hormone-sensitive lipase

hormone-sensitive lipase
Name	Hormone-sensitive lipase
Ec number	3.1.1.79
Other names	HSL
Family	Carboxylesterase

hormone-sensitive lipase Hormone-sensitive lipase (HSL) is a key intracellular lipase involved in mobilizing stored lipids from adipocytes and other tissues. Discovered through studies of adipose tissue metabolism, HSL links hormonal signaling to lipid catabolism and systemic energy homeostasis. Research on HSL has intersected with work at institutions such as Harvard University, Max Planck Society, Stanford University, and University of Cambridge.

Structure and Gene

The HSL protein is encoded by the LIPE gene, initially characterized by teams at National Institutes of Health, Cold Spring Harbor Laboratory, and University of California, San Francisco. Structural studies referenced by groups at Massachusetts Institute of Technology and the European Molecular Biology Laboratory describe HSL as a ~79 kDa serine esterase with an alpha/beta hydrolase fold, typical of the carboxylesterase family, and containing an N-terminal regulatory domain and a C-terminal catalytic domain. X-ray crystallography and cryo-EM efforts at Johns Hopkins University and Oxford University have illuminated the catalytic triad (Ser, Asp, His) and substrate-binding pocket, while comparative genomics from Cold Spring Harbor Laboratory and Max Planck Society show conservation across vertebrates studied at University of Tokyo and University of Melbourne.

Mechanism of Action

HSL catalyzes hydrolysis of diacylglycerol, monoacylglycerol, and cholesteryl esters, with biochemical characterization performed by researchers at Rockefeller University, Yale University, and University of Pennsylvania. The catalytic mechanism follows a nucleophilic attack by the serine residue, stabilized by an oxyanion hole described in structural work from Karolinska Institutet and Institut Pasteur. Kinetic analyses by labs at ETH Zurich and Imperial College London show substrate specificity influenced by acyl chain length and stereochemistry, while mass spectrometry studies at Princeton University and University of Chicago have mapped reaction intermediates and product profiles.

Regulation and Signaling Pathways

HSL activity is regulated by reversible phosphorylation mediated by cyclic AMP-dependent protein kinase A (PKA) and other kinases characterized by research at University of California, San Diego, University of Oxford, and University of Cambridge. Hormonal control involving epinephrine, glucagon, insulin, and signaling pathways studied at Columbia University and Duke University modulate PKA, protein phosphatase 2A (PP2A), and AMP-activated protein kinase (AMPK) interactions examined at University of Toronto and University of Copenhagen. Adaptor proteins and 14-3-3 family members investigated at Weizmann Institute of Science and Salk Institute influence HSL localization to lipid droplets, a process linked to perilipin proteins studied at University of Glasgow and McGill University. Cross-talk with mTOR signaling and inflammatory mediators explored at University of California, Berkeley and Columbia University further integrate HSL into broader metabolic networks.

Physiological Roles and Tissue Distribution

HSL functions prominently in white and brown adipose tissues, demonstrated in comparative physiology studies at University of Wisconsin–Madison and University of California, Riverside, and contributes to steroidogenesis in endocrine organs examined at Mayo Clinic and Cleveland Clinic. Rodent models developed at The Jackson Laboratory and clinical investigations at Johns Hopkins Hospital have revealed roles in cardiac lipid metabolism, hepatic lipid remodeling, and testicular cholesterol handling documented by teams at National Institutes of Health and Karolinska Institutet. Tissue-specific expression profiling by consortia including the Human Protein Atlas and the Genotype-Tissue Expression Project highlights differential expression across humans studied at Massachusetts General Hospital and Mount Sinai Hospital.

Clinical Significance and Disease Associations

Mutations and polymorphisms in LIPE have been investigated for links to metabolic disorders by researchers at Imperial College London, University of Cambridge, and University College London. Altered HSL activity has associations with obesity, type 2 diabetes mellitus, nonalcoholic fatty liver disease (NAFLD), and atherosclerosis reported in cohort studies from Framingham Heart Study, UK Biobank, and Nurses' Health Study. HSL dysfunction has been implicated in adrenal and gonadal steroidogenesis disorders evaluated at Mayo Clinic and Massachusetts General Hospital, while oncology centers such as MD Anderson Cancer Center and Memorial Sloan Kettering Cancer Center have explored HSL's role in tumor lipid metabolism. Pharmacological modulation of HSL is a focus for biotech firms and clinical trials coordinated with Food and Drug Administration oversight and partnerships including Bill & Melinda Gates Foundation-funded initiatives.

Experimental Methods and Assays

Biochemical assays for HSL activity employ radiolabeled substrates and colorimetric methods refined at Salk Institute, Rockefeller University, and Cold Spring Harbor Laboratory. Western blotting, immunohistochemistry, and qPCR protocols have been standardized in core facilities at Harvard Medical School and Stanford School of Medicine, using antibodies validated by repositories such as Addgene and datasets curated by the Gene Expression Omnibus. Genetic manipulation via CRISPR-Cas9 and transgenic models developed at The Jackson Laboratory and genome centers like the Broad Institute enable functional studies, while lipidomics platforms at European Bioinformatics Institute and Woods Hole Oceanographic Institution provide mass spectrometry workflows for detailed lipid profiling.

Category:Lipases