Protein associated with ovarian cancer exacerbates neurodegeneration in Alzheimer’s

Summary: OCIAD1, a protein commonly associated with ovarian cancer, contributes to neurodegeneration in Alzheimer’s disease by impairing mitochondrial function, leading to synaptic damage and neural vulnerability.

Source: Houston Methodist

Houston Methodist scientists identified a protein found in ovarian cancer that may contribute to declining brain function and Alzheimer’s disease, by combining computational methods and lab research.

“Our finding suggests another known protein may be coming into play here, which could help us identify a new therapeutic target one day,” said Stephen T.C. Wong, Ph.D., lead author and Associate Director of Bioinformatics and Biostatistics Cores at Houston Methodist Cancer Center. “These findings may suggest a different role of the protein amyloid beta in neurodegeneration. Many Alzheimer’s researchers have focused on amyloid beta alone, or connections between amyloid beta and another protein, tau.”

In a study published online in the journal EBiomedicine, Wong and his team at the Ting Tsung and Wei Fong Chao Center for BRAIN of Houston Methodist, reported on a new role of OCIAD1 (ovarian cancer immune-reactive antigen domain containing 1). Originally discovered for its effect on ovarian cancer metastasis and stem cell metabolisms, Wong’s group found the OCIAD1 protein in human brain cells–and determined it impairs neurons and damages synapses in the brain, contributing to neurodegeneration in Alzheimer’s disease.

“Our research addresses a fundamental question of Alzheimer’s disease–how, or if, amyloid beta accumulation that can be seen up to two decades prior to brain function decline is involved in progressive neurodegeneration,” said Wong, who is John S Dunn Sr. presidential distinguished chair in biomedical engineering and professor of computer science and bioengineering in oncology at Houston Methodist. “Examining factors that contribute to the progressive decline in people with Alzheimer’s will help us develop diagnostic biomarkers and new therapeutics.”

The scientists culled through archived bioinformatics data of brain tissue from deceased Alzheimer’s patients, as well as mouse models by blending computational methods with laboratory research. They determined that OCIAD1 plays a role in the disease’s progressive neurodegeneration by impairing mitochondria function. Known as the powerhouse of cells, damage to mitochondria results in the trickle-down cell death effect in the brain leading to neuron damage.

“We applied a system biology strategy to see if we could find a different mechanism of neurodegeneration in Alzheimer’s disease. We identified OCIAD1 as a new neurodegeneration-relevant factor, predicted its function, and demonstrated it mediates the long-term impact of amyloid beta on cells and synaptic damages by impairing mitochondria function,” said Xuping Li, Ph.D., co-corresponding author and an instructor in Wong’s group.

This shows neurons
In the brain of mice with Alzheimer’s, areas near amyloid plaques (A) appear with fewer neural networks (B), dying neurons (C) and higher OCIAD1 (D). In cultured neuronal cells, the OCIAD1 proteins (E) appear in the mitochondria (F). Image is credited to Houston Methodist.

Alzheimer’s research has traditionally focused on a few major themes – the role of the amyloid protein on neuronal loss and how this toxic protein causes injury by interacting with tau. More recently, however, other research considers amyloid beta a bystander and questions whether it causes neuronal degeneration at all.

Wong’s group next intends to examine whether OCIAD1 plays a role in the interplay between two known changes in Alzheimer’s – amyloid beta and tau aggregates. If so, additional research would focus on the potential of OCIAD1 as a biomarker or therapeutic target.

The epidemic of Alzheimer’s, a disease affecting more than 5.8 million Americans, is expected to increase as the aging population lives longer. According to the Alzheimer’s Association and the Center for Disease Control and Prevention, Alzheimer’s is the most expensive disease in the United States, costing an estimated $290 billion in 2019.

Other researchers collaborating on this paper include Xuping Li, Lin Wang, Matthew Cykowski, Tiancheng He, Timothy Liu, Joshua Chakranarayan, Andreana Rivera, Hong Zhao and Suzanne Powell (Houston Methodist Hospital and Houston Methodist Research Institute), and Weiming Xia (Boston University School of Medicine and Boston VA Medical Center).

Funding: This study was supported in part by grants from the Ting Tsung & Wei Fong Chao Foundation, John S Dunn Research Foundation, Cure Alzheimer’s Fund, and the National Institutes of Health (R01AG057635 and R01AG028928).

About this neurology research article

Source:
Houston Methodist
Media Contacts:
Gale Smith – Houston Methodist
Image Source:
The image is credited to Houston Methodist.

Original Research: Open access
“OCIAD1 contributes to neurodegeneration in Alzheimer’s disease by inducing mitochondria dysfunction, neuronal vulnerability and synaptic damages”. Stephen T.C. Wong et al.
EBioMedicine doi:10.1016/j.ebiom.2019.11.030.

Abstract

OCIAD1 contributes to neurodegeneration in Alzheimer’s disease by inducing mitochondria dysfunction, neuronal vulnerability and synaptic damages

Background
Hyperamyloidosis in the brain is known as the earliest neuropathological change and a unique etiological factor in Alzheimer’s disease (AD), while progressive neurodegeneration in certain vulnerable brain regions forms the basis of clinical syndromes. It is not clear how early hyperamyloidosis is implicated in progressive neurodegeneration and what factors contribute to the selective brain vulnerability in AD.

Methods
Bioinformatics and experimental neurobiology methods were integrated to identify novel factors involved in the hyperamyloidosis-induced brain vulnerability in AD. We first examined neurodegeneration-specific gene signatures from sporadic AD patients and synaptic protein changes in young transgenic AD mice. Then, we systematically assessed the association of a top candidate gene with AD and investigated its mechanistic role in neurodegeneration.

Findings
We identified the ovary-orientated protein OCIAD1 (Ovarian-Carcinoma-Immunoreactive-Antigen-Domain-Containing-1) as a neurodegeneration-associated factor for AD. Higher levels of OCIAD1, found in vulnerable brain areas and dystrophic neurites, were correlated with disease severity. Multiple early AD pathological events, particularly Aβ/GSK-3β signaling, elevate OCIAD1, which in turn interacts with BCL-2 to impair mitochondrial function and facilitates mitochondria-associated neuronal injury. Notably, elevated OCIAD1 by Aβ increases cell susceptibility to other AD pathological challenges.

Interpretation
Our findings suggest that OCIAD1 contributes to neurodegeneration in AD by impairing mitochondria function, and subsequently leading to neuronal vulnerability, and synaptic damages.

Funding
Ting Tsung & Wei Fong Chao Foundation, John S Dunn Research Foundation, Cure Alzheimer’s Fund, and NIH R01AG057635 to STCW.

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