Cell-type specific effects of PERK-B associated single nucleotide polymorphisms in HAND pathology



Shivesh Ghura

Shivsh Ghura1, Xinglong Shi2, Sarah Bond3, Cagla Akay-Espinoza2, Kelly, L Jordan-Sciutto2
1Systemics Pharmacology and Translational Therapeutics, University of Pennsylvania; 2Basic and Translational Sciences, University of Pennsylvania; 3Biochemistry and Biophysics, University of Pennsylvania 

 

Introduction

Antiretrovirals have increased the life expectancy of people living with HIV, however about 50% of them present with a spectrum of neurocognitive impairments termed HIV-associated neurocognitive disorder (HAND). At the cellular level, increased ER stress leading to potentially maladaptive unfolded protein response (UPR) activation has been reported. A downstream event in UPR is the activation of ER stress sensor PERK, which has been implicated in neurodegenerative disorders including HAND. The gene encoding PERK is known to contain three non-synonymous SNPs in 31% of the general population. These SNPs are genetically linked forming haplotype B (PERK-B) distinct from the more common haplotype (61%), PERK-A. Notably, PERK-B is associated with increased risk for progressive supranuclear palsy. We have found that PERK-B associates with worse cognitive global deficit score in HAND patients. Current literature on the impact of PERK-B SNPs on its activity remain contradictory. We hypothesize that PERK-B has a higher kinase activity, potentially predisposing individuals to neuronal dysfunction.

Methods

We have developed a novel mouse model expressing PERK-B associated exonic SNPs, called the PERK-B mice. These mice are great resources for primary neuron, mixed neuroglia and macrophage cultures. Thapsigargin, a UPR activator or PERK-specific activator are used in vitro to ascertain differences in PERK activation in different cell types.

Results

In vitro and in vivo data from this model suggest that PERK-B activity is increased in myeloid lineage cells, specifically macrophages, while no difference in PERK activation are observed between PERK-A and PERK-B in neurons. Kinase assay using purified PERK-A or PERK-B suggests that PERK-B associated SNPs increase its kinase activity. Further, we see evidence of increased kinase activity in liver and pancreas.

Conclusion

These findings suggest PERK-B SNPs modulate cell type-specific mechanisms underlying HAND pathology.