Updated: May 13, 2026

Preparation of Human Tissues Embedded in Optimal Cutting Temperature Compound for Mass Spectrometry Analysis
Published on: April 27, 2021
Alejandro Garanto1, Nawajes A Mandal, Meritxell Egido-Gabás
1Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.
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This study explored the role of a protein called Ceramide Kinase-Like (CERKL) in the retinas of mice. Researchers compared retinas from normal mice and mice lacking the Cerkl gene. They found that the absence of CERKL led to a significant drop in certain types of sphingolipids, specifically glucosyl and galactosyl ceramides. These lipids are important for maintaining retinal health. However, other types of lipids, like phospholipids and neutral lipids, were not affected. The study also found that CERKL binds to these sphingolipids but does not act as a ceramide kinase as previously thought. These results suggest that CERKL plays a specific role in sphingolipid metabolism in the retina and may be involved in retinal degenerative diseases.
Area of Science:
Background:
The role of sphingolipids in retinal health remains underexplored. While sphingolipids are known to influence membrane stability and cellular signaling, their specific contributions to retinal function are not fully understood. Prior research has shown that ceramide and its derivatives regulate processes like apoptosis and membrane conductance in neurons. However, the specific involvement of sphingolipids in retinal disorders is unclear. A gap exists regarding how ceramide kinase-like (CERKL) mutations affect retinal lipid composition. No prior work had resolved whether CERKL functions as a ceramide kinase or if it interacts with other sphingolipid species. This uncertainty drove the need for a detailed lipidomic analysis of the mouse retina. The study aimed to address this by comparing wild-type and Cerkl knockout retinas. Understanding these relationships could clarify the metabolic pathways disrupted in retinal degeneration. This work builds on existing knowledge of sphingolipid roles in general cellular function.
The main finding is a 30–60% decrease in retinal sphingolipid content, especially glucosyl and galactosyl ceramide species, in Cerkl knockout mice compared to wild-type controls.
The researchers used ultra-performance liquid chromatography-time-of-flight mass spectrometry (UPLC-TOF) to analyze the retinal sphingolipidome.
The study found that these species showed the most significant decrease, suggesting a specific role for CERKL in their metabolism, though its exact mechanism remains unclear.
The assays showed evidence of CERKL binding to glucosyl ceramide, galactosyl ceramide, and sphingomyelin, but not as a ceramide kinase.
Purpose Of The Study:
This study aimed to investigate the role of Ceramide Kinase-Like (CERKL) in retinal sphingolipid metabolism. The researchers focused on comparing the sphingolipid composition of wild-type and Cerkl knockout mouse retinas. They used UPLC-TOF to analyze the lipidome and identify potential CERKL substrates. The goal was to determine whether CERKL functions as a ceramide kinase or interacts with other sphingolipid species. The study also sought to assess how CERKL deficiency affects retinal lipid levels. By measuring sphingolipid content and using protein-lipid overlay assays, the researchers aimed to uncover new functional roles for CERKL. This approach allowed them to test hypotheses about CERKL's enzymatic activity and its contribution to retinal health. The findings could provide insights into the molecular mechanisms underlying retinal degenerative diseases.
Main Methods:
The researchers employed ultra-performance liquid chromatography-time-of-flight mass spectrometry (UPLC-TOF) to analyze the retinal sphingolipidome. They compared lipid profiles from wild-type and Cerkl knockout mouse retinas. The study focused on quantifying sphingolipid levels and identifying species-specific changes. Phosphorus quantification was used to assess sphingolipid content in retinal samples. Protein-lipid overlay assays were conducted to determine CERKL binding to sphingolipid species. The team examined interactions between CERKL and glucosyl ceramide (GlcCer), galactosyl ceramide (GalCer), and sphingomyelin. The experimental design allowed for a detailed comparison of lipidomic changes in the absence of CERKL. These methods provided a comprehensive view of how CERKL deficiency affects retinal lipid metabolism.
Main Results:
The study found a significant decrease in retinal sphingolipid content in Cerkl knockout mice compared to wild-type controls. The reduction ranged from 30% to 60%, with the most pronounced effects observed in glucosyl and galactosyl ceramide species. Phospholipid and neutral lipid levels remained unchanged in the same samples. These findings suggest a specific role for CERKL in sphingolipid metabolism rather than general lipid regulation. The researchers also observed evidence of CERKL binding to GlcCer, GalCer, and sphingomyelin. However, no clear evidence supported CERKL's function as a ceramide kinase. The data indicate that CERKL may interact with sphingolipid substrates in a non-kinase manner. These results challenge the initial hypothesis that CERKL functions as a ceramide kinase and suggest alternative roles.
Conclusions:
The authors concluded that CERKL plays a role in retinal sphingolipid metabolism. The observed decrease in glucosyl and galactosyl ceramide levels in Cerkl knockout mice supports this conclusion. However, the data do not confirm CERKL's function as a ceramide kinase. Instead, the evidence suggests that CERKL may bind to sphingolipid species like GlcCer and GalCer. These findings question the initial assumption that CERKL functions as a kinase and highlight the need for further investigation. The study opens new possibilities regarding CERKL's role in lipid homeostasis. The results suggest that CERKL's involvement in retinal health may be more complex than previously thought. The authors propose that future research should explore alternative functions of CERKL in sphingolipid metabolism.
No, phospholipid and neutral lipid levels remained unchanged in Cerkl knockout retinas, indicating a specific effect on sphingolipids.
The findings suggest that CERKL may contribute to retinal health through sphingolipid regulation, offering new insights into retinal degenerative diseases like Retinitis Pigmentosa.