epigenetic modification through histone deacetylation. In that spirit, butyrate is a widely known histone deacetylation (HDAC) enzyme inhibitor ( Gao et al. 2009 , Donohoe et al. 2012 ). HDAC inhibition by butyrate regulates cellular proliferation
Mohamed H Noureldein, Sara Bitar, Natalie Youssef, Sami Azar and Assaad A Eid
M Tiedge and S Lenzen
RINm5F insulinoma cells show a defective physiological insulin secretory response to glucose stimulation. The short chain carbonic acid sodium butyrate induced a growth arrest during a 72-h tissue culture period. In contrast to control RINm5F cells, 2 mm glucose increased insulin secretion by more than 70% in these sodium butyrate-treated cells (1 mm) without any further increase of the secretory rate between 2 and 20 mm glucose. This effect of sodium butyrate on insulin secretion was assessed in comparison with its effect on gene expression of the GLUT1 and GLUT2 glucose transporter, hexokinase type I and type II, glucokinase and insulin. Sodium butyrate at a 1 mm concentration decreased GLUT1 gene expression by nearly 50%, but did not induce gene expression of the low-affinity GLUT2 glucose transporter above the detection limit. Furthermore, sodium butyrate increased glucokinase gene expression by more than 50% and hexokinase type II gene expression by more than 100%, while insulin gene expression was increased only by 24%. Hexokinase type II enzyme activity was increased by more than 100% without a concomitant significant change of the glucokinase enzyme activity. Sodium butyrate (2 mm) caused effects comparable with those of 1 mm sodium butyrate. Thus the improved insulin secretory responsiveness of RINm5F insulinoma cells after sodium butyrate treatment at low non-physiological millimolar glucose concentrations can be interpreted as a result of an increased hexokinase-mediated metabolic flux rate through the glycolytic chain.
E Buommino, D Pasquali, AA Sinisi, A Bellastella, F Morelli and S Metafora
Retinoic acid (RA) and sodium butyrate (NaB) are regulators of cell growth and differentiation. We studied their effect on normal (SVC1) or v-Ki-ras-transformed (Ki-SVC1) rat seminal vesicle (SV) epithelial cell lines. The treatment of these cells with 10(-((7( M RA did not produce significant changes in the morphological and biochemical parameters analyzed. When RA was used in combination with 2 mM NaB, the treatment induced substantial morphological changes, apoptosis-independent growth arrest, up-regulation of tissue transglutaminase (tTGase), and down-regulation of beta and gamma RA receptor (RAR) mRNA expression. The same cells did not express RAR alpha either before or after NaB/RA treatment. A similar treatment did not change the amount of mRNA coding for the protein SV-IV (a typical differentiation marker of the SV epithelium) in normal or ras-transformed cells nor the level of v-Ki-ras mRNA in Ki-SVC1 cells. These findings suggest that a defective RA/RARs signaling pathway is probably the biochemical condition that underlies the unresponsiveness to RA of our in vitro culture system, and indirectly points to the possibility that the NaB/RA-induced effects were brought about by a cooperation at the transcription level between the histone deacetylase inhibitory activity of NaB and the ability of RA/RAR to modulate the expression of various genes involved in the control of cell growth and differentiation.
Long The Nguyen, Sonia Saad, Yi Tan, Carol Pollock and Hui Chen
-induced obese mice ( Ozcan et al . 2009 , Çakir et al . 2013 ). Moreover, improving ER function by administration of 4-phenyl butyrate (PBA, a FDA-approved chemical chaperone) in dietary obese mice was able to rescue leptin sensitivity to reduce the level of
D. J. Woods, J. Soden and S. P. Bidey
Using the fluorescent indicators 2′,7′-bis(2-carboxyethyl)-5′-(6′)-carboxyfluorescein and Oxonol V to monitor intracellular pH (pHi) and cell membrane potential respectively, we have investigated the involvement of H+-dependent ATPase and H+-dependent K+ channels in the recovery of the rat thyroid cell strain FRTL-5 from experimentally induced cytosolic acidification and membrane hyperpolarization events. Following exposure of cells to the weak acid sodium butyrate (24mmol/l) under bicarbonate-free incubation conditions, cytoplasmic acidification was maximal after 3 min, attaining a pHi of 6.42. The subsequent recovery of pHi was unimpaired by the absence of extracellular K+, but was reduced in the presence of the Na+ antagonist amiloride (1 mmol/l), recovering by 0.11±0.003 units, compared with 0.27±0.02 units under amiloride-free conditions. In the presence of the H+-dependent ATPase antagonist N,N′-dicyclohexylcarbodiimide (DCC), the pHi recovery observed in amiloride-containing, K+-free buffer was abolished.
The recovery of pHi in Na+- and K+-containing buffer was accompanied by hyperpolarization of the cell membrane, the later stage of which was reduced after blockade of K+ channels with BaCl2, implying a major contribution of transmembrane K+ movement to such events. In contrast to its attenuating effect on pHi recovery, DCC was ineffective in reducing butyrate-dependent membrane hyperpolarization, suggesting that H+-dependent ATPase may not be a major contributory factor to this event. However, when K+ channels were blocked by addition of BaCl2, addition of DCC abolished the butyrate-induced membrane depolarization. These findings are consistent with the presence of two independent hyperpolarizing transport processes in the FRTL-5 cell membrane which appear to involve (i) a H+-dependent ATPase, activated in response to cytosolic acidification, and allowing partial recovery of pHi in the absence of extracellular Na+ and HCO3 −, and (ii) H+-dependent K+ channels which, while contributing to membrane hyperpolarization, may not play a major role in the normal maintenance of pHi.
A Evdokiou, LJ Raggatt, T Sakai and DM Findlay
The cyclin-dependent kinase inhibitor p21/WAF1/CIP1 is induced in many cell types in response to a variety of extracellular signals and causes cell cycle arrest in both the G1 and G2/M phases of the cell cycle. We reported previously that calcitonin (CT) receptor (CTR)-mediated growth inhibition of HEK-293 cells stably transfected with the human CTR is accompanied by a rapid and sustained induction of p21 and cell cycle arrest in G2. In the present study we have shown that CT stimulates transcription from a p21 promoter-luciferase construct. Using deletion and mutation analysis of the p21 promoter we have demonstrated that transcriptional activation of p21 by CT is p53-independent and is mediated through specific activation of Sp1-binding sites in a region of the promoter between -82 and -69, relative to the transcription start site. CTR-mediated transcriptional activation of p21 was specific for the insert-negative isoform of the human CTR. Butyrate, which was shown previously to activate the same Sp1 site, synergised with CT to increase further p21 promoter activity. These results provide the first demonstration that CTR can induce gene transcription through the constitutively expressed transcription factor Sp1, and define a mechanism of cell growth suppression that may have implications for other members of the seven-transmembrane domain G protein-coupled receptor superfamily.
MJ Haas, K Pun, D Reinacher, NC Wong and AD Mooradian
To determine if ketoacidosis contributes to reduced apolipoprotein A1 (apoA1) expression in insulin-deficient diabetic rats, we examined the regulation of apoA1 gene expression in response to changes in ambient pH or ketone body concentrations. Hepatic apoAI mRNA levels were reduced 42% in diabetic rats relative to nondiabetic controls (means+/-s.d.; 321.8+/-43.7 vs 438.7+/-58.8 arbitrary units; P<0.03). Neither endogenous apoA1 mRNA nor transcriptional activity of the rat apoA1 gene promoter (from -474 to -7) were altered by sodium butyrate or isobutyramide (0.3 mM to 10 mM) in Hep G2 or Caco-2 cells. Rat hepatic and intestinal apoA1 mRNA levels, and plasma apoA1 concentration, were not altered 24 h after isobutyramide administration (500 mg/kg by gavage). When the effect of altering ambient pH within a wide range commonly encountered in vivo was studied, acidosis (pH 6.7), relative to alkalosis (pH 7.9), decreased apoAI mRNA levels relative to glyceraldehyde-3-phosphate dehydrogenase mRNA by 47% in Hep G2 cells (P<0.025) and by 24% in Caco-2 cells (P<0.017). Acidosis did not alter cytomegalo virus (CMV)-beta-galactosidase activity, or the activity of the simian virus (SV40) early-region promoter, in either cell line transfected with the respective constructs. The lowering of ambient pH was associated with a graded reduction in apoAI promoter activity. At pH 6.7, apoAI promoter activity was reduced by 75% compared with promoter activity at pH 7.9. These observations indicate that acidosis, but not ketosis, contributes to the reduction in apoA1 expression during diabetic ketoacidosis by down-regulating apoAI promoter activity.
Hayden Weng Siong Tan, Arthur Yi Loong Sim, Su Ling Huang, Ying Leng and Yun Chau Long
repression of gene expression ( De Ruijter et al . 2003 ). Recent studies suggest that HDACs play a role in the regulation of skeletal muscle metabolism. Dietary supplementation of butyrate prevented diet-induced insulin resistance in mice, and this effect
Masaki Shiota, Akira Yokomizo and Seiji Naito
) Depsipeptide HDAC inhibitor LNCaP − Transcription? NA Rokhlin et al . (2006) Sodium butyrate HDAC inhibitor LNCaP − Transcription? NA Rokhlin et al . (2006) Sodium butyrate HDAC inhibitor LNCaP + NA NA Kim et al . (2007) Suberoylanilide hydroxamic acid
Benjamin Kalbe, Marian Schlimm, Julia Mohrhardt, Paul Scholz, Fabian Jansen, Hanns Hatt and Sabrina Osterloh
( Schmiedeberg et al. 2007 ) and OR2J3 ( Adipietro et al. 2012 )); odorant mixture 2 (OM2): amyl butyrate (OR2AG1 ( Neuhaus et al. 2006 )), methyl octonoate (OR52D1 ( Sanz et al. 2005 )) and PI-23472 (OR4D1 ( Veitinger et al. 2011 )); odorant mixture 3