Phosphodiesterases (PDEs) are a superfamily of enzymes that degrade the intracellular second messengers cyclic AMP and cyclic GMP. As essential regulators of cyclic nucleotide signalling with diverse physiological functions, PDEs are drug targets for the treatment of various diseases, including heart failure, depression, asthma, inflammation and erectile dysfunction. Of the 12 PDE gene families, cGMP-specific PDE5 carries out the principal cGMP-hydrolysing activity in human corpus cavernosum tissue. It is well known as the target of sildenafil citrate (Viagra) and other similar drugs for the treatment of erectile dysfunction. Despite the pressing need to develop selective PDE inhibitors as therapeutic drugs, only the cAMP-specific PDE4 structures are currently available. Here we present the three-dimensional structures of the catalytic domain (residues 537-860) of human PDE5 complexed with the three drug molecules sildenafil, tadalafil (Cialis) and vardenafil (Levitra). These structures will provide opportunities to design potent and selective PDE inhibitors with improved pharmacological profiles.

A series of small compounds acting at the orphan G proteincoupled receptor GPR92 were screened using a signaling pathway-specific reporter assay system. Lipid-derived molecules including farnesyl pyrophosphate (FPP), N-arachidonylglycine (NAG), and lysophosphatidic acid were found to activate GPR92. FPP and lysophosphatidic acid were able to activate both G q/11 -and G s -mediated signaling pathways, whereas NAG activated only the G q/11 -mediated signaling pathway. Computer-simulated modeling combined with site-directed mutagenesis of GPR92 indicated that Thr 97 , Gly 98 , Phe 101 , and Arg 267 of GPR92 are responsible for the interaction of GPR92 with FPP and NAG. Reverse transcription-PCR analysis revealed that GPR92 mRNA is highly expressed in the dorsal root ganglia (DRG) but faint in other brain regions. Peripheral tissues including, spleen, stomach, small intestine, and kidney also expressed GPR92 mRNA. Immunohistochemical analysis revealed that GPR92 is largely co-localized with TRPV1, a nonspecific cation channel that responds to noxious heat, in mouse and human DRG. FPP and NAG increased intracellular Ca 2؉ levels in cultured DRG neurons. These results suggest that FPP and NAG play a role in the sensory nervous system through activation of GPR92.

Recently, the incidence and prevalence of obesity and dyslipidemia are increasing. Dyslipidemia is associated with significant comorbidities and complications, and with cardiovascular risk factors (obesity, diabetes mellitus, hypertension and smoking). The main objectives of this article are that describe the prevalence of dyslipidemia in Korean children and adolescents and review the diagnosis and management of dyslipidemia in children and adolescents.

Obesity and older age are associated with development of NASH. Type 2 NASH is the most common form and associated with a greater severity of obesity and advanced fibrosis.

No abstract

Hypoxia-induced gene expression is initiated when the hypoxia-inducible factor-1 (HIF-1) alpha subunit is stabilized in response to a lack of oxygen. An HIF-1alpha-specific prolyl-hydroxylase (PHD) catalyzes hydroxylation of the proline-564 and/or -402 residues of HIF-1alpha by an oxygen molecule. The hydroxyproline then interacts with the ubiquitin E3 ligase von Hippel Lindau protein and is degraded by an ubiquitin-dependent proteasome. PHD2 is the most active of three PHD isoforms in hydroxylating HIF-1alpha. Structural analysis showed that the N-terminal region of PHD2 contains a Myeloid translocation protein 8, Nervy, and DEAF1 (MYND)-type zinc finger domain, whereas the catalytic domain is located in its C-terminal region. We found that deletion of the MYND domain increased the activity of both recombinant PHD2 protein and in vitro-translated PHD2. The zinc chelator N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine augmented the activity of wild-type PHD2-F but not that of PHD2 lacking the MYND domain, confirming that the zinc finger domain is inhibitory. Overexpression of PHD2 lacking the MYND domain caused a greater reduction in the stability and function of HIF-1alpha than did overexpression of wild-type PHD2, indicating that the MYND domain also inhibits the catalytic activity of PHD2 in vivo.

Chromatin Assembly Complex 1 (CAF-1) is a major histone chaperone involved in deposition of histone H3 and H4 into nucleosome. CAF-1 is composed of three subunits; p150, p60 and p48 for human and Cac1, Cac2 and Cac3 for yeast. Despite of its central role in chromatin formation, structural features of the full CAF-1 in complex with histones and other chaperones have not been well characterized. Here, we dissect molecular architecture of yeast CAF-1 (yCAF-1) by cross-linking mass spectrometry (XL-MS) and negative stain single-particle electron microscopy (EM). Our work revealed that Cac1, the largest subunit of yCAF-1, might serve as a major histone binding platform linking Cac2 and Cac3. In addition, EM analysis showed that yCAF-1 adopts a bilobal shape and Cac1 connecting Cac2 and Cac3 to generate a platform for binding histones. This study provides the first structural glimpse of the full CAF-1 complex and a structural framework to understand histone chaperoning processes.

Kap123, a major karyopherin protein of budding yeast, recognizes the nuclear localization signals (NLSs) of cytoplasmic histones H3 and H4 and translocates them into the nucleus during DNA replication. Mechanistic questions include H3- and H4-NLS redundancy toward Kap123 and the role of the conserved diacetylation of cytoplasmic H4 (K5ac and K12ac) in Kap123-mediated histone nuclear translocation. Here, we report crystal structures of full-length Kluyveromyces lactis Kap123 alone and in complex with H3- and H4-NLSs. Structures reveal the unique feature of Kap123 that possesses two discrete lysine-binding pockets for NLS recognition. Structural comparison illustrates that H3- and H4-NLSs share at least one of two lysine-binding pockets, suggesting that H3- and H4-NLSs are mutually exclusive. Additionally, acetylation of key lysine residues at NLS, particularly H4-NLS diacetylation, weakens the interaction with Kap123. These data support that cytoplasmic histone H4 diacetylation weakens the Kap123-H4-NLS interaction thereby facilitating histone Kap123-H3-dependent H3:H4/Asf1 complex nuclear translocation.