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

Abstract

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.

Mechanisms of viral persistence in the brain and therapeutic approaches

“…Virulence factors can interfere with major histocompatibility complex (MHC) class I and class II molecules by either downregulating their production or by preventing the trafficking of molecules to the plasma membrane. For example, both HIV and influenza A sequester MHC class I molecules in the cytoplasm [71,72], whereas influenza A and human cytomegalovirus downregulate expression of MHC class I molecules [71,73]. MHC class II molecules are also targeted by viruses through diverse strategies (recently reviewed in [74]).…”

PACS-1 and adaptor protein-1 mediate ACTH trafficking to the regulated secretory pathway

“…(Leica, Wetzlar, Germany), and images were deconvolved using the advanced fluorescence application on the Leica Application Suite software. Co-localization analysis was performed using the Pearson's correlation coefficient from the ImageJ plugin JACoP, as described previously [21].…”

“…Super-resolution imaging was performed as described previously [21]. Briefly, cells were mounted, and imaged in a depression slide containing 100mM cysteamine (Sigma Aldrich).…”

“…GFP and AlexaFluor 647 fluorophores were excited using 488 nm and 647 nm laser lines respectively. Resulting images were quantified using the spatial association analysis MIiSR software, as previously described [21] (Available for download:…”

PACS‐1 contains distinct motifs for nuclear‐cytoplasmic transport and interacts with the RNA‐binding protein PTBP1 in the nucleus and cytosol

“…The phosphofurin acidic cluster sorting (PACS) protein family is comprised of cytosolic membrane trafficking proteins within the secretory/endocytic pathway [1,2]. PACS‐1 is a critical protein that mediates membrane protein trafficking in vertebrates by binding to diverse cargo and trafficking machinery, including the adaptor protein‐1 complex, to ensure the proper cytoplasmic localization of numerous proteins [3–5]. Canonically, PACS‐1 is necessary to recycle the endoprotease, furin, from endosomes to the trans‐Golgi network (TGN) and sort the mannose‐6‐phosphate receptor to lysosomes [6,7].…”