Open Access

REVIEW

ER exit pathways and the control of proteostasis: Crucial role of the UPR, COPII, and ER-phagy in the secretory pathway

GIUSEPPINA AMODIO¹, VALENTINA PAGLIARA¹, PAOLO REMONDELLI^1,*, ORNELLA MOLTEDO²

1 Dipartimento di Medicina, Chirurgia e Odontoiatria “Scuola Medica Salernitana”, Università degli Studi di Salerno, Baronissi, 84034, Italy
2 Dipartimento di Farmacia, Università degli Studi di Salerno, Fisciano, 84084, Italy

* Address correspondence to: Paolo Remondelli,

BIOCELL 2022, 46(5), 1131-1137. https://doi.org/10.32604/biocell.2022.018638

Received 07 August 2021; Accepted 13 October 2021; Issue published 06 January 2022

Abstract

The endoplasmic reticulum (ER) is the site of entry of all proteins that function in the secretory pathway including the extracellular environment. Because it controls the folding of newly synthesized secretory proteins, the ER is indispensable for the maintenance of proteostasis in the secretory pathway. Within the ER and, in part, in post-ER compartments, the quality control of protein folding is under the regulation of the unfolded protein response (UPR) pathways. The UPR strategy is to enhance protein folding, increase the ER degradation pathway of misfolded proteins, and allow the exit from the ER of only correctly folded proteins. The latter is controlled by the multimeric complex COPII, which also provides some of the components for ER-phagy the only route for the disposal of protein aggregates. In this overview, we wish to contribute to the introduction of new perspectives in the study of the mechanisms underlying the control of proteostasis within the secretory pathway.

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