The role of intron sequences in high level expression from CD45 cDNA constructs

Polymorphisms of IGF-IR gene and their association with economic traits in two indigenous Chinese dairy goat breeds

The insulin like growth factor 1 receptor (IGF-IR) plays an important role in regulating growth and development. To investigate the effects of IGF-IR polymorphisms on the economic traits of dairy goats, polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and DNA sequencing methods were used to screen single nucleotide polymorphisms (SNPs) within 9 IGF-IR fragments in Xinong Saanen dairy goat (XS, n = 268) and Guanzhong dairy goat (GZ, n = 440). Consequently, two SNPs, including NC_007319: g.26688 C>T (Leu 608 Leu) and NC_007319: g.28273 T>C within exon 9 and intron 10 were identified in R8 and R9 loci, respectively. At R8 locus, three genotypes were found, including CC, CT and TT, with genotypic frequencies of 0.11, 0.65 and, 0.24 respectively in XS goats, and 0.13, 0.78 and 0.09 in GZ goats; three genotypes which are C₁C₁, C₁T₁ and T₁T₁ were also found in R9 locus, with the genotypic frequencies of 0.48, 0.20 and 0.32 in XS goats, and 0.43, 0.22 and 0.35 in GZ goats, respectively. Based on χ² test, both XS and GZ populations were deviated from Hardy-Weinberg equilibrium at above two loci. The association analysis revealed that XS goats with CC genotype at R8 locus had heavier milk density than the CT ones (P < 0.05). At R9 locus, the body height of GZ goats with C₁C₁ and T₁T₁ genotypes was significantly higher than those with C₁T₁ genotype (P < 0.01 or P < 0.05). The individuals of GZ goat with C₁C₁ genotype had longer body length than those with T₁T₁ genotype (P < 0.05). The individuals of XS with T₁T₁ and C₁T₁ genotypes had higher body height than those with C₁C₁ genotype (P < 0.05). This study can provide theoretical and practical significances to improve the milk production traits and promote the growth and development in two Chinese indigenous dairy goat breeds.

A SNP (g.358A > T) at intronic region of CD9 molecule of crossbred bulls may associate with spermatozoal motility

The surface expression of CD9 (cluster-of-differentiation antigen-9) in sperms of certain mammalian species has been attributed to its fusion with the egg and thereby dictating the fertility of species. In the present study, we investigated the association of CD9 with crossbred bull sperm quality and quantity trait was analyzed using a total of 96 Frieswal (HF × Sahiwal) crossbred. A single nucleotide polymorphism (g.358A > T) in intron 6 was significantly associated with sperm concentration (P < 0.05) and motility percentage (P < 0.01). mRNA was extracted from good (progressive motility > 50%) and motility impaired (progressive motility < 50%) bull semen. The mRNA expression and seminal plasma protein concentration of CD9 was significantly (P < 0.05) higher among good quality bull semen than motility impaired ones. Our results thus may indicate that, mutation in the intronic region may be responsible for the instability of RNA and the subsequent functional protein expression.

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A single nucleotide polymorphism (g.358A > T) in intron 6 was significantly associated with sperm concentration.

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The mRNA expression and seminal plasma protein concentration of CD9 was significantly higher among good quality bull semen than motility impaired ones.

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Seminal plasma protein concentration of CD9 was higher in good quality semen.

Identification of hematopoietic-specific regulatory elements from the CD45 gene and use for lentiviral tracking of transplanted cells

The development of a hematopoietic reporter is crucial for determining the fate of lineages derived from cell-based therapies. A marking system will enable safer embryonic stem and induced pluripotent stem cell-based derivation of blood lineages and facilitate the development of efficient cellular reprogramming strategies based on direct fibroblast conversion. Here we report that the protein tyrosine phosphatase CD45 is an ideal candidate gene on which to base a hematopoietic reporter. CD45 regulatory elements were discovered by analyzing transcription factor chromatin occupancy (ChIP-seq) and promoter nuclease sensitivity (DNase-seq) to identify minimally sufficient sequences required for expression. After cloning the CD45 regulatory elements into an attenuated lentiviral backbone, we found that two transcriptional initiation regions were essential for high-level expression. Expressing CD45 promoters containing these regions and tethered to green fluorescent protein (GFP) in a primary B-cell differentiation assay and a transplantation model resulted in high levels of GFP in lymphoid, myeloid, and nucleated erythroid cells in mouse and human blood cell lineages. Moreover, GFP levels remained high 5 months after secondary transplantation, indicating persistence of the reporter. No CD45-driven GFP expression is observed after fibroblast or embryonic stem cell transduction. The GFP reporter is seen only after embryonic stem cells differentiate into hematopoietic cell progenitors and lineages, suggesting that this hematopoietic reporter system could be useful in validating potential autologous blood cell therapies.

Investigation into association and expression of PLCz and COX-2 as candidate genes for boar sperm quality and fertility

Phospholipase C zeta (PLCz) and cyclooxygenase isoenzyme type 2 (COX-2) are important in spermatogenesis, but their effect has not yet confirmed in pigs. Therefore, this study was aimed to analyse their association with sperm quality and fertility and to identify the mRNA and protein expression in boars reproductive tissues. DNA samples from 231 Pietrain (PI) and 109 Pietrain × Hampshire (PIHA) pigs with records of sperm quality [sperm concentration (SCON), motility, semen volume, plasma droplet and abnormal spermatozoa rate] and fertility (non-return rate and number of piglet born alive) traits were available. A SNP in non-coding region of PLCz g.158 A > C was associated with SCON (p < 0.05) in PIHA population while the polymorphism of COX-2 g.68 G > A in 3' UTR was not associated with any traits. For mRNA and protein expression study, a total of six boars were divided into two groups with G-I and G-II, where G-I was characterized for relatively better sperm quality. Both genes expressed higher in reproductive tissues compared with non-reproductive tissues. Phospholipase C zeta mRNA expressed higher in testis (p < 0.01), all parts of epididymis and spermatozoa from G-I, while COX-2 expressed higher in testis (p < 0.05), head and body of epididymis (p < 0.01), and spermatozoa from G-II boar. Both proteins were localized in Leydig cells and spermatozoa. These results might shed light on roles of these genes in spermatogenesis as candidate for boar sperm quality and fertility, but still the lack of association across populations should be considered.

Association study and expression analysis of CD9 as candidate gene for boar sperm quality and fertility traits

Cluster-of-differentiation antigen 9 (CD9) gene expressed in the male germ line stem cells is crucial for sperm-egg fusion, and was therefore selected as candidate gene for boar semen quality. The association of CD9 with boar sperm quality and fertility trait was analyzed using a total of 340 boars both from purebred Pietrain and Pietrain×Hampshire crosses. A single nucleotide polymorphism (g.358A>T) in intron 6 was significantly associated with sperm motility (MOT) (P<0.001), plasma droplet rate (PDR) (P<0.001) and abnormal spermatozoa rate (ASR) (P<0.01). Boars were divided into two groups with group 1 (G-I) boars having a higher SCON and SMOT, lower SVOL (sperm volume) and group 2 (G-II) having a lower SCON and SMOT, higher SVOL. The mRNA and protein expression levels were evaluated in reproductive, non-reproductive tissues and spermatozoa from G-I and G-II animals by using quantitative real-time PCR and western blotting. When both reproductive and non-reproductive tissues were examined, highest mRNA was expressed in prostate gland, then in the body of the epididymis, vas deferens and tail of the epididymis. In case of reproductive tissues, CD9 expression was higher in tissues and spermatozoa collected from G-I boars than those collected from G-II boars. The mRNA expression was significantly different (P<0.05) in body of epididymis from G-I and G-II boars. The CD9 protein expression results from western blot were coincided with the results of qRT-PCR. Moreover, CD9 protein localization in Leydig cells, Sertoli cells, epithelial cells and spermatozoa was remarkable which indicated the important role of CD9 in spermatogenesis process. By using mRNA and protein expression profiles, it could be shown that CD9 plays a crucial role during sperm development, especially within the epididymis where the maturation of the sperm, a key process for the sperm quality and motility takes place. These results will improve the understanding of the functions of the CD9 in spermatogenesis within the reproductive tracts and will shed light on CD9 as a candidate gene in the selection of good sperm quality boars.

Identification and functional characterisation of the promoter of the calcium sensor gene CBL1 from the xerophyte Ammopiptanthus mongolicus

BACKGROUND

CBL1 is a calcium sensor that regulates drought, cold and salt signals in Arabidopsis. Overexpression of CBL1 gene in Arabidopsis and in Ammopiptanthus mongolicus showed different tolerant activities. We are interested in understanding the molecular mechanism of the upstream region of the CBL1 gene of A. mongolicus (AmCBL1). We investigated and characterized the promoter of the AmCBL1 gene, for promoters play a very important role in regulating gene expression in eukaryotes.

RESULTS

A 1683-bp 5' flanking region was isolated from A. mongolicus. The sequence was identified as AmCBL1 promoter. Analysis of the promoter sequence indicated a 690-bp intron and some basic cis-acting elements were related to various environmental stresses and plant hormones. To identify the functional region of the AmCBL1 promoter, five plant expression vectors fused with the GUS (beta-glucuronidase) gene, driven by series deleted fragments of AmCBL1 promoter at different lengths from -1659, -1414, -1048, -296 to -167 bp relative to the transcriptional start site were constructed and transformed into Nicotiana tabacum L. cv. 89. Functional properties of each promoter segment were examined by GUS staining and fluorescence quantitative analyses using at least three single-copy PCR-positive plants of transgenic tobacco, treated with various environmental stresses and plant hormones for different times. We demonstrated that the AmCBL1 promoter was a vascular-specific and multiple-stress-inducible promoter. Our results further imply that the promoter fragment B1S3 possessed sufficient essential cis-acting elements, accounting for vascular-specific and stress-induced expression patterns. It may also indicate that for response to some stresses certain cis-elements are required in tissues outside the region of the B1S3 construct.

CONCLUSIONS

To help resolve uncertainties about the upstream regulatory mechanism of the CBL1 gene in desert plants, we suggest that the function of the AmCBL1 promoter, particularly under conditions of abiotic stress, to be examined for possible usefulness in molecular breeding. Regardless of the outcome, the allocation and relative quantification of the GUS-fusion AmCBL1 promoter segments at transcriptional levels in different tissues under various stresses across separate promoter segments suggests that the AmCBL1 promoter is a phloem-specific and multiple-stress-inducible promoter. These data coupled with the ongoing AmCBL1 5' UTR intron analyses provide a solid foundation for their future use in molecular breeding as new promoters of stress-resistance genes from desert plants.

Reduced expression of CD45 protein-tyrosine phosphatase provides protection against anthrax pathogenesis

The modulation of cellular processes by small molecule inhibitors, gene inactivation, or targeted knockdown strategies combined with phenotypic screens are powerful approaches to delineate complex cellular pathways and to identify key players involved in disease pathogenesis. Using chemical genetic screening, we tested a library of known phosphatase inhibitors and identified several compounds that protected Bacillus anthracis infected macrophages from cell death. The most potent compound was assayed against a panel of sixteen different phosphatases of which CD45 was found to be most sensitive to inhibition. Testing of a known CD45 inhibitor and antisense phosphorodiamidate morpholino oligomers targeting CD45 also protected B. anthracis-infected macrophages from cell death. However, reduced CD45 expression did not protect anthrax lethal toxin (LT) treated macrophages, suggesting that the pathogen and independently added LT may signal through distinct pathways. Subsequent, in vivo studies with both gene-targeted knockdown of CD45 and genetically engineered mice expressing reduced levels of CD45 resulted in protection of mice after infection with the virulent Ames B. anthracis. Intermediate levels of CD45 expression were critical for the protection, as mice expressing normal levels of CD45 or disrupted CD45 phosphatase activity or no CD45 all succumbed to this pathogen. Mechanism-based studies suggest that the protection provided by reduced CD45 levels results from regulated immune cell homeostasis that may diminish the impact of apoptosis during the infection. To date, this is the first report demonstrating that reduced levels of host phosphatase CD45 modulate anthrax pathogenesis.

Promoter-proximal introns in Arabidopsis thaliana are enriched in dispersed signals that elevate gene expression

Introns that elevate mRNA accumulation have been found in a wide range of eukaryotes. However, not all introns affect gene expression, and direct testing is currently the only way to identify stimulatory introns. Our genome-wide analysis in Arabidopsis thaliana revealed that promoter-proximal introns as a group are compositionally distinct from distal introns and that the degree to which an individual intron matches the promoter-proximal intron profile is a strong predictor of its ability to increase expression. We found that the sequences responsible for elevating expression are dispersed throughout an enhancing intron, as is a candidate motif that is overrepresented in first introns and whose occurrence in tested introns is proportional to its effect on expression. The signals responsible for intron-mediated enhancement are apparently conserved between Arabidopsis and rice (Oryza sativa) despite the large evolutionary distance separating these plants.

Differential lineage-specific regulation of murine CD45 transcription by Oct-1 and PU.1

Although it has been established that CD45 expression is regulated at the transcriptional level, neither the regulatory elements that are responsible for its unique expression pattern nor the relevance of its three distinct transcriptional start sites (P1a, P1b, and P2) has been fully characterized. We studied the contribution of the three start sites to CD45 mRNA production in haematopoietic cell lines and primary haematopoietic cells. In myeloid and lymphoid cells and cell lines most CD45 transcripts originate from P1b with the exception of the thymoma-derived T cell line EL4, in which approximately 90% of CD45 transcripts originate from P1a. The degree of contribution of P1a is highest in lymphoid cells and increases in T cells following mitogen stimulation. In vitro evaluation of sequence upstream of the start sites shows that the P2 start site is sufficient for CD45 expression in lymphoid but not in myeloid cells, confirms the presence of a PU.1-binding site essential for myeloid expression of CD45, and reveals an Octamer-binding site that interacts with both Oct-1 and Oct-2 and activates CD45 transcription in lymphoid and myeloid cells. These findings are the first evidence that Octamer-binding factors are involved in the control of CD45 expression.

Regulation of endothelial nitric oxide synthase by small RNA

Repeats (27-nt) in intron 4 have been shown to play a cis-acting role in endothelial nitric oxide synthase (eNOS) promoter activity. We hypothesize that the 27-nt repeats could be the source of small nuclear RNA specifically regulating eNOS expression. In this study, we used synthesized 27-nt RNA duplex and found that the eNOS gene transcriptional efficiency was reduced 63% (0.047 +/- 0.009 vs. 0.126 +/- 0.015, P < 0.01) by nuclear run-on assay. In endothelial cells transfected with the 27-nt small RNA duplex, we found that the eNOS mRNA and protein levels were decreased by >64% (P < 0.01). Conversely, a randomly selected 27-nt from luciferase gene had no effect on the eNOS expression. Furthermore, this eNOS silencing effect appeared to be reversible under the stimulation of vascular endothelial growth factor (10 ng/ml), which is known to up-regulate eNOS expression. Using in situ hybridization and Northern blotting, we observed the presence of endogenous eNOS intron 4-derived 27-nt small RNA, which was confined to the nucleus. In summary, we demonstrated that intron-based microRNAs in eNOS can induce significant gene specific transcriptional suppression, which could be an effective negative feedback regulator for gene expression.

CD45: a critical regulator of signaling thresholds in immune cells

Regulation of tyrosine phosphorylation is a critical control point for integration of environmental signals into cellular responses. This regulation is mediated by the reciprocal actions of protein tyrosine kinases and phosphatases. CD45, the first and prototypic receptor-like protein tyrosine phosphatase, is expressed on all nucleated hematopoietic cells and plays a central role in this process. Studies of CD45 mutant cell lines, CD45-deficient mice, and CD45-deficient humans initially demonstrated the essential role of CD45 in antigen receptor signal transduction and lymphocyte development. It is now known that CD45 also modulates signals emanating from integrin and cytokine receptors. Recent work has focused on regulation of CD45 expression and alternative splicing, isoform-specific differences in signal transduction, and regulation of phosphatase activity. From these studies, a model is emerging in which CD45 affects cellular responses by controlling the relative threshold of sensitivity to external stimuli. Perturbation of this function may contribute to autoimmunity, immunodeficiency, and malignancy. Moreover, recent advances suggest that modulation of CD45 function can have therapeutic benefit in many disease states.

Promoter analysis of the human SLC7A7 gene encoding y+L amino acid transporter-1 (y+LAT-1)

The human SLC7A7 gene on chromosome 14q11.2 encodes the y+L amino acid transporter-1 (y+LAT-1) protein that transports, together with the 4F2hc cell surface antigen, cationic amino acids through the basolateral membrane of epithelial cells in the small intestine and kidney. The SLC7A7 gene comprises 11 exons, but the first two are not translated. Mutations in the coding region of the SLC7A7 gene cause a rare autosomal disorder, lysinuric protein intolerance (LPI). We have now investigated the expression levels and putative 5' promoter elements of the SLC7A7. The 5' region of the first untranslated exon contains no TATA-box, Inr elements nor other classical promoter elements, but has instead other putative transcription factor binding sequences. The E-box and AP-2 elements were able to bind proteins in HEK293 cells and adult kidney tissue extracts, but not in fibroblasts. Using transient transfection and luciferase reporter gene studies, we showed that the first two introns located in the untranslated region contained transcriptional enhancer elements. Northern blot analysis showed low and equal SLC7A7 mRNA levels in the control and LPI patient fibroblastoid and lymphoblast cells.

A CD45 minigene restores regulated isoform expression and immune function in CD45-deficient mice: therapeutic implications for human CD45-null severe combined immunodeficiency

Transgenic mice have been generated that carry a CD45 minigene under control of the human leukocyte function-associated antigen (LFA-1, CD11a) promoter. CD45-null mice carrying the transgene exhibit the lymphocyte lineage-specific isoform expression patterns of wild-type mice. Furthermore, these mice have normal thymocyte development and peripheral T-cell numbers. The proliferative ability of T cells in response to mitogens and antigen also is regained, as is B-cell responsiveness to anti-IgM. The antibody response to antigen is also restored and is similar to that of normal mice. Therefore, introduction of a functional CD45 minigene is sufficient to overcome the principal severe combined immunodeficiency (SCID)-associated defects and represents a potential route to a gene therapy for human CD45-deficent SCID.