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Mamm Genome. 2016 Feb;27(1-2):29-46. doi: 10.1007/s00335-015-9614-7. Epub 2015 Dec 11.

The GPSM2/LGN GoLoco motifs are essential for hearing.

Author information

1
Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 6997801, Israel.
2
Department of Biological Sciences, Bethlehem University, Bethlehem, Palestine.
3
Department of Biochemistry and Molecular Biology, Weiss Faculty of Life Sciences, Tel Aviv University, 69978, Tel Aviv, Israel.
4
Department of Biology, Technion-Israel Institute of Technology, 32000, Haifa, Israel.
5
Department of Cell Biology, Emory University, Atlanta, GA, 30322, USA.
6
Laboratory of Cell Asymmetry, Center for Developmental Biology, Riken, Kobe, 650-0047, Japan.
7
Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 6997801, Israel. karena@post.tau.ac.il.

Abstract

The planar cell polarity (PCP) pathway is responsible for polarizing and orienting cochlear hair cells during development through movement of a primary cilium, the kinocilium. GPSM2/LGN, a mitotic spindle-orienting protein associated with deafness in humans, is a PCP effector involved in kinocilium migration. Here, we link human and mouse truncating mutations in the GPSM2/LGN gene, both leading to hearing loss. The human variant, p.(Trp326*), was identified by targeted genomic enrichment of genes associated with deafness, followed by massively parallel sequencing. Lgn (ΔC) mice, with a targeted deletion truncating the C-terminal GoLoco motifs, are profoundly deaf and show misorientation of the hair bundle and severe malformations in stereocilia shape that deteriorates over time. Full-length protein levels are greatly reduced in mutant mice, with upregulated mRNA levels. The truncated Lgn (ΔC) allele is translated in vitro, suggesting that mutant mice may have partially functioning Lgn. Gαi and aPKC, known to function in the same pathway as Lgn, are dependent on Lgn for proper localization. The polarization of core PCP proteins is not affected in Lgn mutants; however, Lgn and Gαi are misoriented in a PCP mutant, supporting the role of Lgn as a PCP effector. The kinocilium, previously shown to be dependent on Lgn for robust localization, is essential for proper localization of Lgn, as well as Gαi and aPKC, suggesting that cilium function plays a role in positioning of apical proteins. Taken together, our data provide a mechanism for the loss of hearing found in human patients with GPSM2/LGN variants.

PMID:
26662512
PMCID:
PMC5913375
DOI:
10.1007/s00335-015-9614-7
[Indexed for MEDLINE]
Free PMC Article

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