Disentangling mechanisms involved in collagen pyridinoline cross-linking: The immunophilin FKBP65 is critical for dimerization of lysyl hydroxylase 2
Disentangling mechanisms involved in collagen pyridinoline cross-linking: The immunophilin FKBP65 is critical for dimerization of lysyl hydroxylase 2
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DOI：
10.1073/pnas.1600074113
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发表时间：
2016-06-28
影响因子：
11.1
通讯作者：
Bank, Ruud A.
中科院分区：
文献类型：
--
作者：
Gjaltema, Rutger A. F.;van der Stoel, Miesje M.;Bank, Ruud A.
胶原蛋白经历广泛的翻译后修饰，例如赖氨酸羟基化。Bruck综合征（BS）是一种结缔组织疾病，其特征在于在分子水平上端肽赖氨酸羟基化丧失，导致胶原吡啶啉交联减少。BS由编码赖氨酰羟化酶（LH）2或肽基脯氨酰顺反异构酶（PPIase）FKBP 65的基因突变引起。鉴于亲免素FKBP 65不显示LH活性，可能LH 2活性在某种程度上依赖于FKPB 65。在本报告中，我们提供了有关LH2和FKBP 65之间相互作用的见解。我们发现FKBP 65与LH2剪接变体LH2A和LH2B形成复合物，但不与LH1和LH3形成复合物。证实FKBP 65或LH 2的催化活性不影响络合物的形成。耗尽FKBP 65和抑制FKBP 65 PPIase活性都减少了LH 2的二聚体（活性）形式，但不影响单体（非活性）LH 2与前胶原I α 1的结合。此外，我们表明，LH2A和LH2B不能形成异二聚体彼此，但能够形成异二聚体与LH1和LH3。总的来说，我们的研究结果表明，FKBP 65连接到吡啶啉交联特异性介导的二聚LH 2。此外，FKBP 65不与LH 1和LH 3相互作用，这解释了为什么在BS中三螺旋羟基赖氨酸不受影响。我们的研究结果提供了FKBP65和吡啶啉损失之间的机制联系，并可能成为未来治疗胶原交联异常相关疾病（如纤维化和癌症）的关键。
Collagens are subjected to extensive posttranslational modifications, such as lysine hydroxylation. Bruck syndrome (BS) is a connective tissue disorder characterized at the molecular level by a loss of telopeptide lysine hydroxylation, resulting in reduced collagen pyridinoline cross-linking. BS results from mutations in the genes coding for lysyl hydroxylase (LH) 2 or peptidyl-prolyl cis-trans isomerase (PPIase) FKBP65. Given that the immunophilin FKBP65 does not exhibit LH activity, it is likely that LH2 activity is somehow dependent on FKPB65. In this report, we provide insights regarding the interplay between LH2 and FKBP65. We found that FKBP65 forms complexes with LH2 splice variants LH2A and LH2B but not with LH1 and LH3. Ablating the catalytic activity of FKBP65 or LH2 did not affect complex formation. Both depletion of FKBP65 and inhibition of FKBP65 PPIase activity reduced the dimeric (active) form of LH2 but did not affect the binding of monomeric (inactive) LH2 to procollagen I alpha 1. Furthermore, we show that LH2A and LH2B cannot form heterodimers with each other but are able to form heterodimers with LH1 and LH3. Collectively, our results indicate that FKBP65 is linked to pyridinoline cross-linking by specifically mediating the dimerization of LH2. Moreover, FKBP65 does not interact with LH1 and LH3, explaining why in BS triple-helical hydroxylysines are not affected. Our results provide a mechanistic link between FKBP65 and the loss of pyridinolines and may hold the key to future treatments for diseases related to collagen cross-linking anomalies, such as fibrosis and cancer.