Immunoglobulin molecular genetics: the prospects for mutational analysis of the chromosomal immunoglobulin genes

Genome ◽  
1989 ◽  
Vol 31 (1) ◽  
pp. 175-181 ◽  
Author(s):  
Marc J. Shulman ◽  
Lucine Bosnoyan ◽  
Catherine Collins ◽  
Nancy Pennell ◽  
Mark D. Baker
Keyword(s):  
Gene Expression ◽  
Homologous Recombination ◽  
Mutational Analysis ◽  
Regulatory Elements ◽  
Hybridoma Cells ◽  
Immunoglobulin Genes ◽  
Chromosomal Dna ◽  
Cis Acting ◽  
Chromosomal Genes ◽  
Recombination Gene

Homologous recombination between transferred and chromosomal DNA can be used to effect precise, predetermined modifications of the chromosomal genes. Ultimately this phenomenon should allow the assessment of genetic regulatory elements as they function in the normal chromosomal environment. We have previously described a system for isolating mutant hybridoma cells that are defective in immunoglobulin (Ig) production, with a view toward using these mutants to define cis-acting elements that influence Ig gene expression. Here we describe results that indicate that homologous recombination between transferred and chromosomal Ig genes can be used to map Ig mutations by marker rescue.Key words: homologous recombination, gene expression.

scholarly journals CFTR Cooperative Cis-Regulatory Elements in Intestinal Cells

2021 ◽  
Vol 22 (5) ◽  
pp. 2599
Author(s):  
Mégane Collobert ◽  
Ozvan Bocher ◽  
Anaïs Le Nabec ◽  
Emmanuelle Génin ◽  
Claude Férec ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cystic Fibrosis ◽  
Gene Regulation ◽  
Genetic Diseases ◽  
Regulatory Elements ◽  
Cftr Gene ◽  
Intestinal Cells ◽  
Cooperative Effects ◽  
Cis Acting ◽  
Study Techniques

About 8% of the human genome is covered with candidate cis-regulatory elements (cCREs). Disruptions of CREs, described as “cis-ruptions” have been identified as being involved in various genetic diseases. Thanks to the development of chromatin conformation study techniques, several long-range cystic fibrosis transmembrane conductance regulator (CFTR) regulatory elements were identified, but the regulatory mechanisms of the CFTR gene have yet to be fully elucidated. The aim of this work is to improve our knowledge of the CFTR gene regulation, and to identity factors that could impact the CFTR gene expression, and potentially account for the variability of the clinical presentation of cystic fibrosis as well as CFTR-related disorders. Here, we apply the robust GWAS3D score to determine which of the CFTR introns could be involved in gene regulation. This approach highlights four particular CFTR introns of interest. Using reporter gene constructs in intestinal cells, we show that two new introns display strong cooperative effects in intestinal cells. Chromatin immunoprecipitation analyses further demonstrate fixation of transcription factors network. These results provide new insights into our understanding of the CFTR gene regulation and allow us to suggest a 3D CFTR locus structure in intestinal cells. A better understand of regulation mechanisms of the CFTR gene could elucidate cases of patients where the phenotype is not yet explained by the genotype. This would thus help in better diagnosis and therefore better management. These cis-acting regions may be a therapeutic challenge that could lead to the development of specific molecules capable of modulating gene expression in the future.

Analysis of a tissue-specific enhancer: ARF6 regulates adipogenic gene expression

1992 ◽  
Vol 12 (3) ◽  
pp. 1202-1208
Author(s):  
R A Graves ◽  
P Tontonoz ◽  
B M Spiegelman
Keyword(s):  
Gene Expression ◽  
Cultured Cells ◽  
Mutational Analysis ◽  
Cell Types ◽  
Specific Gene ◽  
Enhancer Activity ◽  
Cis Acting ◽  
Specific Gene Expression ◽  
Nuclear Extracts ◽  
Adipogenic Gene

The molecular basis of adipocyte-specific gene expression is not well understood. We have previously identified a 518-bp enhancer from the adipocyte P2 gene that stimulates adipose-specific gene expression in both cultured cells and transgenic mice. In this analysis of the enhancer, we have defined and characterized a 122-bp DNA fragment that directs differentiation-dependent gene expression in cultured preadipocytes and adipocytes. Several cis-acting elements have been identified and shown by mutational analysis to be important for full enhancer activity. One pair of sequences, ARE2 and ARE4, binds a nuclear factor (ARF2) present in extracts derived from many cell types. Multiple copies of these elements stimulate gene expression from a minimal promoter in preadipocytes, adipocytes, and several other cultured cell lines. A second pair of elements, ARE6 and ARE7, binds a separate factor (ARF6) that is detected only in nuclear extracts derived from adipocytes. The ability of multimers of ARE6 or ARE7 to stimulate promoter activity is strictly adipocyte specific. Mutations in the ARE6 sequence greatly reduce the activity of the 518-bp enhancer. These data demonstrate that several cis- and trans-acting components contribute to the activity of the adipocyte P2 enhancer and suggest that ARF6, a novel differentiation-dependent factor, may be a key regulator of adipogenic gene expression.

scholarly journals Homologous recombination in hybridoma cells: dependence on time and fragment length.

1990 ◽  
Vol 10 (9) ◽  
pp. 4466-4472 ◽  
Author(s):  
M J Shulman ◽  
L Nissen ◽  
C Collins
Keyword(s):  
Gene Expression ◽  
Homologous Recombination ◽  
Fragment Length ◽  
Myeloma Cell ◽  
Dna Transfer ◽  
Hybridoma Cells ◽  
Immunoglobulin Gene ◽  
Wild Type ◽  
Immunoglobulin Production ◽  
Available Technology

Mutant hybridoma-myeloma cell lines that are defective in immunoglobulin production are expected to be useful for defining the molecular requirements of immunoglobulin gene expression. The analysis of such mutants would be greatly facilitated if they could be mapped by marker rescue, i.e., by identifying the segments of wild-type DNA that can restore the normal phenotype by homologous recombination with the mutant chromosomal immunoglobulin gene. To assess the feasibility of this type of mapping, we have measured the efficiency with which fragments of wild-type DNA recombine with a mutant hybridoma immunoglobulin gene and restore normal immunoglobulin production. We found that most if not all recombinants were detectable 2 days after DNA transfer and that the frequency of gene restoration increased with increasing length of the transferred mu gene fragments, between 1.2 and 9.5 kilobases. These results indicate that the available technology should be adequate to map mutations in the mu gene to within approximately 1 kilobase.

Factors Involved in the Regulation of Type I Collagen Gene Expression: Implication in Fibrosis

2002 ◽  
Vol 227 (5) ◽  
pp. 301-314 ◽  
Author(s):  
Asish K. Ghosh
Keyword(s):  
Gene Expression ◽  
Collagen Synthesis ◽  
Molecular Mechanisms ◽  
Type I Collagen ◽  
Regulatory Elements ◽  
Transcriptional Level ◽  
Type I ◽  
Collagen Gene ◽  
Cis Acting ◽  
Collagen Gene Expression

Type I collagen, the major component of extracellular matrix in skin and other tissues, is a heterotrimer of two α1 and one α2 collagen polypeptides. The synthesis of both chains is highly regulated by different cytokines at the transcriptional level. Excessive synthesis and deposition of collagen in the dermal region causes thick and hard skin, a clinical manifestation of scleroderma. To better understand the causes of scleroderma or other tissue fibrosis, it is very Important to investigate the molecular mechanisms that cause upregulation of the Type I collagen synthesis in these tissues. Several cis-acting regulatory elements and trans-acting protein factors, which are involved in basal as well as cytokine-modulated Type I collagen gene expression, have been identified and characterized. Hypertranscription of Type I collagen in scleroderma skin fibroblasts may be due to abnormal activities of different positive or negative transcription factors In response to different abnormally induced signaling pathways. In this review, I discuss the present day understanding about the involvement of different factors in the regulation of basal as well as cytokine-modulated Type I collagen gene expression and its implication in scleroderma research.

scholarly journals Analysis of (δβ)0 Thalassemia and HPFH Deletions Suggest a Hierarchy of Cis-Acting Elements Regulating Fetal Hemoglobin Gene Expression.

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 54-54 ◽  
Author(s):  
Heather L Edward ◽  
Tasha Morrison ◽  
Jacqueline N Milton ◽  
Hong-yuan Luo ◽  
Lance Davis ◽  
...  
Keyword(s):  
Gene Expression ◽  
Binding Site ◽  
Conflicts Of Interest ◽  
Globin Gene ◽  
Regression Tree ◽  
Fetal Hemoglobin ◽  
Regulatory Elements ◽  
Globin Genes ◽  
Cis Acting ◽  
Cart Analysis

Abstract Hereditary persistence of fetal hemoglobin (HPFH) and (δβ)0 thalassemia are caused by deletions within the β-globin gene (HBB) cluster that remove elements that affect the expression of the γ-globin genes (HBG2 and HBG1, or HBG). These deletions are of different lengths and have different 5’ and 3’ breakpoints. The phenotypes associated with heterozygous carriers of (δβ)0 thalassemia and HPFH deletions are differentiated by levels of 5-15% HbF distributed heterocellularly in the former and 15-30% HbF distributed pancellularly in the latter. We found a novel 588.6 kb deletion that removed both the 3.5 kb fragment 5’ to HBD that is deleted in Corfu β thalassemia and contains a BCL11A binding site, and the known cis-acting elements downstream of HBB. The proband with this deletion had a HbF of 5.4% (Morrison et al, Blood, 2014 abstract 3452). To study the relative importance of 5’ and 3’ regulatory elements in HBG expression we studied 209 cases culled from the literature and from our laboratory where the 3.5 kb element 5’ to HBD and enhancers 3’ to HBB were deleted and HBG remained intact. We used a backwards stepwise regression statistical analysis to determine which deleted elements had the greatest effect on HbF levels. The combination of the deletion of 3.5 kb intergenic region 5’ to HBD, the presence of the HPFH-1 “3D” enhancer juxtaposed to HBG, and the deletion of the 3’ HS1 region accounted for 66.7% of the HbF variation in heterozygotes for HPFH and (δβ)0-thalassemia deletions. The HPFH-1 “3D” enhancer juxtaposed to HBG— the main difference between HPFH-1 and 2 compared with Spanish (δβ)0-thalassemia—was associated with an increase in HbF of 20.78% (p<2e-16) after adjusting for the effects of the other 5’ and 3’ cis-acting elements. The next most significant factor was the deletion of the 3.5 kb fragment 5’ to HBD which resulted in an increase of 10.62% HbF after similar adjustments (p<2e-16); deletion of the 3’ HS1 region accounted for an increase in HbF of 5.25% (p<1.05e-5). The HPFH-3 and HPFH-6 enhancer regions each accounted for a less than 1% increase in HbF and were not significantly associated with HbF in this model. Among 194 individuals where both 5’ and some 3’ elements affecting γ-globin gene expression—excluding the “3D” enhancer—were deleted, HbF was 20±9.3%; in 13 cases where all 3’ enhancers—including the “3D” enhancer—were deleted, HbF was 6.8±3.7% (p=8.9e-07). To determine which combinations of cis-acting elements were associated with high and low HbF levels we performed a classification and regression tree (cART) analysis on HbF. The results of the regression tree (Figure) only included the deletion of the 5’ 3.5 kb fragment region, the presence of the HPFH-1 “3D” enhancer and the deletion of the 3’ HS1 region and were consistent with the results of the backwards selection model. The absence of the 5’ 3.5 kb fragment 5’ to HBD combined with the presence of the HPFH-1 “3D” enhancer was associated with the highest average HbF of 27.02%. The absence of the 3.5 kb fragment 5’ to HBD combined with the absence of the HPFH-1 “3D” enhancer was associated with the lowest average HbF of 6.82%.The 588.6 kb deletion is the largest deletion reported in the HBB cluster that leaves the γ-globin genes intact, and the second to remove both the BCL11A binding site and all known 3’ enhancer elements. By studying deletions in the HBBgene cluster we have further defined the hierarchy of cis-acting elements that modulate HbF levels in adults and suggest a paramount role of the distal “3D” enhancer. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Homologous recombination in hybridoma cells: dependence on time and fragment length

1990 ◽  
Vol 10 (9) ◽  
pp. 4466-4472
Author(s):  
M J Shulman ◽  
L Nissen ◽  
C Collins
Keyword(s):  
Gene Expression ◽  
Homologous Recombination ◽  
Fragment Length ◽  
Myeloma Cell ◽  
Dna Transfer ◽  
Hybridoma Cells ◽  
Immunoglobulin Gene ◽  
Wild Type ◽  
Immunoglobulin Production ◽  
Available Technology

Mutant hybridoma-myeloma cell lines that are defective in immunoglobulin production are expected to be useful for defining the molecular requirements of immunoglobulin gene expression. The analysis of such mutants would be greatly facilitated if they could be mapped by marker rescue, i.e., by identifying the segments of wild-type DNA that can restore the normal phenotype by homologous recombination with the mutant chromosomal immunoglobulin gene. To assess the feasibility of this type of mapping, we have measured the efficiency with which fragments of wild-type DNA recombine with a mutant hybridoma immunoglobulin gene and restore normal immunoglobulin production. We found that most if not all recombinants were detectable 2 days after DNA transfer and that the frequency of gene restoration increased with increasing length of the transferred mu gene fragments, between 1.2 and 9.5 kilobases. These results indicate that the available technology should be adequate to map mutations in the mu gene to within approximately 1 kilobase.

scholarly journals Homologous recombination between transferred and chromosomal immunoglobulin kappa genes.

1988 ◽  
Vol 8 (10) ◽  
pp. 4041-4047 ◽  
Author(s):  
M D Baker ◽  
M J Shulman
Keyword(s):  
Homologous Recombination ◽  
Gene Mutations ◽  
Test System ◽  
Immunoglobulin M ◽  
Hybridoma Cells ◽  
Immunoglobulin Gene ◽  
Immunoglobulin Kappa ◽  
Chain Analysis ◽  
Chromosomal Genes ◽  
Specific Immunoglobulin

Homologous recombination between transferred and chromosomal DNAs provides a means of introducing well-defined, predetermined changes in the chromosomal genes. Here we report that this approach can be used to specifically modify the immunoglobulin genes in mouse hybridoma cells. The test system is based on the Sp6 hybridoma, which synthesizes immunoglobulin M (kappa) specific for the hapten 2,4,6-trinitrophenyl (TNP). As recipient cells, we used the Sp6-derived mutant hybridoma igk14, which has a deletion of the kappa TNP gene and consequently does not synthesize TNP-specific immunoglobulin M. igk14 retains the mu TNP gene and two additional rearranged kappa genes, denoted kappa M21B1 and kappa M21G. As a transfer vector, we used pSV2neo bearing the functionally rearranged TNP-specific V kappa segment. Following DNA transfer by electroporation, we isolated rare transformants which produced normal amounts of the functional kappa TNP chain. Analysis of the DNA of these transformants indicated that in all cases, a functional kappa TNP gene had been formed as the result of a homologous integrative recombination event with the igk14 kappa M21B1 gene. These results suggest that homologous recombination might be used for mapping and introducing immunoglobulin gene mutations and for more conveniently engineering specifically altered immunoglobulins.

scholarly journals uORFs: Important Cis-Regulatory Elements in Plants

2020 ◽  
Vol 21 (17) ◽  
pp. 6238
Author(s):  
Ting Zhang ◽  
Anqi Wu ◽  
Yaping Yue ◽  
Yu Zhao
Keyword(s):  
Gene Expression ◽  
Translation Initiation ◽  
Translational Control ◽  
Translational Regulation ◽  
Regulatory Elements ◽  
Ribosome Profiling ◽  
Open Reading Frames ◽  
Post Translational Modification ◽  
Cis Acting ◽  
Eukaryotic Mrnas

Gene expression is regulated at many levels, including mRNA transcription, translation, and post-translational modification. Compared with transcriptional regulation, mRNA translational control is a more critical step in gene expression and allows for more rapid changes of encoded protein concentrations in cells. Translation is highly regulated by complex interactions between cis-acting elements and trans-acting factors. Initiation is not only the first phase of translation, but also the core of translational regulation, because it limits the rate of protein synthesis. As potent cis-regulatory elements in eukaryotic mRNAs, upstream open reading frames (uORFs) generally inhibit the translation initiation of downstream major ORFs (mORFs) through ribosome stalling. During the past few years, with the development of RNA-seq and ribosome profiling, functional uORFs have been identified and characterized in many organisms. Here, we review uORF identification, uORF classification, and uORF-mediated translation initiation. More importantly, we summarize the translational regulation of uORFs in plant metabolic pathways, morphogenesis, disease resistance, and nutrient absorption, which open up an avenue for precisely modulating the plant growth and development, as well as environmental adaption. Additionally, we also discuss prospective applications of uORFs in plant breeding.

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