• Triggering receptor expressed on myeloid cells 2 (TREM2) is a transmembrane receptor belonging to the immunoglobulin superfamily, primarily expressed in microglia in the brain and macrophages in the periphery. TREM2 is involved in various biological functions, including cell maturation, cell proliferation, cell survival, phagocytosis, and the regulation of inflammation. It serves as a central immune signaling hub that is induced by pathological conditions and plays a critical role in neurodegenerative diseases such as Alzheimer's disease as well as in cancer.
• The hemizygous R47H variant of triggering receptor expressed on myeloid cells 2 (TREM2), a microglia-specific gene in the brain, increases risk for late-onset Alzheimer’s disease (AD).
• Gene editing strategy: The exons 1~5 of mouse Trem2 gene that encode the full-length protein were replaced by human TREM2 exons 1~5 with R47H mutation in B-hTREM2*R47H mice. The 3’UTR region of the mouse gene are replaced by human counterparts. The chimeric TREM2 expression is driven by endogenous mouse Trem2 promoter, while mouse Trem2 gene transcription and translation will be disrupted.
• mRNA expression analysis: Mouse Trem2 mRNA was only detectable in wild-type C57BL/6JNifdc mice. Human TREM2 mRNA was detectable in homozygous B-Htrem2*R47H mice but not in wild-type mice. Sequence analysis showed that the homozygous B-hTREM2*R47H mice consists of a G to A point mutation at amino acid 47.
• Protein expression analysis: Human TREM2 was detectable in spleen, hippocampus, cortex and cerebellum of homozygous B-hTREM2*R47H mice, but not in wild-type mice.
• Application:  This product is used for pharmacodynamics and safety evaluation of Alzheimer's disease (AD).

Gene targeting strategy for B-hTREM2*R47H mice. The exons 1~5 of mouse Trem2 gene that encode the full-length protein were replaced by human TREM2 exons 1~5 with R47H mutation in B-hTREM2*R47H mice. The 3’UTR region of the mouse gene are replaced by human counterparts. The chimeric TREM2 expression is driven by endogenous mouse Trem2 promoter, while mouse Trem2 gene transcription and translation will be disrupted.

Strain specific analysis of TREM2 mRNA expression in wild-type C57BL/6 mice and B-hTREM2*R47H mice by RT-PCR. Cortex RNA were isolated from wild-type C57BL/6 mice (+/+) and homozygous B-hTREM2*R47H mice (H/H), then cDNA libraries were synthesized by reverse transcription, followed by PCR with mouse or human TREM2 primers. Mouse Trem2 mRNA was detectable only in wild-type C57BL/6 mice. Human TREM2 mRNA was detectable only in homozygous B-hTREM2*R47H mice but not in wild-type mice, and R47H mutation were confirmed via Sanger Sequencing.

Western blot analysis of TREM2 protein expression in homozygous B-hTREM2*R47H mice. Various tissue lysates were collected from wild-type C57BL/6 mice (+/+) and homozygous B-hTREM2*R47H mice (H/H), and then analyzed by western blot with species-specific anti-TREM2 antibody (CST, 91068S). 50 μg total proteins were loaded for western blotting analysis. hTREM2 was detected in spleen, cortex, hippocampus and cerebellum from homozygous B-hTREM2*R47H mice, but not in wild-type mice.