Differential effects of adenylyl cyclase-protein kinase A cascade on shear-induced changes of sickle cell...

Erythrocyte deformability is impaired in sickle cell disease (SCD). The regulation of cytoskeletal protein organization plays a key role in erythrocyte deformability. The activation of adenylyl cyclase (AC)/cAMP/Protein kinase A (PKA) signaling pathway was associated with increased deformability in healthy erythrocytes, however the role of this pathway in SCD is unknown.

We evaluated mechanical responses of sickle red blood cells under physiological levels of shear stress and the possible link between their deformability and AC/cAMP/PKA signaling pathway.

The shearing of sickle red blood cells at physiological level (5 Pa) and the measurement of deformability were performed by a laser assisted optical rotational cell analyzer (LORRCA).

Red blood cell deformability increased of 2.5-6.5% by blocking the activity of phosphodiesterase with Pentoxifylline (10μM) (p < 0.05). The inhibition of AC with SQ22536 (100μM) produced more significant rise in deformability (+4.8-12%, p < 0.01). No significant change was observed by the inhibition of PKA with H89 (10μM).

Pentoxifylline and SQ22536 increased the deformability of sickle red blood cells under fluid shear stress. Modulation of the AC/cAMP/PKA pathway could have the potential to be an effective therapeutic approach for SCD through shear-induced improvements of RBC deformability.