{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T05:02:34Z","timestamp":1790053354820,"version":"4.0.1"},"reference-count":47,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T00:00:00Z","timestamp":1789603200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Natural Science Foundation of Jilin Province","award":["20220101342JC"],"award-info":[{"award-number":["20220101342JC"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Animals"],"abstract":"<jats:p>(1) Background: Seasonal breeding constraints represent a long-standing barrier to efficient sheep production worldwide. Small Tail Han sheep, a Chinese indigenous breed that exhibits year-round estrus independent of photoperiod, offers a unique natural model for investigating the regulatory mechanisms underlying estrus cyclicity\u2014yet the molecular basis of this remarkable trait remains largely unexplored. This study therefore aimed to compare ovarian whole-transcriptome profiles between Small Tail Han sheep (year-round estrus) and Ujumqin sheep (seasonal estrus) during estrus and diestrus. Specifically, we sought to characterize breed-specific transcriptional response strategies, identify key miRNAs associated with continuous estrus, and construct ceRNA networks that mediate ovarian estrous cycle regulation. (2) Methods: To address these objectives, we profiled ovarian transcriptomes of Small Tail Han sheep (year-round estrus) and Ujumqin sheep (seasonal estrus) during both estrus and diestrus (12 samples total) using whole-transcriptome sequencing, systematically characterizing the expression landscapes of mRNAs, miRNAs, lncRNAs and circRNAs. Through differential expression analysis, GO\/KEGG functional enrichment, multi-tiered miRNA screening, and ceRNA network construction, we compared the transcriptional response strategies between the two breeds. (3) Results: Our findings revealed two unexpected and divergent patterns. Small Tail Han sheep showed 1881 differentially expressed mRNAs between estrus and diestrus, 82-fold more than the 23 in Ujumqin sheep, suggesting a broader mRNA-level transcriptional response in the year-round estrus breed. circRNAs were predominantly up-regulated (80\u201385%) in both breeds, while mRNAs and lncRNAs were predominantly down-regulated, uncovering a conserved \u201ccircRNA-up, mRNA-down\u201d regulatory logic across breeds. Multi-tiered screening identified 38 \u201cbrake-releaser\u201d miRNAs (high in diestrus, down-regulated in estrus) and 21 \u201caccelerator\u201d miRNAs (low in diestrus, up-regulated in estrus), which together constitute a \u201cde-repression\u2013activation\u201d dual regulatory mode. ceRNA network analysis further revealed a clear functional stratification: conserved core miRNAs targeted \u201csensor\u201d pathways (cAMP, PI3K-Akt, MAPK), whereas accelerator miRNAs specifically targeted \u201cexecutor\u201d pathways (estrogen signaling, progesterone-mediated oocyte maturation, Hippo signaling). Network topology analysis pinpointed miR-199a-5p, miR-204-3p and miR-199b as the core hubs bridging the two regulatory modules. (4) Conclusions: Taken together, our findings redefine the molecular basis of year-round estrus\u2014moving beyond single-gene mutations or overexpression to an enhanced global transcriptomic responsiveness of the ovary. This work provides a fresh conceptual framework for understanding the divergence of reproductive strategies in sheep and offers actionable candidate targets for genetic improvement of continuous estrus traits.<\/jats:p>","DOI":"10.3390\/ani16182925","type":"journal-article","created":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T11:05:53Z","timestamp":1789988753000},"page":"2925","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Whole-Transcriptome Landscape Deciphers a ceRNA-Mediated \u201cDe-Repression\u2013Activation\u201d Circuit Governing Continuous Estrus in Ovine"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4281-1621","authenticated-orcid":false,"given":"Bo","family":"Gu","sequence":"first","affiliation":[{"name":"College of Life Science, Jilin Normal University, Siping 136000, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"}]},{"given":"Jiayao","family":"Cui","sequence":"additional","affiliation":[{"name":"College of Life Science, Jilin Normal University, Siping 136000, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"validation","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"}]},{"given":"Ruchao","family":"Tian","sequence":"additional","affiliation":[{"name":"College of Life Science, Jilin Normal University, Siping 136000, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"validation","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"}]},{"given":"Limin","family":"Sun","sequence":"additional","affiliation":[{"name":"Jilin Academy of Agricultural Sciences (Northeast Agricultural Research Center of China), Changchun 136100, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"software","vocabulary":"credit"},{"role":"resources","vocabulary":"credit"},{"role":"funding-acquisition","vocabulary":"credit"}]},{"given":"Mingxuan","family":"Sui","sequence":"additional","affiliation":[{"name":"College of Plant Protection, Jilin Agricultural University, Changchun 130118, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"software","vocabulary":"credit"},{"role":"resources","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0009-0005-1647-0095","authenticated-orcid":false,"given":"Xiaowei","family":"Wei","sequence":"additional","affiliation":[{"name":"College of Life Science, Jilin Normal University, Siping 136000, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"investigation","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"}]},{"given":"Huaizhi","family":"Jiang","sequence":"additional","affiliation":[{"name":"College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"},{"role":"funding-acquisition","vocabulary":"credit"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"La, Y., He, X., Zhang, L., Di, R., Wang, X., Gan, S., Zhang, X., Zhang, J., Hu, W., and Chu, M. 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