Browsing by Subject "PLS3"

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  • Mäkitie, Riikka E.; Kämpe, Anders; Costantini, Alice; Alm, Jessica J.; Magnusson, Per; Mäkitie, Outi (2020)
    Recent advancements in genetic research have uncovered new forms of monogenic osteoporosis, expanding our understanding of the molecular pathways regulating bone health. Despite active research, knowledge on the pathomechanisms, disease-specific biomarkers, and optimal treatment in these disorders is still limited. Mutations in WNT1, encoding a WNT/beta-catenin pathway ligand WNT1, and PLS3, encoding X chromosomally inherited plastin 3 (PLS3), both result in early-onset osteoporosis with prevalent fractures and disrupted bone metabolism. However, despite marked skeletal pathology, conventional bone markers are usually normal in both diseases. Our study aimed to identify novel bone markers in PLS3 and WNT1 osteoporosis that could offer diagnostic potential and shed light on the mechanisms behind these skeletal pathologies. We measured several parameters of bone metabolism, including serum dickkopf-1 (DKK1), sclerostin, and intact and C-terminal fibroblast growth factor 23 (FGF23) concentrations in 17 WNT1 and 14 PLS3 mutation-positive subjects. Findings were compared with 34 healthy mutation-negative subjects from the same families. Results confirmed normal concentrations of conventional metabolic bone markers in both groups. DKK1 concentrations were significantly elevated in PLS3 mutation-positive subjects compared with WNT1 mutation-positive subjects (p <.001) or the mutation-negative subjects (p = .002). Similar differences were not seen in WNT1 subjects. Sclerostin concentrations did not differ between any groups. Both intact and C-terminal FGF23 were significantly elevated in WNT1 mutation-positive subjects (p = .039 and p = .027, respectively) and normal in PLS3 subjects. Our results indicate a link between PLS3 and DKK1 and WNT1 and FGF23 in bone metabolism. The normal sclerostin and DKK1 levels in patients with impaired WNT signaling suggest another parallel regulatory mechanism. These findings provide novel information on the molecular networks in bone. Extended studies are needed to investigate whether these biomarkers offer diagnostic value or potential as treatment targets in osteoporosis. (c) 2020 American Society for Bone and Mineral Research.
  • Mäkitie, Riikka E.; Costantini, Alice; Kämpe, Anders; Alm, Jessica J.; Mäkitie, Outi (2019)
    Osteoporosis, characterized by deteriorated bone microarchitecture and low bone mineral density, is a chronic skeletal disease with high worldwide prevalence. Osteoporosis related to aging is the most common form and causes significant morbidity and mortality. Rare, monogenic forms of osteoporosis have their onset usually in childhood or young adulthood and have specific phenotypic features and clinical course depending on the underlying cause. The most common form is osteogenesis imperfecta linked to mutations in COL1A1 and COL1A2, the two genes encoding type I¬ collagen. However, in the past years, remarkable advancements in bone research have expanded our understanding of the intricacies behind bone metabolism and identified novel molecular mechanisms contributing to skeletal health and disease. Especially high-throughput sequencing techniques have made family-based studies an efficient way to identify single genes causative of rare monogenic forms of osteoporosis and these have yielded several novel genes that encode proteins partaking in type I collagen modification or regulating bone cell function directly. New forms of monogenic osteoporosis, such as autosomal dominant osteoporosis caused by WNT1 mutations or X-linked osteoporosis due to PLS3 mutations, have revealed previously unidentified bone-regulating proteins and clarified specific roles of bone cells, expanded our understanding of possible inheritance mechanisms and paces of disease progression, and highlighted the potential of monogenic bone diseases to extend beyond the skeletal tissue. The novel gene discoveries have introduced new challenges to the classification and diagnosis of monogenic osteoporosis, but also provided promising new molecular targets for development of pharmacotherapies. In this article we give an overview of the recent discoveries in the area of monogenic forms of osteoporosis, describing the key cellular mechanisms leading to skeletal fragility, the major recent research findings and the essential challenges and avenues in future diagnostics and treatments.
  • Makitie, Riikka E.; Niinimäki, Tuukka; Suo-Palosaari, Maria; Kampe, Anders; Costantini, Alice; Toiviainen-Salo, Sanna; Niinimäki, Jaakko; Mäkitie, Outi (2020)
    Objective:Mutations in the X-chromosomalPLS3-gene, encoding Plastin 3, lead to severe early-onset osteoporosis, suggesting a major role for PLS3 in bone metabolism. However, the consequences of abnormal PLS3 function in bone and other tissues remain incompletely characterized. This study evaluated spinal consequences of aberrant PLS3 function in patients withPLS3mutations. Design:A cross-sectional cohort study with spinal magnetic resonance imaging of 15PLS3mutation-positive (age range 9-77 years) and 13 mutation-negative (9-70 years) subjects. Images were reviewed for spinal alignment, vertebral heights and morphology, intervertebral disc changes and possible endplate deterioration. Results:Vertebral changes were significantly more prevalent in the mutation-positive subjects compared with the mutation-negative subjects; they were most abundant in upper thoracic spine, and in all age groups and both sexes, although more prominent in males. Difference in anterior vertebral height reduction was most significant in T5 and T6 (p= 0.046 andp= 0.041, respectively). Mid-vertebral height reduction was most significant in T3 and T5 (p= 0.037 andp= 0.005, respectively), and, for male mutation-positive subjects only, in T4 and T6-10 (p= 0.005-0.030 for each vertebra). Most of the abnormal vertebrae were biconcave in shape but thoracic kyphosis or lumbar lordosis were unchanged. Vertebral endplates were well-preserved in the mutation-positive subjects with even fewer Schmorl nodes than the mutation-negative subjects (10 vs. 16). Conclusions:Compromised PLS3 function introduces severe and progressive changes to spinal structures that are present already in childhood, in both sexes and most abundant in upper thoracic spine. Cartilaginous structures are well-preserved.
  • Makitie, Riikka E.; Kampe, Anders J.; Taylan, Fulya; Makitie, Outi (2017)
    Purpose of Review This review summarizes our current knowledge on primary osteoporosis in children with focus on recent genetic findings. Recent Findings Advances in genetic research, particularly next-generation sequencing, have found several genetic loci that associate with monogenic forms of inherited osteoporosis, widening the scope of primary osteoporosis beyond classical osteogenesis imperfecta. New forms of primary osteoporosis, such as those related to WNT1, PLS3, and XYLT2, have identified defects outside the extracellular matrix components and collagen-related pathways, in intracellular cascades directly affecting bone cell function. Summary Primary osteoporosis can lead to severe skeletal morbidity, including abnormal longitudinal growth, compromised bone mass gain, and noticeable fracture tendency beginning at childhood. Early diagnosis and timely care are warranted to ensure the best achievable bone health. Future research will most likely broaden the spectrum of primary osteoporosis, hopefully provide more insight into the genetics governing bone health, and offer new targets for treatment.