Dysregulation of erythropoiesis and altered erythroblastic NMDA receptor-mediated calcium influx in Lrfn2-deficient mice.

Ryuta Maekawa,Minoru Hatayama,Jun Aruga,Hideki Muto

doi:10.1371/journal.pone.0245624

Abstract

LRFN2 encodes a synaptic adhesion-like molecule that physically interacts with N-methyl-D-aspartate (NMDA) receptor 1 and its scaffold proteins. Previous studies in humans and mice have demonstrated its genetic association with neurodevelopmental disorders such as learning deficiency and autism. In this study, we showed that Lrfn2-deficient (KO) mice exhibit abnormalities of erythropoietic systems due to altered NMDA receptor function. In mature Lrfn2 KO male mice, peripheral blood tests showed multilineage abnormalities, including normocytic erythrocythemia, and reduced platelet volume. Colony forming unit assay using bone marrow cells revealed decreases in the counts of erythrocyte progenitors (CFU-E) as well as granulocytes and monocyte progenitors (CFU-GM). Whole bone marrow cell staining showed that serum erythropoietin (EPO) level was decreased and EPO receptor-like immunoreactivity was increased. Flow cytometry analysis of bone marrow cells revealed increased early erythroblast count and increased transferrin receptor expression in late erythroblasts. Further, we found that late erythroblasts in Lrfn2 KO exhibited defective NMDA receptor-mediated calcium influx, which was inhibited by the NMDA receptor antagonist MK801. These results indicate that Lrfn2 has biphasic roles in hematopoiesis and is associated with the functional integrity of NMDA receptors in hematopoietic cells. Furthermore, taken together with previous studies that showed the involvement of NMDA receptors in hematopoiesis, the results of this study indicate that Lrfn2 may regulate erythropoiesis through its regulatory activity on NMDA receptors.

Highlights

Lrfn2 is a member of the Lrfn family proteins, which are known to be cell adhesion molecules that regulate neuronal and synaptic development in the brain [1]
In mid erythroblasts (EryB) of the 19–22 M age group, the variance of NMDA/GLY was larger in KO cells than that in Wild type (WT) cells (P = 0.0027 in f-test). These results indicated that Lrfn2 KO bone marrow (BM) cells had impaired NMDAR function in late erythroblasts, consistent with the larger NMDA/GLY response variance (6–12 M, P = 0.0063 in f-test) and MK-801-induced suppression variance (19–22 M, P = 0.021 in ftest) in WT erythroid cells (TER119+) compared to those in KO erythroid cells; the NMDA receptor functions were limited to late (6–12 M and 19–22 M) or mid (19–22 M) erythroblasts
This study revealed the importance of Lrfn2 in the regulation of erythropoiesis

Summary

Introduction

Lrfn ( known as SALM [synaptic adhesion like molecule] 1) is a member of the Lrfn family proteins, which are known to be cell adhesion molecules that regulate neuronal and synaptic development in the brain [1]. Lrfn physically interacts with ion channels forming a glutamate receptor called N-methyl-D-aspartate receptor 1 (NMDAR1, known as GluN1 or Grin1) [1] as well as a synaptic scaffold protein PSD95 (post synaptic density protein 95, known as Dlg4) [1,2,3]. Recent genetic studies have linked human LRFN2 to autism-. Erythropoiesis and erythroblastic NMDAR-mediated calcium influx in Lrfn KO mice

Methods

Results

Conclusion