Periodic Reporting for period 2 - BALDER (Bioactive peptides from human brown fat cells mediating metabolic control)
Periodo di rendicontazione: 2022-11-01 al 2024-04-30
Obesity doubles the risk of dying from a cardiovascular-related event and affects about 1 in 3 people in the Western world. Despite recent progress in developing anti-obesity drugs, these medications present side-effects and are not equally efficient nor easily accessible for all. Increasing the spectrum of drugs for personalized treatment strategies is therefore warranted.
The central nervous system (CNS) plays a major role in obesity by regulating appetite based on feedback systems from peripheral organs, including adipose tissue. The neuronal connections between adipose tissue and the CNS include sympathetic motor neurons as well as sensory neurons in the adipose tissue and a bidirectional interconnection between white and brown adipose tissue. White adipose tissue also communicates its energetic state to the CNS via adipokines e.g. Leptin, while mutations in this gene result in severe obesity, which can be cured by supplying recombinant Leptin protein. Less is known about endocrine feedback mechanism arising from brown adipose tissue (BAT), whereas the concept of so-called batokines is increasingly recognized. BAT is a heat-producing, energy-consuming subtype of adipose tissue. Importantly, people with a retained ability to activate their BAT are less prone to develop diabetes and other cardiometabolic diseases even when living with obesity. Exploring the BAT-brain axis therefore holds great promise in identifying novel drug candidates for counteracting the development of cardiometabolic diseases, which would be a valuable health gain for society world-wide.
In conclusion, we investigate the endocrine BAT-brain axis to delineate BAT’s role in the neuroendocrine regulation of feeding behavior. Our overall hypothesis is that the energetic state of BAT is communicated to the CNS, via batokines, to mediate appetite control (Figure 1). The overall objective is to discover novel appetite-regulating circuits controlled by batokines via the crosstalk between BAT and CNS. We are interested in signaling molecules from BAT that act in an endocrine fashion, or act in a paracrine fashion on nerve ends, in turn affecting dorsla root ganglia and modulating the innervation of BAT. Among batokines candidate molecules, we primarily focus on peptides and small proteins. Peptides have previously proven to be powerful in mediating endocrine crosstalk and our strategy allows for the discovery of unknown molecules.
The central nervous system (CNS) plays a major role in obesity by regulating appetite based on feedback systems from peripheral organs, including adipose tissue. The neuronal connections between adipose tissue and the CNS include sympathetic motor neurons as well as sensory neurons in the adipose tissue and a bidirectional interconnection between white and brown adipose tissue. White adipose tissue also communicates its energetic state to the CNS via adipokines e.g. Leptin, while mutations in this gene result in severe obesity, which can be cured by supplying recombinant Leptin protein. Less is known about endocrine feedback mechanism arising from brown adipose tissue (BAT), whereas the concept of so-called batokines is increasingly recognized. BAT is a heat-producing, energy-consuming subtype of adipose tissue. Importantly, people with a retained ability to activate their BAT are less prone to develop diabetes and other cardiometabolic diseases even when living with obesity. Exploring the BAT-brain axis therefore holds great promise in identifying novel drug candidates for counteracting the development of cardiometabolic diseases, which would be a valuable health gain for society world-wide.
In conclusion, we investigate the endocrine BAT-brain axis to delineate BAT’s role in the neuroendocrine regulation of feeding behavior. Our overall hypothesis is that the energetic state of BAT is communicated to the CNS, via batokines, to mediate appetite control (Figure 1). The overall objective is to discover novel appetite-regulating circuits controlled by batokines via the crosstalk between BAT and CNS. We are interested in signaling molecules from BAT that act in an endocrine fashion, or act in a paracrine fashion on nerve ends, in turn affecting dorsla root ganglia and modulating the innervation of BAT. Among batokines candidate molecules, we primarily focus on peptides and small proteins. Peptides have previously proven to be powerful in mediating endocrine crosstalk and our strategy allows for the discovery of unknown molecules.
We have performed in-depth analyses of human brown and white adipocytes resulting in the discovery of a new cellular subtype, the “SWAT cell” differentiating in parallel with adipocytes, from the same progenitor. This high-resolution data is key for interpreting our future work as SWAT cells are secreting the double number of factors compared to adipocytes and therefore have the potential to be highly involved in neuronal crosstalk. These findings are published in Nature Metabolism.
We have used a machine learning based prediction tool to shortlist our human brown adipocyte (including both adipogenic and SWAT cells) peptidomics data for different bioactivity classes. We found hundreds of peptides with a high prediction score for neuropeptides. Based on this prediction, we have initially tested the top 50 peptides for their potential role in activating neuronal cells.
We have established a valuable collaboration with Dr Søren Nielsen at Rigshospitalet who has expertise within long read sequencing. This collaboration has accelerated our work on predicting microproteins from small open reading frames. The library of potential microproteins will now be passed through our pipeline for prediction of neuronal bioactivity and thereafter high content screening for neuronal signaling.
We are continuing to develop a neuronal platform for high content screening. To date, we have optimized the methodology for RNAscope based detection of neuronal specificity and activity using automized quantification and are further establishing live cell imaging and microelectrode arrays for monitoring the effects of candidate molecules. We are working with several different neuronal in vitro models derived from human, rat and mice. To date, we have screened over 50 peptides and small proteins, and have identified around 8 candidates for which we are currently planning in vivo studies.
We have used a machine learning based prediction tool to shortlist our human brown adipocyte (including both adipogenic and SWAT cells) peptidomics data for different bioactivity classes. We found hundreds of peptides with a high prediction score for neuropeptides. Based on this prediction, we have initially tested the top 50 peptides for their potential role in activating neuronal cells.
We have established a valuable collaboration with Dr Søren Nielsen at Rigshospitalet who has expertise within long read sequencing. This collaboration has accelerated our work on predicting microproteins from small open reading frames. The library of potential microproteins will now be passed through our pipeline for prediction of neuronal bioactivity and thereafter high content screening for neuronal signaling.
We are continuing to develop a neuronal platform for high content screening. To date, we have optimized the methodology for RNAscope based detection of neuronal specificity and activity using automized quantification and are further establishing live cell imaging and microelectrode arrays for monitoring the effects of candidate molecules. We are working with several different neuronal in vitro models derived from human, rat and mice. To date, we have screened over 50 peptides and small proteins, and have identified around 8 candidates for which we are currently planning in vivo studies.
Through our high-resolution investigation of human brown and white adipocytes, we discovered a novel cell type, the SWAT cell, which is highly relevant in terms of studying adipocyte secretomes. Our findings are published in Nature Metabolism and was further supported by a back-to back publication from Silvia Corvera’s lab at UMASS. Corvera obtained supporting and complementary findings demonstrating that SWAT cells are held in a multipotent state by Wnt signaling.
Using a machine-learning based tool for predicting peptide bioactivity classes, and long-read sequencing and prediction of microproteins, we have identified hundreds of peptides with sequence similarities to neuropeptides and thus likely to signal in a neuronal context, supporting our initial hypothesis of an existing crosstalk.
These peptides are now being tested in our neuronal platform for high content screening and we have so far had great progress in identifying promising candidates in neurite outgrowth as well as in acute neuronal activation or deactivation.
We have initial data on a small candidate protein being secreted from brown adipocytes and playing a key role in neuronal differentiation. We are currently designing in vivo and in vitro models to assess this crosstalk further.
By the end of the project, we expect to have identified several peptides forming a bidirectional BAT-neuro axis. From a larger perspective, this project has the potential of providing deeper insights into which mechanisms promote a healthy regulation of human metabolism.
Using a machine-learning based tool for predicting peptide bioactivity classes, and long-read sequencing and prediction of microproteins, we have identified hundreds of peptides with sequence similarities to neuropeptides and thus likely to signal in a neuronal context, supporting our initial hypothesis of an existing crosstalk.
These peptides are now being tested in our neuronal platform for high content screening and we have so far had great progress in identifying promising candidates in neurite outgrowth as well as in acute neuronal activation or deactivation.
We have initial data on a small candidate protein being secreted from brown adipocytes and playing a key role in neuronal differentiation. We are currently designing in vivo and in vitro models to assess this crosstalk further.
By the end of the project, we expect to have identified several peptides forming a bidirectional BAT-neuro axis. From a larger perspective, this project has the potential of providing deeper insights into which mechanisms promote a healthy regulation of human metabolism.