Biology subjects

Thiel, C. T.

Publications and source records attributed to Thiel, C. T..

5 recordsLinked to original sources

bioRxiv2025

LAMA5 deficiency disrupts ECM-WNT crosstalk in chondrogenesis and contributes to idiopathic short stature

Idiopathic short stature (ISS) affects 2%-3% of the population and is genetically heterogeneous, with emerging evidence implicating the extracellular matrix (ECM) of the growth plate. We identify LAMA5, encoding laminin-5, as a candidate ISS gene, with rare heterozygous variants present in 1.2% of affected individuals. To define its functional role, we generated CRISPR/Cas9-mediated LAMA5-knockout (KO) urine-derived stem cells (USCs) and induced chondrogenic differentiation in two- and three-dimensional culture systems. Loss of LAMA5 impaired chondrogenesis, with disruption of cell-cell junction programs and abnormal architecture of chondrogenic spheroids. Bulk RNA sequencing combined with weighted gene co-expression network analysis revealed WNT7A and FLI1 as key dysregulated genes within the module most strongly associated with the KO phenotype. Gene Ontology enrichment of this module highlighted embryonic limb morphogenesis as the top biological process, and WNT7A was assigned to canonical WNT signaling. Pharmacologic activation of WNT signaling using lithium chloride (LiCl) partially restored expression of WNT7A, FLI1, TFAP2A, GRHL2, and PITX1 toward wild-type levels, indicating that attenuated WNT activity is a principal downstream consequence of LAMA5 deficiency. Consistent with this, we identified an individual with ISS carrying a heterozygous PITX1 missense variant, supporting convergence of ECM (LAMA5) and transcriptional (PITX1) perturbations on a shared WNT-centered limb-morphogenesis network. Together, these findings demonstrate that laminin-5 is required for proper ECM-WNT signaling integration during human chondrogenesis and suggest that dysregulated WNT activity represents a mechanistic link between LAMA5 dysfunction and impaired endochondral growth. Partial rescue by WNT pathway re-activation highlights a potentially targetable downstream mechanism in ISS pathogenesis.

genetics↗

bioRxiv2025

Single-cell dissection of urine-derived stem cell hierarchies reveals robust chondrogenesis and clinical scalability

Developing of models of human cartilage and bone growth is essential for the study of growth disorders and to advance towards personalized therapeutic interventions. The majority of in vitro strategies depend on the use of invasively obtained mesenchymal stem cells (MSCs) or the laborious generation of induced pluripotent stem cells (iPSCs). We have now established urine-derived stem cells (USCs) as a non-invasive stem cell source capable of osteogenic and robust chondrogenic spheroid differentiation. Single-cell RNA sequencing of USCs revealed a hierarchy originating from parietal epithelial cells of the kidney, with a proliferative TOP2A subpopulation governed by MYC and E2F4 regulatory networks. Pseudo-time analysis of chondrogenic USCs uncovered alternative chondrogenic differentiation trajectories with an ALDH1A2 intermediate state and a TIMP3-expressing chondrocyte-like subpopulation as the major endpoint, exhibiting cartilage-specific gene ontologies. In conclusion, a streamlined, xeno-free culture and differentiation protocol was developed, thereby establishing the basis for clinical-grade cell expansion and cartilage matrix formation. This positions USCs as a powerful tool for studying cartilage biology and a potential platform for development and use in regenerative therapies.

genetics↗

bioRxiv2019

Prenatal diagnosis of HNF1B-associated renal cysts: Need to differentiate intragenic variants from 17q12 microdeletion syndrome?

ObjectiveLarge deletions of chromosome 17q12 (17q12DS) or intragenic variants in HNF1B are associated with variable developmental, endocrine and renal anomalies, often already noted prenatally as hyperechogenic/cystic kidneys. Here, we describe pre- and postnatal phenotypes of seven individuals with HNF1B aberrations and compare their clinical and genetic data to previous studies.\n\nMethodsPrenatal sequencing and postnatal chromosomal microarray analysis was performed in seven individuals with renal and/or neurodevelopmental phenotypes. We evaluated HNF1B-related clinical features from 82 studies and reclassified 192 reported intragenic HNF1B variants.\n\nResultsIn a prenatal case, we identified a novel in-frame deletion p.(Gly239del) within the HNF1B DNA binding domain, a mutational hotspot as demonstrated by spatial clustering analysis and high computational prediction scores. The six postnatally diagnosed individuals harbored 17q12 microdeletions of varying size. Literature screening revealed highly variable reporting of HNF1B-associated clinical traits. Overall, developmental delay was more frequent in 17q12DS carriers, although both mutation groups showed a high phenotypic heterogeneity. The reclassification of all previously reported intragenic HNF1B variants provided an up-to-date overview of the mutational spectrum.\n\nConclusionsWe highlight the value of prenatal HNF1B screening in renal developmental diseases. Standardized clinical reporting and systematic classification of HNF1B variants is necessary for a more accurate risk quantification of pre- and postnatal clinical features, improving genetic counseling and prenatal decision-making.

genetics↗

bioRxiv2018

Mutations In PIK3C2A Cause Syndromic Short Stature, Skeletal Abnormalities, and Cataracts Associated With Ciliary Dysfunction

PIK3C2A is a class II member of the phosphoinositide 3-kinase (PI3K) family that catalyzes the phosphorylation of phosphatidylinositol (PI) into PI(3)P and the phosphorylation of PI(4)P into PI(3,4)P2. We identified homozygous loss-of-function mutations in PIK3C2A in children from three independent consanguineous families with short stature, coarse facial features, cataracts with secondary glaucoma, multiple skeletal abnormalities, neurological manifestations, among other findings. Cellular studies of patient-derived fibroblasts found that they lacked PIK3C2A protein, had impaired cilia formation and function, and demonstrated reduced proliferative capacity. Collectively, the genetic and molecular data implicate mutations in PIK3C2A in a new Mendelian disorder of PI metabolism, thereby shedding light on the critical role of a class II PI3K in growth, vision, skeletal formation and neurological development. This discovery expands what is known about disorders of PI metabolism and helps unravel the role of PIK3C2A and class II PI3Ks in health and disease.

genetics↗

bioRxiv2018

The mutational and phenotypic spectrum of TUBA1A-associated tubulinopathy

BackgroundThe TUBA1A-associated tubulinopathy is clinically heterogeneous with brain malformations, microcephaly, developmental delay and epilepsy being the main clinical features. It is an autosomal dominant disorder mostly caused by de novo variants in TUBA1A.\n\nResultsIn three individuals with developmental delay we identified heterozygous de novo missense variants in TUBA1A using exome sequencing. While the c.1307G>A, p.(Gly436Asp) variant was novel, the two variants c.518C>T, p.(Pro173Leu) and c.641G>A, p.(Arg214His) were previously described. We compared the variable phenotype observed in these individuals with a carefully conducted review of the current literature and identified 166 individuals, 146 born and 20 fetuses with a TUBA1A variant. In 107 cases with available clinical information we standardized the reported phenotypes according to the Human Phenotype Ontology. The most commonly reported features were developmental delay (98%), anomalies of the corpus callosum (96%), microcephaly (76%) and lissencephaly (70%), although reporting was incomplete in the different studies. We identified a total of 121 distinct variants, including 15 recurrent ones. Missense variants cluster in the C-terminal region around the most commonly affected amino acid position Arg402 (13.3%). In a three-dimensional protein modelling, 38.6% of all disease causing variants including those in the C-terminal region are predicted to affect binding of microtubule-associated proteins or motor proteins. Genotype-phenotype analysis for recurrent variants showed an overrepresentation of certain clinical features. However, individuals with these variants are often reported in the same publication.\n\nConclusionsWith 166 individuals, we present the most comprehensive phenotypic and genotypic standardized synopsis for clinical interpretation of TUBA1A variants. Despite this considerable number, a detailed genotype-phenotype characterization is limited by large inter-study variability in reporting.

genetics↗