Browsing by Author "Anthony, Adam J."

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    CDMS Analysis of Intact 19S, 20S, 26S, and 30S Proteasomes: Evidence for Higher-Order 20S Assemblies at a Low pH†
    (American Chemical Society, 2023) Anthony, Adam J.; Gautam, Amit K. S.; Miller, Lohra M.; Ma, Yiran; Hardwick, Anya G.; Sharma, Anu; Ghatak, Subhadip; Matouschek, Andreas; Jarrold, Martin F.; Clemmer, David E.; Surgery, School of Medicine
    Charge detection mass spectrometry (CDMS) was examined as a means of studying proteasomes. To this end, the following masses of the 20S, 19S, 26S, and 30S proteasomes from Saccharomyces cerevisiae (budding yeast) were measured: m(20S) = 738.8 ± 2.9 kDa, m(19S) = 926.2 ± 4.8 kDa, m(26S) = 1,637.0 ± 7.6 kDa, and m(30S) = 2,534.2 ± 10.8 kDa. Under some conditions, larger (20S)x (where x = 1 to ∼13) assemblies are observed; the 19S regulatory particle also oligomerizes, but to a lesser extent, forming (19S)x complexes (where x = 1 to 4, favoring the x = 3 trimer). The (20S)x oligomers are favored in vitro, as the pH of the solution is lowered (from 7.0 to 5.4, in a 20 mM ammonium acetate solution) and may be related to in vivo proteasome storage granules that are observed under carbon starvation. From measurements of m(20S)x (x = 1 to ∼13) species, it appears that each multimer retains all 28 proteins of the 20S complex subunit. Several types of structures that might explain the formation of (20S)x assemblies are considered. We stress that each structural type [hypothetical planar, raft-like geometries (where individual proteasomes associate through side-by-side interactions); elongated, rodlike geometries (where subunits are bound end-to-end); and geometries that are roughly spherical (arising from aggregation through nonspecific subunit interactions)] is highly speculative but still interesting to consider, and a short discussion is provided. The utility of CDMS for characterizing proteasomes and related oligomers is discussed.
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    Nanoscopic and Functional Characterization of Keratinocyte-Originating Exosomes in the Wound Fluid of Non-Diabetic and Diabetic Chronic Wound Patients
    (Elsevier, 2023) Guda, Poornachander R.; Sharma, Anu; Anthony, Adam J.; ElMasry, Mohamed S.; Couse, Andrew D.; Das Ghatak, Piya; Das, Amitava; Timsina, Lava; Trinidad, Jonathan C.; Roy, Sashwati; Clemmer, David E.; Sen, Chandan K.; Ghatak, Subhadip; Surgery, School of Medicine
    Exosomes, a class of extracellular vesicles of endocytic origin, play a critical role in paracrine signaling for successful cell-cell crosstalk in vivo. However, limitations in our current understanding of these circulating nanoparticles hinder efficient isolation, characterization, and downstream functional analysis of cell-specific exosomes. In this work, we sought to develop a method to isolate and characterize keratinocyte-originated exosomes (hExoκ) from human chronic wound fluid. Furthermore, we studied the significance of hExoκ in diabetic wounds. LC-MS-MS detection of KRT14 in hExoκ and subsequent validation by Vesiclepedia and Exocarta databases identified surface KRT14 as a reliable marker of hExoκ. dSTORM nanoimaging identified KRT14+ extracellular vesicles (EVκ) in human chronic wound fluid, 23% of which were of exosomal origin. An immunomagnetic two-step separation method using KRT14 and tetraspanin antibodies successfully isolated hExoκ from the heterogeneous pool of EV in chronic wound fluid of 15 non-diabetic and 22 diabetic patients. Isolated hExoκ (Ø75–150nm) were characterized per EV-track guidelines. dSTORM images, analyzed using online CODI followed by independent validation using Nanometrix, revealed hExoκ Ø as 80–145nm. The abundance of hExoκ was low in diabetic wound fluids and negatively correlated with patient HbA1c levels. The hExoκ isolated from diabetic wound fluid showed a low abundance of small bp RNA (<200 bp). Raman spectroscopy underscored differences in surface lipids between non-diabetic and diabetic hExoκ Uptake of hExoκ by monocyte-derived macrophages (MDM) was low for diabetics versus non-diabetics. Unlike hExoκ from non-diabetics, the addition of diabetic hExoκ to MDM polarized with LPS and INFγ resulted in sustained expression of iNOS and pro-inflammatory chemokines known to recruit macrophage (mϕ) This work provides maiden insight into the structure, composition, and function of hExoκ from chronic wound fluid thus providing a foundation for the study of exosomal malfunction under conditions of diabetic complications such as wound chronicity.