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Felicia V.
Nowak, M.D., Ph.D.
Associate Professor of Molecular
Endocrinology
Department of Biomedical Sciences
nowak@ohiou.edu
Academic & Research Center 202E
740-593-2223 |
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Introduction to Neuropeptides |
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The
organization and ultimate normal function of the
adult mammalian brain reflects the orchestration of
extensive cellular migration, selective survival and
differentiation during development. Many neuronal
cells have the potential to display a seemingly
endless array of phenotypes and thus retain a degree
of functional plasticity throughout life.
Understanding the roles of individual gene products,
including neuropeptides, in this process will
enhance our understanding of normal brain
development. It will also expand our capacity to
manipulate brain function in disease states.
Many neuropeptides are widely expressed and some of
them exhibit multiple functions. Often the specific
function observed is a result of the timing and
location of expression. Hormones can also profoundly
affect gene expression, incuding neuropeptide gene
expression. |
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| The
preoptic regulatory factors, PORF-1 and PORF-2 |
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laboratory is focused on studying the functions and
mechanisms of action of two neuropeptide genes, the
preoptic regulatory factors, PORF-1 and PORF-2.
These genes give rise to two unique peptides which
are expressed in the mammalian brain and whose
expression is regulated by age, gender and hormonal
status in a brain region dependent manner. Areas of
special interest include the hypothalamus, a major
regulatory region for neuroendocrine and metabolic
functions and the hippocampus, a key area in
learning and memory. |
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| Brain
Development and Neurogenesis |
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PORF-1
and PORF-2 may be involved in gender specific
development and function of the hypothalamus and
hippocampus. Like many neuropeptide factors that are
expressed highly during development, PORF-2 and
PORF-2 may also play a role in adult neurogenesis.
Neurogenic factors may play an important role in
brain recovery from injury and insults such as
strokes. They also have pharmaceutical potential in
the treatment of neurodegenerative diseases such as
Alzheimer's and Parkinson's Diseases.
Figure One.
Northern blot analysis of PORF-1 and PORF-2
messenger RNA in rat hypothalamus during
development. (From FV Nowak and AC Gore.
Perinatal Developmental Changes in Expression of
the Neurpeptide Genes Preoptid Regulatory
Factor-1 and Factor-2, Neuropeptide Y and GnRH
in Rat Hypothalamus. Journal of Neuroendocrinol
11:951-958, 1999.) E18-19 = embryonic day 18 to
19, PO = date of birth, P5, P10, P15 = postnatal
days 5, 10, and 15, F = female, M = male.
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PORF-1 May be a Transcription Factor |
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Based on
its structure, PORF-1 is thought to be a
transcription factor. One of the genes that it
regulates may be the type 2 iodothyronine deiodinase
(dio2). Dio2 is a key enzyme in the conversion of
thyroid hormone to its active form in the central
nervous system. Thyroid hormone activiation is
essential for normal motor and cognitive function
and for CNS development. We are currently
investigating the role of PORF-1 in the regulation
of this and other genes. The experimental approaches
include recombinant protein expression, DNA binding
assays and subcellular localization of PORF-1.
Figure Two.
Structure of PORF-1. (From FV Nowak, Expression
and Characterization of the Preoptic Regulatory
Factor-1 and -2 Peptides. Regulatory Peptides
115:179-185, 2003.) TAD = transcription
activation domain, LZ = leucine zipper, DBD =
DNA binding domain, nls = nuclear localization
signal, Se-C = selenocysteine.
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PORF-2 is a Growth Factor |
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We
believe that PORF-2 is a growth factor. Several
lines of evidence support this hypothesis. PORF-2 is
expressed in several cell types that are rapidly
dividing, including skin fibroblasts, immature germ
cells in the testes and the placental growth cone.
In addition, cells which are transfected and express
high levels of PORF-2 show an increase in cell
number as well as an increase in thymidine
incorporation, indicating that DNA synthesis and
cell division are stimulated.
Figure Three.
Structure of PORF-2. (From FV Nowak, Expression
and Characterization of the Preoptic Regulatory
Factor-1 and -2 Peptides. Regulatory Peptides
115:179-185, 2003.) Residues shown in bold are
potential phosphorylation sites for protein
kinase C (T52) and casein kinase 2 (T22 and
S69).
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work in the lab includes the screening of a mouse
genomic library to identify PORF-2 clones. These
clones will be used to make constructs to engineer
null or so-called "knock-out" mice. The knock out
mice can be used to assess the effects of PORF-2 on
growth and development, including brain development.
We may see effects in rapidly dividing cells, such
as skin and intestines. We also may see effects on
fertility (germ cell expression) and fecundity
(placental growth cone). |
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Expression of PORF-1 and PORF-2 are Modified by a
Variety of Hormones |
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on, it was shown that PORF-1 and PORF-2 expression
is altered by gonadal hormones, including estrogen
and progesterone in females and probably
testosterone in males. More recently it has been
demonstrated that hydrocortisone and insulin also
affect the expression of PORF-1 and PORF-2 in
cultured cells. Experiments are ongoing to further
quantify and characterize these effects, including
the intracellular signalling pathways that are
involved.
Current work in the laboratory also involves DNA
sequence analysis of the 5' promoter and regulatory
regions in the porf-1 and porf-2 genes
responsible for the observed hormonal effects.
Figure Four.
DNA sequence of a segment of the porf-1
gene.
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Ohio University
Heritage
College of Osteopathic Medicine
Irvine Hall, Athens, Ohio 45701
740-593-2530 740-597-2778 fax |
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