Browsing by Subject "Neuroglia"
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Item Biomarkers of neurodegeneration and glial activation validated in Alzheimer’s disease assessed in longitudinal cerebrospinal fluid samples of Parkinson’s disease(PLOS, 2021-10-07) Bartl, Michael; Dakna, Mohammed; Galasko, Douglas; Hutten, Samantha J.; Foroud, Tatiana; Quan, Marian; Marek, Kenneth; Siderowf, Andrew; Franz, Jonas; Trenkwalder, Claudia; Mollenhauer, Brit; Medical and Molecular Genetics, School of MedicineAim: Several pathophysiological processes are involved in Parkinson's disease (PD) and could inform in vivo biomarkers. We assessed an established biomarker panel, validated in Alzheimer's Disease, in a PD cohort. Methods: Longitudinal cerebrospinal fluid (CSF) samples from PPMI (252 PD, 115 healthy controls, HC) were analyzed at six timepoints (baseline, 6, 12, 24, 36, and 48 months follow-up) using Elecsys® electrochemiluminescence immunoassays to quantify neurofilament light chain (NfL), soluble TREM2 receptor (sTREM2), chitinase-3-like protein 1 (YKL40), glial fibrillary acidic protein (GFAP), interleukin-6 (IL-6), S100, and total α-synuclein (αSyn). Results: αSyn was significantly lower in PD (mean 103 pg/ml vs. HC: 127 pg/ml, p<0.01; area under the curve [AUC]: 0.64), while all other biomarkers were not significantly different (AUC NfL: 0.49, sTREM2: 0.54, YKL40: 0.57, GFAP: 0.55, IL-6: 0.53, S100: 0.54, p>0.05) and none showed a significant difference longitudinally. We found significantly higher levels of all these markers between PD patients who developed cognitive decline during follow-up, except for αSyn and IL-6. Conclusion: Except for αSyn, the additional biomarkers did not differentiate PD and HC, and none showed longitudinal differences, but most markers predict cognitive decline in PD during follow-up.Item BMP Pathway and Reactive Retinal Gliosis(2013-03-06) Dharmarajan, Subramanian; Belecky-Adams, Teri; Skalnik, David Gordon; Zhang, Xin; Atkinson, SimonReactive gliosis is known to have a beneficial and a degenerative effect following injury to neurons. Although many factors have been implicated in reactive gliosis, their role in regulating this change is still unclear. We investigated the role of bone morphogenetic proteins in reactive gliosis in vivo and in vitro. In vivo, IHC analysis indicated reactive gliosis in the 6 week Ins2Akita mouse and WPK rat retinas. Expression of BMP7 was upregulated in these models, leading to an increase in the phosphorylation of downstream SMAD1. In vitro, treatment of murine retinal astrocyte cells with a strong oxidizing agent such as sodium peroxynitrite regulated RNA levels of various markers, including GFAP, CSPGs, MMPs and TIMPs. BMP7 treatment also regulated RNA levels to a similar extent, suggesting reactive gliosis. Treatment with high glucose DMEM and BMP4, however, did not elicit increase in levels to a similar degree. Increase in SMAD levels and downstream targets of SMAD signaling such as ID1, ID3 and MSX2 was also observed following treatment with sodium peroxynitrite in vitro and in the 6 week Ins2Akita mouse retinas in vivo. These data concur with previously established data which show an increase in BMP7 levels following injury. It also demonstrates a role for BMP7 in gliosis following disease. Further, it suggests SMAD signaling to play a role in initiating reactivity in astrocytes as well as in remodeling the extracellular matrix following injury and in a disease condition.Item Immunophenotypic Characterization of Germ Cell Tumor-Derived Primitive Neuroectodermal Tumors: Evidence for Frequent Neuronal and/or Glial Differentiation(Allen Press, 2021) Magers, Martin J.; Perrino, Carmen M.; Ulbright, Thomas M.; Idrees, Muhammad T.; Pathology and Laboratory Medicine, School of MedicineContext: Primitive neuroectodermal tumors (PNETs) may arise as a somatic-type malignancy in germ cell tumors. In this setting, most PNETs resemble those of the central nervous system and lack chromosome 22 translocations. However, description of the morphologic and differentiation spectrum of PNETs arising from germ cell tumors is lacking. Objective: To investigate the morphologic and immunohistochemical features of these tumors, concentrating on neuronal and glial features. Design: We selected cases based on a morphologically identifiable glial and/or differentiated neuronal component in association with the undifferentiated PNET. Immunohistochemistry for glial fibrillary acidic protein, S100 protein, synaptophysin, chromogranin A, and SOX11 was performed on tumors with available material, with the scoring of both staining intensity (0-3) and extent (0-3). Thirteen qualifying PNETs of testicular origin with available immunohistochemical stains or stainable material were identified. The complete stain panel was performed in 10 tumors. Results: SOX11 demonstrated positive staining in the undifferentiated PNET component of all tumors (10 of 10) and was rarely positive in the differentiated (ie, neuronal/glial) component (1 of 10; focal and weak); synaptophysin was slightly less sensitive in the undifferentiated component (12 of 13; often focal and weak) and also showed positivity in the neuronal/glial component (5 of 13). Glial fibrillary acidic protein and S100 were more frequently positive in the differentiated areas (83% and 77%, respectively) compared with undifferentiated areas (25% and 17%, respectively). Conclusions: SOX11 is a sensitive immunohistochemical marker for testicular PNET, particularly those lacking differentiation. Testicular PNETs often demonstrate glial and/or neuronal differentiation. Differentiation is marked by the acquisition of S100 and glial fibrillary acidic protein expression and SOX11 loss.Item mTOR regulates Aurora A via enhancing protein stability(2013-12) Fan, Li; Quilliam, Lawrence; Atkinson, Simon; Goebl, Mark G.; Harrington, Maureen A.; Wek, Ronald C.Mammalian target of rapamycin (mTOR) is a key regulator of protein synthesis. Dysregulation of mTOR signaling occurs in many human cancers and its inhibition causes arrest at the G1 cell cycle stage. However, mTOR’s impact on mitosis (M-phase) is less clear. Here, suppressing mTOR activity impacted the G2-M transition and reduced levels of M-phase kinase, Aurora A. mTOR inhibitors did not affect Aurora A mRNA levels. However, translational reporter constructs showed that mRNA containing a short, simple 5’-untranslated region (UTR), rather than a complex structure, is more responsive to mTOR inhibition. mTOR inhibitors decreased Aurora A protein amount whereas blocking proteasomal degradation rescues this phenomenon, revealing that mTOR affects Aurora A protein stability. Inhibition of protein phosphatase, PP2A, a known mTOR substrate and Aurora A partner, restored mTOR-mediated Aurora A abundance. Finally, a non-phosphorylatable Aurora A mutant was more sensitive to destruction in the presence of mTOR inhibitor. These data strongly support the notion that mTOR controls Aurora A destruction by inactivating PP2A and elevating the phosphorylation level of Ser51 in the “activation-box” of Aurora A, which dictates its sensitivity to proteasomal degradation. In summary, this study is the first to demonstrate that mTOR signaling regulates Aurora-A protein expression and stability and provides a better understanding of how mTOR regulates mitotic kinase expression and coordinates cell cycle progression. The involvement of mTOR signaling in the regulation of cell migration by its upstream activator, Rheb, was also examined. Knockdown of Rheb was found to promote F-actin reorganization and was associated with Rac1 activation and increased migration of glioma cells. Suppression of Rheb promoted platelet-derived growth factor receptor (PDGFR) expression. Pharmacological inhibition of PDGFR blocked these events. Therefore, Rheb appears to suppress tumor cell migration by inhibiting expression of growth factor receptors that in turn drive Rac1-mediate actin polymerization.Item Regeneration and plasticity of descending propriospinal neurons after transplantation of Schwann cells overexpressing glial cell line-derived neurotrophic factor following thoracic spinal cord injury in adult rats(2015-07) Deng, Lingxiao; Xu, Xiao-Ming; Sengelaub, Dale R.; Jin, Xiao-Ming; Khanna, Rajesh; Chen, JinhuiAfter spinal cord injury (SCI), poor axonal regeneration of the central nervous system, which mainly attributed to glial scar and low intrinsic regenerating capacity of severely injured neurons, causes limited functional recovery. Combinatory strategy has been applied to target multiple mechanisms. Schwann cells (SCs) have been explored as promising donors for transplantation to promote axonal regeneration. Among the central neurons, descending propriospinal neurons (DPSN) displayed the impressive regeneration response to SCs graft. Glial cell line-derived neurotrophic factor (GDNF), which receptor is widely expressed in nervous system, possesses the ability to promote neuronal survival, axonal regeneration/sprouting, remyelination, synaptic formation and modulate the glial response. We constructed a novel axonal permissive pathway in rat model of thoracic complete transection injury by grafting SCs over-expressing GDNF (SCs-GDNF) both inside and caudal to the lesion gap. Behavior evaluation and histological analyses have been applied to this study. Our results indicated that tremendous DPSN axons as well as brain stem axons regenerated across the lesion gap back to the caudal spinal cord. In addition to direct promotion on axonal regeneration, GDNF also significantly improved the astroglial environment around the lesion. These regenerations caused motor functional recovery. The dendritic plasticity of axotomized DPSN also contributed to the functional recovery. We applied a G-mutated rabies virus (G-Rabies) co-expressing green fluorescence protein (GFP) to reveal Golgi-like dendritic morphology of DPSNs and its response to axotomy injury and GDNF treatment. We also investigated the neurotransmitters phenotype of FluoroGold (FG) labeled DPSNs. Our results indicated that over 90 percent of FG-labeled DPSNs were glutamatergic neurons. DPSNs in sham animals had a predominantly dorsal-ventral distribution of dendrites. Transection injury resulted in alterations in the dendritic distribution, with dorsal-ventral retraction and lateral-medial extension of dendrites. Treatment with GDNF significantly increased the terminal dendritic length of DPSNs. The density of spine-like structures was increased after injury and treatment with GDNF enhanced this effect.