Updated publication reference for PubMed record(s): 33307037. Objective: Induction of ER stress has been shown to promote NP cell apoptosis and disc degeneration. However, little is known about its regulation by hypoxia and its contribution to extracellular matrix homeostasis. Methods: NP cells were culture under hypoxia (1% O2) and normoxia (21% O2) to assess ER stress status. Tunicamycin and thapsigargin were used to induce canonical ER stress pathways and effects on cell secretome were assessed by proteomic analysis using mass spectrometry. The relevance of these findings to aging and degeneration was investigated by analyzing microarray data of NP tissues from aged mice (GSE134955) and degenerated human discs (GSE70362). Results: NP cells exhibited lower ER stress levels under hypoxia. ER stress inducers tunicamycin and thapsigargin promoted a canonical unfolded protein response. UPR further induced HIF-1 activity under hypoxia. NP cell secretome under ER stress showed an increased secretory pathway with a concomitant decrease in collagens, HAPLN1, and cell adhesion related proteins. Similar to our cell culture studies, NP tissues from aged mice and degenerated human discs presented higher levels of UPR markers and decreased levels of matrix components.