Search results for "Knockout"

Pro-inflammatory T helper 17 directly harms oligodendrocytes in neuroinflammation.

2021

Significance Multiple sclerosis (MS) is a neuroinflammatory, demyelinating disease that represents one of the most frequent causes of irreversible disability in young adults. Treatment options to halt disability are limited. We discovered that T helper (Th)17 cells in contact with oligodendrocytes produce higher levels of glutamate and induce significantly greater oligodendrocyte damage than their Th2 counterpart. Blockade of CD29, which is linked to glutamate release pathways and expressed in high levels on Th17 cells, preserved human oligodendrocyte processes from Th17-mediated injury. Our data thus provide evidence for the direct and deleterious attack of Th17 cells on the myelin compart…

Loss of ATM sensitizes against O6-methylguanine triggered apoptosis, SCEs and chromosomal aberrations.

2003

A critical pre-cytotoxic and -apoptotic DNA lesion induced by methylating carcinogens and chemotherapeutic drugs is O6-methylguanine (O6MeG). The mechanism by which O6MeG causes cell death via apoptosis is only partially understood. The current model ascribes a role to DNA replication and mismatch repair, which converts O6MeG into a critical distal lesion (presumably a DNA double-strand break) that is finally responsible for genotoxicity and apoptosis. Here we analysed whether the PI3-like kinase ATM is involved in this process. ATM is a major player in recognizing and signaling DNA breaks, but most reports are limited to ionizing radiation. Comparing mouse ATM knockout fibroblasts (ATM-/-)…

Role of caspase-8 in hepatocyte response to infection and injury in mice.

2007

Caspase-8 has been implicated in signaling for apoptotic cell death and for certain nonapoptotic functions. However, knowledge of actual physiological or pathophysiological processes to which this enzyme contributes is lacking. Using a mouse model and employing the conditional knockout approach to delete the caspase-8 gene specifically in the liver, we found that caspase-8 deficiency in hepatocytes facilitates infection of the liver by Listeria monocytogenes, attenuates the hepatocyte proliferation wave during the first 48 hours after partial hepatectomy and, depending on the genetic background of the mice, prompts a chronic inflammatory response to the hepatectomy, as a result of which the…

Hepatocyte-specific deletion of the antiapoptotic protein myeloid cell leukemia-1 triggers proliferation and hepatocarcinogenesis in mice

2010

Regulation of hepatocellular apoptosis is crucial for liver homeostasis. Increased sensitivity of hepatocytes toward apoptosis results in chronic liver injury, whereas apoptosis resistance is linked to hepatocarcinogenesis and nonresponsiveness to therapy-induced cell death. Recently, we have demonstrated an essential role of the antiapoptotic Bcl-2 family member Myeloid cell leukemia-1 (Mcl-1) in hepatocyte survival. In mice lacking Mcl-1 specifically in hepatocytes (Mcl-1Δhep), spontaneous apoptosis caused severe liver damage. Here, we demonstrate that chronically increased apoptosis of hepatocytes coincides with strong hepatocyte proliferation resulting in hepatocellular carcinoma (HCC).…

Effect of ultraviolet light, methyl methanesulfonate and ionizing radiation on the genotoxic response and apoptosis of mouse fibroblasts lacking c-Fo…

2001

c-Fos and p53 are DNA damage-inducible proteins that are involved in gene regulation, cell cycle checkpoint control and cell proliferation following exposure to genotoxic agents. To investigate comparatively the role of c-Fos and p53 in the maintenance of genomic stability and the induction of apoptosis, we generated mouse fibroblast cell lines from knockout mice deficient for either c-fos (fos -/-) or p53 (p53-/-) or for both gene products (fosp53-/-). The sensitivity of these established cell lines was compared with the corresponding wild-type cells as to the cytotoxic, clastogenic and apoptosis-inducing effects of ultraviolet (UV-C) light and methyl methanesulfonate (MMS). Additionally, …

Priming of Leishmania-Reactive CD8+ T cells In Vivo Does Not Require LMP7-Containing Immunoproteasomes

2012

Proteasomes shape the repertoire of T cells participating in antigen-specific immune responses

2006

Differences in the cleavage specificities of constitutive proteasomes and immunoproteasomes significantly affect the generation of MHC class I ligands and therefore the activation of CD8-positive T cells. Based on these findings, we investigated whether proteasomal specificity also influences CD8-positive T cells during thymic selection by peptides derived from self proteins. We find that one of the self peptides responsible for positive selection of ovalbumin-specific OT-1 T cells, which is derived from the f-actin capping protein (Cpalpha1), is efficiently generated only by immunoproteasomes. Furthermore, OT-1 mice backcrossed onto low molecular mass protein 7 (LMP7)-deficient mice show a…

Syntaxin13 expression is regulated by mammalian target of rapamycin (mTOR) in injured neurons to promote axon regeneration.

2014

Injured peripheral neurons successfully activate intrinsic signaling pathways to enable axon regeneration. We have previously shown that dorsal root ganglia (DRG) neurons activate the mammalian target of rapamycin (mTOR) pathway following injury and that this activity enhances their axon growth capacity. mTOR plays a critical role in protein synthesis, but the mTOR-dependent proteins enhancing the regenerative capacity of DRG neurons remain unknown. To identify proteins whose expression is regulated by injury in an mTOR-dependent manner, we analyzed the protein composition of DRGs from mice in which we genetically activated mTOR and from mice with or without a prior nerve injury. Quantitati…

Increased oxidative stress and impaired antioxidant response in Lafora disease.

2014

15 páginas, 10 figuras

The substrate degradome of meprin metalloproteases reveals an unexpected proteolytic link between meprin β and ADAM10

2012

The in vivo roles of meprin metalloproteases in pathophysiological conditions remain elusive. Substrates define protease roles. Therefore, to identify natural substrates for human meprin α and β we employed TAILS (terminal amine isotopic labeling of substrates), a proteomics approach that enriches for N-terminal peptides of proteins and cleavage fragments. Of the 151 new extracellular substrates we identified, it was notable that ADAM10 (a disintegrin and metalloprotease domain-containing protein 10)—the constitutive α-secretase—is activated by meprin β through cleavage of the propeptide. To validate this cleavage event, we expressed recombinant proADAM10 and after preincubation with meprin…