Brain cell type specific proteomics approach to discover pathological mechanisms in the childhood CNS disorder mucolipidosis type IV

Madison Sangster; Sanjid Shahriar; Zachary Niziolek; Maria Carla Carisi; Michael Lewandowski; Bogdan Budnik; Yulia Grishchuk

doi:10.3389/fnmol.2023.1215425

Brain cell type specific proteomics approach to discover pathological mechanisms in the childhood CNS disorder mucolipidosis type IV

Front Mol Neurosci. 2023 Aug 7:16:1215425. doi: 10.3389/fnmol.2023.1215425. eCollection 2023.

Authors

Madison Sangster¹, Sanjid Shahriar², Zachary Niziolek³, Maria Carla Carisi¹, Michael Lewandowski², Bogdan Budnik², Yulia Grishchuk¹

Affiliations

¹ Center for Genomic Medicine and Department of Neurology, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, MA, United States.
² Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, United States.
³ Bauer Flow Cytometry Core, Harvard University, Cambridge, MA, United States.

Abstract

Mucolipidosis IV (MLIV) is an ultra-rare, recessively inherited lysosomal disorder resulting from inactivating mutations in MCOLN1, the gene encoding the lysosomal cation channel TRPML1. The disease primarily affects the central nervous system (CNS) and manifests in the first year with cognitive and motor developmental delay, followed by a gradual decline in neurological function across the second decade of life, blindness, and premature death in third or fourth decades. Brain pathology manifestations in MLIV are consistent with hypomyelinating leukodystrophy with brain iron accumulation. Presently, there are no approved or investigational therapies for MLIV, and pathogenic mechanisms remain largely unknown. The MLIV mouse model, Mcoln1^-/- mice, recapitulates all major manifestations of the human disease. Here, to better understand the pathological mechanisms in the MLIV brain, we performed cell type specific LC-MS/MS proteomics analysis in the MLIV mouse model and reconstituted molecular signatures of the disease in either freshly isolated populations of neurons, astrocytes, oligodendrocytes, and neural stem cells, or whole tissue cortical homogenates from young adult symptomatic Mcoln1^-/- mice. Our analysis confirmed on the molecular level major histopathological hallmarks of MLIV universally present in Mcoln1^-/- tissue and brain cells, such as hypomyelination, lysosomal dysregulation, and impaired metabolism of lipids and polysaccharides. Importantly, pathway analysis in brain cells revealed mitochondria-related alterations in all Mcoln1^-/- brain cells, except oligodendrocytes, that was not possible to resolve in whole tissue. We also report unique proteome signatures and dysregulated pathways for each brain cell population used in this study. These data shed new light on cell-intrinsic mechanisms of MLIV and provide new insights for biomarker discovery and validation to advance translational studies for this disease.

Keywords: TRPML1; biomarkers; brain cells; cell specific proteomics; central nervous system; lysosomal disease; mucolipidosis.