Comparative secretome analysis of human bone marrow‐derived mesenchymal stem cells during osteogenesis

Osteogenesis is a tightly regulated process that involves coordinated extracellular signals from autocrine and paracrine loops. Secretory proteins during osteogenesis can inhibit cell proliferation and activate cell differentiation toward mature osteoblasts, which are characterized by mineralization. In this study, we attempted to identify these secretory proteins during osteogenesis using LC–MS/MS analysis. We compared the secretome between undifferentiated human bone marrow‐derived mesenchymal stem cells (hBMSCs) and differentiated osteoblasts. Among 315 proteins that were identified, 177 proteins were present at increased levels in osteoblasts, whereas 88 proteins were present at decreased levels. Among the identified proteins, several were validated by quantitative RT‐PCR and immunoblot analysis. Of particular interest, calcium homeostasis‐related proteins were upregulated, whereas stem cell proliferation‐related proteins and other lineage‐related proteins were downregulated during osteogenesis. These findings provide information about the dynamic changes in the expression and secretion of proteins during osteogenesis and suggest the putative role of secretory proteins in osteogenesis. J. Cell. Physiol. 228: 216–224, 2013. © 2012 Wiley Periodicals, Inc.     

Daily activities and sleep quality in college students

There is growing evidence that social rhythms (e.g., daily activities such as getting into or out of bed, eating, and adhering to a work schedule) have important implications for sleep. The present study used a prospective measure of daily activities to assess the relation between sleep and social rhythms. College students (n=243) 18 to 39 yrs of age, completed the Social Rhythm Metric (SRM) each day for 14 d and then completed the Pittsburgh Sleep Quality Index (PSQI). The sample was divided into groups of good or poor sleepers, according to a PSQI cut‐off score of 5 points and was compared on the regularity, frequency, timing, and extent of social engagement during activities. There was a lower frequency and less regularity of social rhythms in poor sleepers relative to good sleepers. Good sleepers engaged more regularly in activities with active social engagement. Earlier rise time, first consumption of a beverage, going outdoors for the first time, and bedtime were associated with better sleep. Greater variability in rise time, consuming a morning beverage, returning home for the last time, and bedtime were associated with more disturbed sleep. The results are consistent with previous findings of reduced regularity in bedtime and rise time schedules in undergraduates, other age groups, and in clinical populations. Results augment the current thought that regulating behavioral zeitgebers may be important in influencing bed and rise times, and suggest that engaging in activities with other people may increase regularity.     

A Stopped-Flow Method for the Determination of Ascorbic Acid in Orange Juice Containing Triose Reductone

The adsorption of uranium by chitin phosphate and chitosan phosphate was investigated to obtain information on uranium recovery from aqueous systems, especially sea water and uranium mine waste water. The adsorption of uranium by chitin phosphate and chitosan phosphate was much greater than copper, cadmium, manganese, zinc, cobalt, nickel, magnesium and calcium. The adsorption of uranium was very rapid during the first 10 min and was affected by pH of the solution, temperature, granule radius and the co-existence of carbonate ion. The amounts of uranium adsorbed on the adsorbents increased linearly as the external uranium concentration increased. Uranium adsorbed on chitin phosphate easily desorbed with diluted sodium carbonate solution. On the other hand, uranyl and cobalt ions were separated from each other by using chitin phosphate.     

Biosynthesis and antimicrobial evaluation of backbone-cyclized α-defensins

Defensins are antimicrobial peptides that are important in the innate immune defense of mammals. Upon stimulation by bacterial antigens, enteric α-defensins are secreted into the intestinal lumen where they have potent microbicidal activities. Cryptdin-4 (Crp4) is an α-defensin expressed in Paneth cells of the mouse small intestine and the most bactericidal of the known cryptdin isoforms. The structure of Crp4 consists of a triple-stranded antiparallel β-sheet but lacks three amino acids between the fourth and fifth cysteine residues, making them distinct from other α-defensins. The structure also reveals that the α-amino and C-terminal carboxylic groups are in the proximity of each other (d ≈ 3 ?) in the folded structure. We present here the biosynthesis of backbone-cyclized Crp4 using a modified protein splicing unit or intein. Our data show that cyclized Crp4 can be biosynthesized by using this approach both in vitro and in vivo, although the expression yield was significantly lower when the protein was produced inside the cell. The resulting cyclic defensins retained the native α-defensin fold and showed equivalent or better microbicidal activities against several Gram-positive and Gram-negative bacteria when compared to native Crp4. No detectable hemolytic activity against human red blood cells was observed for either native Crp4 or its cyclized variants. Moreover, both forms of Crp4 also showed high stability to degradation when incubated with human serum. Altogether, these results indicate the potential for backbone-cyclized defensins in the development of novel peptide-based antimicrobial compounds.     

Fat/Hippo pathway regulates the progress of neural differentiation signaling in the Drosophila optic lobe

A large number of neural and glial cell species differentiate from neuronal precursor cells during nervous system development. Two types of Drosophila optic lobe neurons, lamina and medulla neurons, are derived from the neuroepithelial (NE) cells of the outer optic anlagen. During larval development, epidermal growth factor receptor (EGFR)/Ras signaling sweeps the NE field from the medial edge and drives medulla neuroblast (NB) formation. This signal drives the transient expression of a proneural gene, lethal of scute, and we refer to its signal array as the "proneural wave," as it is the marker of the EGFR/Ras signaling front. In this study, we show that the atypical cadherin Fat and the downstream Hippo pathways regulate the transduction of EGFR/Ras signaling along the NE field and, thus, ensure the progress of NB differentiation. Fat/Hippo pathway mutation also disrupts the pattern formation of the medulla structure, which is associated with the regulation of neurogenesis. A candidate for the Fat ligand, Dachsous is expressed in the posterior optic lobe, and its mutation was observed to cause a similar phenotype as fat mutation, although in a regionally restricted manner. We also show that Dachsous functions as the ligand in this pathway and genetically interacts with Fat in the optic lobe. These findings provide new insights into the function of the Fat/Hippo pathway, which regulates the ordered progression of neurogenesis in the complex nervous system.     

Genome sequence of Sphingomonas elodea ATCC 31461, a highly productive industrial strain of gellan gum

The commercial gelling agent gellan gum is a heteropolysaccharide produced by Sphingomonas elodea ATCC 31461. However, the genes involved in the biosynthesis, regulation, and modification of gellan gum have not been fully characterized. Here we describe the draft genome sequence of stain ATCC 31461 and major findings from its annotation.     

Comparative analysis of the role of small G proteins in cell migration and cell death: cytoprotective and promigratory effects of RalA

Small G protein superfamily consists of more than 150 members, and is classified into six families: the Ras, Rho, Rab, Arf, Ran, and RGK families. They regulate a wide variety of cell functions such as cell proliferation/differentiation, cytoskeletal reorganization, vesicle trafficking, nucleocytoplasmic transport and microtubule organization. The small G proteins have also been shown to regulate cell death/survival and cell shape. In this study, we compared the role of representative members of the six families of small G proteins in cell migration and cell death/survival, two cellular phenotypes that are associated with inflammation, tumorigenesis, and metastasis. Our results show that small G proteins of the six families differentially regulate cell death and cell cycle distribution. In particular, our results indicate that Rho family of small G proteins is antiapoptotic. Ras, Rho, and Ran families promoted cell migration. There was no significant correlation between the cell death- and cell migration-regulating activities of the small G proteins. Nevertheless, RalA was not only cytoprotective against multiple chemotherapeutic drugs, but also promigratory inducing stress fiber formation, which was accompanied by the activation of Akt and Erk pathways. Our study provides a framework for further systematic investigation of small G proteins in the perspectives of cell death/survival and motility in inflammation and cancer.     

19-Nor-2α-(3-hydroxypropyl)-1α,25-dihydroxyvitamin D3 (MART-10) is a potent cell growth regulator with enhanced chemotherapeutic potency in liver cancer cells

The discovery that the active form of vitamin D, 1α,25-dihydroxyvitamin D [1α,25(OH)₂D] can modulate cellular proliferation and differentiation of cancer cells has led to its potential application as a chemotherapeutic agent to treat a variety of cancers. However, the use of 1α,25(OH)₂D is limited due to its lethal side effect of hypercalcemia upon systemic administration. To overcome this drawback, numerous analogs have been synthesized. In this report, we examined the anti-proliferative activity of a new analog, 19-nor-2α-(3-hydroxypropyl)-1α,25(OH)₂D₃ (MART-10), in HepG2 liver cancer cells, and studied the potential mechanisms mediating this action. We found that MART-10 exhibited approximately 100-fold greater activity than 1α,25(OH)₂D₃ in inhibiting HepG2 cell proliferation as determined by cell number counting method. MART-10 was also approximately 100-fold more potent than 1α,25(OH)₂D₃ in the upregulation of p21 and p27, that in turn arrested HepG2 cells at the G₀/G₁ phase to a greater extent. Given that no active caspase 3 was detected and treatment with 1α,25(OH)₂D₃ or MART-10 did not further increase the fractions of apoptotic and necrosis cells over the controls, the growth-inhibitory effect of 1α,25(OH)₂D₃ and MART-10 on HepG2 cells may not involve apoptosis. Overall, our findings suggest that MART-10 is a good candidate as a novel therapeutic regimen against liver cancer. Further pre-clinical studies using animal models and the subsequent human clinical trials are warranted.