Division of Cell Signalling and Immunology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K.
Biosci Rep. 2022 Dec 22;42(12). doi: 10.1042/BSR20221165.
Granzymes comprise a group of proteases involved in the killing of infected or cancerous cells by the immune system. Although best studied in T cells and natural killer (NK) cells, they are also expressed in some innate immune cells. Granzymes B and C are encoded in the mouse chymase locus that also encodes a number of mast cell-specific proteases. In line with this, mast cells can express granzyme B, although how this is regulated and their ability to express other granzymes is less well studied. We therefore examined how IL-33, a cytokine able to activate mast cells but not induce degranulation, regulated granzyme B and C levels in mast cells. Granzyme C, but not B, mRNA was strongly up-regulated in bone marrow-derived mast cells following IL-33 stimulation and there was a corresponding increase in granzyme C protein. These increases in both granzyme C mRNA and protein were blocked by a combination of the p38α/β MAPK inhibitor VX745 and the MEK1/2 inhibitor PD184352, which blocks the activation of ERK1/2. ERK1/2 and p38α activate the downstream kinases, mitogen and stress-activated kinases (MSK) 1 and 2, and IL-33 stimulated the phosphorylation of MSK1 and its substrate CREB in an ERK1/2 and p38-dependent manner. The promoter for granzyme C contains a potential CREB-binding site. Bone marrow-derived mast cells from either MSK1/2 double knockout or CREB Ser133Ala knockin mice were unable to up-regulate granzyme C. Together these results indicate that IL-33-induced granzyme C expression in mast cells is regulated by an MSK1/2-CREB-dependent pathway.
颗粒酶属于一组蛋白酶，参与免疫系统杀死感染或癌变的细胞。虽然在 T 细胞和自然杀伤 (NK) 细胞中研究得最多，但它们也在一些固有免疫细胞中表达。颗粒酶 B 和 C 编码在小鼠糜酶基因座中，该基因座还编码许多肥大细胞特异性蛋白酶。与此一致，肥大细胞可以表达颗粒酶 B，尽管其调控方式以及表达其他颗粒酶的能力研究得较少。因此，我们研究了白细胞介素-33（一种能够激活肥大细胞但不能诱导脱颗粒的细胞因子）如何调节肥大细胞中的颗粒酶 B 和 C 水平。在白细胞介素-33刺激后，骨髓来源的肥大细胞中颗粒酶 C，但不是 B 的 mRNA 强烈上调，并且颗粒酶 C 蛋白相应增加。这两种颗粒酶 C mRNA 和蛋白的增加都被 p38α/β MAPK 抑制剂 VX745 和 MEK1/2 抑制剂 PD184352 的组合阻断，该组合阻断了 ERK1/2 的激活。ERK1/2 和 p38α 激活下游激酶丝裂原和应激激活激酶 (MSK) 1 和 2，白细胞介素-33 以 ERK1/2 和 p38 依赖的方式刺激 MSK1 和其底物 CREB 的磷酸化。颗粒酶 C 的启动子含有一个潜在的 CREB 结合位点。来自 MSK1/2 双敲除或 CREB Ser133Ala 敲入小鼠的骨髓来源的肥大细胞都无法上调颗粒酶 C。这些结果表明，白细胞介素-33 诱导的肥大细胞中颗粒酶 C 的表达受 MSK1/2-CREB 依赖性途径调节。
