Expression study of Krabbe Disease GALC missense variants - Insights from quantification profiles of residual enzyme activity, secretion and psychosine levels.

Krabbe disease (KD) is an autosomal recessive lysosomal storage disorder caused by loss-of-function mutations in the GALC gene, which encodes for the enzyme galactosylceramidase (GALC). GALC is crucial for myelin metabolism. Functional deficiency of GALC leads to toxic accumulation of psychosine, dysfunction and death of oligodendrocytes, and eventual brain demyelination. To date, 46 clinically-relevant, pathogenic GALC missense mutations (MMs) have been identified in KD patients. These MMs are present in ∼70% of KD cases reported over 8 published studies between 1996 - 2019. However, the mechanisms by which these MMs lead to GALC functional deficiency and their correlations with clinical phenotype remain poorly understood. To address this, we generated a GALC -knockout human oligodendrocytic cell line (MO3.13/ GALC -KO) using CRISPR-Cas9 method to assess GALC function and GALC secretion. We evaluated 5 polymorphic and 31 clinically-relevant MM variants (MMVs) using transient expression assays. Our results showed that 26 MMVs, including 10 co-variants with p.I562T, reduced GALC activity by 92% - 100% compared to wild-type GALC (WT-GALC). MMVs from infantile-onset KD patients produced < 2% of WT activity, whereas those associated with juvenile- and adult-onset cases retained up to 7% of WT activity. Residual GALC activity was correlated with mature, lysosomal GALC protein levels (Pearson r = 0.93, P<0.0001). Many low-activity MMVs did not correspondingly impair GALC secretion. Twenty-one of the 26 low-activity MMVs showed a 21% - 100% reduction in sec-GALC levels, indicating varying degrees of GALC mis-trafficking among these variants. Importantly, GALC activity among MMVs strongly correlates with clinical disease severity, based on the age of symptom onset in patients with either homozygous MM (Pearson r = 0.98, P<0.0001, n = 7) or compound heterozygous (Pearson r = 0.94, P<0.0001, n = 12) MM-null mutation genotypes. Thus, our data suggests that GALC activity could serve as a prognostic disease indicator under specific experimental conditions. We further investigated the impact of pathogenic MMVs on psychosine accumulation, a key biomarker for KD. Psychosine levels were 21-fold higher in mock control cells compared to WT-GALC transfected cells (mock = 0.349 pmol/mg, WT-GALC = 0.016 pmol/mg), but negatively correlated with GALC activity among pathogenic MMVs (Pearson r = -0.63, P < 0.01, n = 15). Although psychosine levels were higher in most MMVs associated with infantile-onset KD, no significant correlations with clinical onset were detected. Overall, our study provides a comprehensive quantitative analysis of the functional deficits and mis-trafficking associated with clinically-relevant GALC MMVs, enhancing our understanding of the molecular genetics and genotype-phenotype correlations of the GALC gene in Krabbe disease.

Dominant Circulating Cell-free Mycobacterial Proteins in In-use Machining Fluid and their Antigenicity Potential.

BACKGROUND: Occupational exposure to industrial Metalworking Fluid (MWF) colonized by Mycobacterium immunogenum (MI) has been associated with immune lung disease hypersensitivity pneumonitis (HP) in machinists. This warrants regular fluid monitoring for early detection of mycobacterial proteins, especially those with antigenic potential. OBJECTIVE: To detect and identify dominant MI proteins and antigens directly from the field-drawn in-use MWF using an integrated immunoproteomic-immunoinformatic approach. METHODS: An MI-positive MWF selected by DNA-based screening of several field-drawn MWF samples was cultured to isolate the colonizing strain and profiled for dominant circulating cell-free (ccf) MI proteins, including antigens using an integrated immunoproteomic (1D- and 2Dgel fractionation of seroreactive proteins combined with shotgun proteomic analysis using LC-MS/MS) and immunoinformatic strategy. RESULTS: A new MI strain (MJY-27) was identified. The gel fractionated MI protein bands (1Dgel) or spots (2D-gel) seroreactive with anti-MI sera probes (Rabbit and Patient sera) yielded 86 MI proteins, 29 of which showed peptide abundance. T-cell epitope analysis revealed high (90-100%) binding frequency for HLA-I & II alleles for 13 of the 29 proteins. Their antigenicity analysis revealed the presence of 6 to 37 antigenic determinants. Interestingly, one of the identified candidates corresponded to an experimentally validated strong B- and T-cell antigen (AgD) from our laboratory culture-based studies. CONCLUSION: This first report on dominant proteins, including putative antigens of M. immunogenum prevalent in field in-use MWF, is a significant step towards the overall goal of developing fluid monitoring for exposure and disease risk assessment for HP development in machining environments.

Predominantly Orphan Secretome in the Lung Pathogen Mycobacterium abscessus Revealed by a Multipronged Growth-Phase-Driven Strategy.

The emerging lung pathogen Mycobacterium abscessus is understudied for its virulence determinants and molecular targets for diagnosis and therapeutics. Here, we report a comprehensive secretome (600 proteins) of this species, which was identified using a multipronged strategy based on genetic/genomic, proteomic, and bioinformatic approaches. In-solution digested bottom-up proteomics from various growth phases identified a total of 517 proteins, while 2D-GE proteomics identified 33 proteins. A reporter-gene-fusion-based genomic library that was custom-generated in this study enabled the detection of 23 secretory proteins. A genome-wide survey for N-terminal signal sequences using bioinformatic tools (Psortb 2.0 and SignalP 3.0) combined with a strategy of the subtraction of lipoproteins and proteins containing multiple transmembrane domains yielded 116 secretory proteins. A homology search against the M. tuberculosis database identified nine additional secretory protein homologs that lacked a secretory signal sequence. Considering the little overlap (80 proteins) among the different approaches used, this study emphasized the importance of using a multipronged strategy for a comprehensive understanding of the secretome. Notably, the majority of the secreted proteins identified (over 50%) turned out to be "orphans" (those with no known functional homologs). The revelation of these species-specific orphan proteins offers a hitherto unexplored repertoire of potential targets for diagnostic, therapeutic, and vaccine research in this emerging lung pathogen.

Structural and functional fine mapping of cysteines in mammalian glutaredoxin reveal their differential oxidation susceptibility.

Protein-S-glutathionylation is a post-translational modification involving the conjugation of glutathione to protein thiols, which can modulate the activity and structure of key cellular proteins. Glutaredoxins (GLRX) are oxidoreductases that regulate this process by performing deglutathionylation. However, GLRX has five cysteines that are potentially vulnerable to oxidative modification, which is associated with GLRX aggregation and loss of activity. To date, GLRX cysteines that are oxidatively modified and their relative susceptibilities remain unknown. We utilized molecular modeling approaches, activity assays using recombinant GLRX, coupled with site-directed mutagenesis of each cysteine both individually and in combination to address the oxidizibility of GLRX cysteines. These approaches reveal that C8 and C83 are targets for S-glutathionylation and oxidation by hydrogen peroxide in vitro. In silico modeling and experimental validation confirm a prominent role of C8 for dimer formation and aggregation. Lastly, combinatorial mutation of C8, C26, and C83 results in increased activity of GLRX and resistance to oxidative inactivation and aggregation. Results from these integrated computational and experimental studies provide insights into the relative oxidizability of GLRX's cysteines and have implications for the use of GLRX as a therapeutic in settings of dysregulated protein glutathionylation.

Mitoquinone mesylate attenuates pathological features of lean and obese allergic asthma in mice.

Obesity is associated with severe, difficult-to-control asthma, and increased airway oxidative stress. Mitochondrial reactive oxygen species (mROS) are an important source of oxidative stress in asthma, leading us to hypothesize that targeting mROS in obese allergic asthma might be an effective treatment. Using a mouse model of house dust mite (HDM)-induced allergic airway disease in mice fed a low- (LFD) or high-fat diet (HFD), and the mitochondrial antioxidant MitoQuinone (MitoQ), we investigated the effects of obesity and ROS on HDM-induced airway inflammation, remodeling, and airway hyperresponsiveness (AHR). Obese allergic mice showed increased lung tissue eotaxin, airway tissue eosinophilia, and AHR compared with lean allergic mice. MitoQ reduced airway inflammation, remodeling, and hyperreactivity in both lean and obese allergic mice, and tissue eosinophilia in obese-allergic mice. Similar effects were observed with decyl triphosphonium (dTPP+), the hydrophobic cationic moiety of MitoQ lacking ubiquinone. HDM-induced oxidative sulfenylation of proteins was increased particularly in HFD mice. Although only MitoQ reduced sulfenylation of proteins involved in protein folding in the endoplasmic reticulum (ER), ER stress was attenuated by both MitoQ and dTPP+ suggesting the anti-allergic effects of MitoQ are mediated in part by effects of its hydrophobic dTPP+ moiety reducing ER stress. In summary, oxidative signaling is an important mediator of allergic airway disease. MitoQ, likely through reducing protein oxidation and affecting the UPR pathway, might be effective for the treatment of asthma and specific features of obese asthma.

Inhibition of PDIA3 in club cells attenuates osteopontin production and lung fibrosis.

BACKGROUND: The role of club cells in the pathology of idiopathic pulmonary fibrosis (IPF) is not well understood. Protein disulfide isomerase A3 (PDIA3), an endoplasmic reticulum-based redox chaperone required for the functions of various fibrosis-related proteins; however, the mechanisms of action of PDIA3 in pulmonary fibrosis are not fully elucidated. OBJECTIVES: To examine the role of club cells and PDIA3 in the pathology of pulmonary fibrosis and the therapeutic potential of inhibition of PDIA3 in lung fibrosis. METHODS: Role of PDIA3 and aberrant club cells in lung fibrosis was studied by analyses of human transcriptome dataset from Lung Genomics Research Consortium, other public resources, the specific deletion or inhibition of PDIA3 in club cells and blocking SPP1 downstream of PDIA3 in mice. RESULTS: PDIA3 and club cell secretory protein (SCGB1A1) signatures are upregulated in IPF compared with control patients. PDIA3 or SCGB1A1 increases also correlate with a decrease in lung function in patients with IPF. The bleomycin (BLM) model of lung fibrosis showed increases in PDIA3 in SCGB1A1 cells in the lung parenchyma. Ablation of Pdia3, specifically in SCGB1A1 cells, decreases parenchymal SCGB1A1 cells along with fibrosis in mice. The administration of a PDI inhibitor LOC14 reversed the BLM-induced parenchymal SCGB1A1 cells and fibrosis in mice. Evaluation of PDIA3 partners revealed that SPP1 is a major interactor in fibrosis. Blocking SPP1 attenuated the development of lung fibrosis in mice. CONCLUSIONS: Our study reveals a new relationship with distally localised club cells, PDIA3 and SPP1 in lung fibrosis and inhibition of PDIA3 or SPP1 attenuates lung fibrosis.

Ciliary Ca2+ pumps regulate intraciliary Ca2+ from the action potential and may co-localize with ciliary voltage-gated Ca2+ channels.

Calcium ions (Ca2+) entering cilia through the ciliary voltage-gated calcium channels (CaV) during the action potential causes reversal of the ciliary power stroke and backward swimming in Paramecium tetraurelia. How calcium is returned to the resting level is not yet clear. Our focus is on calcium pumps as a possible mechanism. There are 23 P. tetraurelia genes for calcium pumps that are members of the family of plasma membrane Ca2+ ATPases (PMCAs). They have domains homologous to those found in mammalian PMCAs. Of the 13 pump proteins previously identified in cilia, ptPMCA2a and ptPMCA2b are most abundant in the cilia. We used RNAi to examine which PMCA might be involved in regulating intraciliary Ca2+ after the action potential. RNAi for only ptPMCA2a and ptPMCA2b causes cells to significantly prolong their backward swimming, which indicates that Ca2+ extrusion in the cilia is impaired when these PMCAs are depleted. We used immunoprecipitations (IP) to find that ptPMCA2a and ptPMCA2b are co-immunoprecipitated with the CaV channel α1 subunits that are found only in the cilia. We used iodixanol (OptiPrep) density gradients to show that ptPMCA2a and ptPMCA2b and CaV1c are found in the same density fractions. These results suggest that ptPMCA2a and ptPMCA2b are located in the proximity of ciliary CaV channels.

Glutathionylation chemistry promotes interleukin-1 beta-mediated glycolytic reprogramming and pro-inflammatory signaling in lung epithelial cells.

Glycolysis is a well-known process by which metabolically active cells, such as tumor or immune cells meet their high metabolic demands. Previously, our laboratory has demonstrated that in airway epithelial cells, the pleiotropic cytokine, interleukin-1 beta (IL1B) induces glycolysis and that this contributes to allergic airway inflammation and remodeling. Activation of glycolysis is known to increase NADPH reducing equivalents generated from the pentose phosphate pathway, linking metabolic reprogramming with redox homeostasis. In addition, numerous glycolytic enzymes are known to be redox regulated. However, whether and how redox chemistry regulates metabolic reprogramming more generally remains unclear. In this study, we employed a multi-omics approach in primary mouse airway basal cells to evaluate the role of protein redox biochemistry, specifically protein glutathionylation, in mediating metabolic reprogramming. Our findings demonstrate that IL1B induces glutathionylation of multiple proteins involved in metabolic regulation, notably in the glycolysis pathway. Cells lacking Glutaredoxin-1 (Glrx), the enzyme responsible for reversing glutathionylation, show modulation of multiple metabolic pathways including an enhanced IL1B-induced glycolytic response. This was accompanied by increased secretion of thymic stromal lymphopoietin (TSLP), a cytokine important in asthma pathogenesis. Targeted inhibition of glycolysis prevented TSLP release, confirming the functional relevance of enhanced glycolysis in cells stimulated with IL1B. Collectively, data herein point to an intriguing link between glutathionylation chemistry and glycolytic reprogramming in epithelial cells and suggest that glutathionylation chemistry may represent a therapeutic target in pulmonary pathologies with perturbations in the glycolysis pathway.

Coactosin Phosphorylation Controls Entamoeba histolytica Cell Membrane Protrusions and Cell Motility.

Invasion of the colon wall by Entamoeba histolytica during amoebic dysentery entails migration of trophozoites through tissue layers that are rich in extracellular matrix. Transcriptional silencing of the E. histolytica surface metalloprotease EhMSP-1 produces hyperadherent less-motile trophozoites that are deficient in forming invadosomes. Reversible protein phosphorylation is often implicated in regulation of cell motility and invadosome formation. To identify such intermediaries of the EhMSP-1-silenced phenotype, here we compared the phosphoproteomes of EhMSP-1-silenced and vector control trophozoites by using quantitative tandem mass spectrometry-based proteomics. Six proteins were found to be differentially phosphorylated in EhMSP-1-silenced and control cells, including EhCoactosin, a member of the ADF/cofilin family of actin-binding proteins, which was more frequently phosphorylated at serine 147. Regulated overexpression of wild-type, phosphomimetic, and nonphosphorylatable EhCoactosin variants was used to test if phosphorylation functions in control of E. histolytica actin dynamics. Each of the overexpressed proteins colocalized with F-actin during E. histolytica phagocytosis. Nonetheless, trophozoites overexpressing an EhCoactosin phosphomimetic mutant formed more and poorly coordinated cell membrane protrusions compared to those in control or cells expressing a nonphosphorylatable mutant, while trophozoites overexpressing nonphosphorylatable EhCoactosin were significantly more motile within a model of mammalian extracellular matrix. Therefore, although EhCoactosin's actin-binding ability appeared unaffected by phosphorylation, EhCoactosin phosphorylation helps to regulate amoebic motility. These data help to understand the mechanisms underlying altered adherence and motility in EhMSP-1-silenced trophozoites and lay the groundwork for identifying kinases and phosphatases critical for control of amoebic invasiveness.IMPORTANCE Invasive amoebiasis, caused by the intestinal parasite Entamoeba histolytica, causes life-threatening diarrhea and liver abscesses, but, for unknown reasons, only approximately 10% of E. histolytica infections become symptomatic. A key requirement of invasion is the ability of the parasite to migrate through tissue layers. Here, we systematically looked for differences in protein phosphorylation between control parasites and a previously identified hyperadherent E. histolytica cell line that has reduced motility. We identified EhCoactosin, an actin-binding protein not previously known to be phosphoregulated, as one of the differentially phosphorylated proteins in E. histolytica and demonstrated that EhCoactosin phosphorylation functions in control of cell membrane dynamics and amoebic motility. This and the additional differentially phosphorylated proteins reported lay the groundwork for identifying kinases and phosphatases that regulate tissue invasiveness.

Dysregulation of the glutaredoxin/S-glutathionylation redox axis in lung diseases.

Glutathione is a major redox buffer, reaching millimolar concentrations within cells and high micromolar concentrations in airways. While glutathione has been traditionally known as an antioxidant defense mechanism that protects the lung tissue from oxidative stress, glutathione more recently has become recognized for its ability to become covalently conjugated to reactive cysteines within proteins, a modification known as S-glutathionylation (or S-glutathiolation or protein mixed disulfide). S-glutathionylation has the potential to change the structure and function of the target protein, owing to its size (the addition of three amino acids) and charge (glutamic acid). S-glutathionylation also protects proteins from irreversible oxidation, allowing them to be enzymatically regenerated. Numerous enzymes have been identified to catalyze the glutathionylation/deglutathionylation reactions, including glutathione S-transferases and glutaredoxins. Although protein S-glutathionylation has been implicated in numerous biological processes, S-glutathionylated proteomes have largely remained unknown. In this paper, we focus on the pathways that regulate GSH homeostasis, S-glutathionylated proteins, and glutaredoxins, and we review methods required toward identification of glutathionylated proteomes. Finally, we present the latest findings on the role of glutathionylation/glutaredoxins in various lung diseases: idiopathic pulmonary fibrosis, asthma, and chronic obstructive pulmonary disease.

Inclusion of grape marc in dairy cattle rations alters the bovine milk proteome.

Grape marc (GPM) is a viticulture by-product that is rich in secondary compounds, including condensed tannins (CT), and is used as a supplement in livestock feeding practices. The aim of this study was to determine whether feeding GPM to lactating dairy cows would alter the milk proteome through changes in nitrogen (N) partitioning. Ten lactating Holstein cows were fed a total mixed ration (TMR) top-dressed with either 1.5 kg dry matter (DM)/cow/day GPM (GPM group; n = 5) or 2.0 kg DM/cow/day of a 50:50 beet pulp: soy hulls mix (control group; n = 5). Characterization of N partitioning and calculation of N partitioning was completed through analysis of plasma urea-N, urine, feces, and milk urea-N. Milk samples were collected for general composition analysis, HPLC quantification of the high abundance milk proteins (including casein isoforms, α-lactalbumin, and ß-lactoglobulin) and liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis of the low abundance protein enriched milk fraction. No differences in DMI, N parameters, or calculated N partitioning were observed across treatments. Dietary treatment did not affect milk yield, milk protein or fat content or yield, or the concentrations of high abundance milk proteins quantified by HPLC analysis. Of the 127 milk proteins that were identified by LC-MS/MS analysis, 16 were affected by treatment, including plasma proteins and proteins associated with the blood-milk barrier, suggesting changes in mammary passage. Immunomodulatory proteins, including butyrophilin subfamily 1 member 1A and serum amyloid A protein, were higher in milk from GPM-fed cows. Heightened abundance of bioactive proteins in milk caused by dietary-induced shifts in mammary passage could be a feasible method to enhance the healthfulness of milk for both the milk-fed calf and human consumer. Additionally, the proteome shifts observed in this trial could provide a starting point for the identification of biomarkers suitable for use as indicators of mammary function.

Direct cysteine sulfenylation drives activation of the Src kinase.

The Src kinase controls aspects of cell biology and its activity is regulated by intramolecular structural changes induced by protein interactions and tyrosine phosphorylation. Recent studies indicate that Src is additionally regulated by redox-dependent mechanisms, involving oxidative modification(s) of cysteines within the Src protein, although the nature and molecular-level impact of Src cysteine oxidation are unknown. Using a combination of biochemical and cell-based studies, we establish the critical importance of two Src cysteine residues, Cys-185 and Cys-277, as targets for H2O2-mediated sulfenylation (Cys-SOH) in redox-dependent kinase activation in response to NADPH oxidase-dependent signaling. Molecular dynamics and metadynamics simulations reveal the structural impact of sulfenylation of these cysteines, indicating that Cys-277-SOH enables solvent exposure of Tyr-416 to promote its (auto)phosphorylation, and that Cys-185-SOH destabilizes pTyr-527 binding to the SH2 domain. These redox-dependent Src activation mechanisms offer opportunities for development of Src-selective inhibitors in treatment of diseases where Src is aberrantly activated.

Bacterial Lipoproteins Constitute the TLR2-Stimulating Activity of Serum Amyloid A.

Studies comparing endogenous and recombinant serum amyloid A (SAA) have generated conflicting data on the proinflammatory function of these proteins. In exploring this discrepancy, we found that in contrast to commercially sourced recombinant human SAA1 (hSAA1) proteins produced in Escherichia coli, hSAA1 produced from eukaryotic cells did not promote proinflammatory cytokine production from human or mouse cells, induce Th17 differentiation, or stimulate TLR2. Proteomic analysis of E. coli-derived hSAA1 revealed the presence of numerous bacterial proteins, with several being reported or probable lipoproteins. Treatment of hSAA1 with lipoprotein lipase or addition of a lipopeptide to eukaryotic cell-derived hSAA1 inhibited or induced the production of TNF-α from macrophages, respectively. Our results suggest that a function of SAA is in the binding of TLR2-stimulating bacterial proteins, including lipoproteins, and demand that future studies of SAA employ a recombinant protein derived from eukaryotic cells.

Avian lungs: A novel scaffold for lung bioengineering.

Allogeneic lung transplant is limited both by the shortage of available donor lungs and by the lack of suitable long-term lung assist devices to bridge patients to lung transplantation. Avian lungs have different structure and mechanics resulting in more efficient gas exchange than mammalian lungs. Decellularized avian lungs, recellularized with human lung cells, could therefore provide a powerful novel gas exchange unit for potential use in pulmonary therapeutics. To initially assess this in both small and large avian lung models, chicken (Gallus gallus domesticus) and emu (Dromaius novaehollandiae) lungs were decellularized using modifications of a detergent-based protocol, previously utilized with mammalian lungs. Light and electron microscopy, vascular and airway resistance, quantitation and gel analyses of residual DNA, and immunohistochemical and mass spectrometric analyses of remaining extracellular matrix (ECM) proteins demonstrated maintenance of lung structure, minimal residual DNA, and retention of major ECM proteins in the decellularized scaffolds. Seeding with human bronchial epithelial cells, human pulmonary vascular endothelial cells, human mesenchymal stromal cells, and human lung fibroblasts demonstrated initial cell attachment on decellularized avian lungs and growth over a 7-day period. These initial studies demonstrate that decellularized avian lungs may be a feasible approach for generating functional lung tissue for clinical therapeutics.

Mouse serum exosomal proteomic signature in response to asbestos exposure.

Asbestos-induced diseases like fibrosis and mesothelioma are very aggressive, without any treatment options. These diseases are diagnosed only at the terminal stages due to lack of early stage biomarkers. The recent discovery of exosomes as circulating biomarkers led us to look for exosomal biomarkers of asbestos exposure in mouse blood. In our model, mice were exposed to asbestos as a single bolus dose by oropharyngeal aspiration. Fifty-six days later blood was collected, exosomes were isolated from plasma and characterized and subjected to proteomic analysis using Tandem Mass Tag labeling. We identified many proteins, some of which were more abundant in asbestos exposed mouse serum exosomes, and three selected proteins were validated by immunoblotting. Our study is the first to show that serum exosomal proteomic signatures can reveal some important proteins relevant to asbestos exposure that have the potential to be validated as candidate biomarkers. We hope to extrapolate the positive findings of this study to humans in future studies.

Exosomes from asbestos-exposed cells modulate gene expression in mesothelial cells.

Asbestos exposure is a determinate cause of many diseases, such as mesothelioma, fibrosis, and lung cancer, and poses a major human health hazard. At this time, there are no identified biomarkers to demarcate asbestos exposure before the presentation of disease and symptoms, and there is only limited understanding of the underlying biology that governs asbestos-induced disease. In our study, we used exosomes, 30-140 nm extracellular vesicles, to gain insight into these knowledge gaps. As inhaled asbestos is first encountered by lung epithelial cells and macrophages, we hypothesize that asbestos-exposed cells secrete exosomes with signature proteomic cargo that can alter the gene expression of mesothelial cells, contributing to disease outcomes like mesothelioma. In the present study using lung epithelial cells (BEAS2B) and macrophages (THP-1), we first show that asbestos exposure causes changes in abundance of some proteins in the exosomes secreted from these cells. Furthermore, exposure of human mesothelial cells (HPM3) to these exosomes resulted in gene expression changes related to epithelial-to-mesenchymal transition and other cancer-related genes. This is the first report to indicate that asbestos-exposed cells secrete exosomes with differentially abundant proteins and that those exosomes have a gene-altering effect on mesothelial cells.-Munson, P., Lam, Y.-W., Dragon, J. MacPherson, M., Shukla, A. Exosomes from asbestos-exposed cells modulate gene expression in mesothelial cells.

TGF-ß1-induced deposition of provisional extracellular matrix by tracheal basal cells promotes epithelial-to-mesenchymal transition in a c-Jun NH2-terminal kinase-1-dependent manner.

Epithelial cells have been suggested as potential drivers of lung fibrosis, although the epithelial-dependent pathways that promote fibrogenesis remain unknown. Extracellular matrix is increasingly recognized as an environment that can drive cellular responses in various pulmonary diseases. In this study, we demonstrate that transforming growth factor-ß1 (TGF-ß1)-stimulated mouse tracheal basal (MTB) cells produce provisional matrix proteins in vitro, which initiate mesenchymal changes in subsequently freshly plated MTB cells via Rho kinase- and c-Jun NH2-terminal kinase (JNK1)-dependent processes. Repopulation of decellularized lung scaffolds, derived from mice with bleomycin-induced fibrosis or from patients with idiopathic pulmonary fibrosis, with wild-type MTB cells resulted in a loss of epithelial gene expression and augmentation of mesenchymal gene expression compared with cells seeded into decellularized normal lungs. In contrast, Jnk1-/- basal cells seeded into fibrotic lung scaffolds retained a robust epithelial expression profile, failed to induce mesenchymal genes, and differentiated into club cell secretory protein-expressing cells. This new paradigm wherein TGF-ß1-induced extracellular matrix derived from MTB cells activates a JNK1-dependent mesenchymal program, which impedes subsequent normal epithelial cell homeostasis, provides a plausible scenario of chronic aberrant epithelial repair, thought to be critical in lung fibrogenesis. This study identifies JNK1 as a possible target for inhibition in settings wherein reepithelialization is desired.

The lysosomal protein cathepsin L is a progranulin protease.

Haploinsufficiency of GRN, the gene encoding progranulin (PGRN), causes frontotemporal lobar degeneration (FTLD), the second most common cause of early-onset dementia. Receptor-mediated lysosomal targeting has been shown to regulate brain PGRN levels, and complete deficiency of PGRN is a direct cause of neuronal ceroid lipofuscinosis (NCL), a lysosomal storage disease. Here we show that the lysosomal cysteine protease cathepsin L (Cat L) can mediate the proteolytic cleavage of intracellular PGRN into poly-granulin and granulin fragments. Further, PGRN and Cat L co-localize in lysosomes of HEK293 cells, iPSC-derived neurons and human cortical neurons from human postmortem tissue. These data identify Cat L as a key intracellular lysosomal PGRN protease, and provides an intriguing new link between lysosomal dysfunction and FTLD.

Scaling Proteome-Wide Reactions of Activity-Based Probes.

Unified analysis of complex reactions of an activity-based probe with proteins in a proteome remains an unsolved challenge. We propose a power expression, rate = kobs[Probe]α, for scaling the progress of proteome-wide reactions and use the scaling factor (0 ≤ α ≤ 1) as an apparent, partial order with respect to the probe to measure the "enzyme-likeness" for a protein in reaction acceleration. Thus, α reports the intrinsic reactivity of the protein with the probe. When α = 0, the involved protein expedites the reaction to the maximal degree; when α = 1, the protein reacts with the probe via an unaccelerated, bimolecular reaction. The selectivity (ß) of the probe reacting with two proteins is calculated as a ratio of conversion factors (kobs values) for corresponding power equations. A combination of α and ß provides a tiered system for quantitatively assessing the probe efficacy; an ideal probe exhibits high reactivity with its protein targets (low in α) and is highly selective (high in ß) in forming the probe-protein adducts. The scaling analysis was demonstrated using proteome-wide reactions of HT-29 cell lysates with a model probe of threonine ß-lactone.

Development and Applications of a Calmodulin-Based Fusion Protein System for the Expression and Purification of WW and Zinc Finger Modules.

Calmodulin from Homo sapiens is an α-helical calcium-binding protein that expresses to high levels in E. coli. When the N-terminus of a calmodulin variant is bound to Ca2+, it undergoes a conformational change, exposing hydrophobic pockets. This property can be utilized for purification purposes, as these pockets bind to phenyl sepharose resin with high affinity. Washing with EDTA chelates the Ca2+ ions from the protein, inducing a conformational change back to the more folded state and eluting the protein from the column. We describe herein the use of a protein expression and purification technique using the calmodulin variant and a short linker for proteolytic cleavage by the mutant NIa-Pro tobacco etch virus protease. We have shown this approach to be useful in obtaining purified quantities of various small proteins that could not be expressed using other methods, including high enough concentrations of a designed WW domain protein for NMR structural analysis. We have also obtained promising results on the usefulness of this procedure to express and purify zinc finger proteins without the addition of zinc ions or other cofactors.