Research Description

This laboratory is applying techniques of molecular biology and genetics to problems in medicine. Our major interests is non-insulin-dependent or Type 2 diabetes mellitus (NIDDM), a disorder or carbohydrate metabolism characterized by elevated blood glucose levels, which affects about 5% of the population in the United States. As with other common diseases of middle age such as cardiovascular disease and hypertension, genetic factors contribute to the development of NIDDM. Our working hypothesis is that a relatively small number, perhaps 5-10, of potentially identifiable major genes increase the risk of developing diabetes and that the individual's overall genetic background, together with environmental and lifestyle factors, influences the phenotypic expression of the major susceptibility genes.

In our genetic studies we are studying diabetes-prone families in which NIDDM has an early age-at-onset and a clear autosomal dominant mode of inheritance. These studies have resulted in the identification of two genes, one on chromosome 7 and another on chromosome 20, that are associated with early-onset NIDDM. The gene on chromosome 7 encodes the glycolic enzyme glucokinase which functions as the glucose sensor in the insulin-secreting cell to insulin so that higher blood glucose levels are required to stimulate insulin secretion. These mutations may be the cause of diabetes in 1-5% of all patients with NIDDM. They represent the most common cause of NIDDM identified to date.

Drawing on our understanding of the pathophysiology of NIDDM, we are also cloning and characterizing genes that might reasonably contribute to diabetes susceptibility. Since the pancreatic cell plays an important role in the pathogenesis of all forms of diabetes mellitus, we are particularly interested in studying genes in this cell type. We have partially sequenced over 1,200 randomly isolated cDNA clones from a human pancreatic islet cDNA library to determine the repertoire of genes expressed in normal adult human islets. About one-half of these clones represent known sequences and the remainder encode unknown proteins, some of which presumably endow the cell with its unique physiological properties. We are characterizing these novel gene products, as well as those encoding proteins of known function, in order to obtain an understanding of their roles in normal cell function and in the regulation of biosynthesis and secretion.

Finally, we have cloned the receptors for somatostatin and opioid peptides; this has led us into the area of neurobiology and the role of these receptors in the regulation of neuronal function.

Selected Publications

Exome sequencing and genetic testing for MODY.

Johansson S, Irgens H, Chudasama KK, Molnes J, Aerts J, Roque FS, Jonassen I, Levy S, Lima K, Knappskog PM, Bell GI, Molven A, Njølstad PR

(2012) PloS one 7(5):e38050 PMID:22662265 (Full Text)

An in vivo cis-regulatory screen at the type 2 diabetes associated TCF7L2 locus identifies multiple tissue-specific enhancers.

Savic D, Bell GI, Nobrega MA

(2012) PloS one 7(5):e36501 PMID:22590553 (Full Text)

Three Strikes and You're Cured.

Chong AS, Bell GI

(May 2012) Science translational medicine 4(133):133fs12 PMID:22572878

A genome-wide search for human non-insulin-dependent (type 2) diabetes genes reveals a major susceptibility locus on chromosome 2.

Hanis CL, Boerwinkle E, Chakraborty R, Ellsworth DL, Concannon P, Stirling B, Morrison VA, Wapelhorst B, Spielman RS, Gogolin-Ewens KJ, Shepard JM, Williams SR, Risch N, Hinds D, Iwasaki N, Ogata M, Omori Y, Petzold C, Rietzch H, Schröder HE, Schulze J, Cox NJ, Menzel S, Boriraj VV, Chen X, Lim LR, Lindner T, Mereu LE, Wang YQ, Xiang K, Yamagata K, Yang Y, Bell GI

(Jun 1996) Nature genetics 13(2):161-6 PMID:8640221

Mutations in the hepatocyte nuclear factor-1alpha gene in maturity-onset diabetes of the young (MODY3)

Yamagata K, Oda N, Kaisaki PJ, Menzel S, Furuta H, Vaxillaire M, Southam L, Cox RD, Lathrop GM, Boriraj VV, Chen X, Cox NJ, Oda Y, Yano H, Le Beau MM, Yamada S, Nishigori H, Takeda J, Fajans SS, Hattersley AT, Iwasaki N, Hansen T, Pedersen O, Polonsky KS, Bell GI

(Dec 1996) Nature 384(6608):455-8 PMID:8945470

Mutations in the hepatocyte nuclear factor-4alpha gene in maturity-onset diabetes of the young (MODY1)

Yamagata K, Furuta H, Oda N, Kaisaki PJ, Menzel S, Cox NJ, Fajans SS, Signorini S, Stoffel M, Bell GI

(Dec 1996) Nature 384(6608):458-60 PMID:8945471

Organization and partial sequence of the hepatocyte nuclear factor-4 alpha/MODY1 gene and identification of a missense mutation, R127W, in a Japanese family with MODY.

Furuta H, Iwasaki N, Oda N, Hinokio Y, Horikawa Y, Yamagata K, Yano N, Sugahiro J, Ogata M, Ohgawara H, Omori Y, Iwamoto Y, Bell GI

(Oct 1997) Diabetes 46(10):1652-7 PMID:9313765

Mutation in hepatocyte nuclear factor-1 beta gene (TCF2) associated with MODY.

Horikawa Y, Iwasaki N, Hara M, Furuta H, Hinokio Y, Cockburn BN, Lindner T, Yamagata K, Ogata M, Tomonaga O, Kuroki H, Kasahara T, Iwamoto Y, Bell GI

(Dec 1997) Nature genetics 17(4):384-5 PMID:9398836

Defective insulin secretion in hepatocyte nuclear factor 1alpha-deficient mice.

Pontoglio M, Sreenan S, Roe M, Pugh W, Ostrega D, Doyen A, Pick AJ, Baldwin A, Velho G, Froguel P, Levisetti M, Bonner-Weir S, Bell GI, Yaniv M, Polonsky KS

(May 1998) The Journal of clinical investigation 101(10):2215-22 PMID:9593777 (Full Text)

A second-generation screen of the human genome for susceptibility to insulin-dependent diabetes mellitus.

Concannon P, Gogolin-Ewens KJ, Hinds DA, Wapelhorst B, Morrison VA, Stirling B, Mitra M, Farmer J, Williams SR, Cox NJ, Bell GI, Risch N, Spielman RS

(Jul 1998) Nature genetics 19(3):292-6 PMID:9662408

Defective pancreatic beta-cell glycolytic signaling in hepatocyte nuclear factor-1alpha-deficient mice.

Dukes ID, Sreenan S, Roe MW, Levisetti M, Zhou YP, Ostrega D, Bell GI, Pontoglio M, Yaniv M, Philipson L, Polonsky KS

(Sep 1998) The Journal of biological chemistry 273(38):24457-64 PMID:9733737