Decapentaplegic (dpp), a TGF beta-related ligand, plays a key role in Drosophila development. Although dpp receptors have been isolated, the downstream components of the signaling pathway remain to be identified. We have cloned the schnurri (shn) gene and show that it encodes a putative zinc finger transcription factor homologous to the human major histocompatibility complex-binding proteins 1 and 2. Mutations in shn affect multiple events that require dpp signaling as well as the transcription of dpp-responsive genes. Genetic interactions and the strikingly similar phenotypes of mutations in shn and the dpp receptors encoded by thick veins and punt suggest that shn plays a downstream role in dpp signaling.

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In Drosophila, a BMP-related ligand Decapentaplegic (Dpp) is essential for cell fate specification during embryogenesis and in imaginal disc development. Dpp signaling culminates in the phosphorylation and nuclear translocation of Mothers against dpp (Mad), a receptor-specific Smad that can bind DNA and regulate the transcription of Dpp-responsive genes. Genetic analysis has implicated Schnurri (Shn), a zinc finger protein that shares homology with mammalian transcription factors, in the Dpp signal transduction pathway. However, a direct role for Shn in regulating the transcriptional response to Dpp has not been demonstrated. In this study we show that Shn acts as a DNA-binding Mad cofactor in the nuclear response to Dpp. Shn can bind DNA in a sequence-specific manner and recognizes sites within a well-characterized Dpp-responsive promoter element, the B enhancer of the Ultrabithorax (Ubx) gene. The Shn-binding sites are relevant for in vivo expression, since mutations in these sites affect the ability of the enhancer to respond to Dpp. Furthermore we find that Shn and Mad can interact directly through discrete domains. To examine the relative contribution of the two proteins in the regulation of endogenous Dpp target genes we developed a cell culture assay and show that Shn and Mad act synergistically to induce transcription. Our results suggest that cooperative interactions between these two transcription factors could play an important role in the regulation of Dpp target genes. This is the first evidence that Dpp/BMP signaling in flies requires the direct interaction of Mad with a partner transcription factor.

Background: High tumor mutation burden (TMB) is an emerging selection biomarker for immune checkpoint blockade in tumors such as melanoma and non-small cell lung cancer. TMB is typically calculated from whole genome sequencing or whole exome sequencing (WES) data. Recently, clinical trials showed that TMB can also be estimated from targeted sequencing of a panel of only a few hundred genes of interest, which can be performed at a high depth for clinical applications. Materials and methods: In this study, we systematically investigated the distribution of TMB and preferences at the gene and mutation level, as well as the correlation between TMB calculated by WES and panel sequencing data using somatic mutation data from 15 cancer types from The Cancer Genome Atlas (TCGA). Results: We proposed a pan-cancer TMB panel and demonstrated that it had a higher correlation with WES than other panels. Our panel could serve as a reference data-set for TMB-oriented panel design to identify patients for immunotherapy.

1 The full-length, canine cholecystokinin 1 (CCK1) receptor was cloned from gallbladder tissue using RT-PCR with a combination of primers designed to interact with conserved regions of the human and rat CCK1 receptor, which also shared homology with the canine genomic sequence. . Furthermore, the selectivity of these compounds between canine CCK1 and CCK2 receptors was consistent with the selectivity between the human CCK1 and CCK2 receptors. 4 Two additional forms of the canine CCK1 receptor were identified during the cloning procedure. These had three (variant #1) and six (variant #2) amino-acid differences from the wild-type canine CCK1 receptor. Variant #1 bound [ 125 I]BH-CCK-8S and displayed an identical pharmacological profile to the wild-type receptor using the ligands described above. No significant binding was measured with variant #2. 5 In conclusion, we have cloned and pharmacologically characterized the canine CCK1 receptor. The data obtained will facilitate the interpretation of numerous pharmacological experiments that have been performed using canine tissue to elucidate the actions of CCK and gastrin.