Muta K, Krantz S B
Department of Medicine, Department of Veterans Affairs Medical Center, Nashville, Tennessee.
J Cell Physiol. 1995 Apr;163(1):38-50. doi: 10.1002/jcp.1041630106.
Heme synthesis by erythroid progenitor cells is maintained by erythropoietin (EP), insulin-like growth factor-I (IGF-I), and stem cell factor (SCF), and without these growth factors apoptosis (programmed cell death) occurs. To clarify the possible interaction between heme synthesis and programmed cell death of human erythroid progenitor cells, the effect of specific inhibition of heme synthesis on apoptosis of highly purified human erythroid colony forming cells (ECFC) was studied. When the amount of uncleaved DNA was determined as a measure of apoptosis, the heme synthesis inhibitors, succinylacetone (SA) (0.1 mmol/L) or isonicotinic acid hydrazide (INH) (10 mmol/L), significantly decreased the amount of uncleaved DNA (P < 0.01) in the presence of erythropoietin (EP). Addition of recombinant heavy-chain ferritin (rHF) (10 nmol/L), or deprivation of transferrin from the culture medium, which decreased heme synthesis, also reduced the amount of uncleaved DNA (P < 0.01). The production of apoptosis by diverse inhibitors of heme synthesis was in each case reversed by the addition of hemin (0.1 mmol/L) and did not occur with HL-60 cells. When the colony-forming capacity of ECFC was determined by plasma clot assay, SA, INH, or rHF reduced the number of CFU-E (P < 0.01), and the effect of SA was reversed by hemin. The addition of SA did not alter the c-myc response of ECFC to EP. These data indicate that inhibition of heme synthesis induces apoptosis of human erythroid progenitor cells, in a manner independent of an early c-myc response, and suggest that the presence of apoptosis in ineffective erythropoiesis may be secondary to impaired heme synthesis.
红细胞生成素（EP）、胰岛素样生长因子-I（IGF-I）和干细胞因子（SCF）维持红系祖细胞的血红素合成，没有这些生长因子，细胞就会发生凋亡（程序性细胞死亡）。为了阐明血红素合成与人类红系祖细胞程序性细胞死亡之间可能存在的相互作用，研究了特异性抑制血红素合成对高度纯化的人类红系集落形成细胞（ECFC）凋亡的影响。当将未切割的DNA量作为凋亡的指标进行测定时，血红素合成抑制剂琥珀酰丙酮（SA）（0.1 mmol/L）或异烟肼（INH）（10 mmol/L）在有红细胞生成素（EP）存在的情况下，显著降低了未切割的DNA量（P < 0.01）。添加重组重链铁蛋白（rHF）（10 nmol/L），或从培养基中去除转铁蛋白（这会降低血红素合成），也减少了未切割的DNA量（P < 0.01）。在每种情况下，添加血红素（0.1 mmol/L）可逆转各种血红素合成抑制剂诱导的凋亡，而HL-60细胞则未出现这种情况。当通过血浆凝块试验测定ECFC的集落形成能力时，SA、INH或rHF减少了CFU-E的数量（P < 0.01），SA的作用可被血红素逆转。添加SA并未改变ECFC对EP的c-myc反应。这些数据表明，抑制血红素合成以独立于早期c-myc反应的方式诱导人类红系祖细胞凋亡，并提示无效红细胞生成中凋亡的存在可能继发于血红素合成受损。
