The Ethanol Extract of Juk-Yeo, Bambusae Caulis in Taeniam, Decreases the Intracellular Levels of Lamins, Structural Nuclear Proteins of Lamina

Juk-Yeo (JY: 竹茹), an extract of the inner bark of Phyllostachys nigra var. henosis (Milford) Rendle (Poaceae), has been prescribed to clear heat and resolve phlegm in traditional Korean medicine, suggesting that JY has anti-inflammatory activity. While studying how JY regulates inflammation, we encountered unexpected findings regarding JY. Here, we provide evidence that JY decreased the intracellular levels of lamin B1, lamin B2, and A-type lamins. When treated with JY, A549 cells showed a reduced level of lamin B1 without altering the expression of YY1 and histone H3, well-documented nuclear proteins. Confocal analysis revealed that JY decreased lamin B1 in the nucleoplasm. Western blot analyses showed that JY could lower lamin B1 in many other cell types. As evidenced by RT-PCR analyses of lamin B1 mRNA and by unresponsiveness to protease inhibitors, such as E64d/PepA or MG132, JY neither blocks mRNA synthesis nor enhances protein degradation of lamin B1. Lamin B1 was under-detectable in exosomes, an extracellular vesicle that harbors various RNAs and proteins to be excreted. However, an anti-lamin B1 antibody precipitated lamin B1 in the media, in which JY-treated cells were cultured. Collectively, our findings suggest that JY excretes lamin B1 from cells, resulting in the decreased level of lamin B1. Lamins are part of the structural protein, providing the integrity of the nuclear membrane. Since abnormalities in lamins are found among the aged and in patients with rare diseases including Hutchinson-Gilford Progeria Syndrome (HGPS) and Emery-Dreifuss Muscular Dystrophy (EDMD), our results suggest that JY can be explored as therapeutics to ease symptoms associated with aging or lamin disorders.