Cullin-associated NEDD8-dissociated protein 1, a novel interactor of rabphilin-3A, deubiquitylates rabphilin-3A and regulates arginine vasopressin secretion in PC12 cells.

Abstract

The molecular mechanism involved in the exocytosis of arginine vasopressin (AVP) is not fully known. Rabphilin-3A has been suggested as a novel autoantigen in infundibulo-neurohypophysitis (LINH), which leads to central diabetes insipidus through insufficient secretion of AVP. However, the role of rabphilin-3A in the pathogenesis of LINH remains unclear. Thus, the aim of the present study was to identify proteins binding rabphilin-3A in the posterior pituitary. Using glutathione S-transferase (GST)-pulldown assays and proteomic analyses, cullin-associated NEDD8-dissociated protein 1 (CAND1) was identified as a rabphilin-3A-binding protein in the posterior pituitary. Co-immunoprecipitation assays indicated that CAND1 interacted endogenously with rabphilin-3A. In addition, immunohistochemistry experiments showed that CAND1 immunoreactivity was detected mainly in the posterior pituitary, intermediate lobe, and the supraoptic nucleus in the hypothalamus, and less in the anterior lobe, partially co-localizing with rabphilin-3A. Overexpression of CAND1 resulted in deubiquitylation of rabphilin-3A in PC12 cells. Moreover, overexpression of CAND1 in PC12 cells co-transfected with AVP enhanced both basal and KCl-stimulated AVP secretion. The findings indicate that CAND1 inhibits the ubiquitylation of rabphilin-3A and positively regulates AVP secretion. These data shed light on a novel potential mechanism involving rabphilin-3A in AVP secretion, and suggest a new role of CAND1 as a regulator of hormone or neurotransmitter secretion.

• Authors: Kohtaro Nakashima, Seiji Takeuchi, Shintaro Iwama, Atsushi Kiyota, Yoshinori Yasuda, Naoko Iwata, Atsushi Enomoto, Hiroshi Arima, Yoshihisa Sugimura
• Journal: Endocrine journal (Endocr J) Vol. 65 Issue 3 Pg. 325-334 (Mar 28 2018) ISSN: 1348-4540 [Electronic] Japan
• PMID: 29367474 (Publication Type: Journal Article)

Chemical References

• Adaptor Proteins, Signal Transducing
• Nerve Tissue Proteins
• Transcription Factors
• Vesicular Transport Proteins
• Arginine Vasopressin
• Deubiquitinating Enzymes

Topics

• Adaptor Proteins, Signal Transducing (metabolism)
• Animals
• Arginine Vasopressin (metabolism)
• Deubiquitinating Enzymes (genetics, metabolism)
• Nerve Tissue Proteins (metabolism)
• PC12 Cells
• Pituitary Gland, Posterior (metabolism)
• Rats
• Rats, Sprague-Dawley
• Transcription Factors (genetics, metabolism)
• Vesicular Transport Proteins (metabolism)
• Rabphilin-3A