Abstract
TRPML3, a member of the transient receptor potential (TRP) family, is an inwardly rectifying, non-selective Ca2+-permeable cation channel that is regulated by extracytosolic Na+ and H+ and can be activated by a variety of small molecules. The severe auditory and vestibular phenotype of the TRPML3(A419P) varitint-waddler mutation made this protein particularly interesting for inner ear biology. To elucidate the physiological role of murine TRPML3, we conditionally inactivated Trpml3 in mice. Surprisingly, lack of functional TRPML3 did not lead to circling behavior, balance impairment or hearing loss.
Highlights
The mammalian TRPML gene family consists of TRPML1, TRPML2, and TRPML3
Subcellular localization studies of heterologously expressed TRPML channels revealed that TRPML1 and TRPML2 are expressed in late endosomes and lysosomes, whereas TRPML3 presumably shuttles between multiple intracellular compartments and the plasma membrane [14]
Generation of a floxed Trpml3 allele (Trpml3lox) transient receptor potential (TRP) channel knockouts have successfully been generated through targeted deletion of a genomic region encoding the presumptive pore-loop domain of the ion channel [18,19,20]
Summary
The mammalian TRPML gene family consists of TRPML1, TRPML2, and TRPML3. Mutations in human TRPML1 cause the lysosomal storage disease Mucolipidosis Type IV [1,2,3]. We generated a targeting vector that, after homologous recombination, resulted in a modified Trpml3 allele carrying two loxP sites flanking exon 11 (Fig. 1B). RT-PCR amplification of specific cDNA sequences before and after the site of deletion indicated that wild-type and Trpml3 D mRNA was expressed in kidney and the inner ear of all animals (Fig. 2D,E; RT-2 and 3).
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