Disruption of innate defense responses by endoglycosidase HPSE promotes cell survival

Abstract

The drive to withstand environmental stresses and defend against invasion is a universal trait extant in all forms of life. While numerous canonical signaling cascades have been characterized in detail, it remains unclear how these pathways interface to generate coordinated responses to diverse stimuli. To dissect these connections, we follow heparanase (HPSE), a protein best known for its endoglycosidic activity at the extracellular matrix but recently recognized to drive various forms of late stage disease through unknown mechanisms. Using herpes simplex virus-1 (HSV-1) infection as a model cellular perturbation, we demonstrate that HPSE acts beyond its established enzymatic role to restrict multiple forms of cell-intrinsic defense and facilitate host cell reprogramming by the invading pathogen. We reveal that cells devoid of HPSE are innately resistant to infection and counteract viral takeover through multiple amplified defense mechanisms. With a unique grasp of the fundamental processes of transcriptional regulation and cell death, HPSE represents a potent cellular intersection with broad therapeutic potential.

Dissociation of DNA damage sensing by endoglycosidase HPSE

“…HPSE non-enzymatic activity in particular has been implicated in an array of cellular pathways, yet the mechanism of these roles remains unclear (Coombe and Gandhi, 2019;Jayatilleke and Hulett, 2020). Our recent study established that HPSE displays an inhibitory role over type I interferon and downstream responses (Agelidis et al, 2021). Based on results of the current work, HPSE non-enzymatic binding of proteins involved in DNA damage response, particularly MRE11, RAD50, and NBS1, is likely key in the dampening of interferon responses observed in our studies.…”

“…Here and in prior work, we show that HPSE restricts multiple essential cellular defense responses previously linked to one another but not through one factor: type I interferon, cell death, DNA damage, and regulation of the cell cycle (Agelidis et al, 2021). With these related cellular processes in mind, we looked to the multifunctional transcription factor ATM for its potential involvement in the differential regulation by HPSE.…”

“…Given a dearth of biochemical evidence in the literature to explain our recent finding that HPSE acts as a potent regulator of cellular stress responses ( Agelidis et al, 2021 ), we undertook a quantitative proteomics analysis of immunopurified HPSE to investigate the molecular interactions involved ( Figure 1 A). Isolation of myc-tagged HPSE from human corneal epithelial cells and subsequent immunopurification-mass spectrometry (IP-MS) analysis yielded 270 proteins with a ratio of >10 versus isotype antibody pull-down, indicating that HPSE has the capacity for interaction with many more cytoplasmic and nuclear proteins than previously known ( Figures 1 B and S1 ).…”

“…Further promoter motif analysis using the PASTAA algorithm indicates that binding partners of HPSE are likely regulated by several major transcription factors, including CREB1 and the related ATF1, ATF2, and ELK1, known for their roles in driving cell proliferation; E2F1, a key cell cycle regulator; and STAT1, which is heavily implicated in the production and response to type I interferon (Figure S2) (Bommareddy et al, 2018;Ivashkiv and Donlin, 2014;Mayr and Montminy, 2001;Roider et al, 2009). Support for the impact of these transcription factors with respect to HPSE actions also comes from our recent work showing that HPSE restricts multiple innate stress responses (Agelidis et al, 2021). This unique analysis thus draws an initial indirect connection between HPSE and multiple important drivers of cellular proliferation and defense.…”

“…Proteomic samples were processed as previously described with minor alterations (Agelidis et al, 2021;Lapek et al, 2017). Briefly, pelleted beads from immunopurification described above were immersed in 8 M urea + 50 mM HEPES pH 8.5 and were subjected to 5 min water bath sonication and 5 min centrifugation at 18,000 x g to separate proteins from magnetic beads.…”