Iron control of erythroid microtubule cytoskeleton as a potential target in treatment of iron-restricted anemia.

Anemias of chronic disease and inflammation (ACDI) result from restricted iron delivery to erythroid progenitors. The current studies reveal an organellar response in erythroid iron restriction consisting of disassembly of the microtubule cytoskeleton and associated Golgi disruption. Isocitrate supplementation, known to abrogate the erythroid iron restriction response, induces reassembly of microtubules and Golgi in iron deprived progenitors. Ferritin, based on proteomic profiles, regulation by iron and isocitrate, and putative interaction with microtubules, is assessed as a candidate mediator. Knockdown of ferritin heavy chain (FTH1) in iron replete progenitors induces microtubule collapse and erythropoietic blockade; conversely, enforced ferritin expression rescues erythroid differentiation under conditions of iron restriction. Fumarate, a known ferritin inducer, synergizes with isocitrate in reversing molecular and cellular defects of iron restriction and in oral remediation of murine anemia. These findings identify a cytoskeletal component of erythroid iron restriction and demonstrate potential for its therapeutic targeting in ACDI.

Induced plasma expander-like properties as a function of PEG-chains on extension arm facilitated PEGylation of albumin: "mushroom to brush-like" conformational transition of the PEG-albumin conjugate.

Plasma expander-like properties of albumin induced on hexa as well as dodecacPEGylation using Extension Arm Facilitated PEGylation platform make it an excellent resuscitation fluid. PEGylation induced changes in the structure, drug binding, and plasma expander-like properties of bovine serum albumin has been now investigated as a function of PEGylation. The molecular volume of albumin increases on PEGylation nearly linearly; in the beginning up to about six PEG chains are conjugated, then plateau off, while the viscosity and colloidal osmotic pressure change very little initially and then increase exponentially as a function of PEG chains conjugated. PEGylation has essentially no influence on the secondary structure or drug properties of albumin. Tryphtophyl fluorescence of albumin is quenched on PEGylation as a direct correlate of the changes in molecular radius of PEG-albumin. It is concluded that hexaPEGylated and dodecaPEGylated albumin belong to two different configurational states of PEG-albumin in terms of packing of PEG-chains on the molecular surface of the protein. The results suggest a transition of PEGylated albumin from the initial mushroom-like conformation to brush conformation as the PEGylation increases. The therapeutic efficacy of the two PEGylated species is needed to establish the optimum level of PEGylation to function as resuscitation fluids.