In vitro transdifferentiation of human cultured CD34+ stem cells into oligodendrocyte precursors using thyroid hormones

Developmental neurotoxicity of acrylamide and its metabolite glycidamide in a human mixed culture of neurons and astrocytes undergoing differentiation in concentrations relevant for human exposure

Neural stem cells (NSCs) derived from human induced pluripotent stem cells were used to investigate effects of exposure to the food contaminant acrylamide (AA) and its main metabolite glycidamide (GA) on key neurodevelopmental processes. Diet is an important source of human AA exposure for pregnant women, and AA is known to pass the placenta and the newborn may also be exposed through breast feeding after birth. The NSCs were exposed to AA and GA (1 ×10^-8 - 3 ×10^-3 M) under 7 days of proliferation and up to 28 days of differentiation towards a mixed culture of neurons and astrocytes. Effects on cell viability was measured using Alamar Blue™ cell viability assay, alterations in gene expression were assessed using real time PCR and RNA sequencing, and protein levels were quantified using immunocytochemistry and high content imaging. Effects of AA and GA on neurodevelopmental processes were evaluated using endpoints linked to common key events identified in the existing developmental neurotoxicity adverse outcome pathways (AOPs). Our results suggest that AA and GA at low concentrations (1 ×10^-7 - 1 ×10^-8 M) increased cell viability and markers of proliferation both in proliferating NSCs (7 days) and in maturing neurons after 14-28 days of differentiation. IC₅₀ for cell death of AA and GA was 5.2 × 10^-3 M and 5.8 × 10^-4 M, respectively, showing about ten times higher potency for GA. Increased expression of brain derived neurotrophic factor (BDNF) concomitant with decreased synaptogenesis were observed for GA exposure (10^-7 M) only at later differentiation stages, and an increased number of astrocytes (up to 3-fold) at 14 and 21 days of differentiation. Also, AA exposure gave tendency towards decreased differentiation (increased percent Nestin positive cells). After 28 days, neurite branch points and number of neurites per neuron measured by microtubule-associated protein 2 (Map2) staining decreased, while the same neurite features measured by βIII-Tubulin increased, indicating perturbation of neuronal differentiation and maturation.

Transgene and Chemical Transdifferentiation of Somatic Cells for Rapid and Efficient Neurological Disease Cell Models

For neurological diseases, molecular and cellular research relies on the use of model systems to investigate disease processes and test potential therapeutics. The last decade has witnessed an increase in the number of studies using induced pluripotent stem cells to generate disease relevant cell types from patients. The reprogramming process permits the generation of a large number of cells but is potentially disadvantaged by introducing variability in clonal lines and the removal of phenotypes of aging, which are critical to understand neurodegenerative diseases. An under-utilized approach to disease modeling involves the transdifferentiation of aged cells from patients, such as fibroblasts or blood cells, into various neural cell types. In this review we discuss techniques used for rapid and efficient direct conversion to neural cell types. We examine the limitations and future perspectives of this rapidly advancing field that could improve neurological disease modeling and drug discovery.

Novel mutations in the RING-finger domain of BRCA1 gene in clinically diagnosed breast cancer patients

In the present study, we investigated the frequency of BRCA1 gene mutations in 30 breast cancer (BC) patients of independent family history and 30 healthy control subjects. The immunohistochemistry (IHC) of BC patients showed duct cell carcinoma and distinct expression of the human epidermal growth factor receptor 2 (HER2). The genomic DNA was extracted from the BC patients and control subjects, the BRCA1 gene was PCR amplified and sequenced. The sequence analysis revealed that BRCA1 gene mutations were detected in 5/30 (16.6%) unrelated patients. One novel deleterious c.53delT mutation was detected in 3/30 (10%) unrelated patients leading to p.Met18Serfs*5 frame shift mutation in exon 2. Two patients 2/30 (6%) had novel c.297_301delinsCTCAA mutation in exon 5 leading to p.Leu99_Tyr101delinsPheSerAsn. Interestingly, the qRT-PCR analysis showed high expression of BRCA1 gene in all these patients having mutations compared with control subjects. Further, in silico analysis revealed loss of zinc-binding region of the RING-finger domain in BRCA1 structure due to these mutations, variable number of helices, helix-helix interactions, β-turns, and γ-turns were identified in the secondary structure, resulted in the formation of non-functional protein which is unable to activate BRCA1-associated genome surveillance complex (BASC) leading to uncontrolled cell proliferation. Moreover, the molecular dynamics (MD) simulations of mutated BRCA1 protein demonstrated extensive variations in the domain and non-domain regions compared with the wild-type structure as indicated by RMSD values. All these results conclusively explain that the c.53delT mutation may be the probable founder of deleterious mutation in this ethnic group.

Spinal cord injury: pathophysiology, treatment strategies, associated challenges, and future implications

Axonal regeneration and formation of tripartite (axo-glial) junctions at damaged sites is a prerequisite for early repair of injured spinal cord. Transplantation of stem cells at such sites of damage which can generate both neuronal and glial population has gained impact in terms of recuperation upon infliction with spinal cord injury. In spite of the fact that a copious number of pre-clinical studies using different stem/progenitor cells have shown promising results at acute and subacute stages, at the chronic stages of injury their recovery rates have shown a drastic decline. Therefore, developing novel therapeutic strategies are the need of the hour in order to assuage secondary morbidity and effectuate improvement of the spinal cord injury (SCI)-afflicted patients' quality of life. The present review aims at providing an overview of the current treatment strategies and also gives an insight into the potential cell-based therapies for the treatment of SCI.

Iron enhances the peptidyl deformylase activity and biofilm formation in Staphylococcus aureus

Staphylococcus aureus plays a major role in persistent infections and many of these species form structured biofilms on different surfaces which is accompanied by changes in gene expression profiles. Further, iron supplementation plays a critical role in the regulation of several protein(s)/enzyme function, which all aid in the development of active bacterial biofilms. It is well known that for each protein, deformylation is the most crucial step in biosynthesis and is catalyzed by peptidyl deformylase (PDF). Thus, the aim of the current study is to understand the role of iron in biofilm formation and deformylase activity of PDF. Hence, the PDF gene of S. aureus ATCC12600 was PCR amplified using specific primers and sequenced, followed by cloning and expression in Escherichia coli DH5α. The deformylase activity of the purified recombinant PDF was measured in culture supplemented with/without iron where the purified rPDF showed K_m of 1.3 mM and V_max of 0.035 mM/mg/min, which was close to the native PDF (K_m = 1.4 mM, V_max = 0.030 mM/mg/min). Interestingly, the K_m decreased and PDF activity increased when the culture was supplemented with iron, corroborating with qPCR results showing 100- to 150-fold more expression compared to control in S. aureus and its drug-resistant strains. Further biofilm-forming units (BU) showed an incredible increase (0.42 ± 0.005 to 6.3 ± 0.05 BU), i.e., almost 15-fold elevation in anaerobic conditions, indicating the significance of iron in S. aureus biofilms.

All Wrapped Up: Environmental Effects on Myelination

To date, studies have demonstrated the dynamic influence of exogenous environmental stimuli on multiple regions of the brain. This environmental influence positively and negatively impacts programs governing myelination, and acts on myelinating oligodendrocyte (OL) cells across the human lifespan. Developmentally, environmental manipulation of OL progenitor cells (OPCs) has profound effects on the establishment of functional cognitive, sensory, and motor programs. Furthermore, central nervous system (CNS) myelin remains an adaptive entity in adulthood, sensitive to environmentally induced structural changes. Here, we discuss the role of environmental stimuli on mechanisms governing programs of CNS myelination under normal and pathological conditions. Importantly, we highlight how these extrinsic cues can influence the intrinsic power of myelin plasticity to promote functional recovery.

Thyroid Hormone in the CNS: Contribution of Neuron-Glia Interaction

The endocrine system and the central nervous system (CNS) are intimately linked. Among hormones closely related to the nervous system, thyroid hormones (THs) are critical for the regulation of development and differentiation of neurons and neuroglia and hence for development and function of the CNS. T3 (3,3',5-triiodothyronine), an active form of TH, is important not only for neuronal development but also for differentiation of astrocytes and oligodendrocytes, and for microglial development. In adult brain, T3 affects glial morphology with sex- and age-dependent manner and therefore may affect their function, leading to influence on neuron-glia interaction. T3 is an important signaling factor that affects microglial functions such as migration and phagocytosis via complex mechanisms. Therefore, dysfunction of THs may impair glial function as well as neuronal function and thus disturb the brain, which may cause mental disorders. Investigations on molecular and cellular basis of hyperthyroidism and hypothyroidism will help us to understand changes in neuron-glia interaction and therefore consequent psychiatric symptoms.

Effect of 4-methoxy 1-methyl 2-oxopyridine 3-carbamide on Staphylococcus aureus by inhibiting UDP-MurNAc-pentapeptide, peptidyl deformylase and uridine monophosphate kinase

AIMS

The present study aimed to investigate the anti-Staphylococcus aureus and anti-biofilm properties of 4-methoxy-1-methyl-2-oxopyridine-3-carbamide (MMOXC) on S. aureus UDP-MurNAc-pentapeptide (MurF), peptidyl deformylase (PDF) and uridine monophosphate kinase (UMPK).

METHODS AND RESULTS

The in vitro efficacy of MMOXC was evaluated using quantitative polymerase chain reaction, in vitro assays and broth microdilution methods. Further, the minimum inhibitory concentration (MIC), IC₅₀ and zone of inhibition were recorded in addition to the anti-biofilm property. MMOXC inhibited pure recombinant UMPK and PDF enzymes with a K_i of 0·37 and 0·49 μmol l^-1 . However K_i was altered for MurF with varying substrates. The MurF K_i for UMT, d-Ala-d-Ala and ATP as substrates was 0·3, 0·25 and 1·4 μmol l^-1 , respectively. Real-time PCR analysis showed a significant reduction in PDF and MurF expression which correlated with the MIC₉₀ at 100 μmol l^-1 and IC₅₀ in the range 42 ± 1·5 to 50 ± 1 μmol l^-1 against all strains tested. At 5 μmol l^-1 MMOXC was able completely to remove preformed biofilms of S. aureus and other drug resistant strains.

CONCLUSIONS

MMOXC was able to kill S. aureus and drug resistant strains tested by inhibiting MurF, UMPK and PDF enzymes and completely obliterated preformed biofilms.

SIGNIFICANCE AND IMPACT OF THE STUDY

Growth reduction and biofilm removal are prerequisites for controlling S. aureus infections. In this study MMOXC exhibited prominent anti-S. aureus and anti-biofilm properties by blocking cell wall formation, RNA biosynthesis and protein maturation.

In vitro differentiation potential of human haematopoietic CD34(+) cells towards pancreatic β-cells

Haematopoietic stem cells (HSCs) possess multipotent ability to differentiate into various types of cells on providing appropriate niche. In the present study, the differentiating potential of human HSCs into β-cells of islets of langerhans was explored. Human HSCs were apheretically isolated from a donor and cultured. Phenotypic characterization of CD34 glycoprotein in the growing monolayer HSCs was confirmed by immunocytochemistry and flow cytometry techniques. HSCs were induced by selection with beta cell differentiating medium (BDM), which consists of epidermal growth factor (EGF), fibroblast growth factor (FGF), transferrin, Triiodo-l-Tyronine, nicotinamide and activin A. Distinct morphological changes of differentiated cells were observed on staining with dithizone (DTZ) and expression of PDX1, insulin and synaptophysin was confirmed by immunocytochemistry. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis revealed distinct expression of specific β-cell markers, pancreatic and duodenal homeobox-1 (PDX1), glucose transporter-2 (GLUT-2), synaptophysin (SYP) and insulin (INS) in these differentiated cells compared to HSCs. Further, these cells exhibited elevated expression of INS gene at 10 mM glucose upon inducing with different glucose concentrations. The prominent feature of the obtained β-cells was the presence of glucose sensors, which was determined by glucokinase activity and high glucokinase activity compared with CD34(+) stem cells. These findings illustrate the differentiation of CD34(+) HSCs into β-cells of islets of langerhans.

Possible role of glial cells in the relationship between thyroid dysfunction and mental disorders

It is widely accepted that there is a close relationship between the endocrine system and the central nervous system (CNS). Among hormones closely related to the nervous system, thyroid hormones (THs) are critical for the development and function of the CNS; not only for neuronal cells but also for glial development and differentiation. Any impairment of TH supply to the developing CNS causes severe and irreversible changes in the overall architecture and function of the human brain, leading to various neurological dysfunctions. In the adult brain, impairment of THs, such as hypothyroidism and hyperthyroidism, can cause psychiatric disorders such as schizophrenia, bipolar disorder, anxiety and depression. Although impact of hypothyroidism on synaptic transmission and plasticity is known, its effect on glial cells and related cellular mechanisms remain enigmatic. This mini-review article summarizes how THs are transported into the brain, metabolized in astrocytes and affect microglia and oligodendrocytes, demonstrating an example of glioendocrine system. Neuroglial effects may help to understand physiological and/or pathophysiological functions of THs in the CNS and how hypo- and hyper-thyroidism may cause mental disorders.