1
|
Hasegawa H. Temperature-dependent intracellular crystallization of firefly luciferase in mammalian cells is suppressed by D-luciferin and stabilizing inhibitors. Exp Cell Res 2024; 440:114131. [PMID: 38876374 DOI: 10.1016/j.yexcr.2024.114131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 06/10/2024] [Accepted: 06/12/2024] [Indexed: 06/16/2024]
Abstract
Firefly luciferase (Fluc) from Photinus pyralis is one of the most widely used reporter proteins in biomedical research. Despite its widespread use, Fluc's protein phase transition behaviors and phase separation characteristics have not received much attention. Current research uncovers Fluc's intrinsic property to phase separate in mammalian cells upon a simple cell culture temperature change. Specifically, Fluc spontaneously produced needle-shaped crystal-like inclusion bodies upon temperature shift to the hypothermic temperatures ranging from 25 °C to 31 °C. The crystal-like inclusion bodies were not associated with or surrounded by membranous organelles and were likely built from the cytosolic pool of Fluc. Furthermore, the crystal-like inclusion formation was suppressed when cells were cultured in the presence of D-luciferin and its synthetic analog, as well as the benzothiazole family of so-called stabilizing inhibitors. These two classes of compounds inhibited intracellular Fluc crystallization by different modes of action as they had contrasting effects on steady-state luciferase protein accumulation levels. This study suggests that, under substrate insufficient conditions, the excess Fluc phase separates into a crystal-like state that can modulate intracellular soluble enzyme availability and protein turnover rate.
Collapse
Affiliation(s)
- Haruki Hasegawa
- Discovery Protein Science, Department of Large Molecule Discovery and Research Data Science Amgen Inc., South San Francisco, CA 94080, USA.
| |
Collapse
|
2
|
Hasegawa H, Wang S, Kast E, Chou HT, Kaur M, Janlaor T, Mostafavi M, Wang YL, Li P. Understanding the biosynthesis of human IgM SAM-6 through a combinatorial expression of mutant subunits that affect product assembly and secretion. PLoS One 2024; 19:e0291568. [PMID: 38848420 PMCID: PMC11161108 DOI: 10.1371/journal.pone.0291568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 05/06/2024] [Indexed: 06/09/2024] Open
Abstract
Polymeric IgMs are secreted from plasma cells abundantly despite their structural complexity and intricate multimerization steps. To gain insights into IgM's assembly mechanics that underwrite such high-level secretion, we characterized the biosynthetic process of a natural human IgM, SAM-6, using a heterologous HEK293(6E) cell platform that allowed the production of IgMs both in hexameric and pentameric forms in a controlled fashion. By creating a series of mutant subunits that differentially disrupt secretion, folding, and specific inter-chain disulfide bond formation, we assessed their effects on various aspects of IgM biosynthesis in 57 different subunit chain combinations, both in hexameric and pentameric formats. The mutations caused a spectrum of changes in steady-state subcellular subunit distribution, ER-associated inclusion body formation, intracellular subunit detergent solubility, covalent assembly, secreted IgM product quality, and secretion output. Some mutations produced differential effects on product quality depending on whether the mutation was introduced to hexameric IgM or pentameric IgM. Through this systematic combinatorial approach, we consolidate diverse overlapping knowledge on IgM biosynthesis for both hexamers and pentamers, while unexpectedly revealing that the loss of certain inter-chain disulfide bonds, including the one between μHC and λLC, is tolerated in polymeric IgM assembly and secretion. The findings highlight the differential roles of underlying non-covalent protein-protein interactions in hexamers and pentamers when orchestrating the initial subunit interactions and maintaining the polymeric IgM product integrity during ER quality control steps, secretory pathway trafficking, and secretion.
Collapse
Affiliation(s)
- Haruki Hasegawa
- Discovery Protein Science, Department of Large Molecule Discovery and Research Data Science, Amgen Inc., South San Francisco, CA, United States of America
| | - Songyu Wang
- Discovery Protein Science, Department of Large Molecule Discovery and Research Data Science, Amgen Inc., South San Francisco, CA, United States of America
| | - Eddie Kast
- Molecular Analytics, Department of Biologic Therapeutic Discovery, Amgen Inc., South San Francisco, CA, United States of America
| | - Hui-Ting Chou
- Structural Biology, Department of Small Molecule Therapeutic Discovery, Amgen Inc., South San Francisco, CA, United States of America
| | - Mehma Kaur
- Discovery Protein Science, Department of Large Molecule Discovery and Research Data Science, Amgen Inc., South San Francisco, CA, United States of America
| | - Tanakorn Janlaor
- Discovery Protein Science, Department of Large Molecule Discovery and Research Data Science, Amgen Inc., South San Francisco, CA, United States of America
| | - Mina Mostafavi
- Discovery Protein Science, Department of Large Molecule Discovery and Research Data Science, Amgen Inc., South San Francisco, CA, United States of America
| | - Yi-Ling Wang
- Discovery Protein Science, Department of Large Molecule Discovery and Research Data Science, Amgen Inc., South San Francisco, CA, United States of America
| | - Peng Li
- Discovery Protein Science, Department of Large Molecule Discovery and Research Data Science, Amgen Inc., South San Francisco, CA, United States of America
| |
Collapse
|
3
|
Hirata Y, Matsui Y, Wada I, Hosokawa N. ER-to-Golgi trafficking of procollagen III via conventional vesicular and tubular carriers. Mol Biol Cell 2022; 33:ar21. [PMID: 35044867 PMCID: PMC9250382 DOI: 10.1091/mbc.e21-07-0372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Collagen is the major protein component of the extracellular matrix. Synthesis of procollagens starts in the endoplasmic reticulum (ER), and three ⍺ chains form a rigid triple helix 300-400 nm in length. It remains unclear how such a large cargo is transported from the ER to the Golgi apparatus. In this study, to elucidate the intracellular transport of fibril-forming collagens, we fused cysteine-free GFP to the N-telopeptide region of procollagen III (GFP-COL3A1) and analyzed transport by live-cell imaging. We found that the maturation dynamics of procollagen III were largely different from those of network-forming procollagen IV (Matsui et al. 2020). Proline hydroxylation of procollagen III uniquely triggered the formation of intralumenal droplet-like structures similar to events caused by liquid-liquid phase separation, and ER exit sites surrounded large droplets containing chaperones. Procollagen III was transported to the Golgi apparatus via vesicular and tubular carriers containing ERGIC53 and RAB1B; this process required TANGO1 and CUL3, which we previously reported were dispensable for procollagen IV. GFP-COL3A1 and mCherry-⍺1AT were co-transported in the same vesicle. Based on these findings, we propose that shortly after ER exit, enlarged carriers containing procollagen III fuse to ERGIC for transport to the Golgi apparatus by conventional cargo carriers. [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text].
Collapse
Affiliation(s)
- Yukihiro Hirata
- Laboratory of Molecular and Cellular Biology, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8507, Japan
| | - Yuto Matsui
- Laboratory of Molecular and Cellular Biology, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8507, Japan
| | - Ikuo Wada
- Department of Cell Science, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan
| | - Nobuko Hosokawa
- Laboratory of Molecular and Cellular Biology, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8507, Japan
| |
Collapse
|
4
|
Hasegawa H, Wei KY, Thomas M, Li P, Kinderman F, Franey H, Liu L, Jacobsen F. Light chain subunit of a poorly soluble human IgG2λ crystallizes in physiological pH environment both in cellulo and in vitro. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1868:119078. [PMID: 34118277 DOI: 10.1016/j.bbamcr.2021.119078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 05/17/2021] [Accepted: 06/07/2021] [Indexed: 11/28/2022]
Abstract
Prominent inclusion bodies can develop in the endoplasmic reticulum (ER) when overexpressed antibodies possess intrinsically high condensation propensities. These observations suggest that antibodies deemed to show notable solubility problems may reveal such characteristics preemptively in the form of ER-associated inclusion bodies during antibody overexpression. To define the relationships between solubility problems and inclusion body phenotypes, we investigated the biosynthesis of a model human IgG2λ that shows severe opalescence in an acidic formulation buffer yet retains high solubility at physiological pH. Consistent with the pH-dependent solubility characteristics, the model antibody did not induce notable inclusion body in the physiological pH environment of the ER lumen. However, when individual subunit chains of the antibody were expressed separately, the light chain (LC) spontaneously induced notable crystal-like inclusion bodies in the ER. The LC crystallization event was readily reproducible in vitro by simply concentrating the purified LC protein at physiological pH. Two independent structural determinants for the LC crystallization were identified through rational mutagenesis approach by monitoring the effect of amino acid substitutions on intracellular LC crystallogenesis. The effect of mutations on crystallization was also recapitulated in vitro using purified LC proteins. Importantly, when introduced directly into the model antibody, a mutation that prevents the LC crystallization remediated the antibody's solubility problem without compromising the secretory output or antigen binding. These results illustrate that the ER can serve as a "physiological test tube" that not only reports secretory cargo's high condensation propensity at physiological pH, but also provides an orthogonal method that guides antibody engineering strategy.
Collapse
Affiliation(s)
- Haruki Hasegawa
- Department of Therapeutic Discovery, Amgen Inc., South San Francisco, CA 94080, USA.
| | - Kathy Y Wei
- Department of Therapeutic Discovery, Amgen Inc., South San Francisco, CA 94080, USA
| | - Melissa Thomas
- Department of Therapeutic Discovery, Amgen Inc., South San Francisco, CA 94080, USA
| | - Peng Li
- Department of Therapeutic Discovery, Amgen Inc., South San Francisco, CA 94080, USA
| | - Francis Kinderman
- Department of Process Development, Amgen Inc., Thousand Oaks, CA 91320, USA
| | - Heather Franey
- Department of Process Development, Amgen Inc., Thousand Oaks, CA 91320, USA
| | - Ling Liu
- Department of Therapeutic Discovery, Amgen Inc., Thousand Oaks, CA 91320, USA
| | - Frederick Jacobsen
- Department of Therapeutic Discovery, Amgen Inc., Thousand Oaks, CA 91320, USA
| |
Collapse
|
5
|
Simultaneous induction of distinct protein phase separation events in multiple subcellular compartments of a single cell. Exp Cell Res 2019; 379:92-109. [DOI: 10.1016/j.yexcr.2019.03.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Revised: 02/18/2019] [Accepted: 03/05/2019] [Indexed: 01/31/2023]
|
6
|
Hasegawa H, Geng M, Ketchem RR, Liu L, Graham K, Jacobsen F. Intermolecular interactions involving an acidic patch on immunoglobulin variable domain and the γ2 constant region mediate crystalline inclusion body formation in the endoplasmic reticulum. CELLULAR LOGISTICS 2017; 7:e1361499. [PMID: 28944095 DOI: 10.1080/21592799.2017.1361499] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 07/24/2017] [Accepted: 07/25/2017] [Indexed: 10/19/2022]
Abstract
Full-length immunoglobulins (Igs) are widely considered difficult to crystallize because of their large size, N-linked glycosylation, and flexible hinge region. However, numerous cases of intracellular Ig crystallization are reported in plasma cell dyscrasias. What makes some Ig clones more prone to crystallize during biosynthesis as well as the biochemical and cell biological requirements for this cryptic event are poorly understood. To investigate the underlying process of intracellular Ig crystallization we searched for model IgGs that can induce crystalline inclusions during recombinant overexpression. By testing various subunit combinations through mixing and matching of individual subunit chains derived from a panel of human IgG clones, we identified one secretion competent IgG2λ that induced needle-like crystalline inclusions in transfected HEK293 cells. Ig crystallization rarely occurred at steady-state cell growth conditions but was easily induced when ER-to-Golgi transport was pharmacologically blocked. Homology modeling revealed the presence of a prominent negatively-charged patch on the variable domain surface. The patch was composed of eight aspartic acids, of which five were in the heavy chain variable region and three were in the light chain. Crystallization occurred only when the two subunits were co-transfected and the intracellular crystals co-localized with ER resident proteins. Furthermore, subtype switching from IgG2 to IgG1 and stepwise neutralization of the acidic patch independently abrogated Ig crystallization events. The evidence supported that the formation of needle-like crystalline inclusions in the ER was underscored by multivalent intermolecular interactions between the acidic patch and undefined determinants present on the γ2 subunit constant region.
Collapse
Affiliation(s)
- Haruki Hasegawa
- Department of Therapeutic Discovery, Amgen Inc., South San Francisco, CA, USA
| | - Mei Geng
- Department of Therapeutic Discovery, Amgen Inc., South San Francisco, CA, USA
| | - Randal R Ketchem
- Department of Therapeutic Discovery, Amgen Inc., South San Francisco, CA, USA
| | - Ling Liu
- Department of Therapeutic Discovery, Amgen Inc., Thousand Oaks, CA, USA
| | - Kevin Graham
- Department of Therapeutic Discovery, Amgen Inc., Thousand Oaks, CA, USA
| | | |
Collapse
|
7
|
Hasegawa H, Hsu A, Tinberg CE, Siegler KE, Nazarian AA, Tsai MM. Single amino acid substitution in LC-CDR1 induces Russell body phenotype that attenuates cellular protein synthesis through eIF2α phosphorylation and thereby downregulates IgG secretion despite operational secretory pathway traffic. MAbs 2017; 9:854-873. [PMID: 28379093 DOI: 10.1080/19420862.2017.1314875] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Amino acid sequence differences in the variable region of immunoglobulin (Ig) cause wide variations in secretion outputs. To address how a primary sequence difference comes to modulate Ig secretion, we investigated the biosynthetic process of 2 human IgG2κ monoclonal antibodies (mAbs) that differ only by one amino acid in the light chain complementarity-determining region 1 while showing ∼20-fold variance in secretion titer. Although poorly secreted, the lower-secreting mAb of the 2 was by no means defective in terms of its folding stability, antigen binding, and in vitro biologic activity. However, upon overexpression in HEK293 cells, the low-secreting mAb revealed a high propensity to aggregate into enlarged globular structures called Russell bodies (RBs) in the endoplasmic reticulum. While Golgi morphology was affected by the formation of RBs, secretory pathway membrane traffic remained operational in those cells. Importantly, cellular protein synthesis was severely suppressed in RB-positive cells through the phosphorylation of eIF2α. PERK-dependent signaling was implicated in this event, given the upregulation and nuclear accumulation of downstream effectors such as ATF4 and CHOP. These findings illustrated that the underlining process of poor Ig secretion in RB-positive cells was due to downregulation of Ig synthesis instead of a disruption or blockade of secretory pathway trafficking. Therefore, RB formation signifies an end of active Ig production at the protein translation level. Consequently, depending on how soon and how severely an antibody-expressing cell develops the RB phenotype, the productive window of Ig secretion can vary widely among the cells expressing different mAbs.
Collapse
Affiliation(s)
- Haruki Hasegawa
- a Department of Therapeutic Discovery , Amgen Inc. , South San Francisco , CA , USA
| | - Ann Hsu
- b Department of Therapeutic Discovery , Amgen Inc. , Thousand Oaks , CA , USA
| | - Christine E Tinberg
- a Department of Therapeutic Discovery , Amgen Inc. , South San Francisco , CA , USA
| | - Karen E Siegler
- c Department of Cardiometabolic Disorders , Amgen Inc. , South San Francisco , CA , USA
| | - Aaron A Nazarian
- b Department of Therapeutic Discovery , Amgen Inc. , Thousand Oaks , CA , USA
| | - Mei-Mei Tsai
- b Department of Therapeutic Discovery , Amgen Inc. , Thousand Oaks , CA , USA
| |
Collapse
|