CLICK-enabled analogues reveal pregnenolone interactomes in cancer and immune cells

Neuroactive Steroids, Toll-like Receptors, and Neuroimmune Regulation: Insights into Their Impact on Neuropsychiatric Disorders

Pregnane neuroactive steroids, notably allopregnanolone and pregnenolone, exhibit efficacy in mitigating inflammatory signals triggered by toll-like receptor (TLR) activation, thus attenuating the production of inflammatory factors. Clinical studies highlight their therapeutic potential, particularly in conditions like postpartum depression (PPD), where the FDA-approved compound brexanolone, an intravenous formulation of allopregnanolone, effectively suppresses TLR-mediated inflammatory pathways, predicting symptom improvement. Additionally, pregnane neurosteroids exhibit trophic and anti-inflammatory properties, stimulating the production of vital trophic proteins and anti-inflammatory factors. Androstane neuroactive steroids, including estrogens and androgens, along with dehydroepiandrosterone (DHEA), display diverse effects on TLR expression and activation. Notably, androstenediol (ADIOL), an androstane neurosteroid, emerges as a potent anti-inflammatory agent, promising for therapeutic interventions. The dysregulation of immune responses via TLR signaling alongside reduced levels of endogenous neurosteroids significantly contributes to symptom severity across various neuropsychiatric disorders. Neuroactive steroids, such as allopregnanolone, demonstrate efficacy in alleviating symptoms of various neuropsychiatric disorders and modulating neuroimmune responses, offering potential intervention avenues. This review emphasizes the significant therapeutic potential of neuroactive steroids in modulating TLR signaling pathways, particularly in addressing inflammatory processes associated with neuropsychiatric disorders. It advances our understanding of the complex interplay between neuroactive steroids and immune responses, paving the way for personalized treatment strategies tailored to individual needs and providing insights for future research aimed at unraveling the intricacies of neuropsychiatric disorders.

De novo steroidogenesis in tumor cells drives bone metastasis and osteoclastogenesis

Osteoclasts play a central role in cancer-cell-induced osteolysis, but the molecular mechanisms of osteoclast activation during bone metastasis formation are incompletely understood. By performing RNA sequencing on a mouse breast carcinoma cell line with higher bone-metastatic potential, here we identify the enzyme CYP11A1 strongly upregulated in osteotropic tumor cells. Genetic deletion of Cyp11a1 in tumor cells leads to a decreased number of bone metastases but does not alter primary tumor growth and lung metastasis formation in mice. The product of CYP11A1 activity, pregnenolone, increases the number and function of mouse and human osteoclasts in vitro but does not alter osteoclast-specific gene expression. Instead, tumor-derived pregnenolone strongly enhances the fusion of pre-osteoclasts via prolyl 4-hydroxylase subunit beta (P4HB), identified as a potential interaction partner of pregnenolone. Taken together, our results demonstrate that Cyp11a1-expressing tumor cells produce pregnenolone, which is capable of promoting bone metastasis formation and osteoclast development via P4HB.

Pregnenolone sulfate induces transcriptional and immunoregulatory effects on T cells

Pregnenolone sulfate is a steroid metabolite of the steroidogenesis precursor, pregnenolone, with similar functional properties, including immunosuppression. We recently reported an elevation in serum levels of pregnenolone sulfate in children with malaria, contributing to an immunosuppressed state. Yet, the molecular mechanisms in which this steroid exerts its immunoregulatory functions are lacking. In this study, we examined the effects of pregnenolone sulfate on T cell viability, proliferation and transcriptome. We observed a pregnenolone sulfate dose-dependent induction of T cell death and reduction in proliferation. RNA sequencing analysis of pregnenolone sulfate-treated T cells for 2 and 24 h revealed the downregulation of pro-inflammatory genes and the upregulation of the steroid nuclear receptor superfamily, NR4A, as early-response genes. We also report a strong activation of the integrated stress response mediated by the upregulation of EIF2AK3. These results contribute to the knowledge on transcriptional regulation driving the immunoregulatory effects of pregnenolone sulfate on T cells.

Local Effects of Steroid Hormones within the Bone Microenvironment

Steroid hormone production via the adrenal cortex, gonads, and placenta (so-called glandular steroidogenesis) is responsible for the endocrine control of the body's homeostasis and is organized by a feedback regulatory mechanism based on the hypothalamus-pituitary-steroidogenic gland axis. On the other hand, recently discovered extraglandular steroidogenesis occurring locally in different tissues is instead linked to paracrine or autocrine signaling, and it is independent of the control by the hypothalamus and pituitary glands. Bone cells, such as bone-forming osteoblasts, osteoblast-derived osteocytes, and bone-resorbing osteoclasts, respond to steroid hormones produced by both glandular and extraglandular steroidogenesis. Recently, new techniques to identify steroid hormones, as well as synthetic steroids and steroidogenesis inhibitors, have been introduced, which greatly empowered steroid hormone research. Based on recent literature and new advances in the field, here we review the local role of steroid hormones in regulating bone homeostasis and skeletal lesion formation. The novel idea of extraglandular steroidogenesis occurring within the skeletal system raises the possibility of the development of new therapies for the treatment of bone diseases.

CLICK-chemoproteomics and molecular dynamics simulation reveals pregnenolone targets and their binding conformations in Th2 cells

Pregnenolone (P5) is synthesized as the first bioactive steroid in the mitochondria from cholesterol. Clusters of differentiation 4 (CD4+) and Clusters of differentiation 8 (CD8+) immune cells synthesize P5 de novo; P5, in turn, play important role in immune homeostasis and regulation. However, P5's biochemical mode of action in immune cells is still emerging. We envisage that revealing the complete spectrum of P5 target proteins in immune cells would have multifold applications, not only in basic understanding of steroids biochemistry in immune cells but also in developing new therapeutic applications. We employed a CLICK-enabled probe to capture P5-binding proteins in live T helper cell type 2 (Th2) cells. Subsequently, using high-throughput quantitative proteomics, we identified the P5 interactome in CD4+ Th2 cells. Our study revealed P5's mode of action in CD4+ immune cells. We identified novel proteins from mitochondrial and endoplasmic reticulum membranes to be the primary mediators of P5's biochemistry in CD4+ and to concur with our earlier finding in CD8+ immune cells. Applying advanced computational algorithms and molecular simulations, we were able to generate near-native maps of P5-protein key molecular interactions. We showed bonds and interactions between key amino acids and P5, which revealed the importance of ionic bond, hydrophobic interactions, and water channels. We point out that our results can lead to designing of novel molecular therapeutics strategies.