Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników
Powiadomienia systemowe
  • Sesja wygasła!

Znaleziono wyników: 7

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  hamowanie apoptozy
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
Apoptosis is one of the processes of programmed cell death (PCD) in multicellular organism, and it is mediated by an intracellular proteolytic cascade. During viral infections, the host cell is the environment of the pathogen replication cycle. HEV and HCV encode proteins that prevent apoptosis. The ORF2 protein of HEV is responsible for overexpression of antiapoptotic Hsp72 in cells. Envelope glycoproteins E1 and E2 inhibit apoptosis induced by the Fas/Fas-L system. They block the activity of caspase-8 – the enzyme whose inactive form is part of DISC. The core protein HCV is a positive regulator of protein c-FLIP expression. c-FLIP prevents the conversion of caspase-8 zymogen into the mature, active form of the enzyme. NS5A inhibits the activity of p38MAPK, prevents the efflux of potassium ions from the cell, and thereby counteracts apoptosis.
Neoplastic transformation is accompanied, among others, by the inhibition of apoptosis. Four mechanisms that allow cells to avoid apoptosis are well known: loss of APAF1 (apoptosis-inducing factor 1), up-regulation of caspase inactivating apoptosis inhibitors, expression of FasL (Fas ligands) on the cell surface, and production of caspase 8 inhibiting protein (FLIP – FADD – like interleukin – 1β converting proteins). Moreover, the roles of RB1 and TP53 genes in the neoplastic process have been described. Tumor cells can show mutations of genes responsible for the expression of proteins regulating the cell cycle and of proteins controlling apoptosis, e.g. TP53 protein. Neoplastic cells seek to avoid not only apoptosis, but also necrosis, inflammatory cells, and the reaction of the immunological system. The types of neoplastic antigens, i.e. TSA (tumor specific antigens) and TAA (tumor associated antigens), as well as the possibilities of their recognition by the organism burdened with neoplasm, have been described. Furthermore, the mechanisms of weakening the immunological response by neoplastic cells and the role of inflammatory cells and inflammatory response in destroying neoplasms (mainly the cellbased response i.e. cells such as NK, LAK, Tc, Th, and macrophages) have been presented. Macrophages have received special attention because of the role of macrophages associated with tumors (e.g. mammary gland cancer in dogs) in causing an abnormal (non-canonical) course of the Wnt pathway. Paradoxically, the immune response sometimes promotes neoplastic growth by the so-called immune facilitation effect. After the first stage (i.e. the limitation of apoptosis), the necrosis of neoplastic cells and inflammatory infiltration occur, followed by unlimited neoplastic progression due to insufficient immunological anti-neoplastic cell reaction.
Previous studies have shown that mitochondria play a central role in the primary host defense mechanisms against numerous pathogens. These organelles are involved in the intrinsic pathway of apoptosis, which is one of the earliest responses to viral infection. The intrinsic pathway is tightly controlled by cellular Bcl-2 family proteins, which maintain the integrity with the outer mitochondrial membrane. Viruses have evolved multiple strategies to modulate apoptosis for their own purposes. Recent studies have discovered proteins encoded by the poxviruses, such as F1L, N1L, M11L, FPV039, ORF125, DPV022, and SPPV14, which have got a similar structure and/or functions as Bcl-2 family members. Newly identified poxviral proteins localize in mitochondria and interact with mitochondrial proteins to regulate cellular response. They are able to block the intrinsic pathway of apoptosis, and thereby allow the virus to replicate before its host cell dies.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.