Search

The glycoprotein Prominin-1 and the carbohydrate Lewis X stage-specific embryonic antigen 1 (LeX-SSEA1) both have been extensively used as cell surface markers to purify neural stem cells (NSCs). While Prominin-1 labels a specialized membrane region in NSCs and ependymal cells, the specificity of LeX-SSEA1 expression and its biological significance are still unknown. To address these issues, we have here monitored the expression of the carbohydrate in neonatal and adult NSCs and in their progeny. Our results show that the percentage of immunopositive cells and the levels of LeX-SSEA1 immunoreactivity both increase with postnatal age across all stages of the neural lineage. This is associated with decreased proliferation in precursors including NSCs, which accumulate the carbohydrate at the cell surface while remaining quiescent. Exposure of precursors to bone morphogenetic protein (BMP) increases LEX-SSEA1 expression, which promotes cell cycle withdrawal by a mechanism involving LeX-SSEA1-mediated interaction at the cell surface. Conversely, interference with either BMP signaling or with LeX-SSEA1 promotes proliferation to a similar degree. Thus, in the postnatal germinal niche, the expression of LeX-SSEA1 increases with age and exposure to BMP signaling, thereby downregulating the proliferation of subependymal zone precursors including NSCs.

BRCA1/2 variants are prognostic biomarkers for hereditary breast and/or ovarian cancer (HBOC) syndrome and predictive biomarkers for PARP inhibition. In this study, we benchmarked the classification of BRCA1/2 variants from patients with HBOC-related cancer using MH BRCA, a novel computational technology that combines the ACMG guidelines with expert-curated variant annotations. Evaluation of BRCA1/2 variants (n = 1040) taken from four HBOC studies showed strong concordance within the pathogenic (98.1%) subset. Comparison of MH BRCA&rsquo, s ACMG classification to ClinVar submitter content from ENIGMA, the international consortium of investigators on the clinical significance of BRCA1/2 variants, the ARUP laboratories, a clinical testing lab of the University of UTAH, and the German Cancer Consortium showed 99.98% concordance (4975 out of 4976 variants) in the pathogenic subset. In our patient cohort, refinement of patients with variants of unknown significance reduced the uncertainty of cancer-predisposing syndromes by 64.7% and identified three cases with potential family risk to HBOC due to a likely pathogenic variant BRCA1 p.V1653L (NM_007294.3:c.4957G &gt, T, rs80357261). To assess whether classification results predict PARP inhibitor efficacy, contextualization with functional impact information on DNA repair activity were performed, using MH Guide. We found a strong correlation between treatment efficacy association and MH BRCA classifications. Importantly, low efficacy to PARP inhibition was predicted in 3.95% of pathogenic variants from four examined HBOC studies and our patient cohort, indicating the clinical relevance of the consolidated variant interpretation.

Imprinted genes play a critical role in brain development and mental health, although the underlying molecular and cellular mechanisms remain incompletely understood. The family of basic helix-loop-helix (bHLH) proteins directs the proliferation, differentiation, and specification of distinct neuronal progenitor populations. Here, we identified the bHLH factor gene Tcf4 as a direct target gene of Zac1/Plagl1, a maternally imprinted transcriptional regulator, during early neurogenesis. Zac1 and Tcf4 expression levels concomitantly increased during neuronal progenitor differentiation; moreover, Zac1 interacts with two cis-regulatory elements in the Tcf4 gene locus, and these elements together confer synergistic activation of the Tcf4 gene. Tcf4 upregulation enhances the expression of the cyclin-dependent kinase inhibitor gene p57(Kip2), a paternally imprinted Tcf4 target gene, and increases the number of cells in G1 phase. Overall, we show that Zac1 controls cell cycle arrest function in neuronal progenitors through induction of p57(Kip2) via Tcf4 and provide evidence for cooperation between imprinted genes and a bHLH factor in early neurodevelopment.

Background The BRCA1/2 genes have emerged as critical biomarkers, particularly for patients with hereditary breast and ovarian cancer (HBOC). MH BRCA classifies variants based on ACMG guidelines. Clinical interpretation of NGS results by MH GUIDE provides clinicians with treatment recommendations to cancer based on expert curated biomarker knowledge. Methods MH BRCA was compared to the clinical interpretation of three Japanese HBOC studies. Population-frequency (PF) data from the 1000 Genomes Project (1000G) and the Japanese genome cohort of Tohoku Medical Megabank Organization (ToMMo) were analyzed. Based on functional evidence for DNA damage response, we correlated the ACMG index with the predicted response to PARP inhibition by MH GUIDE. Finally, BRCA classifications of 350 patients with breast and/or ovarian cancer sequenced at the Yamanashi Central Hospital (YPCH) were compared to MH BRCA. Results MH BRCA using the integrated ToMMo data revealed 40% increased accuracy in benign classification. The Japanese-cohort in 1000G represents Conclusion We enhanced the performance of MH BRCA for Japanese HBOC patients by integrating data from the ToMMo database. Our collaboration with YPCH revealed that MH BRCA supports a standardized process for assessment of pathogenicity. Contextualizing of MH BRCA classifications with MH GUIDE supports the treatment strategy of PARP inhibition with the benefit on fine-resolution of hypermorphic and hypomorphic BRCA mutations.

Cell-fate decisions and differentiation of embryonic and adult neural stem cells (NSC) are tightly controlled by lineage-restricted and temporal factors that interact with cell-intrinsic programs and extracellular signals through multiple regulatory loops. Imprinted genes are important players in neurodevelopment and mental health although their molecular and cellular functions remain poorly understood. Here, we show that the paternally expressed transcriptional regulator Zac1 (zinc finger protein regulating apoptosis and cell cycle arrest) is transiently induced during astroglial and neuronal differentiation of embryonic and adult NSC lines. Thereby, Zac1 transactivates Socs3 (suppressor of cytokine signaling 3), a potent inhibitor of prodifferentiative Jak/Stat3 signaling, in a lineage-specific manner to prevent precocious astroglial differentiation. In vivo, Zac1 and Socs3 colocalize in the neocortical ventricular zone during incipient astrogliogenesis. Zac1 overexpression in primary NSCs delays astroglial differentiation whereas knockdown of Zac1 or Socs3 facilitates formation of astroglial cells. This negative feedback loop is unrelated to Zac1′s cell cycle arrest function and specific to the Jak/Stat3 pathway. Hence, reinstating Jak/Stat3 signaling in the presence of increased Zac1 expression allows for timely astroglial differentiation. Overall, we suggest that the imprinted gene Zac1 curtails astroglial differentiation of NSCs in the developing and adult brain.