Enhanced expression of STIM1/Orai1 and TRPC3 in platelets from patients with type 2 diabetes mellitus.

Type 2 diabetes mellitus (DM2) is a metabolic syndrome that contributes to both macrovascular and microvascular disorders, where platelet hyperaggregability, associated to abnormal intracellular Ca(2+) homeostasis, plays an important role. We have now investigated the expression of different proteins associated to Ca(2+) entry, a major Ca(2+) signalling event. DM2 donors were randomly selected from normotensive patients with glycosylated Hb levels (HbA1c) over 6%. Control subjects were normal age- and gender-matched healthy people with HbA1c levels in the normal range (3.5-5%). Expression of TRPC1, 3 and 6, STIM1 and Orai1 was analyzed by Western blotting in DM2 patients and controls. Expression of TRPC1 in platelets from DM2 donors and controls was similar; however, expression of TRPC6 is reduced in platelets from DM2 patients as compared to healthy controls. We have found that expression of TRPC3, Orai1 and STIM1 is enhanced in DM2 subjects as compared to controls. Our findings provide an explanation to the enhanced Ca(2+) entry induced by physiological agonists in platelets from DM2 patients.