Subcellular dynamics and functional activity of the cleaved intracellular domain of the Na+ channel β1 subunit

Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved..

The voltage-gated Na+ channel β1 subunit, encoded by SCN1B, regulates cell surface expression and gating of α subunits and participates in cell adhesion. β1 is cleaved by α/β and γ-secretases, releasing an extracellular domain and intracellular domain (ICD), respectively. Abnormal SCN1B expression/function is linked to pathologies including epilepsy, cardiac arrhythmia, and cancer. In this study, we sought to determine the effect of secretase cleavage on β1 function in breast cancer cells. Using a series of GFP-tagged β1 constructs, we show that β1-GFP is mainly retained intracellularly, particularly in the endoplasmic reticulum and endolysosomal pathway, and accumulates in the nucleus. Reduction in endosomal β1-GFP levels occurred following γ-secretase inhibition, implicating endosomes and/or the preceding plasma membrane as important sites for secretase processing. Using live-cell imaging, we also report β1ICD-GFP accumulation in the nucleus. Furthermore, β1-GFP and β1ICD-GFP both increased Na+ current, whereas β1STOP-GFP, which lacks the ICD, did not, thus highlighting that the β1-ICD is necessary and sufficient to increase Na+ current measured at the plasma membrane. Importantly, although the endogenous Na+ current expressed in MDA-MB-231 cells is tetrodotoxin (TTX)-resistant (carried by Nav1.5), the Na+ current increased by β1-GFP or β1ICD-GFP was TTX-sensitive. Finally, we found β1-GFP increased mRNA levels of the TTX-sensitive α subunits SCN1A/Nav1.1 and SCN9A/Nav1.7. Taken together, this work suggests that the β1-ICD is a critical regulator of α subunit function in cancer cells. Our data further highlight that γ-secretase may play a key role in regulating β1 function in breast cancer.

Medienart:

E-Artikel

Erscheinungsjahr:

2022

Erschienen:

2022

Enthalten in:

Zur Gesamtaufnahme - volume:298

Enthalten in:

The Journal of biological chemistry - 298(2022), 8 vom: 05. Aug., Seite 102174

Sprache:

Englisch

Beteiligte Personen:

Haworth, Alexander S [VerfasserIn]
Hodges, Samantha L [VerfasserIn]
Capatina, Alina L [VerfasserIn]
Isom, Lori L [VerfasserIn]
Baumann, Christoph G [VerfasserIn]
Brackenbury, William J [VerfasserIn]

Links:

Volltext

Themen:

β secretase
γ-secretase
4368-28-9
9NEZ333N27
Amyloid Precursor Protein Secretases
EC 3.4.-
Journal Article
Membrane trafficking
NAV1.7 Voltage-Gated Sodium Channel
Proteolysis
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
SCN9A protein, human
Sodium
Sodium Channels
Tetrodotoxin
Voltage-Gated Sodium Channel beta-1 Subunit
Voltage-gated sodium channel

Anmerkungen:

Date Completed 08.09.2022

Date Revised 09.12.2022

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1016/j.jbc.2022.102174

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM342733745