Identification of novel OCRL isoforms associated with phenotypic differences between Dent disease-2 and Lowe syndrome. Issue 2 (29th September 2021)

• Record Type: Journal Article
• Authors: Sakakibara, Nana; Ijuin, Takeshi; Horinouchi, Tomoko; Yamamura, Tomohiko; Nagano, China; Okada, Eri; Ishiko, Shinya; Aoto, Yuya; Rossanti, Rini; Ninchoji, Takeshi; Awano, Hiroyuki; Nagase, Hiroaki; Minamikawa, Shogo; Tanaka, Ryojiro; Matsuyama, Takeshi; Nagatani, Koji; Kamei, Koichi; Jinnouchi, Kumiko; Ohtsuka, Yasufumi; Oka, Masafumi; Araki, Yoshinori; Tanaka, Toju; Harada, Mari S; Igarashi, Toru; Kitahara, Hikaru; Morisada, Naoya; Nakamura, Shun-ichi; Okada, Taro; Iijima, Kazumoto; Nozu, Kandai
• Is Part Of: Nephrology dialysis transplantation. Volume 37:Issue 2(2022)
• Page Start: 262
• Page End: 270
• Publication Date: 2021-09-29
• Subjects: Dent disease-2 -- Lowe syndrome, OCRL -- PI(4, 5)P2 5-phosphatase; Nephrology -- Periodicals; Hemodialysis -- Periodicals; Kidneys -- Transplantation -- Periodicals; Hemodialysis; Kidneys -- Transplantation; Nephrology; Periodicals; 616.61
• DOI: 10.1093/ndt/gfab274
• Languages: English
• ISSNs: 0931-0509

Abstract

ABSTRACT: Background: Although Lowe syndrome and Dent disease-2 are caused by Oculocerebrorenal syndrome of Lowe ( OCRL ) mutations, their clinical severities differ substantially and their molecular mechanisms remain unclear. Truncating mutations in OCRL exons 1–7 lead to Dent disease-2, whereas those in exons 8–24 lead to Lowe syndrome. Herein we identified the mechanism underlying the action of novel OCRL protein isoforms. Methods: Messenger RNA samples extracted from cultured urine-derived cells from a healthy control and a Dent disease-2 patient were examined to detect the 5′ end of the OCRL isoform. For protein expression and functional analysis, vectors containing the full-length OCRL transcripts, the isoform transcripts and transcripts with truncating mutations detected in Lowe syndrome and Dent disease-2 patients were transfected into HeLa cells. Results: We successfully cloned the novel isoform transcripts from OCRL exons 6–24, including the translation-initiation codons present in exon 8. In vitro protein-expression analysis detected proteins of two different sizes (105 and 80 kDa) translated from full-length OCRL, whereas only one protein (80 kDa) was found from the isoform and Dent disease-2 variants. No protein expression was observed for the Lowe syndrome variants. The isoform enzyme activity was equivalent to that of full-length OCRL; the Dent disease-2 variants retained >50% enzyme activity, whereas the Lowe syndrome variants retained <20% activity. Conclusions: We elucidated the molecular mechanism underlying the two different phenotypes in OCRL -related diseases; the functional OCRL isoform translated starting at exon 8 was associated with this mechanism.