Melissa Asher

Entering Class - 2013

E-MAIL: asher024@umn.edu

PhD Thesis 2022

A functional endocannabinoid system in human induced pluripotent stem cell-derived cortical cultures.

Current Position:

Postdoctoral Fellow, University of Michigan

Undergraduate Institution and Major:

Michigan State University, B.S. in Genomics and Molecular Genetics, 2012

Graduate Advisor:

PhD:

Stanley Thayer, PhD

Masters:

Marija Cvetanovic, Ph.D., Department of Neuroscience

Dexcription of Graduate Research:

PhD Degree:

The endocannabinoid system is an increasingly popular therapeutic target in many neurological conditions, due in large part to its ability to protect neurons from damage caused by hyperactivity and excitotoxicity. Despite recent interest in cannabinoid-based treatments, the unavailability of human brain tissue and species differences between humans and animal models present obstacles to drug development. Human induced pluripotent-derived stem cells (hiPSCs), which can be obtained less invasively from skin samples and then reprogrammed into neurons and glia, are one possible solution to this problem, as However, it is not clear whether hiPSC-derived neurons actually have a working endocannabinoid system to study. In this thesis I characterize the endocannabinoid system in a commercially available line of hiPSC-derived cortical neuron/astrocyte cultures using calcium imaging and a fluorescent cannabinoid indicator expressed in live neurons. hiPSC-derived cultures produced and metabolized endocannabinoids in addition to responding to exogenously applied cannabinoids, indicating that they do indeed possess a fully functional endocannabinoid system. I also show that endocannabinoid synthesis evoked by a muscarinic receptor agonist in hiPSC-derived cortical cultures is not calcium-dependent, and that an inhibitor of endocannabinoid metabolism produces less receptor desensitization than a cannabinoid receptor agonist with prolonged exposure. These studies demonstrate that hiPSCderived neuron/astrocyte cultures are a powerful new tool for investigating open questions about the regulation of the human endocannabinoid system.

Masters Degree: Our lab studied the roles of diverse cell types and non-cerebellar pathology in the neurodegenerative disease spinocerebellar ataxia type 1 (SCA1). SCA1 is a dominantly inherited neurodegenerative disease which is best known for the cerebellar motor symptoms it causes, but which also includes cognitive deficits and mood disorders in many patients. My project focused on the role of Atxn1, the gene that is mutated in SCA1, and its effects on cognition and mood in mice. I found that loss and mutation of Atxn1 led to severe learning and memory deficits as well as mood abnormalities in these transgenic mice, and that only a small portion of these phenotypes could be accounted for by cerebellar pathology alone. In addition, I found that Atxn1 knockout mice had reduced hippocampal neurogenesis, which could provide an explanation for some of their learning and memory deficits.

    Graduate Publications.

    • Asher M, Rosa JG, Cvetanovic M. Mood alterations in mouse models of Spinocerebellar Ataxia type 1. Sci Rep. 2021 Jan 12;11(1):713.
    • Asher M, Rosa JC, Rainwater O, Duvick L, Bennyworth M, Lai RY, CRC-SCA, Kuo SH, Cvetanovic M. Cerebellar contribution to the cognitive alterations in SCA1: evidence from mouse models. Hum Mol Genet. 2020;29(1):117-131.
    • Wu MM, Zhang X, Asher MJ, Thayer SA. Druggable targets of the endocannabinoid system: implications for the treatment of HIV-associated neurocognitive disorder. Brain Res. 2019 Dec 1;1724:146467.
    • Asher M, Johnson A, Zecevic B, Pease D, Cvetanovic M. Ataxin-1 regulates proliferation of hippocampal neural precursors. Neuroscience. 2016;322:54-65.

    Graduate Abstracts:

    Oral Presentations:

    • A role for ataxin-1 in cognition and neurogenesis. University of Minnesota Graduate Program in Neuroscience colloquium series, Minneapolis, MN, 2016.

    Poster Presentations:

    • Asher M, Johnson A, Cvetanovic M. A role for ataxin-1 in hippocampal neurogenesis. 2016. Sixth Ataxia Investigators Meeting, Orlando, FL.

    Graduate Awards/Honors:

    • Sping and Ying Ngoh Lin Award 

    Thesis Committee Members:

    Research Areas:

    • Neurodegenerative Diseases and Neural Injury
    • Regenerative Medicine for Neural Systems

    Rotations:

    Graduate Program in Neuroscience Committees:

    • Career Facilitation Committee, 2017-2019

    Professional Outreach:

    • Presenter at a Social Science event at the Science Museum of Minnesota, Oct. 1, 2015
    • Brain Awareness Week Instructor, 2013-2016, 2018
    • State Fair Brain Booth Presenter, 2014

    Why did you choose University of Minnesota?

    I liked the strong sense of community among the students and also felt that there was a good selection of faculty with whom to rotate.

    Advice for Incoming Students:

    Choose an advisor you can work with even when things aren’t going well. It’s a lot easier to change parts of your project that you don’t like than to change the people you work with!

    melissa_asher