IL-22/STAT3-Induced Increases in SLURP1 Expression within Psoriatic Lesions Exerts Antimicrobial Effects against Staphylococcus aureus

Background

SLURP1 is the causal gene for Mal de Meleda (MDM), an autosomal recessive skin disorder characterized by diffuse palmoplantar keratoderma and transgressive keratosis. Moreover, although SLURP1 likely serves as an important proliferation/differentiation factor in keratinocytes, the possible relation between SLURP1 and other skin diseases, such as psoriasis and atopic dermatitis, has not been studied, and the pathophysiological control of SLURP1 expression in keratinocytes is largely unknown.

Objectives

Our aim was to examine the involvement of SLURP1 in the pathophysiology of psoriasis using an imiquimod (IMQ)-induced psoriasis model mice and normal human epidermal keratinocytes (NHEKs).

Results

SLURP1 expression was up-regulated in the skin of IMQ-induced psoriasis model mice. In NHEKs stimulated with the inflammatory cytokines IL-17, IL-22 and TNF-α, which are reportedly expressed in psoriatic lesions, SLURP1 mRNA expression was significantly up-regulated by IL-22 but not the other two cytokines. The stimulatory effect of IL-22 was completely suppressed in NHEKs treated with a STAT3 inhibitor or transfected with siRNA targeting STAT3. Because IL-22 induces production of antimicrobial proteins in epithelial cells, the antibacterial activity of SLURP1 was assessed against Staphylococcus aureus (S. aureus), which is known to be associated with disease severity in psoriasis. SLURP1 significantly suppressed the growth of S. aureus.

Conclusions

These results indicate SLURP1 participates in pathophysiology of psoriasis by regulating keratinocyte proliferation and differentiation, and by suppressing the growth of S. aureus.     

Definition of crucial structural factors of acetogenins, potent inhibitors of mitochondrial complex I

Some natural acetogenins are the most potent inhibitors of bovine heart mitochondrial complex I. These compounds are characterized by two functional units (i.e. hydroxylated tetrahydrofuran (THF) and alpha,beta-unsaturated gamma-lactone ring moieties) separated by a long alkyl spacer. To elucidate which structural factors of acetogenins including their active conformation are crucial for the potent inhibitory effect, we synthesized a series of novel acetogenin analogues possessing bis-THF rings. The present study clearly demonstrated that the natural gamma-lactone ring is not crucial for the potent inhibition, although this moiety is the most common structural unit among a large number of natural acetogenins and has been suggested to be the only reactive species that directly interacts with the enzyme (Shimada et al., Biochemistry 37 (1998) 854-866). The presence of free hydroxy group(s) in the adjacent bis-THF rings was favorable, but not essential, for the potent activity. This was probably because high polarity (or hydrophilicity), rather than hydrogen bond-donating ability, around the bis-THF rings is required to retain the inhibitor in the active conformation. Interestingly, length of the alkyl spacer proved to be a very important structural factor for the potent activity, the optimal length being approximately 13 carbon atoms. The present study provided further strong evidence for the previous proposal (Kuwabara et al., Eur. J. Biochem. 267 (2000) 2538-2546) that the gamma-lactone and THF ring moieties act in a cooperative manner on complex I with the support of some specific conformation of the spacer.     

Quantitative immunogold localization of Na, K-ATPase along rat nephron.

Ultrastructural localization of Na, K-ATPase alpha-subunit along rat nephron segments was investigated quantitatively by immunogold electron microscopy on LR-White ultrathin sections using affinity-purified antibody against alpha-subunit of the enzyme. Ultrathin sections were incubated with the antibody at a saturation level and the number of gold particles bound per micron of the plasma membrane (particle density) of the tubular epithelial cells from the proximal tubule to the collecting duct was determined. In all the tubular epithelial cells, gold particles were located exclusively on the basolateral surface, and no significant binding of gold particles to the apical surface was observed. Distribution of gold particles on the basolateral membranes was quite heterogeneous; lateral membranes and infolded basal membranes were highly labeled, whereas the basal membranes which are in direct contact with the basal lamina were scarcely labeled. The average particle density on the basal surface was highest in the distal straight tubule cells (11.4 units), very high in the distal convoluted tubule cells (9.8 units), intermediate in the proximal tubule cells (3.3 units), in the connecting tubule cells (4.3 units), and in the principal cells of the collecting duct (5.6-3.8 units), low in the thin limb of Henle's loop (1.0 unit), and at the control level in the intercalated cells in the connecting and collecting duct. The relative number of gold particles/mm nephron segment and the relative number of gold particles in the various nephron segments were calculated using quantitative morphological data. The estimated distribution profile of the former was in good agreement with the Na, K-ATPase activity profile in rat nephron, which was determined biochemically with a microenzymatic method.     

Dock8 interacts with Nck1 in mediating Schwann cell precursor migration

During embryonic development of the peripheral nervous system (PNS), Schwann cell precursors migrate along neuronal axons to their final destinations, where they will myelinate the axons after birth. While the intercellular signals controlling Schwann cell precursor migration are well studied, the intracellular signals controlling Schwann cell precursor migration remain elusive. Here, using a rat primary cell culture system, we show that Dock8, an atypical Dock180-related guanine-nucleotide exchange factor (GEF) for small GTPases of the Rho family, specifically interacts with Nck1, an adaptor protein composed only of Src homology (SH) domains, to promote Schwann cell precursor migration induced by platelet-derived growth factor (PDGF). Knockdown of Dock8 or Nck1 with its respective siRNA markedly decreases PDGF-induced cell migration, as well as Rho GTPase activation, in precursors. Dock8, through its unique N-terminal proline-rich motif, interacts with the SH3 domain of Nck1, but not with other adaptor proteins composed only of SH domains, e.g. Grb2 and CrkII, and not with the adaptor protein Elmo1. Reintroduction of the proline-rich motif mutant of Dock8 in Dock8 siRNA-transfected Schwann cell precursors fails to restore their migratory abilities, whereas that of wild-type Dock8 does restore these abilities. These results suggest that Nck1 interaction with Dock8 mediates PDGF-induced Schwann cell precursor migration, demonstrating not only that Nck1 and Dock8 are previously unanticipated intracellular signaling molecules involved in the regulation of Schwann cell precursor migration but also that Dock8 is among the genetically-conservative common interaction subset of Dock family proteins consisting only of SH domain adaptor proteins.     

Differential Responsiveness in Zonal Growth of Cocklebur Seed Axes to CO2, C2H4, O2 and Respiration Inhibitors

The axial growth of de-coated cocklebur (Xanthium pennsylvanicumWallr.) seeds, whose axes were divided into 4 zones, was examinedin relation to the temperature-dependent shift of the effectof C₂H₄ on germination. At 23?C, where both C₂H₄ and CO₂ stimulatedgermination, CO₂ promoted the axial growth at the radicle tipzone, whereas C₂H₄ promoted growth in the proximal portion ofthe axis. At 33?C, C₂H₄ inhibited germination, and stronglysuppressed the growth at the radicle tip, whereas the effectof CO₂ did not change. The inhibition of growth at the radicletip zone was alleviated by O₂ enrichment, which also reversedthe inhibition of germination. It is thus apparent that thetemperature-dependent shift of the action of C₂H₄ is associatedwith a temperature-dependent responsiveness of the radicle tipzone to C₂H₄. Growth of the radicle tip zone was sensitive toNaN₃, whereas the proximal portion was sensitive to benzohydroxamicacid, an inhibitor of alternative respiration, suggesting thatthere may be an increase in the operation of the alternativerespiration path along a gradient of axial tissue from the tiptowards the cotyledonary side. The effects of CO₂ and C₂H₄ arediscussed in relation to the different respiratory activitiesin each axial zone of cocklebur seeds. (Received May 9, 1986; Accepted November 6, 1986)     

Characterization of two cDNAs for novel drought-inducible genes in the highly drought-tolerant cowpea

Ten cDNAs for drought-inducible genes were isolated using differential screening of a cDNA library prepared from 10-hr dehydrated cowpea plants,Vigna unguiculata (S. Iuchi, K. Yamaguchi-Shinozaki, T. Urao, T. Terao, K. Shinozaki; Plant Cell Physiology, 1996 in press). Two of the cDNA clones, designated CPRD12 and CPRD46, were sequenced and characterized. The CPRD12 and CPRD46 cDNAs encode putative proteins related to nonmetallo-short-chain alcohol dehydrogenase (CPRD12) and chloroplastic lipoxygenase (CPRD46). Northern blot analysis revealed that these genes are induced by high-salinity stress and exogenous abscisic acid, but not by cold stress. The CPRD46 gene is also responsive to heat stress and methyl jasmonate and salicylic acid. Genomic Southern blot analysis suggested that CPRD12 constitutes a small gene family, but that CPRD46 is a single copy gene. We discuss the possible functions of these two CPRD gene products under drought stress.     

There are two major types of hepatitis C virus in Japan

The polymerase chain reaction (PCR) was used to detect hepatitis C virus (HCV) in plasma from chronic non-A, non-B hepatitis patients. By choice of adequate primers, 19 of 24 samples (79%) were found positive. Sequence analysis of amplified 400 bp cDNA fragments encoding a portion of NS5 gene suggested that HCV can be classified into two types (named K1 and K2) in Japan. Slot blot hybridization of the fragments indicated that 13 were HCV-K1 and 6 were HCV-K2, which show 80% and 67% nucleotide sequence homology, respectively, with that of the prototype.     

Illicit Drug Use Is a Significant Risk Factor for Loss to Follow Up in Patients with HIV-1 Infection at a Large Urban HIV Clinic in Tokyo

Background

Loss to follow up (LTFU) is an important prognostic factor in patients with HIV-1 infection. The impact of illicit drug use on LTFU of patients with HIV-1 infection is unknown in Japan.

Methods

A single center observational study was conducted to elucidate the impact of illicit drug use on LTFU at a large HIV clinic in Tokyo. LTFU was defined as those who discontinued their visits to the clinic for at least 12 months and were not known to be under the care of other facilities or have died within 12 months of their last visit. Patients who first visited the clinic between January 2005 and August 2010 were enrolled. Information on illicit drug use was collected in a structured interview and medical charts. Comparison of the effects of illicit drug use and no use on LTFU was conducted by uni- and multi-variate Cox hazards models as the primary exposure.

Results

The study subjects were 1,208 patients, mostly Japanese men, of relatively young age, and infected through homosexual contact. A total of 111 patients (9.2%) were LTFU (incidence: 24.9 per 1,000 person-years). Among illicit drug users and non users, 55 (13.3%) and 56 (7.1%) patients, respectively, were LTFU, with incidence of 35.7 and 19.2 per 1,000 person-years, respectively. Uni- and multi-variate analyses showed that illicit drug use was a significant risk for LTFU (HR=1.860; 95% CI, 1.282-2.699; p=0.001) (adjusted HR=1.544; 95% CI, 1.028-2.318; p=0.036). Multivariate analysis also identified young age, high CD4 count, no antiretroviral therapy, and no health insurance as risk factors for LTFU.

Conclusions

The incidence of LTFU among illicit drug users was almost twice higher than that among non users. Effective intervention for illicit drug use in this population is warranted to ensure proper treatment and prevent the spread of HIV.     

Effects of the combined substitutions of amino acid residues on thermal properties of cold-adapted monomeric isocitrate dehydrogenases from psychrophilic bacteria

In the two cold-adapted monomeric isocitrate dehydrogenases from psychrophilic bacteria, Colwellia maris and Colwellia psychrerythraea (CmIDH and CpIDH, respectively), the combined substitutions of amino acid residues between the Leu693, Leu724 and Phe735 residues of CmIDH and the corresponding Phe693, Gln724 and Leu735 residues of CpIDH were introduced by site-directed mutagenesis. A double mutant of CmIDH substituted its Leu724 and Phe735 residues by the corresponding ones of CpIDH, CmL724Q/F735L, and the triple mutant of CpIDH, CpF693L/Q724L/L735F, showed the most decrease and increase of activity, respectively, of each wild-type and its all mutated enzymes. In the case of CmIDH, the substitutions of these three amino acid residues resulted in the decrease of catalytic activity and thermostability for activity, but the combined substitutions of amino acid residues did not necessarily exert additive effects on these properties. On the other hand, similar substitutions in CpIDH had quite opposite effects to CmIDH, and the effects of the combined substitutions were additive. All multiple mutants of CmIDH and CpIDH showed lower and higher catalytic efficiency (k _cat/K _m) values than the respective wild-type enzymes. Single and multiple mutations of the substituted amino acid residues in the CmIDH and CpIDH led to the increase and decrease of sensitivity to tryptic digestion, indicating that the stability of protein structure was decreased and increased by the mutations, respectively.