Expression of the Transmembrane Lysosomal Protein SCARB2/Limp-2 in Renin Secretory Granules Controls Renin Release

Abstract

Background/Aims: Renin processing and storage is believed to occur in lysosome-like structures in the afferent arteriole. SCARB2/Limp-2 is a transmembrane lysosomal protein responsible for the intracellular trafficking of β-glucocerebrosidase. This study aimed to confirm the expression of SCARB2/Limp-2 in renin secretory granules, and explore its role in renin processing and secretion. Methods: Co-localisation studies of (pro)renin with lysosomal membrane proteins, SCARB2/Limp-2, LAMP-1 and LAMP-2, were performed in mouse and human kidney sections. Intrarenal expression and secretion of (pro)renin in wild-type (WT) and Limp-2^-/- mice were compared with and without stimulation. Results: SCARB2/Limp-2, LAMP-1 and LAMP-2 co-localised with (pro)- renin in mouse and human kidney. Plasma renin concentration was increased in Limp-2^-/- mice when compared to WT littermates. No change in (pro)renin expression, however, was observed in Limp-2^-/- mouse kidney cortex by immunofluorescence microscopy, Western blotting, quantitative RT-PCR or the ultrastructural appearance of renin secretory granules. Acute stimulation of renin release by isoprenaline or hydralazine was similar in WT and Limp-2^-/- mice. Following chronic salt restriction, however, immunofluorescence microscopy showed less (pro)renin expressed in Limp-2^-/- compared with WT mouse kidneys, and there was significantly less prorenin but not renin by Western blotting in Limp-2^-/- mouse kidney cortex, despite no difference in circulating renin levels. Conclusion: Renin secretory granules possess integral lysosomal proteins, confirming that they are indeed modified lysosomes. Limp-2 deficiency leads to a minor increase in circulating renin. Limp-2, however, is not required for acute or chronic stimulation of renin release.

Early Prediction of Tacrolimus-Induced Tubular Toxicity in Pediatric Refractory Nephrotic Syndrome Using Machine Learning

“…Studies have shown that the lack of SCARB2, which may be related to glomerulosclerosis (Berkovic et al, 2008), can also lead to proteolysis failure resulting in tubular proteinuria (Desmond et al, 2011). Additionally, acute arteriopathy is one of the manifestations of acute CNI-induced nephrotoxicity (Naesens et al, 2009), which may be caused by the activation of the RAS system (Hocherl et al, 2004;Ruster and Wolf, 2006;Lee et al, 2012). The deficiency of LIMP-2 may indirectly activate the RAS system by increasing the level of renin which is an important upstream substance in the RAS system (Lee et al, 2012).…”

“…Additionally, acute arteriopathy is one of the manifestations of acute CNI-induced nephrotoxicity (Naesens et al, 2009), which may be caused by the activation of the RAS system (Hocherl et al, 2004;Ruster and Wolf, 2006;Lee et al, 2012). The deficiency of LIMP-2 may indirectly activate the RAS system by increasing the level of renin which is an important upstream substance in the RAS system (Lee et al, 2012). Therefore, the LIMP-2 may be correlated to the TACinduced nephrotoxicity.…”

Absence of the lysosomal protein Limp‐2 attenuates renal injury in crescentic glomerulonephritis

“…All animals used were males aged between 10 and 14 weeks on a mixed 129Sv/Bl6 background. The initial description of urinary obstruction in Limp‐2 −/− mice, however, was not observed in animals on the current genetic background used in the present study and was rarely seen in our previous studies 5 , 29 , 30 . Genotyping was determined with the help of polymerase chain reaction using genomic DNA isolated from a short piece of tail taken at 2–4 weeks of age.…”

“…The initial description of urinary obstruction in Limp-2 À/ À mice, however, was not observed in animals on the current genetic background used in the present study and was rarely seen in our previous studies. 5,29,30 Genotyping was determined with the help of polymerase chain reaction using genomic DNA isolated from a short piece of tail taken at 2-4 weeks of age. Nonaccelerated experimental anti-GBM disease was induced in WT and Limp-2 À/ À littermates by intraperitoneal injections of 2 mg of anti-GBM nephrotoxic sheep serum (a generous gift from A/Professor Peter Tipping, Monash University, Australia) per gram of mouse body weight, as described previously.…”

Plasticity of renal endocrine function

“…These vesicles belong to the family of lysosome-related organelles (LRO) (177). As lysosomes, they have an acidic content (137), and they contain proteins, such as lysosomal integral membrane protein 2 (LIMP-2), lysosomal-associated membrane protein 1 (LAMP-1), and LAMP-2 (98,152), which are important for directing proteins to lysosomes (148). At the level of the Golgi apparatus, glycosylated prorenin is sorted to these lysosome-related organelles.…”