The DSPII splice variant is crucial for desmosome-mediated adhesion in HaCaT keratinocytes
The DSPII splice variant is crucial for desmosome-mediated adhesion in HaCaT keratinocytes
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DOI：
10.1242/jcs.084152
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发表时间：
2012-06-15
影响因子：
4
通讯作者：
Kelsell, David P.
中科院分区：
文献类型：
--
作者：
Cabral, Rita M.;Tattersall, Daniel;Kelsell, David P.
桥粒是细胞间的连接，专门用于强粘附，在表皮和心肌中突出。由于组成性桥粒基因桥粒斑蛋白（DSP）的遗传突变导致的桥粒功能缺陷导致皮肤或心脏疾病，在某些情况下两者都有。不同的突变具有不同的致病分子机制，如由影响相同蛋白质的不同结构域的突变引起的不同表型所证明的，但这些机制中的大多数仍有待确定。在这里，我们研究了DSP中的两种突变，导致两种主要DSP剪接变体DSPI和DSPII的剂量不同，并比较了它们的分子机制。其中一个突变导致总DSP单倍不足，并与常染色体显性纹状掌跖角化病（PPK）相关。另一种导致完全缺乏DSPI和次要亚型DSPIa，但DSPII水平正常，并与常染色体隐性遗传性表皮松解性PPK、羊毛状毛发和严重的致炎性扩张型心肌病相关。使用siRNA处理来模拟这两种突变以及另外的DSPII特异性siRNA，我们发现DSP同种型之间在细胞应激时角质形成细胞粘附方面的显著差异，其中DSPII是中间丝（IF）稳定性和桥粒介导的粘附的关键组分。此外，DSP表达的减少减少了斑嗜蛋白1、桥粒胶蛋白（DSC）2和DSC 3的量，DSPI对DSC 3的表达水平的影响大于DSPII。这些结果表明，这两个主要的DSP剪接变体在功能上并不完全冗余，并且DSPII剂量对于皮肤中的桥粒粘附特别重要。
Desmosomes are intercellular junctions specialised for strong adhesion that are prominent in the epidermis and heart muscle. Defective desmosomal function due to inherited mutations in the constitutive desmosomal gene desmoplakin (DSP) causes skin or heart disorders and in some instances both. Different mutations have different disease-causing molecular mechanisms as evidenced by the varying phenotypes resulting from mutations affecting different domains of the same protein, but the majority of these mechanisms remain to be determined. Here, we studied two mutations in DSP that lead to different dosages of the two major DSP splice variants, DSPI and DSPII, and compared their molecular mechanisms. One of the mutations results in total DSP haploinsufficiency and is associated with autosomal dominant striate palmoplantar keratoderma (PPK). The other leads to complete absence of DSPI and the minor isoform DSPIa but normal levels of DSPII, and is associated with autosomal recessive epidermolytic PPK, woolly hair and severe arrhythmogenic dilated cardiomyopathy. Using siRNA treatments to mimic these two mutations and additionally a DSPII-specific siRNA, we found striking differences between DSP isoforms with respect to keratinocyte adhesion upon cellular stress with DSPII being the key component in intermediate filament (IF) stability and desmosome-mediated adhesion. In addition, reduction in DSP expression reduced the amount of plakophilin 1, desmocollin (DSC) 2 and DSC3 with DSPI having a greater influence than DSPII on the expression levels of DSC3. These results suggest that the two major DSP splice variants are not completely redundant in function and that DSPII dosage is particularly important for desmosomal adhesion in the skin.