Birt-Hogg-Dubé syndrome, a hamartoma disorder characterized by benign tumors of the hair follicle, lung cysts, and renal neoplasia, is caused by germ-line mutations in the BHD(FLCN) gene, which encodes a tumor-suppressor protein, folliculin (FLCN), with unknown function. The tumor-suppressor proteins encoded by genes responsible for several other hamartoma syndromes, LKB1, TSC1͞2, and PTEN, have been shown to be involved in the mammalian target of rapamycin (mTOR) signaling pathway. Here, we report the identification of the FLCN-interacting protein, FNIP1, and demonstrate its interaction with 5 AMP-activated protein kinase (AMPK), a key molecule for energy sensing that negatively regulates mTOR activity. FNIP1 was phosphorylated by AMPK, and its phosphorylation was reduced by AMPK inhibitors, which resulted in reduced FNIP1 expression. AMPK inhibitors also reduced FLCN phosphorylation. Moreover, FLCN phosphorylation was diminished by rapamycin and amino acid starvation and facilitated by FNIP1 overexpression, suggesting that FLCN may be regulated by mTOR and AMPK signaling. Our data suggest that FLCN, mutated in Birt-Hogg-Dubé syndrome, and its interacting partner FNIP1 may be involved in energy and͞or nutrient sensing through the AMPK and mTOR signaling pathways.hamartoma syndrome ͉ renal cancer ͉ Birt-Hogg-Dubé ͉ tumor suppressor B irt-Hogg-Dubé (BHD) syndrome predisposes patients to develop hair follicle hamartomas, lung cysts, and an increased risk for renal neoplasia (1-3). BHD patients develop bilateral, multifocal renal tumors with a variety of histologies (4). We mapped the BHD locus to chromosome 17p11.2 by linkage analysis in BHD kindreds (5, 6) and identified germ-line mutations in a gene with unknown function that is highly conserved (7,8). Twenty-two unique mutations predicted to truncate the BHD protein folliculin (FLCN), including a ''hot spot'' insertion͞deletion in a C 8 tract, were identified in 84% of BHD kindreds (9). Somatic ''second-hit'' mutations identified in BHD-associated renal tumors suggest a tumor-suppressor function for FLCN (10), underscored by loss of BHD mRNA expression in renal tumors from BHD patients (11).Recent studies suggest that several hamartoma syndromes may be linked through the convergent energy͞nutrient-sensing pathways involved in mammalian target of rapamycin (mTOR) regulation (12-15). These inherited syndromes are characterized by multiple hamartomas and an increased risk of cancer. Germ-line mutations have been identified in four causative genes: LKB1, responsible for Peutz-Jeghers syndrome (16-18), TSC1 and TSC2, responsible for tuberous sclerosis complex (TSC) (19), and PTEN, responsible for Cowden syndrome (20). Loss of gene function leads to dysregulation of mTOR, which regulates cell growth and size through stimulation of protein synthesis (15, 21, 22).BHD syndrome, also a hamartoma disorder, displays phenotypic similarities to TSC that have led to speculation that BHD may function in the pathway(s) signaling through mTOR (12,23). To ascertain FLCN function,...

Birt-Hogg-Dubé syndrome ͉ kidney cancer ͉ mouse model ͉ mTOR ͉ tumor suppressor B irt-Hogg-Dubé (BHD) syndrome is an inherited kidney cancer syndrome which predisposes patients to develop hair follicle tumors, lung cysts, spontaneous pneumothorax, and an increased risk of renal neoplasia (1-3). We previously identified germline mutations in the BHD (FLCN) gene in patients with BHD (4). About one-third of BHD patients develop bilateral multifocal renal tumors that are most frequently chromophobe renal tumors and renal oncocytic hybrid tumors with features of chromophobe renal carcinoma and renal oncocytoma (5). Somatic mutations in the wild-type copy of BHD and loss of heterozygosity at chromosome 17p11.2 have been identified in human BHD tumors, indicating that BHD is a classical tumor suppressor gene (6). The BHD protein folliculin (FLCN) is a 64-kDa protein with no known functional domains (4). We reported two FLCN binding proteins FNIP1 and FNIP2, which interact with 5Ј-AMP-activated protein kinase (AMPK), an important energy sensor in cells that negatively regulates mammalian target of rapamycin (mTOR), the master switch for cell growth and proliferation (7-9). These findings suggest that FLCN may play a role in cellular energy and nutrient sensing through interactions with the AMPK-mTOR signaling pathway. Mutations in several other tumor suppressor genes, including LKB1 (10), PTEN (11), and TSC1/2 (12), have been shown to lead to dysregulation of PI3K-AKT-mTOR signaling and to the development of other hamartoma syndromes. We and others previously reported the generation of a conditionally targeted BHD allele and kidney-directed BHD inactivation in the mouse using the cadherin16 (KSP)-Cre transgene (13,14). Although BHD homozygous deletion in kidney epithelial cells was sufficient to cause uncontrolled cell proliferation and hyperplastic cell transformation, the kidney-targeted BHD-knockout mice lived only approximately 3 weeks and did not produce kidney tumors. A BHD heterozygous knockout mouse model that develops tumors with age will more accurately reflect tumor development in the human BHD patient and may be a better model for understanding how BHD inactivation leads to tumor initiation and progression. Here we report the analysis of an embryonic lethal phenotype that occurs in a BHD homozygous knockout mouse model and characterize and compare the kidney tumors that develop in a BHD heterozygous knockout mouse model with human BHD kidney tumors. ResultsRole of BHD during Early Embryogenesis. We have analyzed mouse BHD mRNA expression levels by qRT-PCR in wild-type embryos and adult tissues (Fig. S1). We detected consistent BHD mRNA expression from E8.5 to E12.5 with 4-fold elevation at E19 and high expression in adult heart, pancreas, and prostate with moderate expression in adult brain, kidney, liver, and lung. BHD mRNA expression was further analyzed during early embryogenesis by whole mount in situ hybridization (Fig. S2). BHD mRNA was expressed consistently throughout embryogenesis. At E5.5, BHD expr...

The taxonomy of Aspergillus section Fumigati with its teleomorph genus Neosartorya is revised. The species concept is based on phenotypic (morphology and extrolite profiles) and molecular (β-tubulin and calmodulin gene sequences) characters in a polyphasic approach. Four new taxa are proposed: N. australensis N. ferenczii, N. papuaensis and N. warcupii. All newly described and accepted species are illustrated. The section consists of 33 taxa: 10 strictly anamorphic Aspergillus species and 23 Neosartorya species. Four other Neosartorya species described previously were not available for this monograph, and consequently are relegated to the category of doubtful species.