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Published on: July 14, 2016
Hypomorphic CAMKK2 in EA.hy926 endothelial cells causes abnormal transferrin trafficking, iron homeostasis and
Mohammad Golam Sabbir1, Carla G Taylor2, Peter Zahradka3
1Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Research Centre, Winnipeg, MB, R2H 2A6, Canada; Alzo Biosciences Inc., San Diego, CA, USA.
Abstract:
We recently reported that loss of calcium/calmodulin-dependent protein kinase kinase-2 (CAMKK2), a serine/threonine kinase activated by intracellular calcium, in mice leads to tissue-specific aberrant turnover of transferrin (TF), a receptor-mediated iron-transporter that supplies iron to tissues. Iron dyshomeostasis is associated with the pathogenesis of several diseases, making TF transport relevant to health. In this study, we used hemizygous CAMKK2 hypomorphic human endothelial cell (EA.hy926) clones to demonstrate that cells with reduced CAMKK2 exhibit increased TF uptake and transcytosis, and decreased intracellular trafficking to subcellular organelles compared to wild-type. The abnormal TF trafficking in CAMKK2 hypomorphic cells correlated with a reduction in intracellular iron content and defective glucose metabolism including glycolysis and mitochondrial respiration. CAMKK2 deficiency also caused reduction in GAPDH and VDAC1 protein level which correlated to defective bioenergetics function. These findings have identified a novel mechanistic link between abnormal calcium signaling, iron dyshomeostasis and metabolic dysfunction involving CAMKK2.
Insights
Reduced calcium/calmodulin-dependent protein kinase kinase-2 (CAMKK2) impairs transferrin (TF) transport, leading to iron dyshomeostasis and defective cellular metabolism. This study links calcium signaling, iron, and metabolic dysfunction via CAMKK2.
Area of Science:
- Cell Biology
- Biochemistry
- Physiology
Background:
- Transferrin (TF) is crucial for iron transport, and its dysregulation is implicated in various diseases.
- Calcium signaling pathways, particularly involving CAMKK2, play roles in cellular functions.
- Aberrant iron homeostasis and metabolic dysfunction are key factors in numerous pathologies.
Purpose of the Study:
- To investigate the role of CAMKK2 in transferrin (TF) trafficking and cellular metabolism.
- To elucidate the mechanistic link between CAMKK2, iron homeostasis, and metabolic dysfunction.
- To characterize TF uptake, transcytosis, and intracellular trafficking in CAMKK2-deficient cells.
Main Methods:
- Utilized hemizygous CAMKK2 hypomorphic human endothelial cell (EA.hy926) clones.
- Assessed TF uptake, transcytosis, and intracellular trafficking.
- Analyzed intracellular iron content, glucose metabolism (glycolysis, mitochondrial respiration), and protein levels (GAPDH, VDAC1).
Main Results:
- Reduced CAMKK2 led to increased TF uptake and transcytosis.
- CAMKK2 deficiency resulted in decreased intracellular TF trafficking to organelles.
- Abnormal TF trafficking correlated with reduced intracellular iron, impaired glucose metabolism, and decreased GAPDH and VDAC1 protein levels.
Conclusions:
- CAMKK2 deficiency disrupts normal transferrin (TF) transport and intracellular iron handling.
- Reduced CAMKK2 impairs cellular bioenergetics, including glycolysis and mitochondrial respiration.
- A novel mechanistic link is established between calcium signaling, iron dyshomeostasis, and metabolic dysfunction mediated by CAMKK2.
