Deficiency of Macf1 in osterix expressing cells decreases bone formation by Bmp2/Smad/Runx2 pathway

Microtubule actin cross‐linking factor 1 (Macf1) is a spectraplakin family member known to regulate cytoskeletal dynamics, cell migration, neuronal growth and cell signal transduction. We previously demonstrated that knockdown of Macf1 inhibited the differentiation of MC3T3‐E1 cell line. However, whether Macf1 could regulate bone formation in vivo is unclear. To study the function and mechanism of Macf1 in bone formation and osteogenic differentiation, we established osteoblast‐specific Osterix (Osx) promoter‐driven Macf1 conditional knockout mice (Macf1^f/fOsx‐Cre). The Macf1^f/fOsx‐Cre mice displayed delayed ossification and decreased bone mass. Morphological and mechanical studies showed deteriorated trabecular microarchitecture and impaired biomechanical strength of femur in Macf1^f/fOsx‐Cre mice. In addition, the differentiation of primary osteoblasts isolated from calvaria was inhibited in Macf1^f/fOsx‐Cre mice. Deficiency of Macf1 in primary osteoblasts inhibited the expression of osteogenic marker genes (Col1, Runx2 and Alp) and the number of mineralized nodules. Furthermore, deficiency of Macf1 attenuated Bmp2/Smad/Runx2 signalling in primary osteoblasts of Macf1^f/fOsx‐Cre mice. Together, these results indicated that Macf1 plays a significant role in bone formation and osteoblast differentiation by regulating Bmp2/Smad/Runx2 pathway, suggesting that Macf1 might be a therapeutic target for bone disease.     

Overexpressions of cDNAs for β-Amyloid Precursor Proteins 695, 751, and 770 Enhance the Secretion of β-Amyloid Precursor Protein Derivatives and the Survival of P19-Derived Neurons

Abstract: P19 is a C3H mouse-derived line of multipotent embryonic carcinoma cells that differentiate into neural cells. P19 cell clones overexpressing the three major forms of β-amyloid precursor protein from their cDNA constructs were established. Unlike a previous study in which P19-derived neurons had a limited α-secretase activity, all of these clones produced significant amounts of secreted β-amyloid precursor protein. When treated with retinoic acid, these transformed lines differentiated into neurons and survived better than did nontransformed parental P19 cells. Furthermore, P19-derived neurons survived better in medium conditioned by the transformed P19 line, and survival was reduced by immunoabsorption with an antibody to β-amyloid precursor protein. These results suggest neurotrophic effects of secreted β-amyloid precursor protein and contrast with a previous report in which overexpression of a full-length cDNA for β-amyloid precursor protein led to degeneration of P19-derived neurons. Western blot analysis suggested that this difference might result from different levels of expression of putative neurotoxic C-terminal fragments of β-amyloid precursor protein; moreover, P19-derived neurons differ from P19 stem cells in the processing of these C-terminal fragments.     

A Lipidomic Approach to the Study of Biodiversity of Symbiotic Dinoflagellates in Millepora Hydrocorals from Vietnam Coral Reefs

Russian Journal of Marine Biology - To assess the biodiversity of symbiotic dinoflagellates (SD) in hydrocorals, we compared the molecular species compositions of four SD lipid classes such as...     

Transactivation of Atg4b by C/EBPβ Promotes Autophagy To Facilitate Adipogenesis

Autophagy is a highly conserved self-digestion pathway involved in various physiological and pathophysiological processes. Recent studies have implicated a pivotal role of autophagy in adipocyte differentiation, but the molecular mechanism for its role and how it is regulated during this process are not clear. Here, we show that CCAAT /enhancer-binding protein β (C/EBPβ), an important adipogenic factor, is required for the activation of autophagy during 3T3-L1 adipocyte differentiation. An autophagy-related gene, Atg4b, is identified as a de novo target gene of C/EBPβ and is shown to play an important role in 3T3-L1 adipocyte differentiation. Furthermore, autophagy is required for the degradation of Klf2 and Klf3, two negative regulators of adipocyte differentiation, which is mediated by the adaptor protein p62/SQSTM1. Importantly, the regulation of autophagy by C/EBPβ and the role of autophagy in Klf2/3 degradation and in adipogenesis are further confirmed in mouse models. Our data describe a novel function of C/EBPβ in regulating autophagy and reveal the mechanism of autophagy during adipocyte differentiation. These new insights into the molecular mechanism of adipose tissue development provide a functional pathway with therapeutic potential against obesity and its related metabolic disorders.     

The transsulfuration pathway in Tetrahymena pyriformis.

Four enzymes necessary for the metabolism of methionine by the trans-sulfuration pathway, methionine adenosyltransferase (EC 2.5.1.6), adenosylhomocysteinase (EC 3.3.1.1), cystathionine beta-synthase (EC 4.2.1.22) and cystathionine gamma-lyase (EC 4.4.1.1) were identified in Tetrahymean pyriformis. The ability of these cells to transfer 35S from E135S]methionine to form [35S] cysteine was also observed and taken as direct evidence for the functional existence of this pathway in Tetrahymena. An intermediate in the pathway and an active methyl donor, S-adenosylmethionine, was qualitatively identified in Tetrahymena and its concentration was found to be greater in late stationary phase cells than in early stationary phase cells.     

Interaction of dietary fat types and sesamin on hepatic fatty acid oxidation in rats

The interaction of sesamin, one of the most abundant lignans in sesame seed, and types of dietary fats affecting hepatic fatty acid oxidation was examined in rats. Rats were fed purified experimental diets supplemented with 0% or 0.2% sesamin (1:1 mixture of sesamin and episesamin), and containing 8% of either palm, safflower or fish oil for 15 days. Among the groups fed sesamin-free diets, the activity of various fatty acid oxidation enzymes was higher in rats fed fish oil than in those fed palm and safflower oils. Dietary sesamin increased enzyme activities in all groups of rats given different fats. The extent of the increase depended on dietary fat type, and a diet containing sesamin and fish oil in combination appeared to increase many of these parameters synergistically. In particular, the peroxisomal palmitoyl-CoA oxidation rate and acyl-CoA oxidase activity levels were much higher in rats fed sesamin and fish oil in combination than in animals fed sesamin and palm or safflower oil in combination. Analyses of mRNA levels revealed that a diet containing sesamin and fish oil increased the gene expression of various peroxisomal fatty acid oxidation enzymes and PEX11alpha, a peroxisomal membrane protein, in a synergistic manner while it increased the gene expression of mitochondrial fatty acid oxidation enzymes and microsomal cytochrome P-450 IV A1 in an additive manner. It was concluded that a diet containing sesamin and fish oil in combination synergistically increased hepatic fatty acid oxidation primarily through up-regulation of the gene expression of peroxisomal fatty acid oxidation enzymes.     

Syntheses, crystal structures, and magnetic properties of Ni(mnt)2-based molecular solids containing substituted isoquinolinium

Two novel ion-pair complexes, [RBzIQl]⁺[Ni(mnt)₂]⁻ (mnt²⁻ = maleonitriledithiolate, [RBzIQl]⁺ = 4-R-benzylisoquinolinium; R = H (1), Cl (2)) have been characterized structurally and magnetically. The anions and [BzIQl]⁺ cations of 1 form 1D column of alternating between cations and anions via π?π stacking interaction between Ni(mnt)₂ plane and isoquinoline ring, and the Ni(mnt)₂ anions between adjacent columns exist C?N, C?N, and N?N interaction. The anions and cations of 2 stack into well-segregated columns in the solid state; and the Ni(III) ions form a 1D zigzag chain in a Ni(mnt)₂ column through intermolecular Ni?S, S?S, Ni?Ni or π?π interactions. The chain is uniform in 2 with the Ni?Ni distances of 3.784 Å. Magnetic susceptibility measurements for these complexes in the temperature range 1.8-300 K show that 1 exhibits antiferromagnetic coupling behavior, and 2 exhibits unusual magnetic phase transitions around 45 K. The overall magnetic behavior for 2 indicates the presence of antiferromagnetic interaction in the high-temperature phase (HT) and spin gap in the low-temperature phase (LT).     

Infrequent detection of KI, WU and MC polyomaviruses in immunosuppressed individuals with or without progressive multifocal leukoencephalopathy

Conflicting prevalence of newly identified KI (KIPyV), WU (WUPyV) and Merkel Cell Carcinoma (MCPyV) polyomaviruses have been reported in progressive multifocal leukoencephalopathy (PML) patient samples, ranging from 0 to 14.3%. We analyzed the prevalence of these polyomaviruses in cerebrospinal fluid (CSF), peripheral blood mononuclear cells (PBMC), and bone marrow samples from PML patients, immunosuppressed individuals with or without HIV, and multiple sclerosis (MS) patients. Distinct PCR tests for KIPyV, WUPyV and MCPyV DNA performed in two independent laboratories detected low levels of MCPyV DNA only in 1/269 samples. The infrequent detections of these viruses in multiple samples from immunosuppressed individuals including those with PML suggest that their reactivation mechanisms may be different from that of JC polyomavirus (JCPyV) and that they do not play a role in the pathogenesis of PML.     

Substituted aminobenzimidazole pyrimidines as cyclin-dependent kinase inhibitors

A series of aminobenzimidazole-substituted pyrimidines were synthesized and evaluated for biochemical activity against CDK1. A high-speed parallel synthesis approach enabled the identification of a potent lead series having improved potency in the CDK1 assay (IC(50)<10nM). Cell cycle analysis showed that the compounds induced a G2/M block. Docking studies were carried out with a CDK1 homology model, and provide a rationale for the observed activities.