Rapid, sequential changes in surface morphology of PC12 pheochromocytoma cells in response to nerve growth factor

The effect of nerve growth factor (NGF), a substance that promotes the differentiation and maintenance of certain neurons, was studied via scanning electron microscopy utilizing the PC12 clonal NGF-responsive pheochromocytoma cell line. After 2-4 d of exposure to NGF, these cells acquire many of the properties of normal sympathic neurons. However, by phase microscopy, no changes are discernible within the first 12-18 h. Since the primary NGF receptor appears to be a membrane receptor, it seemed likely that some of the initial responses to the factor may be surface related. PC12 cells maintained without NGF are round to ovoid and have numerous microvilli and small blebs. After the addition of NGF, there is a rapidly initiated sequential change in the cell surface. Ruffles appear over the dorsal surface of the cells with 1 min, become prominent by 3 min, and almost disappear by 7 min. Microvilli, conversely, disappear as the dorsal ruffles become prominent. Ruffles are seen at the the periphery of cell at 3 min, are prominent on most of the cells by 7 min and are gone by 15 min. The surface remains smooth from 15 min until 45 min when large blebs appear. The large blebs are present on most cells at 2 h and are gone by 4 h. The surface remains relatively smooth until 6-7 h of NGF treatment, when microvilli reappear as small knobs. These microvilli increase in both number and length to cover the cell surface by 10 h. These changes were not observed with other basic proteins, with α-bungarotoxin (which binds specifically to PC12 membranes), and were not affected by an RNA synthesis inhibitor that blocks initiation of neurite outgrowth. Changes in the cell surface architecture appear to be among the earlist NGF responses yet detected and may represent or reflect primary events in the mechanism of the factor’s action.     

Non-synonymous polymorphisms in the P2RX 4 are related to bone mineral density and osteoporosis risk in a cohort of Dutch fracture patients

In the present study we investigated whether single nucleotide polymorphisms (SNPs) in the P2RX₄, which alter the P2X₄R function, are associated with the development of osteoporosis and whether an interaction between the P2X₄R and P2X₇R confer a synergistic effect of these two receptors on osteoporosis risk. Patients with fracture (690 females and 231 males, aged ≥50 years) were genotyped for three non-synonymous P2X₄R SNPs. Bone mineral density (BMD) was measured at the total hip, lumbar spine, and femoral neck. Subject carrying the variant allele of the Tyr315Cys polymorphism showed a 2.68-fold (95 % CI, 1.20–6.02) higher risk of osteoporosis compared with wild-type subject. Furthermore, significant lower lumbar spine BMD values were observed in subjects carrying the Cys315 allele as compared with wild-type (0.85 ± 0.17 and 0.93 ± 0.17 g/cm², respectively; p < 0.001). Assuming a recessive model, carriers of the variant allele of the Ser242Gly polymorphism showed increased BMD values at the lumbar spine compare to wild-type subject (1.11 ± 0.35 and 0.92 ± 0.17 g/cm², respectively; p = 0.0045). This is the first study demonstrating an association of non-synonymous polymorphisms in the P2RX₄ and the risk of osteoporosis, suggesting a role of the P2X₄R in the regulation of bone mass.

Electronic supplementary material

The online version of this article (doi:10.1007/s11302-012-9337-0) contains supplementary material, which is available to authorized users.     

<Emphasis Type="Italic">Mhc</Emphasis> class II diversity and balancing selection in greater prairie-chickens

The major histocompatibility complex (Mhc) of domestic chickens has been characterized as small and relatively simple compared with that of mammals. However, there is growing evidence that the Mhc of many bird lineages may be more complex, even within the Order Galliformes. In this study, we measured genetic variation and balancing selection at Mhc loci in another galliform, the greater prairie-chicken. We cloned and sequenced a 239 bp fragment of Mhc Class II β-chain (BLB) exon 2 in 14 individuals. There was a total of 10 unique sequences and a minimum of four BLB loci. The d _N/d _S ratio at peptide-binding codons was significantly greater than one, suggesting balancing selection is acting on the BLB. We also recovered two YLB sequences, which clustered tightly with YLB sequences from three other species: domestic chicken, black grouse and common quail. The relatively large number of loci revealed in our study suggests that even closely related galliforms differ in the level of Mhc variation and structure.     

SARS-CoV-2 in patients with cancer: possible role of mimicry of human molecules by viral proteins and the resulting anti-cancer immunity

A few reports suggest that molecular mimicry can have a role in determining the more severe and deadly forms of COVID-19, inducing endothelial damage, disseminated intravascular coagulation, and multiorgan failure. Heat shock proteins/molecular chaperones can be involved in these molecular mimicry phenomena. However, tumor cells can display on their surface heat shock proteins/molecular chaperones that are mimicked by SARS-CoV-2 molecules (including the Spike protein), similarly to what happens in other bacterial or viral infections. Since molecular mimicry between SARS-CoV-2 and tumoral proteins can elicit an immune reaction in which antibodies or cytotoxic cells produced against the virus cross-react with the tumor cells, we want to prompt clinical studies to evaluate the impact of SARS-CoV-2 infection on prognosis and follow up of various forms of tumors. These topics, including a brief historical overview, are discussed in this paper.