Role of SOCS and VHL Proteins in Neuronal Differentiation and Development.

The basic helix-loop-helix factors play a central role in neuronal differentiation and nervous system development, which involve the Notch and signal transducer and activator of transcription (STAT)/small mother against decapentaplegic signaling pathways. Neural stem cells differentiate into three nervous system lineages, and the suppressor of cytokine signaling (SOCS) and von Hippel-Lindau (VHL) proteins are involved in this neuronal differentiation. The SOCS and VHL proteins both contain homologous structures comprising the BC-box motif. SOCSs recruit Elongin C, Elongin B, Cullin5(Cul5), and Rbx2, whereas VHL recruits Elongin C, Elongin B, Cul2, and Rbx1. SOCSs form SBC-Cul5/E3 complexes, and VHL forms a VBC-Cul2/E3 complex. These complexes degrade the target protein and suppress its downstream transduction pathway by acting as E3 ligases via the ubiquitin-proteasome system. The Janus kinase (JAK) is the main target protein of the E3 ligase SBC-Cul5, whereas hypoxia-inducible factor is the primary target protein of the E3 ligase VBC-Cul2; nonetheless, VBC-Cul2 also targets the JAK. SOCSs not only act on the ubiquitin-proteasome system but also act directly on JAKs to suppress the Janus kinase-signal transduction and activator of transcription (JAK-STAT) pathway. Both SOCS and VHL are expressed in the nervous system, predominantly in brain neurons in the embryonic stage. Both SOCS and VHL induce neuronal differentiation. SOCS is involved in differentiation into neurons, whereas VHL is involved in differentiation into neurons and oligodendrocytes; both proteins promote neurite outgrowth. It has also been suggested that the inactivation of these proteins may lead to the development of nervous system malignancies and that these proteins may function as tumor suppressors. The mechanism of action of SOCS and VHL involved in neuronal differentiation and nervous system development is thought to be mediated through the inhibition of downstream signaling pathways, JAK-STAT, and hypoxia-inducible factor-vascular endothelial growth factor pathways. In addition, because SOCS and VHL promote nerve regeneration, they are expected to be applied in neuronal regenerative medicine for traumatic brain injury and stroke.

SOCS7-Derived BC-Box Motif Peptide Mediated Cholinergic Differentiation of Human Adipose-Derived Mesenchymal Stem Cells.

Adipose-derived mesenchymal stem cells (ADMSCs) are a type of pluripotent somatic stem cells that differentiate into various cell types such as osteoblast, chondrocyte, and neuronal cells. ADMSCs as donor cells are used to produce regenerative medicines at hospitals and clinics. However, it has not been reported that ADMSCs were differentiated to a specific type of neuron with a peptide. Here, we report that ADMSCs differentiate to the cholinergic phenotype of neurons by the SOCS7-derived BC-box motif peptide. At operations for patients with neurological disorders, a small amount of subcutaneous fat was obtained. Two weeks later, adipose-derived mesenchymal stem cells (ADMSCs) were isolated and cultured for a further 1 to 2 weeks. Flow cytometry analysis for characterization of ADMSCs was performed with CD73, CD90, and CD105 as positive markers, and CD14, CD31, and CD56 as negative markers. The results showed that cultured cells were compatible with ADMSCs. Immunocytochemical studies showed naïve ADMSCs immunopositive for p75NTR, RET, nestin, keratin, neurofilament-M, and smooth muscle actin. ADMSCs were suggested to be pluripotent stem cells. A peptide corresponding to the amino-acid sequence of BC-box motif derived from SOCS7 protein was added to the medium at a concentration of 2 µM. Three days later, immunocytochemistry analysis, Western blot analysis, ubiquitination assay, and electrophysiological analysis with patch cramp were performed. Immunostaining revealed the expression of neurofilament H (NFH), choline acetyltransferase (ChAT), and tyrosine hydroxylase (TH). In addition, Western blot analysis showed an increase in the expression of NFH, ChAT, and TH, and the expression of ChAT was more distinct than TH. Immunoprecipitation with JAK2 showed an increase in the expression of ubiquitin. Electrophysiological analysis showed a large holding potential at the recorded cells through path electrodes. The BC-box motif peptide derived from SOCS7 promoted the cholinergic differentiation of ADMSCs. This novel method will contribute to research as well as regenerative medicine for cholinergic neuron diseases.

BC-Box Motif in SOCS6 Induces Differentiation of Epidermal Stem Cells into GABAnergic Neurons.

The BC-box motif in suppressor of cytokine signaling 6 (SOCS6) promotes the neuronal differentiation of somatic stem cells, including epidermal stem cells. SOCS6 protein belongs to the group of SOCS proteins and inhibits cytokine signaling. Here we showed that epidermal stem cells were induced to differentiate into GABAnergic neurons by the intracellular delivery of a peptide composed of the amino-acid sequences encoded by the BC-box motif in SOCS6 protein. The BC-box motif (SLQYLCRFVI) in SOCS6 corresponded to the binding site of elongin BC. GABAnergic differentiation mediated by the BC-box motif in SOCS6 protein was caused by ubiquitination of JAK2 and inhibition of the JAK2-STAT3 pathway. Furthermore, GABAnergic neuron-like cells generated from epidermal stem cells were transplanted into the brain of a rodent ischemic model. Then, we demonstrated that these transplanted cells were GAD positive and that the cognitive function of the ischemic model rodents with the transplanted cells was improved. This study could contribute to not only elucidating the mechanism of GABAnergic neuronal differentiation but also to neuronal regenerative medicine utilizing GABAnergic neurons.

Role of VHL-JAK-STAT signaling pathway in central nervous system hemangioblastoma associated with von Hippel-Lindau disease.

INTRODUCTION: Central nervous system hemangioblastoma is a benign tumor associated with or without von Hippel-Lindau (VHL) disease which is an autosomal dominant hereditary disease that results from a germline mutation in the VHL gene. A main axis of signaling pathways in central nervous system hemangioblastoma is VHL-HIF signaling pathway. Here, we propose an alternative VHL-JAK-STAT signaling pathway in hemangioblastoma and discuss the role. METHODS: Using MACS method, Scl+ hemangioblast-like cells were isolated from multipotent nestin-expressing stem cells. Then, ubiquitination of JAK2 in those cells and immunoprecipitation between JAK2 and VHL were examined. Then, expressions of JAK2 and STAT3 in those cells and expressions of VHL-associated hemangioblastoma tissues were examined. In addition, the VHL genes of patients bearing hemangioblastoma were analyzed. RESULTS: JAK2 and STAT3 in Scl+ hemangioblast-like cells were ubiquitinated after VHL- expression vector was transferred to those cells. Expressions of JAK2 and STAT3 in those cells were well recognized before the transfer, but those disappeared after the transfer. Expressions of both JAK2 and STAT3 in hemangioblastoma tissues were well shown. The VHL gene analysis revealed that patients bearing hemangioblastoma carried missense mutations in 5, small deletions in 2, large deletions in 4, and nonsense mutation in 1 CONCLUSIONS: VHL-JAK-STAT signaling pathway might play an important role in proliferation, angiogenesis, and maintenance of stem-cell-nature in hemangioblastoma as an alternative signaling pathway to supplement VHL-HIF signaling pathway.

BC-Box Motif-Mediated Neuronal Differentiation of Somatic Stem Cells.

Von Hippel-Lindau tumor suppressor protein (pVHL) functions to induce neuronal differentiation of neural stem/progenitor cells (NSCs) and skin-derived precursors (SKPs). Here we identified a neuronal differentiation domain (NDD) in pVHL. Neuronal differentiation of SKPs was induced by intracellular delivery of a peptide composed of the amino-acid sequences encoded by the NDD. Neuronal differentiation mediated by the NDD was caused by the binding between it and elongin C followed by Janus kinase-2 (JAK2) ubiquitination of JAK2 and inhibition of the JAK2/the signal transducer and activator of transcription-3(STAT)3 pathway. The NDD in pVHL contained the BC-box motif ((A,P,S,T)LXXX (A,C) XXX(A,I,L,V)) corresponding to the binding site of elongin C. Therefore, we proposed that other BC-box proteins might also contain an NDD; and subsequently also identified in them an NDD containing the amino-acid sequence encoded by the BC-box motif in BC-box proteins. Furthermore, we showed that different NDD peptide-delivered cells differentiated into different kinds of neuron-like cells. That is, dopaminergic neuron-like cells, cholinergic neuron-like cells, GABAnergic neuron-like cells or rhodopsin-positive neuron-like cells were induced by different NDD peptides. These novel findings might contribute to the development of a new method for promoting neuronal differentiation and shed further light on the mechanism of neuronal differentiation of somatic stem cells.

[Benefit of Intraoperative Mannitol Use during Endoscopic Surgery for Intracerebral Hemorrhage].

BACKGROUND: Endoscopic hematoma evacuation is an established treatment option for patients with intra- cerebral hemorrhage (ICH). The purpose of this study is to investigate the benefit of mannitol use during en- doscopic hematoma evacuation. METHODS: One hundred patients with ICH treated by endoscopic surgery from June 2009 to November 2014 were retrospectively reviewed. We divided them into mannitol administered group (n=19) and non- administered group (n=81). RESULTS: As for the patient background, surgical time, amount of intraoperative bleeding, residual hema- toma, re-operation and postoperative 30-day mortality, no significant differences were found between the two groups. CONCLUSIONS: There was no clear clinical benefit of intraoperative mannitol use during endoscopic surgery for ICH.

Intrasellar Symptomatic Salivary Gland Rest with Inflammations.

BACKGROUND: Instances of ectopic salivary gland tissue within the pituitary gland are rare, they are mostly asymptomatic, and the underlying pathophysiology of symptomatic cases is unclear. We report a case of intrasellar salivary gland rest that presented clinical symptoms and clearly related to inflammatory changes. CASE DESCRIPTION: In the present case, headache, bitemporal hemianopia, and hormone abnormality led to the detection of ectopic salivary gland tissue within the pituitary gland of a 24-year-old man. Imaging revealed a well-circumscribed intrasellar cystic lesion having a diameter of major axis of 16 mm, for which tumorectomy was performed using the nasal approach. The tumor was cystic with stringy content. Pathologic findings revealed that the lesion was composed principally of secretions lacking cell components, whereas the salivary gland tissue was found in the cyst wall. Dilated ducts due to the leakage of secretions were also observed. Acute and chronic inflammation was present around the salivary gland. CONCLUSIONS: Not only are instances of symptomatic ectopic salivary glands rare, but this was also the first case detected to be caused by the pathophysiology involving the leakage of secretions from an ectopic salivary gland and associated inflammation. We report this case to help elucidate the pathophysiology of the condition.

Isolation of multipotent nestin-expressing stem cells derived from the epidermis of elderly humans and TAT-VHL peptide-mediated neuronal differentiation of these cells.

A specialized population of cells residing in the hair follicle is quiescent but shows pluripotency for differentiating into epithelial-mesenchymal lineage cells. Therefore, such cells are hoped to be useful as implantable donor cells for regenerative therapy. Recently, it was reported that intracellular delivery of TAT-VHL peptide induces neuronal differentiation of skin-derived precursors. In the present study, we successfully isolated multipotent stem cells derived from the epidermis of elderly humans, characterized these cells as being capable of sphere formation and strong expression of nestin, fibronectin, and CD34 but not of keratin 15, and identified the niche of these cells as being the outer root sheath of the hair follicles. In addition, we showed that TAT-VHL peptide induced their neuronal differentiation in vitro, and confirmed by fluorescence immunohistochemistry the neuronal differentiation of such peptide-treated cells implanted into rodent brains. These multipotent nestin-expressing stem cells derived from human epidermis are easily accessible and should be useful as donor cells for neuronal regenerative cell therapy.

Skin-derived precursors differentiating into dopaminergic neuronal cells in the brains of Parkinson disease model rats.

OBJECT: In the authors' previous study, they observed that amino acids 157-171 of von Hippel-Lindau protein (VHL peptide) induced neuronal differentiation of skin-derived precursors. They also noted that transplantation of these differentiated cells into the striata of a Parkinson disease (PD) rat model reduced apomorphine-induced rotations. In the present study, they investigated if these cells produce dopamine in the striatum. METHODS: Skin-derived precursors were differentiated into neurons using VHL peptide and transplanted into the striata of a PD model of rats. Four weeks after transplantation, a probe was inserted into rat striata and extracellular dopamine was extracted by microdialysis. Dopamine levels were measured by high-pressure liquid chromatography. Brain sections were assessed by immunohistochemical analysis for the presence of tyrosine hydroxylase and dopamine transporter. RESULTS: Increased dopamine levels in the striata of the rats were observed after transplantation (p < 0.01), and these were correlated with a reduction in the number of apomorphine-induced rotations (p < 0.05). Skin-derived precursors observed along the tract of transplantation were positive for tyrosine hydroxylase and dopamine transporter. CONCLUSIONS: This study suggests that transplantation of skin-derived precursors, differentiated into neuronal cells using VHL peptide, can improve PD-like symptoms by enabling production of dopamine in the striata in a PD model of rats.

Engrafted VHL peptide-delivered bone marrow stromal cells promote spinal cord repair in rats.

Stem cell-based therapy using bone marrow stromal cells (MSCs) has been expected to be a promising therapy for neuronal regeneration. To repair the injured spinal cord, neuronal differentiation of MSCs before transplantation has a more satisfactory effect. Recently, neuronal differentiation of neural progenitor/stem cells by an intracellular delivery of a pVHL-derived synthetic peptide (VHL peptide) has been shown. Here, we show that VHL peptide-delivered MSCs differentiated into neuron-like cells, and that engrafted VHL peptide-delivered MSCs more recovered the behaviors of the rats than that of nondelivered MSCs. Our result suggests that the use of VHL peptide-delivered MSCs would be a promising therapeutic strategy for repairing the injured spinal cord.

Neuronal differentiation of neural progenitor cells by intracellular delivery of synthetic oligopeptide derived from Von Hippel-Lindau protein.

Intracellular delivery of synthetic oligopeptides has the potential to promote the occurrence of various cellular events such as cell death, proliferation, growth inhibition, metabolic changes, and morphological changes. However, the regulation of cellular differentiation by intracellular delivery of synthetic oligopeptides has been little studied. Von Hippel-Lindau protein (pVHL) is one of the proteins that functions to induce the differentiation of neural progenitor cells (NPCs). To function in these cells, pVHL forms a complex composed of itself, elongin BC, Clu-2, and Rbx-1. It is suggested that the binding site of elongin BC in pVHL plays a critical role in pVHL function, i.e., ubiquitination, which is related to neuronal differentiation. So, we synthesized an oligopeptide corresponding to the elongin BC binding site, and delivered the oligopeptide into NPCs by using a mixture of trifluoroacetylated lipopolyamine and diloeoyl phosphatidylethanolamine (BioPorter) to form a peptide-lipid complex. After intracellular delivery of the oligopeptide, induction of differentiation of NPCs was shown in terms of neurite outgrowth and by immunocytochemical and electrophysiological means. The intracellular delivery of the synthetic oligopeptide derived from pVHL may provide a safe and valuable approach for the neuronal differentiation of NPCs.

Transplantation of Von Hippel-Lindau peptide delivered neural stem cells promotes recovery in the injured rat spinal cord.

For transplantation of neural stem cells (NSCs) to repair the injured spinal cord, neuronal differentiation of NSCs before transplantation has more satisfactory effect because differentiation grafted NSCs are restricted to the glial lineage. Therefore, we focused on the Von Hippel-Lindau protein (VHL), which has the potential to induce neuronal differentiation of NSCs. Here, we show the transplantation of protein transduction domain-linked VHL peptide-delivered NSCs promotes the repair of the injured spinal cord. Transplantation of protein transduction domain -linked VHL peptide-delivered NSCs more recovered the behaviors of the rats than that of nondelivered NSCs, and engrafted NSCs differentiated to neuronal marker positive cells. Thus, our finding of the neuronal differentiation through VHL-peptide transfer has the great potential to cure the spinal cord injury.

Efficient generation of dopamine neuron-like cells from skin-derived precursors with a synthetic peptide derived from von Hippel-Lindau protein.

Skin-derived precursors (SKPs) from mammalian dermis represent neural crest-related stem cells capable of differentiating into both neural and mesodermal progency. SKPs are of clinical interest because they serve as accessible autologous donor cells for neuronal repair for neuronal intractable diseases. However, little is known about the efficient generation of neurons from SKPs, and phenotypes of neurons generated from SKPs have been restricted. In addition, the neuronal repair using their generated neurons as donor cells has not been achieved. The von Hippel-Lindau protein (pVHL) is one of the proteins that play an important role during neuronal differentiation, and recently neuronal differentiation of neural progenitor cells by intracellular delivery of a synthetic VHL peptide derived from elongin BC-binding site has been demonstrated. In the present study, a synthetic VHL peptide derived from elongin BC-binding site was conjugated to the protein transduction domain (PTD) of HIV-TAT protein (TATVHL peptide) to facilitate entry into cells, and we demonstrate the efficient generation of cells with dopaminergic phenotype from SKPs with the intracellular delivery of TATVHL peptide, and characterized the generated cells. The TATVHL peptide-treated SKPs expressed neuronal marker proteins, particularly dopamine neuron markers, and also up-regulated mRNA levels of proneural basic helix-loop-helix factors. After the TATVHL peptide treatment, transplanted SKPs into Parkinson's disease (PD) model rats sufficiently differentiated into dopamine neuron-like cells in PD model rats, and partially but significantly corrected behavior of PD model rats. The generated dopamine neuron-like cells are expected to serve as donor cells for neuronal repair for PD.

Transethmoidal meningoencephalocele in an elderly woman. Case report.

A 69-year-old woman presented with a transethmoidal meningoencephalocele manifesting as gradually developing anosmia. Examinations revealed a mass in the nasal cavity associated with multiple angiomas in her lip and orbit. Neuroimaging showed meningoencephalocele extending via the ethmoid sinus to the nasal cavity. She had no history of craniofacial trauma and intranasal or intracranial operation, and no skull base tumor was detected. Frontal base reconstruction was performed with a two-layer vascularized flap to prevent cerebrospinal fluid leakage. The dural defect was repaired with the pericranial flap, and the bony defect of the cribriform plate was reconstructed using the reversed U-shaped split temporalis musculofascial flap. Transethmoidal meningoencephalocele is a rare congenital malformation and almost half of the cases are identified in the first year of life. We should be aware of this clinical pathology and avoid unexpected rhinorrhea in elderly patients. The most important aspect of the operation is watertight closure of the patent passage to the intracranial compartment. The reversed U-shaped split temporalis musculofascial flap is useful to reconstruct the midline frontal base defect.

The role of von Hippel-Lindau protein in the differentiation of neural progenitor cells under normoxic and anoxic conditions.

Von Hippel-Lindau protein (pVHL) normally functions to cause ubiquitin-mediated degradation of hypoxia-inducible factor-1alpha (HIF-1alpha) under normoxic but not under hypoxic conditions, and induces neuronal differentiation of neural progenitor cells. However, the role of pVHL in the differentiation of neural progenitor cells under either condition has not been fully elucidated. Herein, we show that under the anoxic condition the expression of pVHL and neuronal markers in neural progenitor cells was inhibited, while HIF-1alpha was induced. In addition, neural progenitor cells expressing pVHL following gene transfer showed distinct neuronal differentiation and no induction of HIF-1alpha under the normoxic condition but not under the anoxic condition. In conclusion, neuronal differentiation induced by pVHL is associated with degradation of HIF-1alpha and occurs normally under the normoxic condition but not under the anoxic condition. Differentiation of neuronal progenitor cells may thus depend on oxygen density.