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Tan A. Nguyen

Bio: Tan A. Nguyen is an academic researcher from University of California, San Francisco. The author has contributed to research in topics: Secretion & Receptor tyrosine kinase. The author has an hindex of 1, co-authored 3 publications receiving 12 citations.

Papers
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Journal ArticleDOI
13 May 2021-Cell
TL;DR: In this paper, a membraneless, protein granule-based subcellular structure that can organize RTK/RAS/MAPK signaling in cancer was uncovered, and the structure was used for organizing oncogenic RTK and RAS signaling.

69 citations

Posted ContentDOI
12 Aug 2021-bioRxiv
TL;DR: In this article, a secretory autophagy pathway upregulated in response to endolysosomal inhibition that mediates the EVP-associated extracellular release of autophagic cargo receptors, including p62/SQSTM1.
Abstract: The endosome-lysosome (endolysosome) system plays central roles in both autophagic degradation and secretory pathways, including the exocytic release of extracellular vesicles and particles (EVPs). Although previous work has revealed important interconnections between autophagy and EVP-mediated secretion, our molecular understanding of these secretory events during endolysosome inhibition remains incomplete. Here, we delineate a secretory autophagy pathway upregulated in response to endolysosomal inhibition that mediates the EVP-associated extracellular release of autophagic cargo receptors, including p62/SQSTM1. This extracellular secretion is highly regulated and critically dependent on multiple ATGs required for the progressive steps of early autophagosome formation as well as Rab27a-dependent exocytosis. Furthermore, the disruption of autophagosome maturation, either due to genetic inhibition of the autophagosome-to-autolyosome fusion machinery or blockade via the SARS-CoV2 viral protein ORF3a, is sufficient to induce robust EVP-associated secretion of autophagy cargo receptors. Finally, we demonstrate that this ATG-dependent, EVP-mediated secretion pathway buffers against the intracellular accumulation of autophagy cargo receptors when classical autophagic degradation is impaired. Based on these results, we propose that secretory autophagy via EVPs functions as an alternate route to clear sequestered material and maintain proteostasis in response to endolysosomal dysfunction or impaired autophagosome maturation.

6 citations

Journal ArticleDOI
TL;DR: A groundbreaking insight is provided into vesicle-mediated UPS via the transmembrane channel protein, TMED-10, in a process termed TMED10-channeled UPS (THU), suggesting that THU is distinct from and independent of the previously described GSDMD pore-forming secretion pathway.
Abstract: Cytosolic proteins lacking a signal peptide are often loaded into vesicles and secreted via unconventional protein secretion pathways. A recent paper in Cell identifies the transmembrane protein TMED10 as a protein channel for the vesicular translocation and secretion of mature IL-1β and other leaderless cargoes. Traditionally, protein secretion in eukaryotes involves the recognition of a signal peptide and the translocation and export of the protein through the ER-Golgi via the translocon SEC61 and COPII and COPI vesicles. Alternatively, numerous cytosolic proteins lacking a signal peptide, termed leaderless proteins, are secreted into the extracellular milieu through a diverse cellular process, collectively termed unconventional protein secretion (UPS). Leaderless proteins can directly translocate across the plasma membrane via pores (type I unconventional secretion) or ATP-binding cassette (ABC) transporters (type II); alternatively, they are loaded and trafficked through vesicular compartments which are delivered to the plasma membrane (type III). Precisely understanding how these leaderless cargoes are loaded into vesicular intermediates remains a fundamental question in the field. Zhang and colleagues now provide a groundbreaking insight into vesicle-mediated UPS via the transmembrane channel protein, TMED-10, in a process termed TMED10-channeled UPS (THU). A highly investigated protein secreted via UPS pathways is the pro-inflammatory cytokine IL-1β, which is catalytically processed to a mature form (mIL-1β) and released upon specific stimuli such as inflammasome activation and pyroptosis. Employing an elegant mass spectrometry approach, the authors identify 11 candidate transmembrane proteins that interact with mIL-1β during its translocation into vesicular carriers. Subsequent loss-offunction experiments reveal that loss of TMED10 impairs secretion of mIL-1β in macrophage and neutrophil cell lines. Importantly, TMED10 does not impact secretion of IL-1β through gasdermin D (GSDMD), suggesting that THU is distinct from and independent of the previously described GSDMD pore-forming secretion pathway. However, the relative physiological contribution of GSDMD versus TMED10-mediated IL-β release remains unclear. Nevertheless, conditional deletion of TMED10 in myeloid cells of mice results in reduced serum IL-1β and prolonged survival in a model of cecal ligation and puncture (CLP)-induced septic shock. An important follow-up will be to determine whether inhibiting IL-1β secretion via THU has therapeutic potential for the treatment of various human inflammatory diseases. TMED10 contains a single transmembrane domain, a luminal signal peptide (SS), a Golgi dynamics (GOLD) domain, a coil-coil (CC) domain and a C-terminal tail (CT) facing the cytoplasm. Using a series of truncation mutants, the authors uncover that the CT domain of TMED10 directly interacts with and is required for the secretion of mIL-1β and other known UPS cargoes. Interestingly, two proteins previously shown to be secreted via UPS in a TMED10-dependent manner, Tau and Annexin A1, do not interact with TMED-CT, raising the possibility that TMED10 may indirectly regulate the secretion of such UPS targets. Consistent with this notion, the authors identify a putative TMED10 recognition motif within mIL-1β termed ‘motif 1’. Mutation of this motif results in reduced secretion of mIL-1β, while fusion of this TMED10 recognition motif to an mCherry reporter is sufficient to promote interaction with TMED10 and the subsequent secretion of mCherry via THU. Remarkably, the authors note that the secretion of other leaderless cargoes, such as HMGB1 and αsynuclein, are not regulated by THU. Future mutational and functional studies will undoubtedly shed further light on the conservation of this identified motif across other known UPS cargoes and potentially lead to therapeutic strategies to modulate the unconventional secretion of pro-inflammatory cytokines or pathogenic protein aggregates. In previous work, the authors observed that the vesicular translocation of IL-1β requires an initial protein unfolding step and the association with the chaperone protein HSP90 via the recognition of two KFERQ-like sequences. This also appears to be the case for TMED10-mediated IL-1β secretion since both predenaturation of mIL-1β with urea and HSP90A overexpression enhance mIL-1β vesicular entry and secretion. Notably, previous studies implicated a secretory autophagy pathway, in which mIL-1β (but not pro-IL-1β) was incorporated within the intermembrane space of an autophagosome-like vesicular intermediate and subsequently secreted extracellularly. Despite these parallels, the relationship between THU and secretory autophagy remains unclear. Notably, TMED10 co-localizes with the ER-Golgi intermediate compartment (ERGIC) and mediates entry of mIL-1β and other UPS cargoes including mIL-1a, mIL-36a, mIL-36RA, mIL-37, mIL-38, and HSPB5. Further studies are needed to illuminate whether TMED10-mediated residing of cargoes within the ERGIC can intersect with secretory autophagosomes, multivesicular bodies (MVBs) or the recently described LC3-dependent extracellular vesicle loading and secretion (LDELS) pathway. Finally, the authors further characterize the mechanism by which TMED10, a single transmembrane protein, is able to translocate diverse proteins of varying sizes. Cross-linking experiments reveal that TMED10 can form higher order oligomeric structures following the production of mIL-1β in THP-1 cells. Interestingly, this oligomerization is both dependent on and induced by the presence of UPS competent cargo; accordingly, enforced expression of TMED10-dependent cargoes such as mIL-1β, mIL-1α and HSPB5 is sufficient to drive TMED10 oligomerization. Furthermore, the recognition of motif 1 via the CT domain of TMED10 leads to the stabilization of the TMED10 channel pore, which gradually monomerizes following secretion.

3 citations


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Journal ArticleDOI
TL;DR: In this article, a review summarises the most recent understanding of fundamental aspects of KRAS, the relationship between the KRAS mutations and tumour immune evasion, and new progress in targeting KRAS (G12C) particularly KRAS.
Abstract: Cancer is the leading cause of death worldwide, and its treatment and outcomes have been dramatically revolutionised by targeted therapies. As the most frequently mutated oncogene, Kirsten rat sarcoma viral oncogene homologue (KRAS) has attracted substantial attention. The understanding of KRAS is constantly being updated by numerous studies on KRAS in the initiation and progression of cancer diseases. However, KRAS has been deemed a challenging therapeutic target, even "undruggable", after drug-targeting efforts over the past four decades. Recently, there have been surprising advances in directly targeted drugs for KRAS, especially in KRAS (G12C) inhibitors, such as AMG510 (sotorasib) and MRTX849 (adagrasib), which have obtained encouraging results in clinical trials. Excitingly, AMG510 was the first drug-targeting KRAS (G12C) to be approved for clinical use this year. This review summarises the most recent understanding of fundamental aspects of KRAS, the relationship between the KRAS mutations and tumour immune evasion, and new progress in targeting KRAS, particularly KRAS (G12C). Moreover, the possible mechanisms of resistance to KRAS (G12C) inhibitors and possible combination therapies are summarised, with a view to providing the best regimen for individualised treatment with KRAS (G12C) inhibitors and achieving truly precise treatment.

117 citations

Journal ArticleDOI
TL;DR: In this paper , the formation of biomolecular condensates via liquid-liquid phase separation (LLPS) has recently emerged as a widespread mechanism underlying the spatiotemporal coordination of biological activities in cells.
Abstract: Cancer is a disease of uncontrollably reproducing cells. It is governed by biochemical pathways that have escaped the regulatory bounds of normal homeostatic balance. This balance is maintained through precise spatiotemporal regulation of these pathways. The formation of biomolecular condensates via liquid-liquid phase separation (LLPS) has recently emerged as a widespread mechanism underlying the spatiotemporal coordination of biological activities in cells. Biomolecular condensates are widely observed to directly regulate key cellular processes involved in cancer cell pathology, and the dysregulation of LLPS is increasingly implicated as a previously hidden driver of oncogenic activity. In this Perspective, we discuss how LLPS shapes the biochemical landscape of cancer cells.

57 citations

Journal ArticleDOI
TL;DR: In this article , the formation of biomolecular condensates via liquid-liquid phase separation (LLPS) has recently emerged as a widespread mechanism underlying the spatiotemporal coordination of biological activities in cells.
Abstract: Cancer is a disease of uncontrollably reproducing cells. It is governed by biochemical pathways that have escaped the regulatory bounds of normal homeostatic balance. This balance is maintained through precise spatiotemporal regulation of these pathways. The formation of biomolecular condensates via liquid-liquid phase separation (LLPS) has recently emerged as a widespread mechanism underlying the spatiotemporal coordination of biological activities in cells. Biomolecular condensates are widely observed to directly regulate key cellular processes involved in cancer cell pathology, and the dysregulation of LLPS is increasingly implicated as a previously hidden driver of oncogenic activity. In this Perspective, we discuss how LLPS shapes the biochemical landscape of cancer cells.

53 citations

Journal ArticleDOI
TL;DR: Wang et al. as discussed by the authors found that EML4-ALK variant 1 (exon 1-13 fused to exon 20-29 of ALK) forms condensates via phase separation in the cytoplasm of various human cancer cell lines.
Abstract: EML4-ALK fusion, observed in about 3%-7% of human lung adenocarcinoma, is one of the most important oncogenic drivers in initiating lung tumorigenesis. However, it still remains largely unknown about how EML4-ALK fusion exactly fires downstream signaling and drives lung cancer formation. We here find that EML4-ALK variant 1 (exon 1-13 of EML4 fused to exon 20-29 of ALK) forms condensates via phase separation in the cytoplasm of various human cancer cell lines. Using two genetically engineered mouse models (GEMMs), we find that EML4-ALK variant 1 can drive lung tumorigenesis and these murine tumors, as well as primary tumor-derived organoids, clearly show the condensates of EML4-ALK protein, further supporting the findings from in vitro study. Mutation of multiple aromatic residues in EML4 region significantly impairs the phase separation of EML4-ALK and dampens the activation of the downstream signaling pathways, especially the STAT3 phosphorylation. Importantly, it also significantly decreases cancer malignant transformation and tumor formation. These data together highlight an important role of phase separation in orchestrating EML4-ALK signaling and promoting tumorigenesis, which might provide new clues for the development of clinical therapeutic strategies in treating lung cancer patients with the EML4-ALK fusion.

25 citations

Journal ArticleDOI
TL;DR: In this paper, the authors highlight recent studies that advance our understanding of how phase separation impacts the organization of biochemical processes, with a particular focus on the tools used to study the functional impact of phase separation.

22 citations