A highly conserved 3-methylhistidine modification is absent in yeast actin

To identify a protein histidine methyltransferase from Saccharomyces cerevisiae, we examined purified actin for the presence of the highly conserved 3-methylhistidine residue at position 73 by amino acid analysis of the whole protein and by amino acid analysis and mass spectrometry of the corresponding tryptic fragment. Surprisingly, we found that His-73 is not modified. A similar lack of modification was also found in actin from the yeast Candida albicans, while rabbit muscle actin revealed the expected 3-methylhistidine residue. Phylogenetic analysis of actin sequences suggests that this modification was introduced in evolution after the divergence of yeast from higher eukaryotic organisms, including unicellular eukaryotes such as Acanthamoeba, Dictyostelium, and Physarum, whose actins contain 3-methylhistidine. Our methodology for the analytical determination of 3-methylhistidine in actin offers an improved approach for investigating histidine methylation in proteins.

French Machado-Joseph disease patients do not exhibit gametic segregation distortion: a sperm typing analysis

Segregation distortion has been reported to occur in a number of the trinucleotide repeat disorders. On the basis of a sperm typing study performed in patients of Japanese descent with Machado-Joseph disease (MJD), it was reported that disease alleles are preferentially transmitted during meiosis. We performed a sperm typing study of five MJD patients of French descent and analysis of the pooled data shows a ratio of mutant to normal alleles of 379:436 (46.5:53.5%), which does not support meiotic segregation distortion. To confirm these results, sperm typing analysis was also performed using a polymorphic marker, D14S1050, closely linked to the MJD1 gene. Among 910 sperm analyzed, the allele linked to the disease chromosome was detected in 50.3% of the samples and the allele linked to the normal chromosome was found in 49.6% of the sperm. The difference in frequency of these two alleles is not significant ( P = 0.8423). Likelihood-based analysis of segregation distortion in the single sperm data using the SPERMSEG program also showed no support for segregation distortion at the gamete level in this patient population. The previous report on the Japanese patients also suggested that disease allele stability may be influenced by a trans effect of an intragenic polymorphism (987 G/C) in the wild-type allele. All of the French patients were heterozygous for this polymorphism. However, analysis of the variance in repeat number in sperm from the French MJD patients overlapped significantly with the variance in repeat number observed in the C/C homozygous Japanese patients.

[Expression of heat shock protein (HSP70) in normal endometrium and endometrial carcinomas]

Expression of heat shock protein 70 (HSP70) in normal endometrium tissue and endometrial carcinoma was analyzed by the present authors to determine the relationship between HSP70 expression and the prognosis of endometrial carcinomas. The immunohistochemical reactivity of monoclonal antibodies against HSP70 was examined in 44 endometrial carcinomas and 40 normal endometria HSP70 respectively. HSP70 was expressed stronger in carcinomas than in normal. Expression of HSP70 was found in 56.82% of endometrial carcinomas and was well correlated with histological grade (P < 0.05). These results suggest that HSP70 may play a role in the prognosis of endometrial carcinomas.

Activity of voltage-gated K+ channels is associated with cell proliferation and Ca2+ influx in carcinoma cells of colon cancer

Cell proliferation of carcinoma cells DLD-1 derived from colon cancer as measured by [3H] thymidine incorporation was drastically reduced in the presence of 4-aminopyridine, an inhibitors of voltage-gated K channel. A number of nonspecific K+ channel inhibitors including TPeA, TEA, verapamil and diltiazem also inhibited [3H] incorporation at the concentration reported to inhibit voltage-gated K+ channels. The presence of voltage-gated K+ channels was confirmed by reverse transcription-PCR and cDNA sequencing. Charybdotoxin and iberiotoxin, inhibitors for Ca2+-sensitive K+ channel, and glibenclamide, a specific inhibitor for ATP-sensitive K+ channel, did not have effect on cell proliferation. These experiments suggested a critical role of voltage-gated K+ channels in proliferation of colon cancer cells. Mechanism of action of K+ channel activity in cell proliferation was explored by studying the relationship between the K+ channel activity and Ca2+ entry. The results from experiments indicated that K+ channel inhibitors blocked [Ca2+]i influx. Therefore, it is likely that K+ channel activity may modulate Ca2+ influx into colon cancer cells, and subsequently modulate the proliferation of these cells.

Inherited human Caspase 10 mutations underlie defective lymphocyte and dendritic cell apoptosis in autoimmune lymphoproliferative syndrome type II

Caspases are cysteine proteases that mediate programmed cell death in phylogenetically diverse multicellular organisms. We report here two kindreds with autoimmune lymphoproliferative syndrome (ALPS) type II, characterized by abnormal lymphocyte and dendritic cell homeostasis and immune regulatory defects, that harbor independent missense mutations in Caspase 10. These encode amino acid substitutions that decrease caspase activity and interfere with death receptor-induced apoptosis, particularly that stimulated by Fas ligand and TRAIL. These results provide evidence that inherited nonlethal caspase abnormalities cause pleiotropic apoptosis defects underlying autoimmunity in ALPS type II.

[Study on HBV preS/S gene mutation in peripheral blood mononuclear cells]

OBJECTIVE

To study the significance of mutations of HBV preS and S genes in peripheral blood mononuclear cells (PBMC).

METHODS

Srea and PBMCs of 19 chronic hepatitis B patients were collected. The S, preS1 and preS2 gene fragments of HBV were separately amplified by PCR, and 5 cases of preS1 and preS2 gene fragments in paired sera and PBMC were sequenced.

RESULTS

The positive rates of S, preS1 and preS2 gene fragments in serum and PBMC were 100%, 94.7%, 100% and 0, 26.3%, 26.3% respectively. Sequence analysis of preS1 and preS2 genes showed that in 8/10 specimens there were point mutations in preS1 and 7/10 mutations in preS2; while in the others (2 of preS1 and 3 of preS2) the sequences were identical to that of wild-type HBV.

CONCLUSION

No full-length HBV genome in PBMC was detected by PCR, this is a fact not supporting that HBV can replicate, assemble and release from PBMC. The amino acid changes predicted mutatieds from nucleotide were focused in aa21-47 region, which might affect adsorption and penetration of HBV, and alteration in tissue tropism. Whether the presence of HBV subgenomic fragments in PBMC can affect cell function should be pursued.

Different mutator phenotypes in Mlh1- versus Pms2-deficient mice

Deficiencies in DNA mismatch repair (MMR) result in increased mutation rates and cancer risk in both humans and mice. Mouse strains homozygous for knockouts of either the Pms2 or Mlh1 MMR gene develop cancer but exhibit very different tumor spectra; only Mlh1(-/-) animals develop intestinal tumors. We carried out a detailed study of the microsatellite mutation spectra in each knockout strain. Five mononucleotide repeat tracts at four different chromosomal locations were studied by using single-molecule PCR or an in vivo forward mutation assay. Three dinucleotide repeat loci also were examined. Surprisingly, the mononucleotide repeat mutation frequency in Mlh1(-/-) mice was 2- to 3-fold higher than in Pms2(-/-) animals. The higher mutation frequency in Mlh1(-/-) mice may be a consequence of some residual DNA repair capacity in the Pms2(-/-) animals. Relevant to this idea, we observed that Pms2(-/-) mice exhibit almost normal levels of Mlh1p, whereas Mlh1(-/-) animals lack both Mlh1p and Pms2p. Comparison between Mlh1(-/-) animals and Mlh1(-/-) and Pms2(-/-) double knockout mice revealed little difference in mutator phenotype, suggesting that Mlh1 nullizygosity is sufficient to inactivate MMR completely. The findings may provide a basis for understanding the greater predisposition to intestinal cancer of Mlh1(-/-) mice. Small differences (2- to 3-fold) in mononucleotide repeat mutation rates may have dramatic effects on tumor development, requiring multiple genetic alterations in coding regions. Alternatively, this strain difference in tumor spectra also may be related to the consequences of the absence of Pms2p compared with the absence of both Pms2p and Mlh1p on as yet little understood cellular processes.

Solution structure of the chicken cysteine-rich protein, CRP1, a double-LIM protein implicated in muscle differentiation

The mechanism by which the contractile machinery of muscle is assembled and maintained is not well-understood. Members of the cysteine-rich protein (CRP) family have been implicated in these processes. Three vertebrate CRPs (CRP1-3) that exhibit developmentally regulated muscle-specific expression have been identified. All three proteins are associated with the actin cytoskeleton, and one has been shown to be required for striated muscle structure and function. The vertebrate CRPs identified to date display a similar molecular architecture; each protein is comprised of two tandemly arrayed LIM domains, protein-binding motifs found in a number of proteins with roles in cell differentiation. Each LIM domain coordinates two Zn(II) ions that are bound independently in CCHC (C=Cys, H=His) and CCCC modules. Here we describe the solution structure of chicken CRP1 determined by homonuclear and 1H-15N heteronuclear magnetic resonance spectroscopy. Comparison of the structures of the two LIM domains of CRP1 reveals a high degree of similarity in their tertiary folds. In addition, the two component LIM domains represent two completely independent folding units and exhibit no apparent interactions with each other. The structural independence and spatial separation of the two LIM domains of CRP1 are compatible with an adapter or linker role for the protein.

Cell-based and animal models for hepatitis B and C viruses

Reliable cell-based assays and animal models have been developed for evaluating agents against hepatitis B virus. Although much progress has been made, in vitro and in vivo assays for hepatitis C virus are still on the horizon. Advances towards establishing inexpensive and reliable experimental models have accelerated the development of therapeutic modalities for these life-threatening viral infections. The characterization of well-defined viral targets coupled with improved molecular diagnostic technologies have illuminated this field.

Comparison of the backbone dynamics of the apo- and holo-carboxy-terminal domain of the biotin carboxyl carrier subunit of Escherichia coli acetyl-CoA carboxylase

The biotin carboxyl carrier protein (BCCP) is a subunit of acetyl-CoA carboxylase, a biotin-dependent enzyme that catalyzes the first committed step of fatty acid biosynthesis. In its functional cycle, this protein engages in heterologous protein-protein interactions with three distinct partners, depending on its state of post-translational modification. Apo-BCCP interacts specifically with the biotin holoenzyme synthetase, BirA, which results in the post-translational attachment of biotin to a single lysine residue on BCCP. Holo-BCCP then interacts with the biotin carboxylase subunit of acetyl-CoA carboxylase, which leads to the addition of the carboxylate group of bicarbonate to biotin. Finally, the carboxy-biotinylated form of BCCP interacts with transcarboxylase in the transfer of the carboxylate to acetyl-CoA to form malonyl-CoA. The determinants of protein-protein interaction specificity in this system are unknown. The NMR solution structure of the unbiotinylated form of an 87 residue C-terminal domain fragment (residue 70-156) of BCCP (holoBCCP87) and the crystal structure of the biotinylated form of a C-terminal fragment (residue 77-156) of BCCP from Escherichia coli acetyl-CoA carboxylase have previously been determined. Comparative analysis of these structures provided evidence for small, localized conformational changes in the biotin-binding region upon biotinylation of the protein. These structural changes may be important for regulating specific protein-protein interactions. Since the dynamic properties of proteins are correlated with local structural environments, we have determined the relaxation parameters of the backbone 15N nuclear spins of holoBCCP87, and compared these with the data obtained for the apo protein. The results indicate that upon biotinylation, the inherent mobility of the biotin-binding region and the protruding thumb, with which the biotin group interacts in the holo protein, are significantly reduced.

Antineoplastic agents. III: Steroidal glycosides from Solanum nigrum

By bioactivity-guided fractionation, three known steroidal glycosides, beta 2-solamargine (1), solamargine (2), and degalactotigonin (3), were isolated from Solanum nigrum. Compounds 1-3 induced morphological abnormality in Pyricularia oryzae mycelia with MMDC (minimum morphological deformation concentration) values of 63.0, 38.5, and 97.2 microM, respectively. This is the first report on the isolation of 1 from this species and on the cytotoxicity of 1-3 on six cultured human solid tumor cell lines HT-29 (colon), HCT-15 (colon), LNCaP (prostate), PC-3 (prostate), T47D (breast), and MDA-MB-231 (breast) in vitro. The cytotoxic assay indicated that 2 is the main antineoplastic agent in S. nigrum. The structures of 1-3 were elucidated on the basis of chemical evidence and spectral analysis, especially by 2D-NMR analysis.

[Spontaneous renal rupture]

OBJECTIVE

To study clinical regularity of spontaneous renal rupture.

METHODS

16 cases of this disease were reviewed. Renal carcinoma was found in 4, angiomyolipoma in 2, undetermined etiology in 3, and invasive colic cancer, kidney cyst, nephrolithiasis, SLE with nephritis, polycythemia vera, renal tuberculosis, portal hypertension in 1 each.

RESULTS

CT demonstrated a sensitivity of 87.5% in identifying the underlying kidney mass, which was higher than that (25%) of B-type ultrasound and (0) KUB + IVU. Radical nephrectomy was carried out in 6 cases, renal-reserved operation in 5, and conservative treatment in 5.

CONCLUSIONS

60% of spontaneous renal rupture are due to kidney neoplasia. CT scanning is the most valuable diagnostic procedure. If the primary cause has not been clarified, close follow-up with periodic CT scanning might be mandatory.

The T0 domain of rabbit KV1.3 regulates steady state channel protein level

The Shaker superfamily encodes voltage-gated potassium (Kv) channels. The amino (N) terminus is important for channel assembly and mediates fast inactivation. We recently isolated a Kv channel from rabbit kidney, denoted rabKv1.3 (Yao et al., J. Clin. Invest. 97, 2525-2533, 1996) and found that deleting a region (T0 domain, amino acids 3-39) proximal to the T1 recognition domain (a.a 42-185) leads to a 13-fold amplification of Kv current as compared to wild type channels (Yao et al., BBRC 249, 492-498). Here we show that deleting the T0 domain affects neither single channel conductance nor channel open probability. Instead, it increases the absolute number of channel proteins present in the membrane. We conclude that the T0 domain is a previously unrecognized Shaker Kv1.3, N-terminal regulatory region that modulates steady state channel protein density in the plasma membrane.

Rod-type cyclic nucleotide-gated cation channel is expressed in vascular endothelium and vascular smooth muscle cells

OBJECTIVES

Ca(++)-permeable nonselective cation channels mediate the entry of extracellular Ca++ in vascular endothelium. They are also partly responsible for Ca++ entry in vascular smooth muscle cells (SMCs). The molecular identities of these channels have not been identified. The aim of this study is to examine whether rod-type nucleotide-gated nonselective cation (CNG1) channel, a channel which has been molecularly cloned, is related to the nonselective channels in vascular cells.

METHODS

We used RT-PCR, molecular cloning, northern Blot and in situ hybridization to examine the expression of CNG1 mRNA in a variety of guinea pig and rat blood vessels with different diameters and in cultured vascular endothelial cells and vascular smooth muscle cells.

RESULTS

We have cloned a 402-bp partial cDNA of CNG1 channel from guinea pig mesenteric arteries. RT-PCR and southern blot results indicate that the CNG1 mRNA is expressed in both cultured vascular endothelial and cultured vascular SMCs. Northern blot revealed the transcripts of approximately 3.2 kb, approximately 5.0 kb, and approximately 1.8 kb in cultured endothelial cells. In situ hybridization yielded strong labeling in endothelium layer of aorta, medium-sized mesenteric arteries, and small mesenteric arteries.

CONCLUSION

Our findings suggest a potential role of CNG protein for Ca++ entry in vascular endothelium and vascular smooth muscles. The high expression of CNG1 mRNA in the endothelium of medium-sized arteries and small-sized arteries implicates a possible involvement of CNG1 protein in the regulation of blood supply to different regions and in the regulation of arterial blood pressure.

[Expression of P62c-myc protein in breast cancer and its clinical significance]

The objective of this study was to determine the clinical significance of P62c-myc protein expression in breast cancer. P62c-myc protein was detected in 107 patients with breast cancer by immunohistochemical techniques (LSAB). The results showed that the positive rate of P62c-myc protein expression was 63.55% (68/107). The overexpression of P62c-myc protein related negatively with survival. 94.00% of the cases with overexpression of P62c-myc protein survived < or = 5 years, 65.00% survived > 5 years-< 10 years, and 21.62% survived > or = 10 years. There were significant associations of P62c-myc expression with advance clinical stage, high histological grade, and positive axillary node status in breast cancers. All of these findings suggested that overexpression of P62c-myc might be an important prognostic factor, and the detection of P62c-myc protein might be arranged as a regular pathological examination in the cases of breast cancer.

[A clinical study on reducing immunologic rejection in combining corneal lamellar autografting with allografting]

OBJECTIVE

To reduce the rate of immunologic rejection, corneal lamellar autografting with allografting were combined, making immune cells less attack on allograft.

METHODS

The pterygium having encroached upon the pupillary area was removed surgically, and the combination of autograft with allograft was transplanted on the peripheral and central cornea in 23 cases (24 eyes). The control group of 13 cases (13 eyes) was established in which the pterygium and dermoids were removed, and lamellar allografts were transplanted. The rate of rejection and their effects were compared.

RESULTS

The rate of transparent autograft and allograft was 100%, no rejection and recurrence of pterygium occurred in any case in the combined group, while in the control group, the rejection rate was 30.8% and recurrence rate, 20.0%.

CONCLUSION

The combination of lamellar autografting with allografting can reduce the rate of rejection and recurrence of pterygium.

[Myocardial function after fluid resuscitation with addition of anisodamine in severely burned rabbits]

OBJECTIVE

To evaluate the effect of fluid resuscitation with addition of anisodamine (Ani) on myocardial function in severely burned rabbits.

METHODS

III degree burn injury covering 25% total body surface area (TBSA) was produced on rabbits. LVSP, LV +/- dp/dtmax were measured with fluid resuscitation alone, administration of Ani alone, and fluid resuscitation plus Ani before burn, immediately after burn and 1, 3, 5, 7 h after burn.

RESULTS

It was showed that myocardial contractility and relaxation were depressed 1 h after burn. Fluid resuscitation alone and administration of Ani alone could significantly improve myocardial contractility and relaxation only within 3 h postburn. With fluid resuscitation plus Ani (5 mg.kg-1), myocardial contractility and relaxation were improved statistically significantly as compared with control group without treatment (P < 0.01), with the values approaching the normal level.

CONCLUSION

Our data demonstrate that the administration of Ani (5 mg.kg-1) in addition to fluid resuscitation is beneficial to burn injury, especially to myocardial function, and it provides a promising approach for the future treatment of burns.

HERG potassium channel activation is shifted by phorbol esters via protein kinase A-dependent pathways

We investigated the effects of the phorbol ester phorbol 12-myristate 13-acetate (PMA) on the rapid component of the delayed rectifier potassium current, IKr, in guinea pig cardiomyocytes and found that the IKr current amplitude was reduced by 20% with 10 nM PMA and 44% with 100 nM PMA. The ether-a-go-go-related gene (HERG) encodes IKr in human heart. We expressed HERG heterologously in Xenopus oocytes and investigated the effects of PMA on the delayed rectifier potassium current. Upon application of PMA in a concentration of 100 nM, we found a similar reduction of HERG outward current amplitude by 59%. This reduction was due to a shift in the HERG activation curve by 37 mV. The ED50 for the PMA-induced shift was 9.0 nM. The inactive 4alpha-phorbol 12-myristate 13-acetate (4alpha-PMA) had no effect. PMA is known to act by stimulating distinct protein kinase cascades. Additional application of the specific protein kinase C inhibitors chelerythrine (10 microM) or bisindolylmaleimide (1 microM) could not attenuate the PMA-induced shift. In contrast, the shift by PMA was reduced significantly when the specific protein kinase A (PKA) inhibitors H89 (50 microM) or KT5720 (2.5 microM) were applied. Forskolin (400 microM), an activator of the adenylate cyclase that results in PKA activation, shifted the HERG activation curve by 14 mV. Moreover the specific protein kinase C activator 1-stearoyl-2-arachidonylglycerol (10 microM) showed no effect. Our data suggest that mainly PKA is mediating the shift of the HERG activation kinetics.

A K+ single channel and whole-cell clamp study on the effects of levocromakalim in guinea pig portal vein cells

Single channel cell-attached patch and whole-cell clamp experiments on the mode of action of the K+ channel opener (KCO), levcromakalim, were performed in guinea pig isolated portal vein cells. At +20 mV (135/23 mM K+ in bath/pipette), 10 microM levcromakalim activated K+ channels with a chord conductance of 23.2 pS (K(KCO)), which were sensitive to the blocker of ATP-dependent K+ channels (K(ATP)), glibenclamide. Voltage steps from -80 mV to +20 mV activated 4-aminopyridine-sensitive K+ channels of 6.5 pS with properties of delayed rectifier K+ channels (Kv). In patches which upon a previous voltage step had revealed the existence of Kv, levcromakalim reduced the open-probability of Kv, but it did not concomitantly activate K(KCO). During the course of the experiments, but unrelated to the presence of levcromakalim, large conductance K+ channels (BK(Ca)) appeared which could be inhibited by iberiotoxin, a selective blocker of BK(Ca), and by the membrane-permeant calcium buffer, BAPTA/AM, but not by glibenclamide. Whole-cell current-voltage (i-V) relations were established in response to voltage ramps from +50 mV to -100 mV; on subtraction of control i-V curves from i-V curves obtained in the presence of 10 microM levcromakalim, the KCO-induced K+ current remained which was proportional to voltage. This is not compatible with the upward-bent curvature predicted by the GHK current equation for purely resistive channels at high [K+]i versus low [K+]o. In conclusion, in the guinea pig portal vein cells, no evidence could be established for the hypotheses that KCOs may act via conversion of Kv to K(ATP) (Beech and Bolton 1989; Edwards et al. 1993) or by activation of BK(Ca) (Balwierczak et al. 1995). In these cells, mild inward rectification of the levcromakalim-induced current was observed which underlines their relationship to K(ATP) in other tissues.

Polyglutamine-expanded human huntingtin transgenes induce degeneration of Drosophila photoreceptor neurons

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder. Disease alleles contain a trinucleotide repeat expansion of variable length, which encodes polyglutamine tracts near the amino terminus of the HD protein, huntingtin. Polyglutamine-expanded huntingtin, but not normal huntingtin, forms nuclear inclusions. We describe a Drosophila model for HD. Amino-terminal fragments of human huntingtin containing tracts of 2, 75, and 120 glutamine residues were expressed in photoreceptor neurons in the compound eye. As in human neurons, polyglutamine-expanded huntingtin induced neuronal degeneration. The age of onset and severity of neuronal degeneration correlated with repeat length, and nuclear localization of huntingtin presaged neuronal degeneration. In contrast to other cell death paradigms in Drosophila, coexpression of the viral antiapoptotic protein, P35, did not rescue the cell death phenotype induced by polyglutamine-expanded huntingtin.

Reconstruction of the Jurassic conifer Sewardiodendron laxum (Taxodiaceae)

Compressed seed cones and pollen cones of Sewardiodendron laxum are described from the Middle Jurassic of Yima, Henan, central China. They are either organically attached to or associated with leafy shoots. Seed cones are terminally borne. Each cone is ovate to elongated, up to 6.5 cm long and 3.5 cm wide, and consists of a stout axis and numerous helically arranged bract-scale complexes. The bract protrudes beyond and is partially fused with the reduced ovuliferous scale. The ovuliferous scale bears approximately six inverted, small, and flattened seeds. Pollen cones are borne in terminal clusters. Microsporophylls are helically arranged, each bearing three abaxial, basally fused pollen sacs. Pollen is assaccate, rounded, and with an inconspicuous pore. Morphological, structural, and cuticular features of seed cones, pollen cones, and leafy shoots of S. laxum are compared with those of fossil and extant conifers. S. laxum is included in Taxodiaceae and believed to have its closest affinities with a Mesozoic conifer Elatides and a group of Cunninghamia-like conifers. It is reconstructed as a half-evergreen tree that lived in a humid, warm-temperate climate.

Nociceptin (ORL-1) and mu-opioid receptors mediate mitogen-activated protein kinase activation in CHO cells through a Gi-coupled signaling pathway: evidence for distinct mechanisms of agonist-mediated desensitization

The recently identified 17-amino acid peptide nociceptin (orphanin FQ) is the endogenous ligand for the opioid receptor-like-1 (ORL-1) receptor. A physiologic role for nociceptin (OFQ) activation of the ORL-1 receptor (OFQR) may be to modulate opioid-induced analgesia. The molecular mechanism by which nociceptin (OFQ) and ORL-1 (OFQR) modify opioid-stimulated effects, however, is unclear. Both ORL-1 (OFQR) and opioid receptors mediate pertussis toxin (PTX)-sensitive signal transduction, indicating these receptors are capable of coupling to Gi/Go proteins. This study determines that nociceptin stimulates an intracellular signaling pathway, leading to activation of mitogen-activated protein (MAP) kinase in CHO cells expressing ORL-1 receptor (OFQR). Nociceptin (OFQ)-stimulated MAP kinase activation was inhibited by PTX or by expression of the carboxyl terminus of beta-adrenergic receptor kinase (betaARKct), which specifically blocks Gbetagamma-mediated signaling. Expression of the proline-rich domain of SOS (SOS-PRO), which inhibits SOS interaction with p21ras, also attenuated nociceptin (OFQ)-stimulated MAP kinase activation. The phosphatidylinositol 3-kinase (PI-3K) inhibitors wortmannin and LY294002 reduced nociceptin (OFQ)-stimulated MAP kinase activation, whereas inhibition of protein kinase C (PKC) activity by bisindolylmaleimide I or cellular depletion of PKC had no effect. In a similar manner, in cells expressing mu-opioid receptor, [D-Ala2,N-Me-Phe4,Gly-ol]-enkephalin (DAMGO; a mu-opioid receptor-selective agonist) stimulated PTX-sensitive MAP kinase activation that was inhibited by wortmannin, LY294002, betaARKct expression, or SOS-PRO expression but not affected by inhibition of PKC activity. These results indicate that both ORL-1 (OFQR) and mu-opioid receptors mediate MAP kinase activation via a signaling pathway using the betagamma-subunit of Gi, a PI-3K, and SOS, independent of PKC activity. In cells expressing both ORL-1 (OFQR) and mu-opioid receptors, pretreatment with nociceptin decreased subsequent nociceptin (OFQ)- or DAMGO-stimulated MAP kinase activation. In contrast, pretreatment of cells with DAMGO decreased subsequent DAMGO-stimulated MAP kinase but had no effect on subsequent nociceptin (OFQ)-stimulated MAP kinase activation. These results demonstrate that nociceptin (OFQ) activation of ORL-1 (OFQR) can modulate mu-opioid receptor signaling in a cellular system.

Characterization of a regulatory region in the N-terminus of rabbit kv1.3

The N-terminus of rabbit Kv1.3 contains a signal sequence which regulates expression of Kv1.3 proteins in the plasma membrane. Removal of an N-terminal region (aa3-39) produced an increase in expressed K+ current. Progressive deletion at the N-terminus demonstrated that the shortest deletion required for the elevation of K current is D6-34. Since the functional signal sequence must include both ends of the peptide segment aa6-34 where charged residues are densely distributed, it is conceivable that this N-terminal signal sequence is related to charge or its associated hydrophilicity. Removal of two charged residues (31R, 33E) through amino acid substitution which converts deletion construct D3-27 to D3-27* effectively raises the amplitude of expressed current, further indicating the importance of charged residues. With the use of a mutated dynamin and a soluble N-terminal peptide, we also revealed that the N-terminal signal sequence may not act through the endocytotic pathway.

[An experimental study on the regenerating ability of the condylar cartilage of the rabbit]

OBJECTIVE

To investigate the regenerating ability of the condylar cartilage of the adult rabbit.

METHODS

A fullthickness defect was created in the condylar cartilage of the adult rabbit, with or without penetrating into the subchondral bone.

RESULTS

In the cases of the condylar cartilage defect without penetration into the subchondral bone, the defects were repaired with fibrous tissue partly. However, in those the defect penetrated the subchondral bone, the defects were repaired with cartilage-like tissue at four and eight weeks periods, then the regenerated tissue transformed into the bone-like tissue.

CONCLUSION

The defect of the condylar cartilage can't be repaired with cartilage, and the reparative cells were the undifferentiated mesenchymal cells originated from the bone marrow.