Modeling Charcot Marie Tooth 1A with Human Pluripotent Stem Cells

We have developed a defined protocol for the direct derivation and prospective isolation of Schwann cells from human embryonic and induced pluripotent stem cells. Potential uses of these cells include disease modeling, drug screening, and transplantation therapy, making it an exciting platform for translational research and personalized medicine. This method was applied to model CMT1A, a genetic peripheral neuropathy characterized by a 1.4 MB duplication on chromosome 14. Results from profiling CMT1A hiPSC-Schwann cells were validated using CMT1A PGD-hESC-Schwann cells and CMT1A iNC-Schwann cells. All three models displayed increased expression of the Peripheral Myelin Protein (PMP22) transcript, the gene believed to cause CMT1A. Two of the three models demonstrated upregulated expression of the heparan sulfate biosynthesis gene, HS3ST3b1, which is also located in the 1.4 MB CMT1A duplicated region, plays a rate limiting role in heparan sulfate fine structure biosynthesis, and whose specific role in Schwann cells is yet to be determined. Most interestingly, two pro-inflammatory cytokines, CXCL1 and MCP-1 proteins, were ultimately commonly overexpressed in all three models, and their overexpression was also confirmed in nerve biopsies from two CMT1A patients. It was also found that CMT1A Schwann cells of all three models could more readily recruit human THP-1 monocytes, and that this recruitment occurred in an MCP-1 dependent manner. Finally, through treatment with three small molecules previously identified to decrease PMP22 gene expression, we found a compound (bortezomib) that decreased both PMP22 gene and MCP-1 protein expression in Schwann cells from hiPSCs from one patient, in an example of how hiPSC-derived Schwann cells may be used for patient-specific therapeutic studies going forward. These results imply pro-inflammatory cytokine release may comprise an intrinsic and early property of nascent Schwann cells, and that immune dysregulation may be an early contributor to CMT1A pathogenesis, as opposed to a secondary reaction. Finally, the broadest contribution of this study is a methodological one, in which all three reprogrammed Schwann cell models were utilized to demonstrate a converged phenotype. This approach offers a technical alternative to genome editing for disease hiPSC phenotype validation, and comprises a feasible model for future studies

The host factor polyhedrin promoter binding protein (PPBP) is involved in transcription from the baculovirus polyhedrin gene promoter

Hypertranscription and temporal expression from the Autographa californica nuclear polyhedrosis (AcNPV) baculovirus polyhedrin promoter involves an α-amanitin-resistant RNA polymerase and requires a trans-acting viral factor(s). We previously reported that a 30-kDa host factor, polyhedrin promoter binding protein (PPBP), binds with unusual affinity, specificity, and stability to the transcriptionally important motif AATAAATAAGTATT within the polyhedrin (polh) initiator promoter and also displays coding strand-specific single-stranded DNA (ssDNA)-binding activity (S. Burma, B. Mukherjee, A. Jain, S. Habib, and S. E. Hasnain, J. Biol. Chem. 269:2750-2757, 1994; B. Mukherjee, S. Burma, and S. E. Hasnain, J. Biol. Chem. 270:4405-4411, 1995). We now present evidence which indicates that an additional factor(s) is involved in stabilizing PPBP-duplex promoter and PPBP-ssDNA interactions. TBP (TATA box binding protein) present in Spodoptera frugiperda (Sf9) cells is characteristically distinct from PPBP and does not interact directly with the polh promoter. Replacement of PPBP cognate sequences within the polh promoter with random nucleotides abolished PPBP binding in vitro and also failed to express the luciferase reporter gene in vivo. Phosphocellulose fractions of total nuclear extract from virus-infected cells which support in vitro transcription from the polh promoter contain PPBP activity. When PPBP was sequestered by the presence of oligonucleotides containing PPBP cognate sequence motifs, in vitro transcription of a C-free reporter cassette was affected but was restored by the exogenous addition of nuclear extract containing PPBP. When PPBP was mopped out in vivo by a plasmid carrying PPBP cognate sequence present in trans, polh promoter-driven expression of the luciferase reporter was abolished, demonstrating that binding of PPBP to the polh promoter is essential for transcription

Necrotizing fungal infection due to Saksenaea erythrospora: A case report and review of literature

Mucormycosis caused by Saksenaea erythrospora is an emerging infection seen with soil contamination, burns and/or nosocomial infections. PCR amplification and internal transcribed spacer sequencing is gold standard for its identification. Here, we report a case of necrotizing fungal orbital infection by S. erythrospora in an immunocompetent child

Acute visual loss with ophthalmoplegia after spinal surgery: Report of a case and review of the literature

We report a case of a 15-year-old boy who presented with profound visual loss and complete ophthalmoplegia after an uneventful spinal surgery for removal of cervical osteoblastoma. Postoperative visual loss following nonocular surgery is, fortunately rare, yet a devastating complication. The most common cause is ischemic optic neuropathy, but it can also be due to central retinal occlusion or cortical blindness. Visual loss in conjunction with ophthalmoplegia is rarely seen, and there are very few reports in the literature. We also review the related literature and highlight the mechanism and preventive measures

Lipoid proteinosis: A rare entity

Urbach–Wiethe syndrome or lipoid proteinosis is a rare autosomal recessive disorder characterized histologically by infiltration of Periodic acid Schiff-positive hyaline material in the skin, upper aerodigestive tract, eyelids, and internal organs. Classical clinical features include scarring of the skin, beaded eyelid papules (moniliform blepharosis) and laryngeal infiltration leading to hoarseness of voice. Lipoid proteinosis can lead to life-threatening conditions such as acute respiratory distress and seizures. Awareness among ophthalmologists about this rare entity is crucial for appropriate management of these patients

Efficacy of frontalis suspension with silicone rods in ptosis patients with poor Bell's phenomenon

Purpose: The purpose of the study was to evaluate the efficacy of silicone rods as frontalis sling for correction of ptosis associated with poor Bell's phenomenon in specific situations. Materials And Methods: A retrospective interventional case series of 25 eyes of 19 patients who underwent frontalis suspension surgery with silicone rods for ptosis correction from May 2006 to April 2011, was performed. Inclusion criteria included severe ptosis with poor Bell's phenomenon. Patient evaluation included clinical history and other relevant parameters of ptosis measurement. Final outcome measurements included postoperative lid height, lagophthalmos, complications, need for reoperation, and patient satisfaction. Results: Mean age at presentation was 25.72 ± 2.2 years. The sex ratio of male: female was 1.11. The causes of ptosis included chronic progressive external ophthalmoplegia (CPEO) in 11 eyes (44%), oculopharyngeal dystrophy in 2 (8%), third cranial nerve palsy in 7 (28%), traumatic in three eyes (12%), and iatrogenic postoperative ptosis (after orbital tumor excision) in two eyes (8%). The postoperative palpebral fissure height and margin reflex distance improved significantly (P = 0.0001). Extrusion of the sling and granuloma formation occurred in two eyes each, and these patients had to undergo sling removal. One patient developed mild exposure keratopathy and was managed conservatively. Conclusion: Silicone is an effective material for use in frontalis suspension in the management of severe ptosis with poor Bell's phenomenon. The elastic nature of silicone rod makes it an ideal suspensory material for patients with CPEO or third nerve palsy