The N-Terminal Fragment of Urine Titin Is Not a Product of Degradation by Calpain 3.

ABSTRACT:

Introduction

A 20 kDa fragment at the N-terminus of titin is highly excreted in the urine of patients with Duchenne muscular dystrophy (DMD), making urine titin a prominent biomarker for muscle breakdown. This N-terminal fragment is presumed to be a product of degradation by a protein-degrading enzyme, calpain 3; however, whether calpain 3 is required remains unclear. We aimed to determine whether urine titin elevation occurs in the absence of calpain 3.

Methods

We measured urine titin by ELISA in two genetically confirmed limb-girdle muscular dystrophy type R1(LGMDR1) patients, 11 other LGMD patients, and five healthy controls. Five Capn3-/- and nine wild-type mice were also examined.

Results

Urine titin in LGMDR1 patients was ~100-fold higher than in controls (media

SUBMITTER: Nambu Y 

PROVIDER: S-EPMC11799402 | biostudies-literature | 2025 Mar

REPOSITORIES: biostudies-literature