Genome-wide gene expression responses to experimental manipulation of Saccharomyces cerevisiae repressor activator protein 1 (Rap1) expression level.

Precise regulation of transcription in gene expression is critical for all aspects of normal organism form, fitness, and function and even minor alterations in the level, location, and timing of gene expression can result in phenotypic variation within and between species including evolutionary innovations and human disease states. Eukaryotic transcription is regulated by a complex interplay of multiple factors working both at a physical and molecular levels influencing this process. In Saccharomyces cerevisiae, the TF with the greatest number of putative regulatory targets is the essential gene Repressor Activator Protein 1 (RAP1). While much is known about the roles of Rap1 in gene regulation and numerous cellular processes, the response of Rap1 target genes to systematic titration of RAP1 expression level remains unknown. To fill this knowledge gap, we used a strain with a tetracycline-titratable promoter replacing wild-type regulatory sequences of RAP1 to systematically reduce the expression level of RAP1 and followed this with RNA sequencing (RNA-seq) to measure genome-wide gene expression responses. Previous research indicated that Rap1 plays a significant regulatory role in particular groups of genes including telomere-proximal genes, homothallic mating (HM) loci, glycolytic genes, DNA repair genes, and ribosomal protein genes; therefore, we focused our analyses on these groups and downstream targets to determine how they respond to reductions in RAP1 expression level. Overall, despite being known as both an activator and as a repressor of its target genes, we found that Rap1 acts as an activator for more target genes than as a repressor. Additionally, we found that Rap1 functions as an activator of ribosomal protein genes and a repressor for HM loci genes consistent with predictions from the literature. Unexpectedly, we found that Rap1 functions as a repressor of glycolytic enzyme genes contrary to prior reports of it having the opposite effect. We also compared the expression of RAP1 to five different genes related to DNA repair pathway and found that decreasing RAP1 downregulated four of those five genes. Finally, we found no effect of RAP1 depletion on telomere-proximal genes despite its functioning to silence telomeric repeat-containing RNAs. Together our results enrich our understanding of this important transcriptional regulator.

Effects of carnosine and related compounds on the stability and morphology of erythrocytes from alcoholics.

The effects of carnosine and related compounds on erythrocytes from alcoholics were studied. In their presence, erythrocytes showed an increased ability to resist haemolysis and showed a more normal morphology, with carnosine and N-acetyl-carnosine being the most effective compounds. These beneficial properties of the dipeptides do not appear to be directly related to their antioxidant or buffering properties.

[Effect of carnosine and its N-acetyl derivative on the stability of erythrocytes in patients with alcoholism during abstinence]. / Vliianie karnozina i ego N-atsetil'nogo proizvodnogo na stabil'nost' éritrotsitov bol'nykh alkogolizmom v sostoianii abstinentsii.

The effects of carnosine, a natural dipeptide, and its derivative, N- acetyl-carnosine (Ac-carnosine), on the stability and shape of red blood cells obtained from abstinent alcoholics was studied. In the presence of both carnosine and Ac-carnosine, the erythrocytes of abstinent alcoholics show a statistically significant increase in their ability to resist acidic hemolysis. Investigations of microscope pictures also show that carnosine and Ac-carnosine have beneficial effects on the pathological state of abstinent alcoholic erythrocytes. The addition of carnosine and Ac-carnosine resulted in the normalization of cell morphology (in 12 and 17 out of 30 cases, respectively). These results may be due to the stabilizing and regenerating ability of these compounds on alcoholic erythrocytes.