Andrew Garrett

Office location

7322 Scott Hall
540 E Canfield
Detroit, Michigan 48201

Biography

The Garrett lab is interested in how developing neurons use cell-surface recognition molecules called cell adhesion molecules (CAMs) during neural circuit formation. Our focus is on the process of self-avoidance, which prevents sister neurites from the same cell (“self”) and from cells of the same type (“homotypic”) from becoming entangled with each other. Our model is the mouse retina, where both self- and homotypic-avoidance is important for the orderly organization of the ~100 distinct types of neurons that process visual information.

Neurons use two different strategies to promote self-avoidance. The first relies on extreme molecular diversity to provide each neuron with a unique “barcode”, allowing it to distinguish “self” from “non-self”. In mammals, this is typified by the clustered protocadherins (Pcdhs), members of the cadherin superfamily of CAMs. We focus on the gamma cluster, which is composed of 22 different isoforms, and is required for normal self-avoidance in starburst amacrine cells. We use combinations of gene editing and gene delivery techniques to ask questions about isoform diversity and specific isoform functions.

The second strategy neurons use for self-avoidance does not depend on molecular diversity. The Dscams (Down syndrome cell adhesion molecule, or DSCAM, and the similar DSCAML1) are members of the Ig superfamily of CAMs required for self-avoidance and homotypic avoidance. Dscams in mammals are not diverse, but functionally interact with other CAM systems to mask excessive adhesion allowing neurites to be indifferent to each other. When left unopposed in Dscam mutants, unmasked adhesion pulls neurites into fascicles and cell bodies into homotypic clusters. We use in vivo and in vitro techniques to investigate mechanisms of adhesive masking, and how they differ between cell types.

Education

B.S., Cedarville University, 2004 (Biology)

Ph.D., University of Iowa, 2009 (Neuroscience)

Faculty appointments

Associate Professor, Department of Pharmacology and Department of Ophthalmology, Visual, and Anatomical Sciences

Publications

Hanes CM, Steffen DM, Murray GC, Burgess RW, Weiner JA, Garrett AM. A new mouse mutant with a discrete mutation in Pcdhgc5 reveals that the Protocadherin gammaC5 isoform is not essential for dendrite arborization in the cerebral cortex. Plos One. 03/2026;21(3):e0344863. doi: https://doi.org/10.1371/journal.pone.0344863.
McLeod CM, Son S, Haque MN, HanesCM , Garrett AM. Reduced neuronal self-avoidance in mouse starburst amacrine cells with only one Pcdhg isoform. Developmental Neurobiology. 01/2026;86(1):e70005. doi: https://doi.org/10.1002/dneu.70005.
McLeod CM, Lanthier HG, Nitschke GR, Bhandari S, Humphries AC, Garrett AM. Protocadherin γC4 promotes neuronal survival in the mouse retina through its variable cytoplasmic domain. Molecular Neurobiology. 07/2025. doi: doi: 10.1007/s12035-025-05239-z.
McLeod CM, Hanes CM, Fuller LC, Bhandari S, Lanthier HG, Burgess RW, Weiner JA, Garrett AM. A New Targeted Transgenic Mouse Line for the Study of Protocadherin γC4. Genesis. 02/2025;63(1):e70010. PubMed PMID: 39923243. doi: 10.1002/dvg.70010.
Hanes CM, Mah KM, Steffen DM, McLeod CM, Marcucci CG, Fuller LC, Burgess RW, Garrett AM, Weiner JA. A C-terminal motif containing a PKC phosphorylation site regulates γ-Protocadherin-mediated dendrite arborization in the cerebral cortex in vivo. Developmental Neurobiology. 07/2024;84(3):217-235. PubMed PMID: 38837880. doi: 10.1002/dneu.22950.
Meltzer S, Comeau K, Chirila A, Osei-Asante E, DeLisle M, Zhang Q, Kalish BT, Tasnim A, Huey E, Fuller LC, Flaherty EK, Maniatis T, Garrett AG, Weiner JA, Ginty DD. γ-Protocadherins control synapse formation and peripheral branching of touch sensory neurons. Neuron. 04/2023. doi: 10.1016/j.neuron.2023.03.012.
Bohl J, Gope J, Sharpe Z, Shehu A, Garrett AM, Koehler C, Hellmer C, Ichinose T. OFF Starburst Amacrine Cells in the Retina Trigger Looming-evoked Fear Responses in Mice. eNeuro. 04/2023. doi: 10.1523/ENEURO.0183-22.2023.
Steffen DM, Hanes CM, Mah KM, Ramos PV, Bosch PJ, Hinz DC, Radley JJ, Burgess RW, Garrett AM, Weiner JA. A Unique Role for Protocadherin γC3 in Promoting Dendrite Arborization through an Axin1-Dependent Mechanism. J Neurosci. 02/2023;43(6):918-935. PubMed PMID: 36604170. doi: 0.1523/JNEUROSCI.0729-22.2022.
Garrett AM, Bosch PJ, Steffen DM, Fuller LC, Marcucci CG, Koch AA, Bais P, Weiner JA, Burgess RW (2019) CRISPR/Cas9 interrogation of the mouse Pcdhg gene cluster reveals a crucial isoform-specific role for Pcdhgc4. PLoS Genetics 15(12): e1008554. https://doi.org/10.1371/journal.pgen.1008554
Garrett AM, Khalil A, Walton DO, Burgess RW. DSCAM promotes self-avoidance in the developing mouse retina by masking the functions of cadherin superfamily members. Proceedings of the National Academy of Sciences. Oct 2018, 115 (43) E10216-E10224.
Garrett AM, Tadenev AL, Hammond YT, Fuerst PG, Burgess RW. Replacing the PDZ-interacting C-termini of DSCAM and DSCAML1 with epitope tags causes different phenotypic severity in different cell populations. Elife. 2016 Sep 16;5.
Garrett AM, Jucius TJ, Sigaud LP, Tang FL, Xiong WC, Ackerman SL, Burgess RW. Analysis of Expression Pattern and Genetic Deletion of Netrin5 in the Developing Mouse. Frontiers in Molecular Neuroscience. 2016;9:3.
Garrett AM, Schreiner D, Lobas MA, Weiner JA. γ-protocadherins control cortical dendrite arborization by regulating the activity of a FAK/PKC/MARCKS signaling pathway. Neuron. 2012 Apr 26;74(2):269-76.
Garrett AM, Weiner JA. Control of CNS synapse development by gamma-protocadherin-mediated astrocyte-neuron contact. Journal of Neuroscience. 2009 Sep 23;29(38):11723-31.

Andrew Garrett

Andrew Garrett

Office location

Biography

Education

Faculty appointments

Publications

Courses taught by Andrew Garrett

Fall 2026 (current)

Winter Term 2026

Winter Term 2025

Winter Term 2024