Related Experiment Video
Updated: Jul 5, 2025
A Simple and Inexpensive Method for Determining Cold Sensitivity and Adaptation in Mice
Published on: March 17, 2015
Mouse transient receptor potential melastatin 2 (TRPM2) isoform 7 attenuates full-length mouse TRPM2 activity through
Shinichiro Yamamoto1, Naoto Kiyatake1, Akihiro Kaneko1
1Faculty of Pharmaceutical Sciences, Teikyo Heisei University, Tokyo, Japan.
Abstract:
Transient receptor potential melastatin 2 (TRPM2) assembles into tetramers to function as an oxidative stress-sensitive Ca2+ channel at the surface membrane. Limited information is currently available on the 10 protein isoforms of mouse TRPM2 (mTRPM2) identified. This study investigated whether these isoforms function as Ca2+ channels and examined their effects on full-length mTRPM2 activity using the HEK 293 cell exogenous expression system. Only full-length mTRPM2, isoform 1 localized to the surface membrane and was activated by oxidative stress. Isoform 7 was clearly recognized by protein quality control systems and degraded by endoplasmic reticulum-associated degradation after transmembrane proteolysis. In the co-expression system, the activation and expression of full-length mTRPM2 were attenuated by its co-expression with isoform 7, but not with the other isoforms. This decrease in the expression of full-length mTRPM2 was recovered by the proteasomal inhibitor. The present results suggest that isoforms other than isoform 1 did not function as oxidative stress-sensitive channels and also that only isoform 7 attenuated the activation of full-length mTRPM2 by targeting it to endoplasmic reticulum-associated degradation. The present study will provide important information on the functional nature of mTRPM2 isoforms for the elucidation of their roles in physiological and patho-physiological responses in vivo using mouse models.
Insights
Mouse TRPM2 isoforms were studied for their function as calcium channels. Only full-length and isoform 1 localized to the membrane, while isoform 7 degraded full-length TRPM2 via ERAD.
Area of Science:
- Molecular Biology
- Ion Channel Physiology
- Cellular Signaling
Background:
- Transient receptor potential melastatin 2 (TRPM2) forms tetrameric calcium channels sensitive to oxidative stress.
- Ten mouse TRPM2 (mTRPM2) protein isoforms have been identified, but their specific functions remain largely uncharacterized.
- Understanding mTRPM2 isoform function is crucial for elucidating roles in physiological and pathophysiological processes.
Purpose of the Study:
- To investigate the channel function of mTRPM2 protein isoforms.
- To determine the effects of mTRPM2 isoforms on full-length mTRPM2 activity.
- To clarify the cellular mechanisms underlying mTRPM2 isoform interactions.
Main Methods:
- Exogenous expression of mTRPM2 isoforms in HEK 293 cells.
- Co-expression systems to study isoform interactions.
- Assessment of channel localization, oxidative stress sensitivity, and protein degradation pathways (ERAD, proteasomal degradation).
Main Results:
- Only full-length mTRPM2 and isoform 1 localized to the cell surface membrane and responded to oxidative stress.
- mTRPM2 isoform 7 was targeted for degradation via endoplasmic reticulum-associated degradation (ERAD).
- Co-expression with isoform 7, but not other isoforms, attenuated the surface expression and oxidative activation of full-length mTRPM2, an effect reversed by proteasomal inhibitors.
Conclusions:
- mTRPM2 isoforms, except for isoform 1, do not function as oxidative stress-sensitive calcium channels.
- mTRPM2 isoform 7 negatively regulates full-length mTRPM2 function and expression by promoting its degradation through ERAD.
- These findings provide critical insights into the functional diversity of mTRPM2 isoforms and their regulation.
