The excessive production and accumulation of beta-amyloid (Abeta) peptides within the brain is believed to initiate the pathological cascade culminating in Alzheimer Disease (AD). Autosomal dominant forms of AD appear to cause disease by promoting Abeta production, especially Abeta42. Abeta is derived from the proteolytic cleavage of beta-amyloid precursor protein (betaAPP) by beta- and gamma-secretase activities. Inhibiting either secretase is a major goal in AD therapeutics. Beta-secretase was recently identified, gamma-secretase, which is responsible for Abeta42 generation, has not been identified, though presenilin 1 was shown to be a central component of gamma-secretase which probably consists of a complex of proteins. Thus, the further elucidation of a gamma-secretase complex, as well as the discovery of proteins (genes) that influence either beta- or gamma-secretase activities, are major goals in AD research. Random Homozygous Knockout (RHKO) is a genetic approach designed to discover genes based on their biological function and has been successfully used to identify genes involved in tumorigenesis, ubiquitin-mediated protein degradation and resistance to infectious agents. Specifically, RHKO accomplishes random inactivation of both alleles of chromosomal genes by using gene search (retroviral) vector cassettes that contain a regulated antisense promoter. Hence, an inactivated gene can later be turned on to validate the knockout. Also, a tag is included in the vector so the gene can be easily isolated. A recent version of RHKO causes transfected cells to produce circularized plasmids containing the targeted gene, which can be used to transform bacteria for rapid DNA cloning. A modified version of RHKO will be used to identify genes whose inactivation alters beta- and gamma-secretase activities in several newly developed assay systems. The effects of such genes on Abeta generation will be validated in a tetracycline regulated cell culture systems. Cell biological characteristics of the gene products will be studied in cell culture systems and in transgenic mouse models. The results are expected to illuminate genetic pathways of Abeta generation and its regulation, and to allow evaluation of the diagnostic and therapeutic potential of the newly identified genes.
Specific Aim 1 proposes to identify gamma-secretase gene or genes affecting gamma- or beta-secretase activities.
Specific Aim 2 is to validate and characterize the genes identified and to understand how these gene products may affect betaAPP metabolism.

National Institute of Health (NIH)
National Institute on Aging (NIA)
Research Project (R01)
Project #
Application #
Study Section
Molecular, Cellular and Developmental Neurosciences 2 (MDCN)
Program Officer
Miller, Marilyn
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Sanford-Burnham Medical Research Institute
La Jolla
United States
Zip Code
Zhu, Bing; Jiang, LuLin; Huang, Timothy et al. (2017) ER-associated degradation regulates Alzheimer's amyloid pathology and memory function by modulating ?-secretase activity. Nat Commun 8:1472
Wu, Xi-Lin; PiƱa-Crespo, Juan; Zhang, Yun-Wu et al. (2017) Tau-mediated Neurodegeneration and Potential Implications in Diagnosis and Treatment of Alzheimer's Disease. Chin Med J (Engl) 130:2978-2990
Huang, Timothy Y; Zhao, Yingjun; Jiang, Lu-Lin et al. (2017) SORLA attenuates EphA4 signaling and amyloid ?-induced neurodegeneration. J Exp Med 214:3669-3685
Huang, Timothy Y; Zhao, Yingjun; Li, Xiaoguang et al. (2016) SNX27 and SORLA Interact to Reduce Amyloidogenic Subcellular Distribution and Processing of Amyloid Precursor Protein. J Neurosci 36:7996-8011
Wang, Chen; Niu, Mengxi; Zhou, Zehua et al. (2016) VPS35 regulates cell surface recycling and signaling of dopamine receptor D1. Neurobiol Aging 46:22-31
Zheng, Qiuyang; Huang, Timothy; Zhang, Lishan et al. (2016) Dysregulation of Ubiquitin-Proteasome System in Neurodegenerative Diseases. Front Aging Neurosci 8:303
Wang, Xin; Zhou, Ying; Wang, Jian et al. (2016) SNX27 Deletion Causes Hydrocephalus by Impairing Ependymal Cell Differentiation and Ciliogenesis. J Neurosci 36:12586-12597
Zhang, Cuilin; Shi, Zhun; Zhang, Lingzhi et al. (2016) Appoptosin interacts with mitochondrial outer-membrane fusion proteins and regulates mitochondrial morphology. J Cell Sci 129:994-1002
Feng, Tuancheng; Niu, Mengmeng; Ji, Chengxiang et al. (2016) SNX15 Regulates Cell Surface Recycling of APP and A? Generation. Mol Neurobiol 53:3690-3701
Barini, Erica; Antico, Odetta; Zhao, Yingjun et al. (2016) Metformin promotes tau aggregation and exacerbates abnormal behavior in a mouse model of tauopathy. Mol Neurodegener 11:16

Showing the most recent 10 out of 52 publications