Tisp40, a spermatid specific bZip transcription factor, functions by binding to the unfolded protein response element via the Rip pathway

• Published in: Genes to cells : devoted to molecular & cellular mechanisms Vol. 10; no. 6; pp. 575 - 594
• Main Authors: Nagamori, Ippei, Yabuta, Norikazu, Fujii, Takayuki, Tanaka, Hiromitsu, Yomogida, Kentaro, Nishimune, Yoshitake, Nojima, Hiroshi
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.06.2005
• Subjects: Amino Acid Sequence; Animals; Base Sequence; Binding Sites - drug effects; Cell Line; Cell Nucleus - metabolism; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Electrophoretic Mobility Shift Assay; Endoplasmic Reticulum - metabolism; Gene Expression Regulation - drug effects; Glycoside Hydrolases - pharmacology; Glycosylation; HeLa Cells; Histidine - chemistry; Humans; Kidney - cytology; Kidney - embryology; Leucine Zippers; Luciferases - metabolism; Male; Mice; Molecular Sequence Data; Phosphorylation; Phylogeny; Protein Binding - drug effects; Protein Processing, Post-Translational; Protein Structure, Tertiary; Proteins - metabolism; Receptor-Interacting Protein Serine-Threonine Kinases; Response Elements - genetics; RNA, Messenger - metabolism; Sequence Deletion; Spermatids - metabolism; Spermatogenesis; Transcription Factors - chemistry; Transcription Factors - genetics; Transcription Factors - metabolism
• ISSN: 1356-9597; 1365-2443
• DOI: 10.1111/j.1365-2443.2005.00860.x

TISP40, a mouse spermatid‐specific gene, encodes a CREB/CREM family transcription factor that is predominantly expressed during spermiogenesis. We report here that TISP40 generates two types of proteins, Tisp40α and Tisp40β, both of which contain a transmembrane domain and localize to the endoplasmic reticulum (ER). In contrast, mutant proteins lacking the transmembrane domain (Tisp40α/βΔTM) primarily localize to the nucleus. Endoglycosidase H treatment shows that the C‐terminus of Tisp40α/β is glycosylated. Protease experiments demonstrate that Tisp40α/β are Type II transmembrane proteins that are released into the nucleus by a two‐step cleavage mechanism called ‘regulated intramembrane proteolysis’ (Rip). Unlike previously published observations, Tisp40α does not bind to the NF‐κB site; instead, it specifically binds to the unfolded protein response element (UPRE). Luciferase assays reveal that Tisp40βΔTM activates transcription through UPRE. Northern blot analysis shows that Tisp40α/βΔTM proteins up‐regulate EDEM (ER degradation of enhancing α‐manosidase‐like protein) mRNA. These observations unveil a novel event in mouse spermiogenesis and show that the final stage of trans‐criptional regulation is controlled by the Rip pathway.