The roles of integrin β4 in vascular endothelial cells

Integrin heterodimers play diverse and important roles in physiological and pathological processes, such as cell adhesion, migration, proliferation, differentiation, angiogenesis, and tumor progression, via the outside-in and/or inside-out signaling pathways. Aberrant functions of integrins have been implicated in the causation and intervention of multiple diseases. Integrin β(4), a laminin-5 (LN5) receptor, mainly locates in the adhesion structure of hemidesmosome (HD). Most of the previous researches concentrated on the role of integrin β(4) in cancer and cancer therapy, and a few focused on the physiological roles of normal mammalian cells. Recently, accumulating data reveal that integrin β(4) participates in cell death, macroautophagy (hereafter autophagy), senescence, and differentiation regulations in various cell types including human umbilical vein endothelial cells (HUVECs), mesenchymal stem cells, and mouse neural cells, implying the key roles of integrin β(4) in the physiological alteration of mammalian cells. Thus, the elucidation of integrin β(4)-mediated signaling may undoubtedly contribute to novel therapeutic strategies for various human diseases, such as vascular and neural disorders. We have reviewed the roles of integrin β(4) in neural cells. In the present review we will discuss the recent research progress in the inherent functions and pharmacological modulation of integrin β(4) in vascular endothelial cells.     

EPR analysis of multiple forms of [4Fe–4S]3+ clusters in HiPIPs

The electron paramagnetic resonance (EPR) spectrum from the [4Fe–4S]³⁺ cluster in several high-potential iron–sulfur proteins (HiPIPs) is complex: it is not the pattern of a single, isolated S=1/2 system. Multifrequency EPR from 9 to 130 GHz reveals that the apparent peak positions (g values) are frequency-independent: the spectrum is dominated by the Zeeman interaction plus g-strain broadening. The spectra taken at frequencies above the X-band are increasingly sensitive to rapid-passage effects; therefore, the X-band data, which are slightly additionally broadened by dipolar interaction, were used for quantitative spectral analysis. For a single geometrical [4Fe–4S]³⁺ structure the (Fe–Fe)⁵⁺ mixed-valence dimer can be assigned in six different ways to a pair of iron ions, and this defines six valence isomers. Systematic multicomponent g-strain simulation shows that the [4Fe–4S]³⁺ paramagnets in seven HiPIPs from different bacteria each consist of three to four discernible species, and these are assigned to valence isomers of the clusters. This interpretation builds on previous EPR analyzes of [4Fe–4S]³⁺ model compounds, and it constitutes a high-resolution extension of the current literature model, proposed from paramagnetic NMR studies.     

The role of hepatic Surf4 in lipoprotein metabolism and the development of atherosclerosis in apoE−/− mice

Elevated plasma levels of low-density lipoprotein-C (LDL-C) increase the risk of atherosclerotic cardiovascular disease. Circulating LDL is derived from very low-density lipoprotein (VLDL) metabolism and cleared by LDL receptor (LDLR). We have previously demonstrated that cargo receptor Surfeit 4 (Surf4) mediates VLDL secretion. Inhibition of hepatic Surf4 impairs VLDL secretion, significantly reduces plasma LDL-C levels, and markedly mitigates the development of atherosclerosis in LDLR knockout (Ldlr^?/?) mice. Here, we investigated the role of Surf4 in lipoprotein metabolism and the development of atherosclerosis in another commonly used mouse model of atherosclerosis, apolipoprotein E knockout (apoE^?/?) mice. Adeno-associated viral shRNA was used to silence Surf4 expression mainly in the liver of apoE^?/? mice. In apoE^?/? mice fed a regular chow diet, knockdown of Surf4 expression significantly reduced triglyceride secretion and plasma levels of non-HDL cholesterol and triglycerides without causing hepatic lipid accumulation or liver damage. When Surf4 was knocked down in apoE^?/? mice fed the Western-type diet, we observed a significant reduction in plasma levels of non-HDL cholesterol, but not triglycerides. Knockdown of Surf4 did not increase hepatic cholesterol and triglyceride levels or cause liver damage, but significantly diminished atherosclerosis lesions. Therefore, our findings indicate the potential of hepatic Surf4 inhibition as a novel therapeutic strategy to reduce the risk of atherosclerotic cardiovascular disease.     

Role of PPARα and HNF4α in Stress-Mediated Alterations in Lipid Homeostasis

Stress is a risk factor for several cardiovascular pathologies. PPARα holds a fundamental role in control of lipid homeostasis by directly regulating genes involved in fatty acid transport and oxidation. Importantly, PPARα agonists are effective in raising HDL-cholesterol and lowering triglycerides, properties that reduce the risk for cardiovascular diseases. This study investigated the role of stress and adrenergic receptor (AR)-related pathways in PPARα and HNF4α regulation and signaling in mice following repeated restraint stress or treatment with AR-antagonists administered prior to stress to block AR-linked pathways. Repeated restraint stress up-regulated Pparα and its target genes in the liver, including Acox, Acot1, Acot4, Cyp4a10, Cyp4a14 and Lipin2, an effect that was highly correlated with Hnf4α. In vitro studies using primary hepatocyte cultures treated with epinephrine or AR-agonists confirmed that hepatic AR/cAMP/PKA/CREB- and JNK-linked pathways are involved in PPARα and HNF4α regulation. Notably, restraint stress, independent of PPARα, suppressed plasma triglyceride levels. This stress-induced effect could be attributed in part to hormone sensitive lipase activation in the white adipose tissue, which was not prevented by the increased levels of perilipin. Overall, this study identifies a mechanistic basis for the modification of lipid homeostasis following stress and potentially indicates novel roles for PPARα and HNF4α in stress-induced lipid metabolism.     

Effect of PLCβ4 in the thalamus on the EEG in REM sleep

Sleep and Biological Rhythms -     

Evaluation of Antiinflammatory Activity of 4'-О-Methylhonokiol Derivatives in a Neuroinflammation Model

Russian Journal of Bioorganic Chemistry - The synthesis of two derivatives of lignan 4'-O-methylhonokiol (MH), i.e., 4'-methoxy-5-propyl-1,1'-biphenyl-2-ol (III) and...     

Characterization of the Testis-specific Proteasome Subunit α4s in Mammals

The 26 S proteasome is responsible for regulated proteolysis in eukaryotic cells. It is composed of one 20 S core particle (CP) flanked by one or two 19 S regulatory particles. The CP is composed of seven different α-type subunits (α1-α7) and seven different β-type subunits, three of which are catalytic. Vertebrates encode four additional catalytic β subunits that are expressed predominantly in immune tissues and produce distinct subtypes of CPs particularly well suited for the acquired immune system. In contrast, the diversity of α subunits remains poorly understood. Recently, another α subunit, referred to as α4s, was reported. However, little is known about α4s. Here we provide a detailed characterization of α4s and the α4s-containing CP. α4s is exclusively expressed in germ cells that enter the meiotic prophase and is incorporated into the CP in place of α4. A comparison of structural models revealed that the differences in the primary sequences between α4 and α4s are located on the outer surface of the CP, suggesting that α4s interacts with specific molecules via these unique regions. α4s-containing CPs account for the majority of the CPs in mouse sperm. The catalytic β subunits in the α4s-containing CP are β1, β2, and β5, and immunosubunits are not included in the α4s-containing CP. α4s-containing CPs have a set of peptidase activities almost identical to those of α4-containing CPs. Our results provide a basis for understanding the role of α4s and male germ cell-specific proteasomes in mammals.     

Metabolism of 4-pyridone-3-carboxamide-1-??-d-ribonucleoside (4PYR) in rodent tissues and in vivo

Our previous studies identified 4-pyridone-3-carboxamide-1-β-D-ribonucleoside (4PYR) phosphates in human erythrocytes. We demonstrated formation of these nucleotides by phosphorylation of 4PYR and potential toxicity due to disruption of erythrocyte energy balance. This study aimed to evaluate the ability of the other cell types to phosphorylate 4PYR to characterize function and toxicity of these compounds. Homogenates of rat heart, kidneys, and liver were used to study the rate of 4PYR phosphorylation in the presence of ATP. In another experiment, 4PYR was administered into mouse as repeated subcutaneous injections and into rats as intraperitoneal infusion. After 7 days, heart, liver, kidney, lungs, and skeletal muscle were collected, and the concentration of 4PYR nucleotides was evaluated. HPLC was used to measure 4PYR and 4PYR nucleotides in homogenate and specimens from in vivo experiments. 4PYR was rapidly phosphorylated by the liver homogenate (390 ± 27 nmol/min/g wet wt). Significant rates were reported in the heart and kidneys' homogenates: 34.3 ± 4.3 nmol/min/g and 33.2 ± 9.2 nmol/min/g, respectively. Phosphorylation of 4PYR was almost completely inhibited by adenosine kinase inhibitor 5'-iodotubercidin. Administration of 4PYR in vivo resulted in accumulation of 4PYR monophosphate in the liver, heart, skeletal muscle, and lung (20-220 nmol/g dry wt) except kidney (<1 nmol/g). In contrast to erythrocytes, no 4PYR triphosphate formation (<1 nmol/g) was observed in any of the organs studied. We conclude that not only the erythrocytes but also other cell types are capable of phosphorylating 4PYR to form 4PYR monophosphate. Potential toxicity or physiological role of 4PYR in peripheral organs could be considered, but mechanisms will be different from that in erythrocytes.     

The role of interferon γ in regulation of CD4 T-cells and its clinical implications

Interferon γ (IFNγ) plays a central role in the immune response against infection and tumur immune surveillance. Its functions include not only activation of the host immune system to control microbial infections but also repression of autoimmune responses by turning on T-regulatory cells and increasing T effector cell apoptosis. Defects in IFNγ and IFNγ receptor genes have been associated with autoimmune diseases such as rheumatoid arthritis, type 1 diabetes and multiple sclerosis. However, treatment of autoimmune diseases by supplementing with IFNγ has been satisfactory due to its broad biological effects. Instead, its target T-regulatory cells may be used for the clinical treatment of autoimmune diseases. Future study could also focus on promotion of the beneficial effects of IFNγ and blocking those unwanted IFNγ-induced activities.     

Identification of Gy4 nulls and development of multiplex PCR-based co-dominant marker for Gy4 and α’ subunit of β-conglycinin in soybean

Alpha prime (α’) subunit of β-conglycinin and Gy4 subunit of glycinin are two important subunits of soybean storage protein which have negative effects on food processing, total amino acid content, and hypersensitivity reactions. It has been possible to reduce or remove some of these problems from soybean by screening or developing mutant lines. The objective of this study was to establish a simple, cheap DNA marker for Gy4 and α’ subunit for use in non-seed destructive, marker-assisted selection (MAS) that can identify these two mutants at the same time in a unique PCR reaction. To achieve this objective, we identified eight of Gy4 mutants from diverse soybean accessions from the USDA Soybean Germplasm Collection and described a multiplex PCR based co-dominant DNA marker for Gy4 subunit of glycinin. Then we crossed one of these Gy4 mutants with Keburi (α’ mutant) for development of double mutant variety and established a multiplex PCR based, co-dominant DNA marker for screening Gy4 and α’ mutants. Thus, using this newly developed marker to identify Gy4 and α’ mutants in breeding programs we could save our time, labor, and resources.     

Nuclear-cytoplasmic interactions in restoration of male fertility in the ‘9E’ and A4 CMS-inducing cytoplasms of sorghum

 The genetics of male-fertility restoration in sorghum in the “9E” and A4 CMS-inducing cytoplasms, was studied by crossing a number of fertility restorer lines of A1 cytoplasm to CMS lines [9E]T×398 and [A4]T×398 and the line [9E]Milo-10, which was obtained by backcrossing Milo-10 to [9E]T×398. It was revealed that both A4 and “9E” cytoplasms are characterized by a sporophytic mode of restoration of male fertility. Depending on the nuclear background of the male parents, fertility restoration was controlled by one or two dominant genes. Fertility-restorer genes of one of the tester lines, KVV-114, were effective in [9E]T×398 but could not restore [9E]Milo-10. A fertile line obtained from the fertile hybrid [9E]T×398/KVV-112, with “9E” cytoplasm, also failed to restore [9E]Milo-10. In a number of hybrid combinations with both A4 and “9E” cytoplasms a novel and unusual phenomenon of gradual restoration of male fertility in subsequent backcross generations was observed. Pollen from the fertile revertants did not transmit fertility restoration in progeny from crosses with the original CMS line and was poorly transmitted in sib-crosses. The appearance of fertile revertants and the different reactions of different CMS lines with the same cytoplasm in test-crosses may be caused by the action of recessive nuclear genes of the recurrent male parents that were accumulated during backcrossing; these may induce changes in cytoplasmic genes controlling CMS. Received: 5 March 1998 / Accepted: 7 April 1998     

The mode of action of 4-methylumbelliferyl β-d-xyloside on the synthesis of chondroitin sulphate in embryonic-chicken sternum

1. Embryonic-chicken sterna, incubated in medium containing 0.1mm-4-methylumbelliferyl beta-d-xyloside (4-methylcoumarin 7-beta-d-xyloside), synthesize proteochondroitin sulphate that is significantly undersulphated and shorter than usual [Gibson, Segen & Audhya (1977) Biochem. J.162, 217-233]. 2. Neither the beta-d-galactoside nor the beta-d-glucuronide of 4-methylumbelliferone, nor 4-methylumbelliferone itself, produced the effects. The only metabolites of 4-methylumbelliferone that were detected in cartilages exposed to 4-methylumbelliferyl beta-d-xyloside were unchanged xyloside and chondroitin sulphate covalently attached to 4-methylumbelliferone. 3. Gel filtration of salt extracts of sterna incubated in medium containing the xyloside showed that there were two pools of chondroitin sulphate in the tissue. One pool was identified, on the basis of its elution pattern and the linear kinetics of incorporation of sulphate into it, as proteochondroitin sulphate. Incorporation into the other pool, whose properties suggested that it was methylumbelliferyl-chondroitin sulphate, indicated that it underwent partial turnover. The molecular weight of this chondroitin sulphate was about 19000, and it appeared to be about 70% sulphated. 4. When sterna were incubated in medium containing the xyloside, there was a very large incorporation of sulphate and glucose into glycosaminoglycans that were released into the incubation medium. This contrasts with incubations of sterna in the absence of the xyloside, in which less than 5% of the sulphate incorporated could be recovered from the medium. The glycosaminoglycan released into the medium was 4-methylumbelliferyl-chondroitin sulphate, whose average molecular weight was 7000-8000 and degree of sulphation more than 95%. 5. Incorporation of sulphate into proteochondroitin sulphate was stimulated more than 3-fold by addition of 20% (v/v) human serum and 10nm-l-3,3',5-tri-iodothyronine. Incorporation into methylumbelliferyl-chondroitin sulphate, in either the tissue or the medium, was not significantly altered. 6. The decrease in chain length and degree of sulphation of proteochondroitin sulphate is explained in terms of competition between peptide-linked primers and methylumbelliferone-containing primers at the intracellular sites of polysaccharidechain elongation and sulphation. The implications of the results for the mechanism of stimulation of proteoglycan synthesis by serum factors are discussed.     

Multiple elements in the eIF4G1 N-terminus promote assembly of eIF4G1•PABP mRNPs in vivo

eIF4G is the scaffold subunit of the eIF4F complex, whose binding domains for eIF4E and poly(A)-binding protein (PABP) are thought to enhance formation of activated eIF4F•mRNA•PABP complexes competent to recruit 43S pre-initiation complexes. We found that the RNA-binding region (RNA1) in the N-terminal domain (NTD) of yeast eIF4G1 can functionally substitute for the PABP-binding segment to rescue the function of an eIF4G1-459 mutant impaired for eIF4E binding. Assaying RNA-dependent PABP–eIF4G association in cell extracts suggests that RNA1, the PABP-binding domain, and two conserved elements (Box1 and Box2) between these segments have overlapping functions in forming native eIF4G•mRNA•PABP complexes. In vitro experiments confirm the role of RNA1 in stabilizing eIF4G–mRNA association, and further indicate that RNA1 and Box1 promote PABP binding, in addition to RNA binding, by the eIF4G1 NTD. Our findings indicate that PABP–eIF4G association is only one of several interactions that stabilize eIF4F•mRNA complexes, and emphasize that closed-loop mRNP formation via PABP–eIF4G interaction is non-essential in vivo. Interestingly, two other RNA-binding regions in eIF4G1 have critical functions downstream of eIF4F•mRNA assembly.     

Tissue distribution and age-dependent expression ofβ-4-N-acetylgalactosaminyltransferase in guinea-pig

Guinea-pig kidney contains -4-N-acetylgalactosaminyltransferase which may be involved in the biosynthesis of the Sd a determinant expressed on Tamm-Horsfall glycoprotein. In the present study we show that this enzyme is expressed far more in the medulla than in the cortex of the kidney and that, among the other organs tested, is expressed only in colon and caecum. This transferase is ontogenically regulated, in that its activity is low at birth and increases as a function of age. From several aspects, the tissue distribution and the ontogenic expression of -4-N-acetylgalactosaminyl-transferase and Tamm-Horsfall glycoprotein are similar.