Poster abstracts
Poster number 11 submitted by Bennett Yunker
Sub-sarcomeric level 3D spatial multiomics reveals distinct spatial organization of ECC transcripts on ribosomes
Bennett Yunker (Biophysics Graduate Program), Vladimir Bogdanov (Biophysics Graduate Program), Yiran Guo (Physiology and Cellular Biology), Galina Sakuna
Abstract:
Localized protein synthesis of excitationcontraction coupling (ECC) proteins is emerging as a key determinant of cardiomyocyte organization, yet remains poorly defined in cardiac biology. To address this gap, we developed a three-dimensional multiplex imaging platform that maps multiple mRNA species relative to structural landmarks in single cardiomyocytes, enabling quantitative subsarcomeric analysis of cardiac mRNA organization.
Single-cell analysis revealed three spatially distinct modes of transcript partitioning within the subsarcomeric compartment. Ryr2 and Jph2 transcripts were enriched in a Z-lineproximal domain within ~200 nm of -actinin, consistent with junctional SRassociated release domains. Myh6, Tnnc1, and Camk2d transcripts occupied a neighboring interZ-line region (~200400 nm from -actinin), whereas Atp2a2/SERCA2a transcripts were broadly distributed across ribosome-enriched regions. Thus, ECC-related transcripts are not uniformly dispersed, but instead partition into transcript-specific subsarcomeric territories. DBSCAN-based clustering analysis further revealed structured local inter-transcript organization. Low-abundance transcripts, including Camk2d, Cacna1c, and Atp1a1, were preferentially positioned near other mRNAs, with ~70% of puncta located within 150 nm of another transcript. In parallel, Myh6 and Atp2a2 emerged as recurrent core components of mRNA clusters, each present in ~75% of clusters, significantly exceeding random expectation.
Together, these results define a transcript-specific spatial architecture of ECC mRNAs within cardiomyocytes and support a model in which protein synthesis is organized within discrete, subsarcomeric domains. This organization defines an additional layer of spatial control over protein expression that may contribute to the assembly and maintenance of cardiac functional modules.
Keywords: Excitation Contraction Coupling, Transcription, Nanoscale Organization