• Animal cells and systems
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• v.13 no.3
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• pp.283-288
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• 2009

The ubiquitous plasma membrane $Na^+/H^+$ exchanger 1 (NHE1) is rapidly activated in response to various extracellular stimuli and maintains normal cytoplasmic pH. Yeast two-hybrid screening was used in order to identify proteins interacting with NHE1 using its cytoplasmic domain as a bait from HeLa cDNA library. One of the interacting cDNA clones was human Lactate dehydrogenase B (LDHB). In vitro translated LDHB was pulled down together with GST-NHE1.cd protein in the GST pull down assay, confirming the interaction in vitro. LDHB antibody immunoprecipitated endogenous LDHB together with NHE1 from H9c2 cells, validating cellular interaction between NHE1 and LDHB. Subsequent analysis revealed that the overexpression of LDHB increased intracellular PH, implying opening of the NHE1 transporter. Moreover, overexpression of LDHB activated caspase 3 and induced cell death, consistent with the expected phenotype of hyper-activation of NHE1. Collectively, our data indicate that LDHB modulates NHE1 activity via physical interaction.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.8
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• pp.1060-1068
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• 2011

The LDH isozymes are key catalysts in the glycolytic pathway of energy metabolism. It is well known that the distribution of the LDH isozymes vary in accordance with the metabolic requirements of different tissues. The substrates required for energy production change noticeably at successive stages of testes development suggesting a significant flexibility in the expression of glycolytic enzymes. Therefore, expression of LHDA and LDHB mRNAs was examined in adult and prepubertal quail testis. The mRNA of both LDHA and LDHB were expressed and no significant difference was observed in prepubertal testes. The mRNA levels of LDHB significantly increased during testicular development. In the adult testis, LDHA mRNA was not expressed. Expression studies revealed the presence of different LDH isozymes during testicular development. In contrast, electrophoresis of both testicular samples revealed only single band at a position indicative of an extreme type of LDH isozyme in quail testes. Furthermore, nucleotide and amino acid sequence analysis revealed significant similarity to chicken, duck and rock pigeon. These sequence results confirmed the similarity of LDHA and LDHB subunit protein in different avian species.

• The Korean Journal of Zoology
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• v.36 no.2
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• pp.193-199
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• 1993

The protein po;vmorphisms and allele frequencies of wild house rat (Rattus norvegicus) population in Korea were studied. The studied proteins and enzymes were transferrin (Tf), albumin (Alb), fumarate hvdratase (FH), phospho!loucomutase (PGM), lactate dehvdrogenase A (LDHA) and lactate dehvdrogenase B (LDHB). There were two transferrin alleles, TP and Tf in Korean wild house rat popu1ation. The Tf2 allele was found for the first time by a starch gel, and confirmed by a polvacrvlamide gel isoelectric focusing and immunoblotting. The allele frequencies of TP and TF were 0.985 and 0.015, respectively. Two common alleles fumarate hydratase, FHa and FHb were found, and frequencies of FHa and FPP were calculated to be 0.714 and 0.286, respectively. The kequenw of FH in Korean wild house rat was higher than that of Finnish and Czechoslovakian population. Alb, PGM, LDHA and LDHB are only one phenotype each and all. Therefore, these proteins seem to be monomorphic in Korean wild house rat population.

• Development and Reproduction
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• v.16 no.3
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• pp.219-226
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• 2012

It is suggested that carbohydrate metabolites may involve in the development of morula to blastocyst but many of the mechanisms are not unmasked. Two-cell stage embryos were collected and examined the effects of lactate on the development of blastocyst in vitro. The expression profiles of lactate dehydrognase (Ldh) genes and aquaporin (Aqp) genes were analyzed with RT-PCR. The successful development from morula to blastocyst was dependent on lactate concentrations. The expression profiles of Ldh genes were changed by the lactate concentration. Ldha was expressed in morula stage at 10 mM lactate, and in blastocyst stage at lactate free condition. Ldhb was expressed in morula stage at 10 mM and 20 mM lactate, and in blastocyst stage at 10 mM lactate. Aqp genes were also showed different expression patterns by the lactate concentrations. Aqp3 was expressed in hatching embryo at 120 hr post hCG administration (hph) which was cultured in BWW medium and lactate free condition. Aqp7 was expressed in hatching embryos at 120 hph which was cultured at 10 mM lactate condition. Also Aqp8 was expressed in hatching embryo at BWW and 20 mM lactate condition. Aqp9 was expressed in morula at BWW and 10 mM lactate condition, and in blastocyst at BWW. Based on these results, it is suggested that concentration of lactate in the medium and the level of lactate synthesis in embryo is critical factor for blastocoels formation. In addition it is suggested that LDH may involve the AQPs expression in embryos.

• Journal of Life Science
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• v.29 no.11
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• pp.1179-1191
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• 2019

Cancer cells undergo the epithelial-mesenchymal transition (EMT) and show unique oncogenic metabolic phenotypes such as the glycolytic switch (Warburg effect) which are important for tumor development and progression. The EMT is a critical process for tumor invasion and metastasis. High-mobility group box 1 (HMGB1) is a chromatin-associated nuclear protein, but it acts as a damage-associated molecular pattern molecule when released from dying cells and immune cells. HMGB1 induces the EMT, as well as invasion and metastasis, thereby contributing to tumor progression. Here, we show that HMGB1 induced the EMT by activating Snail. In addition, the HMGB1/Snail cascade was found induce a glycolytic switch. HMGB1 also suppressed mitochondrial respiration and cytochrome c oxidase (COX) activity by a Snail-dependent reduction in the expression of the COX subunits COXVIIa and COXVIIc. HMGB1 also upregulated the expression of several key glycolytic enzymes, including hexokinase 2 (HK2), phosphofructokinase-2/fructose-2,6-bisphosphatase 2 (PFKFB2), and phosphoglycerate mutase 1 (PGAM1), in a Snail-dependent manner. However, HMGB1 was found to regulate some other glycolytic enzymes including lactate dehydrogenases A and B (LDHA and LDHB), glucose transporter 1 (GLUT1), and monocarboxylate transporters 1 and 4 (MCT1 and 4) in a Snail-independent manner. Transfection with short hairpin RNAs against HK2, PFKFB2, and PGAM1 prevented the HMGB1-induced EMT, indicating that glycolysis is associated with HMGB1-induced EMT. These findings demonstrate that HMGB1 signaling induces the EMT, glycolytic switch, and mitochondrial repression via Snail activation.