Typical pseudo-relevance feedback methods assume the topretrieved documents are relevant and use these pseudo-relevant documents to expand terms. The initial retrieval set can, however, contain a great deal of noise. In this paper, we present a clusterbased resampling method to select better pseudo-relevant documents based on the relevance model. The main idea is to use document clusters to find dominant documents for the initial retrieval set, and to repeatedly feed the documents to emphasize the core topics of a query. Experimental results on large-scale web TREC collections show significant improvements over the relevance model. For justification of the resampling approach, we examine relevance density of feedback documents. A higher relevance density will result in greater retrieval accuracy, ultimately approaching true relevance feedback. The resampling approach shows higher relevance density than the baseline relevance model on all collections, resulting in better retrieval accuracy in pseudo-relevance feedback. This result indicates that the proposed method is effective for pseudo-relevance feedback.

α 1D -Adrenergic receptors (ARs) are key regulators of cardiovascular system function that increase blood pressure and promote vascular remodeling. Unfortunately, little information exists about the signaling pathways used by this important G protein-coupled receptor (GPCR). We recently discovered that α 1D -ARs form a “signalosome” with multiple members of the dystrophin-associated protein complex (DAPC) to become functionally expressed at the plasma membrane and bind ligands. However, the molecular mechanism by which the DAPC imparts functionality to the α 1D -AR signalosome remains a mystery. To test the hypothesis that previously unidentified molecules are recruited to the α 1D -AR signalosome, we performed an extensive proteomic analysis on each member of the DAPC. Bioinformatic analysis of our proteomic data sets detected a common interacting protein of relatively unknown function, α-catulin. Coimmunoprecipitation and blot overlay assays indicate that α-catulin is directly recruited to the α 1D -AR signalosome by the C-terminal domain of α-dystrobrevin-1 and not the closely related splice variant α-dystrobrevin-2. Proteomic and biochemical analysis revealed that α-catulin supersensitizes α 1D -AR functional responses by recruiting effector molecules to the signalosome. Taken together, our study implicates α-catulin as a unique regulator of GPCR signaling and represents a unique expansion of the intricate and continually evolving array of GPCR signaling networks.

Mammalian MBNL (muscleblind-like) proteins are regulators of alternative splicing and have been implicated in myotonic dystrophy, the most common form of adult onset muscular dystrophy. MBNL3 functions as an inhibitor of muscle differentiation and is expressed in proliferating muscle precursor cells but not in differentiated skeletal muscle. Here we demonstrate that MBNL3 regulates the splicing pattern of the muscle transcription factor myocyte enhancer factor 2 (Mef2) by promoting exclusion of the alternatively spliced ␤-exon. Expression of the transcriptionally more active (؉)␤ isoform of Mef2D was sufficient to overcome the inhibitory effects of MBNL3 on muscle differentiation. These data suggest that MBNL3 antagonizes muscle differentiation by disrupting Mef2 ␤-exon splicing. MBNL3 regulates Mef2D splicing by directly binding to intron 7 downstream of the alternatively spliced exon in the pre-mRNA. The RNA binding activity of MBNL3 requires the CX 7 CX 4 -6 CX 3 H zinc finger domains. Using a cell culture model of myotonic dystrophy and myotonic dystrophy patient tissue, we have evidence that expression of CUG expanded RNAs can lead to an increase in MBNL3 expression and a decrease in Mef2D ␤-exon splicing. These studies suggest that elevating MBNL3 activity in myogenic cells could lead to muscle degeneration disorders such as myotonic dystrophy.

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The ␣ 1D -adrenergic receptor (ADRA1D) is a key regulator of cardiovascular, prostate, and central nervous system functions. This clinically relevant G protein-coupled receptor has proven difficult to study, as it must form an obligate modular homodimer containing the PDZ proteins scribble and syntrophin or become retained in the endoplasmic reticulum as nonfunctional protein. We previously determined that targeted removal of the N-terminal (NT) 79 amino acids facilitates ADRA1D plasma membrane expression and agonist-stimulated functional responses. However, whether such an event occurs in physiological contexts was unknown. Herein, we report the ADRA1D is subjected to innate NT processing in cultured human cells. SNAP near-infrared imaging and tandem-affinity purification revealed the ADRA1D is expressed as both fulllength and NT truncated forms in multiple human cell lines. Serial truncation mapping identified the cleavage site as Leu 90 / Val 91 in the 95-amino acid ADRA1D NT domain, suggesting human cells express a ⌬1-91 ADRA1D species. Tandem-affinity purification MS/MS and co-immunoprecipitation analysis indicate NT processing of ADRA1D is not required to form scribble-syntrophin macromolecular complexes. Yet, label-free dynamic mass redistribution signaling assays demonstrate that ⌬1-91 ADRA1D agonist responses were greater than WT ADRA1D. Mutagenesis of the cleavage site nullified the processing event, resulting in ADRA1D agonist responses less than the WT receptor. Thus, we propose that processing of the ADRA1D NT domain is a physiological mechanism employed by cells to generate a functional ADRA1D isoform with optimal pharmacodynamic properties.␣ 1 -Adrenergic receptors (ARs) 6 belong to the superfamily of class A G protein-coupled receptors (GPCRs). Stimulated by the endogenous catecholamines norepinephrine and epinephrine, ␣ 1 -ARs help coordinate sympathetic nervous function along with the ␣ 2 -and ␤-AR subtypes. This mode of GPCR signaling is particularly relevant during stress, exercise, or lifethreatening situations, as it permits an organism to respond to environmental stimuli supra-maximally and thereby enhance survival probability.Significant gaps remain in our understanding of ␣ 1 -AR biology. Of particular note is the ␣ 1D -AR subtype (ADRA1D). Unlike the closely related ␣ 1A (ADRA1A) and ␣ 1B (ADRA1B) subtypes, which achieve significant plasma membrane expression and robustly respond to agonists in cultured cells, the ADRA1D is cumbersome to study in vitro (1). Following its initial cloning and pharmacological characterization (2-4), numerous studies revealed the ADRA1D is sequestered intracellularly in myriad cell lines (5-11), where it has limited access to agonists and displays minimal functional activity. In a key study, Fan et al. (12) demonstrated ADRA1D functional expression is lost in cultured aortic vascular muscle cells ϳ48 h postdissection. They concluded that factors required for ADRA1D functional expression in vivo are absent in cell culture conditions (12), which may explain ...

Muscleblind-like (MBNL) proteins are believed to be regulators of myogenesis and are implicated in myotonic dystrophy. While Drosophila melanogaster muscleblind is required for terminal muscle differentiation, mammalian MBNL3 functions as an inhibitor of myogenesis. In this study, we analyzed the expression pattern of MBNL3 in different adult mouse tissues and tissue culture cells. MBNL3 transcript is enriched in the lung, spleen, and testis and not in heart and skeletal muscle. By western blotting, we found that MBNL3 was expressed in C2C12 myoblasts and ts13 myofibroblasts, but was detected at significantly lower levels in fibroblasts. MBNL3 protein levels decreased when cells were shifted to muscle differentiation conditions, but the closely related MBNL1 protein was unaffected. These results suggest that myoblasts and fibroblasts respond to differentiation conditions by activating signaling pathways that repress MBNL3 but not MBNL1 expression.

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