Linking CREB function with altered metabolism in murine fibroblast-based model cell lines

Abstract

The cAMP-responsive element binding protein CREB is frequently overexpressed and activated in tumors of distinct histology, leading to enhanced proliferation, migration, invasion and angiogenesis as well as reduced apoptosis. The de-regulated expression of CREB might be linked with transcriptional as well as post-transcriptional regulation mechanisms. We show here that altered CREB expression levels and function are associated with changes in the cellular metabolism. Using comparative proteome-based analysis an altered expression pattern of proteins involved in the cellular metabolism in particular in glycolysis was found upon CREB down-regulation in HER-2/neu-transfected cell lines. This was associated with diminished expression levels of the glucose transporter 1, reduced glucose uptake and reduced glycolytic activity in HER-2/neu-transfected cells with down-regulated CREB when compared to HER-2/neu+ cells. Furthermore, hypoxia-induced CREB activity resulted in changes of the metabolism in HER-2/neu transfected cells. Low pH values in the supernatant of HER-2/neu transformants were restored by CREB down-regulation, but further decreased by hypoxia. The altered intracellular pH values were associated with a distinct expression of lactate dehydrogenase, and its substrate lactate. Moreover, enhanced phosphorylation of CREB on residue Ser133 was accompanied by a down-regulation of pERK and an up-regulation of pAKT. CREB promotes the detoxification of ROS by catalase, therefore protecting the mitochondrial activity under oxidative stress. These data suggest that there might exists a link between CREB function and the altered metabolism in HER-2/neu-transformed cells. Thus, targeting these altered metabolic pathways might represent an attractive therapeutic approach at least for the treatment of patients with HER-2/neu overexpressing tumors.

Glucose Availability Alters Gene and Protein Expression of Several Newly Classified and Putative Solute Carriers in Mice Cortex Cell Culture and D. melanogaster

“…Atf4 (Averous et al, 2004;Dey et al, 2012) binding sites was present within the 1000 bp upstream of TSS for 69% of the sequences, while a majority had at least one copy of Cebpa or Cebpb (Ramji and Foka, 2002;Pedersen et al, 2007;Dey et al, 2012) binding sites. Binding sites for the cAMP-responsive element binding protein (Creb1) (Kim et al, 2016;Steven et al, 2017) was found in one or two copies in Mfsd6, Mfsd8, Mfsd11, and Unc93b1, three to four copies in Slc22a32, Slc22b5, Slc33a2, Slc59a1, Slc60a1, Slc60a2, Mfsd9, and Mfsd14a, seven to eight copies in Unc93a. The novel regulator of metabolism, E2f1 (Denechaud et al, 2017), had predicted binding sites in 20 out of 29 transporters and 60% of them had more than three copies present, with the highest amount of copies in Mfsd11.…”

“…Three promoter motifs, the TATA box, CCAAT box and the GC box were analyzed. The JASPER CORE 2018 vertebrate library was used to search for transcription factor motifs and several transcriptions factors known to be affected by macronutirent metabolism were analyzed; Atf4 (Averous et al, 2004;Dey et al, 2012), Cebpa (Pedersen et al, 2007), Cebpb (Ramji and Foka, 2002), Creb1 (Kim et al, 2016;Steven et al, 2017), E2f1 (Denechaud et al, 2017), FoxO1 (Kousteni, 2012), Mlx, Mlxip, and Mlxipl (Ma et al, 2006;Havula and Hietakangas, 2012).…”

What turns CREB on? And off? And why does it matter?

“…Surfen is an antagonist for heparan sulfate [110], and its potential CREB-CRE blocking mechanism was described by Rishi and coworkers (2005), who reported that Surfen has a higher specificity for CREB than for C/EBPβ (EC50 0.6 µM vs. 2.5 µM) [112]. Surfen at lower concentrations has been shown to block the binding of CREB to a CRE oligonucleotide, accompanied by reduced proliferation of BC cell lines [111].…”

Gene regulation could be attributed to TCF3 and other key transcription factors in the muscle of pubertal heifers

“…was highly expressed in bovine embryonic cells suggesting its possible role in transcriptional regulation during early genome activation (Vigneault, McGraw, & Sirard, 2009). The gene CREB1 is also metabolically important as it mediates transcriptional responses to different stimuli such as hormones, growth factors and neurotransmitters (Steven et al, 2017). Adipose tissue coordinates the systemic insulin and modulates energy balance through CREB1, implying CREB1 plays an important role in glucose homeostasis and energy metabolism (Qi et al, 2009).…”