배경 : 전사인자인 C/EBP 은 과립구형성에 중요한 역할을 한다. 저자는 과립구형성에 관여하는 C/EBP 의 중요한 위치를 조사하였다.
방법 : C/EBP 및 핵산결합변이형인 C/EBP R211A가 포함된 레트로바이러스로 32Dcl3과 #1111세포를 감염시켰다. 감염된 32Dcl3에서 세포증식, 과립구표현인자 Gr-1 및 Mac-1과 세포분획을 조사하였다. 감염된 #1111세포는 생쥐에 주입하고 생존율을 조사하였다.
결과 : C/EBP 이 작용한 32Dcl3세포에서 2, 4, 6일에 파악한 GFP (+) 평균 세포수는 각각 244,045개, 582,938개, 873,963개이었고 Gr-1은 평균 31.3%, Mac-1은 32.6%가 발현되었으며,
미성숙세포는 평균 41.0%, 중간성숙세포는 48.3%, 성숙세포는 10.7%이었다. C/EBP R211A 경우 세포수는 707,226개, 1,106,736
개, 2,133,819개이었고, Gr-1과 Mac-1은 각각 0.1% 발현되었고, 미성숙세포는 91.7%, 중간성숙세포는 4.3%, 성숙세포는 4.0%이
었다. C/EBP 로 감염된 #1111세포를 주입한 생쥐의 평균생존 기간은 위약군에서 26.0일, 4HT (C/EBP )군 34.0일이었고, C/EBPR211A의 경우 위약군은 36.4일, 4HT (C/EBP R211A)군은
37.4일이었다.
결론 : C/EBP 은 32Dcl3세포 및 #1111세포의 증식을 억제하였으나 C/EBP R211A은 억제하지 못하였다. 또한 C/EBP 은 32Dcl3세포의 분화에 관여하였으나 C/EBP R211A은 작용이 없었다. 따라서 C/EBP 의 핵산결합부위는 과립구 분화 및 증식억제에 중요한 위치로 생각된다.
Background : The CCAAT/enhancer binding protein epsilon (C/EBP ), one of the transcription factors, plays an important role in granulopoiesis. We examined an essential site of C/EBP for granulopoiesis. Methods : 32Dcl3 cells and #1111 cells were transduced with retroviral constructs of C/EBP and C/EBP R211A (DNA binding mutant form). We examined growth rate, checked the neutrophil markers of Gr-1 and Mac-1, and counted differentiated cells in the transduced 32Dcl3 cells. The transduced #1111 cells were injected into five mice and survival times were analyzed. Results : The mean number of green fluorescent protein (GFP) (+) 32Dcl3 cells transduced with C/EBP was 244,045 at day 2, 582,938 at day 4, and 873,963 at day 6; mean expression of Gr-1 was 31.3% and Mac-1 32.6%; mean count of immature form was 41.0%, intermediate form 48.3%, and mature form 10.7%. In case of C/EBP R211A transduced 32Dcl3 cells, the respective figures were 707,226, 1,106,736, and 2,133,819; 0.1% and 0.1%; and 91.7%, 4.3%, and 4.0%. The mean survival time of #1111 cells transduced with C/EBP was 26.0 days in placebo group and 34.0 days in 4- hydroxytamoxifen (4HT; C/EBP group); in case of C/EBP R211A transduced #1111 cells, the respective figures were 36.4 and 37.4 days. Conclusions : The growth of 32Dcl3 and #1111 cells was inhibited by C/EBP , but not by C/EBP R211A. Also C/EBP was involved in the differentiation of 32Dcl3 cells, but C/EBP R211A was not. The DNA binding domain of C/EBP is a very important site for differentiating and inhibiting early myeloid cells.