Targeting cathepsin S promotes activation of OLF1-BDNF/TrkB axis to enhance cognitive function.

BACKGROUND: Cathepsin S (CTSS) is a cysteine protease that played diverse roles in immunity, tumor metastasis, aging and other pathological alterations. At the cellular level, increased CTSS levels have been associated with the secretion of pro-inflammatory cytokines and disrupted the homeostasis of Ca2+ flux. Once CTSS was suppressed, elevated levels of anti-inflammatory cytokines and changes of Ca2+ influx were observed. These findings have inspired us to explore the potential role of CTSS on cognitive functions. METHODS: We conducted classic Y-maze and Barnes Maze tests to assess the spatial and working memory of Ctss-/- mice, Ctss+/+ mice and Ctss+/+ mice injected with the CTSS inhibitor (RJW-58). Ex vivo analyses including long-term potentiation (LTP), Golgi staining, immunofluorescence staining of sectioned whole brain tissues obtained from experimental animals were conducted. Furthermore, molecular studies were carried out using cultured HT-22 cell line and primary cortical neurons that treated with RJW-58 to comprehensively assess the gene and protein expressions. RESULTS: Our findings reported that targeting cathepsin S (CTSS) yields improvements in cognitive function, enhancing both working and spatial memory in behavior models. Ex vivo studies showed elevated levels of long-term potentiation levels and increased synaptic complexity. Microarray analysis demonstrated that brain-derived neurotrophic factor (BDNF) was upregulated when CTSS was knocked down by using siRNA. Moreover, the pharmacological blockade of the CTSS enzymatic activity promoted BDNF expression in a dose- and time-dependent manner. Notably, the inhibition of CTSS was associated with increased neurogenesis in the murine dentate gyrus. These results suggested a promising role of CTSS modulation in cognitive enhancement and neurogenesis. CONCLUSION: Our findings suggest a critical role of CTSS in the regulation of cognitive function by modulating the Ca2+ influx, leading to enhanced activation of the BDNF/TrkB axis. Our study may provide a novel strategy for improving cognitive function by targeting CTSS.

Targeting lysosomal cysteine protease cathepsin S reveals immunomodulatory therapeutic strategy for oxaliplatin-induced peripheral neuropathy.

Rationale: Oxaliplatin-induced peripheral neuropathy (OIPN) is a common adverse effect that causes delayed treatment and poor prognosis among colorectal cancer (CRC) patients. However, its mechanism remains elusive, and no effective treatment is available. Methods: We employed a prospective cohort study of adult patients with pathologically confirmed stage III CRC receiving adjuvant chemotherapy with an oxaliplatin-based regimen for investigating OIPN. To further validate the clinical manifestations and identify a potential therapeutic strategy, animal models, and in vitro studies on the mechanism of OIPN were applied. Results: Our work found that (1) consistent with clinical findings, OIPN was observed in animal models. Targeting the enzymatic activity of cathepsin S (CTSS) by pharmacological blockade and gene deficiency strategy alleviates the manifestations of OIPN. (2) Oxaliplatin treatment increases CTSS expression by enhancing cytosol translocation of interferon response factor 1 (IRF1), which then facilitates STIM-dependent store-operated Ca2+ entry homeostasis. (3) The cytokine array demonstrated an increase in anti-inflammatory cytokines and suppression of proinflammatory cytokines in mice treated with RJW-58. (4) Mechanistically, inhibiting CTSS facilitated olfactory receptors transcription factor 1 release from P300/CBP binding, which enhanced binding to the interleukin-10 (IL-10) promoter region, driving IL-10 downstream signaling pathway. (5) Serum CTSS expression is increased in CRC patients with oxaliplatin-induced neurotoxicity. Conclusions: We highlighted the critical role of CTSS in OIPN, which provides a therapeutic strategy for the common adverse side effects of oxaliplatin.

Biochemical characterization of an acid phosphatase from Thermus thermophilus.

A recombinant putative acid phosphatase from Thermus thermophilus was expressed and purified from Escherichia coli. The recombinant phosphatase displayed activities in a broad range of temperature, from 40 to 90 degrees C, with optimal temperature at 70 degrees C. In addition, the recombinant enzyme had activities in a wide range of pH, from 3.6 to 9.1, with optimal pH at 6 in acetate buffer and with optimal pH at 6.5 in Hepes buffer. Furthermore, it showed significant thermal stability and still possessed 44% residual activity after 70 degrees C treatment for 15 min. Moreover, the recombinant phosphatase showed broad substrates specificities for monophosphate esters, p-nitrophenyl phosphate (pNPP) being the most preferred substrate, and it was able to resist inhibition by sodium tartrate. Additionally, the recombinant protein formed stable oligomer under partially denatured conditions and required calcium ions for enzymic activity.