Project description:Hexokinase catalyzes the first committed step in glucose metabolism by phosphorylating glucose to produce glucose-6-phosphate. Highly glycolytic proliferating cells such as cancer cells take advantage of HK2 expression to accelerate glucose metabolism even in the presence of oxygen. This acceleration not only provides sufficient glycolytic intermediates to support the anabolic demands of the cells but also inevitably accompanies increased formation of metabolic end products such as lactate. Currently, the effect of lactate caused by HK2-mediated metabolic alteration is largely unknown. A recent study found that lactate plays a role in an epigenetic alteration known as histone lactylation. Here, using RNA-seq and CUT&Tag chromatin profiling, we study the effect of HK2 and lactate on gene expression via histone lactylation (H3K18la).
Project description:Hexokinase catalyzes the first committed step in glucose metabolism by phosphorylating glucose to produce glucose-6-phosphate. Highly glycolytic proliferating cells such as cancer cells take advantage of HK2 expression to accelerate glucose metabolism even in the presence of oxygen. This acceleration not only provides sufficient glycolytic intermediates to support the anabolic demands of the cells but also inevitably accompanies increased formation of metabolic end products such as lactate. Currently, the effect of lactate caused by HK2-mediated metabolic alteration is largely unknown. A recent study found that lactate plays a role in an epigenetic alteration known as histone lactylation. Here, using RNA-seq and CUT&Tag chromatin profiling, we study the effect of HK2 and lactate on gene expression via histone lactylation (H3K18la).
Project description:Lactate was implicated in activation of hepatic stellate cells (HSCs). However, the mechanism by which lactate exerts its effect remains elusive. We show that hexokinase 2 (HK2) is sufficient to change gene expression by histone lactylation but not histone acetylation. Using RNA-seq and CUT&Tag chromatin profiling, we found that induction of HK2 expression in activated HSCs is required for the induced gene expression by elevating histone lactylation. Inhibiting histone lactylation by Hk2 deletion or pharmacological inhibition of lactate production diminishes HSC activation, whereas exogenous lactate but not acetate supplementation rescues the activation phenotype. Thus, lactate produced by activated HSCs determines the HSC fate via histone lactylation. We found that histone acetylation competes with histone lactylation, which could explain why class I HDAC inhibitors impede HSC activation. Finally, HSC-specific or systemic deletion of HK2 inhibits HSC activation and liver fibrosis in vivo. Therefore, we provide evidence that HK2 may be an effective therapeutic target for liver fibrosis.
Project description:MicroRNAs (miRNAs) have emerged as important gene regulators and are recognized as key players in tumorigenesis. miR-143 is reported to be down-regulated in several cancers, but knowledge of its targets in colon cancer remains limited. To investigate the role of miR-143 in colon cancer, we have employed a microarray based approach to identify miR-143 targets. Based on seed site enrichment analyses and unbiased word analyses, we found a significant enrichment of miRNA binding sites in the 3M-bM-^@M-^Y-untranslated regions (UTRs) of transcripts down-regulated upon miRNA overexpression. Here we identify Hexokinase 2 (HK2) as a direct target of miR-143 and show that re-introduction of miR-143 in the colon cancer cell line DLD-1 results in a decreased lactate secretion, indicating that miR-143 down-regulation of HK2 affects glucose metabolism in colon cancer cells. DLD-1 cells were transfected with 50 nM miR-143 duplex or mock transfected. Total RNA was harvested 24 hours post-transfection and analyzed on Affymetrix HG-U133 Plus 2.0 human arrays.
Project description:Lactate was implicated in activation of hepatic stellate cells (HSCs). However, the mechanism by which lactate exerts its effect remains elusive. We show that hexokinase 2 (HK2) is sufficient to change gene expression by histone lactylation but not histone acetylation. Using RNA-seq and CUT&Tag chromatin profiling, we found that induction of HK2 expression in activated HSCs is required for the induced gene expression by elevating histone lactylation. Inhibiting histone lactylation by Hk2 deletion or pharmacological inhibition of lactate production diminishes HSC activation, whereas exogenous lactate but not acetate supplementation rescues the activation phenotype. Thus, lactate produced by activated HSCs determines the HSC fate via histone lactylation. We found that histone acetylation competes with histone lactylation, which could explain why class I HDAC inhibitors impede HSC activation. Finally, HSC-specific or systemic deletion of HK2 inhibits HSC activation and liver fibrosis in vivo. Therefore, we provide evidence that HK2 may be an effective therapeutic target for liver fibrosis.
Project description:MicroRNAs (miRNAs) have emerged as important gene regulators and are recognized as key players in tumorigenesis. miR-143 is reported to be down-regulated in several cancers, but knowledge of its targets in colon cancer remains limited. To investigate the role of miR-143 in colon cancer, we have employed a microarray based approach to identify miR-143 targets. Based on seed site enrichment analyses and unbiased word analyses, we found a significant enrichment of miRNA binding sites in the 3’-untranslated regions (UTRs) of transcripts down-regulated upon miRNA overexpression. Here we identify Hexokinase 2 (HK2) as a direct target of miR-143 and show that re-introduction of miR-143 in the colon cancer cell line DLD-1 results in a decreased lactate secretion, indicating that miR-143 down-regulation of HK2 affects glucose metabolism in colon cancer cells.
Project description:L. plantarum is known to possess an L-lactate inducible lactate racemase activity (Goffin et al. 2005. J. Bacteriol. 187:6750). In the present study, microarrays were used in order to identify all genes that are up-regulated by L-lactate, but not by a racemic mixture of D- and L-lactate. A mutant of L. plantarum NCIMB8826 deficient for NAD-dependent L-lactate activity (TF101; Ferain et al. 1994. 176:596), and thus producing no L-lactate, was grown in MRS medium at 28°C until mid-exponential phase (OD600nm 0.75). The culture was then divided into 3 sub-cultures. Optically pure sodium L-lactate (200 mM) was added to the first sub-culture (TF101 + L-lac 200 mM). An equimolar mixture of sodium D- and L-lactate (100 mM each) was added to the second sub-culture (TF101 + L/D-lac 200 mM). The third sub-culture was not treated (TF101; reference sample). The three sub-cultures were further incubated at 28°C for 1h30 (a time known to be sufficient for induction of lactate racemase activity by L-lactate). Cells were harvested by centrifugation. Microarray data were used ot identify genes that are specifically induced by L-lactate (comparison of TF101 with TF101 + L-lac 200 mM), but not by DL-lactate (comparison of TF101 with T101 + L/D-lac 200 mM). There are no biological replicates.