The Promoter of the Gene Encoding the C 4 Form of Phosphoenolpyruvate Carboxylase Directs Mesophyll-Specific Expression in Transgenic C 4 Flaveria spp

1997 ◽  
Vol 9 (4) ◽  
pp. 479 ◽  
Author(s):  
Jorg Stockhaus ◽  
Ute Schlue ◽  
Maria Koczor ◽  
Julie A. Chitty ◽  
William C. Taylor ◽  
...  
1997 ◽  
Vol 24 (4) ◽  
pp. 429 ◽  
Author(s):  
Peter Westhoff ◽  
Per Svensson ◽  
Karin Ernst ◽  
Oliver Bläsing ◽  
Janet Burscheidt ◽  
...  

C4 plants are known to be of polyphyletic origin and have evolved independently several times during the evolution of angiosperms. We are interested in understanding the molecular changes that the C4 genes have undergone as they were adapted to their new functions in C4 photosynthesis and are using the C4 phosphoenolpyruvate carboxylase (PEPC) of the genus Flaveria as a model. The PEPCs of F. trinervia (C4) and F. pringlei (C3) are encoded by a gene family that is composed of at least three different gene classes named ppcA, ppcB and ppcC. The C4 PEPC of F. trinervia is encoded by the ppcA gene class and is expressed at high levels only in the mesophyll cells of the leaves. The nearest neighbour to the ppcA gene class of F. trinervia is found in F. pringlei. Comparisons of this pair of orthologous gene classes are used to identify the C4 -specific differences between the enzymatic properties of the ppcA PEPCs and the activities of the ppcA promoters. The two ppcA PEPCs are 96% identical, but differ in the Km for phosphoenolpyruvate (PEP) and their inhibition by malate. Chimerical PEPCs are presently constructed to map the differences in the enzymatic properties of the C4 and C3 PEPC isoforms. To investigate determinants for the C4 specific expression pattern, the 5´ flanking regions of the ppcA1 genes of F. trinervia and F. pringlei were fused to the uidA reporter gene encoding ß-glucuronidase and transformed into the C4 plant F. bidentis and the C3 species tobacco. In F. bidentis, the C4ppcA1 promoter drives a high level of expression of the transgene only in the mesophyll cells, while the C3ppcA1 promoter leads to low levels of expression in leaves, stems and roots. Determinants for the C4 specific expression of the ppcA1 gene of F. trinervia must therefore be located in the 5´-flanking region of this gene. Further analyses showed that two regions, a proximal and a distal segment, are sufficient to generate the C4 specific expression pattern. In tobacco, the C4ppcA1 promoter is preferentially expressed in the palisade parenchyma cells of the leaves. These results indicate that the major events during the evolution of the C4ppcA promoter occurred at the promoter level.


Author(s):  
Giovanna Carrà ◽  
Giuseppe Ermondi ◽  
Chiara Riganti ◽  
Luisella Righi ◽  
Giulia Caron ◽  
...  

Abstract Background Oxidative stress is a hallmark of many cancers. The increment in reactive oxygen species (ROS), resulting from an increased mitochondrial respiration, is the major cause of oxidative stress. Cell fate is known to be intricately linked to the amount of ROS produced. The direct generation of ROS is also one of the mechanisms exploited by common anticancer therapies, such as chemotherapy. Methods We assessed the role of NFKBIA with various approaches, including in silico analyses, RNA-silencing and xenotransplantation. Western blot analyses, immunohistochemistry and RT-qPCR were used to detect the expression of specific proteins and genes. Immunoprecipitation and pull-down experiments were used to evaluate protein-protein interactions. Results Here, by using an in silico approach, following the identification of NFKBIA (the gene encoding IκBα) amplification in various cancers, we described an inverse correlation between IκBα, oxidative metabolism, and ROS production in lung cancer. Furthermore, we showed that novel IκBα targeting compounds combined with cisplatin treatment promote an increase in ROS beyond the tolerated threshold, thus causing death by oxytosis. Conclusions NFKBIA amplification and IκBα overexpression identify a unique cancer subtype associated with specific expression profile and metabolic signatures. Through p65-NFKB regulation, IκBα overexpression favors metabolic rewiring of cancer cells and distinct susceptibility to cisplatin. Lastly, we have developed a novel approach to disrupt IκBα/p65 interaction, restoring p65-mediated apoptotic responses to cisplatin due to mitochondria deregulation and ROS-production.


1985 ◽  
Vol 5 (6) ◽  
pp. 1295-1300
Author(s):  
Y Barra ◽  
K Tanaka ◽  
K J Isselbacher ◽  
G Khoury ◽  
G Jay

The identification of a unique major histocompatibility complex class I gene, designated Q10, which encodes a secreted rather than a cell surface antigen has led to questions regarding its potential role in regulating immunological functions. Since the Q10 gene is specifically activated only in the liver, we sought to define the molecular mechanisms which control its expression in a tissue-specific fashion. Results obtained by transfection of the cloned Q10 gene, either in the absence or presence of a heterologous transcriptional enhancer, into a variety of cell types of different tissue derivations are consistent with the Q10 gene being regulated at two levels. The first is by a cis-dependent mechanism which appears to involve site-specific DNA methylation. The second is by a trans-acting mechanism which would include the possibility of an enhancer binding factor. The ability to efficiently express the Q10 gene in certain transfected cell lines offers an opportunity to obtain this secreted class I antigen in quantities sufficient for functional studies; this should also make it possible to define regulatory sequences which may be responsible for the tissue-specific expression of Q10.


2006 ◽  
Vol 11 (4) ◽  
pp. 410-421 ◽  
Author(s):  
S Davidson ◽  
K A Miller ◽  
A Dowell ◽  
A Gildea ◽  
A MacKenzie

Blood ◽  
2021 ◽  
Author(s):  
Roger Mulet-Lazaro ◽  
Stanley van Herk ◽  
Claudia A.J. Erpelinck ◽  
Eric Bindels ◽  
Mathijs Arnoud Sanders ◽  
...  

Transcriptional deregulation is a central event in the development of acute myeloid leukemia (AML). To identify potential disturbances in gene regulation, we conducted an unbiased screen of allele-specific expression (ASE) in 209 AML cases. The gene encoding GATA binding protein 2 (GATA2) displayed ASE more often than any other myeloid or cancer-related gene. GATA2 ASE was strongly associated with CEBPA double mutations (CEBPA DM), with 95% of cases presenting GATA2 ASE. In CEBPA DM AML with GATA2 mutations, the mutated allele was preferentially expressed. We found that GATA2 ASE is a somatic event lost in complete remission, supporting the notion that it plays a role in CEBPA DM AML. Acquisition of GATA2 ASE involved silencing of one allele via promoter methylation and concurrent overactivation of the other allele, thereby preserving expression levels. Notably, promoter methylation was also lost in remission together with GATA2 ASE. In summary, we propose that GATA2 ASE is acquired by epigenetic mechanisms and is a prerequisite for the development of AML with CEBPA DM. This finding constitutes a novel example of an epigenetic hit cooperating with a genetic hit in the pathogenesis of AML.


Sign in / Sign up

Export Citation Format

Share Document