Shyan-Yuan Kao - Academia.edu (original) (raw)
Papers by Shyan-Yuan Kao
Molecular oncology, Jan 31, 2015
Vestibular schwannomas (VSs), the most common tumors of the cerebellopontine angle, arise from Sc... more Vestibular schwannomas (VSs), the most common tumors of the cerebellopontine angle, arise from Schwann cells lining the vestibular nerve. Pharmacotherapies against VS are almost non-existent. Although the therapeutic inhibition of inflammatory modulators has been established for other neoplasms, it has not been explored in VS. A bioinformatic network analysis of all genes reported to be differentially expressed in human VS revealed a pro-inflammatory transcription factor nuclear factor-kappa B (NF-κB) as a central molecule in VS pathobiology. Assessed at the transcriptional and translational level, canonical NF-κB complex was aberrantly activated in human VS and derived VS cultures in comparison to control nerves and Schwann cells, respectively. Cultured primary VS cells and VS-derived human cell line HEI-193 were treated with specific NF-κB siRNAs, experimental NF-κB inhibitor BAY11-7082 (BAY11) and clinically relevant NF-κB inhibitor curcumin. Healthy human control Schwann cells f...
Translational research : the journal of laboratory and clinical medicine, Jan 7, 2015
Vestibular schwannomas (VSs) are the most common tumors of the cerebellopontine angle. Significan... more Vestibular schwannomas (VSs) are the most common tumors of the cerebellopontine angle. Significant clinical need exists for pharmacotherapies against VSs. Motivated by previous findings that immunohistochemical expression of cyclooxygenase 2 (COX-2) correlates with VS growth rate, we investigated the role of COX-2 in VSs and tested COX-2 inhibiting salicylates against VSs. COX-2 was found to be aberrantly expressed in human VS and primary human VS cells in comparison with control human nerve specimens and primary Schwann cells (SCs), respectively. Furthermore, levels of prostaglandin E2, the downstream enzymatic product of COX-2, were correlated with primary VS culture proliferation rate. Because COX-2 inhibiting salicylates such as aspirin are well tolerated and frequently clinically used, we assessed their repurposing for VS. Changes in proliferation, cell death, and cell viability were analyzed in primary VS cultures treated with aspirin, sodium salicylate, or 5-aminosalicylic ac...
Aging cell, Jan 21, 2016
Tumor necrosis factor (TNF) family cytokines are important mediators of inflammation. Elevated le... more Tumor necrosis factor (TNF) family cytokines are important mediators of inflammation. Elevated levels of serum TNF-α are associated with human sensorineural hearing loss via poorly understood mechanisms. We demonstrate, for the first time, expression of TNF-related apoptosis-inducing ligand (TRAIL) and its signaling death receptor 5 (DR5) in the murine inner ear and show that exogenous TRAIL can trigger hair cell and neuronal degeneration, which can be partly prevented with DR5-blocking antibodies.
F1000 - Post-publication peer review of the biomedical literature, 2010
F1000 - Post-publication peer review of the biomedical literature, 2010
Biochemical and Biophysical Research Communications, 2009
Mutation of parkin is one of the most prevalent causes of autosomal recessive Parkinson's disease... more Mutation of parkin is one of the most prevalent causes of autosomal recessive Parkinson's disease (PD). Parkin is an E3 ubiquitin ligase that acts on a variety of substrates, resulting in polyubiquitination and degradation by the proteasome or monoubiquitination and regulation of biological activity. However, the cellular functions of parkin that relate to its pathological involvement in PD are not well understood.
Biochemical and Biophysical Research Communications, 2009
Insulin-like growth factor 1 Protein aggregation a b s t r a c t While mutation of a-synuclein is... more Insulin-like growth factor 1 Protein aggregation a b s t r a c t While mutation of a-synuclein is a cause of autosomal-dominant Parkinson's disease (PD), it is still elusive as to how a-synuclein is involved in the pathogenesis of PD. Here, we show that dopamine-dependent accumulation of a-synuclein in cultured cells results in apoptosis. Furthermore, activation of insulin-like growth factor 1 (IGF-1) pathway can rescue a-synuclein toxicity and suppress a-synuclein gation appeared to be eliminated by the addition of insulin-like growth factor 1 (IGF-1), providing the potential neuroprotective effects of IGF-1 in PD.
Scientific reports, 2015
Osteoprotegerin (OPG) is a key regulator of bone remodeling. Mutations in OPG are involved in a v... more Osteoprotegerin (OPG) is a key regulator of bone remodeling. Mutations in OPG are involved in a variety of human diseases. We have shown that cochlear spiral ganglion cells secrete OPG at high levels and lack of OPG causes sensorineural hearing loss in addition to the previously described conductive hearing loss. In order to study the regulation of OPG expression, we conducted a database search on regulatory elements in the promoter region of the OPG gene, and identified two potential GATA-3 binding sites. Using luciferase assays and site directed mutagenesis, we demonstrate that these two elements are GATA-3 responsive and support GATA-3 transactivation in human HEK and HeLa cells. The expression of wild type GATA-3 activated OPG mRNA and protein expression, while the expression of a dominant negative mutant of GATA-3 or a GATA-3 shRNA construct reduced OPG mRNA and protein levels. GATA-3 deficient cells generated by expressing a GATA-3 shRNA construct were sensitive to apoptosis i...
Molecular oncology, Jan 31, 2015
Vestibular schwannomas (VSs), the most common tumors of the cerebellopontine angle, arise from Sc... more Vestibular schwannomas (VSs), the most common tumors of the cerebellopontine angle, arise from Schwann cells lining the vestibular nerve. Pharmacotherapies against VS are almost non-existent. Although the therapeutic inhibition of inflammatory modulators has been established for other neoplasms, it has not been explored in VS. A bioinformatic network analysis of all genes reported to be differentially expressed in human VS revealed a pro-inflammatory transcription factor nuclear factor-kappa B (NF-κB) as a central molecule in VS pathobiology. Assessed at the transcriptional and translational level, canonical NF-κB complex was aberrantly activated in human VS and derived VS cultures in comparison to control nerves and Schwann cells, respectively. Cultured primary VS cells and VS-derived human cell line HEI-193 were treated with specific NF-κB siRNAs, experimental NF-κB inhibitor BAY11-7082 (BAY11) and clinically relevant NF-κB inhibitor curcumin. Healthy human control Schwann cells f...
Translational research : the journal of laboratory and clinical medicine, Jan 7, 2015
Vestibular schwannomas (VSs) are the most common tumors of the cerebellopontine angle. Significan... more Vestibular schwannomas (VSs) are the most common tumors of the cerebellopontine angle. Significant clinical need exists for pharmacotherapies against VSs. Motivated by previous findings that immunohistochemical expression of cyclooxygenase 2 (COX-2) correlates with VS growth rate, we investigated the role of COX-2 in VSs and tested COX-2 inhibiting salicylates against VSs. COX-2 was found to be aberrantly expressed in human VS and primary human VS cells in comparison with control human nerve specimens and primary Schwann cells (SCs), respectively. Furthermore, levels of prostaglandin E2, the downstream enzymatic product of COX-2, were correlated with primary VS culture proliferation rate. Because COX-2 inhibiting salicylates such as aspirin are well tolerated and frequently clinically used, we assessed their repurposing for VS. Changes in proliferation, cell death, and cell viability were analyzed in primary VS cultures treated with aspirin, sodium salicylate, or 5-aminosalicylic ac...
Nature medicine, 2002
The mechanism by which dopaminergic neurons are selectively lost in Parkinson disease (PD) is unk... more The mechanism by which dopaminergic neurons are selectively lost in Parkinson disease (PD) is unknown. Here we show that accumulation of alpha-synuclein in cultured human dopaminergic neurons results in apoptosis that requires endogenous dopamine production and is mediated by reactive oxygen species. In contrast, alpha-synuclein is not toxic in non-dopaminergic human cortical neurons, but rather exhibits neuroprotective activity. Dopamine-dependent neurotoxicity is mediated by 54 83-kD soluble protein complexes that contain alpha-synuclein and 14-3-3 protein, which are elevated selectively in the substantia nigra in PD. Thus, accumulation of soluble alpha-synuclein protein complexes can render endogenous dopamine toxic, suggesting a potential mechanism for the selectivity of neuronal loss in PD.
Virology, 2001
Human T cell leukemia virus type 1 (HTLV-1) encodes a transforming protein, Tax. Tax is a promisc... more Human T cell leukemia virus type 1 (HTLV-1) encodes a transforming protein, Tax. Tax is a promiscuous viral transactivator involved in both cell growth and death control. We have previously shown that Tax sensitizes cells to apoptosis induced by DNA-damaging agents and this report further characterizes the Tax-mediated apoptosis pathway. We found that Taxmediated apoptosis in response to UV irradiation was inhibited by Bcl-2 and Bcl-X L overexpression and by treatment with the caspase inhibitor Z-VAD-FMK. Since Tax has been shown to functionally inactivate the apoptosis regulator p53, the effect of Tax on apoptosis in the absence of p53 was examined. In these studies, Tax sensitized p53-negative cells to apoptose, suggesting that Tax can mediate a p53-independent form of apoptosis. In addition, cells expressing both Tax and p53 displayed higher levels of apoptosis than cells expressing either protein alone, suggesting that the apoptosis-inducing activities of Tax and p53 are not completely overlapping. These observations demonstrate that Tax can utilize a p53independent mechanism to induce apoptotic cell death following UV irradiation.
Otolaryngology -- Head and Neck Surgery, 2011
Objective. To determine whether variations in gene expression exist at multiple subsites along th... more Objective. To determine whether variations in gene expression exist at multiple subsites along the sinonasal tract in patients with chronic sinusitis with polyps and in healthy controls.
Neurobiology of Disease, 2013
Osteoprotegerin (OPG) is a key regulator of bone remodeling. Mutations and variations in the OPG ... more Osteoprotegerin (OPG) is a key regulator of bone remodeling. Mutations and variations in the OPG gene cause many human diseases that are characterized by not only skeletal abnormalities but also poorly understood hearing loss: Paget's disease, osteoporosis, and celiac disease. To gain insight into the mechanisms of hearing loss in OPG deficiency, we studied OPG knockout (Opg −/− ) mice. We show that they develop sensorineural hearing loss, in addition to conductive hearing loss due to abnormal middle-ear bones. OPG deficiency caused demyelination and degeneration of the cochlear nerve in vivo. It also activated ERK, sensitized spiral ganglion cells (SGC) to apoptosis, and inhibited proliferation and survival of cochlear stem cells in vitro, which could be rescued by treatment with exogenous OPG, an ERK inhibitor, or bisphosphonate. Our results demonstrate a novel role for OPG in the regulation of SGC survival, and suggest a mechanism for sensorineural hearing loss in OPG deficiency.
Nature Medicine, 2002
The mechanism by which dopaminergic neurons are selectively lost in Parkinson disease (PD) is unk... more The mechanism by which dopaminergic neurons are selectively lost in Parkinson disease (PD) is unknown. Here we show that accumulation of α-synuclein in cultured human dopaminergic neurons results in apoptosis that requires endogenous dopamine production and is mediated by reactive oxygen species. In contrast, α-synuclein is not toxic in non-dopaminergic human cortical neurons, but rather exhibits neuroprotective activity. Dopamine-dependent neurotoxicity is mediated by 54-83-kD soluble protein complexes that contain α-synuclein and 14-3-3 protein, which are elevated selectively in the substantia nigra in PD. Thus, accumulation of soluble α-synuclein protein complexes can render endogenous dopamine toxic, suggesting a potential mechanism for the selectivity of neuronal loss in PD.
Nature, 2004
Whole-cell perforated recording from RGCs or tectal cells were made under visual control by metho... more Whole-cell perforated recording from RGCs or tectal cells were made under visual control by methods described previously 28 . The micropipettes were made from borosilicate glass capillaries (Kimax), had a resistance in the range of 2-3 MQ, and were tip-filled with internal solution and then were back-filled with internal solution containing 200 mg ml 21 amphotericin B. The internal solution contained: 115 mM K-gluconate, 4 mM NaCl, 1.5 mM MgCl 2 , 20 mM HEPES at pH 7.3 and 0.5 mM EGTA. Recordings were made with a patch clamp amplifier (Axopatch 200A; Axon Instruments). The whole cell capacitance was fully compensated and the series resistance (10-20 MQ) was compensated at 75-80% (lag 60 ms) and monitored during the experiment. The data were discarded if the series resistance varied by .20%. The input resistance of RGCs at 260 to 270 mV was usually in the range of 0.5 to 1 GQ. Signals were filtered at 5 kHz and sampled at 10 kHz using Axoscope software (Axon Instruments). For cell-attached recording, the pipette was filled with bath solution and a loose seal was made. To record mEPSCs from RGCs or tectal neurons, TTX (1 mM) was added to external solution. A total amount of 400 ng BDNF (PeproTech), dissolved in 15 ml bath solution containing 0.1% bovine serum albumin (BSA), was puffed into the third ventricle near the tectum through a Picospritzer II (General Valve), using a micropipette with a tip opening of 6 mm and repetitive pressure pulses (5 psi, 0.5 Hz, 1 s duration). It usually took 15 min for the BDNF-containing solution to be completely ejected. A small LCD-screen (Sony, PLM-A35) was mounted on the camera port of the microscope, allowing projection of computer-generated images onto the retina of the tadpole. Light responses were evoked by whole-field stimulations with a step (4 s) increase in the whole-field light illumination. All drugs were from Sigma.
Journal of Proteome Research, 2011
Current diagnostic tools limit a clinician's ability to discriminate between many possible causes... more Current diagnostic tools limit a clinician's ability to discriminate between many possible causes of sensorineural hearing loss. This constraint leads to the frequent diagnosis of the idiopathic condition, leaving patients without a clear prognosis and only general treatment options. As a first step toward developing new diagnostic tools and improving patient care, we report the first use of liquid chromatography-tandem mass-spectrometry (LC-MS/MS) to map the proteome of human perilymph. Using LC-MS/MS, we analyzed four samples, two collected from patients with vestibular schwannoma (VS) and two from patients undergoing cochlear implantation (CI). For each cohort, one sample contained pooled specimens collected from five patients and the second contained a specimen obtained from a single patient. Of the 271 proteins identified with high confidence among the samples, 71 proteins were common in every sample, and used to conservatively define the proteome of human perilymph. Comparison to human cerebrospinal fluid and blood plasma, as well as murine perilymph, showed significant similarity in protein content across fluids; however, a quantitative comparison was not possible. Fifteen candidate biomarkers of VS were identified by comparing VS and CI samples. This list will be used in future investigations targeted at discriminating between VS tumors associated with good versus poor hearing.
Journal of Biomedical Science, 2009
Parkinson's disease (PD) is the second most common form of human degenerative disorder. Mutation ... more Parkinson's disease (PD) is the second most common form of human degenerative disorder. Mutation of parkin is one of the most prevalent causes of autosomal recessive PD. Parkin is an E3 ubiquitin ligase that acts on a variety of substrates, resulting in polyubiquitination and degradation by the proteasome or monoubiquitination and regulation of biological activity. However, the cellular functions of parkin that relate to its pathological involvement in PD are not well understood. Here I show that parkin translocates into nucleus upon DNA damage. Nuclear translocation of parkin appears to be required to promote DNA repair. These findings suggest that DNA damage induces nuclear translocation of parkin leading to the PCNA interaction and possibly other nuclear proteins involved in DNA repair. These results suggest that parkin promotes DNA repair and protects against genotoxicity, and implicate DNA damage as a potential pathogenic mechanism in parkinsonism.
Journal of Biological Chemistry, 2000
Molecular oncology, Jan 31, 2015
Vestibular schwannomas (VSs), the most common tumors of the cerebellopontine angle, arise from Sc... more Vestibular schwannomas (VSs), the most common tumors of the cerebellopontine angle, arise from Schwann cells lining the vestibular nerve. Pharmacotherapies against VS are almost non-existent. Although the therapeutic inhibition of inflammatory modulators has been established for other neoplasms, it has not been explored in VS. A bioinformatic network analysis of all genes reported to be differentially expressed in human VS revealed a pro-inflammatory transcription factor nuclear factor-kappa B (NF-κB) as a central molecule in VS pathobiology. Assessed at the transcriptional and translational level, canonical NF-κB complex was aberrantly activated in human VS and derived VS cultures in comparison to control nerves and Schwann cells, respectively. Cultured primary VS cells and VS-derived human cell line HEI-193 were treated with specific NF-κB siRNAs, experimental NF-κB inhibitor BAY11-7082 (BAY11) and clinically relevant NF-κB inhibitor curcumin. Healthy human control Schwann cells f...
Translational research : the journal of laboratory and clinical medicine, Jan 7, 2015
Vestibular schwannomas (VSs) are the most common tumors of the cerebellopontine angle. Significan... more Vestibular schwannomas (VSs) are the most common tumors of the cerebellopontine angle. Significant clinical need exists for pharmacotherapies against VSs. Motivated by previous findings that immunohistochemical expression of cyclooxygenase 2 (COX-2) correlates with VS growth rate, we investigated the role of COX-2 in VSs and tested COX-2 inhibiting salicylates against VSs. COX-2 was found to be aberrantly expressed in human VS and primary human VS cells in comparison with control human nerve specimens and primary Schwann cells (SCs), respectively. Furthermore, levels of prostaglandin E2, the downstream enzymatic product of COX-2, were correlated with primary VS culture proliferation rate. Because COX-2 inhibiting salicylates such as aspirin are well tolerated and frequently clinically used, we assessed their repurposing for VS. Changes in proliferation, cell death, and cell viability were analyzed in primary VS cultures treated with aspirin, sodium salicylate, or 5-aminosalicylic ac...
Aging cell, Jan 21, 2016
Tumor necrosis factor (TNF) family cytokines are important mediators of inflammation. Elevated le... more Tumor necrosis factor (TNF) family cytokines are important mediators of inflammation. Elevated levels of serum TNF-α are associated with human sensorineural hearing loss via poorly understood mechanisms. We demonstrate, for the first time, expression of TNF-related apoptosis-inducing ligand (TRAIL) and its signaling death receptor 5 (DR5) in the murine inner ear and show that exogenous TRAIL can trigger hair cell and neuronal degeneration, which can be partly prevented with DR5-blocking antibodies.
F1000 - Post-publication peer review of the biomedical literature, 2010
F1000 - Post-publication peer review of the biomedical literature, 2010
Biochemical and Biophysical Research Communications, 2009
Mutation of parkin is one of the most prevalent causes of autosomal recessive Parkinson's disease... more Mutation of parkin is one of the most prevalent causes of autosomal recessive Parkinson's disease (PD). Parkin is an E3 ubiquitin ligase that acts on a variety of substrates, resulting in polyubiquitination and degradation by the proteasome or monoubiquitination and regulation of biological activity. However, the cellular functions of parkin that relate to its pathological involvement in PD are not well understood.
Biochemical and Biophysical Research Communications, 2009
Insulin-like growth factor 1 Protein aggregation a b s t r a c t While mutation of a-synuclein is... more Insulin-like growth factor 1 Protein aggregation a b s t r a c t While mutation of a-synuclein is a cause of autosomal-dominant Parkinson's disease (PD), it is still elusive as to how a-synuclein is involved in the pathogenesis of PD. Here, we show that dopamine-dependent accumulation of a-synuclein in cultured cells results in apoptosis. Furthermore, activation of insulin-like growth factor 1 (IGF-1) pathway can rescue a-synuclein toxicity and suppress a-synuclein gation appeared to be eliminated by the addition of insulin-like growth factor 1 (IGF-1), providing the potential neuroprotective effects of IGF-1 in PD.
Scientific reports, 2015
Osteoprotegerin (OPG) is a key regulator of bone remodeling. Mutations in OPG are involved in a v... more Osteoprotegerin (OPG) is a key regulator of bone remodeling. Mutations in OPG are involved in a variety of human diseases. We have shown that cochlear spiral ganglion cells secrete OPG at high levels and lack of OPG causes sensorineural hearing loss in addition to the previously described conductive hearing loss. In order to study the regulation of OPG expression, we conducted a database search on regulatory elements in the promoter region of the OPG gene, and identified two potential GATA-3 binding sites. Using luciferase assays and site directed mutagenesis, we demonstrate that these two elements are GATA-3 responsive and support GATA-3 transactivation in human HEK and HeLa cells. The expression of wild type GATA-3 activated OPG mRNA and protein expression, while the expression of a dominant negative mutant of GATA-3 or a GATA-3 shRNA construct reduced OPG mRNA and protein levels. GATA-3 deficient cells generated by expressing a GATA-3 shRNA construct were sensitive to apoptosis i...
Molecular oncology, Jan 31, 2015
Vestibular schwannomas (VSs), the most common tumors of the cerebellopontine angle, arise from Sc... more Vestibular schwannomas (VSs), the most common tumors of the cerebellopontine angle, arise from Schwann cells lining the vestibular nerve. Pharmacotherapies against VS are almost non-existent. Although the therapeutic inhibition of inflammatory modulators has been established for other neoplasms, it has not been explored in VS. A bioinformatic network analysis of all genes reported to be differentially expressed in human VS revealed a pro-inflammatory transcription factor nuclear factor-kappa B (NF-κB) as a central molecule in VS pathobiology. Assessed at the transcriptional and translational level, canonical NF-κB complex was aberrantly activated in human VS and derived VS cultures in comparison to control nerves and Schwann cells, respectively. Cultured primary VS cells and VS-derived human cell line HEI-193 were treated with specific NF-κB siRNAs, experimental NF-κB inhibitor BAY11-7082 (BAY11) and clinically relevant NF-κB inhibitor curcumin. Healthy human control Schwann cells f...
Translational research : the journal of laboratory and clinical medicine, Jan 7, 2015
Vestibular schwannomas (VSs) are the most common tumors of the cerebellopontine angle. Significan... more Vestibular schwannomas (VSs) are the most common tumors of the cerebellopontine angle. Significant clinical need exists for pharmacotherapies against VSs. Motivated by previous findings that immunohistochemical expression of cyclooxygenase 2 (COX-2) correlates with VS growth rate, we investigated the role of COX-2 in VSs and tested COX-2 inhibiting salicylates against VSs. COX-2 was found to be aberrantly expressed in human VS and primary human VS cells in comparison with control human nerve specimens and primary Schwann cells (SCs), respectively. Furthermore, levels of prostaglandin E2, the downstream enzymatic product of COX-2, were correlated with primary VS culture proliferation rate. Because COX-2 inhibiting salicylates such as aspirin are well tolerated and frequently clinically used, we assessed their repurposing for VS. Changes in proliferation, cell death, and cell viability were analyzed in primary VS cultures treated with aspirin, sodium salicylate, or 5-aminosalicylic ac...
Nature medicine, 2002
The mechanism by which dopaminergic neurons are selectively lost in Parkinson disease (PD) is unk... more The mechanism by which dopaminergic neurons are selectively lost in Parkinson disease (PD) is unknown. Here we show that accumulation of alpha-synuclein in cultured human dopaminergic neurons results in apoptosis that requires endogenous dopamine production and is mediated by reactive oxygen species. In contrast, alpha-synuclein is not toxic in non-dopaminergic human cortical neurons, but rather exhibits neuroprotective activity. Dopamine-dependent neurotoxicity is mediated by 54 83-kD soluble protein complexes that contain alpha-synuclein and 14-3-3 protein, which are elevated selectively in the substantia nigra in PD. Thus, accumulation of soluble alpha-synuclein protein complexes can render endogenous dopamine toxic, suggesting a potential mechanism for the selectivity of neuronal loss in PD.
Virology, 2001
Human T cell leukemia virus type 1 (HTLV-1) encodes a transforming protein, Tax. Tax is a promisc... more Human T cell leukemia virus type 1 (HTLV-1) encodes a transforming protein, Tax. Tax is a promiscuous viral transactivator involved in both cell growth and death control. We have previously shown that Tax sensitizes cells to apoptosis induced by DNA-damaging agents and this report further characterizes the Tax-mediated apoptosis pathway. We found that Taxmediated apoptosis in response to UV irradiation was inhibited by Bcl-2 and Bcl-X L overexpression and by treatment with the caspase inhibitor Z-VAD-FMK. Since Tax has been shown to functionally inactivate the apoptosis regulator p53, the effect of Tax on apoptosis in the absence of p53 was examined. In these studies, Tax sensitized p53-negative cells to apoptose, suggesting that Tax can mediate a p53-independent form of apoptosis. In addition, cells expressing both Tax and p53 displayed higher levels of apoptosis than cells expressing either protein alone, suggesting that the apoptosis-inducing activities of Tax and p53 are not completely overlapping. These observations demonstrate that Tax can utilize a p53independent mechanism to induce apoptotic cell death following UV irradiation.
Otolaryngology -- Head and Neck Surgery, 2011
Objective. To determine whether variations in gene expression exist at multiple subsites along th... more Objective. To determine whether variations in gene expression exist at multiple subsites along the sinonasal tract in patients with chronic sinusitis with polyps and in healthy controls.
Neurobiology of Disease, 2013
Osteoprotegerin (OPG) is a key regulator of bone remodeling. Mutations and variations in the OPG ... more Osteoprotegerin (OPG) is a key regulator of bone remodeling. Mutations and variations in the OPG gene cause many human diseases that are characterized by not only skeletal abnormalities but also poorly understood hearing loss: Paget's disease, osteoporosis, and celiac disease. To gain insight into the mechanisms of hearing loss in OPG deficiency, we studied OPG knockout (Opg −/− ) mice. We show that they develop sensorineural hearing loss, in addition to conductive hearing loss due to abnormal middle-ear bones. OPG deficiency caused demyelination and degeneration of the cochlear nerve in vivo. It also activated ERK, sensitized spiral ganglion cells (SGC) to apoptosis, and inhibited proliferation and survival of cochlear stem cells in vitro, which could be rescued by treatment with exogenous OPG, an ERK inhibitor, or bisphosphonate. Our results demonstrate a novel role for OPG in the regulation of SGC survival, and suggest a mechanism for sensorineural hearing loss in OPG deficiency.
Nature Medicine, 2002
The mechanism by which dopaminergic neurons are selectively lost in Parkinson disease (PD) is unk... more The mechanism by which dopaminergic neurons are selectively lost in Parkinson disease (PD) is unknown. Here we show that accumulation of α-synuclein in cultured human dopaminergic neurons results in apoptosis that requires endogenous dopamine production and is mediated by reactive oxygen species. In contrast, α-synuclein is not toxic in non-dopaminergic human cortical neurons, but rather exhibits neuroprotective activity. Dopamine-dependent neurotoxicity is mediated by 54-83-kD soluble protein complexes that contain α-synuclein and 14-3-3 protein, which are elevated selectively in the substantia nigra in PD. Thus, accumulation of soluble α-synuclein protein complexes can render endogenous dopamine toxic, suggesting a potential mechanism for the selectivity of neuronal loss in PD.
Nature, 2004
Whole-cell perforated recording from RGCs or tectal cells were made under visual control by metho... more Whole-cell perforated recording from RGCs or tectal cells were made under visual control by methods described previously 28 . The micropipettes were made from borosilicate glass capillaries (Kimax), had a resistance in the range of 2-3 MQ, and were tip-filled with internal solution and then were back-filled with internal solution containing 200 mg ml 21 amphotericin B. The internal solution contained: 115 mM K-gluconate, 4 mM NaCl, 1.5 mM MgCl 2 , 20 mM HEPES at pH 7.3 and 0.5 mM EGTA. Recordings were made with a patch clamp amplifier (Axopatch 200A; Axon Instruments). The whole cell capacitance was fully compensated and the series resistance (10-20 MQ) was compensated at 75-80% (lag 60 ms) and monitored during the experiment. The data were discarded if the series resistance varied by .20%. The input resistance of RGCs at 260 to 270 mV was usually in the range of 0.5 to 1 GQ. Signals were filtered at 5 kHz and sampled at 10 kHz using Axoscope software (Axon Instruments). For cell-attached recording, the pipette was filled with bath solution and a loose seal was made. To record mEPSCs from RGCs or tectal neurons, TTX (1 mM) was added to external solution. A total amount of 400 ng BDNF (PeproTech), dissolved in 15 ml bath solution containing 0.1% bovine serum albumin (BSA), was puffed into the third ventricle near the tectum through a Picospritzer II (General Valve), using a micropipette with a tip opening of 6 mm and repetitive pressure pulses (5 psi, 0.5 Hz, 1 s duration). It usually took 15 min for the BDNF-containing solution to be completely ejected. A small LCD-screen (Sony, PLM-A35) was mounted on the camera port of the microscope, allowing projection of computer-generated images onto the retina of the tadpole. Light responses were evoked by whole-field stimulations with a step (4 s) increase in the whole-field light illumination. All drugs were from Sigma.
Journal of Proteome Research, 2011
Current diagnostic tools limit a clinician's ability to discriminate between many possible causes... more Current diagnostic tools limit a clinician's ability to discriminate between many possible causes of sensorineural hearing loss. This constraint leads to the frequent diagnosis of the idiopathic condition, leaving patients without a clear prognosis and only general treatment options. As a first step toward developing new diagnostic tools and improving patient care, we report the first use of liquid chromatography-tandem mass-spectrometry (LC-MS/MS) to map the proteome of human perilymph. Using LC-MS/MS, we analyzed four samples, two collected from patients with vestibular schwannoma (VS) and two from patients undergoing cochlear implantation (CI). For each cohort, one sample contained pooled specimens collected from five patients and the second contained a specimen obtained from a single patient. Of the 271 proteins identified with high confidence among the samples, 71 proteins were common in every sample, and used to conservatively define the proteome of human perilymph. Comparison to human cerebrospinal fluid and blood plasma, as well as murine perilymph, showed significant similarity in protein content across fluids; however, a quantitative comparison was not possible. Fifteen candidate biomarkers of VS were identified by comparing VS and CI samples. This list will be used in future investigations targeted at discriminating between VS tumors associated with good versus poor hearing.
Journal of Biomedical Science, 2009
Parkinson's disease (PD) is the second most common form of human degenerative disorder. Mutation ... more Parkinson's disease (PD) is the second most common form of human degenerative disorder. Mutation of parkin is one of the most prevalent causes of autosomal recessive PD. Parkin is an E3 ubiquitin ligase that acts on a variety of substrates, resulting in polyubiquitination and degradation by the proteasome or monoubiquitination and regulation of biological activity. However, the cellular functions of parkin that relate to its pathological involvement in PD are not well understood. Here I show that parkin translocates into nucleus upon DNA damage. Nuclear translocation of parkin appears to be required to promote DNA repair. These findings suggest that DNA damage induces nuclear translocation of parkin leading to the PCNA interaction and possibly other nuclear proteins involved in DNA repair. These results suggest that parkin promotes DNA repair and protects against genotoxicity, and implicate DNA damage as a potential pathogenic mechanism in parkinsonism.
Journal of Biological Chemistry, 2000