Periodic Reporting for period 1 - HisPO (Histidine Phosphorylation and Obesity)
Berichtszeitraum: 2020-05-01 bis 2022-04-30
Protein histidine phosphorylation is a poorly characterized post-translational modification. Its importance in mammalian cellular function is emerging from the discovery of histidine kinases and phosphatases and their substrates. Recently, histidine phosphorylation has been involved in heart failure and cancer. Obesity and type 2 diabetes remain challenging disorders due to growing prevalence around the world and poorly efficient treatments. Regarding metabolic disorders, histidine phosphorylation state has been associated with insulin secretion regulation in pancreas. However, the role of histidine phosphorylation in insulin sensitivity in liver, skeletal muscle or adipose tissue and/or in obesity is still not known.
The main aim of the present project was to determine whether protein histidine phosphorylation plays a role in obesity-associated metabolic dysfunction. Thus, we determined if obesity modify global histidine phosphorylation level, histidine kinases and phosphatases expression or activity, and specific protein histidine phosphorylation. Then, we wanted to evaluate whether a change of histidine phosphorylation level can impact whole-body glucose metabolism and body weight/composition by using transgenic mice deficient in the main histidine phosphatase, LHPP.
The main aim of the present project was to determine whether protein histidine phosphorylation plays a role in obesity-associated metabolic dysfunction. Thus, we determined if obesity modify global histidine phosphorylation level, histidine kinases and phosphatases expression or activity, and specific protein histidine phosphorylation. Then, we wanted to evaluate whether a change of histidine phosphorylation level can impact whole-body glucose metabolism and body weight/composition by using transgenic mice deficient in the main histidine phosphatase, LHPP.
The main objective of my proposed action was to determine if histidine phosphorylation changes upon obesity and to investigate the role of histidine phosphorylation in systemic glucose homeostasis. To achieve this, we used mice that were fed with a lipid rich diet to make them obese. We examined global pHis in the metabolic tissues of these animals. For that purpose, we used antibodies against phosphohistidine, developed at the Salk Institute (Tony Hunter lab) specifically recognizing the phosphoester (P-O) bond in serine, threonine, and tyrosine phosphorylation, the phosphoramidate (P–N) bond in pHis. We also used genetically modified animals to assess the impact of the loss of the most important phosphohistidine phosphatase the lysine-histidine-pyrophosphate phosphatase (LHPP). We evaluated metabolic phenotype of these mice to link any metabolic dysfunction with a change in histidine phosphorylation level.
We did not observe strong changes in global histidine phosphorylation in insulin sensitive organs from mice fed with a normal compared to a high-fat diet. The analysis of the LHPP KO animals mostly show changes in brown adipose tissue in favor with its activation.
Together, our study provides good preliminary results to be pursued to further explore the role of histidine phosphorylation in metabolic disease. The need of methodological improvements to study this post-translational modification is however still needed to ameliorate the amount and relevance of the obtained results.
We did not observe strong changes in global histidine phosphorylation in insulin sensitive organs from mice fed with a normal compared to a high-fat diet. The analysis of the LHPP KO animals mostly show changes in brown adipose tissue in favor with its activation.
Together, our study provides good preliminary results to be pursued to further explore the role of histidine phosphorylation in metabolic disease. The need of methodological improvements to study this post-translational modification is however still needed to ameliorate the amount and relevance of the obtained results.
Understanding a completely new area of biology and applying it to a disease with a growing prevalence is a major step in basic research. The proposed project may lead to discoveries on the role of histidine phosphorylation in physiology and pathophysiology, and in turn lead to new therapeutic strategies. There is need for such strategies because medical studies have shown that glucose-lowering drugs have little long-term benefits in diabetic patients. Indeed, it remains relevant to pursue basic research in this area and broaden our knowledge on the underlying mechanisms of metabolic disorders.