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Gene Switch (gene + switch)

Distribution by Scientific Domains

Life Sciences	75%

Selected Abstracts

Metabolic gene switching in the murine female heart parallels enhanced mitochondrial respiratory function in response to oxidative stress

FEBS JOURNAL, Issue 20 2007
M. Faadiel Essop
The mechanisms underlying increased cardioprotection in younger female mice are unclear. We hypothesized that serine-threonine protein kinase (protein kinase B; Akt) triggers a metabolic gene switch (decreased fatty acids, increased glucose) in female hearts to enhance mitochondrial bioenergetic capacity, conferring protection against oxidative stress. Here, we employed male and female control (db/+) and obese (db/db) mice. We found diminished transcript levels of peroxisome proliferator-activated receptor-alpha, muscle-type carnitine palmitoyltransferase 1 and pyruvate dehydrogenase kinase 4 in female control hearts versus male hearts. Moreover, females displayed improved recovery of cardiac mitochondrial respiratory function and higher ATP levels versus males in response to acute oxygen deprivation. All these changes were reversed in female db/db hearts. However, we found no significant gender-based differences in levels of Akt, suggesting that Akt-independent signaling mechanisms are responsible for the resilient mitochondrial phenotype observed in female mouse hearts. As glucose is a more energetically efficient fuel substrate when oxygen is limiting, this gene program may be a crucial component that enhances tolerance to oxygen deprivation in female hearts. [source]

Disorders of the synthesis of human fetal hemoglobin

IUBMB LIFE, Issue 2 2008
Laura Manca
Abstract Fetal hemoglobin (HbF), the predominant hemoglobin in the fetus, is a mixture of two molecular species (,2G,2 and ,2A,2) that differ only at position 136 reflecting the products of two nonallelic ,-globin genes. At the time of birth, HbF accounts for ,70% of the total Hb. The G,:A, globin ratio in the HbF of normal newborn is 70:30 whereas in the trace amounts of HbF that is found in the adult it reverses to 40:60 because of a ,- to ,-globin gene switch. Alterations of these ratios are indicative of a molecular defect at the level of the HbF synthesis. Qualitative hemoglobinopathies due to G, and A, chain structural variants, and quantitative hemoglobinopathies affecting the synthesis of HbF such as ,-thalassemias, duplications, triplications, and even sextuplications of the ,-globin genes, which may be detected in newborn blood lysates, have been described. Moreover, several pathological and nonpathological conditions affecting the ,-globin gene cluster, such as ,-thalassemia, sickle cell disease, ,,-thalassemia, and hereditary persistence of HbF syndromes, are characterized by the continued synthesis of ,-globin chains in the adult life. Studies of these natural mutants associated with increased synthesis of HbF in adult life have provided considerable insight into the understanding of the control of globin gene expression and Hb switching. © 2008 IUBMB IUBMB Life, 60(2): 94,111, 2008 [source]

Coupling the GAL4 UAS system with alcR for versatile cell type-specific chemically inducible gene expression in Arabidopsis

PLANT BIOTECHNOLOGY JOURNAL, Issue 4 2007
Lali Sakvarelidze
Summary The Aspergillus alc regulon encodes a transcription factor, ALCR, which regulates transcription from cognate promoters such as alcA(p). In the presence of suitable chemical inducers, ALCR activates gene expression from alcA(p). The alc regulon can be transferred to other species and can be used to control the expression of reporter, metabolic and developmental genes in response to low-level ethanol exposure. In this paper, we describe a versatile system for targeting the alc regulon to specific cell types in Arabidopsis by driving ALCR expression from the GAL4 upstream activator sequence (UAS). Large numbers of Arabidopsis lines are available in which GAL4 is expressed in a variety of spatial patterns and, in turn, drives the expression of any gene cloned downstream of the UAS. We have used a previously characterized line that directs gene expression to the endosperm to demonstrate spatially restricted ethanol-inducible gene expression. We also show that the domain of inducible gene expression can easily be altered by crossing the UAS::ALCR cassette into different driver lines. We conclude that this gene switch can be used to drive gene expression in a highly responsive, but spatially restricted, manner. [source]

Reversal of the silencing of tetracycline-controlled genes requires the coordinate action of distinctly acting transcription factors

THE JOURNAL OF GENE MEDICINE, Issue 1 2005
Renata Pankiewicz
Abstract Background Regulation of genes transferred to eukaryotic organisms is often limited by the lack of consistent expression levels in all transduced cells, which may result in part from epigenetic gene silencing effects. This reduces the efficacy of ligand-controlled gene switches designed for somatic gene transfers such as gene therapy. Methods A doxycycline-controlled transgene was stably introduced in human cells, and clones were screened for epigenetic silencing of the transgene. Various regulatory proteins were targeted to the silent transgene, to identify those that would mediate regulation by doxycycline. Results A doxycycline-controlled minimal promoter was found to be prone to gene silencing, which prevents activation by a fusion of the bacterial TetR DNA-binding domain with the VP16 activator. DNA modification studies indicated that the silenced transgene adopts a poorly accessible chromatin structure. Several cellular transcriptional activators were found to restore an accessible DNA structure when targeted to the silent transgene, and they cooperated with Tet-VP16 to mediate regulation by doxycycline. Conclusions Reversal of the silencing of a tetracycline-regulated minimal promoter requires a chromatin-remodeling activity for subsequent promoter activation by the Tet-VP16 fusion protein. Thus, distinct regulatory elements may be combined to obtain long-term regulation and persistent expression of exogenous genes in eukaryotic cells. Copyright © 2004 John Wiley & Sons, Ltd. [source]