Biology subjects

Pawlak, E. N.

Publications and source records attributed to Pawlak, E. N..

3 recordsLinked to original sources

bioRxiv2019

GATA2 Expression by Intima-Infiltrating Macrophages Drives Early Atheroma Formation

Aberrant macrophage polarization is a major contributor to the onset and progression of atherosclerosis. Despite this, macrophage polarization during in early stages of human atherosclerotic disease is poorly understood. Using transcriptomic analysis of macrophages recovered from early-stage human atherosclerotic lesions, we have identified a unique gene expression profile dissimilar to that observed in later stages of disease that is characterized by upregulation of the hematopoietic transcription factor GATA2. GATA2 overexpression in vitro recapitulated defects observed in patient macrophages, including deficiencies in the uptake and processing of apoptotic cells, and in the catalysis of atherogenic protein modifications, with GATA2 knockdown abrogating these defects. Our data describe a previously unreported macrophage differentiation state present in early atheroma formation and identifies GATA2 as a driver of macrophage functional defects during the early stages of atherosclerosis in humans.

immunology↗

bioRxiv2018

PACS-1 and Adaptor Protein-1 Mediate ACTH Trafficking to the Regulated Secretory Pathway

The regulated secretory pathway is a specialized form of protein secretion found in endocrine and neuroendocrine cell types. Pro-opiomelanocortin (POMC) is a pro-hormone that utilizes this pathway to be trafficked to dense core secretory granules (DCSGs). Within this organelle, POMC is processed to multiple bioactive hormones that play key roles in cellular physiology. However, the complete set of cellular membrane trafficking proteins that mediate the correct sorting of POMC to DCSGs remain unknown. Here, we report the roles of the phosphofurin acidic cluster sorting protein - 1 (PACS-1) and the clathrin adaptor protein 1 (AP-1) in the targeting of POMC to DCSGs. Upon knockdown of PACS-1 and AP-1, POMC is readily secreted into the extracellular milieu and fails to be targeted to DCSGs.

cell biology↗

bioRxiv2018

Soluble CD93 is an Apoptotic Cell Opsonin Recognized by the αxβ2 Integrin

AO_SCPLOWBSTRACTC_SCPLOWEfferocytosis - the phagocytic removal of apoptotic cells - is essential for the maintenance of homeostasis and prevention of the inflammatory and autoimmune diseases which can follow the lysis of uncleared apoptotic cells. CD93 is a transmembrane glycoprotein previously implicated in efferocytosis and angiogenesis, and upon mutation, results in the onset of efferocytosis-associated diseases such as atherosclerosis and rheumatoid arthritis. CD93 is produced as a cell surface protein which is shed as soluble CD93, but it is unknown how CD93 mediates efferocytosis or whether its efferocytic activity is mediated by the soluble or membrane-bound form. Herein, we demonstrate that the membrane bound form of CD93 has no phagocytic, efferocytic, or tethering activity, whereas soluble CD93 potently opsonizes apoptotic cells but not a broad range of Gram-Negative, Gram-Positive or fungal microorganisms. Using mass spectrometry, we identified the x{beta}2 integrin as the receptor required for soluble CD93-mediated efferocytosis, and via deletion mutagenesis determined that soluble CD93 binds to apoptotic cells via its C-Type Lectin-Like domain, and to x{beta}2 by its EGF-like repeats. This bridging of apoptotic cells to the x{beta}2 integrin markedly enhanced efferocytosis by macrophages, and could be abrogated by knockdown of x{beta}2 integrin. Combined, these data elucidate the mechanism by which CD93 regulates efferocytosis and identify a previously unreported opsonin-receptor system utilized by the immune system for the efferocytic clearance of apoptotic cells.

immunology↗