Biology subjects

Gurnett, C.

Publications and source records attributed to Gurnett, C..

4 recordsLinked to original sources

bioRxiv2023

Association of an estrogen-sensitive Pax1-Col11a1-Mmp3 signaling axis with adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis (AIS) is a common and progressive spinal deformity in children that exhibits striking sexual dimorphism, with girls at more than five-fold greater risk of severe disease compared to boys. Despite its medical impact, the molecular mechanisms that drive AIS are largely unknown. We previously defined a female-specific AIS genetic risk locus in an enhancer near the PAX1 gene. Here we sought to define the roles of PAX1 and newly-identified AIS-associated genes in the developmental mechanism of AIS. In a genetic study of 10,519 individuals with AIS and 93,238 unaffected controls, significant association was identified with a variant in COL11A1 encoding collagen (1) XI (rs3753841; NM_080629.2_c.4004C>T; p.(Pro1335Leu); P=7.07e-11, OR=1.118). Using CRISPR mutagenesis we generated Pax1 knockout mice (Pax1-/-). In postnatal spines we found that PAX1 and collagen (1) XI protein both localize within the intervertebral disc (IVD)-vertebral junction region encompassing the growth plate, with less collagen (1) XI detected in Pax1-/- spines compared to wildtype. By genetic targeting we found that wildtype Col11a1 expression in costal chondrocytes suppresses expression of Pax1 and of Mmp3, encoding the matrix metalloproteinase 3 enzyme implicated in matrix remodeling. However, this suppression was abrogated in the presence of the AIS-associated COL11A1P1335L mutant. Further, we found that either knockdown of the estrogen receptor gene Esr2, or tamoxifen treatment, significantly altered Col11a1 and Mmp3 expression in chondrocytes. We propose a new molecular model of AIS pathogenesis wherein genetic variation and estrogen signaling increase disease susceptibility by altering a Pax1-Col11a1-Mmp3 signaling axis in spinal chondrocytes.

genetics↗

bioRxiv2021

p53 mutations exhibit sex specific gain-of-function activity in gliomagenesis

The tumor suppressor TP53 is the most frequently mutated gene in cancer. Most TP53 mutations are missense mutations in the DNA-binding domain, which in addition to loss of canonical p53 activity, frequently confer gain-of-function (GOF) aberrant transcriptional activity through mutant p53 localization to non-canonical genes. GOF phenotypes differ by mutation and cell identity and are reported to include increased proliferation, migration, metabolic reprogramming, and therapy resistance. We found that several recurring p53 mutations exhibit a sex-bias in patients with glioblastoma (GBM). In vitro and in vivo analysis of three mutations, p53R172H, p53Y202C, and p53Y217C revealed sex differences in each mutations ability to transform primary mouse astrocytes. p53R172H exhibited a far greater ability to transform female astrocytes than males, p53Y202C transformed both male and female astrocytes with a small male bias, and p53Y217C only exhibited GOF transformation effects in male astrocytes. These phenotypic differences reflect an interaction between sex and GOF mutation to drive unique gene expression patterns in cancer pathways. We found that mutant p53 exhibits sex and mutation specific aberrant genomic localization to the transcriptional start sites of upregulated genes, whose promoter regions were enriched for different sets of transcription factor DNA-binding motifs. Together, our data establish a novel paradigm for sex specific mutant p53 GOF activity in GBM with implications for all cancer.

cancer biology↗

bioRxiv2021

An in vivo approach to characterize novel variants associated with musculoskeletal disorders

Nemaline Myopathy (NM) is the most common congenital myopathy, characterized by extreme weakness of the respiratory, limb, and facial muscles. Pathogenic variants in Tropomyosin 2 (TPM2), which encodes a skeletal muscle specific actin binding protein essential for sarcomere function, cause a spectrum of musculoskeletal disorders that include NM as well as Cap Myopathy, congenital fiber type disproportion, and distal arthrogrypsosis (DA). TPM2-related disorders have not been modeled in vivo, so we expressed a series of dominant, pathogenic TPM2 variants in Drosophila embryos and found two variants, K49Del and E122K, significantly affected muscle morphogenesis and muscle function, in part by disrupting myotube guidance. Transient overexpression of K49Del and E122K also disrupted the morphogenesis of immortalized mouse myoblasts in vitro, and negatively affected zebrafish muscle development and function in vivo. We used our transient overexpression assays in zebrafish to characterize two novel TPM2 variants that we identified in DA patients (V129A and E139K), and found these variants caused musculoskeletal defects similar to those of the known pathogenic variants. In addition, the severity of musculoskeletal phenotypes in zebrafish expressing TPM2 variants correlated with the severity of clinical phenotypes observed in DA patients. Our study establishes transient overexpression in zebrafish as an efficient platform to characterize variants of uncertain significance in TPM2 in vivo, and suggests that this method can be used to predict the clinical severity of variants associated with DA and congenital myopathies.

genetics↗

bioRxiv2018

ATRAID, a genetic factor that regulates the clinical action of nitrogen-containing bisphosphonates on bone.

Nitrogen-containing bisphosphonates (N-BPs), such as alendronate, are the most widely prescribed medications for diseases involving bone, with nearly 200 million prescriptions written annually. Recently, widespread use of N-BPs has been challenged due to the risk of rare but traumatic side effects such as atypical femoral fracture (AFFs) and osteonecrosis of the jaw (ONJ). N-BPs bind to and inhibit farnesyl diphosphate synthase (FDPS), resulting in defects in protein prenylation. Yet it remains poorly understood what other cellular factors might allow N-BPs to exert their pharmacological effects. Here, we performed genome-wide studies in cells and patients to identify the poorly characterized gene, ATRAID. Loss of ATRAID function results in selective resistance to N-BP-mediated loss of cell viability and the prevention of alendronate-mediated inhibition of prenylation. ATRAID is required for alendronate inhibition of osteoclast function, and ATRAID-deficient mice have impaired therapeutic responses to alendronate in both postmenopausal and senile (old age) osteoporosis models. Lastly, we performed exome sequencing on patients taking N-BPs that suffered ONJ or an AFF. ATRAID is one of three genes that contain rare non-synonymous coding variants in patients with ONJ or AFF that is also differentially expressed in poor outcome groups of patients treated with N-BPs. We functionally validated this patient variation in ATRAID as conferring cellular hypersensitivity to N-BPs. Our work adds key insight into the mechanistic action of N-BPs and the processes that might underlie differential responsiveness to N-BPs in people. One Sentence SummaryATRAID is essential for responses to the commonly prescribed osteoporosis drugs nitrogen-containing bisphosphonates. OverlineBONE

genomics↗