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Role of FAM134 paralogues in endoplasmic reticulum remodeling, ER‐phagy, and Collagen quality control
Author(s) -
Reggio Alessio,
Buonomo Viviana,
Berkane Rayene,
Bhaskara Ramachandra M,
Tellechea Mariana,
Peluso Ivana,
Polishchuk Elena,
Di Lorenzo Giorgia,
Cirillo Carmine,
Esposito Marianna,
Hussain Adeela,
Huebner Antje K,
Hübner Christian A,
Settembre Carmine,
Hummer Gerhard,
Grumati Paolo,
Stolz Alexandra
Publication year - 2021
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.15252/embr.202052289
Subject(s) - endoplasmic reticulum , microbiology and biotechnology , autophagy , unfolded protein response , biology , chemistry , genetics , apoptosis
Abstract Degradation of the endoplasmic reticulum (ER) via selective autophagy (ER‐phagy) is vital for cellular homeostasis. We identify FAM134A/RETREG2 and FAM134C/RETREG3 as ER‐phagy receptors, which predominantly exist in an inactive state under basal conditions. Upon autophagy induction and ER stress signal, they can induce significant ER fragmentation and subsequent lysosomal degradation. FAM134A, FAM134B/RETREG1, and FAM134C are essential for maintaining ER morphology in a LC3‐interacting region (LIR)‐dependent manner. Overexpression of any FAM134 paralogue has the capacity to significantly augment the general ER‐phagy flux upon starvation or ER‐stress. Global proteomic analysis of FAM134 overexpressing and knockout cell lines reveals several protein clusters that are distinctly regulated by each of the FAM134 paralogues as well as a cluster of commonly regulated ER‐resident proteins. Utilizing pro‐Collagen I, as a shared ER‐phagy substrate, we observe that FAM134A acts in a LIR‐independent manner and compensates for the loss of FAM134B and FAM134C, respectively. FAM134C instead is unable to compensate for the loss of its paralogues. Taken together, our data show that FAM134 paralogues contribute to common and unique ER‐phagy pathways.