Armet/Manf and Creld2 are components of a specialized ER stress response provoked by inappropriate formation of disulphide bonds: implications for genetic skeletal diseases

Abstract

Mutant matrilin-3 (V194D) forms non-native disulphide bonded aggregates in the rER of chondrocytes from cell and mouse models of multiple epiphyseal dysplasia (MED). Intracellular retention of mutant matrilin-3 causes endoplasmic reticulum (ER) stress and induces an unfolded protein response (UPR) including the upregulation of two genes recently implicated in ER stress: Armet and Creld2. Nothing is known about the role of Armet and Creld2 in human genetic diseases. In this study, we used a variety of cell and mouse models of chondrodysplasia to determine the genotype-specific expression profiles of Armet and Creld2. We also studied their interactions with various mutant proteins and investigated their potential roles as protein disulphide isomerases (PDIs). Armet and Creld2 were up-regulated in cell and/or mouse models of chondrodysplasias caused by mutations in Matn3 and Col10a1, but not Comp. Intriguingly, both Armet and Creld2 were also secreted into the ECM of these disease models following ER stress. Armet and Creld2 interacted with mutant matrilin-3, but not with COMP, thereby validating the genotype-specific expression. Substrate-trapping experiments confirmed Creld2 processed PDI-like activity, thus identifying a putative functional role. Finally, alanine substitution of the two terminal cysteine residues from the A-domain of V194D matrilin-3 prevented aggregation, promoted mutant protein secretion and reduced the levels of Armet and Creld2 in a cell culture model. We demonstrate that Armet and Creld2 are genotype-specific ER stress response proteins with substrate specificities, and that aggregation of mutant matrilin-3 is a key disease trigger in MED that could be exploited as a potential therapeutic target.

Role of Endoplasmic reticulum apoptotic pathway in testicular Sertoli cells injury induced by Carbon disulfide

“…CHOP plays an inducer role in cell death. The expression of CHOP is also strongly enhanced in ER-induced apoptosis in a variety of cell types (Gotoh et al, 2002;Tsukano et al, 2010;Hartley et al, 2013). Therefore, the increase of mRNA and protein expression levels of GRP78 and CHOP in our study supported the involvement of ER apoptotic pathway in CS 2 induced Sertoli cell apoptosis.…”

Characterization of the Role of MANF in Regulating the Secretion of CRELD2

“…In the last few years, it has been reported that the expression of CRELD2 and MANF are elevated in several physiological conditions, which are not restricted to the central nervous system. 23,[37][38][39] Therefore, further characterization of MANF and CRELD2 inside and outside cells under pathophysiological conditions may give new insights into the onset and progression of ER stress-related diseases. Fig.…”

Mesencephalic astrocyte-derived neurotrophic factor (MANF), a new player in endoplasmic reticulum diseases: structure, biology, and therapeutic roles

“…In vitro , MANF expression is upregulated in cell lines derived from bone tissue (U2OS), kidneys (HEK293), neuroblastoma (SH-SY5Y) and embryo fibroblasts (NIH 3T3) in response to ER stress triggered by tunicamycin (TM), thapsigargin (TG), and lactatystin 26, 33 . In vivo , MANF expression is induced in chondrocytes following ER retention of the mutant cartilage extracellular matrix protein in mouse knock-in models of chondrodysplasia caused by matrilin-3 or type × collagen mutations 34 , in pancreatic β cells following misfolding of mutant proinsulin in Akita mouse model carrying an insulin C96Y mutation 26 , and in synoviocytes following inflammation mediated-ER stress in a rabbit antigen-induced arthritis model 29 . MANF expression is also increased in response to ischemia-induced ER stress both in vitro and in vivo 32, 33, 35–37 .…”