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CDK5 regulatory subunit-associated protein 1-like 1 (CDKAL1) is a tail-anchored protein in the endoplasmic reticulum (ER) of insulinoma cells.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 2012 Dec 07; Vol. 287 (50), pp. 41808-19. Date of Electronic Publication: 2012 Oct 09. - Publication Year :
- 2012
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Abstract
- Genome-wide association studies have led to the identification of numerous susceptibility genes for type 2 diabetes. Among them is Cdkal1, which is associated with reduced β-cell function and insulin release. Recently, CDKAL1 has been shown to be a methylthiotransferase that modifies tRNA(Lys) to enhance translational fidelity of transcripts, including the one encoding proinsulin. Here, we report that out of several CDKAL1 isoforms deposited in public databases, only isoform 1, which migrates as a 61-kDa protein by SDS-PAGE, is expressed in human islets and pancreatic insulinoma INS-1 and MIN6 cells. We show that CDKAL1 is a novel member of the tail-anchored protein family and exploits the TCR40/Get3-assisted pathway for insertion of its C-terminal transmembrane domain into the endoplasmic reticulum. Using endo-β-N-acetylglucosaminidase H and peptide:N-glycosidase F sensitivity assays on CDKAL1 constructs carrying an N-glycosylation site within the luminal domain, we further established that CDKAL1 is an endoplasmic reticulum-resident protein. Moreover, we observed that silencing CDKAL1 in INS-1 cells reduces the expression of secretory granule proteins prochromogranin A and proICA512/ICA512-TMF, in addition to proinsulin and insulin. This correlated with reduced glucose-stimulated insulin secretion. Taken together, our findings provide new insight into the role of CDKAL1 in insulin-producing cells and help to understand its involvement in the pathogenesis of diabetes.
- Subjects :
- Animals
Base Sequence
Cell Line, Tumor
Cyclin-Dependent Kinase 5 genetics
Diabetes Mellitus genetics
Diabetes Mellitus metabolism
Diabetes Mellitus pathology
Endoplasmic Reticulum genetics
Endoplasmic Reticulum pathology
Gene Silencing
Humans
Insulinoma genetics
Insulinoma pathology
Molecular Sequence Data
Neoplasm Proteins genetics
Proinsulin genetics
Proinsulin metabolism
Protein Isoforms genetics
Protein Isoforms metabolism
Protein Structure, Tertiary
Rats
Receptor-Like Protein Tyrosine Phosphatases, Class 8 genetics
Receptor-Like Protein Tyrosine Phosphatases, Class 8 metabolism
tRNA Methyltransferases
Cyclin-Dependent Kinase 5 metabolism
Endoplasmic Reticulum metabolism
Insulinoma metabolism
Neoplasm Proteins metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1083-351X
- Volume :
- 287
- Issue :
- 50
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 23048041
- Full Text :
- https://doi.org/10.1074/jbc.M112.376558