Study on chronic heart failure using mutant phospholamban transgenic mice

Phospholamban (PLN), an integral membrane protein of cardiac sarcoplasmic reticulumreversibly inhibits the Ca D12+ D1-ATPase (SERCA) to play a pivotal role in the regulation ofcardiac contractility and relaxation.我们examined the molecular mechanism of SERCA inhibition by PLN我们已经创造了转移mice in which the dominant，高inhibitory PLN mutant proteins are overexpressed in collaboration with Dr. d.h. MacLennan ofToronto University . Our results are following:1. PLN interacts with SERCA through at leasttwo, possibly three sites；cytoplasmic domain (domain Ia), transmembrane helix (domain II)，与cytoplasmic-membrane boundary (domain Ib). Intramembrane interactions are inhibitory on SERCAactivity,while the cytoplasmic interactions are not inhibitory self although it is essential for thephysiological regulatory effect.我们提供PLN and SERCA interact通过一个四基地circuitthrough which long range inhibitory interactions night be propagated among a series of cytoplasmic2. PLN transmembrane domain interacts with the transmembranesequence (M6) of SERCA. The interaction site consists of four residues which form The hydrophobicface of the proposed helix on the opposite face to the Ca D12+ D1 binding site. As m&is locatedin a shallow groove with the key residues which form the proposed interaction site facing the lipidbilayer,这是可接受的groove may provide the PLN transmembrane helix with access to theinteraction site.3. Transgenic mice overexpressing monomeric, dominant-acting，highly inhibitory PLN mutants generated.他们exhibited impaired cardiac contractility andrelaxation。

Phospholamban (PLN), an integral membrane protein of cardiac sarcoplasmic reticulum, reversibly inhibits the CaィイD12+ィエD1-ATPase (SERCA) to play a pivotal role in the regulation of cardiac contractility and relaxation. We examined the molecular mechanism of SERCA inhibition by PLN and we have created transgenic mice in which the dominant, highly inhibitory PLN mutant proteins are overexpressed in collaboration with Dr. D. H. MacLennan of the University of Toronto. Our results are following :1. PLN interacts with SERCA through at least two, possibly three sites ; cytoplasmic domain (domain Ia), transmembrane helix (domain II), and cytoplasmic-membrane boundary (domain Ib). Intramembrane interactions are inhibitory on SERCA activity, while the cytoplasmic interactions are not inhibitory itself although it is essential for the physiological regulatory effect. We propose that PLN and SERCA interact via a four base circuit through which long range inhibitory interactions night be propagated among a series of cytoplasmic and transmembrane interaction sites.2. PLN transmembrane domain interacts with the transmembrane sequence (M6) of SERCA. The interaction site consists of four residues which form the hydrophobic face of the proposed helix on the opposite face to the CaィイD12+ィエD1 binding site. As M& is located in a shallow groove with the key residues which form the proposed interaction site facing the lipid bilayer, it is conceivable that the groove may provide the PLN transmembrane helix with access to the interaction site.3. Transgenic mice overexpressing monomeric, dominant-acting, highly inhibitory PLN mutants were generated. They exhibited impaired cardiac contractility and relaxation.