Skinly: A novel handheld IoT device for validating biophysical skin characteristics.

BACKGROUND: Recent advancements in artificial intelligence have revolutionized dermatological diagnostics. These technologies, particularly machine learning (ML), including deep learning (DL), have shown accuracy equivalent or even superior to human experts in diagnosing skin conditions like melanoma. With the integration of ML, including DL, the development of at home skin analysis devices has become feasible. To this end, we introduced the Skinly system, a handheld device capable of evaluating various personal skin characteristics noninvasively. MATERIALS AND METHODS: Equipped with a moisture sensor and a multi-light-source camera, Skinly can assess age-related skin parameters and specific skin properties. Utilizing state-of-the-art DL, Skinly processed vast amounts of images efficiently. The Skinly system's efficacy was validated both in the lab and at home, comparing its results to established "gold standard" methods. RESULTS: Our findings revealed that the Skinly device can accurately measure age-associated parameters, that is, facial age, skin evenness, and wrinkles. Furthermore, Skinly produced data consistent with established devices for parameters like glossiness, skin tone, redness, and porphyrin levels. A separate study was conducted to evaluate the effects of two moisturizing formulations on skin hydration in laboratory studies with standard instrumentation and at home with Skinly. CONCLUSION: Thanks to its capability for multi-parameter measurements, the Skinly device, combined with its smartphone application, holds the potential to replace more expensive, time-consuming diagnostic tools. Collectively, the Skinly device opens new avenues in dermatological research, offering a reliable, versatile tool for comprehensive skin analysis.

Fragmentation of the mitochondrial network in skin in vivo.

Mitochondria form dynamic networks which adapt to the environmental requirements of the cell. We investigated the aging process of these networks in human skin cells in vivo by multiphoton microscopy. A study on the age-dependency of the mitochondrial network in young and old volunteers revealed that keratinocytes in old skin establish a significantly more fragmented network with smaller and more compact mitochondrial clusters than keratinocytes in young skin. Furthermore, we investigated the mitochondrial network during differentiation processes of keratinocytes within the epidermis of volunteers. We observe a fragmentation similar to the age-dependent study in almost all parameters. These parallels raise questions about the dynamics of biophysical network structures during aging processes.

Impaired CK1 delta activity attenuates SV40-induced cellular transformation in vitro and mouse mammary carcinogenesis in vivo.

Simian virus 40 (SV40) is a powerful tool to study cellular transformation in vitro, as well as tumor development and progression in vivo. Various cellular kinases, among them members of the CK1 family, play an important role in modulating the transforming activity of SV40, including the transforming activity of T-Ag, the major transforming protein of SV40, itself. Here we characterized the effects of mutant CK1δ variants with impaired kinase activity on SV40-induced cell transformation in vitro, and on SV40-induced mammary carcinogenesis in vivo in a transgenic/bi-transgenic mouse model. CK1δ mutants exhibited a reduced kinase activity compared to wtCK1δ in in vitro kinase assays. Molecular modeling studies suggested that mutation N172D, located within the substrate binding region, is mainly responsible for impaired mutCK1δ activity. When stably over-expressed in maximal transformed SV-52 cells, CK1δ mutants induced reversion to a minimal transformed phenotype by dominant-negative interference with endogenous wtCK1δ. To characterize the effects of CK1δ on SV40-induced mammary carcinogenesis, we generated transgenic mice expressing mutant CK1δ under the control of the whey acidic protein (WAP) gene promoter, and crossed them with SV40 transgenic WAP-T-antigen (WAP-T) mice. Both WAP-T mice as well as WAP-mutCK1δ/WAP-T bi-transgenic mice developed breast cancer. However, tumor incidence was lower and life span was significantly longer in WAP-mutCK1δ/WAP-T bi-transgenic animals. The reduced CK1δ activity did not affect early lesion formation during tumorigenesis, suggesting that impaired CK1δ activity reduces the probability for outgrowth of in situ carcinomas to invasive carcinomas. The different tumorigenic potential of SV40 in WAP-T and WAP-mutCK1δ/WAP-T tumors was also reflected by a significantly different expression of various genes known to be involved in tumor progression, specifically of those involved in wnt-signaling and DNA repair. Our data show that inactivating mutations in CK1δ impair SV40-induced cellular transformation in vitro and mouse mammary carcinogenesis in vivo.

While p73 is essential, p63 is completely dispensable for the development of the central nervous system.

The ancient p53 paralogs p63 and p73 regulate specific tissue formation, cell survival and cell death via their TA and ΔN isoforms. Targeted disruption of the p73 locus leads to severe defects in the development of the central nervous system (CNS), and p73 has recently been shown to be an essential regulator of neural stem cell maintenance and differentiation in both embryonal and adult neurogenesis. In contrast, global p63-/- mice lack skin and limbs. Moreover, p63 is detectable in embryonic cortex. It has previously been proposed to also play critical pro-death and pro-survival roles in neural precursors of the developing sympathetic and central nervous system, respectively, based on experimental overexpression and siRNA-mediated knockdown of p63. Here we perform an extensive analysis of the developing central nervous system in global p63-/- mice and their wildtype littermates. Brain and spinal cord of embryos and newborn mice were assessed in vivo for neuroanatomy, histology, apoptosis, proliferation, stemness and differentiation, and in vitro for self-renewal and maturation in neurosphere assays. None of these analyses revealed a detectable phenotype in p63-/- mice. Hence, despite the profound impact of p63 on the development of stratified epithelia and limbs, p63 is completely dispensable for proper development of the central nervous system. Thus, despite their strong homology, the non-overlapping tissue specificity of p63 and p73 functions appears more pronounced than previously anticipated.

p53-Responsive micrornas 192 and 215 are capable of inducing cell cycle arrest.

microRNAs provide a novel layer of regulation for gene expression by interfering with the stability and/or translation of specific target mRNAs. Overall levels of microRNAs are frequently down-regulated in cancer cells, and reducing general microRNA processing increases cancerogenesis in transgenic models, suggesting that at least some microRNAs might act as effectors in tumor suppression. Accordingly, the tumor suppressor p53 up-regulates miR-34a, a microRNA that contributes to apoptosis and acute senescence. Here, we used array hybridization to find that p53 induces two additional, mutually related clusters of microRNAs, leading to the up-regulation of miR-192, miR-194, and miR-215. The same microRNAs were detected at high levels in normal colon tissue but were severely reduced in many colon cancer samples. On the other hand, miR-192 and its cousin miR-215 can each contribute to enhanced CDKN1A/p21 levels, colony suppression, cell cycle arrest, and cell detachment from a solid support. These effects were partially dependent on the presence of wild-type p53. Antagonizing endogenous miR-192 attenuated 5-fluorouracil-induced accumulation of p21. Hence, miR-192 and miR-215 can act as effectors as well as regulators of p53; they seem to suppress cancerogenesis through p21 accumulation and cell cycle arrest.

p53's mitochondrial translocation and MOMP action is independent of Puma and Bax and severely disrupts mitochondrial membrane integrity.

p53's apoptotic program consists of transcription-dependent and transcription-independent pathways. In the latter, physical interactions between mitochondrial p53 and anti- and pro-apoptotic members of the Bcl2 family of mitochondrial permeability regulators are central. Using isogenic cell systems with defined deficiencies, we characterize in detail how mitochondrial p53 contributes to mitochondrial permeabilization, to what extent its action depends on other key Bcl2 family members and define its release activity. We show that mitochondrial p53 is highly efficient in inducing the release of soluble and insoluble apoptogenic factors by severely disrupting outer and inner mitochondrial membrane integrity. This action is associated with wild-type p53-induced oligomerization of Bax, Bak and VDAC and the formation of a stress-induced endogenous complex between p53 and cyclophilin D, normally located at the inner membrane. Tumor-derived p53 mutants are deficient in activating the Bax/Bak lipid pore. These actions are independent of Puma and Bax. Importantly, the latter distinguishes the mitochondrial from the cytosolic p53 death pathway.

Monoubiquitylation promotes mitochondrial p53 translocation.

A major function of the p53 tumor suppressor is the induction of a pleiotropic apoptotic program in response to stress through transcription-dependent and -independent mechanisms. In particular, this includes a direct apoptotic role of p53 at the mitochondria. Stress-induced p53 translocation to the mitochondria with subsequent outer membrane permeabilization is a common early component in p53-mediated apoptosis in normal and transformed cells. However, the mechanism of p53 delivery to the mitochondria remains unknown. Here, we show that the cytoplasm contains a separate and distinct p53 pool that is the major source for p53 translocation to the mitochondria upon its stress-induced stabilization. Using various manipulations that enhance or diminish p53 ubiquitylation, our data provide evidence that Mdm2-mediated monoubiquitylation of p53 greatly promotes its mitochondrial translocation and thus its direct mitochondrial apoptosis. On the other hand, p53 does not require Mdm2 as a shuttler. Upon arrival at the mitochondria, our data suggest that p53 undergoes rapid deubiquitylation by mitochondrial HAUSP via a stress-induced mitochondrial p53-HAUSP complex. This generates the apoptotically active non-ubiquitylated p53. Taken together, we propose a novel model for mitochondrial p53 targeting, whereby a distinct cytoplasmic pool of stabilized monoubiquitylated p53, generated in resting cells by basal levels of Mdm2-type ligases, is subject to a binary switch from a fate of inactivation via subsequent polyubiquitylation and degradation in unstressed cells, to a fate of activation via mitochondrial trafficking.

Casein kinase 1 delta (CK1delta) interacts with the SNARE associated protein snapin.

In this study we identified snapin as an interaction partner of the CK1 isoform delta (CK1delta) in the yeast two-hybrid system and localized the interacting domains of both proteins. The interaction of CK1delta with snapin was confirmed by co-immunoprecipitation. Snapin was phosphorylated by CK1delta in vitro. Both proteins localized in close proximity in the perinuclear region, wherein snapin was found to associate with membranes of the Golgi apparatus. The identification of snapin as a new substrate of CK1delta points towards a possible function for CK1delta in modulating snapin specific functions.

Viral and cellular oncogenes induce rapid mitochondrial translocation of p53 in primary epithelial and endothelial cells early in apoptosis.

In p53-dependent apoptosis in response to genotoxic and hypoxic stress, a fraction of induced wild-type p53 rapidly translocates to mitochondria, triggering a rapid first wave of mitochondrial membrane permeabilization and apoptosis that is later fortified by the transcriptional program of p53. However, whether this direct mitochondrial program also occurs upon oncogenic stress is unknown. In normal cells, oncogenic signals can induce a p53-dependent fail-safe mechanism to counter uncontrolled proliferation by engaging p53-dependent apoptosis. To address whether mitochondrial p53 contributes to oncogene-induced fail-safe apoptosis, p53 translocation was determined in primary human epithelial and endothelial cells overexpressing c-Myc, E1A or E2F1. Serum starvation of these cells, but not of control cells, triggered rapid p53 accumulation at mitochondria, accompanied by cytochrome c and SMAC release and followed by apoptosis. Our data establishes the contribution of the transcription-independent mitochondrial p53 pathway to apoptosis of primary cells in response to deregulated oncogenes.

Transcription-independent pro-apoptotic functions of p53.

Induction of apoptosis is one of the central activities by which p53 exerts its tumor-suppressing function. Aside from its primary function as a transcription factor, it can promote apoptosis independent of transcription. Recent studies have started to define the mechanisms of non-transcriptional pro-apoptotic p53 activities operating within the intrinsic mitochondria-mediated pathway of apoptosis. So far, two different mechanisms have been described, each of which was assigned to a specific localization of the p53 protein, either in the cytosol or directly at the mitochondria. Although mechanistically different, both transcription-independent modes of apoptosis induction converge, as they both initiate permeabilization of the outer mitochondrial membrane via activation of the pro-apoptotic Bcl-2 family members Bax or Bak.

The role of the casein kinase 1 (CK1) family in different signaling pathways linked to cancer development.

The members of the casein kinase 1 (CK1) family are highly conserved and are expressed in many eukaryotes ranging from yeast to humans. Mammalian CK1 isoforms (alpha, beta, gamma, delta, epsilon) and their splice variants are involved in diverse cellular processes including membrane trafficking, circadian rhythm, cell cycle progression, chromosome segregation, apoptosis and cellular differentiation. Mutations and deregulation of CK1 expression and activity has been linked to various diseases including neurodegenerative disorders such as Alzheimer's and Parkinson's disease, sleeping disorders and proliferative diseases such as cancer. In this review, we summarize the functions of CK1 and outline the participation of CK1 in signal transduction pathways linked to cancer development.

Illustration of pneumococcal polysaccharide capsule during adherence and invasion of epithelial cells.

The capsular polysaccharide of Streptococcus pneumoniae represents an important virulence factor and protects against phagocytosis. In this study the amount of capsular polysaccharide present on the bacterial surface during the infection process was illustrated by electron microscopic studies. After infection of A549 cells (type II pneumocytes) and HEp-2 epithelial cells a modified fixation method was used that allowed visualization of the state of capsule expression. This modified fixation procedure did not require the use of capsule-specific antibodies. Visualization of pneumococci in intimate contact and invading cells demonstrated that pneumococci were devoid of capsular polysaccharide. Pneumococci not in contact with the cells did not show alterations in capsular polysaccharide. After infection of the cells, invasive pneumococci of different strains and serotypes were recovered. Single colonies of these recovered pneumococci exhibited an up-to-10(5)-fold-enhanced capacity to adhere and an up-to-10(4)-fold-enhanced capacity to invade epithelial cells. Electron microscopic studies using a lysine-ruthenium red (LRR) fixation procedure or cryo-field emission scanning electron microscopy revealed a reduction in capsular material, as determined in detail for a serotype 3 pneumococcal strain. The amount of polysaccharide in the serotype 3 capsule was also determined after intranasal infection of mice. This study illustrates for the first time the phenotypic variation of the polysaccharide capsule in the initial phase of pneumococcal infections. The modified LRR fixation allowed monitoring of the state of capsule expression of pathogens during the infectious process.

Interaction of casein kinase 1 delta (CK1 delta) with the light chain LC2 of microtubule associated protein 1A (MAP1A).

CK1delta, a member of the casein kinase 1 family of serine/threonine specific kinases, has been shown to be involved in the regulation of microtubule dynamics. We have now identified a 176 aa fragment of the light chain LC2 of MAP1A (termed LC2-P16) specifically interacting with CK1delta. Two CK1delta interacting domains of LC2 were identified, located between aa 2629 and 2753 close to aa 2683 and between aa 2712 and 2805 of LC2. The two regions necessary for the interaction of LC2 with CK1delta have been mapped between aa 76-103 and aa 351-375 of CK1delta. Furthermore, LC2 has been identified as a new substrate of CK1delta. We therefore propose a model in which CK1delta could modulate microtubule dynamics by changing the phosphorylation status of the light chain LC2 of MAP1A.

The casein kinase 1 family: participation in multiple cellular processes in eukaryotes.

Phosphorylation of serine, threonine and tyrosine residues by cellular protein kinases plays an important role in the regulation of various cellular processes. The serine/threonine specific casein kinase 1 and 2 protein kinase families--(CK1 and CK2)--were among the first protein kinases that had been described. In recent years our knowledge of the regulation and function of mammalian CK1 kinase family members has rapidly increased. Extracellular stimuli, the subcellular localization of CK1 isoforms, their interaction with various cellular structures and proteins, as well as autophosphorylation and proteolytic cleavage of their C-terminal regulatory domains influence CK1 kinase activity. Mammalian CK1 isoforms phosphorylate many different substrates among them key regulatory proteins involved in the control of cell differentiation, proliferation, chromosome segregation and circadian rhythms. Deregulation and/or the incidence of mutations in the coding sequence of CK1 isoforms have been linked to neurodegenerative diseases and cancer. This review will summarize our current knowledge about the function and regulation of mammalian CK1 isoforms.