The subunits of voltage-gated calcium channels regulate surface expression and gating of CaV1 and CaV2 1 subunits, and thus contribute to neuronal excitability, neurotransmitter release and calcium-induced gene regulation. In addition certain subunits are targeted into the nucleus, where they directly interact with the epigenetic machinery. Whereas their involvement in this multitude of functions is reflected by a great molecular heterogeneity of isoforms derived from four genes and abundant alternative splicing, little is known about the roles of individual variants in specific neuronal functions. In the present study, an alternatively spliced 4 subunit lacking the variable N-terminus (4e) is identified. It is highly expressed in mouse cerebellum and cultured cerebellar granule cells (CGC) and modulates P/Q-type calcium currents in tsA cells and CaV2.1 surface expression in neurons. Compared to the other two known full-length 4 variants (4a, 4b) 4e is most abundantly expressed in the distal axon, but lacks nuclear targeting properties. To examine the importance of nuclear targeting of 4 subunits for transcriptional regulation, we performed whole genome expression profiling of CGCs from lethargic mice individually reconstituted with 4a, 4b, and 4e. Notably, the number of genes regulated by each 4 splice variant correlated with the rank order of their nuclear targeting properties (4b> 4a> 4e). Together these findings support isoform-specific functions of 4 splice variant in neurons, with 4b playing a dual role in channel modulation and gene regulation, while the newly detected 4e variant serves exclusively in calcium channel-dependent functions.
Differential neuronal targeting of a new and two known calcium channel β4 subunit splice variants correlates with their regulation of gene expression.
Specimen part
View SamplesNCoR and SMRT are two paralogous vertebrate proteins that function as corepressors with unliganded nuclear receptors. Although C. elegans has a large number of nuclear receptors, orthologues of the corepressors NCoR and SMRT have not unambiguously been identified in Drosophila or C. elegans. Here, we identify GEI-8 as the closest homologue of NCoR and SMRT in C. elegans and demonstrate that GEI-8 is expressed as at least two isoforms throughout development in multiple tissues, including neurons, muscle and intestinal cells. We demonstrate that a homozygous deletion within the gei-8 coding region, which is predicted to encode a truncated protein lacking the predicted NR domain, results in severe mutant phenotypes with developmental defects, slow movement and growth, arrested gonadogenesis and defects in cholinergic neurotransmission. Whole genome expression analysis by microarrays identified sets of de-regulated genes consistent with both the observed mutant phenotypes and a role of GEI-8 in regulating transcription. Interestingly, the upregulated transcripts included a predicted mitochondrial sulfide:quinine reductase encoded by Y9C9A.16. This locus also contains non-coding, 21-U RNAs of the piRNA. Inhibition of the expression of the region coding for 21-U RNAs leads to irregular gonadogenesis in the homozygous gei-8 mutants, but not in an otherwise wild-type background, suggesting that GEI-8 may function in concert with the 21-U RNAs to regulate gonadogenesis. Our results confirm that GEI-8 is the orthologue of the vertebrate NCoR/SMRT corepressors and demonstrate important roles for this putative transcriptional corepressor in development and neuronal function.
GEI-8, a homologue of vertebrate nuclear receptor corepressor NCoR/SMRT, regulates gonad development and neuronal functions in Caenorhabditis elegans.
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View SamplesNHR-23, a conserved member of the nuclear receptor family of transcription factors, is required for normal development in C. elegans where it plays a critical role in growth and molting. In a search for NHR-23 dependent genes, we performed whole genome comparative expression microarrays on both control and nhr-23 inhibited synchronized larvae. Genes that decreased in response to nhr-23 RNAi included several collagen genes. Unexpectedly, several hedgehog-related genes were also down-regulated after nhr-23 RNAi. A homozygous nhr-23 deletion allele was used to confirm the RNAi knockdown phenotypes and the changes in gene expression. Our results indicate that NHR-23 is a critical coregulator of functionally linked genes involved in growth and molting and reveal evolutionary parallels among the ecdysozoa.
NHR-23 dependent collagen and hedgehog-related genes required for molting.
Specimen part
View SamplesThe biology of chronic myeloid leukemia (CML)-stem cells is still incompletely understood. Therefore, we previously developed an inducible transgenic mouse model in which stem cell targeted induction of BCR-ABL expression leads to chronic phase CML-like disease. Here, we now demonstrate that the disease is transplantable using BCR-ABL positive LSK cells (lin-Sca-1+c-kit+). Interestingly, the phenotype is enhanced when unfractionated bone marrow (BM) cells are transplanted. However, neither progenitor cells (lin-Sca-1-c-kit+) nor mature granulocytes (CD11b+Gr-1+), or potential stem cell niche cells were able to transmit the disease or alter the phenotype. The phenotype was largely independent of BCR ABL priming prior to transplant. However, BCR-ABL abrogated the potential of LSK cells to induce full blown disease in secondary recipients. Subsequently, we found that BCR-ABL increased the fraction of multipotent progenitor cells (MPP) at the expense of long term HSC (LT-HSC) in the BM. Microarray analyses of LSK cells revealed that BCR-ABL alters the expression of genes involved in proliferation, survival, and hematopoietic development. Our results suggest that BCR-ABL induces differentiation of LT-HSC and decreases their self renewal capacity. Furthermore, reversion of BCR-ABL eradicates mature cells while leukemic stem cells persist, giving rise to relapsed CML upon re-induction of BCR-ABL.
BCR-ABL enhances differentiation of long-term repopulating hematopoietic stem cells.
Specimen part
View SamplesPolycomb group (PcG) proteins play a pivotal role in silencing developmental genes and help to maintain various stem and precursor cells and regulate their differentiation. PcG factors also regulate dynamic and complex regional specification, particularly in mammals, but this activity is mechanistically not well understood. In this study, we focused on proximal-distal (PD) patterning of the mouse forelimb bud to elucidate how PcG factors contribute to a regional specification process that depends on developmental signals. Depletion of the RING1 proteins RING1A (RING1) and RING1B (RNF2), which are essential components of Polycomb repressive complex 1 (PRC1), led to severe defects in forelimb formation along the PD axis. We show that preferential defects in early distal specification in Ring1A/B-deficient forelimb buds accompany failures in the repression of proximal signal circuitry bound by RING1B, including Meis1/2, and the activation of distal signal circuitry in the prospective distal region. Additional deletion of Meis2 induced partial restoration of the distal gene expression and limb formation seen in the Ring1A/B-deficient mice, suggesting a crucial role for RING1-dependent repression of Meis2 and likely also Meis1 for distal specification. We suggest that the RING1-MEIS1/2 axis is regulated by early PD signals and contributes to the initiation or maintenance of the distal signal circuitry.
RING1 proteins contribute to early proximal-distal specification of the forelimb bud by restricting Meis2 expression.
Specimen part
View SamplesPolycomb group (PcG) proteins play a pivotal role in silencing of development-related genes and contribute to maintain various stem and precursor cells and regulate their differentiation. However, it is not well understood how PcG factors regulate dynamic and complex morphogenetic processes particularly in mammals. In this study, we focused on proximal-distal (PD) patterning of forelimb bud to elucidate how PcG factors contribute to regulation of morphogenetic processes that depends on developmental signals. Depletion of RING1 proteins, which are common components of both canonical and variant Polycomb repressive complex-1 (PRC1), led to dramatic deficiencies in forelimb formation.
RING1 proteins contribute to early proximal-distal specification of the forelimb bud by restricting Meis2 expression.
Specimen part
View SamplesSome of the functions and mechanisms of PPAR?-mediated regulation of vascular homeostasis have been revealed, the potential role of PPAR? in angiogenesis is obscure. In human ECs, PPAR?-deficiency was studied using siRNA strategy and RNA sequencing was utilized to reveal angiogenesis-associated targets for PPARg. Overall design: Our aim is to reveal the possible role of PPARy in angiogenesis.
Loss of PPARγ in endothelial cells leads to impaired angiogenesis.
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View SamplesUsing wild type and Ash1l deltaSET mutant embryonic stem cells, here we report differences of gene expression pattern under undifferentiated state and differentiated state. Interestingly, gene expression changes are frequently observed in a subset of gene group that is regulated by Polycomb group proteins. Overall design: Examination of 2 cell types in 2 different conditions.
Ash1l methylates Lys36 of histone H3 independently of transcriptional elongation to counteract polycomb silencing.
Cell line, Treatment, Subject
View SamplesIDH1-R132H is expressed in Low Grade Glioma (LGG) in combination with loss of function mutation in ATRX and TP53 genes. IDH1-R132H results in gain of function with production of 2-hydroxygluatrate, that in turn generates a hypermethylatyed phenotype in DNA and histone with consequences in epigenetic regulation of gene expression. Here we will compare the gene expression profile between IDH1-R132H and IDH1 Wt LLG animal brain tumors in reponse to radiation Overall design: Evaluate differential gene expression between Brain DH1-R132H and IDH1 wt in response to 10Gy ionizing radiation at 14 days after tumor neurospheres implantation
IDH1-R132H acts as a tumor suppressor in glioma via epigenetic up-regulation of the DNA damage response.
Specimen part, Treatment, Subject
View SamplesProtein deficiency and intestinal parasite infection during pregnancy impair fetal growth through passage of signals from the maternal environment which signal impairment of fetal growth. The placenta is an important regulator of the transfer of these signals through differential expression of key placental genes. We used microarrays to examine placental gene expression responses to maternal protein deficiency (6% vs. 24% protein) and Heligmosomoides bakeri infection.
Expression of growth-related genes in the mouse placenta is influenced by interactions between intestinal nematode (Heligmosomoides bakeri) infection and dietary protein deficiency.
Specimen part
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