biostudies-literatureJatzlau JJoan Oró FI fellowshipAgència de Gestió d'Ajuts Universitaris i de RecercaDeutsche ForschungsgemeinschaftEuropean Union&apos;s Horizon 2020Marie Skłodowska-Curie H2020 COFUND ActionsAgència de Gestió d&apos;Ajuts Universitaris i de RecercaEinstein Stiftung BerlinMorbus Osler Society, GermanyFreie Universität BerlinEuropean Union's Horizon 202079https://www.ebi.ac.uk/biostudies/studies/S-EPMC11907993biostudies-literatureUnknown23(1)<h4>Background</h4>Receptor-activated SMADs trimerize with SMAD4 to regulate context-dependent target gene expression. However, the presence of a single SMAD1/5/8 binding motif in cis-regulatory elements alone does not trigger transcription in native contexts. We hypothesize that binding to composite motifs in which at least two SMAD binding sites are in close proximity would be enough to induce transcription as this scenario allows the simultaneous interaction of at least two SMAD proteins, thereby increasing specificity and affinity.<h4>Results</h4>Using more than 65 distinct firefly luciferase constructs, we delineated the minimal requirements for BMP-induced gene activation. We propose a model in which two SMAD-MH1 domains bind a SMAD-composite motif in a back-to-back fashion with a 5-BMC biologyRare but specific: 5-bp composite motifs define SMAD binding in BMP signaling.PMC11907993ECRTMO-KnausSGR 866-2021IRB_DREAM PhD 2022SFB 1444Do SNMees RAJatzlau JMartin-Malpartida PMacias MJKhan RJKnaus PMaas LMendez PLRuiz LfalseRare but specific: 5-bp composite motifs define SMAD binding in BMP signaling.<h4>Background</h4>Receptor-activated SMADs trimerize with SMAD4 to regulate context-dependent target gene expression. However, the presence of a single SMAD1/5/8 binding motif in cis-regulatory elements alone does not trigger transcription in native contexts. We hypothesize that binding to composite motifs in which at least two SMAD binding sites are in close proximity would be enough to induce transcription as this scenario allows the simultaneous interaction of at least two SMAD proteins, thereby increasing specificity and affinity.<h4>Results</h4>Using more than 65 distinct firefly luciferase constructs, we delineated the minimal requirements for BMP-induced gene activation. We propose a model in which two SMAD-MH1 domains bind a SMAD-composite motif in a back-to-back fashion with a 5-2025-01-01T00:00:00Z2025 Mar2026-06-01T06:05:33.56Z2025-04-03T23:26:23.975ZS-EPMC119079934008296410.1186/s12915-025-02183-1