Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Department of Pediatrics, University of Cincinnati, Cincinnati, OH, United States of America.
PLoS One. 2023 Feb 21;18(2):e0281876. doi: 10.1371/journal.pone.0281876. eCollection 2023.
Neurofibromatosis Type 2 is an inherited disease characterized by Schwann cell tumors of cranial and peripheral nerves. The NF2 gene encodes Merlin, a member of the ERM family consisting of an N-terminal FERM domain, a central α-helical region, and a C-terminal domain. Changes in the intermolecular FERM-CTD interaction allow Merlin to transition between an open, FERM accessible conformation and a closed, FERM-inaccessible conformation, modulating Merlin activity. Merlin has been shown to dimerize, but the regulation and function Merlin dimerization is not clear. We used a nanobody based binding assay to show that Merlin dimerizes via a FERM-FERM interaction, orientated with each C-terminus close to each other. Patient derived and structural mutants show that dimerization controls interactions with specific binding partners, including HIPPO pathway components, and correlates with tumor suppressor activity. Gel filtration experiments showed that dimerization occurs after a PIP2 mediated transition from closed to open conformation monomers. This process requires the first 18 amino acids of the FERM domain and is inhibited by phosphorylation at serine 518. The discovery that active, open conformation Merlin is a dimer represents a new paradigm for Merlin function with implications for the development of therapies designed to compensate for Merlin loss.
神经纤维瘤病 2 型是一种遗传性疾病，其特征是颅神经和周围神经的施万细胞瘤。NF2 基因编码 Merlin，它是 ERM 家族的成员，由 N 端 FERM 结构域、中央α螺旋区和 C 端结构域组成。分子间 FERM-CTD 相互作用的改变使 Merlin 能够在开放的、FERM 可及构象和封闭的、FERM 不可及构象之间转换，从而调节 Merlin 的活性。已经表明 Merlin 能够二聚化，但其调节和功能的 Merlin 二聚化尚不清楚。我们使用基于纳米抗体的结合测定法表明， Merlin 通过 FERM-FERM 相互作用二聚化，每个 C 末端彼此靠近。源自患者的结构突变体表明，二聚化控制与特定结合伙伴的相互作用，包括 HIPPO 途径成分，并且与肿瘤抑制活性相关。凝胶过滤实验表明，二聚化发生在 PIP2 介导的从封闭到开放构象单体的转变之后。这个过程需要 FERM 结构域的前 18 个氨基酸，并且被丝氨酸 518 磷酸化所抑制。活性开放构象 Merlin 是二聚体的发现代表了 Merlin 功能的新范例，对设计旨在补偿 Merlin 缺失的治疗方法具有重要意义。
