Altered modulation of lamin A/C‐HDAC2 interaction and p21 expression during oxidative stress response in HGPS

Defects in stress response are main determinants of cellular senescence and organism aging. In fibroblasts from patients affected by Hutchinson–Gilford progeria, a severe LMNA‐linked syndrome associated with bone resorption, cardiovascular disorders, and premature aging, we found altered modulation of CDKN1A, encoding p21, upon oxidative stress induction, and accumulation of senescence markers during stress recovery. In this context, we unraveled a dynamic interaction of lamin A/C with HDAC2, an histone deacetylase that regulates CDKN1A expression. In control skin fibroblasts, lamin A/C is part of a protein complex including HDAC2 and its histone substrates; protein interaction is reduced at the onset of DNA damage response and recovered after completion of DNA repair. This interplay parallels modulation of p21 expression and global histone acetylation, and it is disrupted by LMNAmutations leading to progeroid phenotypes. In fact, HGPS cells show impaired lamin A/C‐HDAC2 interplay and accumulation of p21 upon stress recovery. Collectively, these results link altered physical interaction between lamin A/C and HDAC2 to cellular and organism aging. The lamin A/C‐HDAC2 complex may be a novel therapeutic target to slow down progression of progeria symptoms.     

XX/XY sex chromosome system and chromosome markers in the snake eel Ophisurus serpens (Anguilliformes: Ophichtidae)

We report evidence of an XX/XY sex chromosome system in the snake eel Ophisurus serpens (Anguilliformes: Ophichthidae). We characterized the male and female karyotypes by C-, replication- and HaeIII-bandings. The 45S and 5S ribosomal gene families were located using dual fluorescence in situ hybridization, which showed that the 5S rDNA sites were present on the X chromosome, beside an autosome pair. FISH with a telomeric peptide nucleic acid probe enabled recognition of Interstitial Telomeric Sequences (ITSs), likely remnants of chromosomal rearrangements, in five chromosome pairs, including the rDNA-bearing ones. Possible mechanisms of the origin of sex chromosomes in this species are discussed, considering the presence of a sex-linked marker and ITSs.     

Combination of Multiplex PCR and PCR-Denaturing Gradient Gel Electrophoresis for Monitoring Common Sourdough-Associated Lactobacillus Species

A combination of denaturing gradient gel electrophoresis (DGGE) and a previously described multiplex PCR approach was employed to detect sourdough lactobacilli. Primers specific for certain groups of Lactobacillus spp. were used to amplify fragments, which were analyzed by DGGE. DGGE profiles obtained from Lactobacillus type strains acted as standards to analyze lactobacilli from four regional Abruzzo (central Italy) sourdoughs.     

The l-isoform but not d-isoforms of a JNK inhibitory peptide protects pancreatic beta-cells

The activation of c-jun N-terminal kinase (JNK) in pancreatic islets is associated with impaired function and viability, and JNK inhibitory peptides (JNKIs) are cytoprotective. In particular, l-isoforms of JNKIs were shown to improve islets viability, while the d-retroinverso isoform of JNKI (RI-JNKI), with a higher therapeutic potential due to longer half-life, has not been studied. We compared the cytoprotective properties of L-JNKI and RI-JNKI. Treatment of murine islets with L-JNKI resulted in preservation of islet equivalents and greater percentage of viable beta-cells in culture. In contrast, RI-JNKI was not protective. We found that L-JNKI but not RI-JNKI prevents endogenous c-jun phosphorylation in insulinoma cells. Moreover, RI-JNKI induced islet cells necrosis and activates the p-38 kinase. In conclusion, L-JNKI directly affects beta-cells and ameliorates islet viability and function, while RI-JNKI has toxic effects, limiting its biological application to islet cell biology.     

X-ray structures of new dipeptide taste ligands

The molecular basis of sweet taste was investigated by carrying out the crystal state conformational analysis by X-ray diffraction of the following dipeptide taste igands:N-3,3-dimethylbutyl-aspartyl-phenylalanine methyl ester, I (N-DMB-Asp-Phe-OMe), its sodium salt (N-DMB-Asp-Phe-ONa), II , aspartyl-D -2-aminobutyric acid-(S)-α-ethylbenzylamide, III (Asp-D -Abu-(S)-α-ethylbenzylamide), aspartyl-N′-((2,2,5,5-tetramethylcyclopentanyl)-carbonyl)-(R)-1,1-diamino-ethane, IV (Asp-(R)-gAla-TMCP), and aspartyl-D -valine-(R)-α-methoxymethylbenzyl amide, V (Asp-D -Val-(R)-α-methoxymethylbenzylamide). With the exception of the sodium salt II , all compounds are sweet-tasting, showing in some cases considerable potency enhancement with respect to sucrose. The results of this study confirm the earlier model that an ‘L-shape’ molecular array is essential for eliciting sweet taste for dipeptide-like ligands. In addition, it was established that (i) substitution of the N-terminal group does not inhibit sweet taste, if its zwitterionic character is maintained; (ii) a hydrophobic group located between the stem and the base of the L-shape could be responsible for sweetness potency enhancement, as found in I, III and IV ; in fact, the extraordinary potency of the N-alkylated analogue I would support a model with an additional hydrophobic binding domain above the base of the ‘L’; (iii) removal of the methyl ester at the C-terminus of compound I with the salt formation gives rise to the tasteless compound II ; (iv) for the first time all possible side-chain conformers (g⁻,g⁺andt) for the N-substituted aspartyl residue were observed; and (v) a retro-inverso modification, incorporated at position 2 of the dipeptide chain, confers greater flexibility to the molecule, as demonstrated by the contemporary presence of six conformationally distinct independent molecules in the unit cell and yet sweet taste properties are maintained, as found in IV . © 1998 European Peptide Society and John Wiley & Sons, Ltd.     

Helical screw sense of peptide molecules: The pentapeptide system (Aib)4/L-Val[L-(αMe)Val] in the crystal state

The crystal-state preferred conformations of six N^α-blocked pentapeptide esters, each containing four helicogenic, achiral α-aminoisobutyric acid (Aib) residues followed by one chiral L -valine (L -Val) or C^α-methyl-L -valine [(αMe)Val] residue at the C-terminus, have been assessed by x-ray diffraction analysis. In all of the compounds the  (Aib)₄ sequence is folded in a regular 3₁₀-helical conformation. In the four pentapeptides characterized by the L -(αMe)Val residue two conformationally distinct molecules occur in the asymmetric unit. Conversely, only one molecule is observed in the asymmetric unit of two pentapeptides with the C-terminal L -Val residue. In the L -Val based peptides the helical screw sense of the  (Aib)₄ sequence is right-handed, whereas in the L  (αMe)Val analogues both right- and left-handed helical screw senses concomitantly occur in the two crystallographically independent molecules. © 1998 John Wiley & Sons, Inc. Biopoly 46: 433–443, 1998     

Histone deacetylase inhibitors and hemoglobin F induction in beta-thalassemia

Epigenomic modifiers, such as histone deacetylase inhibitors, are compounds that regulate gene expression by interfering with the enzymatic machinery that maintains the proper chromatin structure of the nucleus. These compounds are at the forefront of novel therapeutic agents for the treatment of several diseases including cancer and genetic disorders such as beta-thalassemia and sickle cell disease. Here we review the current understanding of the mechanism of action of epigenomic modifiers in the treatment of beta-thalassemia and sickle cell anemia. We also discuss how the lessons learned from the study of the effects of these compounds on the beta-globin locus, one of the best characterized regions of the human genome, might contribute to the understanding of the mechanism of action of these same compounds in cancer, where the specific regions of the genome that are responsible for the pathophysiology of the disease are often poorly defined.     

Pneumococcal pili are composed of protofilaments exposing adhesive clusters of Rrg A

Pili have been identified on the cell surface of Streptococcus pneumoniae, a major cause of morbidity and mortality worldwide. In contrast to Gram-negative bacteria, little is known about the structure of native pili in Gram-positive species and their role in pathogenicity. Triple immunoelectron microscopy of the elongated structure showed that purified pili contained RrgB as the major compound, followed by clustered RrgA and individual RrgC molecules on the pilus surface. The arrangement of gold particles displayed a uniform distribution of anti-RrgB antibodies along the whole pilus, forming a backbone structure. Antibodies against RrgA were found along the filament as particulate aggregates of 2-3 units, often co-localised with single RrgC subunits. Structural analysis using cryo electron microscopy and data obtained from freeze drying/metal shadowing technique showed that pili are oligomeric appendages formed by at least two protofilaments arranged in a coiled-coil, compact superstructure of various diameters. Using extracellular matrix proteins in an enzyme-linked immunosorbent assay, ancillary RrgA was identified as the major adhesin of the pilus. Combining the structural and functional data, a model emerges where the pilus RrgB backbone serves as a carrier for surface located adhesive clusters of RrgA that facilitates the interaction with the host.     

Novel uracil-based 2-aminoanilide and 2-aminoanilide-like derivatives: histone deacetylase inhibition and in-cell activities

A novel series of non-hydroxamate HDAC inhibitors (HDACi) showing a uracil group at the left and a 2-aminoanilide/2-aminoanilide-like portion at the right head have been reported. In particular, the new compounds incorporating a 2-aminoanilide moiety behaved as class I-selective HDACi. Compound 8, the most potent and class I-selective, showed weak apoptosis (higher than MS-275) joined to cytodifferentiating activity on U937 cells. Surprisingly, the highest differentiation was observed with 13, through an effect that seems to be unrelated to HDAC inhibition.