Gene Description

Symbol:  Nfic

Gene:  nuclear factor I/C (nuclear factor 1 C-type)

Chromosome:  10

Background Strain:  Mixed

Strain Development:  This strain is a targeted mutation in which the Nfic gene function has been disrupted. E14-1 ES cells were injected into C57BL/6 blastocysts and chimeric males were crossed to C57BL/6, Black Swiss, and 129S6 females.

Other Strain Names:  Nfic^-/-

Summary of Phenotype

Results of this report are primarily descriptive and represent analysis of 2 mutant mice. They should therefore be interpreted with caution and as preliminary observation-generating data. The tooth phenotype of these mice has been thoroughly charcterized by Steele-Perkins et. al. (see literature review).

On gross necropsy examination, one homozygous mutant was runted (bw = 9.1g compared to 21.7g for wild type). For this report the runted mutant is designated STOCK-Nfic^tm (C), the non-runted mutant is designated STOCK-Nfic^tm (A), and the wild type is designated STOCK littermate (B).

Both homozygous mutants had no mandibular incisors. Maxillary incisors were overgrown and/or fractured. Histologically, the mandibular incisor roots were absent and replaced by connective tissue, mature boney spicules and vascular sinuses. The only remnant of tooth tissue was a circular acinus of cells morphologically reminiscent of ameloblasts on one side of the mandible of the non-runted mutant. The maxillary incisors of both mutants contained all components of normal teeth, however there were patchy areas of vacuolation where vacuoles contained entrapped dead ameloblasts; these areas disrupted the normal radial deposition of enamel and were present near the ameloblast border. The molar teeth of both mutants contained all components of normal teeth, however, the roots were short and irregular as compared to the control mouse; these molar teeth were embedded in disorganized connective tissue which contained fragments of disorganized enamel.

Additional musculoskeletal defects were noted in the growth plates of the stifle and costochondral junctions. In both mutants, the growth plates had irregular, minimal to absent zones of calcification. The runted mutant also had a moderate to marked reduction in bone marrow hematopoietic cell density, suggestive of altered hematopoiesis. These findings may be related to the gene mutation or may be the result of runting or malnutrition secondary to the tooth defects. A similar growth plate compression and altered hematopoiesis has been described in mice with targeted mutations in collagen X.

Tissues from the runted mutant were in general underdeveloped. This was evident in both organ weight and histologic analysis. The significance of these findings is unknown, but they most likely represent a result rather that a cause of the runting phenotype.

Summary - Gross Findings

One homozygous mutant was runted and had scant body fat. Both homozygous mutants had no lower incisors. Both upper incisors of the runted mutant (STOCK-Nfic^tm [C]) were overgrown. One incisor of the the non-runted mutant (STOCK-Nfic^tm [A]) was overgrown; the other was fractured.

Organ/Body Weights

	STOCK-Nfictm (A)	STOCK littermate (B)	STOCK-Nfictm (C)
adrenal glands	0.0099g	0.0094g	0.0040g
body weight	19.1g	21.7g	9.1g
brain	0.4730g	0.4724g	0.4161g
heart	0.0985g	0.1066g	0.0500g
kidney (left)	0.1382g	0.1557g	0.0697g
liver	0.7654g	0.9872g	0.3900g
lungs	0.1477g	0.2193g	0.0969g
ovary (left)	0.0050g	0.0079g	0.0011g
spleen	0.0462g	0.0658g	0.0126g

Summary - Histology

Histologically, the mandibular incisor roots of both mutants were absent and replaced by connective tissue, mature boney spicules and vascular sinuses. The only remnant of tooth tissue was a circular acinus of cells morphologically reminiscent of ameloblasts on one side of the mandible of the non-runted mutant. The maxillary incisors contained all components of normal teeth, however there were patchy areas of vacuolation where vacuoles contained entrapped dead ameloblasts; these areas disrupted the normal radial deposition of enamel and were present near the ameloblast border. The molar teeth of both mutants contained all components of normal teeth, however, the roots were short and irregular as compared to the control mouse; these molar teeth were embedded in disorganized connective tissue which contained fragments of disorganized enamel.

Additional musculoskeletal defects were noted in the growth plates of the stifle and costochondral junctions. In the runted mutant (STOCK-Nfic^tm [C]), the growth plates had irregular, minimal to absent zones of calcification and there was moderate to marked reduction in bone marrow hematopoietic cell density, suggestive of altered hematopoiesis.

Tissues from the runted mutant (STOCK-Nfic^tm [C]) were in general underdeveloped. This was evident in both organ weight and histologic analysis.

Other findings that may warrant additional pursuit include:

1) The runted mutant (STOCK-Nfic^tm [C]) had altered brown fat morphology characterized by the presence of large coalesced lipid vacuoles. The significance of this finding is unknown; these larger confluent vacuolated cells may represent quiescent cells. Similar alterations in brown fat morphology have been described in IFN-treated mice, mice carrying a transgene encoding glycerol 3-phosphate dehydrogenase and obese Zucker rats.

2) The runted mutant (STOCK-Nfic^tm [C]) had an apparent increase in ovarian follicle apoptosis. This finding should be interpreted very cautiously as apoptosis is a normal component of follicular atresia.

3) A lack of sebaceous gland development was evident in the clitoral (runted mutant - STOCK-Nfic^tm [C]) and cutaneous (both mutants) sebaceous glands.

4) The runted mutant (STOCK-Nfic^tm [C]) had a dysplastic adrenal medulla.

Other findings of unknown significance were also seen , however, these are not believed to be related to the gene mutation:

1) The mid-sized mutant (STOCK-Nfic^tm [A]) had retinal degeneration.

2) The wild type mouse (STOCK littermate [B]) had a rounded heart; no significant histologic lesions were found.

Phenotypic Abnormalities - Histology
STOCK-Nfic^tm (unofficial nomenclature)

Organ	Lesion	Sex	Age	# Affected	Image(s)
incisor teeth	incisor agenesis	F	2m	2/2
molar teeth	molar dysplasia	F	2m	2/2

Click on lesion for full description. Click on image for larger view.

Other Abnormalities - Histology
STOCK-Nfic^tm (unofficial nomenclature)

Other abnormalities include lesions seen in the mutant(s) that were not seen in the control animal(s).
The significance and relation to genotype is unknown.

Organ	Lesion	Sex	Age	# Affected	Image(s)
brown fat	dysplasia	F	2m	1/2
stifle	epiphyseal hypoplasia	F	2m	1/2
costrochondral junction	growth plate dysplasia	F	2m	1/2
clitoral gland	underdeveloped	F	2m	1/2

Click on lesion for full description. Click on image for larger view.

Complete Data - Histology

(Click on lesion for full description.)

	STOCK-Nfictm (A)	STOCK littermate (B)	STOCK-Nfictm (C)
adrenal gland(s)
corticomedullary vacuolation	-	+	-
medullary dysplasia	-	-	+
aorta
no lesions	-	-	-
bone marrow
decreased hematopoesis	-	-	+
brown fat
dysplasia	-	-	+
cecum
no lesions	-	-	-
cerebellum
no lesions	-	-	-
cerebrum
focal mineralization	+	-	-
normal tissue	+	+	+
cervix
no lesions	-	-	-
clitoral gland
tissue not found	+	-	-
underdeveloped	-	-	+
costrochondral junction
growth plate dysplasia	-	-	+
diaphragm
mulinucleated myofibers	-	-	+
distal colon
no lesions	-	-	-
duodenum
no lesions	-	-	-
exorbital /infraorbital glands
no lesions	-	-	-
eye
retinal degeneration	+	-	-
femoral bone marrow
no lesions	-	-	-
femur
no lesions	-	-	-
gallbladder
no lesions		-
Harderian gland
decreased lipid content	-	-	+
heart
very mild lipidosis	-	+	+
ileum
no lesions	-	-	-
incisor teeth
incisor agenesis	+	-	+
inner ear
no lesions	-	-	-
jejunum
no lesions	-	-	-
kidneys
no lesions	-	-	-
liver
portal mononuclear cell infiltrate	+	-	-
hematopoiesis	+	-	-
microabscesses	-	+	-
lung
peribronchiolar lymphoid infiltrates	-	+	-
major bile duct
no lesions	-		-
mammary gland
immature mammary gland	+	+	+
mandibular lymph node(s)
no lesions	-	-	-
mesenteric lymph node
medullary plasmacytosis	+	-	-
molar teeth
molar dysplasia	+	-	+
nasal cavity
no lesions	+	+	+
ovary
delayed development	+	-	-
normal ovary	-	+	-
pancreas
no lesions	-	-	-
parathyroid gland
tissue not found	+	+	-
parotid salivary glands
vacuolated acinar cells	-	-	+
pituitary gland
tissue not found	-	+	-
proximal colon
no lesions	-	-	-
quadriceps muscle
mulinucleated myofibers	-	-	+
sciatic nerve
no lesions	-	-	-
skin
sebaceous hypoplasia	-	+	+
spinal cord
no lesions	-	-	-
spleen
hypoplasia	-	-	+
stifle
epiphyseal hypoplasia	-	-	+
stomach
no lesions	-	-	-
sublingual salivary gland
no lesions	-	-	-
submand. salivary glands
no lesions	-	-	-
thyroid gland
no lesions	-	-	-
tongue
no lesions	-	-	-
trachea
no lesions	-	-	-
urinary bladder
underdeveloped bladder	-	-	+
uterus
metestrus uterus	+	-	-
diestrus / proestrus uterus	-	+	-
non-cycling uterus	-	-	+
vagina
metestrus vagina	+	-	-
diestrus/proestrus vagina	-	+	-
non-cycling vagina	-	-	+

Comments:  Multiple sections of the following tissues were examined:
brain - 4 coronal sections
head (nasal cavity, teeth, ear structures) - 8 sections
liver - sections of 3 lobes
lung - sections of 4 lobes
spinal column - 14 cross sections
heart - 3 cross sections
kidneys - one section of each kidney

In addition, 2-8 serial sections were prepared for several organs including the brain, head and stifle.

The gallbladder was not present on sections from both mutants; the major bile ducts were examined and found to have no significant lesions.

Summary - Behavioral Testing

A simple series of behavior tests was performed. All mice exhibited exploratory behavior, however the runted mutant (STOCK-Nfic^tm [C]) was less active (hid in bedding) in the presence of the other two mice. No differences were noted when mice were placed individually in a clean cage (normal exploration). No differences were noted in vertical pole test performance (a measure of motor coordination and balance), or grip strength. The runted mutant (STOCK-Nfic^tm [C]) displayed intermittent hind and forelimb clasping, the non-runted mutant (STOCK-Nfic^tm [A]) displayed intermittent hind limb clasping and the control mouse (STOCK littermate [B]) displayed rare hind limb clasping when suspended by the tail. The significance of these findings is unknown, however we have observed clasping behavior in mice with early experimentally induced neurologic disease (experimental allergic encephalomyelitis). The influence of the 129 background should also be considered.

Summary - Clinical Chemistry

No genotype associated abnormalties were observed in clinical chemistry analysis.

Complete Data - Clinical Chemistry

	STOCK-Nfictm (A)	STOCK littermate (B)	STOCK-Nfictm (C)
Glucose (mg/dL)	144	206
Urea Nitrogen (mg/dL)	35	21	37
Creatinine (mg/dL)	0.3	0.2
Sodium (mmol/L)	149	146
Potassium (mmol/L)	4.6	5.9
Chloride (mmol/L)	119	117
Total Protein (g/dL)	5.2	5.3
Albumin (g/dL)	2.3	2.2
Globulin (g/dL)	3	3.1
Calcium (mg/dL)	9.8	10
Phosphorus (mg/dL)	6.3	7
Cholesterol (mg/dL)	86	114
Cholesterol (mg/dL)	86	114
Total Bili (mg/dL)	0.5	0.8
ALT (U/L)	45	16	56
ALP (U/L)	160	131

Comments:  Insufficient blood was obtained from the runted to mutant to run a complete chemistry panel.

Summary - Hematology

No genotype associated hematologic abnormalties were observed.

Complete Data - Hematology

	STOCK-Nfictm (A)	STOCK littermate (B)	STOCK-Nfictm (C)
Leukocytes
WBC (x10³/μL)	12.98	10.34	8.40
Manual differential data (smear submitted)
Segmented Neutrophils (%)	14.06	14.13	25.69
Lymphocytes (%)	79.53	80.97	62.98
Monocytes (%)	6.09	4.18	6.79
Eosinophils (%)	0.30	0.58	3.29
Basophils (%)	0.03	0.13	1.24
Absolute leukocytes numbers calculated from manual differential
Segmented Neutrophils (x10³/μL)	1.82	1.46	2.16
Lymphocytes (x10³/μL)	10.32	8.37	5.29
Monocytes (x10³/μL)	0.79	0.43	0.57
Eosinophils (x10³/μL)	0.04	0.06	0.28
Basophils (x10³/μL)	0.00	0.01	0.10
Red blood cell parameters
RBC (M/μL)	8.90	10.30	11.74
Hemoglobin (g/dL)	12.00	15.50	15.50
Hematocrit (%)	41.90	62.80	62.90
MCV (fL)	47.10	61.00	53.60
MCH (pg)	13.50	15.00	13.20
MCHC (g/dL)	28.60	24.70	24.60
Platelet parameters
Platelets (x10³/μL)	560.00	560.00	500.00
MPV (fL)	4.90	4.10	4.70

Literature Review

• Steele-Perkins G, Butz KG, Lyons GE, Zeichner-David M, Kim HJ, Cho MI, Gronostajski RM
  
  Essential role for NFI-C/CTF transcription-replication factor in tooth root development. Mol Cell Biol. 2003 Feb;23(3):1075-84.