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Identification of RBMX as an ARTS‐1‐Associated Protein that Mediates Soluble TNFR1 Release
Author(s) -
Adamik Barbara,
Islam Aminul,
Hawari Feras,
Rouhani Farshid,
Yu ZuXi,
Combs Christian,
Zhang Jing,
Levine Stewart J
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a61-d
Subject(s) - identification (biology) , the arts , chemistry , medicine , biology , art , visual arts , botany
ARTS‐1 (Aminopeptidase Regulator of Type I TNF Receptor Shedding) is an integral membrane protein that binds to and promotes the release of soluble TNFR1. To identify novel ARTS‐1‐interacting proteins, we performed co‐immunoprecipitation experiments on NCI‐H292 cell membrane fractions using an anti‐ARTS‐1 antibody. RBMX, a 43‐kDa heterogeneous nuclear ribonucleoprotein, co‐immunoprecipitated with ARTS‐1 and was identified by SDS‐PAGE, and MALDI‐MS peptide mass mapping. Treatment of cell lysates with RNAse A and T1 significantly increased the co‐immunoprecipitation of endogenous RBMX and ARTS‐1, but did not alter the association between ARTS‐1 and TNFR1. This suggests that the majority of RBMX is sequestered by RNA under basal conditions, while the association between ARTS‐1 and TNFR1 is not dependent upon RNA. Confocal microscopy showed limited co‐localization of RBMX and ARTS‐1 within intracytoplasmic vesicular structures. HUVEC transfected with siRNA targeting RBMX showed a significant reduction of TNFR1 release into culture supernatants, as compared to cells transfected with control siRNA. Thus, we have identified RBMX as an ARTS‐1‐associated protein that plays an important role in the constitutive release of TNFR1 to the extracellular compartment. Funded by: DIR, NHLBI, NIH