YKL-05-099 is a salt-inducible kinase (SIK) inhibitor. It can inhibit the activity of SIK1 (IC50: 10 nM) and SIK3 (IC50: 30 nM), and has a slightly weaker inhibitory effect on SIK2 (IC50: 40 nM). [1]

SIK3:30 nM, SIK2:40 nM, SIK1:10 nM

YKL-05-099 inhibits the production of the inflammatory cytokines TNFα, IL-6 and IL-12p40, and only modestly enhances IL-1β release in BMDCs stimulated with the yeast cell wall extract Zymosan A. YKL-05-099 has slightly less potent SIK2-inhibitory (IC50=40 nM) and IL-10-enhancing activities (EC50=460 nM). YKL-05-099 binds to SIK1 and SIK3 (IC50s: 10 and 30 nM, respectively, in a competitive binding assay). Preincubating bone marrow-derived macrophages with YKL-05-099 decreases LPS stimulated phosphorylation of HDAC5 at the SIK-specific phosphorylation site Ser259 [1].

METHODS: YKL-05-099 (6, 18 mg/kg/d) was tested in surgically ovariectomized mice by intraperitoneal injection to see if it could increase cancellous bone mass in hypogonadal female mice.
RESULTS YKL-05-099 treatment increased trabecular bone mass in the femur and L5 vertebrae of hypogonadal female mice, indicating that the agent does not cause significant defects in cortical bone mass. [1]