Keratin 8 and 18 (K8/18) are the major components of intermediate filament (IF) proteins of simple or single-layered epithelia. Recent data show that normal and malignant epithelial cells deficient in K8/18 are nearly 100 times more sensitive to tumor necrosis factor (TNF)–induced cell death. We have now identified human TNF receptor type 1 (TNFR1)–associated death domain protein (TRADD) to be the K18-interacting protein. Among IF proteins tested in two-hybrid systems, TRADD specifically bound K18 and K14, type I (acidic) keratins. The COOH-terminal region of TRADD interacted with the coil Ia of the rod domain of K18. Endogenous TRADD coimmunoprecipitated with K18, and colocalized with K8/18 filaments in human mammary epithelial cells. Overexpression of the NH2 terminus (amino acids 1–270) of K18 containing the TRADD-binding domain as well as overexpression of K8/18 in SW13 cells, which are devoid of keratins, rendered the cells more resistant to killing by TNF. We also showed that overexpressed NH2 termini of K18 and K8/18 were associated with endogenous TRADD in SW13 cells, resulting in the inhibition of caspase-8 activation. These results indicate that K18 may sequester TRADD to attenuate interactions between TRADD and activated TNFR1 and moderate TNF-induced apoptosis in simple epithelial cells.
Keratin attenuates tumor necrosis factor–induced cytotoxicity through association with TRADD
H. Inada, I. Izawa, and M. Nishizawa contributed equally to this work.
Abbreviations used in this paper: aa, amino acid(s); ACR, aclarubicin; CHX, cycloheximide; DISC, death-inducing signaling complex; EBNA, Epstein-Barr virus–associated nuclear antigen; FADD, Fas-associated death domain; GFAP, glial fibrillary acidic protein; GST, glutathione S-transferase; His, histidine; HMEC, human mammary epithelial cells; IF, intermediate filament; K8/18, keratin 8 and 18; NCS, neocarzinostatin; NF-κB, nuclear factor-κB; TNF, tumor necrosis factor; TNFR, TNF receptor; TRADD, TNFR1-associated death domain protein.
Hiroyasu Inada, Ichiro Izawa, Miwako Nishizawa, Eriko Fujita, Tohru Kiyono, Toshitada Takahashi, Takashi Momoi, Masaki Inagaki; Keratin attenuates tumor necrosis factor–induced cytotoxicity through association with TRADD . J Cell Biol 29 October 2001; 155 (3): 415–426. doi: https://doi.org/10.1083/jcb.200103078
Download citation file:
Sign in
Client Account
Sign in via your Institution
Sign in via your InstitutionEmail alerts
Advertisement
Advertisement