{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,7]],"date-time":"2026-08-07T17:01:36Z","timestamp":1786122096217,"version":"build-2736575974"},"reference-count":39,"publisher":"Portland Press Ltd.","issue":"8","license":[{"start":{"date-parts":[[2026,7,29]],"date-time":"2026-07-29T00:00:00Z","timestamp":1785283200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100012543","name":"Shanghai Science and Technology Development Foundation","doi-asserted-by":"publisher","award":["YDZX20223100001004"],"award-info":[{"award-number":["YDZX20223100001004"]}],"id":[{"id":"10.13039\/100012543","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["portlandpress.com"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2026,8,19]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>3\u03b2-Hydroxysteroid dehydrogenases (3\u03b2HSDs) are key enzymes in steroid metabolism, catalyzing C3 oxidation\u2013reduction and \u03945\u2192\u03944 isomerization reactions that govern metabolic flux across multiple steroidogenic pathways. However, the functional diversity of 3\u03b2HSDs involved in bufadienolide metabolism in amphibians remains poorly explored. Here, we systematically characterized the 3\u03b2HSD gene family in the Asian toad (Bufo bufo gargarizans) using integrated transcriptomic, biochemical, and metabolomic analyses. Seven Bg-3\u03b2HSD genes were identified from multi-tissue transcriptomes generated under control and Pb2+ exposure conditions, and six were heterologously expressed for functional evaluation. In vitro assays revealed pronounced functional divergence among Bg-3\u03b2HSD isoforms. Bg-3\u03b2HSD1 primarily catalyzed bidirectional C3 redox reactions of C21 steroids and bile acid-related substrates, consistent with canonical steroidogenic roles. In contrast, Bg-3\u03b2HSD2 enzyme exhibited broad substrate specificity and high catalytic efficiency toward hormones, bile acids, and bufadienolides. In addition to canonical C3 redox reactions and \u03945\u2192\u03944 isomerization, Bg-3\u03b2HSD2 also displayed additional oxidation activity at the C17 position for several steroid substrates. A third homolog, Bg-HSD3B7 (GenBank accession no. XM 044303756.1), selectively converted 7\u03b1-hydroxylated sterols, suggesting a potential role in classical bile acid metabolism. Integration of tissue-specific expression profiles with bufadienolide distribution patterns suggests that Bg-3\u03b2HSD2 may contribute to connecting classical steroid metabolism with bufadienolide biosynthesis in adrenal tissue. Together, the present study identifies Bg-3\u03b2HSD2 as an efficient and versatile steroid-transforming enzyme, expands our knowledge of functional diversity within the amphibian 3\u03b2HSD family, and provides insights into the enzymatic basis of steroid and bufadienolide metabolism in B. bufo gargarizans.<\/jats:p>","DOI":"10.1042\/bsr20260032","type":"journal-article","created":{"date-parts":[[2026,7,29]],"date-time":"2026-07-29T16:18:49Z","timestamp":1785341929000},"update-policy":"https:\/\/doi.org\/10.1042\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Functional characterization of 3\u03b2-hydroxysteroid dehydrogenases in Asiatic toad reveals an efficient broad substrate specificity of Bg-3\u03b2HSD2"],"prefix":"10.1042","volume":"46","author":[{"given":"Qian","family":"Meng","sequence":"first","affiliation":[{"name":"State Key Laboratory of Discovery and Utilization of Functional Components in Traditional Chinese Medicine, The SATCM Key Laboratory for New Resources & Quality Evaluation of Chinese Medicine, The MOE Key Laboratory for Standardization of Chinese Medicines and Shanghai Key Laboratory of Compound Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yaoting","family":"Hu","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Discovery and Utilization of Functional Components in Traditional Chinese Medicine, The SATCM Key Laboratory for New Resources & Quality Evaluation of Chinese Medicine, The MOE Key Laboratory for Standardization of Chinese Medicines and Shanghai Key Laboratory of Compound Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wenjie","family":"Chen","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Discovery and Utilization of Functional Components in Traditional Chinese Medicine, The SATCM Key Laboratory for New Resources & Quality Evaluation of Chinese Medicine, The MOE Key Laboratory for Standardization of Chinese Medicines and Shanghai Key Laboratory of Compound Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chuanguang","family":"Xiao","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Discovery and Utilization of Functional Components in Traditional Chinese Medicine, The SATCM Key Laboratory for New Resources & Quality Evaluation of Chinese Medicine, The MOE Key Laboratory for Standardization of Chinese Medicines and Shanghai Key Laboratory of Compound Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Li","family":"Yang","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Discovery and Utilization of Functional Components in Traditional Chinese Medicine, The SATCM Key Laboratory for New Resources & Quality Evaluation of Chinese Medicine, The MOE Key Laboratory for Standardization of Chinese Medicines and Shanghai Key Laboratory of Compound Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rufeng","family":"Wang","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Discovery and Utilization of Functional Components in Traditional Chinese Medicine, The SATCM Key Laboratory for New Resources & Quality Evaluation of Chinese Medicine, The MOE Key Laboratory for Standardization of Chinese Medicines and Shanghai Key Laboratory of Compound Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Beibei","family":"Zhang","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Discovery and Utilization of Functional Components in Traditional Chinese Medicine, The SATCM Key Laboratory for New Resources & Quality Evaluation of Chinese Medicine, The MOE Key Laboratory for Standardization of Chinese Medicines and Shanghai Key Laboratory of Compound Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2269-925X","authenticated-orcid":false,"given":"Shujuan","family":"Zhao","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Discovery and Utilization of Functional Components in Traditional Chinese Medicine, The SATCM Key Laboratory for New Resources & Quality Evaluation of Chinese Medicine, The MOE Key Laboratory for Standardization of Chinese Medicines and Shanghai Key Laboratory of Compound Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhengtao","family":"Wang","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Discovery and Utilization of Functional Components in Traditional Chinese Medicine, The SATCM Key Laboratory for New Resources & Quality Evaluation of Chinese Medicine, The MOE Key Laboratory for Standardization of Chinese Medicines and Shanghai Key Laboratory of Compound Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"288","published-online":{"date-parts":[[2026,8,7]]},"reference":[{"key":"2026080703511257600_B1","doi-asserted-by":"publisher","first-page":"525","DOI":"10.1210\/er.2002-0050","article-title":"Molecular biology of the 3\u03b2-hydroxysteroid dehydrogenase\/ \u03945-\u03944 isomerase gene family","volume":"26","author":"Simard","year":"2005","journal-title":"Endocr. 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