As blood sugars rise during development of pre-diabetes, cardiovascular consequences such as stroke, myocardial infarction and mortality are already increasing by 2-4 fold, yet there remains a fundamental gap in understanding how and why pre-diabetes develops. The inability to predict, within a population with similar risk factors for diabetes, which are more susceptible than others represents an important problem because, until it is resolved, strategies to prevent/treat pre-diabetes/dysglycemia will remain largely untenable. Strategies to halt dysglycemia require a multi-pronged approach, since the pathophysiology involves both peripheral insulin resistance and pancreatic ? cell dysfunction. Factors that are linked to failures in both processes are in-demand for therapeutic focus;we have identified the p21-activated kinase, PAK1, as such a factor. Further, losses of PAK1 abundance are associated with diabetes and obesity in human islets and human skeletal muscle, tissues that are key to regulating insulin release and insulin sensitivity, respectively. Thus, the long-term goal is to understand how the PAK1 pathways in these tissues can be manipulated to treat/prevent pre-diabetes, ultimately halting progression to frank diabetes. The objective of this particular application is to discriminate how PAK1 functions (PAK1 plays roles in signaling as well as scaffolding in other cell types) in ? cell insulin secretion and skeletal muscle insulin action in vivo and at the molecular level. PAK1 pathways are known in other cell types to evoke dynamic actin cytoskeleton changes, and preliminary data suggest such changes to be part of insulin release and glucose clearance mechanisms. Preliminary data show that classic whole-body PAK1 knockout mice fed a 42% fat diet for just 10 weeks develop fasting hyperglycemia, insulin insufficiency and severe glucose intolerance. Additionally, restoration of PAK1 abundance or signaling in islet ? cells restores insulin secretion and reduces ? cell apoptosis. These findings give rise to the central hypotheses, that a) PAK1 is a central regulator of glucose homeostasis via functions in actin remodeling-regulated exocytosis events in both ? cells and skeletal muscle cells, and b) that PAK1 deficiency culminates in heightened susceptibility to glycemic dysregulation and pre-diabetes. The rationale for the proposed research is that once it is known how PAK1 is needed in ? cells versus skeletal muscle cells, that the PAK1 pathways can be manipulated to avert pre-diabetic dysglycemia. This hypothesis will be tested in two Specific Aims: 1) Delineate the mechanism(s) for PAK1 actions in ? cell function and survival, 2) Elucidate the mechanism(s) by which PAK1 promotes skeletal muscle insulin sensitivity.
Aims will be accomplished using innovative inducible ? cell and skeletal muscle PAK1 knockout mice and live-cell imaging biosensors with biochemical assays, and relevant human islet and muscle tissues. Results of these interrogations are expected to positively impact efforts to ameliorate pre-diabetes, because the identified effectors and mechanisms are highly likely to provide new therapeutic targets.

Public Health Relevance

The proposed research is relevant to public health because the discovery of factors that predict conversion to dysglycemia is expected to positively impact efforts to ameliorate pre-diabetes, because the identified mechanisms are highly likely to provide new therapeutic targets. Thus the proposed research is relevant to the mission of the NIDDK because it will develop fundamental knowledge that will help to reduce the burdens of diabetes.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
1R01DK102233-01A1
Application #
8815580
Study Section
Cellular Aspects of Diabetes and Obesity Study Section (CADO)
Program Officer
Silva, Corinne M
Project Start
2014-09-12
Project End
2018-07-31
Budget Start
2014-09-12
Budget End
2015-07-31
Support Year
1
Fiscal Year
2014
Total Cost
$347,808
Indirect Cost
$122,808
Name
Indiana University-Purdue University at Indianapolis
Department
Pediatrics
Type
Schools of Medicine
DUNS #
603007902
City
Indianapolis
State
IN
Country
United States
Zip Code
46202
Aslamy, Arianne; Oh, Eunjin; Olson, Erika M et al. (2018) Doc2b Protects ?-Cells Against Inflammatory Damage and Enhances Function. Diabetes 67:1332-1344
Salunkhe, Vishal A; Veluthakal, Rajakrishnan; Kahn, Steven E et al. (2018) Novel approaches to restore beta cell function in prediabetes and type 2 diabetes. Diabetologia 61:1895-1901
Oh, Eunjin; Ahn, Miwon; Afelik, Solomon et al. (2018) Syntaxin 4 Expression in Pancreatic ?-Cells Promotes Islet Function and Protects Functional ?-Cell Mass. Diabetes 67:2626-2639
Veluthakal, Rajakrishnan; Chepurny, Oleg G; Leech, Colin A et al. (2018) Restoration of Glucose-Stimulated Cdc42-Pak1 Activation and Insulin Secretion by a Selective Epac Activator in Type 2 Diabetic Human Islets. Diabetes 67:1999-2011
Aslamy, Arianne; Oh, Eunjin; Ahn, Miwon et al. (2018) Exocytosis Protein DOC2B as a Biomarker of Type 1 Diabetes. J Clin Endocrinol Metab 103:1966-1976
Tunduguru, Ragadeepthi; Thurmond, Debbie C (2017) Promoting Glucose Transporter-4 Vesicle Trafficking along Cytoskeletal Tracks: PAK-Ing Them Out. Front Endocrinol (Lausanne) 8:329
Tunduguru, Ragadeepthi; Zhang, Jing; Aslamy, Arianne et al. (2017) The actin-related p41ARC subunit contributes to p21-activated kinase-1 (PAK1)-mediated glucose uptake into skeletal muscle cells. J Biol Chem 292:19034-19043
Aslamy, Arianne; Thurmond, Debbie C (2017) Exocytosis proteins as novel targets for diabetes prevention and/or remediation? Am J Physiol Regul Integr Comp Physiol 312:R739-R752
Ocaña, Gail J; Pérez, Liliana; Guindon, Lynette et al. (2017) Inflammatory stress of pancreatic beta cells drives release of extracellular heat-shock protein 90?. Immunology 151:198-210
Ahn, Miwon; Yoder, Stephanie M; Wang, Zhanxiang et al. (2016) The p21-activated kinase (PAK1) is involved in diet-induced beta cell mass expansion and survival in mice and human islets. Diabetologia 59:2145-55

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