ABSTRACT
Glyoxalase 1 (Glo1) is a glutathione (GSH)-dependent enzyme that catalyzes the isomerization of the hemithioacetal formed non-enzymatically from methylglyoxal (MG) and GSH to S-D-lactoylglutathione (SLG). The activity of Glo1 is measured spectrophotometrically by following the increase of absorbance at 240 nm and 25 °C, attributable to the formation of SLG. The hemithioacetal is preformed by incubation of 2 mM MG and 1 mM GSH in 0.1 M sodium phosphate buffer (PBS) pH 7.2, at 25 °C for 10 min. The cell extract is then added, and the A240 is monitored over 5-min incubation against correction for blank. Glo1 activity is given in units per mg of protein where one unit activity is defined as 1 µmole of SLG produced per min under assay conditions. Here, we describe measurement of Glo1 activity in established cellular models of cerebral cavernous malformation (CCM) disease, including KRIT1-knockout mouse embryonic fibroblast (MEF) and KRIT1-silenced human brain microvascular endothelial (hBMEC) cells.
Subject(s)
Hemangioma, Cavernous, Central Nervous System/enzymology , Lactoylglutathione Lyase/metabolism , Spectrophotometry , Animals , Enzyme Activation , Fibroblasts/enzymology , Hemangioma, Cavernous, Central Nervous System/etiology , Humans , KRIT1 Protein/genetics , KRIT1 Protein/metabolism , Lactoylglutathione Lyase/chemistry , Mice , Oxidative Stress , Spectrophotometry/methodsABSTRACT
PURPOSE: The phenotypic manifestations of cerebral cavernous malformation disease caused by rare PDCD10 mutations have not been systematically examined, and a mechanistic link to Rho kinase-mediated hyperpermeability, a potential therapeutic target, has not been established. METHODS: We analyzed PDCD10 small interfering RNA-treated endothelial cells for stress fibers, Rho kinase activity, and permeability. Rho kinase activity was assessed in cerebral cavernous malformation lesions. Brain permeability and cerebral cavernous malformation lesion burden were quantified, and clinical manifestations were assessed in prospectively enrolled subjects with PDCD10 mutations. RESULTS: We determined that PDCD10 protein suppresses endothelial stress fibers, Rho kinase activity, and permeability in vitro. Pdcd10 heterozygous mice have greater lesion burden than other Ccm genotypes. We demonstrated robust Rho kinase activity in murine and human cerebral cavernous malformation vasculature and increased brain vascular permeability in humans with PDCD10 mutation. Clinical phenotype is exceptionally aggressive compared with the more common KRIT1 and CCM2 familial and sporadic cerebral cavernous malformation, with greater lesion burden and more frequent hemorrhages earlier in life. We first report other phenotypic features, including scoliosis, cognitive disability, and skin lesions, unrelated to lesion burden or bleeding. CONCLUSION: These findings define a unique cerebral cavernous malformation disease with exceptional aggressiveness, and they inform preclinical therapeutic testing, clinical counseling, and the design of trials.Genet Med 17 3, 188-196.
Subject(s)
Apoptosis Regulatory Proteins/genetics , Central Nervous System Neoplasms/pathology , Hemangioma, Cavernous, Central Nervous System/pathology , Intracellular Signaling Peptides and Proteins/genetics , Membrane Proteins/genetics , Mutation , Proto-Oncogene Proteins/genetics , rho-Associated Kinases/metabolism , 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine/analogs & derivatives , 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine/pharmacology , Adolescent , Adult , Animals , Apoptosis Regulatory Proteins/metabolism , Carrier Proteins/genetics , Cells, Cultured , Central Nervous System Neoplasms/enzymology , Central Nervous System Neoplasms/genetics , Child , Child, Preschool , Disease Models, Animal , Hemangioma, Cavernous, Central Nervous System/enzymology , Hemangioma, Cavernous, Central Nervous System/genetics , Human Umbilical Vein Endothelial Cells , Humans , Infant , Intracellular Signaling Peptides and Proteins/metabolism , Keratin-1/genetics , Membrane Proteins/metabolism , Mice , Middle Aged , Prospective Studies , Proto-Oncogene Proteins/metabolism , Stress Fibers/drug effects , Stress Fibers/metabolism , Young Adult , rho-Associated Kinases/antagonists & inhibitorsABSTRACT
A 65-year-old man presented with a rare case of cavernous malformation with hemorrhage located within vestibular schwannoma. He had suffered hearing impairment for 20 years, and was admitted to our hospital with vertigo and ataxic gait. Neurological examination revealed hearing loss, facial nerve paresis, and left cerebellar ataxia. Magnetic resonance imaging demonstrated a left vestibular schwannoma 35 mm in diameter, as well as a heterogeneous area associated with hypointense rim within the tumor, indicating intratumoral hemorrhage. Subtotal removal of the tumor together with the fibrously encapsulated hematoma was performed through a left retrosigmoid craniotomy. Histological examination of the surgical specimen revealed cavernous malformation within vestibular schwannoma. Immunohistochemistry for matrix metalloproteinase (MMP)-2 and -9, and tissue inhibitors of metalloproteinase-2 showed strong expression in the endothelial cells of the cavernous malformation, but not in the interstitial structures. His symptoms significantly improved after surgery and he underwent gamma-knife therapy for the residual tumor. Cavernous malformations may show dynamic characteristics such as repeated hemorrhage and de novo formation. MMP-2 and -9, which are implicated in angiogenesis and hemorrhage, may be upregulated in such tumors.
Subject(s)
Cerebellar Neoplasms/enzymology , Cerebellopontine Angle , Hemangioma, Cavernous, Central Nervous System/enzymology , Matrix Metalloproteinase 2/metabolism , Matrix Metalloproteinase 9/metabolism , Neuroma, Acoustic/enzymology , Aged , Cerebellar Neoplasms/pathology , Hemangioma, Cavernous, Central Nervous System/pathology , Humans , Male , Neuroma, Acoustic/pathologyABSTRACT
Recent studies have shown that apoptosis plays an important role in vascular remodeling. We examined central nervous system vascular malformations for the presence of DNA fragmentation which is the evidence of apoptosis. We hypothesize that vascular remodeling through apoptosis may be responsible for recurrence or hemorrhage in these lesions. We examined the specimens of central nervous system vascular malformations by in situ end labeling (ISEL) of fragmented DNA. Moreover, we examined the expression of Caspase-3 which is apoptosis-related proteins in these lesions by immunohistochemistry. DNA fragmentation was observed in all 15 arteriovenous malformation (AVM) specimens. ISEL-positive cells were mainly distributed in the endothelium, media and perivascular tissue. In cavernous hemangioma (CH), DNA fragmentation was also observed in all 5 specimens. ISEL-positive cells were distributed in the endothelium, subendothelium and intercavernous matrix. Thirteen out of 15 AVM lesions stained positive for Caspase-3. Caspase-3 immunoreactivity was mainly distributed in the endothelium, media and perivascular tissue. This distribution was similar to that of ISEL positive cells. As for CHs, all 5 lesions stained positive for Caspase-3. Caspase-3 immunoreactivity was distributed in the endothelium, subendothelium and intercavernous matrix. Our findings indicate that apoptotic cell death and vascular remodeling play a role in the development and maintenance of vascular malformations.
