5,045 research outputs found

    Endo-lysosomal TRP mucolipin-1 channels trigger global ER Ca2+ release and Ca2+ influx.

    Get PDF
    Transient receptor potential (TRP) mucolipins (TRPMLs), encoded by the MCOLN genes, are patho-physiologically relevant endo-lysosomal ion channels crucial for membrane trafficking. Several lines of evidence suggest that TRPMLs mediate localised Ca(2+) release but their role in Ca(2+) signalling is not clear. Here, we show that activation of endogenous and recombinant TRPMLs with synthetic agonists evoked global Ca(2+) signals in human cells. These signals were blocked by a dominant-negative TRPML1 construct and a TRPML antagonist. We further show that, despite a predominant lysosomal localisation, TRPML1 supports both Ca(2+) release and Ca(2+) entry. Ca(2+) release required lysosomal and ER Ca(2+) stores suggesting that TRPMLs, like other endo-lysosomal Ca(2+) channels, are capable of 'chatter' with ER Ca(2+) channels. Our data identify new modalities for TRPML1 action

    An Endosomal NAADP-Sensitive Two-Pore Ca(2+) Channel Regulates ER-Endosome Membrane Contact Sites to Control Growth Factor Signaling.

    Get PDF
    Membrane contact sites are regions of close apposition between organelles that facilitate information transfer. Here, we reveal an essential role for Ca(2+) derived from the endo-lysosomal system in maintaining contact between endosomes and the endoplasmic reticulum (ER). Antagonizing action of the Ca(2+)-mobilizing messenger NAADP, inhibiting its target endo-lysosomal ion channel, TPC1, and buffering local Ca(2+) fluxes all clustered and enlarged late endosomes/lysosomes. We show that TPC1 localizes to ER-endosome contact sites and is required for their formation. Reducing NAADP-dependent contacts delayed EGF receptor de-phosphorylation consistent with close apposition of endocytosed receptors with the ER-localized phosphatase PTP1B. In accord, downstream MAP kinase activation and mobilization of ER Ca(2+) stores by EGF were exaggerated upon NAADP blockade. Membrane contact sites between endosomes and the ER thus emerge as Ca(2+)-dependent hubs for signaling

    Effect of soy on bone turn-over markers in men with type 2 diabetes and hypogonadism – a randomised controlled study

    Get PDF
    Type 2 diabetes (T2DM) is associated with increased risk of fractures. Soy supplementation has been shown to have a beneficial effect on bone turnover markers (BTM) in postmenopausal women. However, the effect of soy supplementation on BTM in T2DM and particularly in men is unclear. We performed an analysis of a randomized double blind parallel study of 200 men with T2DM treated with soy, either with or without isoflavones. Outcome measures were type I collagen crosslinked beta C-telopeptide (βCTX), and type 1 procollagen-N-propeptide (P1NP). The men, with a total testosterone <12 nmol/L, were treated with 15 g soy protein containing 66 mg of isoflavones (SPI) or 15 g soy protein alone without isoflavones (SP) daily for three months. There was a 15% reduction in βCTX after three months of SPI compared to SP supplementation. There was no significant difference in P1NP with either SPI or SP supplementation. There was a significant linear correlation between the reduction in βCTX in the SPI group with the reduction in HbA1c (r2 = 0.42; p = 0.04) and HOMA-IR (r2 = 0.54; p = 0.02). Our study indicates that there was a significant reduction in bone resorption following 3 months of SPI supplementation that correlated with an improvement of glycemic control in men with T2DM
    corecore