Periodic Reporting for period 2 - SPHERES (Lipid droplet hypertrophy : the link between adipocyte dysfunction and cardiometabolic diseases)
Berichtszeitraum: 2022-03-01 bis 2023-08-31
Increased adipocyte size is the single adipose characteristic most strongly linked to cardiometabolic diseases, the most prevalent chronic non-communicable disease worldwide. Surprisingly, almost nothing is known about the underlying mechanisms and whether it can be therapeutically targeted. Deploying approaches ranging from biophysical to cellular and whole-body investigations, SPHERES addresses these fundamental biologically and clinically relevant issues. The goal of SPHERES is to understand the dynamics and consequences of adipocyte hypertrophy (enlargement) through investigation of its large lipid droplet.
The initial part of the project was chiefly devoted to the development of beyond-state-of-the-art models and methods.
The Rydén ( lab with the help of Lauschke group and Langin labhave set up human and mouse 3D cell models referred to as adipocyte spheroids (Shen et al. , Adv Sci, 2021, 8, e2100106, doi:10.1002/advs.202100106). Adipocyte spheroids show better levels of differentiation yielding to paucilocular and unilocular adipocytes never observed in 2D cultures. . The expertise has been transferred to the Antonny lab.
Mejhert, now working with Rydén, has been a major contributor to the building of the lipid droplet knowledge portal (https://lipiddroplet.org/(öffnet in neuem Fenster)) with Drs. Farese and Walther. The portal is integrating data from relevant studies on lipid droplets (Mejhert et al. Dev Cell. 2022 57:387-397.e4. doi: 10.1016/j.devcel.2022.01.003.).
In the Langin lab with the help of Concordet TACGENE core facility, CRISPR/Cas9 gene editing was used to generate with remarkable knock out efficiency in two different mouse strains (Recazens et al. JCI Insight, 2022, 7, doi:10.1172/jci.insight.153431). Similar success was achieved to modify gene sequences using CRISPR/Cas9-based knock-in.
Copic and d’Ambrosio identified the molecular determinants that allow perilipin 4 to form a stable coat surface on lipid droplets (Elife. 2021 10:e61401. doi: 10.7554/eLife.61401). The stable arrangements of adjacent amphipathic helices via polar/electrostatic interactions is reminiscent of the organization of apolipoproteins in lipoprotein particles.
Rydén’s lab has established methods to isolate adipocyte organelles and lipid droplets. Comprehensive proteome analyses have been performed in white adipose tissues from subjects with or without obesity. Tools have been produced in the Langin and Antonny labs to use TurboID in various cellular contexts including human immortalized adipose stem cells. This proximity labelling technique provides a landscape of the molecular environment of the lipid droplet proteins of choice. Langin’s lab also made progress in advanced imaging of adipocyte size using a deep learning-based segmentation method currently applied to hundreds of adipose tissue samples.
Rydén lab has made breakthroughs by identifying three distinct white adipocyte subtypes in human whiteadipose tissue that respond qualitatively differently to insulin stimulation in vivo (Bäckdahl et al, Cell Metabolism, 2021, 33:1869-1882). These results suggest that white adipose tissue is a much more heterogeneous tissue than previously thought and that not only cell size but also cell type impacts the inter-individual differences in metabolic phenotype. The laboratory has also performed transcriptomic analyses to measure insulin sensitivity in vivo in never-obese as well as in individuals with obesity before and after weight loss (Mileti et al, Diabetes 2021,70:1486-1497).
Studies of the bioenergetic state of human fat cells in Rydén lab led to the identification of several pathways linked to disturbed adipose tissue function. Among these, the interconversion of creatine and phosphocreatine is attenuated in the obese insulin resistant state and increases the levels of phosphocreatine (Maqdasy et al, Nature Metabolism, 2022, 4, 190:2020-202). This results in a compensatory increase in glycolysis and ATP production, which stimulates a pro-inflammatory response in both human and murine white adipocytes.
During the initial phase of the project, Langin lab together with Rydén group also reviewed the adipocyte cell models available describing their main characteristics, culture conditions, advantages and limitations (Dufau et al., 2021, Am J Physiol Cell Physiol. 320:C822-C841). The consortium (Langin and Rydén lab) also reviewed the current understanding of lipid and glucose metabolic pathways in the white adipocyte (Morigny et al, Nature Reviews Endocrinology, 2021, 17:276-295). The article surveys recent advance in humans on the importance of adipocyte hypertrophy and on in vivo turnover of adipocytes and stored lipids. At molecular level, it describes the novel regulators and interplays which control the fine-tuning between fatty acid and glucose metabolic fates in different physiological states. It also examines the metabolic alterations involved in the genesis of obesity-associated metabolic disorders, lipodystrophic states, cancers and cachexia. The review concludes on the potential of targeting white fat metabolism for improved patient stratification and the wide, yet not exploited, range of therapeutic opportunities.
The Rydén ( lab with the help of Lauschke group and Langin labhave set up human and mouse 3D cell models referred to as adipocyte spheroids (Shen et al. , Adv Sci, 2021, 8, e2100106, doi:10.1002/advs.202100106). Adipocyte spheroids show better levels of differentiation yielding to paucilocular and unilocular adipocytes never observed in 2D cultures. . The expertise has been transferred to the Antonny lab.
Mejhert, now working with Rydén, has been a major contributor to the building of the lipid droplet knowledge portal (https://lipiddroplet.org/(öffnet in neuem Fenster)) with Drs. Farese and Walther. The portal is integrating data from relevant studies on lipid droplets (Mejhert et al. Dev Cell. 2022 57:387-397.e4. doi: 10.1016/j.devcel.2022.01.003.).
In the Langin lab with the help of Concordet TACGENE core facility, CRISPR/Cas9 gene editing was used to generate with remarkable knock out efficiency in two different mouse strains (Recazens et al. JCI Insight, 2022, 7, doi:10.1172/jci.insight.153431). Similar success was achieved to modify gene sequences using CRISPR/Cas9-based knock-in.
Copic and d’Ambrosio identified the molecular determinants that allow perilipin 4 to form a stable coat surface on lipid droplets (Elife. 2021 10:e61401. doi: 10.7554/eLife.61401). The stable arrangements of adjacent amphipathic helices via polar/electrostatic interactions is reminiscent of the organization of apolipoproteins in lipoprotein particles.
Rydén’s lab has established methods to isolate adipocyte organelles and lipid droplets. Comprehensive proteome analyses have been performed in white adipose tissues from subjects with or without obesity. Tools have been produced in the Langin and Antonny labs to use TurboID in various cellular contexts including human immortalized adipose stem cells. This proximity labelling technique provides a landscape of the molecular environment of the lipid droplet proteins of choice. Langin’s lab also made progress in advanced imaging of adipocyte size using a deep learning-based segmentation method currently applied to hundreds of adipose tissue samples.
Rydén lab has made breakthroughs by identifying three distinct white adipocyte subtypes in human whiteadipose tissue that respond qualitatively differently to insulin stimulation in vivo (Bäckdahl et al, Cell Metabolism, 2021, 33:1869-1882). These results suggest that white adipose tissue is a much more heterogeneous tissue than previously thought and that not only cell size but also cell type impacts the inter-individual differences in metabolic phenotype. The laboratory has also performed transcriptomic analyses to measure insulin sensitivity in vivo in never-obese as well as in individuals with obesity before and after weight loss (Mileti et al, Diabetes 2021,70:1486-1497).
Studies of the bioenergetic state of human fat cells in Rydén lab led to the identification of several pathways linked to disturbed adipose tissue function. Among these, the interconversion of creatine and phosphocreatine is attenuated in the obese insulin resistant state and increases the levels of phosphocreatine (Maqdasy et al, Nature Metabolism, 2022, 4, 190:2020-202). This results in a compensatory increase in glycolysis and ATP production, which stimulates a pro-inflammatory response in both human and murine white adipocytes.
During the initial phase of the project, Langin lab together with Rydén group also reviewed the adipocyte cell models available describing their main characteristics, culture conditions, advantages and limitations (Dufau et al., 2021, Am J Physiol Cell Physiol. 320:C822-C841). The consortium (Langin and Rydén lab) also reviewed the current understanding of lipid and glucose metabolic pathways in the white adipocyte (Morigny et al, Nature Reviews Endocrinology, 2021, 17:276-295). The article surveys recent advance in humans on the importance of adipocyte hypertrophy and on in vivo turnover of adipocytes and stored lipids. At molecular level, it describes the novel regulators and interplays which control the fine-tuning between fatty acid and glucose metabolic fates in different physiological states. It also examines the metabolic alterations involved in the genesis of obesity-associated metabolic disorders, lipodystrophic states, cancers and cachexia. The review concludes on the potential of targeting white fat metabolism for improved patient stratification and the wide, yet not exploited, range of therapeutic opportunities.
Using the innovative technologies developed during the first phase of the project combined with the development of novel cellular and murine models and unique clinical cohorts, we will determine the role of lipid droplet-associated proteins and their protein interactomes in determining lipid droplet and adipocyte function. The work has been initiated on the role of specific lipid droplet proteins. Similarly, progress is being made on lipid dynamics and interactions within adipocyte lipid droplets.