Biology subjects

Klussmann, E.

Publications and source records attributed to Klussmann, E..

2 recordsLinked to original sources

bioRxiv2019

Wnt11/Fzd7 signaling compartmentalizes AKAP2/PKA to regulate L-type Ca2+ channel

Calcium influx through the voltage-gated L-type calcium channels (LTCC) mediates a wide range of physiological processes from contraction to secretion. Despite extensive research on regulation of LTCC conductance by PKA phosphorylation in response to {beta}-adrenergic stimulation, the science remains incomplete. Here, we show that Wnt11, a non-canonical Wnt ligand, through its G protein-coupled receptor (GPCR) Fzd7 attenuates the LTCC conductance by preventing the proteolytic processing of its C terminus. This is mediated across species by protein kinase A (PKA), which is compartmentalized by A-kinase anchoring proteins (AKAP). Systematic analysis of all AKAP family members revealed AKAP2 anchoring of PKA is central to the Wnt11-dependent regulation of the channel. The identified Wnt11/AKAP2/PKA signalosome is required for heart development, controlling the intercellular electrical coupling in the developing zebrafish heart. Altogether, our data revealed Wnt11/Fzd7 signaling via AKAP2/PKA as a conserved alternative GPCR system regulating Ca2+ homeostasis.

developmental biology↗

bioRxiv2019

Endothelial PKA targets ATG16L1 to regulate angiogenesis by limiting autophagy

The cAMP-dependent protein kinase A (PKA) regulates a plethora of cellular functions in health and disease. During angiogenesis, PKA activity in endothelial cells controls the transition from sprouting to vessel maturation and limits tip cell formation independently of Notch signaling. The molecular PKA targets mediating these effects remain unknown. We report a chemical genetics screen identifying endothelial-specific substrates of PKA in human umbilical vein endothelial cells (HUVEC). We identified ATG16L1, a regulator of autophagy, as novel target of PKA. Biochemical validation, mass spectrometry and peptide spot arrays revealed that PKA phosphorylates ATG16L1 at Ser268 and ATG16L1{beta} at Ser269. The phosphorylations drive degradation of ATG16L1 protein. Knocking down PKA or inhibiting its activity increased ATG16L1 protein levels and endothelial autophagy. In vivo genetics and pharmacological experiments demonstrated that autophagy inhibition partially rescues vascular hypersprouting caused by PKA deficiency. We propose that endothelial PKA activity restricts active sprouting by reducing endothelial autophagy through phosphorylation of ATG16L1.

biochemistry↗