Report of the 13th Annual International Pachyonychia Congenita Consortium Symposium.

The International Pachyonychia Congenita Consortium (IPCC) is a group of physicians and scientists from around the world dedicated to developing therapies for pachyonychia congenita, a rare autosomal dominant skin disorder. The research presented at the 13th Annual Research Symposium of the IPCC, held on 10-11 May 2016, in Scottsdale, AZ, U.S.A., is reported here.

Pachyonychia congenita cornered: report on the 11th Annual International Pachyonychia Congenita Consortium Meeting.

This is a report of the research presented at the 11th Annual Meeting of the International Pachyonychia Congenita Consortium, held on 6 May 2014 in Albuquerque, NM, U.S.A. This year's meeting was divided into five corners concerning pachyonychia congenita (PC) research: (i) 'PC Pathogenesis Cornered', an overview of recent keratin research, for PC and other skin disorders; (ii) 'From All Corners of …', an outline of other genetic disorders that we can learn from; (iii) 'Fighting For Our Corner', an outline of National Institutes of Health/National Institute of Arthritis and Musculoskeletal and Skin Diseases programmes and U.S. funding opportunities applicable to rare skin disorders; (iv) 'The PC Corner', focusing on recent clinical studies related to PC; and (v) 'Clinical Corners: Turning the Corner?', an update on ongoing PC clinical trials.

Increased interstitial pressure improves nucleic acid delivery to skin enabling a comparative analysis of constitutive promoters.

Nucleic acid-based therapies hold great promise for treatment of skin disorders if delivery challenges can be overcome. To investigate one mechanism of nucleic acid delivery to keratinocytes, a fixed mass of expression plasmid was intradermally injected into mouse footpads in different volumes, and reporter expression was monitored by intravital imaging or skin sectioning. Reporter gene expression increased with higher delivery volumes, suggesting that pressure drives nucleic acid uptake into cells after intradermal injections similar to previously published studies for muscle and liver. For spatiotemporal analysis of reporter gene expression, a dual-axis confocal (DAC) fluorescence microscope was used for intravital imaging following intradermal injections. Individual keratinocytes expressing hMGFP were readily visualized in vivo and initially appeared to preferentially express in the stratum granulosum and subsequently migrate to the stratum corneum over time. Fluorescence microscopy of frozen skin sections confirmed the patterns observed by intravital imaging. Intravital imaging with the DAC microscope is a noninvasive method for probing spatiotemporal control of gene expression and should facilitate development and testing of new nucleic acid delivery technologies.

Therapeutic silencing of an endogenous gene by siRNA cream in an arthritis model mouse.

Recent advances of biotechnology have laid the groundwork for potent and specific molecular-targeting therapies including RNA interference. The largest remaining hurdle for widespread use of this technology in skin is an effective delivery system. Here, we demonstrate an effective topical delivery system using a cream formulation containing a small-interfering RNA (siRNA) that specifically targets osteopontin (OPN). OPN is a validated target in numerous inflammatory diseases, including rheumatoid arthritis (RA). The siRNA targeting OPN was incorporated into a cream formulation GeneCream that penetrates the stratum corneum, depositing siRNA in the epidermis, dermis, and to a lesser extent, subcutaneous tissue. In addition, when the OPN siRNA cream was topically applied to the skin of a collagen antibody-induced RA mouse model, the siRNA cream prevented the occurrence of severe, irreversible damage to bone and cartilage. Thus, the siRNA cream provides effective delivery of active OPN siRNA, suggesting this formulation may represent a platform technology for delivery of siRNAs for treating various disorders including RA.

siRNA silencing of keratinocyte-specific GFP expression in a transgenic mouse skin model.

Small interfering RNAs (siRNAs) can be designed to specifically and potently target and silence a mutant allele, with little or no effect on the corresponding wild-type allele expression, presenting an opportunity for therapeutic intervention. Although several siRNAs have entered clinical trials, the development of siRNA therapeutics as a new drug class will require the development of improved delivery technologies. In this study, a reporter mouse model (transgenic click beetle luciferase/humanized monster green fluorescent protein) was developed to enable the study of siRNA delivery to skin; in this transgenic mouse, green fluorescent protein reporter gene expression is confined to the epidermis. Intradermal injection of siRNAs targeting the reporter gene resulted in marked reduction of green fluorescent protein expression in the localized treatment areas as measured by histology, real-time quantitative polymerase chain reaction and intravital imaging using a dual-axes confocal fluorescence microscope. These results indicate that this transgenic mouse skin model, coupled with in vivo imaging, will be useful for development of efficient and 'patient-friendly' siRNA delivery techniques and should facilitate the translation of siRNA-based therapeutics to the clinic for treatment of skin disorders.

Binding of the La autoantigen to the 5' untranslated region of a chimeric human translation elongation factor 1A reporter mRNA inhibits translation in vitro.

Human translation elongation factor 1A (EF1A) is a member of a large class of mRNAs, including ribosomal proteins and other translation elongation factors, which are coordinately translationally regulated under various conditions. Each of these mRNAs contains a terminal oligopyrimidine tract (TOP) that is required for translational control. A human growth hormone (hGH) expression construct containing the promoter region and 5' untranslated region (UTR) of EF1A linked to the hGH coding region (EF1A/hGH) was translationally repressed following rapamycin treatment in similar fashion to endogenous EF1A in human B lymphocytes. Mutation of two nucleotides in the TOP motif abolished the translational regulation. Gel mobility shift assays showed that both La protein from human B lymphocyte cytoplasmic extracts as well as purified recombinant La protein specifically bind to an in vitro-synthesized RNA containing the 5' UTR of EF1A mRNA. Moreover, extracts prepared from rapamycin-treated cells showed increased binding activity to the EF1A 5' UTR RNA, which correlates with TOP mRNA translational repression. In an in vitro translation system, recombinant La dramatically decreased the expression of EF1A/hGH construct mRNA, but not mRNAs lacking an intact TOP element. These results indicate that TOP mRNA translation may be modulated through La binding to the TOP element.

Selection of cleavage site by mammalian tRNA 3' processing endoribonuclease.

Mammalian tRNA 3' processing endoribonuclease (3' tRNase) removes 3' trailers from pre-tRNAs by cleaving the RNA immediately downstream of the discriminator nucleotide. Although 3' tRNase can recognize and cleave any target RNA that forms a pre-tRNA-like complex with another RNA, in some cases cleavage occurs at multiple sites near the discriminator. We investigated what features of pre-tRNA determine the cleavage site using various pre-tRNAArg variants and purified pig enzyme. Because the T stem-loop and the acceptor stem plus a 3' trailer are sufficient for recognition by 3' tRNase, we constructed variants that had additions and/or deletions of base-pairs in the T stem and/or the acceptor stem. Pre-tRNAs lacking one and two acceptor stem base-pairs were cleaved one and two nucleotides and two and three nucleotides, respectively, downstream of the discriminator. On the other hand, pre-tRNA variants containing extra acceptor stem base-pairs were cleaved only after the discriminator. The cleavage site was shifted to one and two nucleotides downstream of the discriminator by deleting one base-pair from the T stem, but was not changed by additional base-pairs in the T stem. Pre-tRNA variants that contained an eight base-pair acceptor stem plus a six base-pair T stem, an eight base-pair acceptor stem plus a four base-pair T stem, or a six base-pair acceptor stem plus a six base-pair T stem were all cleaved after the original nucleotide. In general, pre-tRNA variants containing a total of more than 11 bp in the acceptor stem and the T stem were cleaved only after the discriminator, and pre-tRNA variants with a total of N bp (N is less than 12) were cleaved 12-N and 13-N nt downstream of the discriminator. Cleavage efficiency of the variants decreased depending on the degree of structural changes from the authentic pre-tRNA. This suggests that the numbers of base-pairs of both the acceptor stem and the T stem are important for recognition and cleavage by 3' tRNase.

The inhibitory effect of the autoantigen La on in vitro 3' processing of mammalian precursor tRNAs.

Mammalian tRNA 3' processing endoribonuclease (3' tRNase) can remove a 3' trailer from various precursor (pre)-tRNAs. We investigated what effect the autoantigen La has on 3' processing, since the La protein is known to bind to a 3'-terminal uridine tract of pre-tRNAs. We tested sixteen different pre-tRNA(Arg) substrates containing various 3' trailers with or without a 5' leader sequence for in vitro processing by pig 3' tRNase, and for gel-retardation in the presence or absence of human La protein. The R-TUUU series consists of four pre-tRNAs containing 6, 8, 11 and 15 nt 3' trailers ending with UUU and no 5' leader, while the R-TAGC series consists of the same four pre-tRNAs as R-TUUU except that the terminal sequence is AGC. The R-6LTUUU and R-6LTAGC series are derived from R-TUUU and R-TAGC, respectively, by adding a 6 nt 5' leader. La differentially inhibited their processing and bound to the pre-tRNAs; the 50 % inhibitory concentrations for the R-TUUU, R-TAGC, R-6LTUUU, and R-6LTAGC series were 82 to >850, >850, 2 to 292 and 573 to 785 nM, respectively, and the dissociation constants were 10 to 840, >850, 3 to 203 and 155 to 520 nM, respectively. These results indicate that both the terminal sequence UUU and the 5' leader contribute to more severe inhibition of 3' processing via tighter interaction with La. With respect to the R-TUUU and R-6LTUUU series, on the whole, the La inhibition was enhanced as the 3' trailer lengths decreased. Taken together, our results suggest that the La protein sterically hinders 3' tRNase from binding a pre-tRNA molecule probably near the cleavage site.

Amikacin therapy of patients with multiply antibiotic-resistant Serratia marcescens infections: development of increasing resistance during therapy.

Over a recent 22 month period, 222 patients in two adjacent hospitals became infected with a multiply antibiotic-resistant strain of Serratia marcescens; 13 were bacteremic. Nineteen patients with clinically significant infections received amikacin. Nine of 11 patients with urinary tract infections were cured. In contrast, only one of eight patients with pneumonia or other deep tissue infections was cured and four died. These eight patients were severely ill; many had infections with multiple microorganisms. In four of five patients in whom the infection failed to clear promptly. Serratia strains became increasingly resistant to amikacin during therapy and these strains contributed to the death of two of these patients. Amikacin proved useful in treating patients with infections due to gentamicin-resistant S. marcescens organisms, especially urinary tract infections. However, the capacity of some strains of S. marcescens to develop resistance to amikacin may limit the usefulness of this antibiotic in the treatment of deep tissue infections which involve this microorganism.

Tumor necrosis factor and lymphotoxin: protection against oxidative stress through induction of MnSOD.

Tumor necrosis factor (TNF) and lymphotoxin (LT) are related cytokines produced in response to infection or oxidative insults such as radiation. These cytokines bind to the same receptors and have pleiotropic effects on a variety of cell types. TNF or LT pretreatment, which can induce the synthesis of "protective" proteins such as mitochondrial manganese superoxide dismutase (MnSOD), protects animals from lethal doses of radiation or the chemotherapeutic drug doxorubicin. In contrast, TNF or LT pretreatment of tumor cells, which do not express MnSOD, results in sensitization to these insults. Therefore, radio- or chemoprotection of normal cells may act partially through enhanced expression of MnSOD. On the other hand, tumor sensitization may result from activation of "killing" proteins such as interleukin-1 beta converting enzyme (ICE) or other ICE-like proteases, possibly through TNF/LT-induced oxygen free radicals. In addition to their originally described anti-tumor activity, these cytokines may have new therapeutic indications in protecting normal cells while sensitizing tumor cells to radiation or chemotherapeutic drugs.

Purification and physical analysis of Bacillus anthracis plasmids pXO1 and pXO2.

Virulent strains of Bacillus anthracis contain two large plasmids. pXO1 encodes the three component protein exotoxin and pXO2 is necessary for synthesis of the poly-D-glutamic acid capsule. A procedure for the isolation of these plasmids which yields high quantities of pure DNA is described. Restriction endonuclease analysis of these plasmids shows that they are not related. pXO1 is 174 kilobase pairs and pXO2 is 95 kilobase pairs. From their bouyant densities and melting temperatures we also determined their GC contents. pXO1 contains 31.1% GC base pairs and pXO2 is 31.4% GC. Both of these values are close to the GC content of B. anthracis genomic DNA which is 32.2%.

Perihepatitis and hepatitis as complications of experimental endocarditis due to Neisseria gonorrhoeae in the rabbit.

Seven strains of Neisseria gonorrhoeae (colony type 1 or 2) were tested for their ability to produce endocarditis in rabbits with transaortic valve catheters. The gonococci exhibited three auxotype patterns and a broad range of susceptibility to penicillin and to complement-mediated serum bactericidal activity. Only four strains produced endocarditis; infectivity appeared to be related to serum resistance. Neither arthritis nor skin lesions were observed in infected animals, but 40% had hepatitis, often with fibrinous perihepatitis. Hepatic lesions could be induced by the continuous infusion of gonococci without a transvalvular catheter. Suppurative hepatitis in the rabbit endocarditis model is of particular interest in light of the unusual hepatic involvement reported in association with gonococcal endocarditis in humans. Since perihepatitis also occurs as a complication of experimental gonococcal bacteremia, perhaps the Fitz-Hugh-Curtis (gonococcal perihepatitis) syndrome appearing in women occurs more often as a function of undiagnosed bacteremia than has heretofore been suspected.

Rapid, simple bioassay for 5-fluorocytosine in the presence of amphotericin B.

It is important that serum levels of 5-fluorocytosine (5FC) be measured to insure therapeutic levels while avoiding toxicity. This is particularly true in patients with renal insufficiency. The concurrent use of amphotericin B and 5FC complicates the measurement of 5FC in the serum, since fungi used in conventional bioassay systems are uniformly susceptible to amphotericin B. This paper describes the development of a simple, reliable, 6-h bioassay for 5FC in the presence of amphotericin B. The assay is based upon the fact that 5FC diffuses readily through yeast nitrogen base agar, whereas amphotericin B apparently does not. This assay allows rapid adjustments in therapy of patients receiving both 5FC and amphotericin B and has permitted us to maintain 5FC serum levels between limits of 25 and 120 mug/ml in patients with altered renal function.

Peripheral blood mononuclear cells stimulated with C5a or lipopolysaccharide to synthesize equivalent levels of IL-1 beta mRNA show unequal IL-1 beta protein accumulation but similar polyribosome profiles.

Recent reports suggest that regulation of IL-1 beta gene expression in human monocytes may include translation level as well as transcription level control mechanisms. We studied IL-1 beta expression in PBMC stimulated with recombinant complement protein C5a or with LPS. IL-1 beta mRNA was expressed by C5a-treated PBMC, but very little or no IL-1 beta protein could be detected by ELISA or by Western blot analysis using a polyclonal Ab that reacts equally with pro-IL-1 beta and processed mature IL-1 beta. LPS-treated cells produced both IL-1 beta mRNA and protein. Velocity sedimentation analysis revealed, however, that IL-1 beta mRNA assembles into large polyribosomes in both C5a- and LPS-treated cells. Translation of the IL-1 beta mRNA in C5a-treated cells is not therefore blocked at the level of protein synthesis initiation. IL-1 beta mRNA was released from polyribosomes by treating the cells with puromycin, suggesting that the ribosomes are not frozen at the elongation phase of protein synthesis. One explanation for the data is that the rate of IL-1 beta polypeptide chain elongation or termination may be diminished in the C5a-stimulated PBMC.

Minimum requirements for substrates of mammalian tRNA 3' processing endoribonuclease.

Mammalian tRNA 3' processing endoribonuclease (3' tRNase) removes a 3' trailer after the discriminator nucleotide from precursor tRNA (pre-tRNA). To elucidate the minimum requirements for 3' tRNase substrates, we tested small pre-tRNA(Arg) substrates lacking the D and anticodon stem-loop domain for cleavage by purified pig 3' tRNase. A small pre-tRNA (R-ATW) composed of an acceptor stem, an extra loop, a T stem-loop domain, a discriminator nucleotide, and a 3' trailer was cleaved more efficiently than the full-length wild type. The catalytic efficiencies of three R-ATW derivatives, which were constructed to destroy the original T stem base pairs, were also higher than that of the full-length wild type. Pig 3' tRNase efficiently processed a "minihelix" (R-ATM5) that consists of a T stem-loop domain, an acceptor stem, a discriminator nucleotide, and a 3' trailer, while the enzyme never cleaved a "microhelix" that is composed of a T loop, an acceptor stem, a discriminator nucleotide, and a 3' trailer. Five R-ATM5 derivatives that have one to seven base substitutions in the T loop were all cleaved slightly more efficiently than the full-length wild type and slightly less efficiently than R-ATM5. A helix ("minihelixDelta1") one base pair smaller than minihelices was a good substrate, while small helices containing a continuous 10-base pair stem were poor substrates. The cleavage of these three small substrates occurred after the discriminator and one to three nucleotides downstream of the discriminator. From these results, we conclude that minimum substrates for efficient cleavage by mammalian 3' tRNase are minihelices or minihelicesDelta1, in which there seem to be no essential bases.

A simple method for diagnosing pneumonia in intubated or tracheostomized patients.

A safe, simple, reliable technique for sampling uncontaminated peripheral bronchial secretions in patients with endotracheal tubes has been developed. It is easily performed and requires no special training or equipment. This report summarizes the techniques's usefulness in providing diagnostic samples of peripheral airway secretions from 20 patients with pneumonic infiltrates. In eight of the patients, a single organism was recovered from the peripheral airway despite polymicrobial colonization of the upper airways. An additional patient had two anaerobes. The recovered organism's role as a pathogen was verified by an appropriate response to specific antibiotic therapy in two patients, isolation from blood or empyema fluid in five, confirmation by bronchoscopy in one, and transtracheal aspiration after extubation in one. Peripheral bronchial secretions were sterile in the remaining 11 patients, even though multiple organsims were isolated from usual tracheal suctionings.

Long 5' leaders inhibit removal of a 3' trailer from a precursor tRNA by mammalian tRNA 3' processing endoribonuclease.

Mammalian tRNA 3' processing endoribonuclease (3' tRNase) can remove a 3' trailer from various pre-tRNAs without 5' leader nucleotides. To examine how 5[prime] leader sequences affect 3' processing efficiency, we performed in vitro 3' processing reactions with purified pig 3' tRNase and pre-tRNAArgs containing a 13-nt 3' trailer and a 5[prime] leader of various lengths. The 3' processing was slightly stimulated by 5[prime] leaders containing up to 7 nt, whereas leaders of 9 nt or longer severely inhibited the reaction. Structure probing indicated that the 5' leader sequences had little effect on pre-tRNA folding. Similar results were obtained using pre-tRNA(Val)s containing a 5' leader of various lengths. We also investigated whether 3'tRNase can remove 3' trailers that are stably base-paired with 5' leaders to form an extended acceptor stem. Even such small 5' leaders as 3 and 6 nt, when base-paired with a 3' trailer, severely hindered removal of the 3' trailer by 3' tRNase.

Simultaneous cytoplasmic redistribution of ribosomal protein L32 mRNA and phosphorylation of eukaryotic initiation factor 4E after mitogenic stimulation of Swiss 3T3 cells.

Ribosomal protein L32 mRNA moved from messenger ribonucleoprotein particles into polysomes following serum activation of quiescent Swiss 3T3 cells. This redistribution of the mRNA into a translationally active state began by 1 h and was complete by 3 h after activation. In contrast, actin mRNA showed no translational control, being found predominantly in polysomes in both quiescent and activated cultures. The phosphorylation state of eukaryotic initiation factor (eIF) 4E, which binds mRNA caps, was examined in parallel. eIF-4E phosphorylation was elevated by 1 h following serum activation and reached a peak by 3-5 h. Treatment of resting cells with phorbol ester also simultaneously stimulated eIF-4E phosphorylation and the movement of L32 mRNA into polysomes. These results are consistent with a model in which mitogen-induced phosphorylation increases the pool of active eIF-4E molecules, which in turn cause the recruitment of translationally controlled mRNAs to actively synthesizing ribosomes.

A regulatory cis element and a specific binding factor involved in the mitogenic control of murine ribosomal protein L32 translation.

The mRNA encoding ribosomal protein L32 redistributes from untranslated subribosomal particles into polysomes after mitogenic activation of quiescent T-lymphocytes and fibroblasts. To identify the regions of the L32 mRNA which are important in regulating its cytoplasmic location we constructed a plasmid containing the murine L32 cDNA under the control of the Rous sarcoma virus (RSV) long terminal repeat promoter and introduced this construct into murine 3T3 fibroblasts. The mRNA transcribed from the RSV-L32 construct redistributed from subribosomal particles into polysomes in response to mitogenic activation in a manner similar to endogenous L32 mRNA. A conserved polypyrimidine region present at the 5' terminus of all ribosomal protein mRNAs is required for translational regulation of L32 mRNA since deletion of this sequence resulted in a mRNA that was not sequestered in subribosomal particles in quiescent cells. A radioactive RNA probe containing the first 34 nucleotides of the L32 5'-untranslated region, including the polypyrimidine region, specifically interacted with a protein of about 56 kDa. This protein did not bind detectably to RNA probes lacking the polypyrimidine sequence. Binding activity was similar in protein extracts made from resting and activated cells, suggesting that binding of the 56-kDa protein as measured in this assay is not regulated. This protein is a member of what may be an emerging family of polyribopyrimidine-binding proteins with diverse biochemical functions.