Disease relevance of Ighmbp2

• Mutations in mouse Ighmbp2 (ref. 14) have been shown to be responsible for spinal muscular atrophy in the neuromuscular degeneration (nmd) mouse, whose phenotype resembles the SMARD1 phenotype [1].
• This study uniquely demonstrates that altered binding to the RIPE3b1 sequence mediates glucose toxicity in betaTC-6 cells, thus reinforcing the importance of this cis-acting element in the regulation of insulin gene transcription [2].
• The nmd mouse mutation causes progressive degeneration of spinal motor neurons and muscle atrophy [3].
• Characterization of Smubp-2 as a mouse mammary tumor virus promoter-binding protein [4].
• The recombinant Smubp-2 protein was expressed as a GST- or Trx-fusion protein in Escherichia coli and purified by affinity column chromatography [4].

High impact information on Ighmbp2

• Mutations in the gene encoding immunoglobulin mu-binding protein 2 cause spinal muscular atrophy with respiratory distress type 1 [1].
• Mutation of the RIPE3b1 binding site almost completely abolished insulin gene transcription as well as binding activity [2].
• ALDH(hi)SSC(lo) stem cells are self-renewing and multipotent and when intrathecally transplanted in nmd mice generate motor neurons properly localized in the spinal cord ventral horns [5].
• We investigated the potential of a spinal cord neural stem cell population isolated on the basis of aldehyde dehydrogenase (ALDH) activity to modify disease progression of nmd mice, an animal model of SMARD1 [5].
• Transplanted ALDHhiSSClo neural stem cells generate motor neurons and delay disease progression of nmd mice, an animal model of SMARD1 [5].

Chemical compound and disease context of Ighmbp2

• A cDNA encoding a rat Smubp-2 has been cloned from a lambdagt11 library by South-Western blot screening using a 50-bp tannic acid responsive element [J. Biol. Chem. 273 (1998) 12499] of the mouse mammary tumor virus (MMTV) promoter region as a probe [4].
• A factor in conditioned medium of rabbit costal chondrocytes inhibits the proliferation of cultured endothelial cells and angiogenesis induced by B16 melanoma: its relation with cartilage-derived anti-tumor factor (CATF) [6].
• Furthermore, phagocytosis and O2-dependent bactericidal systems were studied by measuring the chemiluminescence response from macrophages under exposure to L. monocytogenes and Staphylococcus aureus: the response was earlier and higher from AEP-stimulated macrophages than from controls [7].

Biological context of Ighmbp2

• In addition, the severity of the nmd phenotype is attenuated in a semidominant fashion by a major genetic locus on chromosome (Chr) 13 [3].
• Element B, the core enhancer sequence, was shown to interact specifically with a liver-enriched transcription factor, CCAAT/enhancer-binding protein alpha (C/EBPalpha), as well as a presumptive antifreeze enhancer-binding protein (AEP) [8].
• Northern blot analysis revealed that the gene expression of Smubp-2 is comparatively high in testis, moderate in brain, and low in other tissues [4].
• These results suggest that the negative transcriptional effect of Smubp-2 arises from its binding to the 50-bp element located in the MMTV promoter region [4].
• Mutation on one of the residues disrupted the binding between element B and AEP and its enhancer activity was significantly reduced, suggesting that AEP is essential for the transactivation of the wflAFP gene intron [8].

Anatomical context of Ighmbp2

• Characterization of Ighmbp2 in motor neurons and implications for the pathomechanism in a mouse model of human spinal muscular atrophy with respiratory distress type 1 (SMARD1) [9].
• To investigate the role of IGHMBP2 in the pathogenesis of DCM, we generated transgenic mice expressing the full-length Ighmbp2 cDNA specifically in myocytes under the control of the mouse titin promoter [10].
• We have generated antibodies against Ighmbp2 and showed that low levels of Ighmbp2 immunoreactivity are present in the nucleus of spinal motor neurons and high levels in cell bodies, axons and growth cones [9].
• Our results suggest that reduced levels of IGHMBP2 in nmd mice compromise the integrity and function not only of motor neurons but also of skeletal and cardiac myocytes [11].
• To further investigate the molecular events responsible for these differences, microarray and real-time reverse transcription-polymerase chain reaction analyses of wild-type, mutated and transplanted nmd spinal cord were undertaken [5].

Associations of Ighmbp2 with chemical compounds

• Chronic exposure of betaTC-6 cells to supraphysiologic concentrations of glucose decreases binding of the RIPE3b1 insulin gene transcription activator [2].
• MafA was detected in the C1/RIPE3b1 binding complex by using MafA peptide-specific antisera [12].
• The potential role of AEP in regulating the flounder AFP gene expression is discussed [8].
• Phosphatase inhibition of RIPE3b1 binding was prevented by sodium pyrophosphate, a general phosphatase inhibitor [13].
• However, p85 could not be detected in the same immunoprecipitates when the lysates had been preincubated with 1 mM peroxynitrite, indicating that the nitration of the p85 subunit may abrogate its interaction with the p110 subunit [14].

Other interactions of Ighmbp2

• These results strongly suggest that RIPE3b1/Maf has an important role in generating and maintaining physiologically functional beta cells [15].
• The islet beta cell-enriched RIPE3b1/Maf transcription factor regulates pdx-1 expression [15].
• The active mutant p110 subunit of PI3K has also been shown to enhance the CD44 cleavage, suggesting that PI3K mediates the Ras-induced CD44 cleavage [16].
• Incubating beta cell nuclear extracts with either calf alkaline phosphatase or a rat brain phosphatase preparation dramatically reduced RIPE3b1 DNA complex formation [13].

Analytical, diagnostic and therapeutic context of Ighmbp2

• In the present study, the C1/RIPE3b1 activator from mouse beta TC-3 cell nuclear extracts was purified by DNA affinity chromatography and two-dimensional gel electrophoresis [12].
• In addition, the chromatin immunoprecipitation assay showed that the Area II region of the endogenous pdx-1 gene was precipitated by an antiserum that recognizes the large Maf protein that comprises the RIPE3b1 transcription factor [15].
• The specific binding between element B and AEP was confirmed by South-Western analysis and gel retardation assays [8].

References