A novel approach using functional peptides for efficient intestinal absorption of insulin.

The aim of this study was to evaluate whether oligoarginine, a cell-penetrating peptide (CPP), can improve intestinal absorption of insulin in rats. Peptides composed of six (R(6)), eight (R(8)) and 10 (R(10)) residues of arginine were used as the CPP. No insulin absorption was observed following administration of insulin solution alone; however, insulin absorption increased dramatically after coadministration of the D-form of R(6) (D-R(6)) and the L-form of R(6) (L-R(6)) in a dose-dependent manner. The effects on insulin absorption were more pronounced for D-R(6) than for L-R(6). Among oligoarginines composed of six, eight, or 10 arginine residues, D-R(8) showed the strongest enhancing effects on insulin intestinal absorption. In contrast, intestinal absorption of other model hydrophilic macromolecules, interferon-beta and fluorescein isothiocyanate-labeled dextran 4400, was not affected by coadministration with oligoarginine. Pretreatment by the effective dose of L-R(6) did not induce lactate dehydrogenase leakage or histological damage, suggesting that oligoarginine has no untoward effect on the intestinal mucosa. Our data demonstrate that coadministration of oligoarginine increases intestinal insulin absorption markedly without causing detectable damage in cellular integrity and that the covalent binding between insulin and oligoarginine is not necessary for this effect. We conclude that oligoarginines are likely to become powerful tools for overcoming the low permeability of insulin through the epithelial cell membrane, the major barrier to oral insulin delivery.     

Mouthguards for a childhood hypophosphatasia patient to protect periodontal tissue of immature permanent teeth – Case report

Hypophosphatasia (HPP) is an inherited skeletal disorder that features early exfoliation of primary teeth as a major dental manifestation. A 6Y4M Japanese girl diagnosed with childhood HPP came to our clinic. Deep probing depth for all teeth and severe mobility of primary incisors were observed. At 7Y1M, the mandibular central incisors received a traumatic injury, with no treatment performed and slight mobility observed thereafter. Such traumatic injuries were repeated, thus mouthguards (MGs) to protect weak periodontal tissue were applied, which helped to maintain stable conditions. Use of a MG may be helpful for HPP patients.     

Novel Virulent Bacteriophage ΦSG005, Which Infects Streptococcus gordonii,Forms a Distinct Clade among Streptococcus Viruses

Bacteriophages are viruses that specifically infect bacteria and are classified as either virulent phages or temperate phages. Despite virulent phages being promising antimicrobial agents due to their bactericidal effects, the implementation of phage therapy depends on the availability of virulent phages against target bacteria. Notably, virulent phages of Streptococcus gordonii, which resides in the oral cavity and is an opportunistic pathogen that can cause periodontitis and endocarditis have previously never been found. We thus attempted to isolate virulent phages against S. gordonii. In the present study, we report for the first time a virulent bacteriophage against S. gordonii, ΦSG005, discovered from drainage water. ΦSG005 is composed of a short, non-contractile tail and a long head, revealing Podoviridae characteristics via electron microscopic analysis. In turbidity reduction assays, ΦSG005 showed efficient bactericidal effects on S. gordonii. Whole-genome sequencing showed that the virus has a DNA genome of 16,127 bp with 21 coding sequences. We identified no prophage-related elements such as integrase in the ΦSG005 genome, demonstrating that the virus is a virulent phage. Phylogenetic analysis indicated that ΦSG005 forms a distinct clade among the streptococcus viruses and is positioned next to streptococcus virus C1. Molecular characterization revealed the presence of an anti-CRISPR (Acr) IIA5-like protein in the ΦSG005 genome. These findings facilitate our understanding of streptococcus viruses and advance the development of phage therapy against S. gordonii infection.     

TAK1 is a pivotal therapeutic target for tumor progression and bone destruction in myeloma

Along with tumor progression, the bone marrow microenvironment is skewed in multiple myeloma (MM), which underlies the unique pathophysiology of MM and confers aggressiveness and drug resistance in MM cells. TGF-b-activated kinase-1 (TAK1) mediates a wide range of intracellular signaling pathways. We demonstrate here that TAK1 is constitutively overexpressed and phosphorylated in MM cells, and that TAK1 inhibition suppresses the activation of NF-κB, p38MAPK, ERK and STAT3 in order to decrease the expression of critical mediators for MM growth and survival, including PIM2, MYC, Mcl- 1, IRF4, and Sp1, along with a substantial reduction in the angiogenic factor VEGF in MM cells. Intriguingly, TAK1 phosphorylation was also induced along with upregulation of vascular cell adhesion molecule-1 (VCAM-1) in bone marrow stromal cells (BMSC) in cocultures with MM cells, which facilitated MM cell-BMSC adhesion while inducing IL-6 production and receptor activator of nuclear factor κ-B ligand (RANKL) expression by BMSC. TAK1 inhibition effectively impaired MM cell adhesion to BMSC to disrupt the support of MM cell growth and survival by BMSC. Furthermore, TAK1 inhibition suppressed osteoclastogenesis enhanced by RANKL in cocultures of bone marrow cells with MM cells, and restored osteoblastic differentiation suppressed by MM cells or inhibitory factors for osteoblastogenesis overproduced in MM. Finally, treatment with the TAK1 inhibitor LLZ1640-2 markedly suppressed MM tumor growth and prevented bone destruction and loss in mouse MM models. Therefore, TAK1 inhibition may be a promising therapeutic option targeting not only MM cells but also the skewed bone marrow microenvironment in MM.     

Insulin-independent and wortmannin-resistant targeting of IRS-3 to the plasma membrane via its pleckstrin homology domain mediates a different interaction with the insulin receptor from that of IRS-1

Aims/hypothesis: In primary adipocytes, although IRS-1 and IRS-3 are expressed in comparable amounts, these proteins manifest distinct distribution and significance in insulin signalling. We investigated the molecular basis of the difference between these two proteins. Methods: In Cos-1 cells transiently expressing rat IRS-1, IRS-3, or chimeric proteins of these two proteins we examined the tyrosine phosphorylation via the wild-type or mutant insulin receptors and evaluated their targeting to the plasma membrane by immunostaining the membrane ghost. Results: In contrast to IRS-1, IRS-3 was tyrosine-phosphorylated by the insulin receptor altering Tyr⁹⁶⁰ to Phe (Y960F), which disrupts the binding site of the PTB domain of IRSs, to an extent comparable to the wild-type receptor. The tyrosine phosphorylation of IRS-3 with the PH domain replacement via the Y960F insulin receptor markedly decreased, whereas that of IRS-3 with the PTB domain alteration was mildly impaired. Insulin-stimulated translocation of IRS-1 to the plasma membrane, as well as that of IRS-3 with the PH domain replacement, was wortmannin-sensitive, although that of IRS-3 was insulin-independent and wortmannin-resistant. Conclusions/interpretation: The affinity of the PH domain for the phospholipids in the plasma membrane seems to influence the receptor-substrate interaction required for IRS tyrosine phosphorylation, indicating that the PH domain and the PTB domain of IRSs cooperatively function in insulin-stimulated tyrosine phosphorylation of these proteins. [Diabetologia (2001) 44: 992–1004] Received: 17 October 2000 and in revised form: 27 March 2001