Measurement of cell-type specific somatic mutation rates in the aging human brain - Resubmission – 1

Project summary/Abstract Research: The human brain contains over 100 diverse classes and subclasses of neurons and glia, making it the most heterogenous organ in the body. Recent studies have revealed that during aging, brain cells accumulate somatic mutations with patterns that reflect diverse mutagenic factors. However, to date, these

studies have been unable to systematically profile aging-related somatic mutation rates (SMRs) of specific brain cell types due to the lack of methods to isolate specific cell types from human brain tissue without the process of fixation, which precludes high-fidelity sequencing necessary for measuring SMRs. This proposal

aims to fill this knowledge gap by developing a method to isolate potentially any cell type from post-mortem human brain, while avoiding fixation in order to preserve the integrity of the genome for high-fidelity DNA- sequencing (DNA-seq) and analysis of SMRs. Understanding how SMRs and mutational signatures differ

among cell types in the brain is important, because it is a prerequisite for assessing the possible role of somatic mutations and genome integrity in age-related brain diseases that often involve specific cell types. The proposal’s aims are: 1) To develop a novel technology to isolate unfixed nuclei of any cell type from frozen

post-mortem human brains, a method which will also potentially be applicable to any tissue; 2) To determine SMRs across age spans for four specific human brain cell types relevant to age-related brain diseases. Successful completion of this proposal will enable future studies of somatic mutations and other molecular

profiling that is precluded by fixation in potentially any cell type and brain region in the context of diverse age- related brain disorders. Training Plan: Under this award, I will 1) Expand my scientific knowledge of the mechanisms of mutagenesis and genome integrity generally, and in the context of the aging human brain; 2)

Gain computational and bioinformatics expertise in genomics and DNA-seq analysis; 3) Conduct career development activities for successful transition towards a future independent academic research career. Environment: The proposed research and training plans will be conducted in the laboratory of Dr. Gilad Evrony,

MD, PhD, at the Center for Human Genetics and Genomics (CHGG) at NYU Grossman School of Medicine (NYUSOM), with co-mentorship from the Center’s director, Dr. Aravinda Chakravarti, PhD. NYUSOM is an environment with well-respected and established research groups dedicated to trainees’ success. Dr. Evrony is

a pioneer and expert in single-cell genomics and computational genomics, providing a rigorous and supportive research environment along with career mentorship. Dr. Chakravarti is a renowned expert in human genetics and genomics, as well as statistics, who will provide further guidance on scientific, computational, and career

goals. Both laboratories, the collaborating research community, and our affiliations with the Neuroscience and Systems Genetics Institutes, provide a unique environment to integrate neuroscience and genomics training, and to expand scientific and career-advancement activities to aid my transition towards independence.