Klessner Jodi L, Desai Bhushan V, Amargo Evangeline V, Getsios Spiro, Green Kathleen J
Departments of Pathology and Dermatology, and the R. H. Lurie Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
Mol Biol Cell. 2009 Jan;20(1):328-37. doi: 10.1091/mbc.e08-04-0356. Epub 2008 Nov 5.
Regulation of classic cadherins plays a critical role in tissue remodeling during development and cancer; however, less attention has been paid to the importance of desmosomal cadherins. We previously showed that EGFR inhibition results in accumulation of the desmosomal cadherin, desmoglein 2 (Dsg2), at cell-cell interfaces accompanied by inhibition of matrix metalloprotease (MMP)-dependent shedding of the Dsg2 ectodomain and tyrosine phosphorylation of its cytoplasmic domain. Here, we show that EGFR inhibition stabilizes Dsg2 at intercellular junctions by interfering with its accumulation in an internalized cytoplasmic pool. Furthermore, MMP inhibition and ADAM17 RNAi, blocked shedding and depleted internalized Dsg2, but less so E-cadherin, in highly invasive SCC68 cells. ADAM9 and 15 silencing also impaired Dsg2 processing, supporting the idea that this desmosomal cadherin can be regulated by multiple ADAM family members. In contrast, ADAM10 siRNA enhanced accumulation of a 100-kDa Dsg2 cleavage product and internalized pool of Dsg2. Although both MMP and EGFR inhibition increased intercellular adhesive strength in control cells, the response to MMP-inhibition was Dsg2-dependent. These data support a role for endocytic trafficking in regulating desmosomal cadherin turnover and function and raise the possibility that internalization and regulation of desmosomal and classic cadherin function can be uncoupled mechanistically.
经典钙黏蛋白的调控在发育和癌症过程中的组织重塑中起着关键作用；然而，桥粒钙黏蛋白的重要性却较少受到关注。我们之前发现，表皮生长因子受体（EGFR）抑制会导致桥粒钙黏蛋白桥粒芯糖蛋白2（Dsg2）在细胞 - 细胞界面处积累，同时抑制基质金属蛋白酶（MMP）依赖的Dsg2胞外域脱落及其胞质域的酪氨酸磷酸化。在此，我们表明EGFR抑制通过干扰Dsg2在胞内池中的积累，从而在细胞间连接处稳定Dsg2。此外，在高侵袭性的SCC68细胞中，MMP抑制和ADAM17 RNA干扰可阻断Dsg2的脱落并减少其内化，但对E - 钙黏蛋白的影响较小。ADAM9和15的沉默也损害了Dsg2的加工过程，这支持了这种桥粒钙黏蛋白可由多个ADAM家族成员调控的观点。相反，ADAM10 siRNA增强了100 kDa Dsg2裂解产物的积累以及Dsg2的内化池。尽管MMP和EGFR抑制均增加了对照细胞中的细胞间黏附强度，但对MMP抑制的反应是Dsg2依赖性的。这些数据支持内吞运输在调节桥粒钙黏蛋白周转和功能中发挥作用，并提出桥粒钙黏蛋白和经典钙黏蛋白功能的内化与调控在机制上可能解偶联的可能性。
