Background:The function of KLF11/TIEG2 under stressful conditions is undefined. Results: KLF11 increases brain MAO expression through its promoter and a chromatin partner, which can be enhanced by stress. Conclusion: This is the first elucidation of mechanisms underlying stress-induced KLF11-MAO up-regulation. Significance: This novel KLF11-MAO pathway may play an important role in stress-related brain disorders.

Background Alcoholism is a major psychiatric condition at least partly associated with ethanol-induced cell damage. Although brain cell loss has been reported in subjects with alcoholism, the molecular mechanism is unclear. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and monoamine oxidase B (MAO B) reportedly play a role in cellular dysfunction under stressful conditions and may contribute to ethanol-induced cell damage. Methods Expression of GAPDH and MAO B protein was studied in human glioblastoma and neuroblastoma cell lines exposed to physiological concentrations of ethanol. Expression of these proteins was also examined in the prefrontal cortex from human subjects with alcohol dependence and in rats fed with an ethanol diet. Co-immunoprecipitation, subcellular fractionation, and luciferase assay were used to address nuclear GAPDH-mediated MAO B activation. To test the effects of inactivation, RNAi and pharmacological intervention were used, and cell damage was assessed by TUNEL and H2O2 measurements. Results Ethanol significantly increases levels of GAPDH, especially nuclear GAPDH, and MAO B in neuronal cells as well as in human and rat brains. Nuclear GAPDH interacts with the transcriptional activator, transforming growth factor-beta-inducible early gene 2 (TIEG2), and augments TIEG2-mediated MAO B transactivation, which results in cell damage in neuronal cells exposed to ethanol. Knockdown expression of GAPDH or treatment with MAO B inhibitors selegiline (Deprenyl) and rasagiline (Azilect) can block this cascade. Conclusions Ethanol-elicited nuclear GAPDH augments TIEG2-mediated MAO B, which may play a role in brain damage in subjects with alcoholism. Compounds that block this cascade are potential candidates for therapeutic strategies.

R. Salt-sensitive splice variant of nNOS expressed in the macula densa cells. Am J Physiol Renal Physiol 298: F1465-F1471, 2010. First published March 24, 2010 doi:10.1152/ajprenal.00650.2009.-Neuronal nitric oxide synthase (nNOS), which is abundantly expressed in the macula densa cells, attenuates tubuloglomerular feedback (TGF). We hypothesize that splice variants of nNOS are expressed in the macula densa, and nNOS-␤ is a salt-sensitive isoform that modulates TGF. SpragueDawley rats received a low-, normal-, or high-salt diet for 10 days and levels of the nNOS-␣, nNOS-␤, and nNOS-␥ were measured in the macula densa cells isolated with laser capture microdissection. Three splice variants of nNOS, ␣-, ␤-, and ␥-mRNAs, were detected in the macula densa cells. After 10 days of high-salt intake, nNOS-␣ decreased markedly, whereas nNOS-␤ increased two-to threefold in the macula densa measured with real-time PCR and in the renal cortex measured with Western blot. NO production in the macula densa was measured in the perfused thick ascending limb with an intact macula densa plaque with a fluorescent dye DAF-FM. When the tubular perfusate was switched from 10 to 80 mM NaCl, a maneuver to induce TGF, NO production by the macula densa was increased by 38 Ϯ 3% in normal-salt rats and 52 Ϯ 6% (P Ͻ 0.05) in the high-salt group. We found 1) macula densa cells express nNOS-␣, nNOS-␤, and nNOS-␥, 2) a high-salt diet enhances nNOS-␤, and 3) TGF-induced NO generation from macula densa is enhanced in high-salt diet possibly from nNOS-␤. In conclusion, we found that the splice variants of nNOS expressed in macula densa cells were ␣-, ␤-, and ␥-isoforms and propose that enhanced level of nNOS-␤ during high-salt intake may contribute to macula densa NO production and help attenuate TGF. nitric oxide; tubuloglomerular feedback; high-salt diet MACULA DENSA CELLS serve as a distal nephron sensor that detects changes in tubular fluid composition and transmits information to afferent arteriolar smooth muscle cells [tubuloglomerular feedback (TGF)] and renin-containing granular cells (21). Nitric oxide (NO) is one of the most important factors that regulate TGF. This NO, which sets the sensitivity of the TGF system, is mainly generated by neuronal NO synthase (nNOS) that is abundantly expressed in the macula densa cells (20,41). Expression of nNOS in the macula densa is modulated by salt intake; a high-salt diet decreases nNOS expression, whereas a low-salt diet increases it (3,29,33). However, this pattern of expression of nNOS is contrary to what one would expect, because NO activity is increased, rather than decreased, during a high-salt diet (8,26,28,35). Indeed, increasing either salt intake or delivery to the macula densa elevates macula densa NO levels and attenuates TGF in vivo and in vitro (16,18,38). Although the reasons for this discrepancy between NO activity and expression of nNOS are not known, several possibilities exist including 1) increased activity of the nNOS enzyme, 2) an alternative source of NO, and 3) the presenc...

Brain cell loss has been reported in subjects with alcoholism. However, the molecular mechanisms are unclear. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and monoamine oxidase B (MAO B) reportedly play a role in cellular dysfunction with regards to ethanol exposure. We have recently reported that GAPDH protein expression was increased in the brains of rats fed with ethanol. Furthermore, GAPDH interacts with the transcriptional activator, transforming growth factor-beta-inducible early gene 2 (TIEG2), to augment TIEG2-mediated MAO B activation, resulting in neuronal cell damage due to ethanol exposure. The current study investigates whether the TIEG2-MAO B cascade is also active in the brains of rats fed with ethanol. Ten ethanolpreferring rats were fed with a liquid diet containing ethanol, with increasing amounts of ethanol up to a final concentration of 6.4% representing a final diet containing 36% of calories for 28 days. Ten control rats were fed the liquid diet without ethanol. The expression of TIEG2 protein, MAO B mRNA levels, MAO B catalytic activity, and the levels of anti-apoptotic protein Bcl 2 and apoptotic protein caspase 3 were determined in the prefrontal cortex of the rats. Ethanol significantly increased protein levels of TIEG2, active caspase 3, MAO B mRNA and enzyme activity, but significantly decreased Bcl 2 protein expression compared to control rats. In summary, ethanol increases the TIEG2-MAO B brain cell death cascade in rat brains, suggesting that the TIEG2-MAO B pathway is a novel pathway for brain cell damage resulting from ethanol exposure, and may contribute to chronic alcohol-induced brain damage.