Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0002895 (sickle cell disease)
 11,747 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phosphatidylserine (PS) externalization may contribute to Sickle Cell Disease (SCD) characteristics including thrombogenesis, endothelial adhesion and shortened red blood cell (RBC) lifespan. Aminophospholipid translocase (APLT) returns externalized PS to the inner membrane, and phospholipid scramblase (PLSCR) equilibrates phospholipids (PL) across the membrane. APLT inhibition and PLSCR activation appear to be important for PS externalization. We examined relationships between APLT, PLSCR and external PS in mature sickle RBC and reticulocytes. Normally-hydrated sickle RBC without external PS had active APLT and inactive PLSCR. PS-exposing sickle RBC had inhibited APLT and active PLSCR. Sickle reticulocytes had active APLT and active PLSCR independent of external PS. Sickle RBC dehydrated in vivo had the highest proportion of PS-exposing RBC and markedly inhibited APLT. Normal and sickle RBC dehydrated in vitro had moderately decreased APLT. Rehydration resulted in significant recovery of APLT in RBC previously dehydrated in vitro, but not in sickle RBC dehydrated in vivo. These findings indicate that (i) PS externalization in mature sickle RBC depends on the balance between APLT and PLSCR activities, (ii) PS externalization in sickle reticulocytes depends primarily on PLSCR activation and (iii) APLT inhibition in sickle RBC dehydrated in vivo is due to dehydration itself and other factors.
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PMID:Aminophospholipid translocase and phospholipid scramblase activities in sickle erythrocyte subpopulations. 1954 70

Externalization of phosphatidylserine (PS) is thought to contribute to sickle cell disease (SCD) pathophysiology. The red blood cell (RBC) aminophospholipid translocase (APLT) mediates the transport of PS from the outer to the inner RBC membrane leaflet to maintain an asymmetric distribution of PL, while phospholipid scramblase (PLSCR) equilibrates PL across the RBC membrane, promoting PS externalization. We previously identified an association between PS externalization level and PLSCR activity in sickle RBC under basal conditions. Other studies showed that activation of protein kinase C (PKC) by PMA (phorbol-12-myristate-13-acetate) causes increased external PS on RBC. Therefore, we hypothesized that PMA-activated PKC stimulates PLSCR activity in RBC and thereby contributes to increased PS externalization. In the current studies, we show that PMA treatment causes immediate and variable PLSCR activation and subsequent PS externalization in control and sickle RBC. While TfR+ sickle reticulocytes display some endogenous PLSCR activity, we observed a robust activation of PLSCR in sickle reticulocytes treated with PMA. The PKC inhibitor, chelerythrine (Chel), significantly inhibited PMA-dependent PLSCR activation and PS externalization. Chel also inhibited endogenous PLSCR activity in sickle reticulocytes. These data provide evidence that PKC mediates PS externalization in RBC through activation of PLSCR.
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PMID:Activation of protein kinase C by phorbol ester increases red blood cell scramblase activity and external phosphatidylserine. 2560 Apr 60