The ciliopathy Joubert syndrome is marked by cerebellar vermis hypoplasia, a phenotype for which the pathogenic mechanism is unclear1–3. In order to investigate Joubert syndrome pathogenesis, we have examined mice with mutated Ahi1, the first identified Joubert syndrome gene4,5. These mice exhibit cerebellar hypoplasia with a vermis/midline fusion defect early in development. This defect is concomitant with expansion of the roof plate and is also evident in a mouse mutant for another Joubert syndrome gene, Cep2906,7. Further, fetal magnetic resonance imaging (MRI) from human subjects with Joubert syndrome reveals a similar midline cleft suggesting parallel pathogenic mechanisms. Previous evidence has suggested a role for Jouberin (Jbn), the protein encoded by Ahi1, in canonical Wnt signaling8. Consistent with this, we found decreased Wnt reporter activity at the site of hemisphere fusion in the developing cerebellum of Ahi1 mutant mice. This decrease was accompanied by reduced proliferation at the site of fusion. Finally, treatment with lithium, a Wnt pathway agonist9, partially rescued this phenotype. Our findings implicate a defect in Wnt signaling in the cerebellar midline phenotype seen in Joubert syndrome, which can be overcome with Wnt stimulation.

Renal clear cell carcinoma (RCCC) is a malignant tumor with poor prognosis caused by the high incidence of metastasis to distal organs. Although metastatic RCCC cells frequently show aberrant cytoskeletal organization, the underlying mechanism has not been elucidated. DAL-1/4.1B is an actin-binding protein implicated in the cytoskeleton-associated processes, while its inactivation is frequently observed in lung and breast cancers and meningiomas, suggesting that 4.1B is a potential tumor suppressor. We studied a possible involvement of 4.1B in RCCCs and evaluated it as a clinical indicator. 4.1B protein was detected in the proximal convoluted tubules of human kidney, the presumed cell of origin of RCCC. On the other hand, loss or marked reduction of its expression was observed in 10 of 19 (53%) renal cell carcinoma (RCC) cells and 12 of 19 (63%) surgically resected RCCC by reverse transcription-PCR. Bisulfite sequencing or bisulfite SSCP analyses revealed that the 4.1B promoter was methylated in 9 of 19 (47%) RCC cells and 25 of 55 (45%) surgically resected RCCC, and inversely correlated with 4.1B expression (p < 0.0001). Aberrant methylation appeared to be a relatively early event because more than 40% of the tumors with pT1a showed hypermethylation. Furthermore, 4.1B methylation correlated with a nuclear grade (p 5 0.017) and a recurrence-free survival (p 5 0.0036) and provided an independent prognostic factor (p 5 0.038, relative risk 10.5). These results indicate that the promoter methylation of the 4.1B is one of the most frequent epigenetic alterations in RCCC and could predict the metastatic recurrence of the surgically resected RCCC. ' 2005 Wiley-Liss, Inc.Key words: tumor suppressor gene; bi-sulfite sequencing; two-hit inactivation; recurrence-free survival rate; independent prognostic factor Renal cell carcinoma (RCC) accounts for about 2% of human cancers worldwide, with an incidence of 189,000 and a mortality of 91,000 reported in the year of 2000. 1 Renal clear cell carcinoma (RCCC), which represents 75% of all RCC, exhibits frequent metastasis to distant organs without any clinical symptoms. Furthermore, 40-60% of RCCC tumors without metastasis at first presentation eventually develop metastasis as they progress. 2 Finally, metastatic RCCC becomes refractory to any therapeutic approaches, including chemo-, radio-, and hormonal therapies, resulting in a poor prognosis of patients, with a 5-year survival of less than 10%. 3 Thus, understanding the molecular mechanisms of the development and progression of RCCC is a critical issue for controlling this refractory cancer.Several genetic and epigenetic alterations have been reported in RCCC. The mutation of the VHL gene, associated with loss of heterozygosity (LOH) at the gene locus on chromosomal fragment 3p25-p26, was observed in~50% of sporadic RCCC. 4 Since the VHL encodes a component of an E3 ubiquitin ligase that promotes the degradation of hypoxia-inducible factors, loss of VHL function could be involved in angiogenesis, one of the most characteri...

Purpose: DAL-1/4.1B is an actin-binding protein originally identified as a molecule whose expression is down-regulated in lung adenocarcinoma.We have previously shown that a lung tumor suppressor,TSLC1, associates with DAL-1, suggesting that both proteins act in the same cascade.The purpose of this study is to understand the molecular mechanisms and clinical significance of DAL-1 inactivation in lung cancer. Experimental Design: We studied aberration of the DAL-1 in 103 primary non^small cell lung cancers (NSCLC) and 18 lung cancer cells. Expression and allelic and methylation status of DAL-1 was examined by reverse transcription-PCR, microsatellite analysis, and bisulfite sequencing or bisulfite single-strand conformational polymorphism, respectively. Results: Loss of DAL-1 expression was strongly correlated with promoter methylation in lung cancer cells, whereas DAL-1 expression was restored by a demethylating agent, 5-aza-2V-deoxycytidine. The DAL-1 promoter was methylated in 59 (57%) primary NSCLC tumors, 37% of which were associated with loss of heterozygosity around the DAL-1 on chromosomal region 18p11.3. In squamous cell carcinomas, DAL-1 methylation was observed in 9 of 10 tumors at stage I, whereas the incidence of methylation gradually increased in adenocarcinomas as they progressed [13 of 36 (36%), 4 of 12 (33%), 14 of 17 (82%), and 3 of 3 (100%) tumors at stages I, II, III, and IV, respectively; P = 0.0026]. Furthermore, in adenocarcinomas, disease-free survival and overall survival were significantly shorter in patients with tumors harboring the methylated DAL-1 (P = 0.0011and P = 0.045, respectively). Conclusions: DAL-1 methylation is involved in the development and progression of NSCLC and provides an indicator for poor prognosis.

TSLC1/IGSF4, an immunoglobulin superfamily molecule, is predominantly expressed in the brain, lungs, and testes and plays important roles in epithelial cell adhesion, cancer invasion, and synapse formation. We generated Tslc1/Igsf4-deficient mice by disrupting exon 1 of the gene and found that Tslc1 ؊/؊ mice were born with the expected Mendelian ratio but that Tslc1 ؊/؊ male mice were infertile. In 11-week-old adult Tslc1mice, the weight of a testis was 88% that in Tslc1 ؉/؉ mice, and the number of sperm in the semen was approximately 0.01% that in Tslc1 ؉/؉ mice. Histological analysis revealed that the round spermatids and the pachytene spermatocytes failed to attach to the Sertoli cells in the seminiferous tubules and sloughed off into the lumen with apoptosis in the Tslc1 ؊/؊ mice. On the other hand, the spermatogonia and the interstitial cells, including Leydig cells, were essentially unaffected. In the Tslc1 ؉/؉ mice, TSLC1/IGSF4 expression was observed in the spermatogenic cells from the intermediate spermatogonia to the early pachytene spermatocytes and from spermatids at step 7 or later. These findings suggest that TSLC1/IGSF4 expression is indispensable for the adhesion of spermatocytes and spermatids to Sertoli cells and for their normal differentiation into mature spermatozoa.