Involvement of -LRB- pro -RRB- renin receptor in the glomerular filtration barrier -LRB- Pro -RRB- renin receptor-bound prorenin not only causes the generation of angiotensin II via the nonproteolytic activation of prorenin , it also activates the receptor 's own intracellular signaling pathways independent of the generated angiotensin II . Within the kidneys , the -LRB- pro -RRB- renin receptor is not only present in the glomerular mesangium , it is also abundant in podocytes , which play an important role in the maintenance of the glomerular filtration barrier . Recent in vivo studies have demonstrated that the overexpression of the -LRB- pro -RRB- renin receptor to a degree similar to that observed in hypertensive rat kidneys leads to slowly progressive nephropathy with proteinuria . In addition , the handle region peptide , which acts as a decoy peptide and competitively inhibits the binding of prorenin to the receptor , is more beneficial than an angiotensin-converting enzyme inhibitor with regard to alleviating proteinuria and glomerulosclerosis in experimental animal models of diabetes and essential hypertension . Thus , the -LRB- pro -RRB- renin receptor may be upregulated in podocytes under hypertensive conditions and may contribute to the breakdown of the glomerular filtration barrier . Introduction When the -LRB- pro -RRB- renin receptor binds to the `` handle '' region of inactive prorenin , the receptor-bound prorenin gains its enzyme activity -LRB- ability to generate angiotensin I -RRB- without the proteolytic cleavage of the prosegment of prorenin in COS-7 cells -LSB- 1 , 2 -RSB- , presumably as a result of a conformational change . On the other hand , receptor-bound prorenin also triggers its own intracellular signaling pathways independent of the generated angiotensin II . Studies have shown that the stimulation of the -LRB- pro -RRB- renin receptor by renin/prorenin activates tyrosine phosphorylation leading to the activation of extracellular signal-related protein kinases -LRB- ERK -RRB- -LSB- 3 -RSB- and upregulates transforming growth factor-β1 -LRB- TGF-β1 -RRB- and matrix proteins without involving angiotensin II generation in human and rat mesangial cells -LSB- 4 -RSB- . In this review , we focus on the latest progress in elucidating the localization , regulation , and pathophysiological roles of the -LRB- pro -RRB- renin receptor in the kidneys . Localization in the kidney Studies have demonstrated that the -LRB- pro -RRB- renin receptor protein and messenger ribonucleic acid -LRB- mRNA -RRB- are expressed in the mesangium cells of human kidneys -LSB- 3 , 4 -RSB- . However , double immunohistochemical analyses using a polyclonal antirat -LRB- pro -RRB- renin receptor antibody demonstrated that the -LRB- pro -RRB- renin receptor was colocalized with a podocyte marker , podocalyxin , but not with a mesangium marker , Thy1 .1 , in rat kidneys -LSB- 5 -RSB- and electron microscopic analyses appeared to indicate the predominant presence of the rat -LRB- pro -RRB- renin receptor in podocytes , excluding the foot processes , and its absence in mesangial cells -LSB- 5 -RSB- . In addition , we recently detected -LRB- pro -RRB- renin receptor mRNA in cultured human podocytes -LRB- unpublished data -RRB- . Within the glomerulus , podocytes play an important role in the maintenance of the glomerular filtration barrier and podocyte injury leads to proteinuria and initiates glomerulosclerosis resulting in the progressive loss of renal function -LSB- 6 -RSB- . Therefore , -LRB- pro -RRB- renin receptor in the podocytes may contribute to proteinuria and renal injury through an angiotensin-II-dependent pathway , an angiotensin-II-independent pathway , or both pathways in chronic kidney diseases . Possible upregulation of -LRB- pro -RRB- renin receptor expression under hypertensive conditions In the kidneys of young hypertensive stroke-prone spontaneously hypertensive rats -LRB- SHRsp -RRB- , an increase by two - or threefold in the mRNA expression of the -LRB- pro -RRB- renin receptor has been observed -LSB- 7 -RSB- . However , the kidneys of older hypertensive SHRsp did not show an elevation in -LRB- pro -RRB- renin receptor mRNA expression . Because the binding of renin to the -LRB- pro -RRB- renin receptor lowers the -LRB- pro -RRB- renin receptor mRNA level through a promyelocytic zinc-finger-protein-mediated negative feedback mechanism -LSB- 8 -RSB- , a further increase in the plasma renin levels in old hypertensive SHRsp might inhibit the increase in -LRB- pro -RRB- renin receptor mRNA levels through a negative feedback loop . More recently , enhanced mRNA expression of the -LRB- pro -RRB- renin receptor was also observed in the clipped kidneys of Goldblatt hypertensive rats -LSB- 9 -RSB- . These results seem to provide evidence of the importance of hypertensive conditions in the regulation of -LRB- pro -RRB- renin receptor expression in the kidneys . Effects of -LRB- pro -RRB- renin receptor overexpression on the kidney Recent studies in transgenic rats overexpressing the human -LRB- pro -RRB- renin receptor gene nonspecifically by three to seven times demonstrated that glomerulosclerosis with proteinuria developed at 5 -- 6 months of age even in the absence of an elevation in blood pressure -LSB- 10 -RSB- . In the kidneys of 5 - to 6-month-old transgenic rats , mitogen-activated protein kinase -LRB- s -RRB- -LRB- MAPK -LRB- s -RRB- -RRB- were activated without recognizable tyrosine phosphorylation of the epidermal growth factor receptor and the expression of TGF-β1 was enhanced . The in vivo administration of angiotensin-converting enzyme -LRB- ACE -RRB- inhibitor did not inhibit the development of glomerulosclerosis , proteinuria , MAPK activation , or TGF-β1 expression in the kidneys despite a significant decrease in the renal angiotensin II level . As shown in Fig. 1 , recombinant rat prorenin stimulated MAPK activation in human-receptor-expressed cultured cells but human receptor was unable to evoke the enzyme activity of rat prorenin . Thus , the overexpression of the human -LRB- pro -RRB- renin receptor elicits slowly progressive nephropathy via angiotensin-II-independent MAPK activation but not through the stimulation of angiotensin II generation . However , hypertension developed at 7 months of age in transgenic rats overexpressing the human -LRB- pro -RRB- renin receptor gene exclusively in smooth muscle cells -LSB- 11 -RSB- . Because young transgenic rats of this strain show an enhanced expression of macula densa cyclooxygenase-2 that suppresses the tubuloglomerular feedback system and contributes to the inhibition of hypertension development -LSB- 12 -RSB- , hypertension may not yet have developed at 6 months of age or earlier . Therefore , we can interpret these observations as indicating that the hypertension may have occurred as a result of the nephropathy . However , further studies are needed to elucidate the involvement of the -LRB- pro -RRB- renin receptor in the development of hypertension . Fig. 1Both rat and human prorenin stimulate human -LRB- pro -RRB- renin receptor -LRB- h -LRB- P -RRB- RR -RRB- - dependent intracellular signals , but the h -LRB- P -RRB- RR activates human prorenin but does not activate rat prorenin Receptor-bound prorenin in diabetic kidneys Recombinant prorenin binds to recombinant -LRB- pro -RRB- renin receptor expressed compulsorily on the cell surfaces of COS-7 cells and prorenin bound to the receptor on the cell surfaces exerts renin activity without undergoing any change in its molecular weight . However , synthetic peptides containing the amino acid sequence corresponding to the `` handle '' region of the prorenin prosegment competitively inhibit prorenin from binding to cell membrane receptors -LSB- 13 -RSB- . In the absence of experimental data showing the blockade of renin signaling by the handle region peptide , we believe that the possible inhibition of receptor signals and angiotensin II generation by the handle region peptide should be interpreted as indicating the blockade of prorenin binding . Diabetic animals or patients have lower renin levels and higher prorenin levels than normal healthy controls -LSB- 14 , 15 -RSB- . The handle region peptide was administered to rats with streptozotosin-induced type I diabetes and the tissue angiotensin I and II levels in their kidneys , and the development of nephropathy were followed -LSB- 16 -RSB- . The administration of the handle region peptide for 6 months significantly inhibited the increase in renal angiotensin II levels and the development of proteinuria and glomerulosclerosis , suggesting that the nonproteolytic activation of prorenin bound to the -LRB- pro -RRB- renin receptor plays an important role in the development of nephropathy . Although renal mRNA expression of the -LRB- pro -RRB- renin receptor was similar in the control and diabetic rats -LSB- 17 -RSB- , nonproteolytically activated prorenin increased in the kidneys of the diabetic rats , and this increase was inhibited by the handle region peptide . In addition , the renal total renin content remained unchanged during the treatment with the handle region peptide . These results suggested that the handle region peptide inhibits the conformational change in prorenin that leads to prorenin 's enzymatic activation but does not alter the prorenin levels . Because the mRNA expression of cathepsin B , which processes the conversion of prorenin to renin , simultaneously decreased in the kidneys of the diabetic rats , prorenin may have accumulated in their kidneys . Also , the amount of prorenin released to the circulatory system may be elevated in diabetes leading to an elevation in receptor-bound prorenin as a result of the increased prorenin levels with no change in -LRB- pro -RRB- renin receptor expression . To investigate the contribution of angiotensin-II-independent , -LRB- pro -RRB- renin-receptor-dependent signal pathways to diabetic end-organ damage , the therapeutic effects of infusion were compared with the effect of the deletion of angiotensin II type 1a receptor -LRB- ATKO -RRB- and ACE inhibition on streptozotosin-induced type I diabetes -LSB- 18 -RSB- . Deletion of the angiotensin II type 1 gene attenuated the development of glomerulosclerosis and proteinuria but did not prevent these developments . ACE inhibitor also failed to prevent diabetic nephropathy despite the normalization of renal angiotensin II . On the other hand , the handle region peptide almost completely prevented the development of these conditions despite the absence of an increase in renal angiotensin levels . Of note , MAPKs were markedly activated in diabetic ATKO animals and , while the handle region peptide almost completely inhibited the activation , ACE inhibition failed to even ameliorate it . These results indicate that inhibition of the angiotensin-II-mediated pathway had a little therapeutic effect on nephropathy in the diabetic rats , whereas the blockade of receptor-bound prorenin seemed to suppress the two major pathways for diabetic nephropathy : excessive production of angiotensin II in the kidneys and renal MAPK activation . In this experiment , the renal angiotensin II levels of diabetic mice treated with the handle region peptide were similar to those of untreated wild-type mice . Because the handle region peptide did not seem to inhibit the binding of renin to the -LRB- pro -RRB- renin receptor , the physiological production of renal angiotensin II induced by renin or receptor-bound renin was probably unaffected by the handle-region-peptide-induced inhibition of receptor-bound prorenin . In addition , the handle region peptide did not influence the plasma levels of renin and prorenin -LRB- receptor-unbound free renin and receptor-unbound free prorenin -RRB- or blood pressure . Thus , the handle region peptide also had no effect on the physiology of the circulating renin -- angiotensin system . We recently found that the handle region peptide also leads to the regression of nephropathy in rats with streptozotosin-induced type I diabetes -LSB- 17 -RSB- . Diabetes was induced by streptozotosin injection in 4-week-old rats . Increased urinary protein excretion and glomerulosclerosis were observed 12weeks later and the administration of the handle region peptide or vehicle was started . While urinary protein excretion and glomerulosclerosis had progressed in vehicle-treated 28-week-old diabetic rats , treatment with the handle region peptide significantly reduced the proteinuria and glomerulosclerosis from the levels observed at the start of treatment . This reversal of the glomerulosclerosis that had already developed in the diabetic rats suggested that receptor-bound prorenin contributes not only to the onset of nephropathy but also to its progression . The increased plasma prorenin level might be supplied by the kidneys in which high glucose levels might inhibit the processing of prorenin to renin as described above . In addition , extrarenal tissues might also be sources of the increased prorenin level under high glucose conditions because plasma prorenin is detectable even after a bilateral nephrectomy -LSB- 15 -RSB- . Thus , high glucose levels may contribute to an increase in the plasma prorenin level via both renal and extrarenal mechanisms , and the elevated plasma prorenin level might trigger an increase in receptor-bound prorenin leading to nephropathy . These mechanisms may explain why the handle region peptide inhibited the development and progression of nephropathy in animal models of diabetes without affecting the high blood glucose level . Further study is needed to clarify these points . Receptor-bound prorenin in hypertensive kidneys SHRsp rats have high plasma levels of prorenin and renin and are used as a model of primary hypertension -LSB- 19 -RSB- . In addition to the increased mRNA expression of the -LRB- pro -RRB- renin receptor as described above , elevated angiotensin I and II levels and glomerulosclerosis with proteinuria have been observed in the kidneys of young hypertensive SHRsp ; administration of the handle region peptide significantly suppressed these changes without affecting the development of hypertension -LSB- 7 -RSB- . In addition , profibrotic changes in morphology were observed in the clipped kidneys of Goldblatt hypertensive rats with enhanced mRNA expression of the -LRB- pro -RRB- renin receptor -LSB- 9 -RSB- . Therefore , the increased expression of the -LRB- pro -RRB- renin receptor may play an important role in the development of renal tissues showing characteristic signs of hypertensive damage . Because recent studies have demonstrated the presence of angiotensin-II-independent , -LRB- pro -RRB- renin-receptor-dependent MAPK pathways in mesangial cells -LSB- 20 -RSB- and vascular smooth muscle cells -LSB- 21 -RSB- , the beneficial effects of the handle region peptide may be mediated by both of these two major pathways that are stimulated by receptor-bound prorenin . Thus , receptor-bound prorenin also contributes to the development of hypertensive end-organ damage . This was recently supported , in part , by Susic et al. , who reported that the handle region peptide significantly reduced the left ventricular mass even though the myocardial collagen content remained unchanged -LSB- 22 -RSB- . Possible inhibition of receptor-bound prorenin by high levels of renin Figure 2 shows the binding of renin and prorenin to the -LRB- pro -RRB- renin receptor . Because both renin and prorenin bind to the -LRB- pro -RRB- renin receptor -LSB- 3 -RSB- , increased renin levels may increase the amount of renin and decrease the amount of prorenin that binds to the receptor . A recent review reported that the handle region peptide offered no benefit to renin-transgenic models or to a model with renovascular hypertension -LSB- 23 -RSB- . Because the ratio of renin to prorenin must be higher in these models than in control models , renin -- but not prorenin -- that has bound to the receptor must contribute to the pathogenesis that occurs in these models . Because no data showed the blockade of renin signaling by the handle region peptide , the handle region peptide did not benefit the renin-transgenic models or the model with renovascular hypertension -LSB- 23 -RSB- . In contrast , the handle region peptide greatly benefited diabetic animals -LSB- 16 -- 18 -RSB- . Because diabetic animals are known to have a low ratio of renin to prorenin -LSB- 15 -RSB- , they have increased levels of prorenin bound to the receptor and decreased levels of renin bound to the receptor . Thus , the handle region peptide was thought to benefit in vivo diabetic animals by reducing the amount of prorenin that bound to the receptor . In addition , the handle region peptide had a partial benefit on SHRsp -LSB- 7 , 24 -RSB- and SHR -LSB- 22 -RSB- animals fed a high-salt diet . This benefit was reduced by changing from a high-salt diet to a low-salt diet -LRB- unpublished preliminary data -RRB- , suggesting that dietary salt might alter the levels of prorenin bound to the receptor by regulating the renin levels . Thus , the efficiency of the handle region peptide may depend on the ratio of renin to prorenin . Fig. 2Renin and prorenin competitively bind to the -LRB- pro -RRB- renin receptor in vivo and to the -LRB- pro -RRB- renin receptor expressed on the cell surfaces of COS-7 cells -LRB- Pro -RRB- renin receptors in cultured cells Using vascular smooth muscle cells -LRB- VSMC -RRB- harvested from human - -LRB- pro -RRB- renin-receptor-transgenic rats , Batenburg et al. recently demonstrated that prorenin binds to the -LRB- pro -RRB- renin receptor and that receptor-bound prorenin exerts a catalytic activity but that renin does not bind to the receptor or increase its own catalytic activity -LSB- 25 -RSB- , consistent with the results of a previous study using human VSMC -LSB- 21 -RSB- . The structural difference between renin and prorenin arises from 43 amino acids in the prorenin prosegment and prorenin acquires its catalytic activity without changing its molecular weight when a specific protein binds to the `` handle '' region of the prorenin prosegment -LSB- 1 -RSB- . Nevertheless , the handle region decoy peptide , which inhibited the binding of prorenin to the receptor in a test tube and to receptors expressed on the cell surfaces of COS-7 cells -LSB- 13 -RSB- , failed to inhibit prorenin 's acquisition of catalytic activity by binding to the receptor -LSB- 25 -RSB- . A recent study using a human cultured cell line clearly demonstrated that the 39-kDa full-length -LRB- pro -RRB- renin receptor was predominantly present in the intracellular endoplasmic reticulum -LSB- 8 -RSB- . Because both renin and prorenin can permeate the cell membrane -LSB- 8 -RSB- but the handle region peptide can not , the handle region peptide might be incapable of inhibiting intracellular binding between the -LRB- pro -RRB- renin receptor and its ligands -LRB- Fig. 3 -RRB- . Fig. 3Possible fragmentation of -LRB- pro -RRB- renin receptor in cultured cells Although -LRB- pro -RRB- renin receptors of VSMC harvested from human - -LRB- pro -RRB- renin-receptor-transgenic rats were not bound to renin -LSB- 25 -RSB- , the same authors also showed that both renin and prorenin bind to the -LRB- pro -RRB- renin receptor and stimulate receptor-dependent ERK pathways in U937 monocytes -LSB- 26 -RSB- . In addition , a renin-stimulated , -LRB- pro -RRB- renin-receptor-dependent ERK pathway was observed in rat and human mesangial cells -LSB- 4 , 20 -RSB- , whereas the stimulation of the receptor by prorenin in cultured cardiomyocytes resulted in the activation of p-38 MAPK , but not ERK -LSB- 27 -RSB- , and renin stimulation caused the interaction between the receptor and the transcription factor promyelocytic zinc finger protein in HeLa-S3 cells and HEK293 cells -LSB- 8 -RSB- . These results suggest that the ability to bind renin and prorenin and the intracellular pathways involving these proteins may be influenced by the species and condition of the cultured cells . In addition , the presence of -LRB- pro -RRB- renin receptors with molecular weights smaller than the 39kDa of the full-length receptor in cultured cells has been reported in abstracts presented at several meetings . Based on the results of all these studies regarding the -LRB- pro -RRB- renin receptor in cultured cells , we propose the possible fragmentation of the -LRB- pro -RRB- renin receptor -LRB- Fig. 3 -RRB- . Namely , when the 39-kDa full-length -LRB- pro -RRB- renin receptor in the endoplasmic reticulum is released to the cytoplasm , it may divide into a renin-binding part and a remnant part . In the cytoplasm of VSMC and cardiomyocytes , the remaining smaller -LRB- pro -RRB- renin receptor without the renin-binding part would be capable of binding prorenin but would be incapable of binding renin . However , in the cytoplasm of the mesangium and monocytes , the smaller receptor might readhere to the renin-binding part and resume its ability to bind renin . When the smaller receptor in the cytoplasm reaches the cell membrane , it might further divide into the prorenin-binding part , recognizing the `` handle '' region , and a remnant part . The prorenin-binding part would be released to the extracellular area and the smallest remnant receptor would remain at the cell membrane . Because the smallest receptor does not contain either the renin-binding part or the prorenin-binding part , it would no longer be capable of binding renin or prorenin . When the prorenin bound to the smaller receptor also reaches the cell membrane , it would divide into three parts : the prorenin prosegment adhered to the prorenin-binding part , renin , and the remaining smallest receptor . Because the former two proteins are released to the extracellular area , angiotensin I generation from external angiotensinogen would occur there . Thus , under cultured cell conditions , the -LRB- pro -RRB- renin receptor may be fragmented depending on the cell species . Further studies are needed to verify the possible fragmentation of the -LRB- pro -RRB- renin receptor . Conclusion In the glomerulus of the kidneys , the -LRB- pro -RRB- renin receptor is not only present in the mesangium but is also abundant in the podocytes and its expression was increased by two - to threefold in the kidneys of some animal models of hypertension . A transgene-induced overexpression of human -LRB- pro -RRB- renin receptor in rats resulted in the development of slowly progressive nephropathy with proteinuria . In addition , the handle-region-peptide-induced inhibition of receptor-bound prorenin significantly inhibited the development and progression of proteinuria in experimental diabetic and hypertensive animal models . Thus , the glomerular -LRB- pro -RRB- renin receptor appears to play an important role in the regulation of the glomerular filtration barrier .

O O O O O O O O O O O O O O O O O B O O O O O O B O O O B I O B O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O B O O O O O O O O B O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O 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O O O O O O O O O O O O B O O O O O O O O O O O O O O O O B O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O B O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O B O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O B O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O B O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O B O O B O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O B O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O

angiotensin
nonproteolytic activation
podocytes
prorenin