Dissection of the role of Pinin in the development of zebrafish posterior pharyngeal cartilages

Quantitative proteomics reveals the dynamic proteome landscape of zebrafish embryos during the maternal-to-zygotic transition

Maternal-to-zygotic transition (MZT) is central to early embryogenesis. However, its underlying molecular mechanisms are still not well described. Here, we revealed the expression dynamics of 5,000 proteins across four stages of zebrafish embryos during MZT, representing one of the most systematic surveys of proteome landscape of the zebrafish embryos during MZT. Nearly 700 proteins were differentially expressed and were divided into six clusters according to their expression patterns. The proteome expression profiles accurately reflect the main events that happen during the MZT, i.e., zygotic genome activation (ZGA), clearance of maternal mRNAs, and initiation of cellular differentiation and organogenesis. MZT is modulated by many proteins at multiple levels in a collaborative fashion, i.e., transcription factors, histones, histone-modifying enzymes, RNA helicases, and P-body proteins. Significant discrepancies were discovered between zebrafish proteome and transcriptome profiles during the MZT. The proteome dynamics database will be a valuable resource for bettering our understanding of MZT.

Neuronal Pnn Deficiency Increases Oxidative Stress and Exacerbates Cerebral Ischemia/Reperfusion Injury in Mice

Cerebral stroke remains one of the leading causes of death worldwide. Ischemic stroke caused by the sudden loss of blood flow in brain is the major type of cerebral stroke. In addition to necrotic cell death in the ischemic core region, neuronal apoptosis is usually observed in the ischemic penumbra. Pnn, a multi-functional protein, participates in cellular proliferation, migration, differentiation, apoptosis as well as cell–cell interaction through its abilities in regulating gene transcription and mRNA processing. Our recent studies have demonstrated that Pnn has a cell type-specific distribution manner in neural cells under ischemic injury and plays a protective role in astrocytes against ischemic stress. In this study, we generated an inducible neuron-specific Pnn deficiency mouse model to further investigate the physiological role of Pnn in neurons. To directly examine the role of neuronal Pnn in ischemic stress, four weeks after induction of Pnn deficiency in neurons, middle cerebral artery occlusion (MCAO) was applied to induce cerebral ischemia/reperfusion in mice. In the cerebrum and hippocampus with neuronal Pnn depletion, the expression of SRSF2, a mRNA splicing regulator, was increased, while the expression of SRSF1, a functional antagonist of SRSF2, was reduced. Expression levels of ROS generators (NOX-1 and NOX-2) and antioxidant proteins (GR, HO-1, NQO-1) were upregulated in brain tissue with loss of neuronal Pnn, echoing an increase in oxidized proteins in cortical and hippocampal neurons. Furthermore, the expression of DNA damage marker, p53bp1, was found in the choroid plexus of mice with neuronal Pnn depletion. In mice with MCAO, compared to wild type mice, both increased cerebral infarcted area and elevated expressions of proapoptotic proteins were found in mice with neuronal Pnn depletion. In conclusion, Pnn deficiency increases oxidative stress in neurons and exacerbates cerebral ischemia/reperfusion injury in mice.

Pinin Induces Epithelial-to-Mesenchymal Transition in Hepatocellular Carcinoma by Regulating m6A Modification

Pinin is a moonlighting protein localized in desmosomes and nucleus. It could promote the growth of hepatocellular carcinoma. Whether this protein can induce epithelial-to-mesenchymal transition (EMT) and malignant progression in HCC is unknown. This work found that Pinin prompts EMT in vitro and in vivo. Further mechanism study found that Pinin increases the level of N6-methyladenosine (m6A) modification of RNA by interacting with METTL3, which in turn induces snail1 expression. These findings suggest that Pinin induces EMT by regulating m6A modification and, thus, could be a potential anticancer target for HCC therapy.

The role and regulation of Pnn in proliferative and non-dividing cells: Form embryogenesis to pathogenesis

Pnn, a multiple functional protein, plays roles in embryonic development, cellular differentiation, tumorigenesis, and metastasis. In the past two decades, the functions of Pnn in regulating RNA alternative splicing, gene regulation, and cell-cell connection have been revealed. Although Pnn is originally identified as a desmosome-associated protein for linking desmosome and intermediated filament, emerging evidence implies that Pnn not only is a desmosome protein but also plays critical roles in the nucleus. To date, through cell biology investigation and the generation of animal models with genetic manipulation, the physiological role of Pnn has been characterized in the research fields of developmental biology, tumor biology, and neuroscience. Through proteomic and molecular biology studies, transcription regulators, splicing regulators, and cytoskeletal proteins were found to interact with Pnn. In addition, histopathological and biochemical evidence has pointed to an association of Pnn expression level with tumorigenesis and metastasis. A previous clinical study also demonstrated a correlation between a reduced expression of Pnn and human dementia. Besides, experimental studies showed a protective role of Pnn against ischemic stress in astrocytes. All indicated a variety of roles of Pnn in different cell types. In this review article, we introduced the role of Pnn in embryogenesis and pathogenesis as well as discussed its potential clinical application.

Expression and Distribution Pattern of Pnn in Ischemic Cerebral Cortex and Cultured Neural Cells Exposed to Oxygen-Glucose Deprivation

Pinin (Pnn), a multifunctional protein, participates in embryonic development as well as in cellular apoptosis, proliferation, and migration through regulating mRNA alternative splicing and gene transcription. Previous studies have shown that Pnn plays important roles in neural system development and the expression level of Pnn in astrocytes is altered by ischemic stress and associated with cellular apoptosis. In the present study, we further utilized primary cultured rat neurons and astrocytes with oxygen-glucose deprivation (OGD) and a mouse model with middle cerebral artery occlusion (MCAO)-induced ischemic stroke to examine the effect of ischemic stress on Pnn expression and distribution in different types of neural cells. Under normoxia, Pnn is mainly localized in the nuclear speckle of primary cultured neurons. The expression level of Pnn was increased after the OGD treatment and then decreased in the reoxygenation period. Moreover, the cytoplasmic expression of Pnn was observed in neurons with OGD and reoxygenation (OGD/R). Unlike that in neurons, the Pnn expression in astrocytes was decreased after OGD treatment and then gradually increased during the reoxygenation period. Of interest, the nuclear–cytoplasmic translocation of Pnn was not observed in astrocytes with OGD/R. In the MCAO mouse model, the neuronal expression of Pnn in the peri-ischemic region was reduced by three days post induction of ischemic stroke. However, the Pnn expression in astrocytes was not altered. Moreover, the nuclear speckle distribution of Pnn in neurons was also diminished following ischemic stroke. In conclusion, the Pnn expression and distribution after OGD and during reoxygenation showed distinct manners in neurons and astrocytes, implying that Pnn may play different roles in different types of neural cells in the stress response to ischemic injury.

A zebrafish model of Poikiloderma with Neutropenia recapitulates the human syndrome hallmarks and traces back neutropenia to the myeloid progenitor

Poikiloderma with Neutropenia (PN) is an autosomal recessive genodermatosis characterized by early-onset poikiloderma, pachyonychia, hyperkeratosis, bone anomalies and neutropenia, predisposing to myelodysplasia. The causative C16orf57/USB1 gene encodes a conserved phosphodiesterase that regulates the stability of spliceosomal U6-RNA. The involvement of USB1 in splicing has not yet allowed to unveil the pathogenesis of PN and how the gene defects impact on skin and bone tissues besides than on the haematological compartment. We established a zebrafish model of PN using a morpholino-knockdown approach with two different splicing morpholinos. Both usb1-depleted embryos displayed developmental abnormalities recapitulating the signs of the human syndrome. Besides the pigmentation and osteochondral defects, usb1-knockdown caused defects in circulation, manifested by a reduced number of circulating cells. The overall morphant phenotype was also obtained by co-injecting sub-phenotypic dosages of the two morpholinos and could be rescued by human USB1 RNA. Integrated in situ and real-time expression analyses of stage-specific markers highlighted defects of primitive haematopoiesis and traced back the dramatic reduction in neutrophil myeloperoxidase to the myeloid progenitors showing down-regulated pu.1 expression. Our vertebrate model of PN demonstrates the intrinsic requirement of usb1 in haematopoiesis and highlights PN as a disorder of myeloid progenitors associated with bone marrow dysfunction.

The Histochemistry and Cell Biology compendium: a review of 2012

The year 2012 was another exciting year for Histochemistry and Cell Biology. Innovations in immunohistochemical techniques and microscopy-based imaging have provided the means for advances in the field of cell biology. Over 130 manuscripts were published in the journal during 2012, representing methodological advancements, pathobiology of disease, and cell and tissue biology. This annual review of the manuscripts published in the previous year in Histochemistry and Cell Biology serves as an abbreviated reference for the readership to quickly peruse and discern trends in the field over the past year. The review has been broadly divided into multiple sections encompassing topics such as method advancements, subcellular components, extracellular matrix, and organ systems. We hope that the creation of this subdivision will serve to guide the reader to a specific topic of interest, while simultaneously providing a concise and easily accessible encapsulation of other topics in the broad area of Histochemistry and Cell Biology.