Evidence That Up-Regulation of MicroRNA-29 Contributes to Postnatal Body Growth Deceleration.

Body growth is rapid in infancy but subsequently slows and eventually ceases due to a progressive decline in cell proliferation that occurs simultaneously in multiple organs. We previously showed that this decline in proliferation is driven in part by postnatal down-regulation of a large set of growth-promoting genes in multiple organs. We hypothesized that this growth-limiting genetic program is orchestrated by microRNAs (miRNAs). Bioinformatic analysis identified target sequences of the miR-29 family of miRNAs to be overrepresented in age-down-regulated genes. Concomitantly, expression microarray analysis in mouse kidney and lung showed that all members of the miR-29 family, miR-29a, -b, and -c, were strongly up-regulated from 1 to 6 weeks of age. Real-time PCR confirmed that miR-29a, -b, and -c were up-regulated with age in liver, kidney, lung, and heart, and their expression levels were higher in hepatocytes isolated from 5-week-old mice than in hepatocytes from embryonic mouse liver at embryonic day 16.5. We next focused on 3 predicted miR-29 target genes (Igf1, Imp1, and Mest), all of which are growth-promoting. A 3'-untranslated region containing the predicted target sequences from each gene was placed individually in a luciferase reporter construct. Transfection of miR-29 mimics suppressed luciferase gene activity for all 3 genes, and this suppression was diminished by mutating the target sequences, suggesting that these genes are indeed regulated by miR-29. Taken together, the findings suggest that up-regulation of miR-29 during juvenile life drives the down-regulation of multiple growth-promoting genes, thus contributing to physiological slowing and eventual cessation of body growth.

Evolutionary conservation and modulation of a juvenile growth-regulating genetic program.

Body size varies enormously among mammalian species. In small mammals, body growth is typically suppressed rapidly, within weeks, whereas in large mammals, growth is suppressed slowly, over years, allowing for a greater adult size. We recently reported evidence that body growth suppression in rodents is caused in part by a juvenile genetic program that occurs in multiple tissues simultaneously and involves the downregulation of a large set of growth-promoting genes. We hypothesized that this genetic program is conserved in large mammals but that its time course is evolutionarily modulated such that it plays out more slowly, allowing for more prolonged growth. Consistent with this hypothesis, using expression microarray analysis, we identified a set of genes that are downregulated with age in both juvenile sheep kidney and lung. This overlapping gene set was enriched for genes involved in cell proliferation and growth and showed striking similarity to a set of genes downregulated with age in multiple organs of the juvenile mouse and rat, indicating that the multiorgan juvenile genetic program previously described in rodents has been conserved in the 80 million years since sheep and rodents diverged in evolution. Using microarray and real-time PCR, we found that the pace of this program was most rapid in mice, more gradual in rats, and most gradual in sheep. These findings support the hypothesis that a growth-regulating genetic program is conserved among mammalian species but that its pace is modulated to allow more prolonged growth and therefore greater adult body size in larger mammals.

Type 1 diabetes mellitus in a patient with homozygous sickle cell anemia.

In children with sickle cell disease, reports of type 1 diabetes mellitus (T1D) are extremely rare. Several studies failed to show the co-existence of the two conditions. In the few cases reported, the diagnosis has been made solely based on the clinical presentation. Here we report the case of an adolescent with sickle cell anemia who presented with hyperglycemia and positive T1D-specific auto-antibodies.

Diabetic ketoacidosis with cerebral hemorrhage and alpha coma in an adolescent female.

BACKGROUND: Diabetic ketoacidosis (DKA) is one of the most common and harmful complications of type 1 diabetes in children. The neurologic morbidities, including seizure activity, motor/sensory deficit, and coma, can be seen secondary to cerebral edema, hemorrhage, or ischemia. Alpha-frequency is a normal 8-13 Hz physiologic electroencephalogram rhythm that is seen most prominently in the occipital region of awake people and is augmented by eye closure. In the comatose patient, alpha-rhythm is not usually seen. Alpha-frequency coma (AC) is a rare finding in comatose patients and is generally associated with a poor prognosis. CASE REPORT: We report an adolescent with severe DKA, intraparenchymal cerebral hemorrhage, and AC, who had a rapid resolution of the neurologic symptoms. CONCLUSIONS: Similar to other reported cases, our case suggests that the prognosis for patients with AC may not be always poor when it is associated with DKA.

A set of imprinted genes required for normal body growth also promotes growth of rhabdomyosarcoma cells.

INTRODUCTION: In many normal tissues, proliferation rates decline postnatally, causing somatic growth to slow. Previous evidence suggests that this decline is due, in part, to decline in the expression of growth-promoting imprinted genes including Mest, Plagl1, Peg3, Dlk1, and Igf2. Embryonal cancers are composed of cells that maintain embryonic characteristics and proliferate rapidly in childhood. We hypothesized that the abnormal persistent rapid proliferation in embryonal cancers occurs in part because of abnormal persistent high expression of growth-promoting imprinted genes. RESULTS: Analysis of microarray data showed elevated expression of MEST, PLAGL1, PEG3, DLK1, and IGF2 in various embryonal cancers, especially rhabdomyosarcoma, as compared to nonembryonal cancers and normal tissues. Similarly, mRNA expression, assessed by real-time PCR, of MEST, PEG3, and IGF2 in rhabdomyosarcoma cell lines was increased as compared to nonembryonal cancer cell lines. Furthermore, siRNA-mediated knockdown of MEST, PLAGL1, PEG3, and IGF2 expression inhibited proliferation in Rh30 rhabdomyosarcoma cells. DISCUSSION: These findings suggest that the normal postnatal downregulation of growth-promoting imprinted genes fails to occur in some embryonal cancers, particularly rhabdomyosarcoma, and contributes to the persistent rapid proliferation of rhabdomyosarcoma cells and, more generally, that failure of the mechanisms responsible for normal somatic growth deceleration can promote tumorigenesis.

The galactocele of male infants: an intriguing entity. Study and reflection about a case, with review of the literature.

In this report, the authors investigate and discuss a galactocele that developed in the breast of a 5-month-old male. Based on the histological and immunohistochemical findings, they suggest that the rare and intriguing process that is exclusively observed in males in the absence of any detectable hormonal stimulation at time of investigation could represent a developmental anomaly possibly promoted by an obstructive phenomenon involving a defect of hollowing of some primary epidermal buds, the precursors of the mammary ducts.

Stimulatory effects of insulin-like growth factor-I on growth plate chondrogenesis are mediated by nuclear factor-kappaB p65.

Insulin-like growth factor-I (IGF-I) is an important regulator of endochondral ossification. However, little is known about the signaling pathways activated by IGF-I in growth plate chondrocytes. We have previously shown that NF-kappaB-p65 facilitates growth plate chondrogenesis. In this study, we first cultured rat metatarsal bones with IGF-I and/or pyrrolidine dithiocarbamate (PDTC), a known NF-kappaB inhibitor. The IGF-I-mediated stimulation of metatarsal growth and growth plate chondrogenesis was neutralized by PDTC. In rat growth plate chondrocytes, IGF-I induced NF-kappaB-p65 nuclear translocation. The inhibition of NF-kappaB-p65 expression and activity (by p65 short interfering RNA and PDTC, respectively) in chondrocytes reversed the IGF-I-mediated induction of cell proliferation and differentiation and the IGF-I-mediated prevention of cell apoptosis. Moreover, the inhibition of the phosphatidylinositol 3-kinase and Akt abolished the effects of IGF-I on NF-kappaB activation. In conclusion, our findings indicate that IGF-I stimulates growth plate chondrogenesis by activating NF-kappaB-p65 in chondrocytes.

Hypocalcemia in a patient with osteosarcoma and 22q11.2 deletion syndrome.

Hypocalcemia is a rare complication of osteosarcoma, having been described in only 4 reports. We present the case of a 16-year-old male with metastatic osteosarcoma of the right humerus who was found to have severe asymptomatic hypocalcemia. Cytogenetic analysis of peripheral blood revealed a microdeletion in band 22q11.2. Following amputation of the tumor-bearing extremity, the patient's calcium levels increased, but did not normalize. These findings suggested that the etiology of his hypocalcemia was osteoblastic utilization of calcium by the tumor, exacerbated by 22q11.2 deletion syndrome.

Short stature in partially corrected X-linked severe combined immunodeficiency--suboptimal response to growth hormone.

BACKGROUND: X-linked severe combined immunodeficiency (XSCID) results from defects in the common cytokine receptor gamma chain (gamma c) required for signaling by receptors for interleukin (IL)-2, -4, -7, -9, -15, and -21. Following haploidentical bone marrow transplant without myelo-conditioning for XSCID, most patients achieve partial reconstitution often limited to T lymphocytes. Many partially corrected patients manifest extreme short stature (<5th percentile). Previous reports have implicated gamma c in growth hormone (GH) receptor signaling, thus severe growth failure in XSCID may be related to the underlying gamma c defect. AIM: To evaluate the GH/insulin-like growth factor-I (IGF-I) axis in three children with XSCID and partial immune reconstitution with profound growth failure. METHODS: The IGF-I generation test was performed by administering recombinant GH subcutaneously for 5 days, and measuring serum levels for IGF-I before GH injection, and on days 5 and 8. RESULTS: Study of the somatotropic axis revealed profoundly diminished IGF-I production following rGH challenge in all three patients. CONCLUSION: The data indicate that the GH/IGF-I axis in these partially corrected XSCID patients with severe short stature is profoundly impaired, and supports previous studies suggesting that the underlying gamma c defect may contribute to the severe growth failure in XSCID. This supports a role for defective gamma c in the extreme short stature of XSCID, and raises the possibility of recombinant IGF-I treatment to bypass this defect.

Nuclear factor-kappaB p65 facilitates longitudinal bone growth by inducing growth plate chondrocyte proliferation and differentiation and by preventing apoptosis.

NF-kappaB is a group of transcription factors involved in cell proliferation, differentiation, and apoptosis. Mice deficient in the NF-kappaB subunits p50 and p52 have retarded growth, suggesting that NF-kappaB is involved in bone growth. Yet, it is not clear whether the reduced bone growth of these mice depends on the lack of NF-kappaB activity in growth plate chondrocytes. Using cultured rat metatarsal bones and isolated growth plate chondrocytes, we studied the effects of two NF-kappaB inhibitors (pyrrolidine dithiocarbamate (PDTC) or BAY11-7082 (BAY)), p65 short interference RNA (siRNA), and of the overexpression of p65 on chondrocyte proliferation, differentiation, and apoptosis. To further define the underlying mechanisms, we studied the functional interaction between NF-kappaB p65 and BMP-2 in chondrocytes. PDTC and BAY suppressed metatarsal linear growth. Such growth inhibition resulted from decreased chondrocyte proliferation and differentiation and from increased chondrocyte apoptosis. In cultured chondrocytes, the inhibition of NF-kappaB p65 activation (by PDTC and BAY) and expression (by p65 siRNA) led to the same findings observed in cultured metatarsal bones. In contrast, overexpression of p65 in cultured chondrocytes induced chondrocyte proliferation and differentiation and prevented apoptosis. Although PDTC, BAY, and p65 siRNA reduced the expression of BMP-2 in cultured growth plate chondrocytes, the overexpression of p65 increased it. The addition of Noggin, a BMP-2 antagonist, neutralized the stimulatory effects of p65 on chondrocyte proliferation and differentiation, as well as its anti-apoptotic effect. In conclusion, our findings indicate that NF-kappaB p65 expressed in growth plate chondrocytes facilitates growth plate chondrogenesis and longitudinal bone growth by inducing BMP-2 expression and activity.