Clusterin silencing restores myoblasts viability and down modulates the inflammatory process in osteoporotic disease

Abstract

Background Targeting new molecular pathways leading to Osteoporosis (OP) and Osteoarthritis (OA) is a hot topic for drug discovery. Clusterin (CLU) is a glycoprotein involved in inflammation, proliferation, cell death, neoplastic disease, Alzheimer disease and aging. The present study focuses on the expression and the role of CLU in influencing the decrease of muscle mass and fiber senescence in OP-OA condition. Methods Vastus lateralis muscle biopsies were collected from 20 women with OP undergoing surgery for fragility hip fracture and 20 women undergoing arthroplasty for hip osteoarthritis. Results We found an overexpression of CLU in degenerated fibers in OP closely correlated with interleukin 6 (IL6) and histone H4 acetylation level. Conversely, in OA muscle tissues we observed a weak expression of CLU but no nuclear histone H4 acetylation. Ex vivo studies on isolated human myoblasts confirmed CLU overexpression in OP as compared to OA (p < 0.001). CLU treatment of isolated OP and OA myoblasts showed: modulation of proliferation, morphological changes, increase of histone H4 acetylation and induction of myogenin (MYOG) activation in OP myoblast only. In OP condition, functional knockdown of CLU by siRNA restores proliferative myoblasts capability and tissue damage repair, carried out by an evident upregulation of Transglutaminase 2 (TGM2). We also observed downmodulation of CX3CR1 expression with consequent impairing of the inflammatory infiltrate recruitment. Conclusions Results obtained suggest a potential role of CLU in OP by influencing myoblasts terminal differentiation, epigenetic regulation of muscle cell differentiation and senescence. Moreover, CLU silencing points out its role in the modulation of tissue damage repair and inflammation, proposing it as a new diagnostic marker for muscle degeneration and a potential target for specific therapeutic intervention in OP related sarcopenia.

Integrated genomic and proteomic analyses identify stimulus-dependent molecular changes associated with distinct modes of skeletal muscle atrophy

“…For example, Pla2g7 mutations have been associated with a greater increase in lean muscle mass following training ( Wootton et al, 2007 ). Clu expression has also been linked with declining muscle mass in osteoporosis and found to negatively regulate muscle cell viability ( Pucci et al, 2019 ). Altogether, these integrated analyses provide robust protein biomarkers associated with atrophy (atroproteins), some of which could causally determine atrophy-associated changes of skeletal muscle in response to dexamethasone, cancer cachexia, and aging.…”

Clusterin negatively modulates mechanical stress-mediated ligamentum flavum hypertrophy through TGF-β1 signaling

“…The results showed significantly increased expression of CLU in LF samples; however, there was no marked difference in CLU levels in blood samples from the LFH group and non-LFH group. CLU upregulation has been reported in local tissue, such as OA-induced cartilage degeneration 38 , osteoporotic disease 39 , tears of dry eye 19 and brain tissues of AD patients. The results suggested specifically high expression of CLU in LF tissues prone to fibrosis.…”

Oligonucleotide Therapeutics for Age-Related Musculoskeletal Disorders: Successes and Challenges

“…Furthermore, ex vivo transfection of satellite cells from 3-month-old mice enhanced engraftment when these cells were transplanted into cardiotoxin-injured tibialis anterior muscle. In a different study, Pucci et al used siRNA to target clusterin, a glycoprotein involved in proliferation and cell death [ 74 ]. Ex vivo knock-down of clusterin restored proliferative capability and improved markers of tissue damage repair in human myoblasts from elderly patients with osteoporosis.…”