Emma L. Robinson, Charles A. Tharp, Rushita A. Bagchi, Timothy A. McKinsey
Widespread alterations in RNA alternative splicing (AS) have been identified in adult gliomas. However, their regulatory mechanism, biological significance, and therapeutic potential remain largely elusive. Here, using a computational approach with both bulk and single cell RNA-sequencing, we uncover a prognostic AS signature linked with neural developmental hierarchies. Using advanced iPSC glioma models driven by glioma driver mutations, we show that this AS signature could be enhanced by EGFRvIII and inhibited by in situ IDH1 mutation. Functional validation of two isoform switching events in CERS5 and MPZL1 shows regulations of sphingolipid metabolism and SHP2 signaling, respectively. Analysis of upstream RNA binding proteins reveals PTBP1 as a key regulator of the AS signature where targeting of PTBP1 suppresses tumor growth and promotes the expression of a neuron marker TUJ1 in glioma stem-like cells. Overall, our data highlights the role of AS in impacting glioma malignance and heterogeneity and its potential as a therapeutic vulnerability for treating adult gliomas.
Xiao Song, Deanna Tiek, Shunichiro Miki, Tianzhi Huang, Minghui Lu, Anshika Goenka, Rebeca P. Iglesia, Xiaozhou Yu, Runxin Wu, Maya N. Walker, Chang Zeng, Hardik Shah, Shao Huan Samuel Weng, Allen Huff, Wei Zhang, Tomoyuki Koga, Christopher G. Hubert, Craig M. Horbinski, Frank F. Furnari, Bo Hu, Shi-Yuan Cheng
Cancer cells exhibit heightened secretory states that drive tumor progression. Here, we identify a chromosome 3q amplicon that serves as a platform for secretory regulation in cancer. The 3q amplicon encodes multiple Golgi-resident proteins, including the scaffold Golgi integral membrane protein 4 (GOLIM4) and the ion channel ATPase Secretory Pathway Ca2+ Transporting 1 (ATP2C1). We show that GOLIM4 recruits ATP2C1 and Golgi phosphoprotein 3 (GOLPH3) to coordinate calcium-dependent cargo loading and Golgi membrane bending and vesicle scission. GOLIM4 depletion disrupts the protein complex, resulting in a secretory blockade that inhibits the progression of 3q-amplified malignancies. In addition to its role as a scaffold, GOLIM4 maintains intracellular manganese (Mn) homeostasis by binding excess Mn in the Golgi lumen, which initiates the routing of Mn-bound GOLIM4 to lysosomes for degradation. We show that Mn treatment inhibits the progression of multiple types of 3q-amplified malignancies by degrading GOLIM4, resulting in a secretory blockade that interrupts pro-survival autocrine loops and attenuates pro-metastatic processes in the tumor microenvironment. Potentially underlying the selective activity of Mn against 3q-amplified malignancies, ATP2C1 co-amplification increases Mn influx into the Golgi lumen, resulting in a more rapid degradation of GOLIM4. These findings show that functional cooperativity between co-amplified genes underlies heightened secretion and a targetable secretory addiction in 3q-amplified malignancies.
Xiaochao Tan, Shike Wang, Guan-Yu Xiao, Chao Wu, Xin Liu, Biyao Zhou, Jiang Yu, Dzifa Yawa Duose, Yuanxin Xi, Jing Wang, Kunika Gupta, Apar Pataer, Jack A. Roth, Michael P. Kim, Fengju Chen, Chad J. Creighton, William K. Russell, Jonathan M. Kurie
Regulated exocytosis is initiated by increased Ca2+ concentrations in close spatial proximity to secretory granules, which is effectively prevented when the cell is at rest. Here we showed that exocytosis of zymogen granules in acinar cells was driven by Ca2+ directly released from acidic Ca2+ stores including secretory granules through NAADP-activated two-pore channels (TPCs). We identified OCaR1 (encoded by Tmem63a) as an organellar Ca2+ regulator protein integral to the membrane of secretory granules that controlled Ca2+ release via inhibition of TPC1 and TPC2 currents. Deletion of OCaR1 led to extensive Ca2+ release from NAADP-responsive granules under basal conditions as well as upon stimulation of GPCR receptors. Moreover, OCaR1 deletion exacerbated the disease phenotype in murine models of severe and chronic pancreatitis. Our findings showed OCaR1 as a gatekeeper of Ca2+ release that endows NAADP-sensitive secretory granules with an autoregulatory mechanism preventing uncontrolled exocytosis and pancreatic tissue damage.
Volodymyr Tsvilovskyy, Roger Ottenheijm, Ulrich Kriebs, Aline Schütz, Kalliope Nina Diakopoulos, Archana Jha, Wolfgang Bildl, Angela Wirth, Julia Böck, Dawid Jaślan, Irene Ferro, Francisco J. Taberner, Olga Kalinina, Staffan Hildebrand, Ulrich Wissenbach, Petra Weissgerber, Dominik Vogt, Carola Eberhagen, Stefanie Mannebach, Michael Berlin, Vladimir Kuryshev, Dagmar Schumacher, Koenraad Philippaert, Juan E. Camacho-Londoño, Ilka Mathar, Christoph Dieterich, Norbert Klugbauer, Martin Biel, Christian Wahl-Schott, Peter Lipp, Veit Flockerzi, Hans Zischka, Hana Algül, Stefan G. Lechner, Marina Lesina, Christian Grimm, Bernd Fakler, Uwe Schulte, Shmuel Muallem, Marc Freichel
Fibrosis following tissue injury is distinguished from normal repair by the accumulation of pathogenic and apoptosis-resistant myofibroblasts (MFs), which arise primarily by differentiation from resident fibroblasts. Endogenous molecular brakes that promote MF dedifferentiation and clearance during spontaneous resolution of experimental lung fibrosis may provide insights that could inform and improve treatment of progressive pulmonary fibrosis in patients. Mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP1) influences cellular phenotype and fate through precise and timely regulation of MAPK activity within various cell types and tissues, yet its role in lung fibroblasts and pulmonary fibrosis has not been explored. Utilizing gain- and loss-of-function studies, we found that MKP1 promoted lung MF dedifferentiation and restored their sensitivity to apoptosis — effects determined to be mainly dependent upon its dephosphorylation of p38α MAPK (p38α). Fibroblast-specific deletion of MKP1 following peak bleomycin-induced lung fibrosis largely abrogated its subsequent spontaneous resolution. Such resolution was restored by treating these transgenic mice with the p38α inhibitor VX-702. We conclude that MKP1 is a critical antifibrotic brake whose inhibition of pathogenic p38α in lung fibroblasts is necessary for fibrosis resolution following lung injury.
Sean M. Fortier, Natalie M. Walker, Loka R. Penke, Jared D. Baas, Qinxue Shen, Jennifer M. Speth, Steven K. Huang, Rachel L. Zemans, Anton M. Bennett, Marc Peters-Golden
Ca2+-activated BK channels in renal intercalated cells (ICs) mediate luminal flow–induced K+ secretion (FIKS), but how ICs sense increased flow remains uncertain. We examined whether PIEZO1, a mechanosensitive Ca2+-permeable channel expressed in the basolateral membranes of ICs, is required for FIKS. In isolated cortical collecting ducts (CCDs), the mechanosensitive cation-selective channel inhibitor GsMTx4 dampened flow-induced increases in intracellular Ca2+ concentration ([Ca2+]i), whereas the PIEZO1 activator Yoda1 increased [Ca2+]i and BK channel activity. CCDs from mice fed a high-K+ (HK) diet exhibited a greater Yoda1-dependent increase in [Ca2+]i than CCDs from mice fed a control K+ diet. ICs in CCDs isolated from mice with a targeted gene deletion of Piezo1 in ICs (IC-Piezo1-KO) exhibited a blunted [Ca2+]i response to Yoda1 or increased flow, with an associated loss of FIKS in CCDs. Male IC-Piezo1-KO mice selectively exhibited an increased blood [K+] in response to an oral K+ bolus and blunted urinary K+ excretion following a volume challenge. Whole-cell expression of BKα subunit was reduced in ICs of IC-Piezo1-KO mice fed an HK diet. We conclude that PIEZO1 mediates flow-induced basolateral Ca2+ entry into ICs, is upregulated in the CCD in response to an HK diet, and is necessary for FIKS.
Rolando Carrisoza-Gaytan, Stephanie M. Mutchler, Francisco Carattino, Joanne Soong, Marianela G. Dalghi, Peng Wu, WenHui Wang, Gerard Apodaca, Lisa M. Satlin, Thomas R. Kleyman
Translocation Renal Cell Carcinoma (tRCC) most commonly involves an ASPSCR1-TFE3 fusion, but molecular mechanisms remain elusive and animal models are lacking. Here, we show that human ASPSCR1-TFE3 driven by Pax8-Cre (a credentialed ccRCC driver) disrupted nephrogenesis and glomerular development causing neonatal death, whilst the ccRCC failed driver, Sglt2-Cre, induced aggressive tRCC (as well as ASPS) with complete penetrance and short latency. However, in both contexts, ASPSCR1-TFE3 led to characteristic morphological cellular changes, loss of epithelial markers, and an EMT program. Electron microscopy of tRCC tumors showed lysosome expansion and functional studies revealed simultaneous activation of autophagy and mTORC1 pathways. Comparative genomic analyses encompassing an institutional human tRCC cohort (including a hitherto unreported SFPQ-TFEB fusion) and a variety of tumorgraft models (ASPSCR1-TFE3, PRCC-TFE3, SFPQ-TFE3, RBM10-TFE3, and MALAT1-TFEB) disclosed significant convergence in canonical (cell cycle, lysosome and mTORC1) and less established pathways such as Myc, E2F and inflammation (IL6/JAK/STAT3, interferon-γ, TLR signaling, systemic lupus, etc). Therapeutic trials (adjusted for human drug exposures) showed anti-tumor activity of cabozantinib. Overall, this study provides insight into MiT/TFE-driven tumorigenesis including the cell of origin and characterizes diverse mouse models available for research.
Gopinath Prakasam, Akhilesh Mishra, Alana Christie, Jeffrey Miyata, Deyssy Carrillo, Vanina T. Tcheuyap, Hui Ye, Quyen N. Do, Yunguan Wang, Oscar Reig Torras, Ramesh Butti, Hua Zhong, Jeffrey Gagan, Kevin B. Jones, Thomas J. Carroll, Zora Modrusan, Steffen Durinck, Mai-Carmen Requena-Komuro, Noelle S. Williams, Ivan Pedrosa, Tao Wang, Dinesh Rakheja, Payal Kapur, James Brugarolas
Shashwat Tripathi, Hinda Najem, Corey Dussold, Sebastian Pacheco, Jason Miska, Kathleen McCortney, Alicia Steffens, Jordain Walshon, Daniel Winkowski, Michael Cloney, Matthew Ordon, William Gibson, Hanna Kemeny, Mark Youngblood, Rebecca Du, James Mossner, Pavlos Texakalidis, Annelise Sprau, Matthew Tate, Charles David James, Craig M. Horbinski, Nitin R. Wadhwani, Maciej S. Lesniak, Sandi Lam, Ankita Sati, Manish Aghi, Michael DeCuypere, Amy B. Heimberger
Stromal interaction molecule 1 (STIM1) is a Ca2+ sensor located in the sarcoplasmic reticulum (SR) of skeletal muscle where it is best known for its role in store operated Ca2+ entry (SOCE). Genetic syndromes resulting from STIM1 mutations are recognized as a cause of muscle weakness and atrophy. Here, we focus on a gain of function mutation that occurs in humans and mice (STIM1+/D84G mice) where muscles exhibit constitutive SOCE. Unexpectedly, this constitutive SOCE did not affect global Ca2+ transients, SR Ca2+ content or excitation contraction coupling (ECC) and was therefore unlikely to underlie the reduced muscle mass and weakness observed in these mice. Instead, we demonstrate that the presence of D84G STIM1 in the nuclear envelope disrupts nuclear-cytosolic coupling causing severe derangement in nuclear architecture of STIM1+/D84G muscle, DNA damage and altered lamina A associated gene expression. Functionally, we found D84G STIM1 reduced the transfer of Ca2+ from the cytosol to the nucleus in myoblasts resulting in a reduction of [Ca2+]N. Taken together, we propose a novel role for STIM1 in the nuclear envelope that links Ca2+ signaling to nuclear stability in skeletal muscle.
Victoria Bryson, Chaojian Wang, Zirui Zhou, Kavisha Singh, Noah M. Volin, Eda Yildirim, Paul Rosenberg
Mutations in ATP-binding cassette A3 (ABCA3), a phospholipid transporter critical for surfactant homeostasis in pulmonary alveolar type II epithelial cells (AEC2s), are the most common genetic causes of childhood interstitial lung disease (chILD). Treatments for patients with pathological variants of ABCA3 mutations are limited, in part due to a lack of understanding of disease pathogenesis resulting from an inability to access primary AEC2s from affected children. Here, we report the generation of AEC2s from affected patient induced pluripotent stem cells (iPSCs) carrying homozygous versions of multiple ABCA3 mutations. We generated syngeneic CRISPR/Cas9 gene-corrected and uncorrected iPSCs and ABCA3-mutant knockin ABCA3:GFP fusion reporter lines for in vitro disease modeling. We observed an expected decreased capacity for surfactant secretion in ABCA3-mutant iPSC-derived AEC2s (iAEC2s), but we also found an unexpected epithelial-intrinsic aberrant phenotype in mutant iAEC2s, presenting as diminished progenitor potential, increased NFκB signaling, and the production of pro-inflammatory cytokines. The ABCA3:GFP fusion reporter permitted mutant-specific, quantifiable characterization of lamellar body size and ABCA3 protein trafficking, functional features that are perturbed depending on ABCA3 mutation type. Our disease model provides a platform for understanding ABCA3 mutation–mediated mechanisms of alveolar epithelial cell dysfunction that may trigger chILD pathogenesis.
Yuliang L. Sun, Erin E. Hennessey, Hillary Heins, Ping Yang, Carlos Villacorta-Martin, Julian Kwan, Krithi Gopalan, Marianne James, Andrew Emili, F. Sessions Cole, Jennifer A. Wambach, Darrell N. Kotton
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