FIND ARTICLE

Volume: 
Issue: 
3
Date of issue: 

Osteoporosis is a chronic systemic disease characterized by progressive loss of bone mass and microarchitectural deterioration of bone tissue. Bone lesions are caused by different factors, including hereditary ones. A process named bone remodeling is the effect of balanced osteoclastogenesis and oste- oblastogenesis, two primary processes controlled by a number of proteins. The osteoclasts proliferation and differentiation are regulated by: PU.1, MITF, M-CSF, c-Src, PI-3K, c-Fms, RANK, NFATc1, NFκB and cFos/Fra-1 proteins. Activation of bone resorption during remodeling depends on the direct interac- tion of osteoblasts and osteoclasts. Osteoblast cell surface protein RANK interacts with its ligand RANKL – the cytokine secreted by osteoblasts. Despite that, Wnt signalling pathway proteins and their coreceptors – LRP-5 and LRP-6 proteins, are involved in regulation of osteoblast function. Over 3 decades passed since identification of genes/alleles responsible for osteoporosis phenotype. The most intensively studied genes up to now are VDR, COLIA1 and ER. Genes involved were invented as four groups of biological factors: cytokines, growth factors, bone matrix proteins and calciotropic hormones and receptors. Type I collagen is a fibrillar protein, the main constituent of bone matrix, VDR is cytopla- smic vitamin D receptor as well as ER, estrogen receptor, which regulates expression of target genes involved in bone homeostasis. The correlation between particular LRP-5 alleles and function of transmem- brane LRP-5 protein is not clear, however it is suggested that polymorphisms of LRP-5 gene may contribute to BMD alterations, thus influencing the risk of developing osteoporosis. Besides allelic variants of TGF β -1 gene, a number of mutations of proinflammatory cytokines IL-1 and IL-6 genes exist, of which translation products correlates with the level of estrogens in women which in turn may influence osteoporotic pathophysiology. Among sequence alterations analised are polymorphic restriction sites BsmI, ApaI, EcoRV, FokI and TaqI of VDR gene and their association with femoral-neck and total skeleton BMD. Researchers are particularly interested in polymorphism at Sp1 binding site in COLIA1 gene, which is suggested to be a genetic marker of microarchitectural bone deterioration. Moreover, there are a number of polymorphisms associated with osteoporotic phenotype i.e. BstI, PvuII i XbaI in ER α gene, PvuII in CD38 gene as well as others in OSCAR and RUNX2 genes. Despite a huge number of data on genetic background of osteoporosis, there are still many discrepancies. However genetic research on osteoporosis will surely lead to unequivocal identification of molecular markers which could be finally useful for diagnostic and therapeutic purposes.

Author of the article: 

The Editorial Board
Andrzej Łukaszyk - przewodniczący, Zofia Bielańska-Osuchowska, Szczepan Biliński, Mieczysław Chorąży, Aleksander Koj, Włodzimierz Korochoda, Leszek Kuźnicki, Aleksandra Stojałowska, Lech Wojtczak

Editorial address:
Katedra i Zakład Histologii i Embriologii Uniwersytetu Medycznego w Poznaniu, ul. Święcickiego 6, 60-781 Poznań, tel. +48 61 8546453, fax. +48 61 8546440, email: mnowicki@ump.edu.pl

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