Tümör nekrozi̇s faktör alfa reseptör-1' i̇n (TNFR 1) klonlanmasi ve ti̇rozi̇n fosfori̇lasyonunun gösteri̇lmesi

Tumor Necrosis Factor alpha (TNF-?) is a cytokine produced during pathological conditions like cancer, viral or bacterial infection mainly by activated macrophages and T-cells and secreted into the body. TNF-? shows its biological activity by binding to trimeric receptors. One of these receptors is TNFR1, composed of 454 amino acids and contains intracytoplasmic death domain (DD). After binding to TNFR1, TNF-? induces apotosis by activating caspase-8 via DD. In addition to induction of apoptosis, activation of TNFR1 also activates NF-kB pathway via formation of intracytoplasmic NIK-IKK complex. TNFR2, which does not contain DD, can only activate NF-kB pathway. In addition to these known functions, TNF- ? also induces the activation of JAK1, JAK2, c-SRC, ERK, JNK, p38, STAT1 and STAT3. Although we know these, we dont know the molecular mechanism behind these activations. The main purpose of our study was to elucidate modifications of TNFR1 which would explain the mechanism of activation of the above mentioned signal transducers and transcription factors. In this respect, when we look at the amino acid sequence of the intracytoplasmic domain of TNFR1 we found two possible Tyrosine phosphorylation sites in the sequence of Y359AVV ve Y399SML. Tyrosine phosphorylation of TNFR1 at these sites could be basis of activation of above mentioned signal transducers. For this reason, we tested the tyrosine phosphorylation of TNFR1 after TNF-? stimulation. According to our results, TNF-? causes Tyrosine phosphorylation of TNFR1 in a time dependent manner. With this result, we think that Tyrosine phosphorylation sites of TNFR1 could serve as a point of initiation for activation of above mentioned proteins. Key words: TNF- ?, TNFR1, Apoptosis, Signal Transduction, Phosphorylation, Death Domain.