Jack L. Leonard, Ph.D.

Academic Role: Professor
Faculty Appointment(s) and Affiliations:

     School of Medicine
        Microbiology and Physiological Systems
     Graduate School of Biomedical Sciences   
        Interdisciplinary Graduate Program


Jack L. Leonard, Ph.D.

The focus of this laboratory is the characterization of cellular and molecular events that mediate thyroid hormone action in the brain. Current studies include:  cloning and sequencing of the plasma membrane-bound enzyme that bioactivates thyroid hormone; determination of the subunit structure and physiochemical properties of the enzyme polypeptide; characterization of the internalization, sorting and degradation pathway(s) of short-lived membrane proteins in the brain; sequencing of a 55 kDa actin-binding protein whose interactions with actin are hormonally regulated; characterization of the isotypes of erb-a gene products present in cultured cerebrocortical astrocytes; identification of cyclic nucleotide-induced gene products in cultured glial cells using substraction cloning; and determination of the developmental programming of cytoskeletal and integrin gene products in cultured fetal brain cells.


This is a GFP expressing neuron.



Recent Publications

Cheng SY, Leonard JL, Davis PJ.  Molecular aspects of thyroid hormone actions.  Endocr Rev 2010; 31:139-70.

Farwell AP, Leonard JL.  Effect of methyl iodide on deiodinase activity. Inhal Toxicol 2009; 21:497-504.

Leonard JL.  Non-genomic actions of thyroid hormone in brain development.  Steroids 2008; 73:1008-12.

Davis PJ, Leonard JL, Davis FB.  Mechanisms of nongenomic actions of thyroid hormone. Front Neuroendocrinol 2008; 29:211-8.

Simpson GI, Leonard DM, Leonard JL. VIdentification of the key residues responsible for the assembly of selenodeiodinases.  J Biol Chem 2006; 281:14615-21.

Farwell AP, Dubord-Tomasetti SA, Pietrzykowski AZ, Leonard JL.  Dynamic nongenomic actions of thyroid hormone in the developing rat brain.  Endocrinology 2006; 147:2567-74.

Alkemade A, Friesema EC, Unmehopa UA, Fabriek BO, Kuiper GG, Leonard JL, Wiersinga WM, Swaab DF, Visser TJ, Fliers E.  Neuroanatomical pathways for thyroid hormone feedback in the human hypothalamus.  J Clin Endocrinol Metab 2005; 90:4322-34.

Leonard JL, Simpson G, Leonard DM.  Characterization of the protein dimerization domain responsible for assembly of functional selenodeiodinases.  J Biol Chem 2005; 280:11093-100.

Farwell AP, Dubord-Tomasetti SA, Pietrzykowski AZ, Stachelek SJ, Leonard JL.  Regulation of cerebellar neuronal migration and neurite outgrowth by thyroxine and 3,3',5'-triiodothyronine. Brain Res Dev Brain Res 2005; 154:121-35.

Dobson JG, Fray J, Leonard JL, Pratt RE.  Molecular mechanisms of reduced beta-adrenergic signaling in the aged heart as revealed by genomic profiling.  Physiol Genomics 2003; 15:142-7.

Diano S, Leonard JL, Meli R, Esposito E, Schiavo L.  Hypothalamic type II iodothyronine deiodinase: a light and electron microscopic study.  Brain Res 2003; 976:130-4.

Verhoelst CH, Vandenborne K, Severi T, Bakker O, Zandieh Doulabi B, Leonard JL, Kühn ER, van der Geyten S, Darras VM.  Specific detection of type III iodothyronine deiodinase protein in chicken cerebellar purkinje cells.  Endocrinology 2002; 143:2700-7.

Stachelek SJ, Tuft RA, Lifschitz LM, Leonard DM, Farwell AP, Leonard JL.  Real-time visualization of processive myosin 5a-mediated vesicle movement in living astrocytes.  J Biol Chem 2001; 276:35652-9.

Vacanti MP, Leonard JL, Dore B, Bonassar LJ, Cao Y, Stachelek SJ, Vacanti JP, O'Connell F, Yu CS, Farwell AP, Vacanti CA.  Tissue-engineered spinal cord.  Transplant Proc 2001; 33:592-8.

Leonard JL, Visser TJ, Leonard DM.  Characterization of the subunit structure of the catalytically active type I iodothyronine deiodinase.  J Biol Chem 2001; 276:2600-7.

Stachelek SJ, Kowalik TF, Farwell AP, Leonard JL.  Myosin V plays an essential role in the thyroid hormone-dependent endocytosis of type II iodothyronine 5'-deiodinase.  J Biol Chem 2000; 275:31701-7.

Leonard DM, Stachelek SJ, Safran M, Farwell AP, Kowalik TF, Leonard JL.  Cloning, expression, and functional characterization of the substrate binding subunit of rat type II iodothyronine 5'-deiodinase.  J Biol Chem 2000; 275:25194-201.

Dowling AL, Martz GU, Leonard JL, Zoeller RT.  Acute changes in maternal thyroid hormone induce rapid and transient changes in gene expression in fetal rat brain.  J Neurosci 2000; 20:2255-65.

Sanders JP, Van der Geyten S, Kaptein E, Darras VM, Kühn ER, Leonard JL, Visser TJ. Cloning and characterization of type III iodothyronine deiodinase from the fish Oreochromis niloticus. Endocrinology 1999; 140:3666-73.

Leonard JL, Leonard DM, Safran M, Wu R, Zapp ML, Farwell AP.  The mammalian homolog of the frog type II selenodeiodinase does not encode a functional enzyme in the rat. Endocrinology 1999; 140:2206-15.

Shen Q, Wu R, Leonard JL, Newburger PE.  Identification and molecular cloning of a human selenocysteine insertion sequence-binding protein.  A bifunctional role for DNA-binding protein B.  J Biol Chem 1998; 273:5443-6.



Academic Background

Ph.D. University of Caifornia Berkeley, 1976



Telephone:  508-856-6687
EMail:   Jack.Leonard@umassmed.edu

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