Development of Small-Molecule Anti-HIV-1 Agents Targeting HIV-1 Capsid Proteins

The capsid of human immunodeficiency virus type 1 (HIV-1) forms a conical structure by assembling oligomers of capsid (CA) proteins and is a virion shell that encapsulates viral RNA. The inhibition of the CA function could be an appropriate target for suppression of HIV-1 replication because the CA proteins are highly conserved among many strains of HIV-1, and the drug targeting CA, lenacapavir, has been clinically developed by Gilead Sciences, Inc. Interface hydrophobic interactions between two CA molecules via the Trp184 and Met185 residues in the CA sequence are indispensable for conformational stabilization of the CA multimer. Our continuous studies found two types of small molecules with different scaffolds, MKN-1 and MKN-3, designed by in silico screening as a dipeptide mimic of Trp184 and Met185 have significant anti-HIV-1 activity. In the present study, MKN-1 derivatives have been designed and synthesized. Their structure-activity relationship studies found some compounds having potent anti-HIV activity. The present results should be useful in the design of novel CA-targeting molecules with anti-HIV activity.

Low-molecular-weight anti-HIV-1 agents targeting HIV-1 capsid proteins

The HIV-1 capsid is a shell that encapsulates viral RNA, and forms a conical structure by assembling oligomers of capsid (CA) proteins. Since the CA proteins are highly conserved among many strains of HIV-1, the inhibition of the CA function could be an appropriate goal for suppression of HIV-1 replication, but to date, no drug targeting CA has been developed. Hydrophobic interactions between two CA molecules through Trp184 and Met185 in the protein are known to be indispensable for conformational stabilization of the CA multimer. In our previous study, a small molecule designed by in silico screening as a dipeptide mimic of Trp184 and Met185 in the interaction site was synthesized and found to have significant anti-HIV-1 activity. In the present study, molecules with different scaffolds based on a dipeptide mimic of Trp184 and Met185 have been designed and synthesized. Their significant anti-HIV activity and their advantages compared to the previous compounds were examined. The present results should be useful in the design of novel CA-targeting anti-HIV agents.

Small-Molecule Anti-HIV-1 Agents Based on HIV-1 Capsid Proteins

The capsid of human immunodeficiency virus type 1 (HIV-1) is a shell that encloses viral RNA and is highly conserved among many strains of the virus. It forms a conical structure by assembling oligomers of capsid (CA) proteins. CA dysfunction is expected to be an important target of suppression of HIV-1 replication, and it is important to understand a new mechanism that could lead to the CA dysfunction. A drug targeting CA however, has not been developed to date. Hydrophobic interactions between two CA molecules via Trp184/Met185 in CA were recently reported to be important for stabilization of the multimeric structure of CA. In the present study, a small molecule designed by in silico screening as a dipeptide mimic of Trp184 and Met185 in the interaction site, was synthesized and its significant anti-HIV-1 activity was confirmed. Structure activity relationship (SAR) studies of its derivatives were performed and provided results that are expected to be useful in the future design and development of novel anti-HIV agents targeting CA.

Difference in quasispecies of the hypervariable region 1 of hepatitis C virus between alcoholic and non-alcoholic patients

BACKGROUND

Habitual alcohol intake is known to aggravate the clinical outcome of hepatitis C virus (HCV)-related chronic liver diseases and to increase the risk of hepatocellular carcinoma.

METHODS

To investigate the possible mechanism of these effects by alcohol, we examined 31 cases of HCV-related chronic liver diseases of which 17 cases were drinking just before admission and the remaining 14 cases were non-drinkers. The studied cases included 18 patients with chronic hepatitis, six with liver cirrhosis and seven with hepatocellular carcinoma. The quasispecies of the hypervariable region 1 of the HCV genome were analyzed by using polymerase chain reaction single strand conformation polymorphism (PCR-SSCP). Hepatitis C virus viral load was quantitated by using multicyclic PCR after reverse transcription of the 5' non-coding region of the genome.

RESULTS

The mean PCR-SSCP band number that reflected the quasispecies complexity in hypervariable region 1 was more significantly increased in alcoholics than in non-alcoholics (5.5 +/- 1.4 vs 3.9 +/- 1.1, P< 0.01). The significant increase in alcoholics remained, even if the cases were restricted to males (P < 0.01), to HCV genotype 1b (P < 0.05) or to chronic hepatitis (P < 0.05). The HCV viral load was not statistically different between alcoholic and non-alcoholic HCV-related chronic liver diseases (5.02 x 10(6) +/- 5.16 x 10(6) copies/mL vs 9.00 x 10(7) +/- 2.75 x 10(8) copies/mL, P = 0.28). Mutation events seemed to occur randomly when amino acid sequences of hypervariable region 1 were compared between four drinkers and four non-drinkers.

CONCLUSIONS

The enhanced quasispecies complexity in hypervariable region 1 of HCV in alcoholics may be the main cause of more progressive HCV-related chronic liver diseases, and may provide the disease the resistance against any therapeutic modalities including interferon.

OUT, a novel basic helix-loop-helix transcription factor with an Id-like inhibitory activity

Transcription factors belonging to the basic helix-loop-helix (bHLH) family are involved in various cell differentiation processes. We report the isolation and functional characterization of a novel bHLH factor, termed OUT. OUT, structurally related to capsulin/epicardin/Pod-1 and ABF-1/musculin/MyoR, is expressed mainly in the adult mouse reproductive organs, such as the ovary, uterus, and testis, and is barely detectable in tissues of developing embryos. Physical association of OUT with the E protein was predicted from the primary structure of OUT and confirmed by co-immunoprecipitation. However, unlike other bHLH factors, this novel protein failed to bind E-box or N-box DNA sequences and inhibited DNA binding of homo- and heterodimers consisting of E12 and MyoD in gel mobility shift assays. In luciferase assays, OUT inhibited the induction of E-box-dependent transactivation by MyoD-E12 heterodimers. Deletion studies identified the domain responsible for the inhibitory action of OUT in its bHLH and C-terminal regions. Moreover, terminal differentiation of C2C12 myoblasts was inhibited by exogenous introduction of OUT. These inhibitory functions of OUT closely resemble those of the helix-loop-helix inhibitor Id proteins. Based on these findings, we propose that this novel protein functions as a negative regulator of bHLH factors through the formation of a functionally inactive heterodimeric complex.

Enhanced expression of interleukin-6 in chronic hepatitis C

AIMS/BACKGROUND

There is a possibility that proinflammatory cytokines such as interleukin-6 (IL-6) are involved in the inflammatory process of chronic hepatitis C. This study was undertaken to investigate the possible role of IL-6 in the pathophysiology of chronic hepatitis C.

METHODS

Serum IL-6 levels in 63 patients with chronic hepatitis C and in 26 normal controls were measured. Light and electron immunostaining studies to localize IL-6 protein as well as in situ hybridization to localize IL-6 messenger RNA were performed on 10 liver biopsy specimens.

RESULTS

Serum IL-6 levels were significantly (p<0.01) elevated in chronic hepatitis C compared to those in normal controls. Although no statistically significant correlation was found between serum IL-6 levels and hepatobiliary enzyme levels, a significant correlation (p<0.01) was found between serum IL-6 levels and category II of Knodell's histological activity index score. Non-parenchymal cells in hepatic sinusoids and the cells infiltrating enlarged fibrous portal tracts were definitely positive for IL-6 protein and mRNA by immunohistochemistry and in situ hybridization. In addition, immunoelectron microscopy revealed a weak and occasional positive reaction in the cytoplasm of hepatocytes. The majority of the positive cells in hepatic sinusoids showed CD68 immunoreactivity in consecutive sections indicating that these were Kupffer cells. Sinusoidal endothelial cells and hepatic stellate cells also exhibited a weak reaction.

CONCLUSION

These results strongly suggest that Kupffer cells in liver parenchyma and macrophages infiltrating in portal tracts are the main producers of elevated IL-6 in serum. Moreover, there is a possibility that IL-6 produced by hepatocytes could also act as a regenerative stimulus to hepatocytes themselves in an autocrine fashion.

Signaling from Rho to the actin cytoskeleton through protein kinases ROCK and LIM-kinase

The actin cytoskeleton undergoes extensive remodeling during cell morphogenesis and motility. The small guanosine triphosphatase Rho regulates such remodeling, but the underlying mechanisms of this regulation remain unclear. Cofilin exhibits actin-depolymerizing activity that is inhibited as a result of its phosphorylation by LIM-kinase. Cofilin was phosphorylated in N1E-115 neuroblastoma cells during lysophosphatidic acid-induced, Rho-mediated neurite retraction. This phosphorylation was sensitive to Y-27632, a specific inhibitor of the Rho-associated kinase ROCK. ROCK, which is a downstream effector of Rho, did not phosphorylate cofilin directly but phosphorylated LIM-kinase, which in turn was activated to phosphorylate cofilin. Overexpression of LIM-kinase in HeLa cells induced the formation of actin stress fibers in a Y-27632-sensitive manner. These results indicate that phosphorylation of LIM-kinase by ROCK and consequently increased phosphorylation of cofilin by LIM-kinase contribute to Rho-induced reorganization of the actin cytoskeleton.

Expression, localization and alternative splicing pattern of fibronectin messenger RNA in fibrotic human liver and hepatocellular carcinoma

BACKGROUND/AIMS

Fibronectin is a multifunctional glycoprotein and plays important roles in cell-to-cell or cell-to-matrix interaction. The molecular and functional diversity of fibronectin arises from alternative splicing of pre-mRNA at three variable regions, termed ED-A, ED-B and IIICS. Cellular fibronectin with ED-A and ED-B regions has different biological activities from plasma fibronectin lacking these regions. This study was aimed at investigating the type-specific expression of fibronectin in human liver diseases.

METHODS

Immunohistochemistry with anti-total and anti-cellular fibronectin monoclonal antibodies, in situ hybridization with cDNA probes detecting common and ED-A regions and RT-PCR to amplify each variable region were performed in 35 specimens, including 4 control, 16 chronic hepatitis, 7 liver cirrhosis and 8 hepatocelular carcinoma.

RESULTS

In control liver, there were slight deposits of cellular fibronectin [ED-A(+)fibronectin] in portal areas. In chronic hepatitis, it was strongly deposited at the margin of the fibrously enlarged portal areas where new collagen fibers were formed. Cellular fibronectin was evenly and abundantly accumulated in fibrotic septa in liver cirrhosis, and in fibrotic septa and capsules of tumor nodules in hepatocellular carcinoma. In control liver, cellular fibronectin mRNA was localized in a few hepatocytes and non-parenchymal cells around central veins, and was increased in the same cell populations near fibrously enlarged portal areas as hepatic fibrosis progressed. In hepatocellular carcinoma, it was expressed in most hepatoma cells. Fibronectin mRNA with three variable regions was detectable by RT-PCR in control liver as well as in each disease group.

CONCLUSIONS

The expression of cellular fibronectin was increased in fibrotic human liver and hepatocellular carcinoma. In human liver, both non-parenchymal cells and hepatocytes participated together in cellular fibronectin production. In hepatocellular carcinoma, hepatoma cells were the main producer. Our results indicate that, in human liver, cellular fibronectin may participate in the hepatic fibrogenesis and in the malignant phenotypes of hepatocellular carcinoma.

[A role of platelet activating factor in experimental hemorrhagic enteritis induced by Clostridium difficile toxin]

Clostridium difficile is thought to be an important causative agent of antibiotics associated colitis. However its mechanisms are not fully understood. The present study was designed to elucidate the effect of PAF and free radicals on experimental hemorrhagic enteritis induced by Clostridium difficile toxin. PAF concentration in the portal blood and accumulated fluid, disturbance of the vascular endothelial cells in the ligated jejunal loops and chemiluminescence activity of WBC in the control group's rats increased from 4 hrs over 10 hrs after the administration of Clostridium difficile toxin. On the other hand, the amount of fluid accumulation, protein concentrations in the accumulated fluids, histological changes in the ligated jejunal loops of toxin administered rats and chemiluminescence activity of WBC were significantly suppressed by PAF antagonist (CV6209:TAKEDA). These results suggest that PAF and free radicals may have some role in microcirculatory disturbance and hyperpermeability of the blood vessels in the intestine of hemorrhagic enteritis induced by Clostridium difficile toxin.

[Clinicopathological significance of immune complex (IC) along the tubular basement membrane (TBM) in lupus nephritis]

This paper reports on the clinicopathological significance of IC along the TBM in lupus nephritis. Renal biopsies were performed on 60 patients with SLE. All of the patients demonstrated immunoglobulin deposits in the glomeruli, and 16 of them also showed immune deposits along the TBM. The IgG in the glomeruli or along the TBM completely disappeared after incubation with human IgG, IgG Fc fragments, but not with human F(ab')2, rabbit or rat IgG. These results suggest that IgG along the TBM are similar in nature to IC in the glomeruli and that the IC are composed of IgG rheumatoid factor. The square of tubulointerstitial lesions was more severe in the group with IgG along the TBM than in the group with no IgG along the TBM (5.85 +/- 9.88% vs 1.29 +/- 3.72%). In addition of this, the group with IgG deposits along the TBM frequently demonstrated type IV lupus nephritis. Although the renal function was not significantly different in the both groups, the serum complement level was lower in the cases with IC deposits in the TBM. From these results, it is suggested that IC deposits along the TBM as one of the important inflammatory agents lead to the severe forms of tubulointerstitial injury and show the active stage of the disease in SLE patients.

[Involvement of allergic mechanism in minimal change nephrotic syndrome (MCNS)]

In this study we evaluated the involvement of allergic mechanisms in patients with adult onset MCNS (17 cases) by measuring serum IgE levels and RAST scores to house dust 1 (H.D.1), house dust 2 (H.D.2), Dermatophagoides farinae (D.f.), Dermatophagoides ptenonyssinus (D.p.). Out of the 17 cases, three cases showed high levels of IgE (more than 1000 IU/ml) and the mean level of serum IgE was 877 IU/ml before treatment. All cases were treated with steroid and/or cyclophosphamide. After the treatment, all cases returned to remission. The level of IgE decreased to the normal range in four out of seven cases which had shown high levels of IgE before treatment. RAST was carried out on seven of the 17 cases. RAST scores for D.f. and D.f. were found to be positive in three cases, but these became negative in two cases after treatment. In five cases relapsed, the all cases showed to have the increased level of serum IgE and two of four cases which were examined RAST score showed to have the increased RAST score for D.f. and D.p. Thus, the data indicated that allergic mechanism, especially against D.f. and D.p. antigen, seemed to play one of the factors in the pathogenesis of MCNS.

[Two cases of renovascular hypertension detected by 2-D Doppler method]

Renovascular hypertension is most frequent causes of secondary hypertension. Although angiography of renal artery is reliable procedure for the diagnosis of the renovascular hypertension, it is expensive and invasive. We report two cases which become possible to make diagnosis of the renovascular hypertension by measurement of velocity of segmental or interlobar artery using 2-D color Doppler method. Case 1: 39 year-old male was hospitalized because of hypertension (200/130 mmHg). Ccr was 82 ml/min. 2-D Doppler test demonstrated that the Vmax, the Vmin and the Vmin/Vmax of the right segmental artery were 40 cm/sec., 24 cm/sec. and 0.60, respectively. The Vmax, the Vmin, and the Vmin/Vmax of the left segmental artery were 42 cm/sec., 22 cm/sec. and 0.52, respectively. Renal angiography shows right renovascular stenosis. After percutaneous transluminal angioplasty, the blood pressure became normal and Vmin/Vmax ratio of the right segmental artery was down to 0.52. Case 2: 46 year-old male was hospitalized because of chronic renal failure (Ccr: 14.6 ml/min) and uncontrollable hypertension. 2-D Doppler test demonstrated that the Vmax, the Vmin, the Vmin/Vmax ratio and the acceleration of the right segmental artery were 10 cm/sec., 6 cm/sec., 0.62 and 1.7 m/sec.2, respectively. The Vmax, the Vmin, the Vmin/Vmax ratio and the acceleration of the left interlobar artery were 8 cm/sec., 5 cm/sec., 0.63 and 0.8 m/sec.2, respectively. Renal angiography shows bilateral renovascular stenosis. Thus, the elevated value of Vmin/Vmax ratio (over 0.6) (mean value: 0.43 +/- 0.08, when Ccr is over 70 ml/min, whereas 0.32 +/- 0.11, when Ccr is under 30 ml/min) and decreased acceleration (under 2.0 m/sec. 2) of the segmental or the interlobar artery seems to be helpful for the diagnosis of renovascular hypertension.

Evaluation of alaryngeal voice quality by nonparametric procedures

Alaryngeal voice quality was evaluated based on nonparametric statistics. Twenty voice samples of the vowel /e/ were recorded from sixteen alaryngeal and four normal speakers, and were randomized and presented to twenty normal listeners. The listeners rated the voices using seven-point scales consisting of twelve pairs of polar-opposite adjectives. By means of nonparametric procedures such as the Wilcoxon signed rank test, significant differences in the rating scores were detected for certain combinations of the voice samples, the classes of voicing methods, the listeners and the rating scales. Quality of the alaryngeal voices differed significantly from that of the normal voices on some of the rating scales. The results suggest the nonparametric procedures are useful to evaluate alaryngeal voice quality.

[The effect of enzymes on progesterone-receptor binding and chromatin binding of the complex in the estrogen-primed rabbit uterus (author's transl)]

The present study was designed to determine the characteristics of the progesterone receptor and chromatin binding site ("acceptor") of the progesterone-receptor complex in the rabbit uterus. The uterus was obtained from an estrogen-primed immature female rabbit. The binding of progesterone to the uterine receptor was examined in vitro. The progesterone-receptor binding was reduced only by proteases, and phosphorus moiety may not be related for progesterone-receptor binding. The effects of enzymes on the acceptor of the chromatin were investigated. The progesterone-receptor complex was bound to the dehistonized chromatin. The dehistonized chromatins, which were pretreated with enzymes at 4 degrees C or 37 degrees C for 30 minutes, were incubated with 3H-progesterone prelabeled uterine cytosol at 4 degrees C for 30 minutes, and the radioactivity in the chromatin pellet was counted. Proteases effectively decreased the receptor binding capacity to the dehistonized chromatin in the following order: pronase greater than trypsin greater than papain greater alpha-chymotrypsin. DNAse moderately and phospholipase A slightly decreased its binding capacity. The results may indicate that the acceptor site of the progesterone receptor is nonhistone protein over DNA of chromatin and may contain phosphorus moiety.

Preliminary studies on streoid-binding proteins in human testes of testicular feminization syndrome

This study was designed to detect either 5alpha-dihydrotestosterone (DHT) or 17beta-estradiol (E2)-binding protein in the testes of a 1-year-old patient with testicular feminization syndrome (TFS) and in the testes of patients with prostatic cancer. Sucrose gradient analyses revealed E27S protein binding (but no such 7S protein binding of DHT) in the testes of the patient with TFS, but both E2 and DHT 7 S protein binding was observed in normal senile testes. The dissociation constants (Kd) were measured by charcoal adsorption. The Kd of E2 protein binding in both testes of different status was approximately 1.3 x 10(-9) M, and the Kd of DHT protein binding was 2.0 x 10(-9) M in the senile testes. A ligand specificty study indicated characteristics of both E2 and DHT receptors in the senile testes. It is speculated that a deficiency of androgen receptor and the presence of estrogen receptor in the testes of patients with TFS lead to insensitivity to androgen as a result of the androgen receptor deficiency and to sensitivity to estrogen as a result of the presence of the estrogen receptor.

Progesterone receptor in human endometrium of leiomyoma uteri

This study was designed to examine whether 8S protein as progesterone receptor exists in the human endometrium which has been primed with estrogen. The kinetic study showed that 8S-progesterone binding was specific with Kd of 2.0 X 10(-9) M. 5S-progesterone binding was inhibited competitively by cortisol. The study of ligand specificity also showed that progesterone and its related steroids had much stronger affinity for 8S component than for 5S component. Therefore, 5S protein may be CBG. Progesterone-8S protein binding was easily dissociated during the 5-20% sucrose gradient centrifugation, but such a protein from which progesterone had been dissociated could be sedimented at 8S region. Glycerol could stabilize progesterone-8S protein binding. These results indicate the existence of 8S protein as a progesterone receptor under the low salt medium in the estrogen primed human endometrium.

Zymogram analyses of various organs, glands and tissues from spontaneously hypertensive rats (SHR) and DOCA hypertensive rats

Esterase and Acid phosphatase isozymes were examined in a number of organs, glands and tissues from Spontaneously Hypertensive Rats (SHR) and kidney and liver from DOCA hypertensive rats at various stages in comparison with those of normotensive rats (CR). In SHR, the abnormalities in the patterns of esterase isozyme were demonstrated in endocrine glands and respiratory tracts as well as in the kidney, liver and digestive tracts throughout the whole life span, and abnormalities in the patterns of acid phosphatase isozyme was also demonstrated in the liver after seven days of age. Moreover, in DOCA hypertensive Rats, minute alterations in esterase isozyme were demonstrated in the kidney and liver after seventh month of the duration of hypertension.