• ACVR2A encodes a receptor that mediates the functions of activins, which are members of the transforming growth factor-beta (TGF-beta) superfamily involved in diverse biological processes. The encoded protein is a transmembrane serine-threonine kinase receptor that mediates signaling by forming heterodimeric complexes with various combinations of type I and type II receptors and ligands in a cell-specific manner. The encoded type II receptor is primarily involved in ligand-binding and includes an extracellular ligand-binding domain, a transmembrane domain and a cytoplasmic serine-threonine kinase domain. 
• Gene editing strategy: The exons 1-11 of the mouse Acvr2a gene that encode the whole molecule, including promoter, 5’UTR, and part 3’UTR, were replaced by the exons 1-11 of the human counterparts, including human promoter, 5’UTR, and human 3’UTR in B-hACVR2A mice. The human ACVR2A expression is driven by the human ACVR2B promoter, while the mouse Acvr2a gene transcription and translation will be disrupted.
• mRNA Expression Analysis: Mouse Acvr2a mRNA was detectable in wild-type C57BL/6JNifdc mice and heterozygous B-hACVR2A mice. Human ACVR2A mRNA was detectable only in heterozygous B-hACVR2A mice but not in wild-type mice.

Gene editing strategy for B-hACVR2A mice. The exons 1-11 of the mouse Acvr2a gene that encode the whole molecule, including promoter, 5’UTR, and part 3’UTR, were replaced by the exons 1-11 of the human counterparts, including human promoter, 5’UTR, and human 3’UTR in B-hACVR2A mice. The human ACVR2A expression is driven by the human ACVR2B promoter, while the mouse Acvr2a gene transcription and translation will be disrupted.

Species specific analysis of ACVR2A mRNA expression in wild-type C57BL/6JNifdc mice and heterozygous humanized B-hACVR2A mice by RT-PCR. Gastrocnemius were collected from wild-type C57BL/6JNifdc mice (+/+) and heterozygous B-hACVR2A mice (H/+), then cDNA libraries were synthesized by reverse transcription, followed by PCR with mouse or human ACVR2A primers. Human ACVR2A mRNA was detectable only in heterozygous B-hACVR2A mice, but not in wild-type C57BL/6JNifdc mice. Human sequences were confirmed via Sanger Sequencing.

Species specific analysis of ACVR2A mRNA expression in wild-type C57BL/6JNifdc mice and heterozygous humanized B-hACVR2A mice by RT-qPCR. Gastrocnemius, inguinal fat, and brown fat were collected from wild-type C57BL/6JNifdc mice (+/+) and heterozygous B-hACVR2A mice (H/+) (n=1, 6-week-old, male), then cDNA libraries were synthesized by reverse transcription, followed by RT-qPCR with mouse or human ACVR2A primers. Human ACVR2A mRNA was detectable only in heterozygous B-hACVR2A mice, but not in wild-type C57BL/6JNifdc mice. Values are expressed as mean ± SEM.