The macula densa site of avian kidney

Summary The macula densa (MD) site of the kidney, at which the distal tubule is attached to the vascular pole of the glomerulus, was examined with the light microscope in domestic fowl and Japanese quail; and in the fowl also with the electron microscope. The characteristics of mammalian MD cells, as reported in the literature, are compared with those of the cells in the avian MD site. The avian cells possess some of the characteristics of mammalian MD cells and they are distinguishable from the cells in adjacent portions of the distal tubule. The Golgi system in the avian cells is apical to the nucleus, unlike in mammals where its location is basal. The cells in the avian MD sites can be considered as structurally transitional between the typical MD cells in mammals and the ordinary cells of the distal tubule. These findings are discussed in relation to the function of the avian kidney and to its control by the renin mechanism.* This investigation was supported in part by U.S. Public Health Service Research Grant HE 10338 from the National Heart Institute. We thank Mr. T. Takizawa for technical assistance. A preliminary report of this study was given at the 13th Annual Meeting of Japanese Society of Nephrology in Kyoto, 1970.     

Dietary intake of the citrus flavonoid hesperidin affects stress-resilience and brain kynurenine levels in a subchronic and mild social defeat stress model in mice

ABSTRACT

Depressive disorders are partly caused by chronic inflammation through the kynurenine (KYN) pathway. Preventive intervention using anti-inflammatory reagents may be beneficial for alleviating the risk of depression. In this study, we focused on the Japanese local citrus plant, Citrus tumida hort. ex Tanaka (C. tumida; CT), which contains flavonoids such as hesperidin that have anti-inflammatory actions. The dietary intake of 5% immature peels of CT fruits slightly increased stress resilience in a subchronic and mild social defeat (sCSDS) model in mice. Moreover, the dietary intake of 0.1% hesperidin significantly increased stress resilience and suppressed KYN levels in the hippocampus and prefrontal cortex in these mice. In addition, KYN levels in the hippocampus and prefrontal cortex were significantly correlated with the susceptibility to stress. In conclusion, these results suggest that dietary hesperidin increases stress resilience by suppressing the augmentation of KYN signaling under sCSDS.     

Effects of carbohydrate substrate on the vegetative mycelial growth of an ectomycorrhizal mushroom, <Emphasis Type="Italic">Tricholoma matsutake</Emphasis>, isolated from <Emphasis Type="Italic">Quercus</Emphasis>

We studied the characteristics of the utilization of carbohydrate substrates and the production of those hydrolyzing enzymes of the Tricholoma matsutake J-1 strain isolated from hardwood (Quercus sp.). In the culture medium, 5% glucose inhibited mycelial growth. The growth inhibition rate was remarkable in the Z-1 strain from softwood (Pinus densiflora) compared with that of the J-1 strain from hardwood. α-Amylase production varied with starches from different origins in contrast to mycelial growth. The range of the effect of 0.5%–15% soluble starch on vegetative mycelial growth was also investigated. The optimal concentration for mycelial growth was 15% for the J-1 strain but 10% for the Z-1 strain. Mycelial growth of the J-1 strain was strongly inhibited in PMML medium containing Sunpeal-CP prepared from sulfite pulp softwood waste, but that of the Z-1 strain was not inhibited by Sunpeal-CP. Moreover, mycelial growth of the J-1 strain from Quercus sp. dramatically decreased with the addition of CNF-HWSF (hot water-soluble fractions from corn fiber) to the PMML and PDL medium. However, inhibition by CNF-HWSF was not shown in the Z-1 strain from P. densiflora.     

Abi-1-bridged tyrosine phosphorylation of VASP by Abelson kinase impairs association of VASP to focal adhesions and regulates leukaemic cell adhesion

Mena [mammalian Ena (Enabled)]/VASP (vasodilator-stimulated phosphoprotein) proteins are the homologues of Drosophila Ena. In Drosophila, Ena is a substrate of the tyrosine kinase DAbl (Drosophila Abl). However, the link between Abl and the Mena/VASP family is not fully understood in mammals. We previously reported that Abi-1 (Abl interactor 1) promotes phosphorylation of Mena and BCAP (B-cell adaptor for phosphoinositide 3-kinase) by bridging the interaction between c-Abl and the substrate. In the present study we have identified VASP, another member of the Mena/VASP family, as an Abi-1-bridged substrate of Abl. VASP is phosphorylated by Abl when Abi-1 is co-expressed. We also found that VASP interacted with Abi-1 both in vitro and in vivo. VASP was tyrosine-phosphorylated in Bcr-Abl-positive leukaemic cells in an Abi-1-dependent manner. Co-expression of c-Abl and Abi-1 or the phosphomimetic Y39D mutation in VASP resulted in less accumulation of VASP at focal adhesions. VASP Y39D had a reduced affinity to the proline-rich region of zyxin. Interestingly, overexpression of both phosphomimetic and unphosphorylated forms of VASP, but not wild-type VASP, impaired adhesion of K562 cells to fibronectin. These results suggest that the phosphorylation and dephosphorylation cycle of VASP by the Abi-1-bridged mechanism regulates association of VASP with focal adhesions, which may regulate adhesion of Bcr-Abl-transformed leukaemic cells.     

CCN3 controls 3D spatial localization of melanocytes in the human skin through DDR1

Melanocytes reside within the basal layer of the human epidermis, where they attach to the basement membrane and replicate at a rate proportionate to that of keratinocytes, maintaining a lifelong stable ratio. In this study, we report that coculturing melanocytes with keratinocytes up-regulated CCN3, a matricellular protein that we subsequently found to be critical for the spatial localization of melanocytes to the basement membrane. CCN3 knockdown cells were dissociated either upward to the suprabasal layers of the epidermis or downward into the dermis. The overexpression of CCN3 increased adhesion to collagen type IV, the major component of the basement membrane. As the receptor responsible for CCN3-mediated melanocyte localization, we identified discoidin domain receptor 1 (DDR1), a receptor tyrosine kinase that acts as a collagen IV adhesion receptor. DDR1 knockdown decreased melanocyte adhesion to collagen IV and shifted melanocyte localization in a manner similar to CCN3 knockdown. These results demonstrate an intricate and necessary communication between keratinocytes and melanocytes in maintaining normal epidermal homeostasis.     

MHC class I-like MILL molecules are beta2-microglobulin-associated, GPI-anchored glycoproteins that do not require TAP for cell surface expression

MILL (MHC class I-like located near the leukocyte receptor complex) is a family of MHC class I-like molecules encoded outside the MHC, which displays the highest sequence similarity to human MICA/B molecules among known class I molecules. In the present study, we show that the two members of the mouse MILL family, MILL1 and MILL2, are GPI-anchored glycoproteins associated with beta2-microglobulin (beta2m) and that cell surface expression of MILL1 or MILL2 does not require functional TAP molecules. MILL1 and MILL2 molecules expressed in bacteria could be refolded in the presence of beta2m, without adding any peptides. Hence, neither MILL1 nor MILL2 is likely to be involved in the presentation of peptides. Immunohistochemical analysis revealed that MILL1 is expressed in a subpopulation of thymic medullary epithelial cells and a restricted region of inner root sheaths in hair follicles. The present study provides additional evidence that MILL is a class I family distinct from MICA/B.     

Progressive renal dysfunction and macrophage infiltration in interstitial fibrosis in an adenine-induced tubulointerstitial nephritis mouse model

Adenine phosphoribosyltransferase deficiency in mice or an excessive oral intake of adenine leads to the accumulation of 2,8-dihydroxyadenine (DHA) in renal tubules and that causes progressive renal dysfunction accompanied by interstitial fibrosis. However, the precise mechanism responsible for DHA-induced progressive fibrosis is not fully understood. The present study investigates the possible involvement of monocytes/macrophages in the progressive fibrosis induced by feeding adenine to mice. Urinary calculi were deposited in tubules on day 7 after the initiation of adenine feeding. Elevation of the serum creatinine level and loss of body weight were observed in a time-dependent manner, suggesting the development of typical renal dysfunction induced by the adenine feeding. In renal tissue, mRNA expression of MCP-1, MIP-1α, RANTES, IL-1β, CCR2, TGF-β, α-smooth muscle actin (α-SMA) and collagen 1a1 was increased in parallel. Along with the increased expression of these genes, a remarkable infiltration of macrophages into the tubulointerstitial area was observed in a time-dependent manner. In addition, in the tubulointerstitial area, α-SMA positive fibroblasts were increased in parallel with collagen deposition. These results suggest that the excessive consumption of adenine leads to progressive renal dysfunction in mice. We speculate that the accumulation of DHA in tubules might stimulate epithelium to produce MCP-1 and that profibrogenic TGF-β produced by infiltrated macrophages might stimulate interstitial fibroblasts to produce collagen. These results indicate that macrophage infiltration is one of the triggers that initiates interstitial fibroblast activation and collagen deposition followed by renal dysfunction.     

Inhibition of human immunodeficiency virus type 1 (HIV-1) nuclear import via Vpr-Importin α interactions as a novel HIV-1 therapy

The development of multidrug-resistant viruses compromises the efficacy of anti-human immunodeficiency virus (HIV) therapy and limits treatment options. Therefore, new targets that can be used to develop novel antiviral agents need to be identified. One such target is the interaction between Vpr, one of the accessory gene products of HIV-1 and Importin α, which is crucial, not only for the nuclear import of Vpr, but also for HIV-1 replication in macrophages. We have identified a potential parent compound, hematoxylin, which suppresses Vpr-Importin α interaction, thereby inhibiting HIV-1 replication in a Vpr-dependent manner. Analysis by real-time PCR demonstrated that hematoxylin specifically inhibited nuclear import step of pre-integration complex. Thus, hematoxylin is a new anti-HIV-1 inhibitor that targets the nuclear import of HIV-1 via the Vpr-Importin α interaction, suggesting that a specific inhibitor of the interaction between viral protein and the cellular factor may provide a new strategy for HIV-1 therapy.     

Lupeol reduces triglyceride and cholesterol synthesis in human hepatoma cells

Lupeol suppressed triglyceride and cholesterol secretion from HepG2-Lipo human hepatoma cells in a dose-dependent manner. Quantitative real-time RT-PCR analysis demonstrated that lupeol inhibited the expressions of sterol regulatory element-binding protein-1c and -2, fatty acid synthase, 3-hydroxy-3-methylglutaryl-Coenzyme A synthetase-1, and farnesyl-diphosphate farnesyl transferase-1, which are required for lipid synthesis in HepG2-Lipo cells. Furthermore, lupeol markedly inhibited apolipoproteinB-100 and microsomal triglyceride transfer protein in cells at the mRNA level. These results suggest that lupeol lowers lipid secretion from HepG2-Lipo cells by attenuating synthesis within the cells.     

Inhibitory effects of coumarin and acetylene constituents from the roots of Angelica furcijuga on D-galactosamine/lipopolysaccharide-induced liver injury in mice and on nitric oxide production in lipopolysaccharide-activated mouse peritoneal macrophages

The methanolic extract (200 mg/kg, p.o. and i.p.), principal coumarin constituents (isoepoxypteryxin, anomalin, and praeroside IV), and a polyacetylene constituent (falcarindiol) (25 mg/kg, i.p.) from the roots of Angelica furcijuga protected the liver injury induced by D-galactosamine (D-GalN)/lipopolysaccharide (LPS) in mice. In in vitro experiments, coumarin constituents (hyuganins A-D, anomalin, pteryxin, isopteryxin, and suksdorfin) and polyacetylene constituents [(-)-falcarinol and falcarindiol] substantially inhibited LPS-induced NO and/or TNF-alpha production in mouse peritoneal macrophages, and isoepoxypteryxin inhibited D-GalN-induced cytotoxicity in primary cultured rat hepatocytes. Furthermore, hyuganin A, anomalin, and isopteryxin inhibited the decrease in cell viability by TNF-alpha in L929 cells.