Increased expression of humanin peptide in diffuse-type pigmented villonodular synovitis: implication of its mitochondrial abnormality

Evidence of natural selection in the mitochondrial-derived peptides humanin and SHLP6

Mitochondrial-derived peptides are encoded by mitochondrial DNA but have biological activity outside mitochondria. Eight of these are encoded by sequences within the mitochondrial 12S and 16S ribosomal genes: humanin, MOTS-c, and the six SHLP peptides, SHLP1-SHLP6. These peptides have various effects in cell culture and animal models, affecting neuroprotection, insulin sensitivity, and apoptosis, and some are secreted, potentially having extracellular signaling roles. However, except for humanin, their importance in normal cell function is unknown. To gauge their importance, their coding sequences in vertebrates have been analyzed for synonymous codon bias. Because they lie in RNA genes, such bias should only occur if their amino acids have been conserved to maintain biological function. Humanin and SHLP6 show strong synonymous codon bias and sequence conservation. In contrast, SHLP1, SHLP2, SHLP3, and SHLP5 show no significant bias and are poorly conserved. MOTS-c and SHLP4 also lack significant bias, but contain highly conserved N-terminal regions, and their biological importance cannot be ruled out. An additional potential mitochondrial-derived peptide sequence was discovered preceding SHLP2, named SHLP2b, which also contains a highly conserved N-terminal region with synonymous codon bias.

cIAP2 expression and clinical significance in pigmented villonodular synovitis

Pigmented villonodular synovitis (PVNS) is a rare hyperplasia disease of the synovium with a predilection for the knee in either a localized (LPVNS) or a diffuse form (DPVNS). But the exact cause is not clear. The aim of this study was to explore the relationship between the expression of cellular inhibitor of apoptosis 2 (cIAP2) and proliferation, apoptosis, invasive growth and postoperative recurrence in PVNS. Clinical significance of cIAP2 expression in synovium from 63 patients' knee joints with PVNS (40 DPVNS; 23 LPVNS) were investigated with 20 normal subjects acting as controls. The cIAP2 gene was screened by Human Cancer Pathway Finder PCR Array and real-time polymerase chain reaction (RT-PCR). We also used immunohistochemistry to detect cIAP2 and proliferating cell nuclear antigen (PCNA) protein expression and analyzed their relationship with PVNS type, invasive growth, and postoperative recurrence. The expression of cIAP2, PCNA, caspase-8, caspase-9 and caspase-3 protein was tested in Western blot. Screening results of Human Cancer Pathway Finder PCR array and RT-PCR showed significantly more cIAP2 mRNA in DPVNS synovium than in normal or LPVNS synovium (P < 0.05). Immunohistochemistry and western blot showed that the cIAP2 protein expression level in DPVNS was significantly higher than in LPVNS tissue (P < 0.01). As cIAP2 expression increased, the expression of PCNA increased (P < 0.05) and expression of cleaved caspase-3, -8, -9 decreased (P < 0.01). cIAP2 and PCNA overexpression were found to be related to ligament and bone erosion in PVNS and to disease recurrence (P < 0.05). This study suggested that cIAP2 overexpression plays an important role in the anti-apoptotic, proliferative and invasive growth of PVNS, which may account for the recurrence and poor prognosis of DPVNS.

Humanin gene expression in fibroblast of Down syndrome subjects

Down syndrome (DS) is characterized by trisomy of chromosome 21 and peculiar phenotype. Humanin (HN) is a mitochondrial short 24-residue polypeptide whit anti-apoptotic and neuroprotective effects. In this study we evaluated HN protein expression and HN mRNA levels in cultured fibroblasts from DS patients and normal controls. Our results obtained by immunocytochemistry, western-blot and qRT-PCR analysis show a significant HN up-regulation in DS patients. These results confirm previous studies and suggest a role for HN may in the DS phenotype.

Pigmented villonodular synovitis in a child: A missed diagnosis

Paediatric joint pain and swelling is a frequent presentation. The clinical profile and relevant laboratory investigations often lead to the correct diagnosis; however some patients present a diagnostic conundrum. Pigmented villonodular synovitis (PVNS) is a rare entity that may afflict children and be easily missed.

Long-term outcome of pigmented villonodular synovitis of the hip after joint preserving therapy

INTRODUCTION

Pigmented villonodular synovitis (PVNS) is a rare, destructive synovial disease that affects the hip joint the second most common after the knee. However, in contrast, joint preserving surgery in the hip joint is considered to be significantly more difficult or even impossible due to earlier occurrence of osteochondral dissemination and surgical difficulties. Today, earlier diagnosis due to the generous use of MRI and modern surgical strategies raise hope for improved outcomes.

METHODS

Since 2005, six patients with PVNS of the hip and a minimal follow-up of 2 years underwent joint preserving surgery in our institution (mean age 20.5 years, range 14-27). After PVNS was suspected in the MRI and confirmed by arthroscopic biopsy (four diffuse, two focal forms), synovectomy was carried out in 5 patients via surgical hip dislocation and in one focal case via arthroscopy. In diffuse forms, adjuvant radiosynoviorthesis (RSO) was conducted 6-8 week postoperatively. MRI and clinical examinations were performed during follow-up.

RESULTS

After a mean follow-up of 8 years (range 35-141 months), five of six patients did not show recurrence or secondary osteoarthritis. Clinical outcome evaluation resulted in a mean modified Harris Hip Score of 91 points (range 67-100 points). A 21-year-old patient with a diffuse form and advanced osteochondral involvement at the time of diagnosis was eventually treated by total hip arthroplasty.

CONCLUSION

In cases without osteochondral involvement, recurrence-free long-term results without progression of joint degeneration can be achieved by joint preserving therapy.

Humanin: Functional Interfaces with IGF-I

Humanin is the first newly discovered peptide encoded in the mitochondrial genome in over three decades. It is the first member of a novel class of mitochondrial derived peptides. This small, 24 amino acid peptide was initially discovered to have neuroprotective effects and subsequent experiments have shown that it is beneficial in a diverse number of disease models including stroke, cardiovascular disease, and cancer. Over a decade ago, our lab found that humanin bound IGFBP-3 and more recent studies have found it to decrease circulating IGF-I levels. In turn, IGF-I also seems to regulate humanin levels and in this review, we cover the known interaction between humanin and IGF-I. Although the exact mechanism for how humanin and IGF-I regulate each other still needs to be elucidated, it is clear that humanin is a new player in IGF-I signaling.

Humanin binds MPP8: mapping interaction sites of the peptide and protein

Humanin (HN), a 24-amino acid peptide encoded by the mitochondrial 16S rRNA gene, was discovered by screening a cDNA library from the occipital cortex of a patient with Alzheimer's disease (AD) for a protection factor against AD-relevant insults. Earlier, using the yeast two-hybrid system, we have identified the M-phase phosphoprotein 8 (MPP8) as a binding partner for HN. In the present work, we further confirmed interaction of HN with MPP8 in co-immunoprecipitation experiments and localized an MPP8-binding site in the region between 5 and 12 aa. of HN. We have also shown that an MPP8 fragment (residues 431-560) is sufficient to bind HN. Further studies on functional consequences of the interaction between the potential oncopetide and the oncoprotein may elucidate some aspects of the molecular mechanisms of carcinogenesis.

Extra-articular diffuse-type giant cell tumour of the temporomandibular joint

Diffuse-type giant cell tumour (DTGCT) is a benign but destructive proliferative disorder of the synovium of joint capsules, tendons and bursae. Lesions originating from the articular synovium may grow intra-articularly or expand widely extra-articularly. Rare cases may develop only in peri-articular tissues. Temporomandibular joint (TMJ) involvement is exceptional and only two cases of purely extra-articular TMJ-DTGCT have been reported. The authors report an additional case of extra-articular TMJ-DTGCT. The clinical features, histopathological characteristics, imaging modalities and diagnostic methods for DTGCT are discussed together with a literature review based on the clinical aspects of TMJ involvement.

Pigmented villonodular synovitis of joints

OBJECTIVES

The objective of this study is to present two series of cases of pigmented villonodular disease of joints (PVNS) treated at different periods. The 215 cases from our hospital are current (1972-2009) and those 62 from the Jaffe collection from 1920 to 1968.

METHODS

By use of our computerized tumor data system we were able to define age, gender, site, treatment, complications, and outcome. Examination of the material from the Jaffe collection included all of the above primary data but none on treatment and outcome.

RESULTS

The data for the two systems studied were remarkably similar. The average ages were in mid years and the disorder was more frequent in females. The largest numbers of cases for both series were in the knee and foot and less commonly in hip, shoulder, and hand. The treatments were mostly surgical excision with the exception of the hip which required total hip replacement. The results show only a small number of recurrences, no metastatic disease and no deaths.

CONCLUSION

Pigmented villonodular disease of joints is a rare entity, mostly occurring in the knee and foot. The principal treatment is surgical excision which is most often successful in these sites but leads to problems at other locations, especially the hip.

Evidence for potential functionality of nuclearly-encoded humanin isoforms

Humanin (HN) is a recently identified neuroprotective and antiapoptotic peptide derived from a portion of the mitochondrial MT-RNR2 gene. We provide bioinformatic and expression data suggesting the existence of 13 MT-RNR2-like nuclear loci predicted to maintain the open reading frames of 15 distinct full-length HN-like peptides. At least ten of these nuclear genes are expressed in human tissues, and respond to staurosporine (STS) and beta-carotene. Sequence comparisons of the nuclear HN isoforms and their homologues in other species reveal two consensus motifs, encompassing residues 5-11 (GFS/NCLLL), and 14-19 (SEIDLP/S). Proline vs serine in position 19 may determine whether the peptide is secreted or not, while threonine in position 13 may be important for cell surface receptor binding. Cytoprotection against the STS-induced apoptosis conferred by the polymorphic HN5 variant, in which threonine in position 13 is replaced with isoleucine, is reduced compared to the wild type HN5 peptide.