Biology subjects

Gomez-Ospina, N.

Publications and source records attributed to Gomez-Ospina, N..

5 recordsLinked to original sources

bioRxiv2026

The Batten disease gene product CLN6 is a glycerophosphoglycerol epimerase that establishes S,S-BMP stereochemistry

Bis(monoacylglycero)phosphate (BMP), a lysosomal phospholipid essential for lipid catabolism and cholesterol clearance, has a noncanonical S,S glycerol configuration found in no other mammalian phospholipid, a feature necessary for its stability in the lysosome. How cells invert glycerol stereochemistry to build S,S-BMP has remained unexplained since this configuration was discovered five decades ago. Here, we show that the endoplasmic reticulum-resident Batten disease protein CLN6 is a Ca2+-dependent epimerase that isomerizes glycerophosphoglycerol (GPG) from R,S-GPG to S,S-GPG. CLN6-deficient cells, mouse tissues, and patient samples predominantly contain R,S-GPG, S,R-lysophosphatidylglycerol (LPG), and R,S-BMP instead of their S,S counterparts, with a net depletion of BMP. Purified CLN6 catalyzes GPG epimerization in vitro, an activity abolished by a pathogenic substitution in its substrate-binding pocket. Consistently, exogenous S,S-GPG restores BMP synthesis and relieves lipid storage in CLN6-null cells. Our work establishes stereochemical commitment upstream of acylation, placing CLN6, CLN8, and CLN5 in sequence in BMP biosynthesis and unifying the lipid defect across these neurodegenerative disorders.

biochemistry↗

bioRxiv2024

Cell-Type Resolved Protein Atlas of Brain Lysosomes Identifies SLC45A1-Associated Disease as a Lysosomal Disorder

Mutations in lysosomal genes cause neurodegeneration and neurological lysosomal storage disorders (LSDs). Despite their essential role in brain homeostasis, the cell-type-specific composition and function of lysosomes remain poorly understood. Here, we report a quantitative protein atlas of the lysosome from mouse neurons, astrocytes, oligodendrocytes, and microglia. We identify dozens of novel lysosomal proteins and reveal the diversity of the lysosomal composition across brain cell types. Notably, we discovered SLC45A1, mutations in which cause a monogenic neurological disease, as a neuron-specific lysosomal protein. Loss of SLC45A1 causes lysosomal dysfunction in vitro and in vivo. Mechanistically, SLC45A1 plays a dual role in lysosomal sugar transport and stabilization of V1 subunits of the V-ATPase. SLC45A1 deficiency depletes the V1 subunits, elevates lysosomal pH, and disrupts iron homeostasis causing mitochondrial dysfunction. Altogether, our work redefines SLC45A1-associated disease as a LSD and establishes a comprehensive map to study lysosome biology at cell-type resolution in the brain and its implications for neurodegeneration.

cell biology↗

bioRxiv2019

DYRK1A-related intellectual disability: a syndrome associated with congenital anomalies of the kidney and urinary tract

PurposeHaploinsufficiency of DYRK1A causes a recognizable clinical syndrome. The goal of this paper is to investigate congenital anomalies of the kidney and urinary tract (CAKUT) and genital defects (GD) in patients with DYRK1A mutations.\n\nMethodsA large database of clinical exome sequencing (ES) was queried for de novo DYRK1A mutations and CAKUT/GD phenotypes were characterized. Xenopus laevis (frog) was chosen as a model organism to assess Dyrk1as role in renal development.\n\nResultsPhenotypic details and mutations of 19 patients were compiled after an initial observation that one patient with a de novo pathogenic mutation in DYRK1A had GD. CAKUT/GD data were available from 15 patients, 11 of whom present with CAKUT/GD. Studies in Xenopus embryos demonstrate that knockdown of Dyrk1a disrupts the development of segments of developing embryonic nephrons, which ultimately give rise to the entire genitourinary (GU) tract. These defects could be rescued by co-injecting wildtype human DYRK1A RNA, but not with truncated DYRK1AR205* RNA.\n\nConclusionEvidence supports routine GU screening of all individuals with de novo DYRK1A pathogenic variants to ensure optimized clinical management. Collectively, the reported clinical data and loss of function studies in Xenopus substantiate a novel role for DYRK1A in GU development.

genetics↗

bioRxiv2018

Human genome-edited hematopoietic stem cells phenotypically correct Mucopolysaccharidosis type I

Lysosomal enzyme deficiencies comprise a large group of genetic disorders that generally lack effective treatments. A potential treatment approach is to engineer the patients own hematopoietic system to express high levels of the deficient enzyme, thereby correcting the biochemical defect and halting disease progression. Here, we present an efficient ex vivo genome editing approach using CRISPR/Cas9 that targets the lysosomal enzyme iduronidase to the CCR5 safe harbor locus in human CD34+ hematopoietic stem and progenitor cells. The modified cells secrete supra-endogenous enzyme levels, maintain long-term repopulation and multi-lineage differentiation potential, and can correct biochemical and phenotypic abnormalities in an immunocompromised mouse model of Mucopolysaccharidosis type I. Our studies provide support for the development of human, genome-edited CD34+ hematopoietic stem and progenitor cells for the treatment of a multi-systemic lysosomal storage disorder. Our safe harbor approach constitutes a flexible platform for the expression of lysosomal enzymes, exemplifying a potential new paradigm for the treatment of these diseases.

genetics↗

bioRxiv2018

Identification of Pre-Existing Adaptive Immunity to Cas9 Proteins in Humans

The CRISPR-Cas9 system has proven to be a powerful tool for genome editing, allowing for the precise modification of specific DNA sequences within a cell. Many efforts are currently underway to use the CRISPR-Cas9 system for the therapeutic correction of human genetic diseases. The most widely used homologs of the Cas9 protein are derived from the bacteria Staphylococcus aureus (S. aureus) and Streptococcus pyogenes (S. pyogenes). Based on the fact that these two bacterial species cause infections in the human population at high frequencies, we looked for the presence of pre-existing adaptive immune responses to their respective Cas9 homologs, SaCas9 (S. aureus homolog of Cas9) and SpCas9 (S. pyogenes homolog of Cas9). To determine the presence of anti-Cas9 antibodies, we probed for the two homologs using human serum and were able to detect antibodies against both, with 79% of donors staining against SaCas9 and 65% of donors staining against SpCas9. Upon investigating the presence of antigen-specific T-cells against the two homologs in human peripheral blood, we found anti-SaCas9 T-cells in 46% of donors. Upon isolating, expanding, and conducting antigen re-stimulation experiments on several of these donors anti-SaCas9 T-cells, we observed an SaCas9-specific response confirming that these T-cells were antigen-specific. We were unable to detect antigen-specific T-cells against SpCas9, although the sensitivity of the assay precludes us from concluding that such T-cells do not exist. Together, this data demonstrates that there are pre-existing humoral and cell-mediated adaptive immune responses to Cas9 in humans, a factor which must be taken into account as the CRISPR-Cas9 system moves forward into clinical trials.

immunology↗