Amount Of Gene Product Research Articles

MiRNAs as novel biomarkers for bone related diseases

MicroRNAs (miRNAs) are single stranded, non-coding RNAs that regulate mRNA expression and the amount of gene products. miRNAs regulate mRNA expression through direct binding and influence various signalling pathways in the organism. miRNAs have been found to play key roles in cell proliferation, differentiation, organ and tissue development and the regulation of bone homeostasis. They contribute to bone formation and resorption, bone remodelling and the differentiation of bone cells. Therefore, altered expression of distinct miRNAs may influence the pathology of bone diseases, such as osteoporosis, renal osteodystrophy and malignant bone tumours. miRNAs are released into the bloodstream, partly through active secretion, and are bound to structures, such as proteins and exosomes, that protect the miRNAs from degradation. Therefore, miRNAs are easy to sample, and they are stable with great potential as biomarkers for several diseases, including osteoporosis. This review is giving a short overview on the background and the features of the miRNAs and other non-coding RNAs, highlighting examples for their relevance in bone diseases and summarizing knowledge on miRNAs as biomarkers for osteoporosis.

Commentary: Unravelling the effects of additional sex chromosomes on cognition and communication – reflections on Lee et al. (2012)

Commentary: Unravelling the effects of additional sex chromosomes on cognition and communication – reflections on Lee et al. (2012)

Cell interactions and planar polarity in the abdominal epidermis of Drosophila.

The integument of the Drosophila adult abdomen bears oriented hairs and bristles that indicate the planar polarity of the epidermal cells. We study four polarity genes, frizzled (fz), prickle (pk), Van gogh/strabismus (Vang/stbm) and starry night/flamingo (stan/fmi), and note what happens when these genes are either removed or overexpressed in clones of cells. The edges of the clones are interfaces between cells that carry different amounts of gene products, interfaces that can cause reversals of planar polarity in the clone and wild-type cells outside them. To explain, we present a model that builds on our earlier picture of a gradient of X, the vector of which specifies planar polarity and depends on two cadherin proteins, Dachsous and Fat. We conjecture that the X gradient is read out, cell by cell, as a scalar value of Fz activity, and that Pk acts in this process, possibly to determine the sign of the Fz activity gradient. We discuss evidence that cells can compare their scalar readout of the level of X with that of their neighbours and can set their own readout towards an average of those. This averaging, when it occurs near the edges of clones, changes the scalar response of cells inside and outside the clones, leading to new vectors that change polarity. The results argue that Stan must be present in both cells being compared and acts as a conduit between them for the transfer of information. And also that Vang assists in the receipt of this information. The comparison between neighbours is crucial, because it gives the vector that orients hairs--these point towards the neighbour cell that has the lowest level of Fz activity. Recently, it has been shown that, for a limited period shortly before hair outgrowth in the wing, the four proteins we study, as well as others, become asymmetrically localised in the cell membrane, and this process is thought to be instrumental in the acquisition of cell polarity. However, some results do not fit with this view--we suggest that these localisations may be more a consequence than a cause of planar polarity.

Plant evolution: The dominance of maize

The gene teosinte branched 1 controls major differences in architecture between cultivated maize and its wild ancestor. The differences correlate with different amounts of gene product.

Stable Expression of the Sulphur-rich 2S Albumin Gene in Transgenic Vicia narbonensis Increases the Methionine Content of Seeds

Summary Both the narbon bean ( Vicia narbonensis ) and tobacco plants were transformed using Agrobacterium tumefaciens strains containing binary vectors with the gene coding for the methionine-rich 2S albumin of Brazil nuts under the control of either the Cauliflower Mosaic Virus 35S promoter or the legumin B4 promoter from V. faba . Stable integration in the genome was verified by both Southern blotting and segregation analysis. Under the control of the viral promoter, 2S albumin was produced in a variety of tissues at a relatively low level in both species. The LeB4 promoter conferred seed-specific high level expression in V. narbonensis and low level seed-specific expression in tobacco. A total of 50 independent transgenic narbon bean lines containing the LeB4-2S albumin construct have so far been isolated. Eighteen of these lines were further characterised and several stable homozygous lines established. Comparisons of homozygous and heterozygous progeny in these strains revealed that a doubling of the number of genes resulted in an approximate doubling in the amount of gene product. The absolute protein levels reached varied between lines. Amino acid analysis revealed an approximate 3 fold increase in the methionine content of seed protein in one R 0 line. Further analysis of these lines is aimed at determining how to achieve high level production of foreign proteins in seeds and more specifically at improving the nutritional quality of the seed protein of legumes.

Prospects for human gene therapy.

The introduction of the adenosine deaminase (ADA) gene into mature lymphocytes of a patient with ADA deficiency offers only a temporary treatment of the immunodeficiency but has paved the way for potential cure of this and other inherited diseases through the use of somatic gene therapy. Rapid progress in the development of molecular technology has resulted in the identification of a number of disease genes, the subsequent cloning of their normal counterparts, and has enabled scientists to address correction of these inherited disorders. Large amounts of gene products can now be produced by recombinant technology and initial therapeutic efforts focused on the in vivo administration of such purified recombinant proteins. This therapeutic approach has been ineffective in the treatment of genetic diseases in which the activity of the enzyme is located within the cell, with the notable exceptions of ADA deficiency and Gaucher disease (1). Even when addition of the deficient enzyme has been found to correct the biochemical defect in vitro, in vivo administration of the enzyme has generally not proven to be adequate therapy for correction of the defect due to either accelerated metabolism of the protein or an enhanced immune response to the protein. Research efforts in the correction of inherited defects have thus been directed to the transfer of normal genes to autologous target cells and the reintroduction of these cells into the patient. The use of various strategies to transfer genetic sequences into somatic cells from patients and their readministration to the patient for clinical benefits constitutes somatic gene therapy (2). The requirements for a successful gene therapy protocol include: (i) identification and availability of the defective gene (cloned) (ii) knowledge of the biology and regulation of the gene in the target tissue and (iii) the ability to transduce sufficient numbers of target cells as well as ensuring proper gene regulation. Although most commonly considered in the context of inherited single gene defects because of the extensive molecular knowledge of the defective gene and target cell involved, gene therapy plays an increasingly greater role in the therapy of acquired diseases, as the genes and target cells involved in these disorders are identified and new methods of gene transfer are developed.

A poxvirus-derived vector that directs high levels of expression of cloned genes in mammalian cells.

High levels of expression of cloned genes have been obtained in mammalian cells by using poxvirus-derived insertion/expression vectors. These vectors employ the cis-acting element (CAE I) that directs the transcription of one of the most strongly expressed genes of cowpox virus. This gene (the 160K gene) encodes the 160-kDa protein that is the major component of the A-type cytoplasmic inclusions. Its counterpart in vaccinia virus (VV) is the 94K gene contained in the HindIII A fragment of the viral DNA. Two insertion vectors have been constructed; each is designed to allow cloned genes to be placed immediately downstream of a modified version of CAE I within a poxvirus genome. One vector, p1200, enables the CAE I-cloned-gene constructs to be inserted into the thymidine kinase gene of VV. This vector was used to create a VV recombinant that directed expression of the chloramphenicol acetyltransferase (CAT) gene. The other vector, p2101, enables the CAE I-cloned-gene constructs to be inserted into the VV 94K gene. The prototype of this vector was used to create a VV recombinant that directed expression of a hybrid CAT-lacZ gene. Infection of cultured human cells with these recombinants led to high levels of synthesis of either the CAT gene product or the CAT-lacZ gene product. Each of these proteins was produced in quantities that were easily detected by Coomassie blue staining of total cell proteins resolved by polyacrylamide gel electrophoresis. We estimate that these vectors are capable of directing the synthesis of milligram amounts of gene product per 10(9) mammalian cells.

Translation of a synthetic two-cistron mRNA in Escherichia coli.

A synthetic two-cistron expression system was constructed for the high-level expression of eukaryotic genes in Escherichia coli. This system was designed to overcome translational inhibition of mRNAs containing eukaryotic sequences. The first cistron in this system is a 31-base A + T-rich synthetic sequence that provides for efficient translation initiation. The second cistron contains the protein coding sequence for the eukaryotic gene. Insertion of the first cistron between the 5' untranslated region of the mRNA and the protein coding region separates the two and thereby potentially minimizes the formation of local secondary structures that might prevent ribosomes from binding and initiating translation. The 31-base cistron contains three nonsense codons (TAA), one in each of the three translational reading frames, and an 8-base Shine-Dalgarno sequence that is complementary to the 3' end of the 16S rRNA. The effects of translation of the first cistron in all three reading frames on the expression of the second cistron was examined. The most efficient expression of the second cistron seemed to occur when the stop codon that terminates translation of the first cistron is located 3' to the Shine-Dalgarno sequence and close to the AUG start codon for the second cistron. When the Shine-Dalgarno sequence was deleted from the first cistron, no detectable expression of the second cistron was observed. This two-cistron system has been used to express the gene encoding methionylalanyl bovine growth hormone with its native codons and the gene encoding methionyl human growth hormone at a level greater than 20% of total cell protein. In the case of human growth hormone, we show that the amount of gene product is not significantly diminished by placing a "functional" first cistron in front of a gene that can be expressed without a cistron.