Keszthelyi Tália Magdolna, Légrádi Regina, Pálya Dóra, Köles Tímea, Regős Ágnes, Karancsiné Menyhárd Dóra, Tory Kálmán
MTA-SE Lendület Nephrogenetic Research Group, Budapest, Hungary.
Pediatric Center, MTA Center of Excellence, Semmelweis University, Budapest, Hungary.
Sci Rep. 2025 Jul 22;15(1):26606. doi: 10.1038/s41598-025-10711-w.
Human podocin and C. elegans MEC-2 belong to the stomatin protein superfamily. They share 49% identity and 91% similarity both in the evolutionary conserved PHB domain (123-284 aa) and in the oligomerization region (273-351 aa). Amino acid substitutions in these conserved regions can modify the podocin oligomerization and thus the pathogenicity of trans-associated NPHS2 variants, known as interallelic interactions. The MEC-2A isoform was formerly considered to be the functional isoform and used to evaluate the effect of pathogenic podocin variants. The mec-2 mutant worms are mechanosensation deficient, and, as recently described, also chemosensation deficient. To study the interallelic interactions of podocin in vivo, we aimed to rescue the phenotype of the mec-2 mutant worm by reexpressing podocin (383 aa). However, we did not detect any chemotaxis defects in mec-2(u37) null mutants nor in mec-2(e75) missense mutants. No mechanosensation rescue was achieved by MEC-2A, but with a 17,5 kb genomic region and the MEC-2E isoform (1239 aa) with a large C-terminal. Truncating the last third of the large C-terminal abolished its rescue effect. In conclusion, the function of MEC-2 in mechanosensation requires a large C-terminal encoded by the MEC-2E isoform. Accordingly, human podocin cannot rescue the phenotype of mec-2 mutants.
人源足突蛋白和秀丽隐杆线虫的MEC-2属于stomatin蛋白超家族。它们在进化保守的PHB结构域(123 - 284个氨基酸)和寡聚化区域(273 - 351个氨基酸)中具有49%的同一性和91%的相似性。这些保守区域中的氨基酸替换可改变足突蛋白的寡聚化,进而改变反式相关NPHS2变体的致病性,即等位基因间相互作用。MEC-2A亚型以前被认为是功能亚型,并用于评估致病性足突蛋白变体的作用。mec-2突变体线虫存在机械感觉缺陷,并且,如最近所描述的,也存在化学感觉缺陷。为了在体内研究足突蛋白的等位基因间相互作用,我们旨在通过重新表达足突蛋白(383个氨基酸)来挽救mec-2突变体线虫的表型。然而,我们在mec-2(u37)缺失突变体和mec-2(e75)错义突变体中均未检测到任何趋化性缺陷。MEC-2A未能实现对机械感觉的挽救,但一个17.5 kb的基因组区域和具有大C末端的MEC-2E亚型(1239个氨基酸)可以实现。截去大C末端的最后三分之一消除了其挽救作用。总之,MEC-2在机械感觉中的功能需要由MEC-2E亚型编码的大C末端。因此,人源足突蛋白不能挽救mec-2突变体的表型。