Requirement for class II phosphoinositide 3-kinase C2alpha in maintenance of glomerular structure and function.
An early lesion in many kidney diseases is damage to podocytes, which are critical components of the glomerular filtration barrier. A number of proteins are essential for podocyte filtration function, but the signaling events contributing to development of nephrotic syndrome are not well defined. Here we show that class II phosphoinositide 3-kinase C2α (PI3KC2α) is expressed in podocytes and plays a critical role in maintaining normal renal homeostasis. PI3KC2α-deficient mice developed chronic renal failure and exhibited a range of kidney lesions, including glomerular crescent formation and renal tubule defects in early disease, which progressed to diffuse mesangial sclerosis, with reduced podocytes, widespread effacement of foot processes, and modest proteinuria. These findings were associated with altered expression of nephrin, synaptopodin, WT-1, and desmin, indicating that PI3KC2α deficiency specifically impacts podocyte morphology and function. Deposition of glomerular IgA was observed in knockout mice; importantly, however, the development of severe glomerulonephropathy preceded IgA production, indicating that nephropathy was not directly IgA mediated. PI3KC2α deficiency did not affect immune responses, and bone marrow transplantation studies also indicated that the glomerulonephropathy was not the direct consequence of an immune-mediated disease. Thus, PI3KC2α is critical for maintenance of normal glomerular structure and function by supporting normal podocyte function.
Harris
David P
DP
Lexicon Pharmaceuticals, Inc., 8800 Technology Forest Place, The Woodlands, TX 77381, USA. dpharris@lexpharma.com
Vogel
Peter
P
Wims
Marie
M
Moberg
Karen
K
Humphries
Juliane
J
Jhaver
Kanchan G
KG
DaCosta
Christopher M
CM
Shadoan
Melanie K
MK
Xu
Nianhua
N
Hansen
Gwenn M
GM
Balakrishnan
Sanjeevi
S
Domin
Jan
J
Powell
David R
DR
Oravecz
Tamas
T
D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism; D016026:Bone Marrow Transplantation; D005921:Glomerulonephritis / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D005922:Glomerulonephritis, IGA / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D007070:Immunoglobulin A / Q000378:metabolism; D007074:Immunoglobulin G / Q000378:metabolism; D007678:Kidney Glomerulus / Q000033:anatomy & histology* / Q000201:enzymology / Q000473:pathology / Q000502:physiology*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008840:Microfilament Proteins / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D050199:Podocytes / Q000201:enzymology / Q000473:pathology / Q000502:physiology; D051437:Renal Insufficiency / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D018183:Transplantation Chimera
D000954:Antigens, Surface; D007070:Immunoglobulin A; D007074:Immunoglobulin G; C095910:MECA-32 antigen, mouse; D008565:Membrane Proteins; D008840:Microfilament Proteins; C503968:Synpo protein, mouse; C113267:nephrin; D019869:Phosphatidylinositol 3-Kinases; C546635:Pik3c2a protein, mouse