The Neuron Navigators: Structure, function, and evolutionary history

Fine mapping and candidate gene analysis of Dravet syndrome modifier loci on mouse chromosomes 7 and 8

Dravet syndrome is a developmental and epileptic encephalopathy (DEE) characterized by intractable seizures, comorbidities related to developmental, cognitive, and motor delays, and a high mortality burden due to sudden unexpected death in epilepsy (SUDEP). Most Dravet syndrome cases are attributed to SCN1A haploinsufficiency, with genetic modifiers and environmental factors influencing disease severity. Mouse models with heterozygous deletion of Scn1a recapitulate key features of Dravet syndrome, including seizures and premature mortality; however, severity varies depending on genetic background. Here, we refined two Dravet survival modifier (Dsm) loci, Dsm2 on chromosome 7 and Dsm3 on chromosome 8, using interval-specific congenic (ISC) mapping. Dsm2 was complex and encompassed at least two separate loci, while Dsm3 was refined to a single locus. Candidate modifier genes within these refined loci were prioritized based on brain expression, strain-dependent differences, and biological relevance to seizures or epilepsy. High priority candidate genes for Dsm2 include Nav2, Ptpn5, Ldha, Dbx1, Prmt3 and Slc6a5, while Dsm3 has a single high priority candidate, Psd3. This study underscores the complex genetic architecture underlying Dravet syndrome and provides insights into potential modifier genes that could influence disease severity and serve as novel therapeutic targets.

Downregulation of miR-29a as a possible diagnostic biomarker for schizophrenia

BACKGROUND

MicroRNAs (miRNAs) are epigenetic factors regulating many genes involved in brain development. Dysregulation of miRNA could result in dysregulation of genes which may contribute to diseases affecting the brain and behavior (e.g., schizophrenia). miR-29 family is a miRNA family contributing to brain maturation. miR-29 knockout in animal studies is reported to correlate with psychiatric disorders very similar to those seen in schizophrenia. In this study, we aimed to evaluate the miR-29a level in patients with schizophrenia and its potential value in the diagnosis of schizophrenia.

MATERIALS AND METHODS

The serum sample of 42 patients with schizophrenia and 40 healthy subjects were obtained from the Azeri Recent onset/Acute phase psychosis Survey (ARAS) Cohort study. After preparations, the expression level of miR-29a was investigated by real-time PCR. The SPSS and GraphPad prism software were used to analyze the relation between miR-29a level and clinical parameters and its potential as a biomarker for the diagnosis of schizophrenia.

RESULTS

Our study showed a significantly lower miR-29a level in patients compared to healthy controls (p = 0.0012). Furthermore, miR-29a level was significantly lower in some types of schizophrenia (p = 0.024). miR-29a level was not related to sex, age, or heredity (p > 0.05). miR-29a also showed 80% specificity and 71.43% sensitivity in the diagnosis of schizophrenia.

CONCLUSION

Downregulation of miR-29a in schizophrenia is significantly related to the development of this illness. It might have the potential as a biomarker for schizophrenia.

Establishment of the Myeloid TBX-Code Reveals Aberrant Expression of T-Box Gene TBX1 in Chronic Myeloid Leukemia

T-box genes encode transcription factors, which control developmental processes and promote cancer if deregulated. Recently, we described the lymphoid TBX-code, which collates T-box gene activities in normal lymphopoiesis, enabling identification of members deregulated in lymphoid malignancies. Here, we have extended this analysis to cover myelopoiesis, compiling the myeloid TBX-code and, thus, highlighting which of these genes might be deregulated in myeloid tumor types. We analyzed public T-box gene expression datasets bioinformatically for normal and malignant cells. Candidate T-box-gene-expressing model cell lines were identified and examined by RQ-PCR, Western Blotting, genomic profiling, and siRNA-mediated knockdown combined with RNA-seq analysis and live-cell imaging. The established myeloid TBX-code comprised 10 T-box genes, including progenitor-cell-restricted TBX1. Accordingly, we detected aberrant expression of TBX1 in 10% of stem/progenitor-cell-derived chronic myeloid leukemia (CML) patients. The classic CML cell line K-562 expressed TBX1 at high levels and served as a model to identify TBX1 activators, including transcription factor GATA1 and genomic amplification of the TBX1 locus at 22q11; inhibitors, including BCR::ABL1 fusion and downregulated GNAI2, as well as BMP, FGF2, and WNT signaling; and the target genes CDKN1A, MIR17HG, NAV1, and TMEM38A. The establishment of the myeloid TBX-code permitted identification of aberrant TBX1 expression in subsets of CML patients and cell lines. TBX1 forms an integral part of an oncogenic regulatory network impacting proliferation, survival, and differentiation. Thus, the data spotlight novel diagnostic markers and potential therapeutic targets for this malignancy.

Neuron navigators: A novel frontier with physiological and pathological implications

Neuron navigators are microtubule plus-end tracking proteins containing basic and serine rich regions which are encoded by neuron navigator genes (NAVs). Neuron navigator proteins are essential for neurite outgrowth, neuronal migration, and overall neurodevelopment along with some other functions as well. The navigator proteins are substantially expressed in the developing brain and have been reported to be differentially expressed in various tissues at different ages. Over the years, the research has found neuron navigators to be implicated in a spectrum of pathological conditions such as developmental anomalies, neurodegenerative disorders, neuropathic pain, anxiety, cancers, and certain inflammatory conditions. The existing knowledge about neuron navigators remains sparse owing to their differential functions, undiscovered modulators, and unknown molecular mechanisms. Investigating the possible role of neuron navigators in various physiological processes and pathological conditions pose as a novel field that requires extensive research and might provide novel mechanistic insights and understanding of these aspects.

Apnea of prematurity induces short and long-term development-related transcriptional changes in the murine cerebellum

Apnea of prematurity (AOP) affects more than 50% of preterm infants and leads to perinatal intermittent hypoxia (IH) which is a major cause of morbimortality worldwide. At birth, the human cerebellar cortex is still immature, making it vulnerable to perinatal events. Additionally, studies have shown a correlation between cerebellar functions and the deficits observed in children who have experienced AOP. Yet, the cerebellar alterations underpinning this link remain poorly understood. To gain insight into the involvement of the cerebellum in perinatal hypoxia-related consequences, we developed a mouse model of AOP. Our previous research has revealed that IH induces oxidative stress in the developing cerebellum, as evidenced by the over-expression of genes involved in reactive oxygen species production and the under-expression of genes encoding antioxidant enzymes. These changes suggest a failure of the defense system against oxidative stress and could be responsible for neuronal death in the cerebellum. Building upon these findings, we conducted a transcriptomic study of the genes involved in the processes that occur during cerebellar development. Using real-time PCR, we analyzed the expression of these genes at different developmental stages and in various cell types. This enabled us to pinpoint a timeframe of vulnerability at P8, which represents the age with the highest number of downregulated genes in the cerebellum. Furthermore, we discovered that our IH protocol affects several molecular pathways, including proliferation, migration, and differentiation. This indicates that IH can impact the development of different cell types, potentially contributing to the histological and behavioral deficits observed in this model. Overall, our data strongly suggest that the cerebellum is highly sensitive to IH, and provide valuable insights into the cellular and molecular mechanisms underlying AOP. In the long term, these findings may contribute to the identification of novel therapeutic targets for improving the clinical management of this prevalent pathology.