Emerging Concepts in Ion Channel Biophysics

Emerging Concepts in Ion Channel Biophysics

Poster Abstracts

5-POS

Board 5

The T-Type Calcium Channel Cav3.3 (CACNA1I) and Schizophrenia: A Case Study in

What We Can Learn from Human Population Genetics to Understand Structure-Function

Relationships in Ion Channels

David Baez-Nieto

, Andrew Allen, Ayan Goshal, Lingling Yang, Jen Q. Pan.

Stanley Center for Psychiatric Research, Broad Institute of MIT & Harvard, Cambridge, MA,

USA.

Whole-exome sequencing of a large Swedish cohort of schizophrenia patients and controls has

uncovered an enrichment of neuronal genes with disruptive ultra-rare variants (dURVs) that are

associated with schizophrenia risk and converge on specific biological pathways. These dURVs

have an allelic frequency of ~ 1 in 100,000, suggesting that they are likely de novo variants

private to individuals and that may have a deleterious effect on protein function. Therefore,

dURVs are potentially valuable tools to interrogate ion channel structure-function relationships

in the context of human disease. CaV3.3 is implicated in schizophrenia risk by a large cohort

GWAS study. Using the Flp-In/T-REx system we have generated isogenic stable inducible cell

lines for every natural occurring variant in CaV3.3 found in the aforementioned Swedish

Schizophrenia Cohort. Taking advantage of high-throughput automated patch-clamp, we have

characterized more than 60 different variants, of which around 20 are defined as dURVs in this

cohort. We have collected steady-state parameters of activation/inactivation, recovery from

inactivation, and peak current density for all variants, and we have found so far that dURVs

produce stronger functional alterations in the channel properties compared with “common”

variants. The parameters most affected by the dURVs were voltage dependent activation and

peak current density, and voltage dependent inactivation was largely unaffected by most variants.

We have found key dURVs from schizophrenia patients affecting the voltage dependent

activation located in the VSD and gating brake, giving us new insights into how CaV3.3

functions, and how its function may be compromised in schizophrenic patients. Such information

contributes to understanding the role of CaV3.3 in schizophrenia and may shape our strategies to

restore channel function in this context.