RNA type III secretion signals that require Hfq.

Salmonella virulence is largely mediated by two type III secretion systems (T3SS) that deliver effector proteins from the bacterium to a host cell; however, the secretion signal is poorly defined. Effector N termini are thought to contain the signal, but they lack homology, possess no identifiable motif, and adopt intrinsically disordered structures. Alternative studies suggest that RNA-encoded signals may also be recognized and that they can be located in the 5' untranslated leader sequence. We began our study by establishing the minimum sequence required for reporter translocation. Untranslated leader sequences predicted from 42 different Salmonella effector proteins were fused to the adenylate cyclase reporter (CyaA'), and each of them was tested for protein injection into J774 macrophages. RNA sequences derived from five effectors, gtgA, cigR, gogB, sseL, and steD, were sufficient for CyaA' translocation into host cells. To determine the mechanism of signal recognition, we identified proteins that bound specifically to the gtgA RNA. One of the unique proteins identified was Hfq. Hfq had no effect upon the translocation of full-length CigR and SteD, but injection of intact GtgA, GogB, and SseL was abolished in an hfq mutant, confirming the importance of Hfq. Our results demonstrated that the Salmonella pathogenicity island 2 (SPI-2) T3SS assembled into a functional apparatus independently of Hfq. Since particular effectors required Hfq for translocation, Hfq-RNA complexes may participate in signal recognition.

Brain Metastases from Endometrial Cancer: Clinical Characteristics, Outcomes, and Review of the Literature.

BACKGROUND: Brain metastases from endometrial cancer are rare and poorly described. We aimed to estimate the proportion of brain metastases at our institution that arose from endometrial cancer, and to detail clinicopathologic features and survival outcomes. METHODS: We retrospectively identified and reviewed the charts of 30 patients with brain metastases from endometrial cancer seen at Stanford Hospital from 2008 to 2018. RESULTS: Among all patients with brain metastases, the proportion arising from endometrial cancer was 0.84%. The median age at diagnosis was 62 years (range, 39-79 years), and the median overall survival from brain metastasis diagnosis was 6.8 months (range, 1.0-58.2 months). Most patients harbored endometrioid histology (53.3%), and some had concurrent metastases to lung (50.0%), bone (36.7%), and liver (20.0%). The median time from endometrial cancer diagnosis to brain metastasis development was 20.8 months (range, 1.4 months to 11.2 years), and the median number of brain metastases was 2 (range, 1-20). Patients with non-endometrioid histologies had more brain metastases than those with endometrioid histology (6.21 vs. 2.44, P = 0.029). There was no difference in overall survival by histology. CONCLUSIONS: We describe the largest cohort to date of patients with brain metastases originating from endometrial cancer. These patients represent a small fraction of all patients with brain metastases and have poor prognoses. These data enable providers caring for patients with brain metastases from endometrial cancer to appropriately counsel their patients.

Competitive binding of E3 ligases TRIM26 and WWP2 controls SOX2 in glioblastoma.

The pluripotency transcription factor SOX2 is essential for the maintenance of glioblastoma stem cells (GSC), which are thought to underlie tumor growth, treatment resistance, and recurrence. To understand how SOX2 is regulated in GSCs, we utilized a proteomic approach and identified the E3 ubiquitin ligase TRIM26 as a direct SOX2-interacting protein. Unexpectedly, we found TRIM26 depletion decreased SOX2 protein levels and increased SOX2 polyubiquitination in patient-derived GSCs, suggesting TRIM26 promotes SOX2 protein stability. Accordingly, TRIM26 knockdown disrupted the SOX2 gene network and inhibited both self-renewal capacity as well as in vivo tumorigenicity in multiple GSC lines. Mechanistically, we found TRIM26, via its C-terminal PRYSPRY domain, but independent of its RING domain, stabilizes SOX2 protein by directly inhibiting the interaction of SOX2 with WWP2, which we identify as a bona fide SOX2 E3 ligase in GSCs. Our work identifies E3 ligase competition as a critical mechanism of SOX2 regulation, with functional consequences for GSC identity and maintenance.

TERT, a promoter of CNS malignancies.

As cells replicate their DNA during mitosis, telomeres are shortened due to the inherent limitations of the DNA replication process. Maintenance of telomere length is critical for cancer cells to overcome cellular senescence induced by telomere shortening. Telomerase reverse transcriptase (TERT) is the rate-limiting catalytic subunit of telomerase, an RNA-dependent DNA polymerase that lengthens telomeric DNA to maintain telomere homeostasis. TERT promoter mutations, which result in the upregulation of TERT transcription, have been identified in several central nervous system (CNS) tumors, including meningiomas, medulloblastomas, and primary glial neoplasms. Furthermore, TERT promoter hypermethylation, which also results in increased TERT transcription, has been observed in ependymomas and pediatric brain tumors. The high frequency of TERT dysregulation observed in a variety of high-grade cancers makes telomerase activity an attractive target for developing novel therapeutics. In this review, we briefly discuss normal telomere biology, as well as the structure, function, and regulation of TERT in normal human cells. We also highlight the role of TERT in cancer biology, focusing on primary CNS tumors. Finally, we summarize the clinical significance of TERT promoter mutations in cancer, the molecular mechanisms through which these mutations promote oncogenesis, and recent advances in cancer therapies targeting TERT.

Radiological and clinical associations with scoliosis outcomes after posterior fossa decompression in patients with Chiari malformation and syrinx from the Park-Reeves Syringomyelia Research Consortium.

OBJECTIVE: In patients with Chiari malformation type I (CM-I) and a syrinx who also have scoliosis, clinical and radiological predictors of curve regression after posterior fossa decompression are not well known. Prior reports indicate that age younger than 10 years and a curve magnitude < 35° are favorable predictors of curve regression following surgery. The aim of this study was to determine baseline radiological factors, including craniocervical junction alignment, that might predict curve stability or improvement after posterior fossa decompression. METHODS: A large multicenter retrospective and prospective registry of pediatric patients with CM-I (tonsils ≥ 5 mm below the foramen magnum) and a syrinx (≥ 3 mm in width) was reviewed for clinical and radiological characteristics of CM-I, syrinx, and scoliosis (coronal curve ≥ 10°) in patients who underwent posterior fossa decompression and who also had follow-up imaging. RESULTS: Of 825 patients with CM-I and a syrinx, 251 (30.4%) were noted to have scoliosis present at the time of diagnosis. Forty-one (16.3%) of these patients underwent posterior fossa decompression and had follow-up imaging to assess for scoliosis. Twenty-three patients (56%) were female, the mean age at time of CM-I decompression was 10.0 years, and the mean follow-up duration was 1.3 years. Nine patients (22%) had stable curves, 16 (39%) showed improvement (> 5°), and 16 (39%) displayed curve progression (> 5°) during the follow-up period. Younger age at the time of decompression was associated with improvement in curve magnitude; for those with curves of ≤ 35°, 17% of patients younger than 10 years of age had curve progression compared with 64% of those 10 years of age or older (p = 0.008). There was no difference by age for those with curves > 35°. Tonsil position, baseline syrinx dimensions, and change in syrinx size were not associated with the change in curve magnitude. There was no difference in progression after surgery in patients who were also treated with a brace compared to those who were not treated with a brace for scoliosis. CONCLUSIONS: In this cohort of patients with CM-I, a syrinx, and scoliosis, younger age at the time of decompression was associated with improvement in curve magnitude following surgery, especially in patients younger than 10 years of age with curves of ≤ 35°. Baseline tonsil position, syrinx dimensions, frontooccipital horn ratio, and craniocervical junction morphology were not associated with changes in curve magnitude after surgery.

Radiological and clinical predictors of scoliosis in patients with Chiari malformation type I and spinal cord syrinx from the Park-Reeves Syringomyelia Research Consortium.

OBJECTIVE: Scoliosis is frequently a presenting sign of Chiari malformation type I (CM-I) with syrinx. The authors' goal was to define scoliosis in this population and describe how radiological characteristics of CM-I and syrinx relate to the presence and severity of scoliosis. METHODS: A large multicenter retrospective and prospective registry of pediatric patients with CM-I (tonsils ≥ 5 mm below the foramen magnum) and syrinx (≥ 3 mm in axial width) was reviewed for clinical and radiological characteristics of CM-I, syrinx, and scoliosis (coronal curve ≥ 10°). RESULTS: Based on available imaging of patients with CM-I and syrinx, 260 of 825 patients (31%) had a clear diagnosis of scoliosis based on radiographs or coronal MRI. Forty-nine patients (5.9%) did not have scoliosis, and in 516 (63%) patients, a clear determination of the presence or absence of scoliosis could not be made. Comparison of patients with and those without a definite scoliosis diagnosis indicated that scoliosis was associated with wider syrinxes (8.7 vs 6.3 mm, OR 1.25, p < 0.001), longer syrinxes (10.3 vs 6.2 levels, OR 1.18, p < 0.001), syrinxes with their rostral extent located in the cervical spine (94% vs 80%, OR 3.91, p = 0.001), and holocord syrinxes (50% vs 16%, OR 5.61, p < 0.001). Multivariable regression analysis revealed syrinx length and the presence of holocord syrinx to be independent predictors of scoliosis in this patient cohort. Scoliosis was not associated with sex, age at CM-I diagnosis, tonsil position, pB-C2 distance (measured perpendicular distance from the ventral dura to a line drawn from the basion to the posterior-inferior aspect of C2), clivoaxial angle, or frontal-occipital horn ratio. Average curve magnitude was 29.9°, and 37.7% of patients had a left thoracic curve. Older age at CM-I or syrinx diagnosis (p < 0.0001) was associated with greater curve magnitude whereas there was no association between syrinx dimensions and curve magnitude. CONCLUSIONS: Syrinx characteristics, but not tonsil position, were related to the presence of scoliosis in patients with CM-I, and there was an independent association of syrinx length and holocord syrinx with scoliosis. Further study is needed to evaluate the nature of the relationship between syrinx and scoliosis in patients with CM-I.

Erratum to stem nourished by branches: glioblastomas co-opt classic neurotrophic factor signaling to maintain stem-like cell pool.

[This corrects the article DOI: 10.21037/sci.2018.07.01.].