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Cancer cachexia is a systemic metabolic dysfunction that affects more than 80% of pancreatic cancer patients and is the leading cause of death in 22%–30% of all cancers. Because the cancer spread beyond the pancreas at the time of diagnosis, only about 20% of patients are candidates for surgery. Pancreatic cancer's aggressiveness destabilizes whole-body homeostasis by dismantling the normal network of organs crosstalk. This miss-communication favors the tumor progression during cancer cachexia, which is characterized by devastating body weight lossmuscle atrophy, fat wasting, decreased appetite. The molecular mechanisms underlying these metabolic cues are still being investigated.

Mengistu Lemecha, Jaya Prakash Chalise, Yuki Takamuku, Guoxiang Zhang, ... Keiichi Itakura

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Current Issue

Calcium/calmodulin-dependent protein kinase kinase 2 regulates hepatic fuel metabolism

Brittany A. Stork, Adam Dean, Andrea R. Ortiz, Pradip Saha, ... Brian York

 

Objective

The liver is the primary internal metabolic organ that coordinates whole body energy homeostasis in response to feeding and fasting. Genetic ablation or pharmacological inhibition of calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2) has been shown to significantly improve hepatic health and peripheral insulin sensitivity upon overnutrition with high fat diet. However, the precise molecular underpinnings that explain this metabolic protection have remained largely undefined.

Methods

To characterize the role of CaMKK2 in hepatic metabolism, we developed and challenged liver-specific CaMKK2 knockout (CaMKK2LKO) mice with high fat diet and performed glucose and insulin tolerance tests to evaluate peripheral insulin sensitivity. We used a combination of RNA-Sequencing, glucose and fatty acid istotopic tracer studies, a newly developed Seahorse assay for measuring the oxidative capacity of purified peroxisomes, and a degenerate peptide libarary to identify putative CaMKK2 substrates that mechanistically explain the protective effects of hepatic CaMKK2 ablation.

Results

Consistent with previous findings, we show that hepatic CaMKK2 ablation significantly improves indices of peripheral insulin sensitivity. Mechanistically, we found that CaMKK2 phosphorylates and regulates GAPDH to promote glucose metabolism and PEX3 to blunt peroxisomal fatty acid catabolism in the liver.

Conclusion

CaMKK2 is a central metabolic fuel sensor in the liver that significantly contributes to whole body systems metabolism.

Calcium/calmodulin-dependent protein kinase kinase 2 regulates hepatic fuel metabolism

Brittany A. Stork, Adam Dean, Andrea R. Ortiz, Pradip Saha, ... Brian York

 

Objective

The liver is the primary internal metabolic organ that coordinates whole body energy homeostasis in response to feeding and fasting. Genetic ablation or pharmacological inhibition of calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2) has been shown to significantly improve hepatic health and peripheral insulin sensitivity upon overnutrition with high fat diet. However, the precise molecular underpinnings that explain this metabolic protection have remained largely undefined.

Methods

To characterize the role of CaMKK2 in hepatic metabolism, we developed and challenged liver-specific CaMKK2 knockout (CaMKK2LKO) mice with high fat diet and performed glucose and insulin tolerance tests to evaluate peripheral insulin sensitivity. We used a combination of RNA-Sequencing, glucose and fatty acid istotopic tracer studies, a newly developed Seahorse assay for measuring the oxidative capacity of purified peroxisomes, and a degenerate peptide libarary to identify putative CaMKK2 substrates that mechanistically explain the protective effects of hepatic CaMKK2 ablation.

Results

Consistent with previous findings, we show that hepatic CaMKK2 ablation significantly improves indices of peripheral insulin sensitivity. Mechanistically, we found that CaMKK2 phosphorylates and regulates GAPDH to promote glucose metabolism and PEX3 to blunt peroxisomal fatty acid catabolism in the liver.

Conclusion

CaMKK2 is a central metabolic fuel sensor in the liver that significantly contributes to whole body systems metabolism.

2021 impact factor: 8.568

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