Synthesis of polyamine derivatives having non-hypotensive Ca2 +-permeable AMPA receptor antagonist activity

In order to obtain non-hypotensive and Ca2+-permeable AMPA receptor antagonists, we have synthesized a series of 1,4-bis(4-piperidinylmethyl)diaminobutanes. Compounds 13b, c, f had desirable properties.     

Baculovirus GP64-mediated entry into mammalian cells

The baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) serves as an efficient viral vector, not only for abundant gene expression in insect cells, but also for gene delivery into mammalian cells. Lentivirus vectors pseudotyped with the baculovirus envelope glycoprotein GP64 have been shown to acquire more potent gene transduction than those with vesicular stomatitis virus (VSV) envelope glycoprotein G. However, there are conflicting hypotheses about the molecular mechanisms of the entry of AcMNPV. Moreover, the mechanisms of the entry of pseudotyped viruses bearing GP64 into mammalian cells are not well characterized. Determination of the entry mechanisms of AcMNPV and the pseudotyped viruses bearing GP64 is important for future development of viral vectors that can deliver genes into mammalian cells with greater efficiency and specificity. In this study, we generated three pseudotyped VSVs, NPVpv, VSVpv, and MLVpv, bearing envelope proteins of AcMNPV, VSV, and murine leukemia virus, respectively. Depletion of membrane cholesterol by treatment with methyl-β-cyclodextrin, which removes cholesterol from cellular membranes, inhibited GP64-mediated internalization in a dose-dependent manner but did not inhibit attachment to the cell surface. Treatment of cells with inhibitors or the expression of dominant-negative mutants for dynamin- and clathrin-mediated endocytosis abrogated the internalization of AcMNPV and NPVpv into mammalian cells, whereas inhibition of caveolin-mediated endocytosis did not. Furthermore, inhibition of macropinocytosis reduced GP64-mediated internalization. These results suggest that cholesterol in the plasma membrane, dynamin- and clathrin-dependent endocytosis, and macropinocytosis play crucial roles in the entry of viruses bearing baculovirus GP64 into mammalian cells.     

High doses of ultraviolet-C irradiation increases vasoactive intestinal contractor/endothelin-2 expression in keratinocytes of the newborn mouse epidermis

We examined the expression profiles of vasoactive intestinal contractor/endothelin-2 (VIC/ET-2) at both gene and peptide level in skin irradiated with different ultraviolet wavelengths. We found that VIC/ET-2 gene expression is sensitive only to ultraviolet-C (UVC) irradiation and has an immediate response. These results provide direct evidence that high doses of UVC irradiation induce an increase in gene expression and protein production of VIC/ET-2 and endothelin (ET) receptors in a dose-dependent manner in epidermal keratinocytes. We suggest that VIC/ET-2 can play an essential role in the maintenance, protection and hyperpigmentation of the epidermis exposed to UVC irradiation from artificial or natural sources.     

Functional association between nicotinic acetylcholine receptor and sarcomeric proteins via actin and desmin filaments

By affinity chromatography utilizing alpha-cobrotoxin from digitonin-solubilized fractions of rabbit skeletal muscle, we found that many proteins are associated with the nicotinic acetylcholine receptor (AChR). In addition to the proteins we previously reported to bind to AChR (including dystrophin-dystrophin-associated protein (DAP) complex, utrophin, rapsyn, and actin; Mitsui et al. [1996] Biochem. Biophys. Res. Commun.224:802-807), alpha-actinin, desmin, myosin, tropomyosin, troponin T, and titin are also identified to be associated with AChR. Alkaline treatment or Triton X-100 solubilization released dystrophin-DAP complex, utrophin, and rapsyn from the AChR fraction, while actin and desmin remained associated. These findings demonstrate that AChR is supported primarily by a submembranous organization of actin and desmin filaments, and is linked to sarcomeric proteins via these filaments. To further investigate whether the association has any functional role, we studied the effect of acetylcoline on ATPase activity of the AChR fraction. Acetylcholine (0.5-4 microM) significantly activated Mg(2+)-ATPase activity of digitonin-solubilized AChR fraction (P < 0.05). Furthermore, we found that desmin as well as actin activated myosin Mg(2+)-ATPase activity. From these findings, it is suggested that desmin and actin form a submembranous organization in the postsynaptic region, and function as mediators of excitation of AChR to the sarcomeric contraction system.     

Rip locus: regulation of female-specific isozyme (I-P-450(16 alpha) of testosterone 16 alpha-hydroxylase in mouse liver, chromosome localization, and cloning of P-450 cDNA

The constitutive expression of phenobarbital-inducible mouse cytochrome P-450 (I-P-450(16 alpha) at the mRNA level and its associated testosterone 16 alpha-hydroxylase activity in liver microsomes was a female characteristic in many inbred mice, including BALB/cJ, A/HeJ, and C57BL/6J. This sex-dependent constitutive expression of the mRNA and enzyme activity was severely reduced in females of mouse strain 129/J. The distribution patterns of the mRNA and activity levels in individual offspring of F1, F2, and F1 backcrosses to progenitors, generated from crosses between 129/J and BALB/cJ mice, indicated that the female-specific expression of I-P-450(16 alpha) is an autosomal dominant trait under the regulation of a sex-limited single locus. It was found that the genotypes of this locus exhibited concordance with that of the coumarin hydroxylase locus (Coh locus) in eight out of nine 9 X A recombinant inbred strains, suggesting the localization of this sex-limited locus on chromosome 7. We propose Rip (regulation of sex-dependent, constitutive expression of phenobarbital-inducible P-450) as the name of this sex-limited locus. With the use of the rat P-450e cDNA probe, a cDNA library from liver poly(A+) RNA of BALB/cJ was screened, and three distinct cDNAs (pf3, pf26, and pf46) were selected on the basis of their restriction patterns. Nucleotide sequences of the cDNAs revealed that pf3 and pf46 are clones overlapped, with the exception that the 27-bp DNA is inserted in the coding region of pf46. The nucleotide sequence (named pf3/46) obtained from the overlapping sequences of pf3 and pf46 contained 1473 or 1500 bp of open-reading frame, and the deduced amino acid sequence shared 93% similarity with those of rat P-450b. The 27-bp insertion resulted in nine extra amino acids just in front of the cysteine residue, the fifth ligand for heme binding. The mRNA with 27-bp insertion was ubiquitously present in other inbred mice such as A/HeJ and C57BL/6J, but not in 129/J. S-1 nuclease analysis estimated a ratio of p46 and pf3 to be 1:50. Nucleotide and deduced amino acid sequences of the 1473-bp open-reading frame in pf26 possessed 83% similarity to those of pf3/46. Hybridizations of oligonucleotide probes (pf26-cu and pf3/46-cu) specific to either pf26 or pf3/46 with liver poly(A+) RNA from males and females of BALB/cJ, 129/F, and F1 offspring demonstrated that the expression of pf26, but not pf3/46, mRNA was associated with the autosomal dominant inheritance of I-P-450(16 alpha).(ABSTRACT TRUNCATED AT 400 WORDS)     

Contraction and intracellular calcium-ion elevation of cultured human aortic smooth muscle cells by endothelin-1, vasoactive intestinal contractor (VIC) and the derivatives

Summary Effects of endothelin (ET) family peptides and their derivatives on cellular contraction and calcium-ion level were examined by using cultured human vascular smooth muscle cells (VSM). Contraction of cultured human VSM, isolated from human fetal aortic segments, was induced within 1 min after the treatment with ET-1 (100 nM) as seen in the changes of cytosolic calcium-ion localization. In parallel with the cell contraction, cytosolic calcium-ion level in the human VSM increased very rapidly and then dropped with some oscillation as determined by Anchorage Cell Analyzing System. It was noted that transient calcium-ion mobilization rather than sustained calcium-ion influx was significant in the contraction of cultured human VSM. Vasoactive intestinal contractor (VIC), three amino acids different from ET-1, had less activity in increase of intracellular calcium-ion level and in percent of response cells than ET-1, ET-2, and VIC-S4L6 (one amino acid different from ET-1). EC₅₀ of ET-1, VIC-S4L6, ET-2, and VIC were 0.5 nM, 0.6 nM, 2.0 nM, and 20 nM, respectively. VIC-like peptide (VIC-LP), 16 amino acids fragment of VIC precursor protein, had no effect with a single administration of up to 10 μM. However, the increase in calcium-ion level by VIC was suppressed with a prior treatment of cells with high concentration (10 μM) of VIC-LP. The establishment of cultured human VSM for the simultaneous examination of the contraction and calcium-ion level will provide a new system to study signal transduction of vasocontractor peptides.