Metastasis is the leading cause of treatment failure in medulloblastoma. Understanding the genetic regulation of metastasis may aid in the development of novel treatments. We therefore performed in ...silico analysis of the mRNA expression of 83 medulloblastomas compiled from two independent microarray studies by focusing on 135 genes most frequently linked to metastasis in other tumors. We then asked whether expression of these genes correlated with metastasis in the medulloblastoma array data sets. We found the platelet-derived growth factor receptor alpha, early growth response protein 1 and insulin-like growth factor 2 genes as well as several genes associated with MYCC and ERBB2 overexpressed by at least 2-fold in metastatic tumors in both array data sets. We conclude that these genes may interact to promote prometastatic signaling in medulloblastoma.
HIC1 (hypermethylated in cancer 1) is a tumor suppressor gene located at chromosome 17p13.3, a region frequently hypermethylated or deleted in human tumors and in a contiguous-gene syndrome, the ...Miller-Dieker syndrome. HIC1 is a transcriptional repressor containing five Krüppel-like C2H2 zinc fingers and an N-terminal dimerization and autonomous repression domain called BTB/POZ. Although some of the HIC1 transcriptional repression mechanisms have been recently deciphered, target genes are still to be discovered. In this study, we determined the consensus binding sequence for HIC1 and investigated its DNA binding properties. Using a selection and amplification of binding sites technique, we identified the sequence 5′-C/GNGC/GGGGCAC/A CC-3′ as an optimal binding site. In silico and functional analyses fully validated this consensus and highlighted a GGCA core motif bound by zinc fingers 3 and 4. The BTB/POZ domain inhibits the binding of HIC1 to a single site but mediates cooperative binding to a probe containing five concatemerized binding sites, a property shared by other BTB/POZ proteins. Finally, full-length HIC1 proteins transiently expressed in RK13 cells and more importantly, endogenous HIC1 proteins from the DAOY medulloblastoma cell line, repress the transcription of a reporter gene through their direct binding to these sites, as confirmed by chromatin immunoprecipitation experiments. The definition of the HIC1-specific DNA binding sequence as well as the requirement for multiple sites for optimal binding of the full-length protein are mandatory prerequisites for the identification and analyses of bona fide HIC1 target genes.
DNA methylation and epigenetic inactivation of the
O
6
-methylguanine methyltransferase (
MGMT
) gene induces MGMT deficiency, reducing the tumor cell’s DNA repair capacity and increasing its ...susceptibility to alkylating chemotherapeutic agents. Consequently, adult patients whose tumors are deficient in MGMT have better outcomes with alkylator chemotherapy, and
MGMT
methylation has been proposed as a screening marker of deficient tumors. In order to test the feasibility of this approach for medulloblastoma, a common brain tumor in children, we determined the methylation status, mRNA expression pattern, and protein expression of MGMT in a panel of clinical specimens. Methylation-specific polymerase chain reaction analysis revealed methylation of
MGMT
in 28 of 37 tumor samples. Quantitative real-time reverse transcriptase–polymerase chain reaction showed a range of expression of
MGMT
mRNA varying more than 20-fold. However, there was no correlation found between
MGMT
methylation and mRNA expression. Immunohistochemistry demonstrated that all tumors were immunoreactive for MGMT in the nucleus of the medulloblastoma cells in a heterogeneous pattern. The intercell variability of MGMT complement explained the discordance between methylation and expression. Therefore,
MGMT
methylation as determined by methylation-specific polymerase chain reaction cannot be used as a marker for MGMT deficiency in medulloblastoma. Further, these findings support the use of pharmacological MGMT depletion as a rational approach for intensification of alkylator chemotherapy in the treatment of medulloblastoma.
Minority individuals might conceal their identity in social contexts in an effort to avoid stigma and victimization. Unfortunately, identity concealment is thought to impact psychological distress in ...transgender and gender nonconforming (TGNC) individuals. Thus, through 30 in-depth interviews, we sought to understand if and how identity concealment was experienced by TGNC individuals. Findings indicated that (a) TGNC identity concealment is a source of stress, (b) individuals might conceal their TGNC identity based on social context, (c) concealment of assigned sex and gender history can function to affirm one's true gender identity, and (d) concealment of gender history is a rejection of one's assigned sex. In addition, (a) passing/blending is an important interpersonal and intrapersonal process, (b) the importance of passing/blending can change over time, and (c) not passing/blending may result in worrying about personal safety. The authors discuss how concealment can both inhibit and promote psychological health for TGNC individuals, and they offer clinical applications for health providers.
Public Policy Relevance Statement
Concealing one's transgender identity appears to be associated with psychological distress; however, concealing one's assigned physical body and gender history might function to affirm one's true gender. Thus, policymakers in different social contexts-schools, employment, health care-should work to promote transgender inclusivity and create supportive settings where transgender individuals can affirm their true gender without fear of retribution.
Purpose:
Transgender and gender-nonconforming (TGNC) individuals often are the target of enacted or external (i.e., distal) experiences of stigma, discrimination, and violence, which are linked to ...adverse health, particularly psychological distress. There is limited research, however, examining felt or internal (i.e., proximal) stressors faced by TGNC individuals. This study sought to examine one type of internal stressor,
expecting rejection
, and aimed to (1) identify how and to what extent rejection expectations operate day-to-day for TGNC individuals and (2) explore how TGNC individuals respond to expectations of rejection.
Methods:
In-depth interviews were conducted with 30 participants from 2014 to 2015 who identified as TGNC (mean age=30.4; 60% people of color); data were analyzed using a consensual qualitative research method.
Results:
Four thematic categories emerged about expecting rejection: (1) where to expect rejection; (2) thoughts and feelings associated with expectations of rejection; (3) coping strategies used to manage the expectation of rejection; and (4) the intersection of race and ethnicity with rejection expectations.
Conclusion:
Findings from this study suggest that expecting rejection is a frequent and salient internal stressor for TGNC individuals. We discuss the psychological and cumulative potential health impact of minority stress, and the applicability of Meyer's Minority Stress Model. Therapeutic interventions are needed to address the specific cognitive, emotional, and behavioral responses TGNC individuals experience as a result of the stress associated with expecting rejection, including fear, anxiety, and situational avoidance.
Stable isotope-resolved metabolomics (SIRM) provides information regarding the relative activity of numerous metabolic pathways and the contribution of nutrients to specific metabolite pools; ...however, SIRM experiments can be difficult to execute, and data interpretation is challenging. Furthermore, standardization of analytical procedures and workflows remain significant obstacles for widespread reproducibility. Here, we demonstrate the workflow of a typical SIRM experiment and suggest experimental controls and measures of cross-validation that improve data interpretation. Inhibitors of glycolysis and oxidative phosphorylation as well as mitochondrial uncouplers serve as pharmacological controls, which help define metabolic flux configurations that occur under well-controlled metabolic states. We demonstrate how such controls and time course labeling experiments improve confidence in metabolite assignments as well as delineate metabolic pathway relationships. Moreover, we demonstrate how radiolabeled tracers and extracellular flux analyses integrate with SIRM to improve data interpretation. Collectively, these results show how integration of flux methodologies and use of pharmacological controls increase confidence in SIRM data and provide new biological insights.
GOES-R series spacecraft feature a number of flexible appendages with modal frequencies below 3.0 Hz which, if excited by spacecraft disturbances, can be sources of undesirable jitter perturbing ...spacecraft pointing. In order to meet GOES-R pointing stability requirements, the spacecraft flight software implements an Active Vibration Damping (AVD) rate control law which acts in parallel with the nadir point attitude control law. The AVD controller commands spacecraft reaction wheel actuators based upon Inertial Measurement Unit (IMU) inputs to provide additional damping for spacecraft structural modes below 3.0 Hz which vary with solar wing angle. A GOES-R spacecraft dynamics and attitude control system identified model is constructed from pseudo-random reaction wheel torque commands and IMU angular rate response measurements occurring over a single orbit during spacecraft post-deployment activities. The identified Fourier model is computed on the ground, uplinked to the spacecraft flight computer, and the AVD controller filter coefficients are periodically computed on-board from the Fourier model. Consequently, the AVD controller formulation is based not upon pre-launch simulation model estimates but upon on-orbit nadir point attitude control and time-varying spacecraft dynamics. GOES-R high-fidelity time domain simulation results herein demonstrate the accuracy of the AVD identified Fourier model relative to the pre-launch spacecraft dynamics and control truth model. The AVD controller on-board the GOES-16 spacecraft achieves more than a ten-fold increase in structural mode damping of the fundamental solar wing mode while maintaining controller stability margins and ensuring that the nadir point attitude control bandwidth does not fall below 0.02 Hz. On-orbit GOES-16 spacecraft appendage modal frequencies and damping ratios are quantified based upon the AVD system identification, and the increase in modal damping provided by the AVD controller for each structural mode is presented. The GOES-16 spacecraft AVD controller frequency domain stability margins and nadir point attitude control bandwidth are presented along with on-orbit time domain disturbance response performance.
Transgender and gender diverse (TGD) individuals experience stigma related to their gender identity. However, little research has been conducted exploring how TGD individuals cope with, build ...resilience from, or obtain support concerning gender-related stress. In this study, we recruited TGD individuals (n = 30) to elucidate the coping strategies used in response to gender-related stress; to explore how they developed and maintained resilience; and to understand the impact of social support from others in navigating gender-related stressors. Participants completed individual, semistructured, qualitative interviews, which we coded using consensual qualitative research methods. Many participants underscored the strain of having to educate cisgender friends, family, and health care providers about TGD experiences. Participants endorsed using strategic avoidance or modulating their gender presentation to manage gender-related stress. Additionally, participants discussed various intragroup prosocial behaviors (i.e., developing TGD spaces) to sustain resilience and increase or maintain social support. Despite the expansive literature focused on TGD risk, most participants reported significant self-compassion and effective coping strategies for managing gender-related stress throughout their lives. Unique techniques described by our participants that are infrequently discussed in the coping literature on cisgender individuals (i.e., strategic avoidance and intragroup prosocial behaviors) echo those reported by other marginalized group members.
Public Significance Statement
The present study used consensual qualitative research methods to investigate coping and resilience in a sample of transgender and gender diverse (TGD) individuals. We advanced the understanding of how TGD individuals cope, and even thrive, despite the ubiquitous experience of gender-related stress. Possible implications emerged about ways to better support TGD individuals, both clinically and socially.
Hypoxia commonly occurs in solid tumors of the central nervous system (CNS) and often interferes with therapies designed to stop their growth. We found that pediatric high-grade glioma (HGG)-derived ...precursors showed greater expansion under lower oxygen tension, typical of solid tumors, than normal CNS precursors. Hypoxia inhibited p53 activation and subsequent astroglial differentiation of HGG precursors. Surprisingly, although HGG precursors generated endogenous bone morphogenetic protein (BMP) signaling that promoted mitotic arrest under high oxygen tension, this signaling was actively repressed by hypoxia. An acute increase in oxygen tension led to Smad activation within 30 minutes, even in the absence of exogenous BMP treatment. Treatment with BMPs further promoted astroglial differentiation or death of HGG precursors under high oxygen tension, but this effect was inhibited under hypoxic conditions. Silencing of hypoxia-inducible factor 1alpha (HIF1alpha) led to Smad activation even under hypoxic conditions, indicating that HIF1alpha is required for BMP repression. Conversely, BMP activation at high oxygen tension led to reciprocal degradation of HIF1alpha; this BMP-induced degradation was inhibited in low oxygen. These results show a novel, mutually antagonistic interaction of hypoxia-response and neural differentiation signals in HGG proliferation, and suggest differences between normal and HGG precursors that may be exploited for pediatric brain cancer therapy.
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