Cell Type–Specific Targeting of Different Smooth Muscle Cell Populations by Intersectional Genetics

BACKGROUND: The Cre/loxP recombination system is the main tool for cell type-specific lineage tracing and gene targeting. Currently available smooth muscle cell (SMC)-specific Cre mouse lines show off-target activity outside the SMC lineage and are unable to distinguish among arterial SMCs (ASMCs), venous SMCs, and nonvascular SMCs (NVSMCs). These limitations prevent ASMC- and NVSMC-specific gene targeting, which is required to characterize the role of SMCs in different organs and diseases. METHODS: was used. Disease-specific transcriptional changes of pulmonary ASMCs and NVSMCs were determined in the Sugen 5416/hypoxia model of pulmonary arterial hypertension. Usefulness for functional studies was assessed by inactivation of the genes for the splicing factors RBPMS (RNA-binding protein with multiple splicing) and RBPMS2 (RNA-binding protein with multiple splicing 2) in ASMCs. RESULTS: in ASMCs increased thickness of the muscular layer in pulmonary arteries, whereas inactivation in all SMCs abolished the contractile phenotype of NVSMCs in the intestine. CONCLUSIONS: The successful generation of mouse lines specifically targeting different subtypes of SMCs enhances specificity, allowing distinction between vascular and nonvascular effects of diseased SMCs. The identification of vessel bed-specific gene signatures will pave the way for specific manipulation of SMCs in distinct diseased organs, such as the lung in pulmonary arterial hypertension.