title: Knockdown of Expression of Cdk5 or p35 (a Cdk5 Activator) Results in Podocyte Apoptosis.
abstract: Podocytes are terminally differentiated glomerular epithelial cells. Podocyte loss has been found in many renal diseases. Cdk5 is a cyclin-dependent protein kinase which is predominantly regulated by p35. To study the role of Cdk5/p35 in podocyte survival, we first applied western blotting (WB) analysis to confirm the time-course expression of Cdk5 and p35 during kidney development and in cultured immortalized mouse podocytes. We also demonstrated that p35 plays an important role in promoting podocyte differentiation by overexpression of p35 in podocytes. To deregulate the expression of Cdk5 or p35 in mouse podocytes, we used RNAi and analyzed cell function and apoptosis assaying for podocyte specific marker Wilms Tumor 1 (WT1) and cleaved caspase 3, respectively. We also counted viable cells using cell counting kit-8. We found that depletion of Cdk5 causes decreased expression of WT1 and apoptosis. It is noteworthy, however, that downregulation of p35 reduced Cdk5 activity, but had no effect on cleaved caspase 3 expression. It did, however, reduce expression of WT1, a transcription factor, and produced podocyte dysmorphism. On the other hand increased apoptosis could be detected in p35-deregulated podocytes using the TUNEL analysis and immunofluorescent staining with cleaved caspase3 antibody. Viability of podocytes was decreased in both Cdk5 and p35 knockdown cells. Knocking down Cdk5 or p35 gene by RNAi does not affect the cycline I expression, another Cdk5 activator in podocyes. We conclude that Cdk5 and p35 play a crucial role in maintaining podocyte differentiation and survival, and suggest these proteins as targets for therapeutic intervention in podocyte-damaged kidney diseases.
authors.affiliation: Department of Nephrology, Ningxia People's Hospital (First Affiliated Hospital of Medical College, Northwest University for Nationalities), Yinchuan, Ningxia Province, 750002, China.
authors.forename: Ya-Li
authors.initials: YL
authors.lastname: Zheng
authors.affiliation: Department of Nephrology, Ningxia People's Hospital (First Affiliated Hospital of Medical College, Northwest University for Nationalities), Yinchuan, Ningxia Province, 750002, China.
authors.forename: Xia
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Center of Blood Purification, Central Hospital of Rizhao City, Rizhao, Shangdong Province, 276800, China.
authors.forename: Hai-Xia
authors.initials: HX
authors.lastname: Fu
authors.affiliation: Zhongshan-Xuhui hospital affiliated Fudan University, Shanghai, 200031, China.
authors.forename: Mei
authors.initials: M
authors.lastname: Guo
authors.affiliation: Laboratory of Neurochemistry, National Institute of Neurological Disorders and Stroke (NINDS), Bethesda, MD, 20814, United States of America.
authors.forename: Varsha
authors.initials: V
authors.lastname: Shukla
authors.affiliation: Laboratory of Neurochemistry, National Institute of Neurological Disorders and Stroke (NINDS), Bethesda, MD, 20814, United States of America.
authors.forename: Niranjana D
authors.initials: ND
authors.lastname: Amin
authors.affiliation: Department of Nephrology, Ningxia People's Hospital (First Affiliated Hospital of Medical College, Northwest University for Nationalities), Yinchuan, Ningxia Province, 750002, China.
authors.forename: Jing
authors.initials: J
authors.lastname: E
authors.affiliation: Department of Nephrology, Ningxia People's Hospital (First Affiliated Hospital of Medical College, Northwest University for Nationalities), Yinchuan, Ningxia Province, 750002, China.
authors.forename: Li
authors.initials: L
authors.lastname: Bao
authors.affiliation: Department of Nephrology, Ningxia People's Hospital (First Affiliated Hospital of Medical College, Northwest University for Nationalities), Yinchuan, Ningxia Province, 750002, China.
authors.forename: Hong-Yan
authors.initials: HY
authors.lastname: Luo
authors.affiliation: Department of Nephrology, Ningxia People's Hospital (First Affiliated Hospital of Medical College, Northwest University for Nationalities), Yinchuan, Ningxia Province, 750002, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.affiliation: Department of Nephrology, Ningxia People's Hospital (First Affiliated Hospital of Medical College, Northwest University for Nationalities), Yinchuan, Ningxia Province, 750002, China.
authors.forename: Xiao-Hua
authors.initials: XH
authors.lastname: Lu
authors.affiliation: Department of Nephrology, Ningxia People's Hospital (First Affiliated Hospital of Medical College, Northwest University for Nationalities), Yinchuan, Ningxia Province, 750002, China.
authors.forename: Yong-Cai
authors.initials: YC
authors.lastname: Gao
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D053148:Caspase 3 / Q000378:metabolism; D002454:Cell Differentiation; D002478:Cells, Cultured; D051360:Cyclin-Dependent Kinase 5 / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics; D055785:Gene Knockdown Techniques; D007678:Kidney Glomerulus / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*; D050199:Podocytes / Q000166:cytology / Q000378:metabolism / Q000473:pathology*; D011247:Pregnancy; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D013997:Time Factors; D025721:WT1 Proteins
chemical_list: D009419:Nerve Tissue Proteins; D034741:RNA, Small Interfering; D012097:Repressor Proteins; D025721:WT1 Proteins; C000602896:WT1 protein, mouse; C089495:neuronal Cdk5 activator (p25-p35); D051360:Cyclin-Dependent Kinase 5; D053148:Caspase 3