Studying Nestin and its Interrelationship with Cdk5

The optimal electrical stimulation for neural differentiation of conjunctiva mesenchymal stem cells

AIMS

The combination of biomaterial conductive scaffolds and electrical stimulation (ES) dramatically promotes stem cell differentiation into electro-responsive cells like neural cells. In this study, we aimed to fabricate PCL/PPY nanofiber scaffolds through the electrospinning method and investigate the effect of ES duration on neural differentiation of Conjunctiva Mesenchymal Stem Cells (CJMSCs).

METHODS

The topography of the fabricated scaffold was characterized using SEM and TEM microscopy, and its mechanical and other properties were determined by tensile, TGA, FTIR, and Contact angle tests. CJMSCs were seeded on the scaffolds and then subjected to electrical current (115 V m^-1 at 100 Hz) with durations of 1, 3, and 7 min for 3 days. Then the effect of nanofiber scaffold and electrical currents on cell viability and expression of neural marker genes (Nestin, β-tubulin, MAP-2) was investigated by MTT assay and qPCR analysis.

RESULTS

Our results revealed the good biocompatibility of the PCL-PPy nanofiber scaffold, and according to q-PCR results, the electrical stimulation of 1 min day^-1 for 3 days can induce neural differentiation of CJMSCs as indicated by the fold change of gene expression of Nestin (~127), B-tubulin (~30), and MAP-2 (~52).

CONCLUSION

This study emphasizes that the utilization of an electrically conductive nanofibrous scaffold in conjunction with electrical current has potential applications in the field of neural tissue engineering.

The Role of CDK5 in Tumours and Tumour Microenvironments

Cyclin-dependent kinase 5 (CDK5), which belongs to the protein kinase family, regulates neuronal function but is also associated with cancer development and has been proposed as a target for cancer treatment. Indeed, CDK5 has roles in cell proliferation, apoptosis, angiogenesis, inflammation, and immune response. Aberrant CDK5 activation triggers tumour progression in numerous types of cancer. In this review, we summarise the role of CDK5 in cancer and neurons and CDK5 inhibitors. We expect that our review helps researchers to develop CDK5 inhibitors as treatments for refractory cancer.

Intermediate filaments in developing neurons: Beyond structure

Neuronal development relies on a highly choreographed progression of dynamic cellular processes by which newborn neurons migrate, extend axons and dendrites, innervate their targets, and make functional synapses. Many of these dynamic processes require coordinated changes in morphology, powered by the cell's cytoskeleton. Intermediate filaments (IFs) are the third major cytoskeletal elements in vertebrate cells, but are rarely considered when it comes to understanding axon and dendrite growth, pathfinding and synapse formation. In this review, we first introduce the many new and exciting concepts of IF function, discovered mostly in non-neuronal cells. These roles include dynamic rearrangements, crosstalk with microtubules and actin filaments, mechano-sensing and -transduction, and regulation of signaling cascades. We then discuss the understudied roles of neuronally expressed IFs, with a particular focus on IFs expressed during development, such as nestin, vimentin and α-internexin. Lastly, we illustrate how signaling modulation by the unconventional IF nestin shapes neuronal morphogenesis in unexpected and novel ways. Even though the first IF knockout mice were made over 20 years ago, the study of the cell biological functions of IFs in the brain still has much room for exciting new discoveries.

Yokukansan, a Kampo medicine, enhances the level of neuronal lineage markers in differentiated P19 embryonic carcinoma cells

Yokukansan (YKS), a traditional Japanese Kampo medicine, affects neurological and psychiatric disorders. It ameliorates hippocampal neurogenesis in animals. However, its effect on neuronal cell differentiation remains unclear. Therefore, we investigated the effects of YKS on pluripotent P19 embryonic carcinoma cells as neuronal differentiation model cells.

Western blotting and immunocytochemistry revealed that 10 μg/mL YKS treatment during embryoid body formation or neuronal differentiation increased the expression of the neuronal stem cell marker, Nestin, by 1.9-fold and 1.7-fold, respectively, and of the mature neuron marker, NeuN, by 1.5-fold and 1.4-fold, respectively.

We examined the effect of YKS on intracellular signaling pathways in P19 cells and found significant elevation in phospho-PDK1 and phospho-mTOR expression (1.1-fold and 1.2-fold, respectively). Therefore, we investigated the effect of PDK1 and mTOR inhibitors on the level of neuronal lineage markers. We found that the mTOR inhibitor significantly abolished the YKS effect on the level of neuronal lineage markers.

Moreover, to identify the target(s) of YKS, antibody array analysis that simultaneously detects 16 phosphorylated proteins was performed. YKS significantly upregulated 10 phosphorylated proteins including PDK1, Akt, AMPK, PRAS40, mTOR, p70 S6 kinase, GSK-3α, Bad and ERK1/2 under cell proliferation conditions. These results suggest that YKS simultaneously activates multiple signaling pathways.

Thus, we concluded that YKS enhances the level of neuronal lineage markers in differentiated P19 cells, however it does not induce neuronal differentiation. Furthermore, mTOR is the predominant mediator of the YKS effect on these cells.

Dual-component collagenous peptide/reactive oligomer hydrogels as potential nerve guidance materials - from characterization to functionalization

Toward a new generation of improved nerve guidance conduits (NGCs), novel biomaterials are required to address pressing clinical shortcomings in peripheral nerve regeneration (PNR) and to promote biological performance. A dual-component hydrogel system formed by cross-linking reaction between maleic anhydride groups in an oligomeric building block for cross-linking of free amine functionalities in partially hydrolyzed collagen is formulated for continuous processing and NGC fabrication. The influence of the gelation base is optimized for processing from a double syringe delivery system with a static mixer. A hydrophilic low-concentrated base was introduced to control network formation and to utilize highly reactive macromers for gelation. Cross-linking extent and building block conversion were improved and homogenous monoliths were fabricated. Chemically derivatized hydrogels were obtained by conversion of a fraction of anhydride groups in the oligomeric precursor with monovalent primary amine-containing grafting molecules prior to gelation. Network stability in functionalized hydrogels was maintained and cationic moieties were implement to the gel that promoted in vitro cell attachment and spreading irrespective of mechanical stiffness. A molding strategy was introduced that allowed for fabrication of flexible tubular conduits in tunable dimensions and with chemically patterned structures. These hydrogel-based conduits hold promise for the next generation NGCs with integrated chemical cues for PNR.

The Emerging Role of Cdk5 in Cancer

Cdk5 is an atypical cyclin-dependent kinase that is well characterized for its role in the central nervous system rather than in the cell cycle. However Cdk5 has been recently implicated in the development and progression of a variety of cancers including breast, lung, colon, pancreatic, melanoma, thyroid and brain tumors. This broad pro-tumorigenic role makes Cdk5 a promising drug target for the development of new cancer therapies. Here we review the contribution of Cdk5 to molecular mechanisms that confer upon tumors the ability to grow, proliferate and disseminate to secondary organs, as well as resistance to chemotherapies. We subsequently discuss existing and new strategies for targeting Cdk5 and its downstream mechanisms as anti-cancer treatments.

Nestin-expressing cell types in the temporal lobe and hippocampus: Morphology, differentiation, and proliferative capacity

Nestin is expressed in immature neuroepithelial and progenitor cell types and transiently upregulated in proliferative neuroglial cells responding to acute brain injury, including following seizures. In 36 temporal lobe (TLobe) specimens from patients with TLobe epilepsy (age range 8-60 years) we studied the number, distribution and morphology of nestin-expressing cells (NEC) in the pes, hippocampus body, parahippocampal gyrus, amygdala, temporal cortex and pole compared with post mortem control tissues from 26 cases (age range 12 gestational weeks to 76 years). The proliferative fraction of NEC was evaluated in selected regions, including recognized niches, using MCM2. Their differentiation was explored with neuronal (DCX, mushashi, βIII tubulin, NeuN) and glial (GFAP, GFAPdelta, glutamine synthetase, aquaporin4, EAAT1) markers, both in sections or following culture. Findings were correlated with clinical parameters. A stereotypical pattern in the distribution and morphologies of NEC was observed, reminiscent of patterns in the developing brain, with increased densities in epilepsy than adult controls (p < .001). Findings included MCM2-positive radial glial-like cells in the periventricular white matter and rows of NEC in the hippocampal fimbria and sulcus. Nestin cells represented 29% of the hippocampal proliferative fraction in epilepsy cases; 20% co-expressed βIII tubulin in culture compared with 28% with GFAP. Significant correlations were noted between age at surgery, memory deficits and nestin populations. TLobe NEC with ongoing proliferative capacity likely represent vestiges of developmental migratory streams and resident reactive cell populations of potential relevance to hippocampal epileptogenesis, TLobe pathology, and co-morbidities, including memory decline.