Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.23.15 (renin)
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Advances in the molecular genetics of inherited renal tubulopathies have allowed some insight into the normal mechanisms of tubular cation and anion reabsorption. It is now possible to view Bartter's syndrome, Gitelman's syndrome and pseudohypoaldosteronism type 1 as having genetic abnormalities which produce tubular defects that are similar to those induced by the pharmacological actions of loop diuretics, thiazide diuretics or potassium-sparing diuretics, respectively. Although these rare monogenic disorders with dramatic phenotypes seem to have little relevance to everyday clinical practice, it is possible that subtle abnormalities of the regulation of the ENaCs may play a role in low-renin forms of 'essential' hypertension. Similarly, subtle abnormalities in the function of the electroneutral sodium-(potassium)-chloride cotransporters (NKCC2 and NCCT) and the renal CLC-type chloride channels (CLC5) may be major determinants of urinary calcium excretion with roles in the pathogenesis of 'idiopathic' hypercalciuria and osteoporosis. Because of the intricate and diverse molecular mechanisms by which tubular reabsorption of water and solutes takes place in each different nephron segment, it is likely that other renal channels and transporters will be implicated in the pathogenesis of further monogenic disorders, and that these will allow additional insights into tubular functioning. Recent studies have demonstrated that in addition to abnormalities in the NKCC2 and ROMK1 genes, mutations at a third genetic locus can also cause Bartter's syndrome. Linkage studies, followed by mutational analyses have found deletions and point mutations in the gene encoding one of the TAL-specific chloride channels, CLCKB, in 17 Bartter's families. This chloride channel is similar in structure to CLC5, and is located on the long arm of chromosome 1. Importantly, there appears to be a phenotypic difference between subjects with Bartter's syndrome due to CLCKB abnormalities and those with NKCC2 or ROMK1 mutations. Despite the fact that all of these Bartter's patients had significant hypercalciuria, nephrocalcinosis was not found in any of the 17 subjects with CLCKB mutations, compared to 19 of 20 patients with NKCC2 or ROMK1 mutations. These findings have also demonstrated a key role for CLCKB as a major basolateral chloride channel involved in mTAL sodium and chloride reabsorption (Figure 2).
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PMID:Straightening out the renal tubule: advances in the molecular basis of the inherited tubulopathies. 951 7

A high salt intake has been correlated with several pathological conditions such as hypertension, cardiovascular disease, renal calcium stones, and osteoporosis. Some of these diseases present a high prevalence in the elderly and common pathogenetic mechanisms are proposed for some of them. A high salt intake has been associated with hypertension as well as osteoporosis and one of the proposed pathogenetic mechanisms is an increased calcium excretion in urine. Urinary calcium loss induces a negative calcium balance that may predispose hypertensive subjects to developing greater bone loss. The gene which encodes for the thiazide- sensitive sodium-chloride cotransporter (NCCT) represents a possible link between hypertension and osteoporosis. Subjects heterozygous for an inactivating mutation of NCCT present a positive effect on bone density as shown by the significantly higher Z-scores at the lumbar spine and total femur. Recent clinical studies also support the benefit of ACE inhibitors in reducing fracture risk or improving bone metabolism. These data suggest that the renin-angiotensin system may be one of the several factors involved in bone metabolism. Hypertension, together with stroke, has been demonstrated to be a risk factor for osteoporosis. Although the risk associated with hypertension was limited in terms of relative risk, it may have a significant impact on the general population owing to the high prevalence of hypertension. The treatment of hypertension may thus be very useful in also giving protection against fractures.
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PMID:Salt intake, hypertension, and osteoporosis. 1972 61