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

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.

Medienart:

E-Artikel

Erscheinungsjahr:

2017

Erschienen:

2017

Enthalten in:

Zur Gesamtaufnahme - volume:9

Enthalten in:

mAbs - 9(2017), 5 vom: 17. Juli, Seite 854-873

Sprache:

Englisch

Beteiligte Personen:

Hasegawa, Haruki [VerfasserIn]
Hsu, Ann [VerfasserIn]
Tinberg, Christine E [VerfasserIn]
Siegler, Karen E [VerfasserIn]
Nazarian, Aaron A [VerfasserIn]
Tsai, Mei-Mei [VerfasserIn]

Links:

Volltext

Themen:

Complementarity Determining Regions
EIF2α
Endoplasmic reticulum
Eukaryotic Initiation Factor-2
Immunoglobulin
Immunoglobulin G
Journal Article
Protein translation
Russell body
Single amino acid substitution

Anmerkungen:

Date Completed 09.04.2018

Date Revised 13.11.2018

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1080/19420862.2017.1314875

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM27066999X