Abstract. The nuclear import of transcription regulatory proteins appears to be used by the cell to trigger transitions in cell cycle, morphogenesis, and transformation . We have previously observed that the rate at which SV-40 T antigen fusion proteins containing a functional nuclear localization sequence (NLS; residues 126-132) are imported into the nucleus is enhanced in the presence of the casein kinase R (CK-II) site Si"ai2 . In this study purified p34cdc2 kinase was used to phosphorylate T antigen proteins specifically at T'24 and kinetic measurements at the single-cell level performed to assess its effect on nuclear protein import . Tí24 phosphorylation, which could be functionally simulated by a T-to-13 124 substitution, was found to reduce the maximal extent of nuclear accumulation whilst negligibly affecting the import C LOSE correlations between the nuclear cytoplasmic distribution ofcertain transcription factors (Lenardo and

The aim of our studies was to determine the amount of polyphenols reaching the colon after oral intake of apple juice and blueberries. After a polyphenol-free diet healthy ileostomy volunteers consumed a polyphenol-rich cloudy apple juice while others consumed anthocyanin-rich blueberries. Ileostomy effluent was collected and polyphenols were identified using HPLC-DAD as well as HPLC-ESI-MS/MS; quantification was performed with HPLC-DAD. Most of the orally administered apple polyphenols were absorbed from or metabolized in the small intestine. Between 0 and 33% of the oral dose was recovered in the ileostomy bags with a maximum of excretion after 2 h. A higher amount of the blueberry anthocyanins under study (up to 85%, depending on the sugar moiety) were determined in the ileostomy bags and therefore would reach the colon under physiological circumstances. Such structure-related availability has to be considered when polyphenols are used in model systems to study potential preventive effects in colorectal diseases.

The findings relating to the absorption, metabolism, and systemic availability of polyphenols in vivo should contribute to our understanding of their biological effects, and the characterization of newly formed metabolites should facilitate further studies.

No abstract

Hydrogen sulfide (H2S) is the first inorganic compound identified as both a substrate for mitochondrial oxidative phosphorylation and a transmitter in mammalian cells. H2S seems to mediate effects that are correlated with those of nitric oxide (NO) by a reciprocal regulation. Moreover, H2S is consumed by mitochondrial oxidation mediated by sulfide-quinone reductase-like protein (SQRDL)-the vertebrate homolog of sulfide-quinone oxidoreductase (SQR). There is evidence that SQR plays an essential role in regulating H2S levels in fission yeast. To start understanding the role of SQRDL in the mammalian metabolism of H2S, we examine rat tissues. Our results show that SQRDL protein is present in all tissues tested, albeit restricted to specific mitochondrial populations at the cellular level. We demonstrate a developmental regulation of Sqrdl transcription in the kidney, where SQRDL protein is detectable in glomerular podocytes and in tubular cells of the renal medulla. We also show that Sqrdl transcription in T cells is responsive to external H2S. Taken together, our results suggest that Sqrdl transcription is adaptively regulated, probably to meet the need of H2S oxidation. Thus far, SQRDL has only been studied in a limited set of tissues. The present report demonstrates the presence and specific localization of SQRDL in various mammalian tissues.