scholarly journals Rare phenotype: Hand preaxial polydactyly associated with LRP6-related tooth agenesis in humans

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Liutao Zhang ◽  
Miao Yu ◽  
Kai Sun ◽  
Zhuangzhuang Fan ◽  
Haochen Liu ◽  
...  
Keyword(s):  
Autosomal Dominant ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Heterozygous Mutation ◽  
Tooth Agenesis ◽  
Functional Impairments ◽  
Preaxial Polydactyly ◽  
Structure Changes ◽  
Density Lipoprotein Receptor ◽  
Rare Phenotype

AbstractLow-density lipoprotein receptor-related protein 6 (LRP6) is a pathogenic gene of selective tooth agenesis-7 (OMIM#616724). Although the malformation of the digits and fore- and hindlimbs has been reported in Lrp6-deficient mice, it has been rarely discovered in humans with LRP6 mutations. Here, we demonstrate an unreported autosomal dominant LRP6 heterozygous mutation (c.2840 T > C;p.Met947Thr) in a tooth agenesis family with hand polydactyly, and another unreported autosomal dominant LRP6 heterozygous mutation (c.1154 G > C;p.Arg385Pro) in a non-syndromic tooth agenesis family. Bioinformatic prediction demonstrated the deleterious effects of the mutations, and LRP6 structure changes suggested the corresponding functional impairments. Analysis on the pattern of LRP6-related tooth agenesis demonstrated the maxillary lateral incisor was the most affected. Our study report that LRP6 mutation might be associated with hand preaxial polydactyly in humans, which broaden the phenotypic spectrum of LRP6-related disorders, and provide valuable information on the characteristics of LRP6-related tooth agenesis.

scholarly journals Investigation of a Novel LRP6 Variant Causing Autosomal-Dominant Tooth Agenesis

2021 ◽  
Vol 12 ◽  
Author(s):  
Yan-xia Huang ◽  
Chun-yan Gao ◽  
Chun-yan Zheng ◽  
Xu Chen ◽  
You-sheng Yan ◽  
...  
Keyword(s):  
In Silico ◽  
Autosomal Dominant ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Missense Variant ◽  
Tooth Agenesis ◽  
Clinical Genetic ◽  
Density Lipoprotein Receptor ◽  
Novel Variant

BackgroundThe low-density lipoprotein receptor-related protein 6 (LRP6) gene is a recently defined gene that is associated with the autosomal-dominant inherited tooth agenesis (TA). In the present study, a family of four generations having TA was recruited and subjected to a series of clinical, genetic, in silico, and in vitro investigations.MethodsAfter routine clinical evaluation, the proband was subjected to whole-exome sequencing (WES) to detect the diagnostic variant. Next, in silico structural and molecular dynamics (MD) analysis was conducted on the identified novel missense variant for predicting its intramolecular impact. Subsequently, an in vitro study was performed to further explore the effect of this variant on protein maturation and phosphorylation.ResultsWES identified a novel variant, designated as LRP6: c.2570G > A (p.R857H), harbored by six members of the concerned family, four of whom exhibited varied TA symptoms. The in silico analysis suggested that this novel variant could probably damage the Wnt bonding function of the LRP6 protein. The experimental study demonstrated that although this novel variant did not affect the LRP6 gene transcription, it caused a impairment in the maturation and phosphorylation of LRP6 protein, suggesting the possibility of the disruption of the Wnt signaling.ConclusionThe present study expanded the mutation spectrum of human TA in the LRP6 gene. The findings of the present study are insightful and conducive to understanding the functional significance of specific LRP6 variants.

New explanation for autosomal dominant high bone mass: Mutation of low-density lipoprotein receptor-related protein 6

Bone ◽  
2019 ◽  
Vol 127 ◽  
pp. 228-243 ◽  
Author(s):  
Michael P. Whyte ◽  
William H. McAlister ◽  
Fan Zhang ◽  
Vinieth N. Bijanki ◽  
Angela Nenninger ◽  
...  
Keyword(s):  
Autosomal Dominant ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Low Density ◽  
Lipoprotein Receptor ◽  
Related Protein ◽  
High Bone Mass ◽  
Density Lipoprotein Receptor ◽  
High Bone ◽  
Lipoprotein Receptor Related Protein

Lrp6 Dynamic Expression in Tooth Development and Mutations in Oligodontia

2020 ◽  
pp. 002203452097045
Author(s):  
M. Yu ◽  
Z. Fan ◽  
S.W. Wong ◽  
K. Sun ◽  
L. Zhang ◽  
...  
Keyword(s):  
Ectodermal Dysplasia ◽  
Tooth Development ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Human Tooth ◽  
Tooth Agenesis ◽  
Hypohidrotic Ectodermal Dysplasia ◽  
Functional Studies ◽  
Dynamic Expression ◽  
Density Lipoprotein Receptor

Genes associated with the WNT pathway play an important role in the etiology of tooth agenesis. Low-density lipoprotein receptor–related protein 6 encoding gene ( LRP6) is a recently defined gene that is associated with autosomal dominant inherited tooth agenesis. Here, we aimed to identify novel LRP6 mutations in patients with tooth agenesis and investigate the significance of Lrp6 during tooth development. Using whole-exome sequencing, we identified 4 novel LRP6 heterozygous mutations (c.2292G>A, c.195dup, c.1095dup, and c.1681C>T) in 4 of 77 oligodontia patients. Notably, a patient who carried a nonsense LRP6 mutation (c.2292G>A; p.W764*) presented a hypohidrotic ectodermal dysplasia phenotype. Preliminary functional studies, including bioinformatics analysis and TOP-/FOP-flash reporter assays, demonstrated that the activation of WNT/β-catenin signaling was compromised as a consequence of LRP6 mutations. RNAscope in situ hybridization revealed dynamic and special changes of Lrp6 expression during murine tooth development from E11.5 to E16.5. It was noteworthy that Lrp6 was specifically expressed in the epithelium at E11.5 to E13.5 but was expressed in both dental epithelium and dental papilla from E14.5 and persisted in both tissues at later stages. Our study broadens the mutation spectrum of human tooth agenesis and is the first to identify a LRP6 mutation in patients with hypohidrotic ectodermal dysplasia and reveal the dynamic expression pattern of Lrp6 during tooth development. Information from this study is conducive to understanding the functional significance of Lrp6 on the biological process of tooth development.

The Role of the Low-Density Lipoprotein Receptor-Related Protein (LRP) in the Plasma Clearance and Liver Uptake of Recombinant Single-chain Urokinase-type Plasminogen Activator in Rats

1997 ◽  
Vol 77 (04) ◽  
pp. 710-717 ◽  
Author(s):  
Marieke E van der Kaaden ◽  
Dingeman C Rijken ◽  
J Kar Kruijt ◽  
Theo J C van Berkel ◽  
Johan Kuiper
Keyword(s):  
Plasminogen Activator ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Single Chain ◽  
Liver Uptake ◽  
Type Plasminogen Activator ◽  
Parenchymal Liver ◽  
Urokinase Type Plasminogen Activator ◽  
Density Lipoprotein Receptor

SummaryUrokinase-type plasminogen activator (u-PA) is used as a thrombolytic agent in the treatment of acute myocardial infarction. In vitro, recombinant single-chain u-PA (rscu-PA) expressed in E.coli is recognized by the Low-Density Lipoprotein Receptor-related Protein (LRP) on rat parenchymal liver cells. In this study we investigated the role of LRP in the liver uptake and plasma clearance of rscu-PA in rats. A preinjection of the LRP inhibitor GST-RAP reduced the maximal liver uptake of 125I-rscu-PA at 5 min after injection from 50 to 30% of the injected dose and decreased the clearance of rscu-PA from 2.37 ml/min to 1.58 ml/min. Parenchymal, Kupffer and endothelial cells were responsible for 40, 50 and 10% of the liver uptake, respectively. The reduction in liver uptake of rscu-PA by the preinjection of GST-RAP was caused by a 91 % and 62% reduction in the uptake by parenchymal and Kupffer cells, respectively. In order to investigate the part of rscu-PA that accounted for the interaction with LRP, experiments were performed with a mutant of rscu-PA lacking residues 11-135 (= deltal25- rscu-PA). Deletion of residues 11-135 resulted in a 80% reduction in liver uptake and a 2.4 times slower clearance (0.97 ml/min). The parenchymal, Kupffer and endothelial cells were responsible for respectively 60, 33 and 7% of the liver uptake of 125I-deltal25-rscu-PA. Preinjection of GST-RAP completely reduced the liver uptake of delta 125-rscu-PA and reduced its clearance to 0.79 ml/min. Treatment of isolated Kupffer cells with PI-PLC reduced the binding of rscu-PA by 40%, suggesting the involvement of the urokinase-type Plasminogen Activator Receptor (u-PAR) in the recognition of rscu-PA. Our results demonstrate that in vivo LRP is responsible for more than 90% of the parenchymal liver cell mediated uptake of rscu-PA and for 60% of the Kupffer cell interaction. It is also suggested that u-PAR is involved in the Kupffer cell recognition of rscu-PA.

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