TRPM4:

• Gene Information: Human TRPM4 (Transient Receptor Potential Melastatin 4) is located on chromosome 19, and encodes a calcium-activated non-selective monovalent cation channel.
• Protein Expression: TRPM4 exhibits broad tissue distribution, with expression detected in the central nervous system, muscles, prostate, colon, small intestine, lung and liver.
• Signaling Pathway: TRPM4 executes biological functions mainly by regulating monovalent cation influx to alter cellular membrane potential, thereby regulating diverse downstream signaling cascades. For instance, it modulates the duration of action potentials in cardiomyocytes and drives epithelial-mesenchymal transition within the tumor microenvironment.
• Therapeutic Application: TRPM4 is a promising therapeutic target for numerous diseases such as cardiac arrhythmia, ischemic stroke and multiple malignancies. Small-molecule TRPM4 channel inhibitors and antibody-based therapeutics are currently under evaluation in preclinical and clinical studies.

TRPM4

• Part of exons 17-20 of mouse Trpm4 gene that encode transmembrane domain, extracellular domain and part of cytoplasmic region is replaced by human counterparts in B-hTRPM4 mice. The genomic region of mouse Trpm4 gene that encodes N- and C- terminal cytoplasmic portion is retained. The promoter, 5’UTR and 3’UTR of the mouse gene are also retained. The chimeric TRPM4 expression is driven by endogenous mouse Trpm4 promoter, while mouse Trpm4 gene transcription and translation will be disrupted.

• Human TRPM4 mRNA was exclusively detectable in homozygous B-hTRPM4 mice but not in wild-type mice.

Analysis of TRPM4 mRNA expression in wild-type C57BL/6N mice and homozygous B-hTRPM4 mice by RT-PCR. Brain RNA were isolated from wild-type C57BL/6N mice (+/+) and homozygous B-hTRPM4 mice (H/H), then cDNA libraries were synthesized by reverse transcription, followed by PCR with mouse or human TRPM4 primers. Mouse Trpm4 mRNA was only detectable in wild-type C57BL/6N mice. Human TRPM4 mRNA was exclusively detectable in homozygous B-hTRPM4 mice but not in wild-type mice.

• TRPM4 was detectable in brain, heart (low expression), lung, liver, large intestine and stomach, as the antibody used cross-reacted with both human and mouse TRPM4 protein.

Western blot analysis of TRPM4 protein expression in wild-type C57BL/6N mice and homozygous B-hTRPM4 mice. Various tissue lysates were collected from wild-type C57BL/6N mice (+/+) and homozygous B-hTRPM4 mice (H/H), and then analyzed by western blot with anti-TRPM4 antibody (Abcam, ab106200). 40 μg total proteins were loaded for western blot analysis. TRPM4 was detectable in brain, heart (low expression), lung, liver, large intestine and stomach, as the antibody used cross-reacted with both human and mouse TRPM4 protein.