , 2 , the large neuronal diversity of the Drosophila optic lobes 3 and its connectome 4 – 6 are almost completely characterized. However, a molecular characterization of this diversity, particularly during development, has been lacking. We present novel insights into brain development through a nearly exhaustive description of the transcriptomic diversity of the optic lobes. We acquired the transcriptome of 275,000 single-cells at adult and five pupal stages, and developed a machine learning framework to assign them to almost 200 cell-types at all timepoints. We discovered two large neuronal populations that wrap neuropils during development but die just before adulthood, as well as neuronal subtypes that partition dorsal and ventral visual circuits by differential Wnt signaling throughout development. Moreover, we showed that neurons of the same type but produced days apart synchronize their transcriptomes shortly after being produced. We also resolved during synaptogenesis neuronal subtypes that converge to indistinguishable transcriptomic profiles in adults while greatly differing in morphology and connectivity. Our datasets almost completely account for the known neuronal diversity of the optic lobes and serve as a paradigm to understand brain development across species.

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Nijmegen breakage syndrome (NBS) is a chromosomal instability syndrome associated with cancer predisposition, radiosensitivity, microcephaly, and growth retardation. The NBS gene product, NBS1 (p95) or nibrin, is a part of the hMre11 complex, a central player associated with double strand break repair. We previously demonstrated that c-Myc directly activates NBS1 expression. Here we have shown that constitutive expression of NBS1 in Rat1a and HeLa cells induces/enhances their transformation. Repression of endogenous NBS1 levels using short interference RNA reduces the transformation activity of two tumor cell lines. Increased NBS1 expression is observed in 40 -52% of non-small cell lung carcinoma, hepatoma, and esophageal cancer samples. NBS1 overexpression stimulates phosphatidylinositol (PI) 3-kinase activity, leading to increased phosphorylation levels of Akt and its downstream targets such as glycogen synthase kinase 3␤ and mammalian target of rapamycin in different cell lines and tumor samples. Transformation induced by NBS1 overexpression can be inhibited by a PI3-kinase inhibitor (LY294002). Repression of endogenous Akt expression by short interference RNA decreases the transformation activity of Rat1a cells overexpressing NBS1. These results indicate that overexpression of NBS1 is an oncogenic event that contributes to transformation through the activation of PI3-kinase/Akt. Nijmegen breakage syndrome (NBS)3 is an autosomal recessive hereditary disorder characterized by microcephaly, a "bird-like" facial appearance, growth retardation, immunodeficiency, radiosensitivity, chromosomal instability, and predisposition to tumor formation (1-3). The gene defective in NBS has been cloned, and the gene product, NBS1 (p95, nibrin), is a member of the DNA double strand break repair complex (hMre11 complex) including hMre11, hRad50, and NBS1 (1, 3). Increased radiation sensitivity and radioresistant DNA synthesis of NBS fibroblasts are similar to the cellular features of AT (ataxia-telangiectasis) cells (2, 4), demonstrated by the recent results that ATM (ataxiatelangiectasis-mutated) protein phosphorylates NBS1 (5-7), linking these two proteins in the same pathway. NBS1 is a putative tumor suppressor gene as shown by the existence of NBS patients and some mutations discovered in different tumors (1, 2). However, NBS1 is expressed in highly proliferating tissues developmentally (8) and is located at sites of DNA synthesis through interaction with E2F (9). In addition, Mre11 complex is able to prevent double strand break accumulation during chromosomal DNA synthesis to ensure cell cycle progression (10). Nbs1 knock out in mouse embryonic stem cells shows the phenotype of diminished expansion of the inner cell mass of mutant blastocysts (Nbs1 null) (11, 12). Cellular proliferation defects are shown in Nbs1 m/m mouse embryonic fibroblasts (13). Obviously, the roles of NBS1 are multiple, and some of them are still subject to intensive investigation.Phosphatidylinositol (PI) 3-kinase is a major signaling component downs...

BackgroundIn congestive heart failure the balance between cell death and cell survival in cardiomyocytes is compromised. Sirtuin 1 (Sirt1) activates cell survival machinery and has been shown to be protective against ischemia/reperfusion injury in murine heart. The role of Sirt1 in heart failure, especially in human hearts is not clear.ResultsThe expression of Sirt1 and other (associated) downstream molecules in human cardiomyocytes from patients with advanced heart failure was examined. Sirt1 was down-regulated (54.92% ± 7.80% in advanced heart failure samples compared with healthy control cardiomyocytes). The modulation of molecules involved in cardiomyocyte survival and death in advanced heart failure were also examined. The expression of Mn-superoxide dismutase and thioredoxin1, as well as an antiapoptotic molecule, Bcl-xL, were all significantly reduced in advanced heart failure cardiomyoctes (0.71 ± 0.02-fold, 0.61 ± 0.05-fold, and 0.53 ± 0.08-fold vs. control, respectively); whereas the expression of proapoptotic molecule Bax was significantly increased (1.62 ± 0.18-fold vs. control). Increased TUNEL-positive number of cardiomyocytes and oxidative stress, confirmed by 8-hydorxydeoxyguanosine staining, were associated with advanced heart failure. The AMPK-Nampt-Sirt1 axis also showed inhibition in advanced heart failure in addition to severely impaired AMPK activation. Increased p53 (acetyl form) and decreased FoxO1 translocation in the nucleus may be the mechanism of down-regulation of antioxidants and up-regulation of proapoptotic molecules due to low expression of Sirt1.ConclusionIn advanced heart failure, low Sirt1 expression, like aging change may be a significant contributing factor in the downregulation of antioxidants and upregulation of proapoptotic molecules through the p53, FoxO1, and oxidative stress pathways.

Glutathione S-transferase P1 (GSTP1) participates in detoxification of potentially genotoxic compounds that may alter the efficacy and toxicity of platinum-based chemotherapy. We analyzed the influence of I105V polymorphism of GSTP1 on clinico-pathological features and outcomes in 166 Chinese patients with metastatic colorectal carcinoma who had been treated with first-line FOLFOX-4. Combined analysis of GSTP1 I105V, ERCC1-118, and XPD-751 polymorphisms was also conducted. The results showed that, in comparison with Caucasian populations, a remarkably lower prevalence of Val105 allele variants was noted (24.7%). Patients with Val105 allele variants had a higher response to FOLFOX-4 (56.1% vs 37.6%, P = 0.04), and a longer progression-free (P < 0.01) as well as overall (P < 0.01) survival. By adjusted analysis, this polymorphism was identified as an independent prognostic factor (P = 0.01). In combined analysis, patients without any risk genotype, including GSTP1-105 Ile/Ile, ERCC1-118 C/T or T/T, and XPD-751 Lys/Gln, had significantly longer progression-free and overall survivals (P < 0.01). In addition, patients with Val105 allele variants had a higher incidence of grade 3/4 cumulative neuropathy after different cycles of treatment. These data suggest that Asian populations have a lower prevalence of I105V polymorphism in GSTP1. I105V polymorphism in GSTP1, by reducing its enzymatic activity and consequential detoxification to oxaliplatin, could be a key determinant for a better outcome, but more neurotoxicity, to FOLFOX-4 treatment. (Cancer Sci 2010; 101: 530-535) C olorectal carcinoma (CRC) is one of the leading causes of cancer-related mortality in Taiwan and its incidence has increased steadily over the past few decades. Oxaliplatin is very effective in treating metastatic CRC patients, (1,2) and improves the disease-free survival of patients with stage II ⁄ III CRC. Neuropathy is the major toxicity of oxaliplatin, and the incidence of oxaliplatin-induced severe neuropathy has varied from 12% to 18%.(3-5) Oxaliplatin-induced neuropathy includes an acute, transient peripheral nerve hyperexcitability,and a chronic, dose-related, peripheral sensory neuropathy with symptoms similar to those caused by cisplatin.(7) Development of chronic neuropathy results in severe disturbance of neurologic functions. Therefore, identification of factors predictive of neurotoxicity to oxaliplatin treatment, including genes involved in the nucleotide excision repair (NER) (8,9) and detoxification pathways, (10) is of extreme interest. Glutathione S-transferases (GST) are a multigene family of enzymes which catalyze the conjugation of glutathione to electrophilic xenobiotics to inactivate them, and thus prevent DNA damage and adduct formation.(11) At least five major classes of the GST superfamily have been identified, (10) among them, the GSTP1, GSTT1, and GSTM1 genotypes have been studies extensively for their influences in the inter-individual variations of outcome to chemotherapeutic agents. (12,13) The isoenzyme GSTP1 is ...