Nuclear factor 1 B-type is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
that in humans is encoded by the ''NFIB''
gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
.
NFIB haploinsufficiency is also associated with intellectual disability and macrocephaly, as are NFIA and NFIX.
Embryonic Development
The NFIB gene is a part of the NFI gene complex that includes three other genes (
NFIA
Nuclear factor 1 A-type is a protein that in humans is encoded by the ''NFIA'' gene.
Function
Nuclear factor I (NFI) proteins constitute a family of dimeric DNA-binding proteins with similar, and possibly identical, DNA-binding specificity. T ...
,
NFIC and
NFIX
Nuclear factor 1 X-type is a protein that in humans is encoded by the ''NFIX'' gene. NFI-X3, a splice variant of NFIX, regulates Glial fibrillary acidic protein and YKL-40 in astrocytes.
Interactions
Nfix has been shown to interact with SKI p ...
).
The NFIB gene is a protein coding gene that also serves as a
transcription factor
In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence. The f ...
.
This gene is essential in embryonic development and it works together with its gene complex to initiate tissue
differentiation in the fetus. NFIB has the highest concentrations in the lung,
skeletal muscle and heart but is also found in the areas of the developing liver, kidneys and brain.
Through knockout experiments, researchers found that mice without the NFIB gene have severely underdeveloped lungs.
This mutation does not seem to cause spontaneous abortions because in utero the fetus does not use its lungs for
respiration
Respiration may refer to:
Biology
* Cellular respiration, the process in which nutrients are converted into useful energy in a cell
** Anaerobic respiration, cellular respiration without oxygen
** Maintenance respiration, the amount of cellul ...
. However, this becomes lethal once the fetus is born and has to take its first breath. It is thought that NFIB plays a role in down regulating the transcription factors
TGF-β1 and
''Shh'' in normal gestation because they remained high in knockout experiments.
The absence of NFIB also leads to insufficient amounts of
surfactant being produced which is one reason why the mice cannot breathe once it is born.
The knockout experiments demonstrated that NFIB has a significant role in fore-brain development. NFIB is typically found in
pontine nuclei
Pontine may refer to:
* Having to do with the pons, a structure located in the brain stem (from ''pons'', "bridge")
* Pontine Marshes, a region of Italy near Rome
* Pontine Islands
The Pontine Islands (, also ; it, Isole Ponziane ) are an ar ...
of the
CNS, the
cerebral cortex
The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consistin ...
and the white matter of the brain and without NFIB these areas are dramatically affected.
Absence of one copy is associated with
macrocephaly
Macrocephaly is a condition in which circumference of the human head is abnormally large. It may be pathological or harmless, and can be a familial genetic characteristic. People diagnosed with macrocephaly will receive further medical tests to ...
and intellectual disability. This associated was confirmed in mouse modelswhere deletion of one copy resulted in enlargement of the brain while preserving its overall organisation.
References
Further reading
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External links
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Transcription factors
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