Mass Spectrometry-Based Identification of Extracellular Domains of Cell Surface N-Glycoproteins: Defining the Accessible Surfaceome for Immunophenotyping Stem Cells and Their Derivatives

Abstract Background Glioma stem cells (GSCs) are considered the initial cells of gliomas, contributing to therapeutic resistance. Patient-derived GSCs well recapitulate the heterogeneity of their parent glioma tissues, which can be classified into different subtypes. Likewise, previous works identified GSCs as two distinct subtypes, mesenchymal (MES) and proneural (PN) subtypes, and with general recognition, the MES subtype is considered a more malignant phenotype characterized by high invasion and radioresistance. Therefore, understanding the mechanisms involved in the MES phenotype is necessary for glioblastoma treatment. Methods Data for bioinformatic analysis were obtained from The Cancer Genome Atlas (TCGA) and The Gene Expression Omnibus (GEO) database. An antibody was used to block cell surface glucose-regulated protein 78 (csGRP78). Apoptosis and cell cycle analyses were performed to evaluate radiation damage. Immunofluorescence staining was applied to assess protein expression and distribution. Mass spectrometry combined with bioinformatic analysis was used to screen downstream molecules. Intracranial GSC-derived xenografts were established for in vivo experiments. Results Total GRP78 expression was associated with MES GSC stemness, and csGRP78 was highly expressed in MES GSCs. Targeting csGRP78 suppressed the self-renewal and radioresistance of MES GSCs in vitro and in vivo, accompanied by downregulation of the STAT3, NF-κB and C/EBPβ pathways. Mass spectrometry revealed the potential downstream β-site APP-cleaving enzyme 2 (BACE2), which was regulated by csGRP78 via lysosomal degradation. Knockdown of BACE2 inactivated NF-κB and C/EBPβ and significantly suppressed the tumorigenesis and radioresistance of MES GSCs in vitro and in vivo. Conclusions Cell surface GRP78 was preferentially expressed in MES GSCs and played a pivotal role in MES phenotype maintenance. Thus, blocking csGRP78 in MES GSCs with a high-specificity antibody might be a promising novel therapeutic strategy.

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T9. EPIGENETIC PROFILING IN SCHIZOPHRENIA DERIVED HUMAN INDUCED PLURIPOTENT STEM CELLS (HIPSCS) AND NEURONS

Schizophrenia Bulletin ◽

10.1093/schbul/sbaa029.569 ◽

2020 ◽

Vol 46 (Supplement_1) ◽

pp. S234-S234

Author(s):

Lorna Farrelly ◽

Shuangping Zhang ◽

Erin Flaherty ◽

Aaron Topol ◽

Nadine Schrode ◽

...

Keyword(s):

Gene Expression ◽

Mass Spectrometry ◽

Stem Cells ◽

Induced Pluripotent Stem Cells ◽

Pluripotent Stem Cells ◽

Neural Progenitor Cells ◽

Gene Expression Pattern ◽

Early Gene ◽

Label Free ◽

Induced Pluripotent

Abstract Background Schizophrenia (SCZ) is a severe psychiatric disorder affecting ~1% of the world’s population. It is largely heritable with genetic risk reflected by a combination of common variants of small effect and highly penetrant rare mutations. Chromatin modifications are known to play critical roles in the mediation of many neurodevelopmental processes, and, when disturbed, may also contribute to the precipitation of psychiatric disorders, such as SCZ. While a handful of candidate-based studies have measured changes in promoter-bound histone modifications, few mechanistic studies have been carried out to explore how these modifications may affect chromatin to precipitate behavioral phenotypes associated with the disease. Methods We applied an unbiased proteomics approach to evaluate the epigenetic landscape of SCZ in human induced pluripotent stem cells (hiPSC), neural progenitor cells (NPCs) and neurons from SCZ patients vs. matched controls. We utilized proteomics-based, label free liquid chromatography mass spectrometry (LC-MS/MS) on purified histones from these cells and confirmed our results by western blotting in postmortem SCZ cortical brain tissues. Furthermore we validated our findings with the application of histone interaction assays and structural and biophysical assessments to identify and confirm novel chromatin ‘readers’. To relate our findings to a SCZ phenotype we used a SCZ rodent model of prepulse inhibition (PPI) to perform pharmacological manipulations and behavioral assessments. Results Using label free mass spectrometry we performed PTM screening of hiPSCs, NPCs and matured neurons derived from SCZ patients and matched controls. We identified, amongst others, altered patterns of hyperacetylation in SCZ neurons. Additionally we identified enhanced binding of particular acetylation ‘reader’ proteins. Pharmacological inhibition of such proteins in an animal model of amphetamine sensitization ameliorated PPI deficits further validating this epigenetic signature in SCZ. Discussion Recent evidence indicates that relevance and patterns of acetylation in epigenetics advances beyond its role in transcription and small molecule inhibitors of these aberrant interactions hold promise as useful therapeutics. This study identifies a role for modulating gene expression changes associated with a SCZ epigenetic signature and warrants further investigation in terms of how this early gene expression pattern perhaps determines susceptibility or severity of the SCZ disease trajectory.

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Labile disulfide bonds are common at the leucocyte cell surface

Open Biology ◽

10.1098/rsob.110010 ◽

2011 ◽

Vol 1 (3) ◽

pp. 110010 ◽

Cited By ~ 51

Author(s):

Clive Metcalfe ◽

Peter Cresswell ◽

Laura Ciaccia ◽

Benjamin Thomas ◽

A. Neil Barclay

Keyword(s):

Mass Spectrometry ◽

Membrane Proteins ◽

Cell Surface ◽

Disulfide Bonds ◽

Reduction Process ◽

Cysteine Residue ◽

Surface Proteins ◽

Protein Activity ◽

Functional Changes ◽

Reducing Conditions

Redox conditions change in events such as immune and platelet activation, and during viral infection, but the biochemical consequences are not well characterized. There is evidence that some disulfide bonds in membrane proteins are labile while others that are probably structurally important are not exposed at the protein surface. We have developed a proteomic/mass spectrometry method to screen for and identify non-structural, redox-labile disulfide bonds in leucocyte cell-surface proteins. These labile disulfide bonds are common, with several classes of proteins being identified and around 30 membrane proteins regularly identified under different reducing conditions including using enzymes such as thioredoxin. The proteins identified include integrins, receptors, transporters and cell–cell recognition proteins. In many cases, at least one cysteine residue was identified by mass spectrometry as being modified by the reduction process. In some cases, functional changes are predicted (e.g. in integrins and cytokine receptors) but the scale of molecular changes in membrane proteins observed suggests that widespread effects are likely on many different types of proteins including enzymes, adhesion proteins and transporters. The results imply that membrane protein activity is being modulated by a ‘redox regulator’ mechanism.

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Neonatal stem cells exhibit specific characteristics in function, proliferation, and cellular signaling that distinguish them from their adult counterparts

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00031.2008 ◽

2008 ◽

Vol 294 (5) ◽

pp. R1491-R1497 ◽

Cited By ~ 14

Author(s):

Troy A. Markel ◽

Meijing Wang ◽

Paul R. Crisostomo ◽

Maiuxi C. Manukyan ◽

Jeffrey A. Poynter ◽

...

Keyword(s):

Stem Cells ◽

Cell Surface ◽

Surface Markers ◽

Cell Surface Markers ◽

Local Inflammatory Response ◽

Cell Counts ◽

Marrow Mesenchymal Stem Cells ◽

Growth Factor Production ◽

Erk Inhibition ◽

Different Levels

Stem cells may be a novel treatment modality for organ ischemia, possibly through beneficial paracrine mechanisms. Stem cells from older hosts have been shown to exhibit decreased function during stress. We therefore hypothesized that 1) neonatal bone marrow mesenchymal stem cells (nBMSCs) would produce different levels of IL-6, VEGF, and IGF-1 compared with adults (aBMSCs) when stimulated with TNF or LPS; 2) differences in cytokines would be due to distinct cellular characteristics, such as proliferation or pluripotent potential; and 3) differences in cytokines would be associated with differences in p38 MAPK and ERK signaling within nBMSCs. BMSCs were isolated from adult and neonatal mice. Cells were exposed to TNF or LPS with or without p38 or ERK inhibition. Growth factors were measured via ELISA, proliferation via daily cell counts, cell surface markers via flow cytometry, and pluripotent potential via alkaline phosphatase activity. nBMSCs produced lower levels of IL-6 and VEGF, but higher levels of IGF-1 under basal conditions, as well as after stimulation with TNF, but not LPS. Neonatal and adult BMSCs had similar pluripotent potentials and cell surface markers, but nBMSCs proliferated faster. Furthermore, p38 and ERK appeared to play a more substantial role in nBMSC cytokine and growth factor production. Neonatal stem cells may aid in decreasing the local inflammatory response during ischemia, and could possibly be expanded more rapidly than adult cells prior to therapeutic use.

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Isolation, Culture and Identification of Bovine Skeletal Stem Cells

Journal of Biomaterials and Tissue Engineering ◽

10.1166/jbt.2021.2816 ◽

2021 ◽

Vol 11 (12) ◽

pp. 2337-2345

Author(s):

Junhui Lai ◽

Qin Yang ◽

Ruining Liang ◽

Weijun Guan ◽

Xiuxia Li

Keyword(s):

Stem Cells ◽

Cell Surface ◽

Bone Formation ◽

Growth Plate ◽

Bone Development ◽

Long Bone ◽

Biological Characterization ◽

Self Renewal ◽

And Cartilage

The growth plate is essential in long bone formation and contains a wealth of skeletal stem cells (SSCs). Though the origin and the mechanism for SSCs generation remain uncertain, recent studies demonstrate the transition from cartilage to bone that in the lineage for bone development. SSCs possesses the ability to differentiate into bone and cartilage in vitro. In this research, we aimed to isolate and culture the skeletal stem cells from bovine cattle and then studied its biological characterization. The results showed that these bovine SSCs are positive for PDPN+CD73+CD164+CD90+CD44+ cell surface bio-markers, they are capable of self-renewal and differentiation. Our dates proved that SSCs exists in bovine’s long bone.

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