100 research outputs found
Molecular mechanism of basic calcium phosphate crystal-induced activation of human fibroblasts: Role of nuclear factor κB, activator protein 1, and protein kinase C
Synovial fluid basic calcium phosphate (BCP) crystals are markers of severe joint degeneration in osteoarthritis. BCP crystals cause mitogenesis of articular cells and stimulate matrix metalloprotease production, thus promoting degradation of articular tissues. Previous work suggested that BCP crystal-induced cell activation required intracellular crystal dissolution, induction of proto-oncogene expression, and activation of signal transduction pathways involving protein kinase C and mitogen-activated protein kinases. Here we further elucidate the mechanisms of BCP crystal-induced cell activation as BCP crystals activate transcription factors nuclear factor κB and activator protein I in human fibroblasts. We confirm the role of protein kinase C in BCP crystal-induced mitogenesis in human fibroblasts. In contrast, we demonstrate that BCP crystals do not activate signal transduction pathways involving protein tyrosine kinases or phosphatidylinositol 3-kinase. These data further define the mechanism of cell activation by BCP crystals and confirm its selectivity, an observation that may have therapeutic implications
Hydrophobic and ionic-interactions in bulk and confined water with implications for collapse and folding of proteins
Water and water-mediated interactions determine thermodynamic and kinetics of
protein folding, protein aggregation and self-assembly in confined spaces. To
obtain insights into the role of water in the context of folding problems, we
describe computer simulations of a few related model systems. The dynamics of
collapse of eicosane shows that upon expulsion of water the linear hydrocarbon
chain adopts an ordered helical hairpin structure with 1.5 turns. The structure
of dimer of eicosane molecules has two well ordered helical hairpins that are
stacked perpendicular to each other. As a prelude to studying folding in
confined spaces we used simulations to understand changes in hydrophobic and
ionic interactions in nano droplets. Solvation of hydrophobic and charged
species change drastically in nano water droplets. Hydrophobic species are
localized at the boundary. The tendency of ions to be at the boundary where
water density is low increases as the charge density decreases. Interaction
between hydrophobic, polar, and charged residue are also profoundly altered in
confined spaces. Using the results of computer simulations and accounting for
loss of chain entropy upon confinement we argue and then demonstrate, using
simulations in explicit water, that ordered states of generic amphiphilic
peptide sequences should be stabilized in cylindrical nanopores
A novel enzymatically-mediated drug delivery carrier for bone tissue engineering applications: combining biodegradable starch-based microparticles and differentiation agents
In many biomedical applications, the performance
of biomaterials depends largely on their degradation
behavior. For instance, in drug delivery applications, the
polymeric carrier should degrade under physiological
conditions slowly releasing the encapsulated drug. The aim
of this work was, therefore, to develop an enzymaticmediated
degradation carrier system for the delivery of
differentiation agents to be used in bone tissue engineering
applications. For that, a polymeric blend of starch with
polycaprolactone (SPCL) was used to produce a microparticle
carrier for the controlled release of dexamethasone
(DEX). In order to investigate the effect of enzymes on the
degradation behavior of the developed system and release
profile of the encapsulated osteogenic agent (DEX), the
microparticles were incubated in phosphate buffer solution
in the presence of a-amylase and/or lipase enzymes (at
physiological concentrations), at 37 C for different periods
of time. The degradation was followed by gravimetric
measurements, scanning electron microscopy (SEM) and
Fourier transformed infrared (FTIR) spectroscopy and the
release of DEX was monitored by high performance liquid
chromatography (HPLC). The developed microparticles
were shown to be susceptible to enzymatic degradation, as observed by an increase in weight loss and porosity with
degradation time when compared with control samples
(incubation in buffer only). For longer degradation times,
the diameter of the microparticles decreased significantly
and a highly porous matrix was obtained. The in vitro
release studies showed a sustained release pattern with
48% of the encapsulated drug being released for a period of
30 days. As the degradation proceeds, it is expected that
the remaining encapsulated drug will be completely
released as a consequence of an increasingly permeable
matrix and faster diffusion of the drug. Cytocompatibility
results indicated the possibility of the developed microparticles
to be used as biomaterial due to their reduced
cytotoxic effects
Factor XIIIA-expressing inflammatory monocytes promote lung squamous cancer through fibrin cross-linking
Lung cancer is the leading cause of cancer-related deaths worldwide, and lung squamous carcinomas (LUSC) represent about 30% of cases. Molecular aberrations in lung adenocarcinomas have allowed for effective targeted treatments, but corresponding therapeutic advances in LUSC have not materialized. However, immune checkpoint inhibitors in sub-populations of LUSC patients have led to exciting responses. Using computational analyses of The Cancer Genome Atlas, we identified a subset of LUSC tumors characterized by dense infiltration of inflammatory monocytes (IMs) and poor survival. With novel, immunocompetent metastasis models, we demonstrated that tumor cell derived CCL2-mediated recruitment of IMs is necessary and sufficient for LUSC metastasis. Pharmacologic inhibition of IM recruitment had substantial anti-metastatic effects. Notably, we show that IMs highly express Factor XIIIA, which promotes fibrin cross-linking to create a scaffold for LUSC cell invasion and metastases. Consistently, human LUSC samples containing extensive cross-linked fibrin in the microenvironment correlated with poor survival
Two Types of Planning in Neighborhoods
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68338/2/10.1177_0739456X8400300209.pd
De novo variants in the RNU4-2 snRNA cause a frequent neurodevelopmental syndrome
Around 60% of individuals with neurodevelopmental disorders (NDD) remain undiagnosed after comprehensive genetic testing, primarily of protein-coding genes1. Large genome-sequenced cohorts are improving our ability to discover new diagnoses in the non-coding genome. Here, we identify the non-coding RNA RNU4-2 as a syndromic NDD gene. RNU4-2 encodes the U4 small nuclear RNA (snRNA), which is a critical component of the U4/U6.U5 tri-snRNP complex of the major spliceosome2. We identify an 18 bp region of RNU4-2 mapping to two structural elements in the U4/U6 snRNA duplex (the T-loop and Stem III) that is severely depleted of variation in the general population, but in which we identify heterozygous variants in 115 individuals with NDD. Most individuals (77.4%) have the same highly recurrent single base insertion (n.64_65insT). In 54 individuals where it could be determined, the de novo variants were all on the maternal allele. We demonstrate that RNU4-2 is highly expressed in the developing human brain, in contrast to RNU4-1 and other U4 homologs. Using RNA-sequencing, we show how 5’ splice site usage is systematically disrupted in individuals with RNU4-2 variants, consistent with the known role of this region during spliceosome activation. Finally, we estimate that variants in this 18 bp region explain 0.4% of individuals with NDD. This work underscores the importance of non-coding genes in rare disorders and will provide a diagnosis to thousands of individuals with NDD worldwide
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