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  • Proceedings of the National Academy of Sciences  (8)
  • 1
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 96, No. 14 ( 1999-07-06), p. 8064-8069
    Abstract: Loss of imprinting at IGF2 , generally through an H19 -independent mechanism, is associated with a large percentage of patients with the overgrowth and cancer predisposition condition Beckwith–Wiedemann syndrome (BWS). Imprinting control elements are proposed to exist within the KvLQT1 locus, because multiple BWS-associated chromosome rearrangements disrupt this gene. We have identified an evolutionarily conserved, maternally methylated CpG island ( KvDMR1 ) in an intron of the KvLQT1 gene. Among 12 cases of BWS with normal H19 methylation, 5 showed demethylation of KvDMR1 in fibroblast or lymphocyte DNA; whereas, in 4 cases of BWS with H19 hypermethylation, methylation at KvDMRl was normal. Thus, inactivation of H19 and hypomethylation at KvDMR1 (or an associated phenomenon) represent distinct epigenetic anomalies associated with biallelic expression of IGF2 . Reverse transcription–PCR analysis of the human and syntenic mouse loci identified the presence of a KvDMR1 -associated RNA transcribed exclusively from the paternal allele and in the opposite orientation with respect to the maternally expressed KvLQT1 gene. We propose that KvDMR1 and/or its associated antisense RNA ( KvLQT1-AS ) represents an additional imprinting control element or center in the human 11p15.5 and mouse distal 7 imprinted domains.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
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    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 1999
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 1996
    In:  Proceedings of the National Academy of Sciences Vol. 93, No. 18 ( 1996-09-03), p. 9850-9857
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 93, No. 18 ( 1996-09-03), p. 9850-9857
    Abstract: Four new members of the fibroblast growth factor (FGF) family, referred to as fibroblast growth factor homologous factors (FHFs), have been identified by a combination of random cDNA sequencing, data base searches, and degenerate PCR. Pairwise comparisons between the four FHFs show between 58% and 71% amino acid sequence identity, but each FHF shows less than 30% identity when compared with other FGFs. Like FGF-1 (acidic FGF) and FGF-2 (basic FGF), the FHFs lack a classical signal sequence and contain clusters of basic residues that can act as nuclear localization signals. In transiently transfected 293 cells FHF-1 accumulates in the nucleus and is not secreted. Each FHF is expressed in the developing and adult nervous systems, suggesting a role for this branch of the FGF family in nervous system development and function.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
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    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 1996
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 3
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2022
    In:  Proceedings of the National Academy of Sciences Vol. 119, No. 52 ( 2022-12-27)
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 119, No. 52 ( 2022-12-27)
    Abstract: Sensorimotor learning is a dynamic, systems-level process that involves the combined action of multiple neural systems distributed across the brain. Although much is known about the specialized cortical systems that support specific components of action (such as reaching), we know less about how cortical systems function in a coordinated manner to facilitate adaptive behavior. To address this gap, our study measured human brain activity using functional MRI (fMRI) while participants performed a classic sensorimotor adaptation task and used a manifold learning approach to describe how behavioral changes during adaptation relate to changes in the landscape of cortical activity. During early adaptation, areas in the parietal and premotor cortices exhibited significant contraction along the cortical manifold, which was associated with their increased covariance with regions in the higher-order association cortex, including both the default mode and fronto-parietal networks. By contrast, during Late adaptation, when visuomotor errors had been largely reduced, a significant expansion of the visual cortex along the cortical manifold was associated with its reduced covariance with the association cortex and its increased intraconnectivity. Lastly, individuals who learned more rapidly exhibited greater covariance between regions in the sensorimotor and association cortices during early adaptation. These findings are consistent with a view that sensorimotor adaptation depends on changes in the integration and segregation of neural activity across more specialized regions of the unimodal cortex with regions in the association cortex implicated in higher-order processes. More generally, they lend support to an emerging line of evidence implicating regions of the default mode network (DMN) in task-based performance.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
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    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2022
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 4
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2018
    In:  Proceedings of the National Academy of Sciences Vol. 115, No. 50 ( 2018-12-11)
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 115, No. 50 ( 2018-12-11)
    Abstract: β-Catenin signaling controls the development and maintenance of the blood–brain barrier (BBB) and the blood–retina barrier (BRB), but the division of labor and degree of redundancy between the two principal ligand–receptor systems—the Norrin and Wnt7a/Wnt7b systems—are incompletely defined. Here, we present a loss-of-function genetic analysis of postnatal BBB and BRB maintenance in mice that shows striking threshold and partial redundancy effects. In particular, the combined loss of Wnt7a and Norrin or Wnt7a and Frizzled4 (Fz4) leads to anatomically localized BBB defects that are far more severe than observed with loss of Wnt7a, Norrin, or Fz4 alone. In the cerebellum, selective loss of Wnt7a in glia combined with ubiquitous loss of Norrin recapitulates the phenotype observed with ubiquitous loss of both Wnt7a and Norrin, implying that glia are the source of Wnt7a in the cerebellum. Tspan12, a coactivator of Norrin signaling in the retina, is also active in BBB maintenance but is less potent than Norrin, consistent with a model in which Tspan12 enhances the amplitude of the Norrin signal in vascular endothelial cells. Finally, in the context of a partially impaired Norrin system, the retina reveals a small contribution to BRB development from the Wnt7a/Wnt7b system. Taken together, these experiments define the extent of CNS region-specific cooperation for several components of the Norrin and Wnt7a/Wnt7b systems, and they reveal substantial regional heterogeneity in the extent to which partially redundant ligands, receptors, and coactivators maintain the BBB and BRB.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2018
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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  • 5
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 1990
    In:  Proceedings of the National Academy of Sciences Vol. 87, No. 6 ( 1990-03), p. 2329-2333
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 87, No. 6 ( 1990-03), p. 2329-2333
    Abstract: The signal-transducing guanine nucleotide-binding regulatory (G) proteins are heterotrimers composed of three subunits--alpha, beta, and gamma. Although multiple distinctive forms of the alpha subunit have been described, only two forms of the beta subunits of the G proteins have been identified. To investigate further the structural diversity of the beta subunits, we screened bovine and human retina cDNA libraries and isolated clones encoding three distinct types of G protein beta subunit. One form was identical to previously isolated beta 1-subunit cDNA clones that encode the 36-kDa form of the beta subunit, whereas a second form was identical to previously described beta 2 cDNAs that encode the 35-kDa beta isoform. In addition, we identified another species, designated beta 3 subunit, which encodes a third distinct form of the beta subunit. The beta 3-subunit cDNA corresponds to a 2.0-kilobase mRNA expressed in all tissues and clonal cell lines examined. Nucleotide sequence analysis indicates that the encoded peptide consists of 340-amino acid residues with a Mr of 37,221. The amino acid sequences of the three beta subunits are closely related: 83% identity between beta 1 and beta 3 subunits and 81% identity between beta 2 and beta 3 subunits. By contrast, the 3'-untranslated regions of the three cDNAs show no significant homology. Our data support the hypothesis that a family of beta-subunit polypeptides exists and extend understanding of beta-subunit structure.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 1990
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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  • 6
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 1997
    In:  Proceedings of the National Academy of Sciences Vol. 94, No. 7 ( 1997-04), p. 2859-2863
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 94, No. 7 ( 1997-04), p. 2859-2863
    Abstract: This paper describes the identification of a new family of mammalian genes that encode secreted proteins containing homology to the cysteine-rich ligand-binding domain found in the frizzled family of transmembrane receptors. The secreted frizzled-related proteins (sFRPs) are approximately 30 kDa in size, and each contains a putative signal sequence, a frizzled-like cysteine-rich domain, and a conserved hydrophilic carboxy-terminal domain. The sFRPs are not the products of differential splicing of the known frizzled genes. Glycosylphosphatidylinositol-anchored derivatives of sFRP-2 and sFRP-3 produced in transfected human embryonic kidney cells confer cell-surface binding by the Drosophila Wingless protein. These observations suggest that sFRPs may function in vivo to modulate Wnt signaling, or, alternatively, as novel ligands for as yet unidentified receptors.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 1997
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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  • 7
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 1990
    In:  Proceedings of the National Academy of Sciences Vol. 87, No. 24 ( 1990-12), p. 9893-9897
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 87, No. 24 ( 1990-12), p. 9893-9897
    Abstract: The role of protein kinase C (PKC) as a mediator of glucose-induced insulin secretion has been a subject of controversy. Glucose-induced translocation of PKC has not been reported, and the relevant PKC isoenzymes in islets have not been identified. To address these issues, we developed specific antibodies to the alpha, beta, and gamma isoenzymes of PKC. Western blots of homogenates of freshly isolated rat islets probed with these antibodies revealed that the major isoenzyme present is alpha-PKC. Islets were perifused for 15 min with either 2.75 mM glucose, 20 mM glucose, 20 mM glucose plus 30 mM mannoheptulose, 15 mM alpha-ketoisocaproate, or alpha-ketoisocaproate plus mannoheptulose. Quantitative immunoblotting of membrane and cytosol fractions showed that alpha-PKC translocated from the cytosol to the membrane in freshly isolated rat islets stimulated with either 20 mM glucose or 15 mM alpha-ketoisocaproate. Both the secretory response and the translocation of alpha-PKC were blocked by the addition of mannoheptulose, an inhibitor of glucose metabolism, in islets stimulated with glucose but not in islets stimulated with alpha-ketoisocaproate. These results support a role for alpha-PKC in mediating glucose-induced insulin secretion in pancreatic islets.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 1990
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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  • 8
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 115, No. 48 ( 2018-11-27), p. 12295-12300
    Abstract: The human default mode network (DMN) is implicated in several unique mental capacities. In this study, we tested whether brain-wide interregional communication in the DMN can be derived from population variability in intrinsic activity fluctuations, gray-matter morphology, and fiber tract anatomy. In a sample of 10,000 UK Biobank participants, pattern-learning algorithms revealed functional coupling states in the DMN that are linked to connectivity profiles between other macroscopical brain networks. In addition, DMN gray matter volume was covaried with white matter microstructure of the fornix. Collectively, functional and structural patterns unmasked a possible division of labor within major DMN nodes: Subregions most critical for cortical network interplay were adjacent to subregions most predictive of fornix fibers from the hippocampus that processes memories and places.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2018
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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