Spatial Lipidomic Profiling of Mouse Joint Tissue Demonstrates the Essential Role of PHOSPHO1 in Growth Plate Homeostasis

Abstract

Lipids play a crucial role in signaling and metabolism, regulating the development and maintenance of the skeleton. Membrane lipids have been hypothesized to act as intermediates upstream of orphan phosphatase 1 (PHOSPHO1), a major contributor to phosphate generation required for bone mineralization. Here, we spatially resolve the lipid atlas of the healthy mouse knee and demonstrate the effects of PHOSPHO1 ablation on the growth plate lipidome. Lipids spanning 17 subclasses were mapped across the knee joints of healthy juvenile and adult mice using matrix-assisted laser desorption ionization imaging mass spectrometry (MALDI-IMS), with annotation supported by shotgun lipidomics. Multivariate analysis identified 96 and 80 lipid ions with differential abundances across joint tissues in juvenile and adult mice, respectively. In both ages, marrow was enriched in phospholipid platelet activating factors (PAFs) and related metabolites, cortical bone had a low lipid content, whereas lysophospholipids were strikingly enriched in the growth plate, an active site of mineralization and PHOSPHO1 activity. Spatially-resolved profiling of PHOSPHO1-knockout (KO) mice across the resting, proliferating, and hypertrophic growth plate zones revealed 272, 306, and 296 significantly upregulated, and 155, 220, and 190 significantly downregulated features, respectively, relative to wild-type (WT) controls. Of note, phosphatidylcholine, lysophosphatidylcholine, sphingomyelin, lysophosphatidylethanolamine, and phosphatidylethanolamine derived lipid ions were upregulated in PHOSPHO1-KO versus WT. Our imaging pipeline has established a spatially-resolved lipid signature of joint tissues and has demonstrated that PHOSPHO1 ablation significantly alters the growth plate lipidome, highlighting an essential role of the PHOSPHO1-mediated membrane phospholipid metabolism in lipid and bone homeostasis.

Picein alleviates oxidative stress and promotes bone regeneration in osteoporotic bone defect by inhibiting ferroptosis via Nrf2/HO‐1/GPX4 pathway

“…25 Bone homeostasis is a complex sequence of bone resorption and bone formation and integrity of bone tissue are maintained by various factors such as BMSCs, 26 osteoclasts and osteoblasts, 27 macrophages, 3 blood vessels, 28 or calcium ions. 29 Oxidative stress can cause potentially harmful effects on cells, such as protein oxidation or oxidative DNA damage, which are considered crucial reasons in triggering various pathologic changes related to tissue injury, 30 including OP. 4 Accumulating evidence demonstrated that oxidative stress is often accompanied by an increase in ROS production.…”

“…Nowadays, osteoporotic fracture has become a global health problem, leading to a significant reduction in quality of life and huge socio‐economic burden 25 . Bone homeostasis is a complex sequence of bone resorption and bone formation and integrity of bone tissue are maintained by various factors such as BMSCs, 26 osteoclasts and osteoblasts, 27 macrophages, 3 blood vessels, 28 or calcium ions 29 . Oxidative stress can cause potentially harmful effects on cells, such as protein oxidation or oxidative DNA damage, which are considered crucial reasons in triggering various pathologic changes related to tissue injury, 30 including OP 4 .…”

Database-Driven Spatially Resolved Lipidomics Highlights Heterogeneous Metabolic Alterations in Type 2 Diabetic Mice

“…Given the profound diversity of lipid structures and their multilevel spatial and dynamic complexity, a thorough examination of lipid composition with their spatial distribution in tissue would enhance our understanding of their physiological significance. Currently, spatially resolved lipidomics has been widely used to reveal tissue-specific lipid metabolism changes in cerebral ischemia, nonalcoholic fatty liver, renal cell carcinoma, and others. − …”

Studies on the role of matrix vesicles in bone mineralization: observations from micro to nanoscale

“…Phospho1 is proposed to operate within MVs by generating Pi from the hydrolysis of phosphocholine (PC) and phosphoethanolamine (PE) 134 . A recent study employing spatial metabolomics in mice growth plate confirmed the involvement of lipid metabolites related to PC and PE in mineralizing regions 135 . An intriguing discovery from a spectroscopic study is that choline can be integrated into the bone mineral, providing further evidence for their involvement in bone mienralization 136 .…”