PATRICK MAYEUX

Email: patrick.mayeux@inserm.fr

Team: Study of normal and pathological erythropoiesis

Website: http://cochin.inserm.fr/

The team studies the regulation of the erythropoiesis with a special emphasis concerning the mechanism of action of erythropoietin. We have largely contributed to the identification of the intracellular relays activated downstream the erythropoietin receptor (EpoR), the mechanisms leading to their activation and their role in erythropoiesis. Duration of the activation of the receptors and their intracellular relays after hormone stimulation is often as important as the specificity of the intracellular relays that are activated to determine the cellular response to growth factor stimulation. We have shown that EpoR activation is rapidly turned off after Epo stimulation and we have identified a mechanism involving the ubiquitin ligase b-TRCP that plays a key role in EpoR down-regulation by inducing the proteasome-mediated degradation of its intracellular domain while the activated receptor is still in the plasma membrane. More recently, the team has shown that the EpoR associates with the type 2 transferrin receptor (TfR2) during its maturation in the endoplasmic reticulum to constitute a multimeric receptor. TfR2 is well known to constitute the iron sensor in hepatic cells allowing to regulate hepcidin production to circulating iron levels. The team now studies the role of this unexpected association of these two important receptors in erythroid cells.

Another important research focus of the team concerns the mechanisms leading to pathological erythropoiesis in myelodysplastic syndromes (MDS). Erythropoiesis in low grade MDS is characterized both by an increased apoptosis even in presence of high doses of erythropoietin and by dyserythropoiesis with maturation defects of erythroid progenitors. We have shown that increased apoptosis is mainly due to the overexpression of Fas and its ligand (FasL) during the terminal differentiation of erythroid progenitors. More recently, we have shown in collaboration with the team directed by O. Hermine, that dyserythropoiesis in MDS is at least partly due to a defect of HSP70 nuclear localization during the terminal differentiation steps leading to GATA1 degradation and maturation defects. Lastly, the team has developed tools to study erythropoietin structure, biological efficiency, mechanisms of action and degradation and the presence of Epo antibodies in patients treated with recombinant Epo.

Expertise

  1. Cell culture methods, starting from human primary cells, to analyze both normal and pathological erythropoiesis.
  2. Lentiviral vectors expression to inducibly or constitutively knockdown/increase specific proteins in primary human erythroid cells.
  3. Strong experience in biochemistry including: proteomics, cytokine mode of action, receptor expression and structure, apoptosis and intracellular signaling.

Main publications

  1. Gobert S, Chrétien S, Gouilleux F, Muller O, Pallard C, Dusanter-Fourt I, Groner B, Lacombe C, Gisselbrecht S, Mayeux P. Identification of tyrosine residues within the intracellular domain of the erythropoietin receptor crucial for STAT5  activation. The EMBO Journal. (1996);15:2434-2441.
  2. Verdier F, Walrafen P, Hubert N, Chretien S, Gisselbrecht S, Lacombe C, Mayeux P. Proteasomes regulate the duration of erythropoietin receptor activation by controlling down-regulation of cell surface receptors. J Biol Chem. (2000);275: p18375-18381.
  3. Casadevall N, Nataf J, Viron B, Kolta A, Kiladjian JJ, Martin-Dupont P, Michaud P, Papo T, Ugo V, Teyssandier I, Varet B, Mayeux P. Pure red-cell aplasia and antierythropoietin antibodies in patients treated with recombinant erythropoietin. N Engl J Med. (2002);346:469-475.
  4. Claessens YE, Bouscary D, Dupont JM, Picard F, Melle J, Gisselbrecht S, Lacombe C, Dreyfus F, Mayeux P, Fontenay-Roupie M. In vitro proliferation and differentiation of erythroid progenitors from patients with myelodysplastic syndromes: evidence for Fas-dependent apoptosis. Blood. (2002);99:1594-1601.
  5. Bouscary D, Pene F, Claessens YE, Muller O, Chretien S, Fontenay-Roupie M, Gisselbrecht S, Mayeux P, Lacombe C. Critical role for PI 3-kinase in the control of erythropoietin-induced erythroid progenitor proliferation. Blood. (2003);101.:3436-3443.
  6. Claessens YE, Park S, Dubart-Kupperschmitt A, Mariot V, Garrido C, Chretien S, Dreyfus F, Lacombe C, Mayeux P, Fontenay M. Rescue of early-stage myelodysplastic syndrome-deriving erythroid precursors by the ectopic expression of a dominant-negative form of FADD. Blood. (2005);105:4035-4042.
  7. Walrafen P, Verdier F, Kadri Z, Chretien S, Lacombe C, Mayeux P. Both proteasomes and lysosomes degrade the activated erythropoietin receptor. Blood. (2005);105:600-608.
  8. Meyer L, Deau B, Forejtnikova H, Dumenil D, Margottin-Goguet F, Lacombe C, Mayeux P, Verdier F. beta-Trcp mediates ubiquitination and degradation of the erythropoietin receptor and controls cell proliferation. Blood. (2007);109:5215-5222.
  9. Forejtnikova H, Vieillevoye M, Zermati Y, Lambert M, Pellegrino RM, Guihard S, Gaudry M, Camaschella C, Lacombe C, Roetto A, Mayeux P, Verdier F. Transferrin receptor 2 is a component of the erythropoietin receptor complex and is required for efficient erythropoiesis. Blood. (2010);116:5357-5367.
  10. Frisan E, Vandekerckhove J, de Thonel A, Pierre-Eugene C, Sternberg A, Arlet JB, Floquet C, Gyan E, Kosmider O, Dreyfus F, Gabet AS, Courtois G, Vyas P, Ribeil JA, Zermati Y, Lacombe C, Mayeux P, Solary E, Garrido C, Hermine O, Fontenay M. Defective nuclear localization of Hsp70 is associated with dyserythropoiesis and GATA-1 cleavage in myelodysplastic syndromes. Blood. (2012);119:1532-1542.