Subunit 3 of the COP9 Signalosome Is Poised to Facilitate Communication between the Extracellular Matrix and the Nucleus through the Muscle-Specific β1D Integrin

Abstract

Yeast two-hybrid analysis (Fields and Song, , Nature, 340:245–246) was used to screen a human heart library to isolate proteins interacting with the adult muscle-specific β1D integrin but not with β1A integrin. In addition to previously identified interactions (RACK 1(Liliental and Chang, , Journal of Biological Chemistry, 273:2379–2383) and α-actinin (Otey et al., , Journal of Cell Biology, 111:721–729), the authors isolated several novel candidates. These include subunit 3 (CSN3/Sgn3) of the COP9 signalosome complex, cyclins D1, D2, and D3, RanBPM, and a recently identified protein COG8/DOR1. These protein interactions were specific for β1D integrin, as no binding to β1A integrin cytoplasmic domain was measurable by two-hybrid analysis. This paper presents the initial characterization of the interaction of CSN3 with β1D integrin, the localization of CSN3 and the other COP9 signalosome subunits in embryonic and adult cardiac myocytes and their response to muscle cell differentiation.

• β1D integrin
• COP9 signalosome
• CSN3
• heart