A Novel Mutation in LEPRE1 That Eliminates Only the KDEL ER- Retrieval Sequence Causes Non-Lethal Osteogenesis Imperfecta

Prolyl 3-hydroxylase 1 (P3H1), encoded by the LEPRE1 gene, forms a molecular complex with cartilage-associated protein (CRTAP) and cyclophilin B (encoded by PPIB) in the endoplasmic reticulum (ER). This complex is responsible for one step in collagen post-translational modification, the prolyl 3-hydroxylation of specific proline residues, specifically α1(I) Pro986. P3H1 provides the enzymatic activity of the complex and has a Lys-Asp-Glu-Leu (KDEL) ER-retrieval sequence at the carboxyl terminus. Loss of function mutations in LEPRE1 lead to the Pro986 residue remaining unmodified and lead to slow folding and excessive helical post-translational modification of type I collagen, which is seen in both dominant and recessive osteogenesis imperfecta (OI). Here, we present the case of siblings with non-lethal OI due to novel compound heterozygous mutations in LEPRE1 (c.484delG and c.2155dupC). The results of RNA analysis and real-time PCR suggest that mRNA with c.2155dupC escapes from nonsense-mediated RNA decay. Without the KDEL ER- retrieval sequence, the product of the c.2155dupC variant cannot be retained in the ER. This is the first report of a mutation in LEPRE1 that eliminates only the KDEL ER-retrieval sequence, whereas other functional domains remain intact. Our study shows, for the first time, that the KDEL ER- retrieval sequence is essential for P3H1 functionality and that a defect in KDEL is sufficient for disease onset

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De novo copy number variations (CNVs) identified in the 1210B2 iPSC-derived NSPCs. (XLSX 39 kb

The developmental programme for genesis of the entire kidney is recapitulated in Wilms tumour

<div><p>Wilms tumour (WT) is an embryonal tumour that recapitulates kidney development. The normal kidney is formed from two distinct embryological origins: the metanephric mesenchyme (MM) and the ureteric bud (UB). It is generally accepted that WT arises from precursor cells in the MM; however whether UB-equivalent structures participate in tumorigenesis is uncertain. To address the question of the involvement of UB, we assessed 55 Wilms tumours for the molecular features of MM and UB using gene expression profiling, immunohistochemsitry and immunofluorescence. Expression profiling primarily based on the Genitourinary Molecular Anatomy Project data identified molecular signatures of the UB and collecting duct as well as those of the proximal and distal tubules in the triphasic histology group. We performed immunolabeling for fetal kidneys and WTs. We focused on a central epithelial blastema pattern which is the characteristic of triphasic histology characterized by UB-like epithelial structures surrounded by MM and MM-derived epithelial structures, evoking the induction/aggregation phase of the developing kidney. The UB-like epithelial structures and surrounding MM and epithelial structures resembling early glomerular epithelium, proximal and distal tubules showed similar expression patterns to those of the developing kidney. These observations indicate WTs can arise from a precursor cell capable of generating the entire kidney, such as the cells of the intermediate mesoderm from which both the MM and UB are derived. Moreover, this provides an explanation for the variable histological features of mesenchymal to epithelial differentiation seen in WT.</p></div

Known kidney development genes differentially expressed in Triphasic tumours relative to blastemal tumours.

<p>Known kidney development genes differentially expressed in Triphasic tumours relative to blastemal tumours.</p

The developmental programme for genesis of the entire kidney is recapitulated in Wilms tumour - Fig 4

<p>Expression of WT1, MUC1, E-cadherin, CLMN, OATP-H, AQP-2, and CK-7 in the UB/CD of FK (fetal kidneys) (A, C, E, F, I, K, M, O) and that of their equivalent structures in WT (B, D, G, H, J, L, N, P). Nuclear counterstain with 4', 6-diamidino-2-phenylindole (DAPI; F, H, K, L, M, N). (A, B) Reciprocal expression of WT1 (green) and MUC-1 (red) in FK and WT. FK (A): Absence of WT1 and expression of MUC-1 in UB, with absence of MUC-1 in condensing mesenchyme (CM) and early glomerular epithelia (eGE) where WT1 is expressed (A). WT (B): MUC-1 is expressed in lumina of UB-like structures in which WT1 expression is absent. In contrast, WT1 is expressed in nuclei of RV-like tubules (arrows) in which MUC-1 expression is absent. (C, D) Expression of WT1 (green) and E-cadherin (red) in FK and WT. FK (C): Strong membranous expression of E-cadherin in the UB where WT1 expression is absent, and weak membranous expression is seen in comma-shaped bodies (CSB, red) where WT1 (green) is weakly expressed. WT (D): E-cadherin staining is strongest in the apical membrane of the WT1-negative structures compared to that in RV-like structures. (E and F, G and H) The identical expression patterns of WT1 (green) and CLMN (red) in FK (E) and WT (G), and MUC1 (green) and CLMN (red) in FK (F) and WT (H). Membranous expression of CLMN in UB-like structures in WT (G, H) as well as in the UB in FK (E, F). Absence of WT1 and expression of MUC-1 respectively highlight the UB-like epithelial structures in WT (E, G). (I and K, J and L) Expression of the GUDMAP anchor UB gene SLCO4C1 encoding OATP-H (red), WT1 (green) and MUC-1 (green) in FK (I, K) and WT (J, L). OATP-H is localized to the cell membrane of the UB where nuclear WT1 is negative and MUC-1 is positive, whereas it is expressed in the apical membrane of RV where nuclear WT1 is positive and MUC-1 is negative in FK (I, K). The expression patterns of WT1, MUC-1 and OATP-H in FK are identical to those in WT (J, L). (M, N) Expression of a collecting duct marker, AQP-2 (red) in FK and WT. AQP-2 is expressed in the apical membrane and cytoplasm of CD in FK (M) and in those of CD-like epithelial structures expressing MUC-1 (green) in WT (N). (O, P) Expression of Cytokeratin 7 (CK7, green) and MUC-1 (red) in FK and WT. Strong CK7 expression highlighting the pelvi-calyceal system in FK (O). Likewise, CK7 is also highly expressed and co-localized with MUC-1 in large ductal structures involving stratified epithelia considered to be pelvi-calyceal differentiation in WT (P). B, D, G, H, J, L are tumors with triphasic histology group and N and P are tumours with stromal-predominant histology group. Bright signals for WT1 in glomerular tufts (the nucleus of podocytes and the cytoplasm of endothelial cells of capillaries) and the cytoplasm of some stromal cells indicate that WT1 is expressed at very high levels. (A-N), original magnification x400; (O), x100; (P), x200.</p