Regulation of Human PAX6 Expression by miR-7

CircNetVis: an interactive web application for visualizing interaction networks of circular RNAs

Analyzing the interactions of circular RNAs (circRNAs) is a crucial step in understanding their functional impacts. While there are numerous visualization tools available for investigating circRNA interaction networks, these tools are typically limited to known circRNAs from specific databases. Moreover, these existing tools usually require complex installation procedures which can be time-consuming and challenging for users. There is a lack of a user-friendly web application that facilitates interactive exploration and visualization of circRNA interaction networks. CircNetVis is an interactive online web application to enhance the analysis of human/mouse circRNA interactions. The tool allows three different input formats of circRNAs including circRNA IDs from CircBase, circRNA coordinates (chromosome, start position, end position), and circRNA sequences in the FASTA format. It integrates multiple interaction networks for visualization and investigation of the interplay between circRNA, microRNAs, mRNAs and RNA binding proteins. CircNetVis also enables users to interactively explore the interactions of unknown circRNAs which are not reported from previous databases. The tool can generate interactive plots and allows users to save results as output files for offline usage. CircNetVis is implemented as a web application using R-shiny and freely available for academic use at https://www.meb.ki.se/shiny/truvu/CircNetVis/ .

Congenital aniridia beyond black eyes: From phenotype and novel genetic mechanisms to innovative therapeutic approaches

Congenital PAX6-aniridia, initially characterized by the absence of the iris, has progressively been shown to be associated with other developmental ocular abnormalities and systemic features making congenital aniridia a complex syndromic disorder rather than a simple isolated disease of the iris. Moreover, foveal hypoplasia is now recognized as a more frequent feature than complete iris hypoplasia and a major visual prognosis determinant, reversing the classical clinical picture of this disease. Conversely, iris malformation is also a feature of various anterior segment dysgenesis disorders caused by PAX6-related developmental genes, adding a level of genetic complexity for accurate molecular diagnosis of aniridia. Therefore, the clinical recognition and differential genetic diagnosis of PAX6-related aniridia has been revealed to be much more challenging than initially thought, and still remains under-investigated. Here, we update specific clinical features of aniridia, with emphasis on their genotype correlations, as well as provide new knowledge regarding the PAX6 gene and its mutational spectrum, and highlight the beneficial utility of clinically implementing targeted Next-Generation Sequencing combined with Whole-Genome Sequencing to increase the genetic diagnostic yield of aniridia. We also present new molecular mechanisms underlying aniridia and aniridia-like phenotypes. Finally, we discuss the appropriate medical and surgical management of aniridic eyes, as well as innovative therapeutic options. Altogether, these combined clinical-genetic approaches will help to accelerate time to diagnosis, provide better determination of the disease prognosis and management, and confirm eligibility for future clinical trials or genetic-specific therapies.

MicroRNA-7 regulates insulin signaling pathway by targeting IRS1, IRS2, and RAF1 genes in gestational diabetes mellitus

BACKGROUND

Small non-coding micro RNAs (miRNAs) are indicated in various metabolic processes and play a critical role in disease pathology, including gestational diabetes mellitus (GDM).

OBJECTIVE

The purpose of this study was to examine the altered expression of miRNAs and their target genes in placental tissue (PL), cord blood (CB), and maternal blood (MB) of matched non-glucose tolerant (NGT) and GDM mother.

METHODS

In a case-control study, micro-RNA was quantified from forty-five serum (MB n = 15, CB n = 15, and PL n = 15) and matched placental tissue using stem-loop RT-qPCR followed by target prediction, network construction and functional and pathways enrichment analysis. Further, target genes were verified in-vitro through transfection and RT-qPCR.

RESULTS

Five miRNAs, namely hsa-let 7a-5P, hsa-miR7-5P, hsa-miR9-5P, hsa-miR18a-5P, and hsa-miR23a-3P were significantly over-expressed (p < 0.05) in all three samples namely PL, CB, and MB of GDM patients. However, the sample-wise comparison reveals higher expression of miRNA 7 in MB while lowest in CB than control. Furthermore, a comparison of fold change expression of target genes discloses a lower expression of IRS1, IRS2, and RAF1 in MB while comparatively higher expression of NRAS in MB and CB. In-vitro validation reveals lower expression of IRS1/2 and RAF1 in response to overexpression of miR-7 and vice-versa. Thus it is evident that increased miRNA7 expression causes down-regulation of its target genes IRS1, IRS2, and RAF1 in GDM mother compared to control. Further, target prediction, pathway enrichment, and hormone analysis (significantly higher FSH & LH in MB of GDM compared to NGT) revealed the insulin signaling, inflammatory and GnRH signaling as major pathways regulated by miRNA7.

CONCLUSIONS

Thus, an elevated level of miRNA7 may be associated with the progression of GDM by altering the multiple pathways like insulin, GnRH, and inflammatory signaling pathways via targeting IRS1, IRS2, and RAF1, implicating a new therapeutic target for GDM.

Circular RNAs regulate cancer-related signaling pathways and serve as potential diagnostic biomarkers for human cancers

Circular RNAs (circRNAs) are RNAs that have an important role in various pathological processes, including cancer. After the usage of high-throughput RNA sequencing, many circRNAs were found to be differentially expressed in various cancer cell lines and regulate cell signaling pathways by modulating particular gene expressions. Understanding their role in these pathways and what cancers they are found in can set the stage for identifying diagnostic and prognostic biomarkers and therapeutic targets of cancer. This paper will discuss which circRNAs are found in different cancers and what mechanisms they use to upregulate or downregulate certain cellular components.

The Role of miRNA-7 in the Biology of Cancer and Modulation of Drug Resistance

MicroRNAs (miRNAs, miRs) are small non-coding RNA (ncRNA) molecules capable of regulating post-transcriptional gene expression. Imbalances in the miRNA network have been associated with the development of many pathological conditions and diseases, including cancer. Recently, miRNAs have also been linked to the phenomenon of multidrug resistance (MDR). MiR-7 is one of the extensively studied miRNAs and its role in cancer progression and MDR modulation has been highlighted. MiR-7 is engaged in multiple cellular pathways and acts as a tumor suppressor in the majority of human neoplasia. Its depletion limits the effectiveness of anti-cancer therapies, while its restoration sensitizes cells to the administered drugs. Therefore, miR-7 might be considered as a potential adjuvant agent, which can increase the efficiency of standard chemotherapeutics.

miRNAs and Müller Glia Reprogramming During Retina Regeneration

The use of model systems that are capable of robust, spontaneous retina regeneration has allowed for the identification of genetic pathways and components that are required for retina regeneration. Complemented by mouse models in which retina regeneration can be induced after forced expression of key factors, altered chromatin accessibility, or inhibition of kinase/signaling cascades, a clearer picture of the key regulatory events that control retina regeneration is emerging. In all cases, Müller glia (MG) serve as an adult retinal stem cell that must be reprogrammed to allow for regeneration, with the end goal being to understand why regenerative pathways are blocked in mammals, but spontaneous in other vertebrates such as zebrafish. miRNAs have emerged as key gene regulatory molecules that control both development and regeneration in vertebrates. Here, we focus on a small subset of miRNAs that control MG reprogramming during retina regeneration and have the potential to serve as therapeutic targets for treatment of visual disorders and damage.

Systematic Review and Bioinformatic Analysis of microRNA Expression in Autism Spectrum Disorder Identifies Pathways Associated With Cancer, Metabolism, Cell Signaling, and Cell Adhesion

Background: Previous studies have identified differentially expressed microRNAs in autism spectrum disorder (ASD), however, results are discrepant. We aimed to systematically review this topic and perform bioinformatic analysis to identify genes and pathways associated with ASD miRNAs. Methods: Following the Preferred Reporting Items for Systematic reviews and Meta-Analyses, we searched the Web of Science, PubMed, Embase, Scopus, and OVID databases to identify all studies comparing microRNA expressions between ASD persons and non-ASD controls on May 11, 2020. We obtained ASD miRNA targets validated by experimental assays from miRTarBase and performed pathway enrichment analysis using Metascape and DIANA-miRPath v3. 0. Results: Thirty-four studies were included in the systematic review. Among 285 altered miRNAs reported in these studies, 15 were consistently upregulated, 14 were consistently downregulated, and 39 were inconsistently dysregulated. The most frequently altered miRNAs including miR-23a-3p, miR-106b-5p, miR-146a-5p, miR-7-5p, miR-27a-3p, miR-181b-5p, miR-486-3p, and miR-451a. Subgroup analysis of tissues showed that miR-146a-5p, miR-155-5p, miR-1277-3p, miR-21-3p, miR-106b-5p, and miR-451a were consistently upregulated in brain tissues, while miR-4742-3p was consistently downregulated; miR-23b-3p, miR-483-5p, and miR-23a-3p were consistently upregulated in blood samples, while miR-15a-5p, miR-193a-5p, miR-20a-5p, miR-574-3p, miR-92a-3p, miR-3135a, and miR-103a-3p were consistently downregulated; miR-7-5p was consistently upregulated in saliva, miR-23a-3p and miR-32-5p were consistently downregulated. The altered ASD miRNAs identified in at least two independent studies were validated to target many autism risk genes. TNRC6B, PTEN, AGO1, SKI, and SMAD4 were the most frequent targets, and miR-92a-3p had the most target autism risk genes. Pathway enrichment analysis showed that ASD miRNAs are significantly involved in pathways associated with cancer, metabolism (notably Steroid biosynthesis, Fatty acid metabolism, Fatty acid biosynthesis, Lysine degradation, Biotin metabolism), cell cycle, cell signaling (especially Hippo, FoxO, TGF-beta, p53, Thyroid hormone, and Estrogen signaling pathway), adherens junction, extracellular matrix-receptor interaction, and Prion diseases. Conclusions: Altered miRNAs in ASD target autism risk genes and are involved in various ASD-related pathways, some of which are understudied and require further investigation.

MicroRNA-7: expression and function in brain physiological and pathological processes

MicroRNAs (miRNAs) are a class of small non-coding RNAs that regulate gene expression at the post-transcriptional level and play critical roles in regulating physiological function, and are becoming worldwide research hot spot in brain development and diseases. However, the exact value of miRNAs in brain physiological and pathological processes remain to be fully elucidated, which is vital for the application of miRNAs as diagnostic, prognostic, and therapeutic biomarkers for brain diseases. MicroRNA-7 (miR-7), as a highly expressed miRNA molecule in the mammalian brain, is well documented to play a critical role in development of various diseases. Importantly, accumulating evidence has shown that miR-7 is involved in a range of developmental and pathological processes of brain. Expressively, miR-7, encoded by three genes located different chromosomes, is dominantly expressed in neurons with sensory or neurosecretory. Moreover, the expression of miR-7 is regulated at three levels including gene transcription, process of primary and precursor sequence and formation of mature sequence. Physiologically, miR-7 principally governs the physiological development of Pituitary gland, Optic nervous system and Cerebral cortex. Pathologically, miR-7 can regulate multiple genes thereby manipulating the process of various brain diseases including neurodegenerative diseases, neuroinflammation, and mental disorders and so on. These emerging studies have shown that miR-7, a representative member of miRNA family, might be a novel intrinsic regulatory molecule involved in the physiological and pathological process of brain. Therefore, in-depth studies on the role of miR-7 in brain physiology and pathology undoubtedly not only provide a light on the roles of miRNAs in brain development and diseases, but also are much helpful for ultimate development of therapeutic strategies against brain diseases. In this review, we provide an overview of current scientific knowledge regarding the expression and function of miR-7 in development and disease of brain and raise many issues involved in the relationship between miR-7 and brain physiological and pathological processes.

Abnormal neovascular and proliferative conjunctival phenotype in limbal stem cell deficiency is associated with altered microRNA and gene expression modulated by PAX6 mutational status in congenital aniridia

PURPOSE

To evaluate conjunctival cell microRNA (miRNAs) and mRNA expression in relation to observed phenotype of progressive limbal stem cell deficiency in a cohort of subjects with congenital aniridia with known genetic status.

METHODS

Using impression cytology, bulbar conjunctival cells were sampled from 20 subjects with congenital aniridia and 20 age and sex-matched healthy control subjects. RNA was extracted and miRNA and mRNA analyses were performed using microarrays. Results were related to severity of keratopathy and genetic cause of aniridia.

RESULTS

Of 2549 miRNAs, 21 were differentially expressed in aniridia relative to controls (fold change ≤ -1.5 or ≥ +1.5). Among these miR-204-5p, an inhibitor of corneal neovascularization, was downregulated 26.8-fold in severely vascularized corneas. At the mRNA level, 539 transcripts were differentially expressed (fold change ≤ -2 or ≥ +2), among these FOSB and FOS were upregulated 17.5 and 9.7-fold respectively, and JUN by 2.9-fold, all being components of the AP-1 transcription factor complex. Pathway analysis revealed enrichment of PI3K-Akt, MAPK, and Ras signaling pathways in aniridia. For several miRNAs and transcripts regulating retinoic acid metabolism, expression levels correlated with keratopathy severity and genetic status.

CONCLUSION

Strong dysregulation of key factors at the miRNA and mRNA level suggests that the conjunctiva in aniridia is abnormally maintained in a pro-angiogenic and proliferative state, and these changes are expressed in a PAX6 mutation-dependent manner. Additionally, retinoic acid metabolism is disrupted in severe, but not mild forms of the limbal stem cell deficiency in aniridia.

MicroRNA-758 acts as a tumor inhibitor in colorectal cancer through targeting PAX6 and regulating PI3K/AKT pathway

Recently, a number of microRNAs (miRNAs) have been reported to play different roles in human cancers, including colorectal cancer (CRC). However, the specific role of miR-758 has not been clarified in CRC. Therefore, the aim of the present study was to explore the role of miR-758 in CRC. RT-qPCR and western blot analysis were used to quantify the expression of miR-758 and genes. The function of miR-758 in CRC was investigated using Transwell, CCK-8 and luciferase reporter assays. According to the results, the downregulation of miR-758 expression was associated with aggressive behavior and poor prognosis in CRC patients. miR-758 was shown to restrain the cell viability and metastasis in CRC. In addition, it was confirmed that miR-758 directly targets PAX6 and inhibits CRC progression through targeting PAX6. The results also revealed that miR-758 blocked EMT and PI3K/AKT pathway in CRC. In conclusion, miR-758 acts as a tumor suppressor in CRC by downregulating PAX6.

Circular RNAs: Potential Regulators of Treatment Resistance in Human Cancers

Circular RNAs (circRNAs) which were once considered as "junk" are now in the spotlight as a potential player in regulating human diseases, especially cancer. With the development of high throughput technologies in recent years, the full potential of circRNAs is being uncovered. CircRNAs possess some unique characteristics and advantageous properties that could benefit medical research and clinical applications. CircRNAs are stable with covalently closed loops that are resistant to ribonucleases, have disease stage-specific expressions and are selectively abundant in different types of tissues. Interestingly, the presence of circRNAs in different types of treatment resistance in human cancers was recently observed with the involvement of a few key pathways. The activation of certain pathways by circRNAs may give new insights to treatment resistance management. The potential usage of circRNAs from this aspect is very much in its infancy stage and has not been fully validated. This mini-review attempts to highlight the possible role of circRNAs as regulators of treatment resistance in human cancers based on its intersection molecules and cancer-related regulatory networks.

Mapping the Pax6 3' untranslated region microRNA regulatory landscape

BACKGROUND

PAX6 is a homeodomain transcription factor that acts in a highly dosage-sensitive manner to regulate the development and function of the eyes, nose, central nervous system, gut, and endocrine pancreas. Several individual microRNAs (miRNA) have been implicated in regulating PAX6 in different cellular contexts, but a more general view of how they contribute to the fine-tuning and homeostasis of PAX6 is poorly understood.

RESULTS

Here, a comprehensive analysis of the Pax6 3' untranslated region was performed to map potential miRNA recognition elements and served as a backdrop for miRNA expression profiling experiments to identify potential cell/tissue-specific miRNA codes. Pax6 3'UTR pull-down studies identified a cohort of miRNA interactors in pancreatic αTC1-6 cells that, based on the spacing of their recognition sites in the Pax6 3'UTR, revealed 3 clusters where cooperative miRNA regulation may occur. Some of these interacting miRNAs have been implicated in α cell function but have not previously been linked to Pax6 function and may therefore represent novel PAX6 regulators.

CONCLUSIONS

These findings reveal a regulatory landscape upon which miRNAs may participate in the developmental control, fine-tuning and/or homeostasis of PAX6 levels.

A stress-induced response complex (SIRC) shuttles miRNAs, siRNAs, and oligonucleotides to the nucleus

The deregulation of miRNA function is critical in the pathogenesis of cancer and other diseases. miRNAs and other noncoding RNAs (ncRNAs) tightly regulate gene expression, often in the cell nucleus. Heretofore, there has been no understanding that there exists a general shuttling mechanism that brings miRNAs, in addition to therapeutic oligonucleotides and siRNAs, from the cytoplasm into the nucleus. We have identified this shuttling mechanism, which occurs in response to cell stress. Nuclear imported miRNAs are functional, can potentially alter gene expression, and participate in cell stress response mechanisms. This shuttling mechanism can be augmented to target specific RNAs, including miRNA sponges, and long ncRNAs like Malat-1, which have been implicated in promoting tumor metastasis.

Although some information is available for specific subsets of miRNAs and several factors have been shown to bind oligonucleotides (ONs), no general transport mechanism for these molecules has been identified to date. In this work, we demonstrate that the nuclear transport of ONs, siRNAs, and miRNAs responds to cellular stress. Furthermore, we have identified a stress-induced response complex (SIRC), which includes Ago-1 and Ago-2 in addition to the transcription and splicing regulators YB1, CTCF, FUS, Smad1, Smad3, and Smad4. The SIRC transports endogenous miRNAs, siRNAs, and ONs to the nucleus. We show that cellular stress can significantly increase ON- or siRNA-directed splicing switch events and endogenous miRNA targeting of nuclear RNAs.

Analysis of the complex interaction of CDR1as-miRNA-protein and detection of its novel role in melanoma

Despite improvements in the prevention, diagnosis and treatment of melanoma having developed rapidly, the role of circular RNA CDR1 antisense RNA (CDR1as) in melanoma remains to be elucidated. The aim of the present study was to predict the novel roles of CDR1as in melanoma through novel bioinformatics analysis. In the present study, the circ2Traits database was used to supply information on CDR1as in cancer. CircNet, circBase and circInteractome databases were used to detect the co-expression of CDR1as, microRNAs and proteins. Furthermore, the functions and pathways of the associated proteins were predicted using the Database for Annotation, Visualization and Integrated Discovery. Gene Ontology enrichment analysis suggested that the proteins associated with CDR1as were mainly regulated in the cytoplasm as the molecular protein binding, the biological process of cell division and the endoplasmic reticulum tubular network, which are all involved in cancer-related processes. The Kyoto Encyclopedia of Genes and Genome pathway cell cycle was closely associated with the location of cancer. Co-expression network analysis revealed the associations among CDR1as, microRNAs and proteins. The bioinformatics analysis showed that CDR1as may act as the competing endogenous RNA for the vital genes, which are associated with the invasion and migration of melanoma.

MicroRNA-365 modulates astrocyte conversion into neuron in adult rat brain after stroke by targeting Pax6

Reactive astrocytes induced by ischemia can transdifferentiate into mature neurons. This neurogenic potential of astrocytes may have therapeutic value for brain injury. Epigenetic modifications are widely known to involve in developmental and adult neurogenesis. PAX6, a neurogenic fate determinant, contributes to the astrocyte‐to‐neuron conversion. However, it is unclear whether microRNAs (miRs) modulate PAX6‐mediated astrocyte‐to‐neuron conversion. In the present study we used bioinformatic approaches to predict miRs potentially targeting Pax6, and transient middle cerebral artery occlusion (MCAO) to model cerebral ischemic injury in adult rats. These rats were given striatal injection of glial fibrillary acidic protein targeted enhanced green fluorescence protein lentiviral vectors (Lv‐GFAP‐EGFP) to permit cell fate mapping for tracing astrocytes‐derived neurons. We verified that miR‐365 directly targets to the 3′‐UTR of Pax6 by luciferase assay. We found that miR‐365 expression was significantly increased in the ischemic brain. Intraventricular injection of miR‐365 antagomir effectively increased astrocytic PAX6 expression and the number of new mature neurons derived from astrocytes in the ischemic striatum, and reduced neurological deficits as well as cerebral infarct volume. Conversely, miR‐365 agomir reduced PAX6 expression and neurogenesis, and worsened brain injury. Moreover, exogenous overexpression of PAX6 enhanced the astrocyte‐to‐neuron conversion and abolished the effects of miR‐365. Our results demonstrate that increase of miR‐365 in the ischemic brain inhibits astrocyte‐to‐neuron conversion by targeting Pax6, whereas knockdown of miR‐365 enhances PAX6‐mediated neurogenesis from astrocytes and attenuates neuronal injury in the brain after ischemic stroke. Our findings provide a foundation for developing novel therapeutic strategies for brain injury.

PAX6: 25th anniversary and more to learn

The DNA-binding transcription factor PAX6 was cloned 25 years ago by multiple teams pursuing identification of human and mouse eye disease causing genes, cloning vertebrate homologues of pattern-forming regulatory genes identified in Drosophila, or abundant eye-specific transcripts. Since its discovery in 1991, genetic, cellular, molecular and evolutionary studies on Pax6 mushroomed in the mid 1990s leading to the transformative thinking regarding the genetic program orchestrating both early and late stages of eye morphogenesis as well as the origin and evolution of diverse visual systems. Since Pax6 is also expressed outside of the eye, namely in the central nervous system and pancreas, a number of important insights into the development and function of these organs have been amassed. In most recent years, genome-wide technologies utilizing massively parallel DNA sequencing have begun to provide unbiased insights into the regulatory hierarchies of specification, determination and differentiation of ocular cells and neurogenesis in general. This review is focused on major advancements in studies on mammalian eye development driven by studies of Pax6 genes in model organisms and future challenges to harness the technology-driven opportunities to reconstruct, step-by-step, the transition from naïve ectoderm, neuroepithelium and periocular mesenchyme/neural crest cells into the three-dimensional architecture of the eye.

MicroRNA-7: A miRNA with expanding roles in development and disease

MicroRNAs (miRNAs) are a family of short, non-coding RNA molecules (∼22nt) involved in post-transcriptional control of gene expression. They act via base-pairing with mRNA transcripts that harbour target sequences, resulting in accelerated mRNA decay and/or translational attenuation. Given miRNAs mediate the expression of molecules involved in many aspects of normal cell development and functioning, it is not surprising that aberrant miRNA expression is closely associated with many human diseases. Their pivotal role in driving a range of normal cellular physiology as well as pathological processes has established miRNAs as potential therapeutics, as well as potential diagnostic and prognostic tools in human health. MicroRNA-7 (miR-7) is a highly conserved miRNA which displays restricted spatiotemporal expression during development and in maturity. In humans and mice, mature miR-7 is generated from three different genes, illustrating unexpected redundancy and also the importance of this miRNA in regulating key cellular processes. In this review we examine the expanding role of miR-7 in the context of health, with emphasis on organ differentiation and development, as well as in various mammalian diseases, particularly of the brain, heart, endocrine pancreas and skin, as well as in cancer. The more we learn about miR-7, the more we realise the complexity of its regulation and potential functional application both from a biomarker and therapeutic perspective.

MicroRNA-7: a promising new target in cancer therapy

The incidence of tumors with life-threatening effects has increased gradually over time; however, the mechanisms involved in tumor development have not been fully elucidated. Recent studies have shown that microRNA-7 (miR-7), which is endogenous non-coding RNA molecules of approximately 23 nucleotides, plays an important role in the occurrence and development of tumors as a key tumor suppressor. Mechanistic evidence showed that miR-7 is closely related to the growth, metastasis, and prognosis of various malignant tumors through regulating different target molecules, which suggest that miR-7 may be a new target for the clinical diagnosis and treatment of various tumors. In this review, we summarize current knowledge of the relationship between miR-7 and tumor development, diagnosis, and treatment.

Sustained Pax6 Expression Generates Primate-like Basal Radial Glia in Developing Mouse Neocortex

The evolutionary expansion of the neocortex in mammals has been linked to enlargement of the subventricular zone (SVZ) and increased proliferative capacity of basal progenitors (BPs), notably basal radial glia (bRG). The transcription factor Pax6 is known to be highly expressed in primate, but not mouse, BPs. Here, we demonstrate that sustaining Pax6 expression selectively in BP-genic apical radial glia (aRG) and their BP progeny of embryonic mouse neocortex suffices to induce primate-like progenitor behaviour. Specifically, we conditionally expressed Pax6 by in utero electroporation using a novel, Tis21–CreER^T2 mouse line. This expression altered aRG cleavage plane orientation to promote bRG generation, increased cell-cycle re-entry of BPs, and ultimately increased upper-layer neuron production. Upper-layer neuron production was also increased in double-transgenic mouse embryos with sustained Pax6 expression in the neurogenic lineage. Strikingly, increased BPs existed not only in the SVZ but also in the intermediate zone of the neocortex of these double-transgenic mouse embryos. In mutant mouse embryos lacking functional Pax6, the proportion of bRG among BPs was reduced. Our data identify specific Pax6 effects in BPs and imply that sustaining this Pax6 function in BPs could be a key aspect of SVZ enlargement and, consequently, the evolutionary expansion of the neocortex.

"Humanizing" the expression of the transcription factor Pax6 in cortical progenitors in the developing mouse brain is sufficient to endow these progenitors with a primate-like proliferative capacity.

During development, neural progenitors generate all cells that make up the mammalian brain. Differences in brain size among the various mammalian species are attributed to differences in the abundance and proliferative capacity of a specific class of neural progenitors called basal progenitors. Among these, a specific progenitor type called basal radial glia is thought to have played an important role during evolution in the expansion of the neocortex, the part of the brain associated with higher cognitive functions like conscious thought and language. In the neocortex, the expression of the transcription factor Pax6 in basal progenitors is low in rodents, but high in primates, including humans. In this study, we aimed to mimic the elevated expression pattern of Pax6 seen in humans in basal progenitors of the embryonic mouse neocortex. To this end, we generated a novel, transgenic mouse line that allows sustained expression of the Pax6 gene in basal progenitors. This elevated expression resulted in an increase in the generation of basal radial glia, in the proliferative capacity of basal progenitors, and, ultimately, in the number of neurons produced. Our findings demonstrate that altering the expression of a single transcription factor from a mouse to a human-like pattern suffices to induce a primate-like proliferative behaviour in neural progenitors, which is thought to underlie the evolutionary expansion of the neocortex.

Circulating microRNAs in Diabetes Progression: Discovery, Validation, and Research Translation

Diabetes, in all of its forms, is a disease state that demonstrates wide ranging pathological effects throughout the body. Until now, the only method of diagnosing and monitoring the progression of diabetes was through the measurement of blood glucose. Unfortunately, beta cell dysfunction initiates well before the clinical onset of diabetes, and so the development of an effective biomarker signature is of paramount importance to predict and monitor the progression of this disease. MicroRNAs (miRNAs/miRs) are small (18-22 nucleotide) noncoding (nc)RNAs that post-transcriptionally regulate endogenous gene expression by targeted inhibition or degradation of messenger (m)RNA. Recently, miRNAs have shown great promise as biomarkers as some exhibit differential expression in multiple disease states, including type 1 and type 2 diabetes (T1D/T2D). Furthermore, miRNAs are quite stable in circulation, resistant to freeze-thaw and pH-mediated degradation, and are relatively easy to detect using quantitative (q)PCR. Here, we discuss microRNAs that may form a diabetes biomarker signature. To identify these transcripts we outline miRNAs that play a central role in pancreas development and diabetes, as well as previously identified miRNAs with differential expression in individuals with T1D and T2D. Validation and refinement of a miRNA biomarker signature for diabetes would allow identification and intervention of individuals at risk of this disease, as well as stratification and monitoring of patients with established diabetes.