Journal: Nutrients

Article Title: Sericin’s Potential in Osteoporosis Management: The Roles of L-Serine and D-Serine in Bone Metabolism Regulation

doi: 10.3390/nu17030574

Figure Lengend Snippet: The effect of D-serine administration on osteoclast activation in RAW264.7 cells. ( a ) Treatment with RANKL + M-CSF (R+M) significantly increased the expression of the osteoclast activation marker cathepsin K. Pretreatment with D-serine (50 μM) inhibited R+M-induced osteoclast activation. ( b ) From the results of panel B, compared to the untreated control and D-serine pretreatment groups, the R+M group exhibited significantly higher cathepsin K expression levels (* p < 0.05, ** p < 0.001). ( c ) Results from the TRAP assay indicated that D-serine pretreatment suppressed osteoclast activation (Scale bar: 200 µm). ( d , e ) A concentration-dependent effect of D-serine on cathepsin K expression was observed, with higher concentrations of D-serine resulting in greater inhibition. Compared to the untreated control, R+M, 10 μM D-serine, and 50 μM D-serine treatments significantly increased cathepsin K expression levels (* p < 0.05, ** p < 0.001). However, relative to the R+M group, 50 μM and 100 μM D-serine treatments significantly reduced cathepsin K expression levels (# p < 0.05, ### p < 0.001). Error bars represent the mean ± standard deviation. ( f ) Similar trends were observed in the TRAP activity assay, further confirming the dose-dependent inhibitory effect of D-serine on osteoclast activation (Scale bar: 200 µm).

Article Snippet: To prevent differentiation into osteoclasts, RAW264.7 cells were pretreated with 175 μM D-serine in DMEM for 24 h. For osteoclast differentiation, cells were treated with 50 ng/mL recombinant human-soluble RANK Ligand (RANKL; Oriental Yeast, Tokyo, Japan) and 20 ng/mL recombinant mouse macrophage colony-stimulating factor (M-CSF; R&D Systems, Minneapolis, MN, USA) in α-MEM medium containing 1% P/S for 5 days, with the induction medium being replaced every 2 days.

Techniques: Activation Assay, Expressing, Marker, Control, TRAP Assay, Concentration Assay, Inhibition, Standard Deviation, Activity Assay

Journal: Nutrients

Article Title: Sericin’s Potential in Osteoporosis Management: The Roles of L-Serine and D-Serine in Bone Metabolism Regulation

doi: 10.3390/nu17030574

Figure Lengend Snippet: Effects of sericin treatment on serum protein expression. IP-HPLC analysis of serum from the sericin-treated groups showed an increased expression of serine racemase and osteogenic proteins, including BMP2, osterix, Runx2, OPG, osteopontin, osteocalcin, and osteonectin, while reducing anti-osteogenic proteins like BMP3, PTH/PTHrP-R, and SOSTDC1. Osteoclastogenesis was inhibited by downregulating RANKL and HSP90. Inflammation and stromal fibrosis were reduced via downregulation of TNFα, NFATc1, TLR2, TLR3, and TGFβ1. These findings highlight sericin’s dual-action effects on bone metabolism and inflammation, supporting its therapeutic potential for osteoporosis.

Article Snippet: To prevent differentiation into osteoclasts, RAW264.7 cells were pretreated with 175 μM D-serine in DMEM for 24 h. For osteoclast differentiation, cells were treated with 50 ng/mL recombinant human-soluble RANK Ligand (RANKL; Oriental Yeast, Tokyo, Japan) and 20 ng/mL recombinant mouse macrophage colony-stimulating factor (M-CSF; R&D Systems, Minneapolis, MN, USA) in α-MEM medium containing 1% P/S for 5 days, with the induction medium being replaced every 2 days.

Techniques: Expressing