N-Cadherin Orchestrates Self-Organization of Neurons within a Columnar Unit in the Drosophila Medulla.

Columnar structure is a basic unit of the brain, but the mechanism underlying its development remains largely unknown. The medulla, the largest ganglion of the Drosophila melanogaster visual center, provides a unique opportunity to reveal the mechanisms of 3D organization of the columns. In this study, using N-cadherin (Ncad) as a marker, we reveal the donut-like columnar structures along the 2D layer in the larval medulla that evolves to form three distinct layers in pupal development. Column formation is initiated by three core neurons, R8, R7, and Mi1, which establish distinct concentric domains within a column. We demonstrate that Ncad-dependent relative adhesiveness of the core columnar neurons regulates their relative location within a column along a 2D layer in the larval medulla according to the differential adhesion hypothesis. We also propose the presence of mutual interactions among the three layers during formation of the 3D structures of the medulla columns.SIGNIFICANCE STATEMENT The columnar structure is a basic unit of the brain, but its developmental mechanism remains unknown. The medulla, the largest ganglion of the fly visual center, provides a unique opportunity to reveal the mechanisms of 3D organization of the columns. We reveal that column formation is initiated by three core neurons that establish distinct concentric domains within a column. We demonstrate the in vivo evidence of N-cadherin-dependent differential adhesion among the core columnar neurons within a column along a 2D layer in the larval medulla. The 2D larval columns evolve to form three distinct layers in the pupal medulla. We propose the presence of mutual interactions among the three layers during formation of the 3D structures of the medulla columns.

Cell surface molecule, Klingon, mediates the refinement of synaptic specificity in the Drosophila visual system.

In the Drosophila brain, neurons form genetically specified synaptic connections with defined neuronal targets. It is proposed that each central nervous system neuron expresses specific cell surface proteins, which act as identification tags. Through an RNAi screen of cell surface molecules in the Drosophila visual system, we found that the cell adhesion molecule Klingon (Klg) plays an important role in repressing the ectopic formation of extended axons, preventing the formation of excessive synapses. Cell-specific manipulation of klg showed that Klg is required in both photoreceptors and the glia, suggesting that the balanced homophilic interaction between photoreceptor axons and the glia is required for normal synapse formation. Previous studies suggested that Klg binds to cDIP and our genetic analyses indicate that cDIP is required in glia for ectopic synaptic repression. These data suggest that Klg play a critical role together with cDIP in refining synaptic specificity and preventing unnecessary connections in the brain.

Real-world data of atezolizumab plus carboplatin and etoposide in elderly patients with extensive-disease small-cell lung cancer.

PURPOSE: The aim of this study was to assess the effectiveness and tolerability of atezolizumab plus carboplatin and etoposide combination chemotherapy in elderly patients with extensive-disease (ED) small-cell lung cancer (SCLC). METHODS: This retrospective study evaluated 65 SCLC patients who received atezolizumab, carboplatin, and etoposide for ED-SCLC in nine study institutions between August 2019 and September 2020. Clinical efficacy, assessed according to response rate and survival, and toxicity were compared between the elderly (n = 36 patients; median age: 74 years [range: 70-89 years]) and the non-elderly group (n = 29 patients; median age: 67 years [range: 43-69 years]). RESULTS: The response rate was 73.8% (80.5% in the elderly group and 65.5% in the non-elderly group). There was no significant difference in both the median progression-free survival (5.5 months vs. 4.9 months, p = 0.18) and the median overall survival (15.4 months vs. 15.9 months, p = 0.24) between the elderly group and the non-elderly group. The frequencies of grade ≥3 hematological adverse events in the elderly patients were as follows: decreased white blood cells, 36.1%; decreased neutrophil count, 61.1%; decreased platelet count, 8.3%; and febrile neutropenia, 8.3%. One treatment-related death due to lung infection occurred in the elderly group. CONCLUSION: Despite hematologic toxicities, especially decreased neutrophil count, atezolizumab, carboplatin, and etoposide combination chemotherapy demonstrates favorable effectiveness and acceptable toxicity in elderly patients. Thus, atezolizumab plus carboplatin and etoposide could be the preferred standard treatment modality for elderly patients with ED-SCLC.

Establishment of serum-free adapted Chinese hamster ovary cells with double knockout of GDP-mannose-4,6-dehydratase and GDP-fucose transporter.

Although antibodies have attracted attention as next-generation biopharmaceuticals, the costs of purifying the products and of arranging the environment for cell cultivation are high. Therefore, there is a need to increase antibody efficacy and improve product quality as much as possible. Since antibodies are glycoproteins, their glycan structures have been found to affect the function of antibodies. Especially, afucosylation of the N-linked glycan in the Fc region is known to significantly increase antibody-dependent cellular cytotoxicity. In this study, we established a double-mutant ΔGMDΔGFT in which GDP-mannose 4,6-dehydratase and GDP-fucose transporter were knocked out in Chinese hamster ovary cells, a platform for biopharmaceutical protein production. By adapting ΔGMDΔGFT cells to serum-free medium and constructing suspension-cultured cells, we established host CHO cells with no detected fucosylated glycans and succeeded in production of afucosylated antibodies. We also demonstrated that, in culture in the presence of serum, fucosylation occurs due to contamination from serum components. Furthermore, we found that afucosylation of glycans does not affect cell growth after adaptation to serum-free medium as compared to wild-type CHO cells growth and does not significantly affect the expression levels of other endogenous fucose metabolism-related enzyme genes. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10616-021-00501-3.

Post-progression survival after atezolizumab plus carboplatin and etoposide as first-line chemotherapy in small cell lung cancer has a significant impact on overall survival.

BACKGROUND: The effect of first-line chemotherapy on overall survival (OS) may be significantly influenced by subsequent therapy for patients with extensive disease small cell lung cancer (ED-SCLC). Therefore, we evaluated the relationship between progression-free survival (PFS), post-progression survival (PPS), and OS of ED-SCLC patients treated with atezolizumab plus carboplatin and etoposide as first-line therapy. METHODS: We analyzed the data of 57 patients with relapsed ED-SCLC treated with atezolizumab plus carboplatin and etoposide (AteCE) as first-line chemotherapy between August 2019 and September 2020. The respective correlations between PFS-OS and PPS-OS following first-line AteCE treatment were examined at the individual patient level. RESULTS: Spearman's rank correlation analysis and linear regression analysis showed that PPS strongly correlated with OS (r = 0.93, p < 0.05, R2  = 0.85) and that PFS moderately correlated with OS (r = 0.55, p < 0.05, R2  = 0.28). Performance status at relapse (0-1/≥2), number of cycles of atezolizumab maintenance therapy (<3/≥3), and platinum rechallenge chemotherapy all significantly positively correlated with PPS (p < 0.05). CONCLUSIONS: Upon comparing OS-PFS and OS-PPS in this patient population, OS and PPS were found to have a stronger correlation. These results suggest that performance status at relapse, atezolizumab maintenance, or chemotherapy rechallenge could affect PPS.

Glial insulin regulates cooperative or antagonistic Golden goal/Flamingo interactions during photoreceptor axon guidance.

Transmembrane protein Golden goal (Gogo) interacts with atypical cadherin Flamingo (Fmi) to direct R8 photoreceptor axons in the Drosophila visual system. However, the precise mechanisms underlying Gogo regulation during columnar- and layer-specific R8 axon targeting are unknown. Our studies demonstrated that the insulin secreted from surface and cortex glia switches the phosphorylation status of Gogo, thereby regulating its two distinct functions. Non-phosphorylated Gogo mediates the initial recognition of the glial protrusion in the center of the medulla column, whereas phosphorylated Gogo suppresses radial filopodia extension by counteracting Flamingo to maintain a one axon-to-one column ratio. Later, Gogo expression ceases during the midpupal stage, thus allowing R8 filopodia to extend vertically into the M3 layer. These results demonstrate that the long- and short-range signaling between the glia and R8 axon growth cones regulates growth cone dynamics in a stepwise manner, and thus shapes the entire organization of the visual system.

Netrin Signaling Defines the Regional Border in the Drosophila Visual Center.

The brain consists of distinct domains defined by sharp borders. So far, the mechanisms of compartmentalization of developing tissues include cell adhesion, cell repulsion, and cortical tension. These mechanisms are tightly related to molecular machineries at the cell membrane. However, we and others demonstrated that Slit, a chemorepellent, is required to establish the borders in the fly brain. Here, we demonstrate that Netrin, a classic guidance molecule, is also involved in the compartmental subdivision in the fly brain. In Netrin mutants, many cells are intermingled with cells from the adjacent ganglia penetrating the ganglion borders, resulting in disorganized compartmental subdivisions. How do these guidance molecules regulate the compartmentalization? Our mathematical model demonstrates that a simple combination of known guidance properties of Slit and Netrin is sufficient to explain their roles in boundary formation. Our results suggest that Netrin indeed regulates boundary formation in combination with Slit in vivo.

Two receptor tyrosine phosphatases dictate the depth of axonal stabilizing layer in the visual system.

Formation of a functional neuronal network requires not only precise target recognition, but also stabilization of axonal contacts within their appropriate synaptic layers. Little is known about the molecular mechanisms underlying the stabilization of axonal connections after reaching their specifically targeted layers. Here, we show that two receptor protein tyrosine phosphatases (RPTPs), LAR and Ptp69D, act redundantly in photoreceptor afferents to stabilize axonal connections to the specific layers of the Drosophila visual system. Surprisingly, by combining loss-of-function and genetic rescue experiments, we found that the depth of the final layer of stable termination relied primarily on the cumulative amount of LAR and Ptp69D cytoplasmic activity, while specific features of their ectodomains contribute to the choice between two synaptic layers, M3 and M6, in the medulla. These data demonstrate how the combination of overlapping downstream but diversified upstream properties of two RPTPs can shape layer-specific wiring.