健康的細(xì)胞會(huì)表達(dá)出一種小RNA,，幫助它們回避來(lái)自免疫系統(tǒng)不必要的識(shí)別和進(jìn)攻。在8月出版的《自然—免疫學(xué)》期刊上,，研究人員對(duì)這一機(jī)制進(jìn)行了解釋,，并推測(cè)腫瘤可能也利用了同樣的機(jī)制來(lái)逃逸檢測(cè)。
在遇到病毒感染等壓力狀況時(shí),，兩種蛋白質(zhì)MICA和MICB會(huì)被免疫細(xì)胞上表達(dá)的受體NKG2D所識(shí)別,。對(duì)這些由壓力誘導(dǎo)的蛋白質(zhì)的探測(cè)會(huì)觸發(fā)一種可去除壓力源的免疫反應(yīng)。而病毒則會(huì)使用一種名為小RNA的短鏈RNA來(lái)抑制MICA和MICB的表達(dá),，從而逃避相應(yīng)的免疫反應(yīng),。
以色列希伯來(lái)大學(xué)Ofer Mandelboim和同事指出，類似于這種病毒,，健康的非壓力型人類細(xì)胞也能表達(dá)出抑制MICA和MICB表達(dá)的小RNA,，因此，健康細(xì)胞能逃避免疫系統(tǒng)的探測(cè),。與健康組織相比,，人類的許多腫瘤組織也表達(dá)出過(guò)量的這類小RNA，從而讓它們逃過(guò)免疫系統(tǒng)的識(shí)別，這就是問(wèn)題的嚴(yán)重性所在,。 （生物谷Bioon.com）
生物谷推薦原始出處：
Nature Immunology,，doi:10.1038/ni.1642，Noam Stern-Ginossar,，Ofer Mandelboim
Human microRNAs regulate stress-induced immune responses mediated by the receptor NKG2D
Noam Stern-Ginossar1, Chamutal Gur1, Moshe Biton1, Elad Horwitz1, Moran Elboim1, Noa Stanietsky1, Michal Mandelboim2 & Ofer Mandelboim1
Abstract
MICA and MICB are stress-induced ligands recognized by the activating receptor NKG2D. A microRNA encoded by human cytomegalovirus downregulates MICB expression by targeting a specific site in the MICB 3' untranslated region. As this site is conserved among different MICB alleles and a similar site exists in the MICA 3' untranslated region, we speculated that these sites are targeted by cellular microRNAs. Here we identified microRNAs that bound to these MICA and MICB 3' untranslated region sequences and obtained data suggesting that these microRNAs maintain expression of MICA and MICB protein under a certain threshold and facilitate acute upregulation of MICA and MICB during cellular stress. These microRNAs were overexpressed in various tumors and we demonstrate here that they aided tumor avoidance of immune recognition.
1 Lautenberg Center for General and Tumor Immunology, The Hebrew University, The BioMedical Research Institute, Hadassah Medical School, Jerusalem 91120, Israel.
2 Clinical Virology Unit, Tel-Hashomer, Ramat Gan 52621, Israel.
