# Decoding Doublecortin function in key organizational pathways of the cortex

> **NIH NIH F31** · UNIVERSITY OF CALIFORNIA, SAN FRANCISCO · 2020 · $39,120

## Abstract

PROJECT SUMMARY/ABSTRACT
Normal brain function requires proper establishment of cerebral cortical layering during development. A central
aspect of development of the cerebral cortex layers is the migration of newly-born neurons to their specific
destination in one of the six cortical layers. Neuronal migration involves orchestrated changes to the cytoskeleton
driven in part by dynamic changes to microtubules with the aid of microtubule associating proteins (MAPs).
Doublecortin (DCX) is a MAP that is highly expressed in immature, migrating neurons. DCX dysfunction has
been linked to lissencephaly, a malformation characterized by a lack of gyri in the cortex, and subcortical band
heterotropia (SBH) or a "double cortex". However, the role of DCX in neuronal migration is not understood.
Studies in mouse models have only investigated the effects of a complete knockout (KO) of Dcx, which resulted
in a minor hippocampal lamination phenotype but no phenotype in the cortex as seen in humans. This example
has been cited to support the claim that mice may be poor models to study complex disorders of human cortical
development and disease, due to species differences. However, documented disease-causing human DCX
mutations involve missense mutation in one of DCX's microtubule binding domains, which does not remove DCX
function entirely. In this regard, my preliminary data indicate that Dcx protein with a human missense mutation
is robustly expressed. I thus propose to determine whether the lack of a cortical phenotype in mice is due to
species differences or due to compensatory mechanisms after complete Dcx ablation. Specifically, I will
introduce a human disease-causing DCX mutation (T203R) into the endogenous mouse Dcx locus. This will
enable direct analysis of how a patient-specific mutation affects the function of doublecortin as a MAP during
neuronal migration in the cortex. Conversely, I will completely ablate DCX or introduce the DCX T203R mutation
into the endogenous DCX locus in human induced pluripotent stem cells (hiPSCs), to directly address the limited
experimental studies performed on a human genetic background, and to complement the proposed studies of
endogenous Dcx in the mouse. I will use these hiPSC lines to generate neurons and cerebral organoids, in order
to define the extent to which complete DCX ablation or the human DCX T203R mutation causes impaired
neuronal migration in a human experimental context. The proposed studies are important because the impact of
complete DCX inactivation versus patient missense mutations has not been evaluated in isogenic human lines
or in a three-dimensional human tissue context. Together, this project is expected to yield fundamental insights
into a key organizational event in cortical development, as well as to establish approaches to improve studies of
mutations associated with human developmental disorders more broadly.

## Key facts

- **NIH application ID:** 10069168
- **Project number:** 1F31NS118981-01
- **Recipient organization:** UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
- **Principal Investigator:** Beatriz Alvarado
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $39,120
- **Award type:** 1
- **Project period:** 2020-09-01 → 2023-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10069168

## Citation

> US National Institutes of Health, RePORTER application 10069168, Decoding Doublecortin function in key organizational pathways of the cortex (1F31NS118981-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10069168. Licensed CC0.

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