Identification and characterization of a novel folliculin-interacting protein FNIP2

• Published in: Gene Vol. 415; no. 1; pp. 60 - 67
• Main Authors: Hasumi, Hisashi, Baba, Masaya, Hong, Seung-Beom, Hasumi, Yukiko, Huang, Ying, Yao, Masahiro, Valera, Vladimir A., Linehan, W. Marston, Schmidt, Laura S.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 31.05.2008
• Subjects: Adenylate Kinase - metabolism; Amino Acid Sequence; AMPK; BHD; Carcinoma, Renal Cell - genetics; Carrier Proteins - chemistry; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cell Line; Evolution, Molecular; FLCN; FNIP1; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Humans; Kidney - metabolism; Kidney - pathology; Kidney Neoplasms - genetics; Molecular Sequence Data; Multiprotein Complexes - metabolism; Protein Binding; Protein Transport; Proto-Oncogene Proteins - genetics; Proto-Oncogene Proteins - metabolism; Renal cell carcinoma (RCC); RNA, Messenger - genetics; RNA, Messenger - metabolism; Sequence Homology, Nucleic Acid; Subcellular Fractions - enzymology; Tumor suppressor; Tumor Suppressor Proteins - genetics; Tumor Suppressor Proteins - metabolism; FLCN; qRT; RCC; mTOR; AMPK; GST; Renal cell carcinoma (RCC); FNIP1; FNIP2; Tumor suppressor; BHD; HEK
• ISSN: 0378-1119; 1879-0038
• DOI: 10.1016/j.gene.2008.02.022

Birt–Hogg–Dube' syndrome characterized by increased risk for renal neoplasia is caused by germline mutations in the BHD/FLCN gene encoding a novel tumor suppressor protein, folliculin(FLCN), which interacts with FNIP1 and 5′-AMP-activated protein kinase(AMPK). Here we report the identification and characterization of a novel FNIP1 homolog FNIP2 that also interacts with FLCN and AMPK. C-terminally-deleted FLCN mutants, similar to those produced by naturally-occurring germline mutations in BHD patients, were unable to bind FNIP2. These data taken together with our previous results that demonstrated FNIP1 binding to the C-terminus of FLCN suggest that FLCN tumor suppressor function may be facilitated by interactions with both FNIP1 and FNIP2 through its C-terminus. Furthermore, we demonstrate that FNIP1 and FNIP2 are able to form homo- or heteromeric multimers suggesting that they may function independently or cooperatively with FLCN. Differential expression of FNIP1 and FNIP2 transcripts in some normal tissues may indicate tissue specificity for these homologs. Interestingly FNIP1 and FNIP2 were oppositely expressed in human clear cell renal cell carcinoma (RCC), and coordinately expressed in chromophobe RCC and oncocytoma, suggesting their differential function in different histologic variants of RCC.