# Elucidating functions of the gamma-protocadherins in CNS development

> **NIH NIH R01** · UNIVERSITY OF IOWA · 2020 · $377,705

## Abstract

Growth of a complex dendrite arbor is a prerequisite for neural circuit formation, and reduced arbor complexity
in the cortex is a consistent finding in neurodevelopmental/neuropsychiatric disorders. For future therapeutic
approaches to be conceivable, there is a critical need to elucidate the molecular mechanisms that regulate
dendrite arborization. The γ-Protocadherins (γ-Pcdhs), a family of 22 cell adhesion molecules encoded by the
Pcdhg gene cluster, are required for normal cortical dendrite arborization; the mechanisms through which their
diverse isoforms act are, however, poorly understood. The long-term goal is to identify molecular mechanisms
that control neural circuit formation. The objective of this renewal application is to elucidate how both isoform
diversity and common signaling mechanisms contribute to γ-Pcdh regulation of dendrite arborization. The
central hypothesis is that γ-Pcdhs regulate arborization through: 1) diverse homophilic cell-cell interactions; 2)
isoform-specific signaling via unique variable cytoplasmic domains (VCDs); and 3) shared signaling via a
common C-terminal motif. Three Aims are proposed, each premised on published work from the current grant
period, and each utilizing novel Pcdhg alleles generated through CRISPR/Cas9 genome editing. Aim 1:
Establish the importance of a shared γ-Pcdh C-terminal motif in dendrite arborization in vivo. PKC phosphory-
lation of a serine within a lysine-rich C-terminal motif abrogates its ability to bind phospholipids, and prevents γ-
Pcdhs from inhibiting FAK and promoting dendrite arborization in vitro. To address the importance of this in
vivo, 2 new mouse lines will be examined for arborization, γ-Pcdh protein stability, and FAK regulation:
PcdhgS/A, in which the serine is mutated to an alanine, preventing phosphorylation; and PcdhgCTD, in which a
premature stop codon results in proteins lacking the motif. Aim 2: Identify isoform-specific mechanisms through
which the γ-Pcdh-C3 VCD regulates dendrite arborization. The VCD of the γ-Pcdh-C3 isoform uniquely inhibits
Wnt signaling by binding to Axin1, a known regulator of dendrite arborization. Using in utero electroporation,
Axin1 knockdown, and a novel PcdhgC3KO single-isoform knockout mouse, a distinct role for C3 in dendrite
arborization will be ascertained. Aim 3: Ascertain the importance of γ-Pcdh isoform diversity for dendrite
arborization and behavior. It's unknown whether isoform diversity generated by the endogenous Pcdhg gene
cluster is important arborization. To test this in vivo, multiple novel mouse lines in which varying numbers of
Pcdhg exons have been disrupted, reducing potential isoform diversity, will be analyzed. Additionally, anxiety-
and memory-associated tests will be carried out on Pcdhg null, single-isoform overexpression, and reduced
diversity mice to link cellular phenotypes to behavioral outcomes. The proposed research is innovative,
because it utilizes CRISPR/Cas9 genome editing techniques to comp...

## Key facts

- **NIH application ID:** 10216809
- **Project number:** 3R01NS055272-13S1
- **Recipient organization:** UNIVERSITY OF IOWA
- **Principal Investigator:** JOSHUA A WEINER
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $377,705
- **Award type:** 3
- **Project period:** 2007-07-01 → 2022-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10216809

## Citation

> US National Institutes of Health, RePORTER application 10216809, Elucidating functions of the gamma-protocadherins in CNS development (3R01NS055272-13S1). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10216809. Licensed CC0.

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