Region Of Chr Research Articles

Conformational analysis of a new peptide derived from feline immunodeficiency virus gp36 in SDS micelles: An NMR-MD based investigation.

Feline immunodeficiency virus (FIV) shares structural similarities with human immunodeficiency virus (HIV): the surface glycoprotein gp36 corresponds to the HIV gp41, which drives virus-host cell interactions and is targeted by the peptide entry inhibitor enfuvirtide. Following a similar drug design strategy for the development of an anti-FIV therapy, the present study investigates 627-646gp36 NHR, a peptide sequence derived from a region of gp36 that was previously found to interfere with the antiviral activity of the peptide C8, which instead derives from the gp36 MPER. CD, NMR, and MD simulations were employed to probe the conformational characteristics of 627-646gp36 NHR in the membrane-mimicking environment of SDS micelles. Our data show that 627-646gp36 NHR is characterized by three dynamic helix structures. MD simulations involving 627-646gp36 NHR, C8, and a larger protein, including the CHR and MPER regions, suggest that the interaction of C8 with the MPER region, the origin of the antiviral activity of C8, is disfavored in the presence of 627-646gp36 NHR in the simulation. This evidence can be useful for interpreting the molecular mechanism that leads to interference with the activity of C8, providing information on the folding/unfolding mechanism of the viral glycoprotein to design new strategies to inhibit viral entry.

Structural Basis of HIV-1 gp41 N-trimer for Designing Bifunctional Peptide-based Fusion Inhibitors.

Pathogenic viruses that cause large-scale global or regional outbreaks almost always contain class I fusion proteins. Although the viruses differ in morphology, they all require fusion protein-mediated virus-host cell membranes during the early stages of host cell invasion. The CHR region and NHR region of fusion proteins can form the 6-HB structure to drive the fusion pore formation between viruses and host cells through metastable interactions. Here, we obtained bifunctional N-peptides with inhibitory activities against two viruses, HIV-1 and MERS-CoV, based on the sequences in the HIV-1 NHR region by constructing N-trimer conformation interacting with the CHR region. This study demonstrates that N-peptides with the coiled triple helix structure obtained from the NHR region in 6-HB are able to target the CHR region and exhibit inhibitory activity against a variety of viruses. Moreover, this strategy can be used to investigate antivirals against unknown viruses for future outbreaks.

Digital PCR quantification of ultrahigh ERBB2 copy number identifies poor breast cancer survival after trastuzumab

HER2/ERBB2 evaluation is necessary for treatment decision-making in breast cancer (BC), however current methods have limitations and considerable variability exists. DNA copy number (CN) evaluation by droplet digital PCR (ddPCR) has complementary advantages for HER2/ERBB2 diagnostics. In this study, we developed a single-reaction multiplex ddPCR assay for determination of ERBB2 CN in reference to two control regions, CEP17 and a copy-number-stable region of chr. 2p13.1, validated CN estimations to clinical in situ hybridization (ISH) HER2 status, and investigated the association of ERBB2 CN with clinical outcomes. 909 primary BC tissues were evaluated and the area under the curve for concordance to HER2 status was 0.93 and 0.96 for ERBB2 CN using either CEP17 or 2p13.1 as reference, respectively. The accuracy of ddPCR ERBB2 CN was 93.7% and 94.1% in the training and validation groups, respectively. Positive and negative predictive value for the classic HER2 amplification and non-amplification groups was 97.2% and 94.8%, respectively. An identified biological “ultrahigh” ERBB2 ddPCR CN group had significantly worse survival within patients treated with adjuvant trastuzumab for both recurrence-free survival (hazard ratio, HR: 3.3; 95% CI 1.1–9.6; p = 0.031, multivariable Cox regression) and overall survival (HR: 3.6; 95% CI 1.1–12.6; p = 0.041). For validation using RNA-seq data as a surrogate, in a population-based SCAN-B cohort (NCT02306096) of 682 consecutive patients receiving adjuvant trastuzumab, the ultrahigh-ERBB2 mRNA group had significantly worse survival. Multiplex ddPCR is useful for ERBB2 CN estimation and ultrahigh ERBB2 may be a predictive factor for decreased long-term survival after trastuzumab treatment.

BSA‑seq and genetic mapping identified candidate genes for branching habit in peanut.

The candidate gene AhLBA1 controlling lateral branch angel of peanut was fine-mapped to a 136.65-kb physical region on chromosome 15 using the BSA-seq and QTL mapping. Lateral branch angel (LBA) is an important plant architecture trait of peanut, which plays key role in lodging, peg soil penetration and pod yield. However, there are few reports of fine mapping and quantitative trait loci (QTLs)/cloned genes for LBA in peanut. In this project, a mapping population was constructed using a spreading variety Tifrunner and the erect variety Fuhuasheng. Through bulked segregant analysis sequencing (BSA-seq), a major gene related to LBA, named as AhLBA1, was preliminarily mapped at the region of Chr.15: 150-160Mb. Then, using traditional QTL approach, AhLBA1 was narrowed to a 1.12cM region, corresponding to a 136.65-kb physical interval of the reference genome. Of the nine genes housed in this region, three of them were involved in hormone metabolism and regulation, including one "F-box protein" and two "2-oxoglutarate (2OG) and Fe(II)-dependent oxygenase (2OG oxygenase)" encoding genes. In addition, we found that the level of some classes of cytokinin (CK), auxin and ethylene showed significant differences between spreading and erect peanuts at the junction of main stem and lateral branch. These findings will aid further elucidation of the genetic mechanism of LBA in peanut and facilitating marker-assisted selection (MAS) in the future breeding program.

Structural and Mechanistic Evidence for Calcium Interacting Sites in the HIV Transmembrane Protein gp41 Involved in Membrane Fusion.

The HIV envelope protein gp160 comprises two subunits, gp120 and gp41, responsible for receptor binding and membrane fusion during viral entry, respectively. In the course of the membrane fusion process, gp41 undergoes a conformational change, leading to the formation of a six-helix bundle (SHB), which ultimately drives membrane fusion. The gp41 C-terminal and N-terminal heptad repeats (CHR and NHR) interact with one another to form the SHB, and this step can be targeted by peptide inhibitors, which are used in the clinic to mitigate HIV infection. Here, we discover the calcium interaction motifs (CIMs) in the gp41 CHR and NHR regions via NMR spectroscopy. We find that the assembly of the CHR–NHR SHB is facilitated in Ca2+-containing media and impaired in CIM mutants. Of note, the clinically approved, gp41-derived fusion inhibitor T20, which does not contain the CIM motif, exhibits reduced inhibitory efficiency when challenged with calcium. This finding could have important implications for the development of better fusion inhibitors for HIV.

In Vitro Selection and Characterization of HIV-1 Variants with Increased Resistance to LP-40, Enfuvirtide-Based Lipopeptide Inhibitor.

In our previous work, we replaced the TRM (tryptophan-rich motif) of T20 (Enfuvirtide) with fatty acid (C16) to obtain the novel lipopeptide LP-40, and LP-40 displayed enhanced antiviral activity. In this study, we investigated whether the C16 modification could enhance the high-resistance barrier of the inhibitor LP-40. To address this question, we performed an in vitro simultaneous screening of HIV-1NL4-3 resistance to T20 and LP-40. The mechanism of drug resistance for HIV-1 Env was further studied using the expression and processing of the Env glycoprotein, the effect of the Env mutation on the entry and fusion ability of the virus, and an analysis of changes to the gp41 core structure. The results indicate that the LP-40 activity is enhanced and that it has a high resistance barrier. In a detailed analysis of the resistance sites, we found that mutations in L33S conferred a stronger resistance, except for the well-recognized mutations in amino acids 36–45 of gp41 NHR, which reduced the inhibitory activity of the CHR-derived peptides. The compensatory mutation of eight amino acids in the CHR region (NDQEEDYN) plays an important role in drug resistance. LP-40 and T20 have similar resistance mutation sites, and we speculate that the same resistance profile may arise if LP-40 is used in a clinical setting.

Transcriptionally inactive hepatitis B virus episome DNA preferentially resides in the vicinity of chromosome 19 in 3D host genome upon infection

The hepatitis B virus (HBV) infects 257 million people worldwide. HBV infection requires establishment and persistence of covalently closed circular (ccc) DNA, a viral episome, in nucleus. Here, we study cccDNA spatial localization in the 3D host genome by using chromosome conformation capture-based sequencing analysis and fluorescence in situ hybridization (FISH). We show that transcriptionally inactive cccDNA is not randomly distributed in host nucleus. Rather, it is preferentially accumulated at specialized areas, including regions close to chromosome 19 (chr.19). Activation of the cccDNA is apparently associated with its re-localization, from a pre-established heterochromatin hub formed by 5 regions of chr.19 to transcriptionally active regions formed by chr.19 and nearby chromosomes including chr.16, 17, 20, and 22. This active versus inactive positioning at discrete regions of the host genome is primarily controlled by the viral HBx protein and by host factors including the structural maintenance of chromosomes protein 5/6 (SMC5/6) complex.

Probing Vulnerability of the gp41 C-Terminal Heptad Repeat as Target for Miniprotein HIV Inhibitors

One of the therapeutic strategies in HIV neutralization is blocking membrane fusion. In this process, tight interaction between the N-terminal and C-terminal heptad-repeat (NHR and CHR) regions of gp41 is essential to promote membranes apposition and merging. We have previously developed single-chain proteins (named covNHR) that accurately mimic the complete gp41 NHR region in its trimeric conformation. They tightly bind CHR-derived peptides and show a potent and broad HIV inhibitory activity in vitro. However, the extremely high binding affinity (sub-picomolar) is not in consonance with their inhibitory activity (nanomolar), likely due to partial or temporal accessibility of their target in the virus. Here, we have designed and characterized two single-chain covNHR miniproteins each encompassing one of the two halves of the NHR region and containing two of the four sub-pockets of the NHR crevice. The two miniproteins fold as trimeric helical bundles as expected but while the C-terminal covNHR (covNHR-C) miniprotein is highly stable, the N-terminal counterpart (covNHR-N) shows only marginal stability that could be improved by engineering an internal disulfide bond. Both miniproteins bind their respective complementary CHR peptides with moderate (micromolar) affinity. Moreover, the covNHR-N miniproteins can access their target in the context of trimeric native envelope proteins and show significant inhibitory activity for several HIV pseudoviruses. In contrast, covNHR-C cannot bind its target sequence and neither inhibits HIV, indicating a higher vulnerability of C-terminal part of CHR. These results may guide the development of novel HIV inhibitors targeting the gp41 CHR region.

Subcongenic Analysis of Quantitative Trait Loci Conferring Obesity and Hypercholesterolemia on Mouse Chromosome 1

Abstract Objectives The TALLYHO (TH) mouse is a polygenic model for obesity, type 2 diabetes and hyperlipidemia. We previously established a congenic mouse strain with TH donor segment on chromosome (Chr) 1 in a C57BL/6 J (B6) background that harbors quantitative trait loci (QTL) conferring obesity and hypercholesterolemia (The B6.TH-Chr1–128Mb). The congenic mouse developed increased adiposity and hypercholesterolemia and demonstrated that distal segment of Chr 1 from TH genome is necessary to cause both phenotypes. With the goal to identify the underlying genes regulating body fat and plasma cholesterol levels on mouse Chr 1, in this study we generated and characterized subcongenic lines with smaller TH donor segments. Methods Using the original B6.TH-Chr1–128Mb congenic mouse, we fixed three overlapping subcongenic lines over the distal region of Chr 1; one containing the full distal region of TH donor genome (39Mb in size) (B6.TH-Chr1–39Mb) and two nested overlapping lines (B6.TH-Chr1–30Mb and B6.TH-Chr1–20Mb). For mapping, all three lines of subcongenic mice and control B6 mice were weaned onto either chow or high fat (HF) diets at 4 weeks of age, and maintained on the respective diets. At 14 weeks of age, body composition including fat and lean mass was measured using EchoMRI-100 whole body composition analyzer, and plasma total cholesterol levels were determined using colorimetric assays. Data were analyzed by ANOVA using GraphPad Prism 8. Results On chow, body fat mass was not significantly different among all subcongenic mice and B6 mice. On HF diets, on the other hand, all three subcongenic lines of mice had significantly larger fat mass than B6 mice without genotype differences. These results suggest that the obesity candidate region is most likely located within the unique segment retained in B6.TH-Chr1–20Mb mice, delimited from the markers D1Mit105 and D1Mit361. Plasma total cholesterol levels were also significantly higher in B6.TH-Chr1–20Mb mice than them in B6 mice both on chow and HF diets. Conclusions We have created subcongenic lines, with smaller TH donor segments from the Chr 1 congenic interval, which develop detectable phenotypes, thus narrowing target intervals for positional cloning. Funding Sources This work was supported, in part, AHA 18AIREA33960437, NIH 1 R15 DK113604–01A1.

Genetic Effects on Dispersion in Urinary Albumin and Creatinine in Three House Mouse (Mus musculus) Cohorts.

Conventionally, quantitative genetics concerns the heredity of trait means, but there is growing evidence for the existence of architectures in which certain alleles cause random variance in phenotype, termed ‘phenotypic dispersion’ (PD) or ‘variance QTL’ (vQTL), including in physiological traits like disease signs. However, the structure of this phenomenon is still poorly known. PD for urinary albumin (PDUAlb) and creatinine (PDUCrea) was mapped using curated data from two nearly genetically identical F2 mouse (Mus musculus) cohorts (383 male F2 C57BL/6J×A/J (97 SNP) and 207 male F2 C57BL/6J×A/J ApoE knockout mice (144 SNP)) and a related mapping cohort (340 male F2 DBA/2J×C57BL/6J (83 SNP, 8 microsatellites)). PDUAlb was associated with markers in regions of Chr 1 (5-64 megabases (MB); 141-158 MB), 3 (∼113 MB), 8 (37-68 MB), 14 (92-117 MB) and 17 (14-24 MB) with several positions and quantitative architectures in common between the two C57BL/6J×A/J cohorts, most of which had a negative dominant construction. One locus for PDUCrea was detected on Chr 19 (57 MB) in the C57BL/6J×A/J ApoE−/− cohort. The large number of negative dominant loci for albuminuria dispersion relative to conventional quantitative trait loci suggests that the development of albuminuria may be largely genetically dynamic and that randomization in this development is detrimental.

The Origin of a New Sex Chromosome by Introgression between Two Stickleback Fishes.

Introgression is increasingly recognized as a source of genetic diversity that fuels adaptation. Its role in the evolution of sex chromosomes, however, is not well known. Here, we confirm the hypothesis that the Y chromosome in the ninespine stickleback, Pungitius pungitius, was established by introgression from the Amur stickleback, P. sinensis. Using whole genome resequencing, we identified a large region of Chr 12 in P. pungitius that is diverged between males and females. Within but not outside of this region, several lines of evidence show that the Y chromosome of P. pungitius shares a most recent common ancestor not with the X chromosome, but with the homologous chromosome in P. sinensis. Accumulation of repetitive elements and gene expression changes on the new Y are consistent with a young sex chromosome in early stages of degeneration, but other hallmarks of Y chromosomes have not yet appeared. Our findings indicate that porous species boundaries can trigger rapid sex chromosome evolution.

Identification of Introgressed Alleles Conferring High Fiber Quality Derived From Gossypium barbadense L. in Secondary Mapping Populations of G. hirsutum L.

The improvement of fiber quality is an essential goal in cotton breeding. In our previous studies, several quantitative trait loci (QTLs) contributing to improved fiber quality were identified in different introgressed chromosomal regions from Sea Island cotton (Gossypium barbadense L.) in a primary introgression population (Pop. A) of upland cotton (G. hirsutum L.). In the present study, to finely map introgressed major QTLs and accurately dissect the genetic contribution of the target introgressed chromosomal segments, we backcrossed two selected recombinant inbred lines (RILs) that presented desirable high fiber quality with their high lint-yielding recurrent parent to ultimately develop two secondary mapping populations (Pop. B and Pop. C). Totals of 20 and 27 QTLs for fiber quality were detected in Pop. B and Pop. C, respectively, including four and five for fiber length, four and eight for fiber micronaire, two and four for fiber uniformity, five and four for fiber elongation, and six and four for fiber strength, respectively. Two QTLs for lint percentage were detected only in Pop. C. In addition, seven stable QTLs were identified, including two for both fiber length and fiber strength and three for fiber elongation. Five QTL clusters for fiber quality were identified in the introgressed chromosomal regions, and negative effects of these chromosomal regions on lint percentage (a major lint yield parameter) were not observed. Candidate genes with a QTL-cluster associated with fiber strength and fiber length in the introgressed region of Chr.7 were further identified. The results may be helpful for revealing the genetic basis of superior fiber quality contributed by introgressed alleles from G. barbadense. Possible strategies involving marker-assisted selection (MAS) for simultaneously improving upland cotton fiber quality and lint yield in breeding programs was also discussed.

Opposing Tumor-Promoting and -Suppressive Functions of Rictor/mTORC2 Signaling in Adult Glioma and Pediatric SHH Medulloblastoma

SUMMARYMost human cancers arise from stem and progenitor cells by the sequential accumulation of genetic and epigenetic alterations, while cancer modeling typically requires simultaneous multiple oncogenic events. Here, we show that a single p53 mutation, despite causing no defect in the mouse brain, promoted neural stem and progenitor cells to spontaneously accumulate oncogenic alterations, including loss of multiple chromosomal (chr) regions syntenic to human chr10 containing Pten, forming malignant gliomas with PI3K/Akt activation. Rictor/mTORC2 loss inhibited Akt signaling, greatly delaying and reducing glioma formation by suppressing glioma precursors within the subventricular zone stem cell niche. Rictor/mTORC2 loss delayed timely differentiation of granule cell precursors (GCPs) during cerebellar development, promoting sustained GCP proliferation and medulloblastoma formation, which recapitulated critical features of TP53 mutant sonic hedgehog (SHH) medulloblastomas with GLI2 and/or N-MYC amplification. Our study demonstrates that Rictor/mTORC2 has opposing functions in neural stem cells and GCPs in the adult and the developing brain, promoting malignant gliomas and suppressing SHH-medulloblastoma formation, respectively.

Six-helix bundle completion in the distal C-terminal heptad repeat region of gp41 is required for efficient human immunodeficiency virus type 1 infection

BackgroundThe native pre-fusion structure of gp120/gp41 complex of human immunodeficiency virus type 1 was recently revealed. In the model, the helices of gp41 (α6, α7, α8, and α9) form a four-helix collar underneath trimeric gp120. Gp41 is a class I fusion protein and mediates membrane fusion by forming a post-fusion structure called the six-helix bundle (6HB). The comparison of the pre- and post-fusion structures revealed the large conformational changes in gp41 during the antiparallel packing of the N- and C-terminal heptad repeats (NHRs and CHRs) in membrane fusion. Several mutagenesis studies of gp41 performed in the past were interpreted based on 6HB, the only available structure at that time. To obtain an insight about the current pre-fusion structural model and conformational changes during membrane fusion, alanine insertion mutagenesis of the NHR, CHR and connecting loop regions of HXB2 gp41 was performed. The effects of mutations on biosynthesis and membrane fusion were analyzed by immunoblotting and fusion assays, respectively. The extent of membrane fusion was evaluated by split luciferase-based pore formation and syncytia formation assays, respectively.ResultsConsistent with the current structural model, drastic negative effects of mutations on biosynthesis and membrane fusion were observed for NHR, loop, and proximal regions of CHR (up to amino acid position 643). The insertions in α9 after it leaves the four-helix collar were tolerable for biosynthesis. These CHR mutants showed varying effects on membrane fusion. Insertion at position 644 or 645 resulted in poor pore and syncytia formation. Efficient pore and syncytia formation almost similar to that of the wild type was observed for insertion at position 647, 648 or 649. However, recovery of virus infectivity was only observed for the insertions beyond position 648.ConclusionsThe mutagenesis data for HXB2 gp41 is in agreement with the recent pre-fusion structure model. The virus infection data suggested that fusion pores sufficiently large enough for the release of the virus genome complex are formed after the completion of 6HB beyond position 648.

Congenic mice demonstrate the presence of QTLs conferring obesity and hypercholesterolemia on chromosome 1 in the TALLYHO mouse.

The TALLYHO (TH) mouse presents a metabolic syndrome of obesity, type 2 diabetes, and hyperlipidemia. Highly significant quantitative trait loci (QTLs) linked to adiposity and hypercholesterolemia were previously identified on chromosome (Chr) 1 in a genome-wide scan of F2 mice from C57BL/6J (B6) x TH. In this study, we generated congenic mouse strains that carry the Chr 1 QTLs derived from TH on a B6 background; B6.TH-Chr1-128Mb (128Mb in size) and B6.TH-Chr1-92Mb (92Mb in size, proximally overlapping). We characterized these congenic mice on chow and high fat (HF) diets. On chow, B6.TH-Chr1-128Mb congenic mice exhibited a slightly larger body fat mass compared with B6.TH-Chr1-92Mb congenic and B6 mice, while body fat mass between B6.TH-Chr1-92Mb congenic and B6 mice was comparable. Plasma total cholesterol levels were significantly higher in B6.TH-Chr1-128Mb congenics compared to B6.TH-Chr1-92Mb congenic and B6 mice. Again, there was no difference in plasma total cholesterol levels between B6.TH-Chr1-92Mb congenic and B6 mice. All animals gained more body fat and exhibited higher plasma total cholesterol levels when fed HF diets than fed chow, but these increases were greater in B6.TH-Chr1-128Mb congenics than in B6.TH-Chr1-92Mb congenic and B6 mice. These results confirmed the effect of the 128Mb TH segment from Chr 1 on body fat and plasma cholesterol values and showed that the distal segment of Chr 1 from TH is necessary to cause both phenotypes. Through bioinformatic approaches, we generated a list of potential candidate genes within the distal region of Chr 1 and tested Ifi202b and Apoa2. We conclude that Chr 1 QTLs largely confer obesity and hypercholesterolemia in TH mice and can be promising targets for identifying susceptibility genes. Congenic mouse strains will be a valuable resource for gene identification.

Climate Clever Clovers: New Paradigm to Reduce the Environmental Footprint of Ruminants by Breeding Low Methanogenic Forages Utilizing Haplotype Variation.

Mitigating methane production by ruminants is a significant challenge to global livestock production. This research offers a new paradigm to reduce methane emissions from ruminants by breeding climate-clever clovers. We demonstrate wide genetic diversity for the trait methanogenic potential in Australia’s key pasture legume, subterranean clover (Trifolium subterraneum L.). In a bi-parental population the broadsense heritability in methanogenic potential was moderate (H2 = 0.4) and allelic variation in a region of Chr 8 accounted for 7.8% of phenotypic variation. In a genome-wide association study we identified four loci controlling methanogenic potential assessed by an in vitro fermentation system. Significantly, the discovery of a single nucleotide polymorphism (SNP) on Chr 5 in a defined haplotype block with an upstream putative candidate gene from a plant peroxidase-like superfamily (TSub_g18548) and a downstream lectin receptor protein kinase (TSub_g18549) provides valuable candidates for an assay for this complex trait. In this way haplotype variation can be tracked to breed pastures with reduced methanogenic potential. Of the quantitative trait loci candidates, the DNA-damage-repair/toleration DRT100-like protein (TSub_g26967), linked to avoid the severity of DNA damage induced by secondary metabolites, is considered central to enteric methane production, as are disease resistance (TSub_g26971, TSub_g26972, and TSub_g18549) and ribonuclease proteins (TSub_g26974, TSub_g26975). These proteins are good pointers to elucidate the genetic basis of in vitro microbial fermentability and enteric methanogenic potential in subterranean clover. The genes identified allow the design of a suite of markers for marker-assisted selection to reduce rumen methane emission in selected pasture legumes. We demonstrate the feasibility of a plant breeding approach without compromising animal productivity to mitigate enteric methane emissions, which is one of the most significant challenges to global livestock production.

Abstract 109: Gamma-adducin Effects on Microvascular Function- a Common Link of Hypertension Induced Chronic Kidney Disease and Cognitive Impairments

Chronic kidney disease (CKD) and cognitive impairments are common complications of hypertension. Increasing evidence suggests that the cognitive impairments associated with CKD may be related to microvascular dysfunction, however, the underlying mechanisms remain to be elucidated. FHH is a genetic model of hypertension-induced nephropathy. We found that the myogenic response and autoregulation of the renal and cerebral circulation is impaired in FHH rats, and was restored in a FHH.1 BN congenic strain in which a small region of Chr. 1 containing 15 genes, including Add3, from BN rats was transferred into the FHH background. The present study examined whether Add3 contributes to hypertension related CKD, and is associated with the development of cognitive impairments due to microvascular dysfunction. FHH rats exhibited impaired autoregulation of RBF in comparison with FHH.1 BN rats. Pgc estimated from the stop flow pressure increased by 20 mmHg in FHH rats when RPP was increased from 100 to 140 mmHg versus only 4 mmHg in FHH.1 BN . FHH rats developed severe renal injury, and proteinuria rose from 37 ± 2 to 260 ± 32 mg/day as they aged from 12 to 21 weeks, but rose by a significant lesser extent in FHH.1 BN and FHH.Add3 rats. Glomerular injury scores were 3.31 ± 0.01, 2.54 ± 0.01 and 2.50 ± 0.03, and areas of fibrosis in renal cortex were 23.57 ± 1.04%, 8.28 ± 0.33 and 4.71 ± 0.3 in DOCA/salt induced hypertensive FHH, FHH.1 BN and FHH.Add3 rats, respectively. CBF rose by 99 ± 7%, 64 ± 5% and 42 ± 4% in FHH, FHH.1 BN and FHH.Add3 rats, respectively, when MAP was increased from 100 to 190 mmHg, demonstrating impaired autoregulation of CBF in FHH rats was partially rescued with the replacement of wildtype Add3. BBB leakage was greater in FHH rats than in FHH.1 BN and FHH.Add3 rats, and hypertensive FHH rats exhibited marked neurodegeneration and vascular remodeling of the neocortex and hippocampus. The hypertensive FHH rats took 2.5 times longer time to escape from an eight-arm water maze in comparison to FHH.1 BN rats suggesting cognitive deficit. These results indicate that Add3 may play a role in the development of hypertension related CKD and cognitive impairments in FHH rats associated with microvascular dysfunction.

Molecular features underlying response to neoadjuvant gemcitabine, cisplatin, and sorafenib (S-GC) in muscle-invasive urothelial bladder carcinoma (MIBC): Insights for trials of new agents combined with chemotherapy in the field.

e16018 Background: S-GC neoadjuvant chemotherapy (NACT) was active in a phase 2 trial in MIBC, showing a response rate (downstaging to pT < 2) of 54.3% in 46 pts within a single-arm, phase 2 trial ( Necchi et al, GU ASCO 2017). The addition of S to GC may help investigators unravelling key molecular features underlying response in MIBC. Methods: Analyses were made on pre- and post-treatment TURB and cystectomy (Cy) specimens (10µm sections) and matched germline DNA of 29/46 pts. Analyses included measurements of ERCC1 (by immunohistochemistry, IHC) on TURB specimens, baseline circulating VEGF levels (ELISA), copy number variations (CNV, Affymetrix), and next generation sequencing (NGS, custom gene panels through the Ion AmpliSeq Library Kit2.0™ and the Ion Torrent Personal Genome Machine™ platform). Results: We analyzed TURB samples from 15 responders (R) and 4 non-R (NR). An additional 10 Cy samples were used for NR. Baseline VEGF levels were not associated with PFS or OS on univariable analyses (p = 0.943 and p = 0.669, respectively). Differences in R vs. NR pts were found according to CNVs and NGS. CN gains on regions of chromosome (chr) 18 and 20 and loss in chr 5 were found in 56-60% of R and in none of the NR. Gains on regions of chr 3 and losses in chr 1 and 20 were more frequent in the NR ( > 50%) vs. R ( < 20%). The median number of somatic mutations (mut) per sample was 3 (range, 0-19). Missense mut in DNA-repair genes ( POLK; FANCM; PRKDC; BLM; MSH2; MSH6; RAD50) were found in 63.6% R vs 16.7% NR, in RAS-RAF pathway genes ( CDKN2A; RAC1; KRAS; NF1) in 45.4% vs 7.1%, in chromatin-remodelling genes ( ARID1A; ARID2; KDM5C; SMARCA4; ATRX; KMT2C; DAXX; SETD2) in 54.5% vs 16.7%, and in HER-family genes in R only (36.4%). ERCC1 IHC expression was found in 55.6% R vs 93.3% NR (p = 0.047). Conclusions: We identified distinct molecular features of R vs NR to S-GC in MIBC. These features may be linked to a potentially-additive effect of S and CT. The identification of the targets of CNVs will further elucidate the underlying biology. These results may help developing personalized medicine in MIBC with new more potent targeted agents with CT. Clinical trial information: NCT01222676.

QTL Mapping of Endocochlear Potential Differences between C57BL/6J and BALB/cJ mice.

We reported earlier that the endocochlear potential (EP) differs between C57BL/6J (B6) and BALB/cJ (BALB) mice, being lower in BALBs by about 10mV (Ohlemiller et al. Hear Res 220: 10-26, 2006). This difference corresponds to strain differences with respect to the density of marginal cells in cochlear stria vascularis. After about 1year of age, BALB mice also tend toward EP reduction that correlates with further marginal cell loss. We therefore suggested that early sub-clinical features of the BALB stria vascularis may predispose these mice to a condition modeling Schuknecht's strial presbycusis. We further reported (Ohlemiller et al. J Assoc Res Otolaryngol 12: 45-58, 2011) that the acute effects of a 2-h 110 dB SPL noise exposure differ between B6 and BALB mice, such that the EP remains unchanged in B6 mice, but is reduced by 40-50mV in BALBs. In about 25% of BALBs, the EP does not completely recover, so that permanent EP reduction may contribute to noise-induced permanent threshold shifts in BALBs. To identify genes and alleles that may promote natural EP variation as well as noise-related EP reduction in BALB mice, we have mapped related quantitative trait loci (QTLs) using 12 recombinant inbred (RI) strains formed from B6 and BALB (CxB1-CxB12). EP and strial marginal cell density were measured in B6 mice, BALB mice, their F1 hybrids, and RI mice without noise exposure, and 1-3 h after broadband noise (4-45 kHz, 110 dB SPL, 2 h). For unexposed mice, the strain distribution patterns for EP and marginal cell density were used to generate preliminary QTL maps for both EP and marginal cell density. Six QTL regions were at least statistically suggestive, including a significant QTL for marginal cell density on chromosome 12 that overlapped a weak QTL for EP variation. This region, termed Maced (Marginal cell density QTL) supports the notion of marginal cell density as a genetically influenced contributor to natural EP variation. Candidate genes for Maced notably include Foxg1, Foxa1, Akap6, Nkx2-1, and Pax9. Noise exposure produced significant EP reductions in two RI strains as well as significant EP increases in two RI strains. QTL mapping of the EP in noise-exposed RI mice yielded four suggestive regions. Two of these overlapped with QTL regions we previously identified for noise-related EP reduction in CBA/J mice (Ohlemiller et al. Hear Res 260: 47-53, 2010) on chromosomes 5 and 18 (Nirep). The present map may narrow the Nirep interval to a ~10-Mb region of proximal Chr. 18 that includes Zeb1, Arhgap12, Mpp7, and Gjd4. This study marks the first exploration of natural gene variants that modulate the EP. Their orthologs may underlie some human hearing loss that originates in the lateral wall.

Abstract MP14: A K572Q Mutation in Gamma-adducin Is Responsible for the Impaired Myogenic Response and Autoregulation of Renal and Cerebral Blood Flow in FHH Rats

The FHH rat is a genetic model of hypertension induced CKD, but the genes and pathways involved are unknown. We recently reported that the myogenic response of the renal and cerebral arteries is impaired in FHH rats and it was restored in a FHH.1BN congenic strain in which a small region of Chr. 1 containing 15 genes, including gamma-Adducin (Add3), from BN rats was transferred into the FHH background. We further identified a K572Q mutation in Add3 in FHH versus FHH.1BN rat. The present study examined the contribution of Add3 to the impaired myogenic reactivity using Add3 transgenic and KO rats. The diameter of the middle cerebral artery (MCA) decreased by 20-30% in SD, FHH.1BN and FHH.Add3 transgenic rats when perfusion pressure was increased from 40 to 140 mmHg. In contrast, the MCA of FHH and SD.Add3 knockout rats did not constrict. The myogenic response of the MCA is also impaired in MNS rats that share the same mutation in Add3 as in FHH rat and this phenotype was complemented in a F1 cross of FHH and MNS strain. Autoregulation of CBF was impaired in FHH rats and rose by 99 ± 7% when MAP was increased from 100 to 190 mmHg and was restored in FHH.Add3 and FHH.1BN rats. Similarly, the diameter of Af-art of FHH, MNS and a F1 cross of FHH and MNS rat increased in response to increase in perfusion pressure but decreased in FHH.1BN rats that have wild type Add3. FHH rats exhibited impaired autoregulation of RBF in comparison with FHH.1BN rats. Pgc estimated from the stopflow pressure increased by 20 mmHg in FHH rats when RPP was increased from 100 to 140 mmHg versus only 4 mmHg in the congenic strain. FHH rats developed severe renal injury and proteinuria rose from 37 ± 2 to 260 ± 32 mg/day as they aged from 12 to 21 weeks, but rose by a significant lesser extent in FHH.1BN and FHH.Add3 rats. BK current in VSMC isolated from the MCA was 5-fold higher in FHH vs. FHH.1BN rats. Administration of IBTX normalized the elevated BK channel current and restored the myogenic response in FHH rats but it had little effect in FHH.1BN. These results indicate that the K572Q mutation in Add3 plays a causal role in the impaired myogenic response and autoregulation of renal and cerebral circulation in FHH rats and may contribute to the development of renal and cerebral end organ damage with aging and after the onset of hypertension.