Down syndrome is a major cause of mental retardation and congenital heart defects and is due to the presence of three copies of human chromosome 21 in the affected individual. We have identified a gene, DSCR1 (HGMW-approved symbol), from the region 21q22.1-q22.2, which is highly expressed in human fetal brain and adult heart. Structural features of the conceptual protein encourage us to propose involvement of DSCR1 in the regulation of transcription and/or signal transduction. Higher expression of RNA in the brains of young rats compared to adults suggests a possible role for the gene in the development of the central nervous system. We have determined the genomic organization of DSCR1 and identified three additional alternative first exons by RACE and cDNA library screening. DSCR1 spans nearly 45 kb of genomic DNA and comprises seven exons, four of which (exons 1-4) are alternative first exons. All the exons are flanked by splice junctions that conform to the consensus AG-GT motif. We have studied the expression patterns of the alternative first exons. Exon 2 was detected in fetal brain and liver by RT-PCR. Both exons 1 and 4 were differentially expressed in fetal brain, lung, liver, and kidney and in all adult tissues tested by Northern analysis with two notable exceptions: exon 1 was not detected in adult kidney and exon 4 was not found in adult brain. The high level of expression of exon 1 in fetal brain suggests that this alternative form of DSCR1 has an important role in brain development. This information should help us to understand the possible relationship of DSCR1 with Down syndrome and aid in the development of animal models.
"near the minimal critical region implicated in the Down Syndrome phenotype . The gene consists of six exons, and codes for two major protein isoforms, each with a unique first exon, exon 1 (RCAN1-1) or exon 4 (RCAN1-4) and shared exons 5e7 . Additionally, exon 1 has two translation start codons, corresponding to a long and short variant: RCAN1-1L and RCAN1-1S. "
"RCAN1 is preferentially expressed in heart, skeletal muscle, and brain , and can bind to and inhibit calcineurin , . Ca2+/calmodulin-dependent protein phosphatase calcineurin mediates many cellular responses including lymphocyte activation and neuronal and muscle development . "
[Show abstract][Hide abstract] ABSTRACT: Regulator of calcineurin 1 (RCAN1; also referred as DSCR1 or MCIP1) is located in close proximity to a Down syndrome critical region of human chromosome 21. Although RCAN1 is an endogenous inhibitor of calcineurin signaling that controls lymphocyte activation, apoptosis, heart development, skeletal muscle differentiation, and cardiac function, it is not yet clear whether RCAN1 might be involved in other cellular activities. In this study, we explored the extra-functional roles of RCAN1 by searching for novel RCAN1-binding partners. Using a yeast two-hybrid assay, we found that RCAN1 (RCAN1-1S) interacts with histone deacetylase 3 (HDAC3) in mammalian cells. We also demonstrate that HDAC3 deacetylates RCAN1. In addition, HDAC3 increases RCAN1 protein stability by inhibiting its poly-ubiquitination. Furthermore, HDAC3 promotes RCAN1 nuclear translocation. These data suggest that HDAC3, a new binding regulator of RCAN1, affects the protein stability and intracellular localization of RCAN1.
PLoS ONE 08/2014; 9(8):e105416. DOI:10.1371/journal.pone.0105416 · 3.23 Impact Factor
"being highly expressed in the central nervous system (CNS) and isoform 4 (RCAN1.4) being mostly expressed in heart muscle and fetal kidney , , , . As an activating transcription factor 6 (ATF6) inducible gene, RCAN1 is activated under endoplasmic reticulum stress . "
[Show abstract][Hide abstract] ABSTRACT: Down Syndrome (DS) patients develop characteristic Alzheimer's Disease (AD) neuropathology after their middle age. Prominent neuronal loss has been observed in the cortical regions of AD brains. However, the underlying mechanism leading to this neuronal loss in both DS and AD remains to be elucidated. Calcium overloading and oxidative stress have been implicated in AD pathogenesis. Two major isoforms of regulator of calcineurin 1 (RCAN1), RCAN1.1 and RCAN1.4, are detected in human brains. In this report we defined the transcriptional regulation of RCAN1.1 and RCAN1.4 by two alternative promoters. Calcium overloading upregulated RCAN1.4 expression by activating RCAN1.4 promoter through calcineurin-NFAT signaling pathway, thus forming a negative feedback loop in isoform 4 regulation. Furthermore, RCAN1.4 overexpression exacerbated calcium overloading-induced neuronal apoptosis, which was mediated by caspase-3 apoptotic pathway. Our results suggest that downregulating RCAN1.4 expression in neurons could be beneficial to AD patients.
PLoS ONE 04/2014; 9(4):e95471. DOI:10.1371/journal.pone.0095471 · 3.23 Impact Factor
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