Genomes of complex viruses have been demonstrated, in many cases, to be packaged into preformed empty capsids (procapsids). This reaction is performed by molecular motors translocating nucleic acid against the concentration gradient at the expense of NTP hydrolysis. At present, the molecular mechanisms of packaging remain elusive due to the complex nature of packaging motors. In the case of the double-stranded RNA bacteriophage phi 6 from the Cystoviridae family, packaging of single-stranded genomic precursors requires a hexameric NTPase, P4. In the present study, the purified P4 proteins from two other cystoviruses, phi 8 and phi 13, were characterized and compared with phi 6 P4. All three proteins are hexameric, single-stranded RNA-stimulated NTPases with alpha/beta folds. Using a direct motor assay, we found that phi 8 and phi 13 P4 hexamers translocate 5' to 3' along ssRNA, whereas the analogous activity of phi 6 P4 requires association with the procapsid. This difference is explained by the intrinsically high affinity of phi 8 and phi 13 P4s for nucleic acids. The unidirectional translocation results in RNA helicase activity. Thus, P4 proteins of Cystoviridae exhibit extensive similarity to hexameric helicases and are simple models for studying viral packaging motor mechanisms.

beta-Secretase (BACE) is a membrane-bound aspartyl protease that cleaves the amyloid precursor protein to generate the N terminus of the amyloid beta peptide. BACE is expressed as a precursor protein containing Pre, Pro, protease, transmembrane, and cytosolic domains. A soluble BACE derivative (PreProBACE460) that is truncated between the protease and transmembrane domains was produced by baculovirus-mediated expression. ProBACE460 was purified from conditioned media of infected insect cells using immobilized concanavalin A and immobilized BACE inhibitor, P10-P4' Stat(Val). Furin cleaves ProBACE460 between the Pro and protease regions to generate mature BACE460. The k(cat)/K(m) of ProBACE460 when assayed with a polypeptide substrate is only 2.3-fold less than that of BACE460. This finding and the similar inhibitory potency of P10-P4' Stat(Val) for ProBACE460 and BACE460 suggest that the Pro domain has little effect on the BACE active site. Exposure of ProBACE460 to guanidine denaturation/renaturation results in a 7-fold higher recovery of BACE activity than when BACE460 is similarly treated. The presence of free BACE Pro peptide during renaturation of BACE460 but not ProBACE460 increases recovery of activity. These findings show that the Pro domain in ProBACE460 does not suppress activity as in a strict zymogen but does appear to facilitate proper folding of an active protease domain.

Injection of inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4) into voltage-clamped oocytes of Xenopus laevis elicited an oscillatory chloride membrane current. This response did not depend upon extracellular calcium, because it could be produced in calcium-free solution and after addition of cobalt to block calcium channels in the surface membrane. However, it was abolished after intracellular loading with the calcium chelating agent EGTA, indicating a dependence upon intracellular calcium. The mean dose of Ins(1,3,4,5)P4 required to elicit a threshold current was 4 x 10(-14) mol. In comparison, inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) gave a similar oscillatory current with doses of about one twentieth as big. Hyperpolarization of the oocyte membrane during activation by Ins(1,3,4,5)P4 elicited a transient inward current, as a result of the opening of calcium-dependent chloride channels subsequent to the entry of external calcium. In some oocytes the injection of Ins(1,3,4,5)P4 was itself sufficient to allow the generation of the transient inward current, whereas in others a prior injection of Ins(1,4,5)P3 was required. We conclude that Ins(1,3,4,5)P4 causes the release of intracellular calcium from stores in the oocyte, albeit with less potency than Ins(1,4,5)P3. In addition, Ins(1,3,4,5)P4 activates voltage-sensitive calcium channels in the surface membrane, via a process that may require 'priming' by Ins(1,4,5)P3.

Recent studies have identified a multi-component receptor system for the neurotrophic factor, glial cell line-derived neurotrophic factor (GDNF) and its homolog, neurturin (NTN), comprising the signaling tyrosine kinase, Ret and multiple GPI-linked binding proteins, GDNF family receptor alpha-1 and alpha-2 (GFRalpha-1 and GFRalpha-2). In the present study the localization of c-ret and GFRalpha-1 and GFRalpha-2 mRNAs was assessed in the developing rat brain from postnatal day 4 to 70 by in situ hybridization histochemistry, using specific [35S]-labeled oligonucleotides. GFRalpha-1 and GFRalpha-2 mRNAs were differentially distributed throughout the brain at all ages studied, particularly in cerebral cortex, hippocampus, substantia nigra and regions of the thalamus and hypothalamus - both distributions overlapping but different to that of c-ret mRNA. C-ret mRNA was abundant in areas such as the lateral habenula, reticular thalamic nucleus, substantia nigra pars compacta, cranial motor nuclei, and the Purkinje cell layer of the cerebellum. GFRalpha-1 mRNA was abundant in dorsal endopiriform nucleus, medial habenula, reticular thalamic nucleus, pyramidal and granule cell layers of the hippocampus, substantia nigra pars compacta and in cranial motor nuclei. GFRalpha-2 mRNA was highly expressed in many regions including olfactory bulb, lateral olfactory tract nucleus, neocortical layers IV and VI, septum, zona incerta, and arcuate and interpeduncular nuclei. GFRalpha-2 mRNA was detected in the pyramidal cell layers (CA3) of hippocampus at P4 and P7, but was no longer detectable at P14 and beyond, including P70 (adult). GFRalpha-2 mRNA was also detected in Purkinje cells throughout the cerebellum in young postnatal rats, but was enriched in the posterior lobes at P28 and P70. These localization studies support evidence of GDNF/NTN as target-derived and autocrine/paracrine trophic factors in developing brain pathways and earlier suggestions of unique and complex signaling mechanisms for these factors via a family of receptors. Strong expression of GFRalpha-1 and GFRalpha-2 mRNAs in adult brain suggests possible non-trophic functions of GDNF/NTN, as described for other neurotrophins, such as brain-derived neurotrophic factor.

Epilepsy is an intractable disease, though many treatment modalities have been developed. Recently, noninvasive transcranial direct current stimulation (tDCS), which can change brain excitability, was introduced and has been applied for therapeutic purposes regarding epilepsy. A suppression of seizures was experienced by cathodal tDCS in a medication refractory pediatric epileptic patient. The patient was an 11-year-old female who had focal cortical dysplasia of the cerebral hemisphere. The patient was treated with antiepileptic drugs but the mean seizure frequency was still eight episodes per month. The tDCS cathode was placed at the midpoint of P4 and T4 in the 10-20 EEG system where the abnormal wave was observed on a sleep EEG. Two mA of tDCS was applied 20 minutes a day, five days a week for two weeks. During a two-month period after treatment termination, only six seizure attacks occurred, and the duration of each seizure episode also decreased. tDCS was applied under the same conditions for another two weeks. For two months after the second treatment session, only one seizure attack occurred, and it showed great improvement compared to the eight seizure attacks per month before the tDCS treatment. The medications were not changed, and there were no notable side effects that were caused by tDCS.

OBJECTIVE

Seizure exacerbation in catamenial epilepsy (CE) is associated with the decrease in progesterone secretion and increase in estradiol secretion during the premenstrual period. Moreover, experimental evidence suggests that tetrahydrodeoxycorticosterone (THDOC), a positive modulator of the type A receptor for gamma-aminobutyric acid (GABA), and dehydroepiandrosterone sulfate (DHEAS), a negative modulator of this receptor, might play a crucial role in modulating seizure frequency during the menstrual cycle. Following these studies it seems of interest to investigate possible variations, among other hormonal parameters, of THDOC and DHEAS in CE patients.

METHODS

The serum concentrations of progesterone (P4), pregnenolone, allopregnanolone (AP), THDOC, DHEAS, cortisol, and DHEAS/cortisol ratio were measured throughout the menstrual cycle at the 7th, 11th, 15th, 19th, 23rd, and 27th day from the onset of spontaneous menstrual blood loss in young premenopausal women with CE (n = 17) and age-matched controls (n = 13).

RESULTS

At each time of the study, the serum concentration of THDOC and the DHEAS/cortisol ratio were lower (p < 0.05) in women with CE than in control women. The concentrations of P4, pregnenolone, and AP did not differ between the two groups of subjects.

CONCLUSIONS

The reduced serum concentration of THDOC and the reduced DHEAS/cortisol ratio detected throughout the menstrual cycle in women with CE might play a role in CE. Moreover, the peculiar pattern of CE seizure exacerbation might suggest that these neuroendocrine variations are worth investigating in other epileptic syndromes, particularly in those characterized by relevant and uncontrolled variations in seizure frequency.

BACKGROUND

Differential pathogenicity has been observed in cynomolgus and rhesus macaques following primate lentivirus infection. However, little is known about the comparative susceptibility of pig-tailed macaques to lentivirus infection and diseases.

METHODS

We compared the in vivo infectivity and pathogenicity of a CCR5-tropic SHIV(SF162 P4) after intravenous, intravaginal or intrarectal inoculation in rhesus and pig-tailed macaques. Plasma viral load, peripheral blood CD4(+) T cell counts and clinical signs were monitored.

RESULTS

Both rhesus and pig-tailed macaques are similarly susceptible to SHIV(SF162 P4) infection by intravenous and mucosal routes. However, infection was significantly more robust in pig-tailed macaques than in rhesus, resulting in persistent viremia in 9/21 pig-tails vs. 2/24 rhesus (P < 0.013) and severe CD4(+) T-cell depletion in 2/21 pig-tails (vs. none in rhesus).

CONCLUSIONS

Together with earlier observations, our findings underscore the importance of considering host genetic and immunological factors when comparing vaccine efficacy in different macaque species.

In vitro ovary culture in rats was used to characterize ovarian steroidogenesis and to evaluate changes produced by in vivo exposure to bis(2-diethylhexyl)phthalate (DEHP). Steroid profiles [progesterone (P4), estradiol (E2), and testosterone (T)] from cultures of minced ovary were obtained in untreated immature and mature rats, and from mature rats treated with DEHP. A 1-h incubation without human chorionic gonadotropin (hCG) was used to produce an initial steroidogenic profile. Three 1-h incubations with hCG were used to produce a stimulated steroid profile. A combination of initial and stimulated ovarian steroid profiles was shown to correctly identify the stage of the cycle in all untreated rats, using multivariate statistical analysis. Separately, initial or stimulated ovarian steroid profiles correctly identified the stage of the cycle in more than 90% of the rats. The statistical analysis using a combination of variables (multivariate) indicated that DEHP-treated rats were significantly different (P < 0.001) from sham-treated rats. In fact, the alteration caused by DEHP in the in vitro ovarian steroidogenic profile was most apparent in rats during diestrus and estrus. In DEHP-treated rats in diestrus, ovarian steroidogenesis appeared to shift to the production of more T and more E2 than in untreated rats in diestrus. The change seen in steroid profiles in DEHP-treated rats in estrus is to decreased E2 production. The steroid profile from ovary culture in conjunction with vaginal cytology was very useful in correctly identifying in vivo DEHP-treated rats, and will be a useful in vitro technique in the evaluation of ovarian toxicants in cycling females.

Studies of callosal projections in striate cortex show that the retina is involved in the development of topographical connections. In normal animals callosal fibers connect retinotopically corresponding, nonmirror-symmetric cortical loci, whereas in animals bilaterally enucleated at birth, callosal fibers connect topographically mismatched, mirror-symmetric loci. Moreover, in rodents the overall pattern of visual callosal connections is adult-like by postnatal day 12 (P12). In this study we delayed the onset of retinal deafferentation in rats and mice in order to determine the period when retinal influences are critically needed for the development of retinotopically matched callosal linkages. Callosal maps were revealed by placing small injections of retrogradely and anterogradely transported tracers into different loci of lateral striate cortex. We found that the patterns of callosal linkages in rats enucleated at P12, P8, and P6 were nonmirror-symmetric, as in normally reared rats. In contrast, the patterns of linkages in rats enucleated at P4 closely resembled the mirror-symmetric pattern seen in rats enucleated at birth (P0). A similar reversal in topography (from symmetric to nonsymmetric) occurred in mice when enucleation was delayed from P4 to P6. These findings indicate that retinal input prior to P6, but not prior to P4, is sufficient for specifying normal callosal topography. Moreover, they suggest that development of retinotopically matched callosal linkages depends critically on retinal influences during a brief period between P4 and P6, when callosal connections are still very immature.

Pseudomonas exotoxin (PE) requires proteolytic cleavage to generate a 37-kDa C-terminal fragment that translocates to the cytosol and ADP-ribosylates elongation factor 2. Cleavage within cells is mediated by furin, occurs between arginine 279 and glycine 280, and requires an arginine at both P1 and P4 residues. To study the proteolytic processing of PE-derived chimeric toxins, TGFalpha-PE38 (transforming growth factor fused to the domains II and III of PE) and a mutant form, TGFalpha-PE38gly279, were each produced in Escherichia coli. When assessed on various epidermal growth factor (EGF) receptor-positive cell lines, TGFalpha-PE38 was 100-500-fold more toxic than TGFalpha-PE38gly279. In contrast to PE, where cleavage by furin is only evident at pH 5.5, furin cleaved TGFalpha-PE38 over a broad pH range, while TGFalpha-PE38gly279 was resistant to cleavage. TGFalpha-PE38 was poorly toxic for furin-deficient LoVo cells, unless it was first pretreated in vitro with furin. Furin treatment produced a nicked protein that was 30-fold more toxic than its unnicked counterpart. Using the single chain immunotoxin HB21scFv-PE40 as a substrate, furin-mediated processing of an antibody-based immunotoxin was also evaluated. HB21scFv-PE40, which targets cells expressing the transferrin receptor, was cleaved in a similar fashion to that of TGFalpha-PE38 and nicked HB21scFv-PE40 exhibited increased toxicity for LoVo cells. In short-term experiments, the rate of reduction in protein synthesis by furin-nicked immunotoxins was increased compared with unnicked protein, indicating that cleavage by furin can be a rate-limiting step. We conclude that furin-mediated cleavage of PE-derived immunotoxins is important for their cytotoxic activity.

Progesterone (P4) is cytoprotective in various experimental models, but our understanding of the mechanisms involved is still incomplete. Our laboratory has implicated brain-derived neurotrophic factor (BDNF) signaling as an important mediator of P4's protective actions. We have shown that P4 increases the expression of BDNF, an effect mediated by the classical P4 receptor (PR), and that the protective effects of P4 were abolished using inhibitors of Trk receptor signaling. In an effort to extend our understanding of the interrelationship between P4 and BDNF signaling, we determined whether P4 influenced BDNF release and examined the role of the classical PR and a putative membrane PR, progesterone receptor membrane component-1 (Pgrmc1), as mediators of this response. Given recent data from our laboratory that supported the role of ERK5 in BDNF release, we also tested whether P4-induced BDNF release was mediated by ERK5. In this study, we found that P4 and the membrane-impermeable P4 (P4-BSA) both induced BDNF release from cultured C6 glial cells and primary astrocytes. Both these cells lack the classical nuclear/intracellular PR but express high levels of membrane-associated PR, including Pgrmc1. Using RNA interference-mediated knockdown of Pgrmc1 expression, we determined that P4-induced BDNF release was dependent on the expression of Pgrmc1, although pharmacological inhibition of the PR failed to alter the effects of P4. Furthermore, the BDNF release elicited by P4 was mediated by ERK5, and not ERK1/2. Collectively, our data describe that P4 elicits an increase in BDNF release from glia via a Pgrmc1-induced ERK5 signaling mechanism and identify Pgrmc1 as a potential therapeutic target for future hormone-based drug development for the treatment of such degenerative diseases as Alzheimer's disease as well as other diseases wherein neurotrophin dysregulation is noted.

Glioblastoma multiforme (GBM) is an aggressive primary brain tumor with a mean patient survival of 13-15 months despite surgical resection, radiation therapy and standard-of-care chemotherapy. We investigated the chemotherapeutic effects of the hormone progesterone (P4) on the growth of human GBM in four genetically different cell lines (U87MG, U87dEGFR, U118MG, LN-229) in vitro and in a U87MG subcutaneous xenograft mouse model. At high concentrations (20, 40, and 80 μM), P4 significantly (P<0.05) decreased tumor cell viability in all cell lines except LN-229. This effect was not blocked by the P4 receptor antagonist RU468. Conversely, at low physiological concentrations (0.1, 1, and 5 μM) P4 showed a proliferative effect in all cell lines which was blocked by RU486. In nude mice, P4 (100 and 200 mg/kg) inhibited tumor growth significantly (P<0.05) over 5 weeks of treatment and extended survival time of tumor-bearing mice by 60% without signs of systemic toxicity. P4 suppressed tumor vascularization as indicated by the expression of CD31, vascular endothelial growth factor and matrix metalloproteinase-9. Apoptosis in tumor tissue was detected by the expression of cleaved caspase-3, BCl-2, BAD and p53 proteins and confirmed by TUNEL assay. P4 treatment also suppressed PI3K/Akt/mTOR signaling, which regulates tumor growth, as demonstrated by the suppression of proliferating cell nuclear antigen. Our data can be interpreted to suggest that P4 suppresses the growth of human GBM cells both in vitro and in vivo and enhances survival time in mice without any demonstrable side effects. This article is part of a Special Issue entitled 'Sex steroids and brain disorders'.

Uterine gland development (adenogenesis) in mice begins on Postnatal Day (PND) 5 and is completed in adulthood. Adenogenesis depends on estrogen receptor 1, and progesterone (P4) inhibits mitogenic effects of estrogen on uterine epithelium. This progestin-induced effect has been used to inhibit uterine gland development; progestin treatment of ewes for 8 wk from birth has produced infertile adults lacking uterine glands. The goals of the present study were to determine if a window of susceptibility to P4-mediated inhibition of uterine gland development exists in mice and whether early P4 treatment abolishes adenogenesis and fertility. Mice were injected daily with P4 (40 μg/g) or vehicle during various postnatal windows. Adenogenesis, cell proliferation, and expression of key morphoregulatory transcripts and proteins were examined in uteri at PNDs 10 and 20. Additionally, adenogenesis was assessed in isolated uterine epithelium. Treatment during PNDs 3-9, 5-9, or 3-7 abolished adenogenesis at PND 10, whereas treatments during PNDs 3-5 and 7-9 did not. Critically, mice treated during PNDs 3-9 lacked glands in adulthood, indicating that adenogenesis did not resume after this treatment. However, glands were present by PND 20 and later following treatment during PNDs 5-9 or 3-7, whereas treatment during PNDs 10-16 produced partial inhibition of adenogenesis at PND 20 and later. Epithelial proliferation at PND 10 was low following P4 treatment (PNDs 3-9) but exceeded that in controls at PND 20, indicating a rebound of epithelial proliferation following treatment. Messenger RNA for Wnt, Fzd, and Hox genes was altered by neonatal P4 treatment. All groups cycled during adulthood. Mice treated with P4 during PNDs 3-9, but not during other developmental windows, showed minimal fertility in adulthood. In summary, brief P4 treatment (7 days) during a critical neonatal window (PNDs 3-9) transiently inhibited epithelial proliferation but totally and permanently blocked adenogenesis and adult fertility. This resulted in permanent loss of uterine glands and, essentially, total infertility during adulthood. The narrow window for inhibition of adenogenesis identified here may have implications for development of this methodology as a contraceptive strategy for animals.

Tryptophan 2,3-dioxygenase (TDO), an initial and rate-limiting enzyme for the kynurenine pathway of tryptophan (Trp) metabolism, is thought to play an important role in systemic Trp metabolism as well as in emotional and psychiatric status. In contrast to its predominant expression in the liver, expression of TDO in the brain is poorly understood. Here, we show that tdo mRNA is expressed in various nervous tissues, including the hippocampus, cerebellum, striatum and brainstem. During development, tdo mRNA was differentially regulated in brain tissues. Further, we identified two novel variants of the tdo gene, termed tdo variant1 and variant2. Similar tetramer formation and enzymatic activity were obtained when these forms were expressed in wheat germ and COS-7 cells, respectively. Quantitative real-time RT-PCR revealed that tdo variants were expressed in various nervous tissues, with high expression in the cerebellum and hippocampus, followed by the midbrain. tdo variant2 was the only variant expressed in the cerebellum from postnatal day 4 (P4) to P7, suggesting a unique role for this variant during early postnatal development. Our findings indicate that tdo and its novel variants may play an important role in not only the liver but also in local areas in developing and adult brain.

Circular RNA (circRNA) play important roles in the pathological processes of many diseases. By analyzing the results of the GSE100186 chip, we found that the expression of circRNA ZNF609 (circ-ZNF609) was significantly increased in renal cell carcinoma. Recently, there are studies showing that circ-ZNF609 can regulate cell proliferation and invasion ability of various cells. In this study, we investigated whether circ-ZNF609 may affect cell invasion and proliferation in renal carcinoma. Quantitative reverse transcription polymerase chain reaction was performed to detect the expression of circ-ZNF609 in renal carcinoma cell lines and renal epithelial cells. The direct interaction between microRNA-138-5p (miR-138-5p) and forkhead box P4 (FOXP4) or circ-ZNF609 was confirmed by luciferase reporter assay and RNA immunoprecipitation assay. We use Cell Counting Kit-8, 5-ethynyl-2'-deoxyuridine, and Matrigel assays to assess the effect of miR-138-5p or circ-ZNF609 on cell proliferation or invasion ability. And we found that circ-ZNF609 is significantly increased in renal carcinoma cell lines. In addition, the high expression of circ-ZNF609 promotes cell proliferation and invasion ability. In short, our current study reveals the role of the circ-ZNF609/miR-138-5p/FOXP4 regulatory network in renal carcinoma and provides a new perspective for the pathogenesis of renal carcinoma.

Stroking the mucosal lining of the guinea pig colon with a brush elicits an intestinal neural reflex, and an increase in short-circuit current (Isc) indicative of chloride secretion. We tested whether endogenous and exogenous nucleotides are physiologic regulators of mucosal reflexes that modulate chloride secretion. The basal Isc was augmented by 6-N,N-diethyl-beta,gamma-dibromomethylene-D-adenosine-5'-triphosphate (ARL67156) inhibition of nucleotide breakdown or adenosine A1 receptor blockade and reduced by apyrase inactivation of nucleotidases, P2 receptor antagonists, tetrodotoxin (TTX), or piroxicam. ARL67156 augmented, and apyrase inhibited, stroking-evoked Isc responses. TTX and atropine inhibited nucleotide-evoked Isc responses. The agonist potency profile for Isc, 2-methylthioadenosine-diphosphate (2MeSADP) = 2-methioadenosine-triphosphate>>) 5'adenosine-triphosphate (ATP)>> or = 5'adenosine-diphosphate>> 5'uridine-triphosphate>> or = 5'uridine-diphosphate, supports a P2Y1 receptor (R). The P2 receptor antagonists suramin and pyridoxalphosphate-6-azophenyl-2'4'-disulfonic acid, reduced stroking responses (36%) and their effects were additive. The selective P2Y1 R antagonist, 2'deoxy-N6-methyl adenosine 3',5'-diphosphate diammonium salt, reduced stroking (54%) and 2MeSADP (70%) responses at P2Y1 Rs. The P2X1/3 R agonist, alpha,betaMeATP, increased Isc. A desensitizing dose of alpha,betaMeATP reduced stroking Isc responses but did not prevent the 2MeSADP-evoked Isc response. Reverse transcriptase polymerase chain reaction analysis revealed mRNAs for P2Y1 R, P2Y2 R, P2Y4 R, P2Y6 R, and P2Y12 R in submucosa. The expression of P2Y R immunoreactivity (ir) in cell bodies of submucous neurons followed the order of P2Y1 = P2Y2>>) P2Y4 R ir; P2Y1 Rs and P2Y2 R ir were abundant (21-50% of neurons). P2Y1 R ir was abundant in cholinergic secretomotor neurons and fewer than 2% of neuropeptide Y (NPY)/choline acetyltransferase secretomotor neurons, and P2Y2 R ir was expressed in virtually all NPY secretomotor neurons and approximately 30% of calbindin/intrinsic primary afferent neurons. P2Y4 R ir was present in NPY-positive neurons. P2Y ir was rare or absent in varicose nerve fibers. The functional data support the hypothesis that mechanical stimulation with a brush releases nucleotides that act predominantly at P2Y1 Rs and to a lesser extent on P2X1/3 Rs to mediate reflex chloride secretion. A separate P2Y2 R neural circuit pathway exists that is not activated by mechanical forces. Other receptors including P2Y4, P2Y6, P2Y12, or P4 Rs cannot be excluded.

Bacteriophages T7, λ, P22, and P2/P4 (from Escherichia coli), as well as ϕ29 (from Bacillus subtilis), are among the best-studied bacterial viruses. This chapter summarizes published protein interaction data of intraviral protein interactions, as well as known phage-host protein interactions of these phages retrieved from the literature. We also review the published results of comprehensive protein interaction analyses of Pneumococcus phages Dp-1 and Cp-1, as well as coliphages λ and T7. For example, the ≈55 proteins encoded by the T7 genome are connected by ≈43 interactions with another ≈15 between the phage and its host. The chapter compiles published interactions for the well-studied phages λ (33 intra-phage/22 phage-host), P22 (38/9), P2/P4 (14/3), and ϕ29 (20/2). We discuss whether different interaction patterns reflect different phage lifestyles or whether they may be artifacts of sampling. Phages that infect the same host can interact with different host target proteins, as exemplified by E. coli phage λ and T7. Despite decades of intensive investigation, only a fraction of these phage interactomes are known. Technical limitations and a lack of depth in many studies explain the gaps in our knowledge. Strategies to complete current interactome maps are described. Although limited space precludes detailed overviews of phage molecular biology, this compilation will allow future studies to put interaction data into the context of phage biology.

OBJECTIVE

To assess the survival of rod precursor cells transplanted into the Rd9 mouse, a model of X-linked retinal degeneration, and the effect of antiapoptotic therapy with X-linked inhibitor of apoptosis (XIAP) on preventing cell loss.

METHODS

Dissociated retinal cells from P4 Nrlp-GFP mice were transplanted into the subretinal space of 2-, 5-, and 8-month-old Rd9 mice. Histology, immunohistochemistry, and quantification of integrated cells were performed every month for up to 3 months after transplantation. XIAP delivery to donor cells was accomplished by transfection with adenoassociated virus (AAV-XIAP). Intraretinal activation of immune modulators was assessed using a quantitative real-time polymerase chain reaction-based immune response array.

RESULTS

GFP-positive rod precursors were able to integrate into the outer nuclear layer (ONL) of the Rd9 retina. Transplanted cells underwent morphologic differentiation with the formation of inner and outer segments and synaptic projections to bipolar cells. Integration of donor cells into the ONL increased as a function of host age at the time of transplantation. The number of integrated cells was maximal at 1 month after transplantation and then decreased with time. Survival of integrated cells was significantly increased when donor cells were pretreated with AAV-XIAP. We did not detect any donor cell-specific activation of inflammation within the host retina.

CONCLUSIONS

Survival of integrated cells decreases with time after transplantation but can be significantly increased with XIAP antiapoptotic therapy. Preventing programmed cell death through XIAP therapy may be an important component of future therapeutic retinal cell transplantation strategies.

GnRH neurons are essential for reproduction, being an integral component of the hypothalamic-pituitary-gonadal axis. Progesterone (P4), a steroid hormone, modulates reproductive behavior and is associated with rapid changes in GnRH secretion. However, a direct action of P4 on GnRH neurons has not been previously described. Receptors in the progestin/adipoQ receptor family (PAQR), as well as progesterone receptor membrane component 1 (PgRMC1) and its partner serpin peptidase inhibitor, clade E (nexin, plasminogen activator inhibitor type 1) mRNA binding protein 1 (SERBP1), have been shown to mediate rapid progestin actions in various tissues, including the brain. This study shows that PgRMC1 and SERBP1, but not PAQR, are expressed in prenatal GnRH neurons. Expression of PgRMC1 and SERBP1 was verified in adult mouse GnRH neurons. To investigate the effect of P4 on GnRH neuronal activity, calcium imaging was used on primary GnRH neurons maintained in explants. Application of P4 significantly decreased the activity of GnRH neurons, independent of secretion of gamma-aminobutyric acidergic and glutamatergic input, suggesting a direct action of P4 on GnRH neurons. Inhibition was not blocked by RU486, an antagonist of the classic nuclear P4 receptor. Inhibition was also maintained after uncoupling of the inhibitory regulative G protein (G(i/o)), the signal transduction pathway used by PAQR. However, AG-205, a PgRMC1 ligand and inhibitor, blocked the rapid P4-mediated inhibition, and inhibition of protein kinase G, thought to be activated downstream of PgRMC1, also blocked the inhibitory activity of P4. These data show for the first time that P4 can act directly on GnRH neurons through PgRMC1 to inhibit neuronal activity.

The proprotein convertases (PCs) participate in the limited proteolysis of integrin alpha4 subunit at the H(592)VISKR(597) downward arrow ST site (where underlined residues indicate positively charged amino acids important for PC-mediated cleavage and downward arrow indicates the cleavage site), since this cleavage is inhibited by the serpin alpha1-PDX (alpha1-antitrypsin Portland). Co-expression of alpha4 with each convertase in LoVo (furin-deficient human colon carcinoma) cells revealed that furin and proprotein convertase 5A (PC5A) are the best pro-alpha4 convertases. In agreement, processing of endogenous pro-alpha4 in human lymphoblastoid CEM-T4 cells was enhanced greatly in stable transfectants overexpressing either enzyme. In many leucocyte cell lines, the expression of furin closely correlated with the endogenous processing efficacy, suggesting that furin is a candidate pro-alpha4 convertase. Mutational analysis showed that replacement of P1 Arg(597) with alanine (R597A) abrogated cleavage, whereas the P6 mutant H592R is even better processed by the endogenous convertases of Chinese-hamster ovary CHO-K1 cells. In vitro kinetic studies using synthetic peptides confirmed the importance of a positively charged residue at P6 and showed that wild-type alpha4 processing is performed best by furin and PC5A at acidic and neutral pHs, respectively. Biosynthetic analysis of pro-alpha4 and its H592R and H592K mutants in the presence or absence of the weak base, NH(4)Cl, revealed that the P6 histidine residue renders its processing by furin sensitive to cellular pH. This suggests that pro-alpha4 cleavage occurs preferentially in acidic compartments. In conclusion, although the accepted furin processing motif is Arg-Xaa-(Lys/Arg)-Arg downward arrow, our data further extend it to include a regulatory histidine residue at P6 in precursors that lack a basic residue at P4.

HLA-DQ8 (A1*0301, B1*0302) and -DQ2 (A1*0501, B1*0201) are both associated with diseases such as insulin-dependent diabetes mellitus and coeliac disease. We used the technique of pool sequencing to look at the requirements of peptides binding to HLA-DQ8, and combined these data with naturally sequenced ligands and in vitro binding assays to describe a novel motif for HLA-DQ8. The motif, which has the same basic format as many HLA-DR molecules, consists of four or five anchor regions, in the positions from the N-terminus of the binding core of n, n + 3, n + 5/6 and n + 8, i.e. P1, P4, P6/7 and P9. P1 and P9 require negative or polar residues, with mainly aliphatic residues at P4 and P6/7. The features of the HLA-DQ8 motif were then compared to a pool sequence of peptides eluted from HLA-DQ2. A consensus motif for the binding of a common peptide which may be involved in disease pathogenesis is described. Neither of the disease-associated alleles HLA-DQ2 and -DQ8 have Asp at position 57 of the beta-chain. This Asp, if present, may form a salt bridge with an Arg at position 79 of the alpha-chain and so alter the binding specificity of P9. HLA-DQ2 and -DQ8 both appear to prefer negatively charged amino acids at P9. In contrast, HLA-DQ7 (A1*0301, B1*0301), which is not associated with diabetes, has Asp at beta 57, allowing positively charged amino acids at P9. This analysis of the sequence features of DQ-binding peptides suggests molecular characteristics which may be useful to predict epitopes involved in disease pathogenesis.

The pioneering work of Jean Dausset on the HLA system established several principles that were later reflected in the Human Genome Project and contributed to the foundations of predictive, preventive, personalized and participatory (P4) medicine. To effectively develop systems medicine, we should take advantage of the lessons of the HLA saga, emphasizing the importance of exploring a fascinating but mysterious biology, now using systems principles, pioneering new technology developments and creating shared biological and information resources.

This study investigated the effects of progesterone (P4) on the production and survival of neurons in the hippocampal dentate gyrus of adult male mice. The administration of P4 (4 mg/kg) for 3 consecutive days beginning on the 0-2nd day after the first BrdU-injection (BrdU-D(0-2)) produced an approximately twofold increase in the number of 28- and 56-day-old BrdU(+) cells in comparison to the controls, whereas it did not alter the number of 24/48-h-old BrdU(+) cells. P4 preferentially promoted the survival of newborn neurons when administered at BrdU-D(5-7), but not at BrdU-D(10-12) and BrdU-D(15-17). Androstenedione (Ad), testosterone (TE), or estradiol (E2) at the same-dose of P4, when administered at BrdU-D(0-2), could not replicate the effect of P4, while the inhibition of 5alpha-reductase by finasteride did not affect the P4-action, indicating that the P4-effect is exerted by P4 itself but not by its metabolites. On the other hand, the P4R antagonist RU486 partially suppressed the P4-effect, while inhibitors for Src, MEK, or PI3K totally suppressed the P4-effect. Finally, the P4-enhanced survival of newborn neurons was accompanied by a potentiation of spatial learning and memory, which was P4R-dependent. These findings suggest that P4 enhances the survival of newborn neurons through P4R and/or the Src-ERK and PI3K pathways independent of its influence on cell proliferation, which is well correlated with the potentiated spatial cognitive function of P4-treated animals.

Degradation of fibrillar collagens is important in many physiological and pathological events. These collagens are resistant to most proteases due to the tightly packed triple-helical structure, but are readily cleaved at a specific site by collagenases, selected members of the matrix metalloproteinases (MMPs). To investigate the structural requirements for collagenolysis, varying numbers of GXY triplets from human type III collagen around the collagenase cleavage site were inserted between two triple helix domains of the Scl2 bacterial collagen protein. The original bacterial CL domain was not cleaved by MMP-1 (collagenase 1) or MMP-13 (collagenase 3). The minimum type III sequence necessary for cleavage by the two collagenases was 5 GXY triplets, including 4 residues before and 11 residues after the cleavage site (P4-P11'). Cleavage of these chimeric substrates was not achieved by the catalytic domain of MMP-1 or MMP-13, nor by full-length MMP-3. Kinetic analysis of the chimeras indicated that the rate of cleavage by MMP-1 of the chimera containing six triplets (P7-P11') of collagen III was similar to that of native collagen III. The collagenase-susceptible chimeras were cleaved very slowly by trypsin, a property also seen for native collagen III, supporting a local structural relaxation of the triple helix near the collagenase cleavage site. The recombinant bacterial-human collagen system characterized here is a good model to investigate the specificity and mechanism of action of collagenases.