Targeted disruption of Kv2.1-VAPA association provides neuroprotection against ischemic stroke in mice by declustering Kv2.1 channels

Abstract

<jats:p>Kv2.1 channels mediate cell death–enabling loss of cytosolic potassium in neurons following plasma membrane insertion at somatodendritic clusters. Overexpression of the carboxyl terminus (CT) of the cognate channel Kv2.2 is neuroprotective by disrupting Kv2.1 surface clusters. Here, we define a seven–amino acid declustering domain within Kv2.2 CT (DP-2) and demonstrate its neuroprotective efficacy in a murine ischemia-reperfusion model. TAT-DP-2, a membrane-permeable derivative, induces Kv2.1 surface cluster dispersal, prevents post-injurious pro-apoptotic potassium current enhancement, and is neuroprotective in vitro by disrupting the association of Kv2.1 with VAPA. TAT-DP-2 also induces Kv2.1 cluster dispersal in vivo in mice, reducing infarct size and improving long-term neurological function following stroke. We suggest that TAT-DP-2 induces Kv2.1 declustering by disrupting Kv2.1-VAPA association and scaffolding sites required for the membrane insertion of Kv2.1 channels following injury. We present the first evidence of targeted disruption of Kv2.1-VAPA association as a neuroprotective strategy following brain ischemia.</jats:p>

The Redox Biology of Excitotoxic Processes: The NMDA Receptor, TOPA Quinone, and the Oxidative Liberation of Intracellular Zinc

“…This has been, admittedly, a very difficult problem, to which large amounts of financial resources and numerous careers have been devoted. Our own recent work points to new therapeutic avenues to pursue, targeting Kv2.1-mediated potassium efflux in cell death processes ( Yeh et al, 2017 , 2019 ; Schulien et al, 2020 ). Although ameliorating excitotoxic injury and clinical disability has been very challenging, a better appreciation of critical mechanisms can only improve the potential to succeed in addressing this important unmet medical need.…”

ER-PM Contact Sites – SNARING Actors in Emerging Functions

“…Interestingly, disrupting the phosphorylation-dependent interaction between Kv2.1 and VAP-A ( Kirmiz et al, 2019 ) is neuroprotective and prevents pro-apoptotic K + entry upon ischaemic injury ( Schulien et al, 2020 ). It is particularly interesting that Kv1.1 and Kv2.1 channels were also found to interact with Stx1 ( Fili et al, 2001 ) and SNAP-25 ( MacDonald et al, 2002 ; Leung et al, 2003 ).…”

Lessons from Recent Advances in Ischemic Stroke Management and Targeting Kv2.1 for Neuroprotection

“…However, side effects associated with broad-spectrum potassium channel blockers, such as tetraethylammonium bromide [ 70 ], have been a crux in the development of a feasible therapy. As a significant advantage in our strategy, many aspects of the molecular events in the Kv2.1 cell death cascade can be targeted for neuroprotection without affecting Kv2.1 basal currents [ 69 , 71 , 72 , 73 ]. We present our two most developed strategies below, as illustrated in Figure 2 C,D.…”

“…Studies based on this work have demonstrated that overexpression of the C-terminus of the cognate channel, Kv2.2, induces dispersal of these channel clusters [ 82 ], preventing potassium efflux following oxidative injury, and providing neuroprotection in vitro [ 83 ]. In a recent study, we exploited knowledge of this proapoptotic Kv2.1 surface insertion mechanism to validate the targeted-disruption of Kv2.1-VAPA association and cluster dispersal as a neuroprotective strategy [ 73 ].…”

“…We showed that this peptide, importantly, induces rapid disruption of Kv2.1 channel clusters in mice in vivo following intraperitoneal injection and demonstrated its neuroprotective efficacy in the context of ischemic stroke ( Figure 2 D). We showed that when administered by intraperitoneal injection following MCAO with subsequent reperfusion, TAT-DP-2 reduces total infarct volume at 24 h and provides long-term preservation of neurological motor function in mice over a 42-day period [ 73 ].…”