Alteration of Levels of Cyclic Nucleotide and Analysis of SDS-PAGE in Autologous Transplanted Spleen and Splenic Artery Ligation

Intracellular levels of cyclic nucleotide were detected and mitogen stimulation assays were performed in young Sprague-Daewley rats and suspension of spleen tissue were separated by SDS-PAGE. Results indicated that intracellular levels of cyclic AMP in transplanted cell were significantly lower compared to the control group(P<0.01), the levels of cyclic GMP in transplant cell and the levels of cyclic nucleotide in splenic artery ligation groups were normal. Immunologic tests showed that the stimulation index by Con A for T cells was drastically decreased in the autotransplant and a normal proliferation of B cells after LPS stimulation in transplants. Electrophoresis showed differences in the protein patterns between both tissues. Mitogen stimulation and the protein patterns were not different between the control and splenic artery ligation groups. There were differences between the normal tissues and the transplants at the functional level, Suggesting simple autotransplant can not prevent overwhelming postsplenectomy infection. The intact cellular function after splenic artery ligation indicated that its anti-infection ability is superior to that of splenic transplants.

Relaxant effect and possible mechanism of 17-nor-subincanadine E in rabbit corpora cavernosa

Compounds with dual action on cyclic adenosine monophosphate （cAMP） and cyclic guanosine monophosphate （cGMP） may be a treatment option for erectile dysfunction, as they not only promote penile erection but also prevent the upregulation of phosphodiesterase-5. In this study, we examined the possible relaxant effect and mechanism of 17-nor-subincanadine E （SEC, 0.2-200 pmol I^-1）, a plant-derived alkaloid, in rabbit corpus cavernosum （RbCC） strips that had been precontracted by exposure to phenylephrine （10 pmol I^- 1） or a high concentration of K＋ （60 mmol I^- 1） in vitro. In addition to SEC＇s effect on cAMP and cGMP levels, electrical field stimulation （EFS） in phenylephrine-precontracted RbCC and calcium chloride （1-100 mmol I^-1） evoked responses in depolarized RbCC were analysed. SEC relaxed the phenylephrine-precontracted RbCCs in a concentration-dependent manner. Atropine, guanethidine and N-co-nitro-L-arginine methyl ester （L-NAME） did not have any effect on the relaxation of RBCCs. When 1H-1,2,4oxadiazole[4,3-a] quinoxalin-1-one （ODQ） was added, it effectively blocked the relaxant response of SEC. Although SEC enhanced the maximal relaxation produced by sodium nitroprusside （SNP） and forskolin in phenylephrine-precontracted cavernosal smooth muscle, it caused a decrease in the maximal contractile response induced by calcium chloride in depolarized RbCCs. The relaxant effect of SEC was paralleled by an increase in the tissue levels of the Cyclic nucleotides cAMP and cGMP. We conclude that SEC promotes the relaxation of RbCC, possibly favouring cAMP and cGMP accumulation and calcium blockade. This novel mechanism could be useful for patients who do not benefit from phosphodiesterase inhibitors and for those with endothelial and nitrergic dysfunction, such as patients with diabetes, hypertension and dyslipidaemias.

The Quantum-Mechanical Sensitive Na/K Pump Is a Key Mechanism for the Metabolic Control of Neuronal Membrane Function

At present, there are relevant scientific materials on the cellular and molecular mechanisms of electrogenic Na/K pump function and structure, as well as on the potential- and ligand-activated ionic channels in the membrane. However, the role of electrogenic Na/K pump in regulation of semipermeable properties of cell membrane has not been elucidated yet, which is due to the fact that our knowledge about the biophysical properties of cell membrane is based on the conductive membrane theory of Hodgkin-Huxley-Katz, which is developed on internally perfused squid axon and lacks intracellular metabolism. Thus, the accumulated abundance of data on the role of G-proteins-dependent intracellular signaling system in regulation of Na/K pump activity and biophysical properties of cell membrane presumes fundamental revision of some statements of membrane theory. The aim of the present review is to briefly demonstrate our and literature data on cell hydration-induced auto-regulation of Na/K pump as well as on its role in metabolic control of semipermeable properties and excitability of neuronal membrane, which are omitted in the study of internally perfused squid axon.

Molecular Yin and Yang of erectile function and dysfunction

In regard to erectile function, Yin is flaccidity and Yang erection. In the past decade, research has mostly focused on the Yang aspect of erectile function. However, in recent years, the Yin side is attracting increasingly greater attention. This is due to the realization that penile flaccidity is no less important than penile erection and is actively maintained by mechanisms that play critical roles in certain types of erectile dysfunction （ED）; for example, in diabetic patients. In addition, there is evidence that the Yin and Yang signaling pathways interact with each other during the transition from flaccidity to erection, and vice versa. As such, it is important that we view erectile function from not only the Yang but also the Yin side. The purpose of this article is to review recent advances in the understanding of the molecular mechanisms that regulate the Yin and Yang of the penis. Emphasis is given to the Rho kinase signaling pathway that regulates the Yin, and to the cyclic nucleotide signaling pathway that regulates the Yang. Discussion is organized in such a way so as to follow the signaling cascade, that is, beginning with the extracellular signaling molecules （e.g., norepinephrin and nitric oxide） and their receptors, converging onto the intracellular effectors （e.g., Rho kinase and protein kinase G）, branching into secondary effectors, and finishing with contractile molecules and phosphodiesterases. Interactions between the Yin and Yang signaling pathways are discussed as well.

Leber's congenital amaurosis and the role of gene therapy in congenital retinal disorders

Leber＇s congenital amaurosis（LCA）and recent gene therapy advancement for treating inherited retinopathies were extensive literature reviewed using MEDLINE,Pub Med and EMBASE. Adeno-associated viral vectors were the most utilised vectors for ocular gene therapy. Cone photoreceptor cells might use an alternate pathway which was not reliant of the retinal pigment epithelium（RPE）derived retinoid isomerohydrolase（RPE65）to access the 11-cis retinal dehydechromophore. Research efforts dedicated on the progression of a gene-based therapy for the treatment of LCA2. Such gene therapy approaches were extremely successful in canine,porcine and rodent LCA2 models. The recombinant AAV2.h RPE65v2 adenoassociated vector contained the RPE65 cDNA and was replication deficient. Its in vitro injection in target cells induced RPE65 protein production. The gene therapy trials that were so far conducted for inherited retinopathies have generated promising results. Phase I clinical trials to cure LCA and choroideremia demonstrated that adeno-associated viral vectors containing RPE genes and photoreceptors respectively,could be successfully administered to inherited retinopathy patients. A phase III trial is presently ongoing and if successful,it will lead the way to additional gene therapy attempts to cure monogenic,inherited retinopathies.

Identification of novel cyclic nucleotide phosphodiesterase gene cDNAs in the brain of guinea pig

Objective Cyclic nucleotide phosphodiesterase（PDE）is a critical component of the nitric oxide（NO）signaling pathway and plays critical roles in cognition and learning,Parkinson’s disease,attention deficit hyperactivity disorder, psychosis and depression.The PDEs in the brain of guinea pig have not yet been reported.The present study aimed to detect the unknown Pde cDNAs in the brain of guinea pig.Methods Reverse transcription polymerase chain reaction（RT-PCR）and sequence comparison analysis were performed to detect the expression of Pde cDNAs and to assess the identity rates of cDNA and amino acid sequences between guinea pig and human or mouse,respectvely.The RT-PCR primers were located on the conserved region of human PDE and mouse Pde cDNAs.Results Eleven novel Pde cDNAs were detected in the brain of guinea pig（Cavia porcellus）,including CpPde1a,CpPde1b,CpPde2a,CpPde4a,CpPde4d,CpPde5a,CpPde6c,CpPde7b, CpPde8a,CpPde9a,and CpPde10a.The identity rates of the Pde cDNA sequences between guinea pig and human ranged from 83.8%to 94.3%,and those of the amino acid sequences ranged from 91.9%to 100%.The identity rates of Pde cDNA sequences between guinea pig and mouse ranged from 84.6%to 92.1%,and those of amino acid sequences ranged from 91.2% to 99.2%.The average identity rate of the 11 Pde cDNA sequences between guinea pig and human was significantly higher（P 0.01）than that between guinea pig and mouse.The putative partial amino acid sequences of guinea pig contained at least one of the conserved domains of human and mouse PDE proteins.Conclusion These results indicate that the brainexpressed Pde genes are identified in guinea pig,which lays the foundation for further investigating the physiological roles of PDE proteins in the brain.

Mechanism involved in the modulation of photoreceptor-specific cyclic nucleotidegated channel by the tyrosine kinase adapter protein Grb14

We recently found that growth factor receptor-bound(Grb)protein 14 is a novel physiological modulator of photoreceptor specific cyclic nucleotide-gated channel alpha subunit(CNGA1).Grb14 promotes the CNG channel closure through its Ras-associating(RA)domain.In the current study we show that this RA domain-mediated inhibition of rod CNG channel is electrostatic in nature.Grb14 competes with cGMP for the CNGA1 binding pocket and electrostatically interacts with Arg^(559) through a negatively chargedβ-turn at its RA domain.Moreover,the three Glu residues(180–182)in Grb14 are absolutely critical for electrostatic interaction with the cGMP binding pocket and resultant inhibition.Our study also demonstrates that substitution of Lys^(140) for Ala or in combination with polyglutamte mutants of Grb14 results in a significantly reduced binding with CNGA1.These results suggest that in addition to Glu^(180–182) and Lys^(140),other residues in Grb14 may be involved in the electrostatic interaction with CNGA1.The RA domain is highly conserved among the members of Grb7 family of proteins,which includes Grb7,Grb10 and Grb14.Further,only Grb14 is able to modulate the channel activity,but not Grb7 and Grb10.All together,it suggests the existence of a divergence in RA domains among the members of the Grb7 family.

Conservation and divergence of Grb7 family of Ras-binding domains

Ras proteins are signal-transducing GTPases that cycle between inactive GDP-bound and active GTP-bound forms.Ras is a prolific signaling molecule interacting with a spectrum of effector molecules and acting through more than one signaling pathway.The Ras-effector proteins contain a Ras-associating(RA)domain through which these associate with Ras in a GTP-dependent manner.The RA domain is highly conserved among the members of the growth factor receptor-bound(Grb)7 family of proteins which includes Grb7,Grb10 and Grb14.Our laboratory has reported an unusual observation that RA domain of Grb14 binds to the C-terminal nucleotide binding site of cyclic nucleotide gated channel(CTRCNGA1)and inhibits the channel activity.Molecular modeling of the CTR-CNGA1 displays 50%---70%tertiary structural similarity towards Ras proteins.We named this region as Ras-like domain(RLD).The interaction between RA-Grb14 and RLD-CNGA1 is mediated through a simple protein-protein interaction temporally and spatially regulated by light and cGMP.It is interesting to note that Grb14 binds to GTPase-mutant Rab5,a Ras-related small GTPase whereas Grb10 binds only to GTP-bound form of active Rab5 but not to GTPase-defective mutant Rab5.These results suggest that Grb14 might have been evolved later in the evolution that binds to both Ras and nucleotide binding proteins such as CNGA1.Our studies also suggest that eukaryotic CNG channels could be evolved through a gene fusion between prokaryotic ion channels and cyclic nucleotide binding proteins,both of which might have undergone several sequence variations for functional adaptation during evolution.