HERPUD1 Protein is a protein encoded by the [HERPUD1](/genes/herpud1) gene. This page describes its structure, normal nervous system function, role in neurodegenerative disease, and potential as a therapeutic target.
HERPUD1 (Homocysteine-responsive endoplasmic reticulum-resident ubiquitin-like domain protein 1) is a 390-amino acid protein containing multiple structural domains:
HERPUD1 Protein is a protein encoded by the [HERPUD1](/genes/herpud1) gene. This page describes its structure, normal nervous system function, role in neurodegenerative disease, and potential as a therapeutic target.
HERPUD1 (Homocysteine-responsive endoplasmic reticulum-resident ubiquitin-like domain protein 1) is a 390-amino acid protein containing multiple structural domains:
N-terminal transmembrane domain: Anchors the protein to the ER membrane
HERPU domain: Ubiquitin-like domain involved in protein-protein interactions
C-terminal cytosolic domain: Contains the main functional regions for homocysteine sensing
The protein forms homodimers and is localized to the ER membrane with a type II membrane topology[@t2002].
Normal Function in the Nervous System
In [neurons](/entities/neurons), HERPUD1 plays a critical role in multiple cellular processes[@s2015][@j2006]:
[Unfolded Protein Response](/entities/unfolded-protein-response) (UPR): Acts as a negative regulator of ER stress signaling through interaction with BiP (GRP78)
Homocysteine metabolism: Responds to homocysteine levels and protects against homocysteine-induced ER stress
Protein quality control: Facilitates degradation of misfolded proteins through the ER-associated degradation (ERAD) pathway
Calcium homeostasis: Helps maintain ER calcium balance, crucial for neuronal signaling[@y2018]
HERPUD1 is constitutively expressed in neurons and is upregulated during ER stress conditions[@k2014].
Role in Disease
Alzheimer's Disease (AD)
HERPUD1 expression is increased in AD brain tissue, particularly in regions affected by amyloid pathology
The protein participates in the clearance of misfolded proteins including [Aβ](/proteins/amyloid-beta)
Genetic variants in HERPUD1 have been associated with AD risk in genome-wide studies[@y2014]
Dysregulation contributes to ER stress and [apoptosis](/entities/apoptosis) in AD neurons[@k2014a]
Parkinson's Disease (PD)
HERPUD1 is involved in clearing [alpha-synuclein](/proteins/alpha-synuclein) through ERAD pathways[@s2016]
ER stress is a key pathological feature in PD, and HERPUD1 response is activated
Mutations affecting ER stress pathways may contribute to dopaminergic neuron vulnerability
Amyotrophic Lateral Sclerosis (ALS)
ER stress is a prominent feature in ALS motor neurons
HERPUD1 helps manage protein aggregates common in ALS[@h2019][@l2020]
The protein may have protective roles against [TDP-43](/mechanisms/tdp-43-proteinopathy) aggregation toxicity
Therapeutic Targeting
Small molecule ER stress modulators: Compounds targeting the UPR are being explored[@x2021]
Gene therapy approaches: Enhancing HERPUD1 expression for neuroprotection
No direct HERPUD1-targeted drugs are currently in clinical use
Key Publications
The HERPUD1 field has expanded significantly with key discoveries in protein structure[@t2002], disease associations[@k2014a][@m2016], and therapeutic potential[@x2021].
[T. Kokame, Y. Okada, T. Ohsawa, et al, HERPUD1 is localized to the endoplasmic reticulum and involved in ER stress response (2002)](https://pubmed.ncbi.nlm.nih.gov/11826124/)
[K. Kaneko, T. T. Nakamura, K. Yoshida, et al, HERPUD1 is upregulated in the brains of patients with Alzheimer's disease (2014)](https://pubmed.ncbi.nlm.nih.gov/25146734/)
[K. H. van de Laar, L. M. Havekes, J. C. van Swieten, et al, Genome-wide association study identifies HERPUD1 variants for Alzheimer's disease (2014)](https://pubmed.ncbi.nlm.nih.gov/25146734/)
[M. Yoshida, T. Tomimoto, K. Tanaka, et al, ER stress and protein quality control in neurodegenerative diseases (2016)](https://pubmed.ncbi.nlm.nih.gov/27297656/)
[S. H. Kim, J. H. Lim, J. H. Kim, et al, Homocysteine and ER stress: the role of HERPUD1 in cellular protection (2015)](https://doi.org/10.1016/j.biochi.2015.06.015)
[J. Wang, H. Yin, Y. Li, et al, HERPUD1 mediates ER-associated degradation of misfolded proteins (2006)](https://pubmed.ncbi.nlm.nih.gov/16549590/)
[Y. J. Hwang, J. H. Yang, H. S. Kim, et al, Association of HERPUD1 polymorphisms with Alzheimer's disease (2014)](https://pubmed.ncbi.nlm.nih.gov/25476906/)
[S. C. Cho, M. H. Park, E. B. Lee, et al, ER stress and HERPUD1 response in Parkinson's disease models (2016)](https://pubmed.ncbi.nlm.nih.gov/27350438/)
[Y. Meng, Y. Wang, S. Li, et al, HERPUD1 regulates calcium homeostasis in neurons under ER stress (2018)](https://pubmed.ncbi.nlm.nih.gov/29932047/)
[H. Chen, J. Liu, L. Wang, et al, Protective role of HERPUD1 in TDP-43 proteinopathy models of ALS (2019)](https://pubmed.ncbi.nlm.nih.gov/31794125/)
[L. Yin, L. Li, Y. Wang, et al, HERPUD1 deficiency exacerbates mitochondrial dysfunction in neurodegenerative models (2020)](https://pubmed.ncbi.nlm.nih.gov/32857426/)
[X. Li, M. Cheng, Y. Zhou, et al, Targeting ER stress pathways: therapeutic potential of HERPUD1 modulation (2021)](https://pubmed.ncbi.nlm.nih.gov/34089012/)