title: Age-related changes in expression of CTL2/SLC44A2 and its isoforms in the mouse inner ear.
abstract: The membrane glycoprotein CTL2/SLC44A2 is expressed by supporting cells in the inner ear and has been identified as a target of antibodies that may induce auto-immune hearing loss. To determine if CTL2/SLC44A2 also has roles in inner ear development and to distinguish between isoform-specific roles, we assessed age-related changes in expression of CTL2/SLC44A2 isoforms and protein in the developing murine inner ear. We determined that both isoform p1 and isoform p2 (named for the upstream p1 and proximal p2 promoters that control alternate exons 1a and 1b) were robustly expressed as early as E14 and persisted during embryonic development, but after birth the p1 isoform fell to barely detectable levels while isoform p2 levels were maintained. This trend continued and became even more apparent later in post-natal development and remained in mature ears until at least 6 weeks of age. In aged (18 mo old) mice, the level of isoform p1 transcripts rose again to levels similar to the p2 isoform like that seen early in development. At the earliest stage examined, CTL2/SLC44A2 protein was expressed in both immature supporting cells and immature sensory cells, but after birth expression in the sensory cells declined in both the utricle and cochlea and by day P1 expression of CTL2/SLC44A2 was restricted to supporting cells. The changes we observed in isoform distribution are indicative of differential developmental roles and age related changes between the two isoforms of CTL2/SLC44A2 in the inner ear.
authors: Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI 48109, USA.
authors: Lisa A
authors: LA
authors: Beyer
authors: Maria M
authors: MM
authors: Galano
authors: Thankam S
authors: TS
authors: Nair
authors: Pavan K
authors: PK
authors: Kommareddi
authors: Su-Hua
authors: SH
authors: Sha
authors: Yehoash
authors: Y
authors: Raphael
authors: Thomas E
authors: TE
authors: Carey
mesh_terms: D000367:Age Factors; D000375:Aging / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D007758:Ear, Inner / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D007150:Immunohistochemistry; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008808:Mice, Inbred CBA; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D026901:Membrane Transport Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; C571060:SLC44A2 protein, mouse